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Sample records for caffeic acid oligomers

  1. Butylated caffeic acid: An efficient novel antioxidant

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    G. Shi

    2017-09-01

    Full Text Available A novel antioxidant, butylated caffeic acid (BCA was rationally designed by adding a tert-butyl group to caffeic acid, which was synthesized at a high yield (36.2% from 2-methoxy-4-methylphenol by a four-step reaction including Friedel-Crafts alkylation, bromine oxidation, ether bond hydrolysis and Knoevenagel condensation. Its antioxidant capacity was much stronger than common commercial antioxidant tert-butyl hydroquinone (TBHQ and its mother compound, caffeic acid, in both rancimat and deep frying tests. When investigated via the DPPH method, the antioxidant capacity of BCA was almost equal to TBHQ, but lower than caffeic acid. BCA could be a potentially strong antioxidant, especially for food processing at high temperatures such as deep frying and baking.

  2. Butylated caffeic acid: An efficient novel antioxidant

    International Nuclear Information System (INIS)

    Shi, G.; Liao, X.; Olajide, T.M.; Liu, J.; Jiang, X.; Weng, X.

    2017-01-01

    A novel antioxidant, butylated caffeic acid (BCA) was rationally designed by adding a tert-butyl group to caffeic acid, which was synthesized at a high yield (36.2%) from 2-methoxy-4-methylphenol (1) by a four-step reaction including Friedel-Crafts alkylation, bromine oxidation, ether bond hydrolysis and Knoevenagel condensation. Its antioxidant capacity was much stronger than common commercial antioxidant tert-butyl hydroquinone (TBHQ) and its mother compound, caffeic acid, in both rancimat and deep frying tests. When investigated via the DPPH method, the antioxidant capacity of BCA was almost equal to TBHQ, but lower than caffeic acid. BCA could be a potentially strong antioxidant, especially for food processing at high temperatures such as deep frying and baking. [es

  3. Chlorogenic acid and caffeic acid are absorbed in humans

    NARCIS (Netherlands)

    Olthof, Margreet R.; Hollman, Peter C H; Katan, Martijn B.

    2001-01-01

    Chlorogenic acid, an ester of caffeic acid and quinic acid, is a major phenolic compound in coffee; daily intake in coffee drinkers is 0.5-1 g. Chlorogenic acid and caffeic acid are antioxidants in vitro and might therefore contribute to the prevention of cardiovascular disease. However, data on the

  4. Pharmacokinetics of Caffeic Acid from Methanol Seed Extract of ...

    African Journals Online (AJOL)

    Methods: A dose of the extract (500 mg, equivalent to 37.135 mg caffeic acid) was administered orally to 6 male .... emission. Validation studies. Linearity. The rat plasma samples were spiked by caffeic acid solutions ..... Atomic structure of.

  5. Caffeic acid derivative from Clinopodium umbrosum

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    M. Esfahanizadeh

    2017-11-01

    Full Text Available Background and objectives: Plants of genus Clinopodium have been used in different cultures as traditional medicines.Due to theimportance of medicinal properties of the genus Clinopodium, C. umbrosum was selected for phytochemical analysis along with evaluation of its antioxidant property. Methods: The aerial parts of C. umbrosum were extracted with petroleum ether, chloroform, and methanol. Later, the methanol extract was fractionated via solid phase extraction and reversed phase high performance liquid chromatography. Consequently, structure of the isolated compound was analyzed through spectral analysis of 1D and 2D NMR data. Besides, the essential oil of C. umbrosum achieved through hydrodistillation was analyzed via gas chromatography-mass spectrometry (GC-MS. Additionally, the antioxidant property of C. umbrosum methanol extracttogether with its phenolics and flavonoids content were assessed. Results: Structure elucidation of the purified compound revealed presence of a caffeic acid derivative in C. umbrosum methanol extract. GC-MS analysis of the essential oil showed limonene, acetophenone, palmitic acid and phytol as the most frequent components of the essential oil. Moreover, the RC50 value for free radical scavenging activity of  the methanol extract was determined as 38.52 µg/mL and values for the total phenolics and flavonoids contact were calculated as 5.14 g gallic acid equivalent and 4.25 g quercetin equivalent per 100 g of dried plant material, respectively.  Conclusion: Overall, the present study was the first report on the phytochemical analysis of C. umbrosum whichrevealed presence of rosmarinic acid as the main component of the methanol extract with prominent antioxidant activity.

  6. Pharmacokinetics of Caffeic Acid from Methanol Seed Extract of ...

    African Journals Online (AJOL)

    Purpose: To describe caffeic acid-based pharmacokinetics of methanol extract of seed of Syzygium cumini L. in rats. Methods: A dose of the extract (500 mg, equivalent to 37.135 mg caffeic acid) was administered orally to 6 male Wister rats, weighing 200 ± 10 g. Blood samples (0.5 mL), collected from the tail vein at 0, 15, ...

  7. Novel Caffeic Acid Nanocarrier: Production, Characterization, and Release Modeling

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    Milad Fathi

    2013-01-01

    Full Text Available This paper deals with the development of novel nanocarriers using layer by layer carbohydrate coating of caffeic acid loaded solid lipid nanoparticles (SLNs to improve stability and colon delivery of the poorly water-soluble caffeic acid. Three biopolymers (chitosan, alginate, and pectin in different concentrations (0.1, 0.25, and 0.5% were electrostatically coated over the SLN surface. The size and zeta potential of produced nanocarriers were measured using photon correlation spectroscopy. Mathematical models (i.e., zero-order, first-order, Higuchi, Ritger-Peppas, reciprocal powered time, Weibull, and quadratic models were used to describe the release and kinetic modeling in gastrointestinal solution (GIS. Also, antioxidant activity of caffeic acid during the release in GIS was investigated using DPPH and reducing activity methods. The prepared treatments coated by alginate-chitosan as well as pectin-chitosan coated SLN at the concentration of 0.1% showed nanosized bead; the latter efficiently retarded the release of caffeic acid in gastric media up to 2.5 times higher than that of SLN. Zeta potential values of coated samples were found to significantly increase in comparison to SLN indicating the higher stability of produced nanocarriers. Antioxidant activity of caffeic acid after gastric release did not result in the same trend as observed for caffeic acid release from different treatments; however, in line with less caffeic acid release in the intestine solution by the effect of coating, lower antioxidant activity was determined at the end stage of the experiment.

  8. Caffeic Acid Induces Apoptosis in Human Cervical Cancer Cells Through the Mitochondrial Pathway

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    Wei-Chun Chang

    2010-12-01

    Conclusion: Caffeic acid induces apoptosis by inhibiting Bcl-2 activity, leading to release of cytochrome c and subsequent activation of caspase-3, indicating that caffeic acid induces apoptosis via the mitochondrial apoptotic pathway. This also suggests that caffeic acid has a strong anti-tumor effect and may be a promising chemopreventive or chemotherapeutic agent.

  9. Inhibitory mechanism against oxidative stress of caffeic acid

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    Farhan Ahmed Khan

    2016-10-01

    Full Text Available The purpose of this article is to summarize the reported antioxidant activities of a naturally abundant bioactive phenolic acid, caffeic acid (CA, 3,4-dihydroxycinnamic acid, so that new avenues for future research involving CA can be explored. CA is abundantly found in coffee, fruits, vegetables, oils, and tea. CA is among the most potential and abundantly found in nature, hydroxycinnamic acids with the potential of antioxidant behavior. Reactive oxygen species produced as a result of endogenous processes can lead to pathophysiological disturbances in the human body. Foods containing phenolic substances are a potential source for free radical scavenging; these chemicals are known as antioxidants. This review is focused on CA's structure, availability, and potential as an antioxidant along with its mode of action. A brief overview of the literature published about the prooxidant potential of caffeic acid as well as the future perspectives of caffeic acid research is described. CA can be effectively employed as a natural antioxidant in various food products such as oils.

  10. Grape skins (Vitis vinifera L.) catalyze the in vitro enzymatic hydroxylation of p-coumaric acid to caffeic acid

    DEFF Research Database (Denmark)

    Arnous, Anis; Meyer, Anne S.

    2009-01-01

    The ability of grape skins to catalyze in vitro conversion of p-coumaric acid to the more potent antioxidant caffeic acid was studied. Addition of different concentrations of p-coumaric to red grape skins (Cabernet Sauvignon) resulted in formation of caffeic acid. This caffeic acid formation (Y...

  11. Caffeic acid treatment alters the extracellular adenine nucleotide hydrolysis in platelets and lymphocytes of adult rats.

    Science.gov (United States)

    Anwar, Javed; Spanevello, Roselia Maria; Pimentel, Victor Camera; Gutierres, Jessié; Thomé, Gustavo; Cardoso, Andreia; Zanini, Daniela; Martins, Caroline; Palma, Heloisa Einloft; Bagatini, Margarete Dulce; Baldissarelli, Jucimara; Schmatz, Roberta; Leal, Cláudio Alberto Martins; da Costa, Pauline; Morsch, Vera Maria; Schetinger, Maria Rosa Chitolina

    2013-06-01

    This study evaluated the effects of caffeic acid on ectonucleotidase activities such as NTPDase (nucleoside triphosphate diphosphohydrolase), Ecto-NPP (nucleotide pyrophosphatase/phosphodiesterase), 5'-nucleotidase and adenosine deaminase (ADA) in platelets and lymphocytes of rats, as well as in the profile of platelet aggregation. Animals were divided into five groups: I (control); II (oil); III (caffeic acid 10 mg/kg); IV (caffeic acid 50 mg/kg); and V (caffeic acid 100 mg/kg). Animals were treated with caffeic acid diluted in oil for 30 days. In platelets, caffeic acid decreased the ATP hydrolysis and increased ADP hydrolysis in groups III, IV and V when compared to control (P<0.05). The 5'-nucleotidase activity was decreased, while E-NPP and ADA activities were increased in platelets of rats of groups III, IV and V (P<0.05). Caffeic acid reduced significantly the platelet aggregation in the animals of groups III, IV and V in relation to group I (P<0.05). In lymphocytes, the NTPDase and ADA activities were increased in all groups treated with caffeic acid when compared to control (P<0.05). These findings demonstrated that the enzymes were altered in tissues by caffeic acid and this compound decreased the platelet aggregation suggesting that caffeic acid should be considered a potentially therapeutic agent in disorders related to the purinergic system. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Synthesis, Preliminary Bioevaluation and Computational Analysis of Caffeic Acid Analogues

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    Zhiqian Liu

    2014-05-01

    Full Text Available A series of caffeic acid amides were designed, synthesized and evaluated for anti-inflammatory activity. Most of them exhibited promising anti-inflammatory activity against nitric oxide (NO generation in murine macrophage RAW264.7 cells. A 3D pharmacophore model was created based on the biological results for further structural optimization. Moreover, predication of the potential targets was also carried out by the PharmMapper server. These amide analogues represent a promising class of anti-inflammatory scaffold for further exploration and target identification.

  13. Antioxidative effect of lipophilized caffeic acid in fish oil enriched mayonnaise and milk

    DEFF Research Database (Denmark)

    Alemán, Mercedes; Bou, Ricard; Guardiola, Francesc

    2015-01-01

    The antioxidative effect of lipophilized caffeic acid was assessed in two different fish oil enriched food products: mayonnaise and milk. In both emulsion systems, caffeic acid esterified with fatty alcohols of different chain lengths (C1–C20) were better antioxidants than the original phenolic c...

  14. Microencapsulation of caffeic acid phenethyl ester and caffeic acid phenethyl amide by inclusion in hydroxypropyl-β-cyclodextrin.

    Science.gov (United States)

    Garrido, E Manuela P J; Cerqueira, Ana S; Chavarria, Daniel; Silva, Tiago; Borges, Fernanda; Garrido, Jorge M P J

    2018-07-15

    Caffeic acid phenethyl ester (CAPE) is a bioactive polyphenolic compound obtained from propolis extract. Although it has a broad therapeutic potential, the bioavailability of CAPE is limited, due to reduced solubility and poor plasmatic stability. Efforts to reduce these pharmacokinetic drawbacks resulted in the synthesis of caffeic acid phenethyl amide (CAPA). Cyclodextrins have been proved as promising excipients for the formulation of active ingredients. Herein, we report the inclusion complexation behavior and binding ability of CAPE and CAPA with hydroxypropyl-β-cyclodextrin (HP-β-CD). The supramolecular interactions were examined through UV and FTIR spectroscopy, DSC, 1 H NMR and 2D ROESY. The CAPE/HP-β-CD and CAPA/HP-β-CD inclusion complexes stability constants were determined to be, respectively, 2911.6 and 584.6 M -1 in water and 2866.2 and 700.1 M -1 at physiological pH. The aqueous solubility increased notably, proving that HP-β-CD can be potentially useful to improve the biological, chemical and physical properties of CAPE and CAPA. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. In vitro antiviral efficacy of caffeic acid against canine distemper virus.

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    Wu, Zong-Mei; Yu, Zhen-Jiang; Cui, Zhen-Qiang; Peng, Lu-Yuan; Li, Hao-Ran; Zhang, Chun-Lei; Shen, Hai-Qing; Yi, Peng-Fei; Fu, Ben-Dong

    2017-09-01

    Canine distemper (CD) is a highly contagious disease caused by the canine distemper virus (CDV), and mortality can be as high as 100%. However, there is no specific treatment for CD. In this study, the antiviral activity of the caffeic acid against CDV was evaluated in vitro. The results showed that the IC 50 of the caffeic acid against CDV at 1 and 2 h post infection (PI) is 23.3 and 32.3 μg/mL, respectively. Consistently, at 1 and 2 h PI, the caffeic acid exhibited a reduced (23.3-57.0% and 37.2-38.1%) viral inhibitory effect in vero cells. Furthermore, the caffeic acid plus Ribavirin (RBV) has greater antiviral activity against CDV than the caffeic acid or RBV individually. In addition, the caffeic acid reduced the total viral RNA synthesis by 59-86% at 24-72 h. Therefore, our data provided the experimental evidence that the caffeic acid effectively inhibited CDV infection in vero cells, which may potentially be used to treat clinical disease associated with CDV infection. Copyright © 2017. Published by Elsevier Ltd.

  16. Caffeic acid production by simultaneous saccharification and fermentation of kraft pulp using recombinant Escherichia coli.

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    Kawaguchi, Hideo; Katsuyama, Yohei; Danyao, Du; Kahar, Prihardi; Nakamura-Tsuruta, Sachiko; Teramura, Hiroshi; Wakai, Keiko; Yoshihara, Kumiko; Minami, Hiromichi; Ogino, Chiaki; Ohnishi, Yasuo; Kondo, Ahikiko

    2017-07-01

    Caffeic acid (3,4-dihydroxycinnamic acid) serves as a building block for thermoplastics and a precursor for biologically active compounds and was recently produced from glucose by microbial fermentation. To produce caffeic acid from inedible cellulose, separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) reactions were compared using kraft pulp as lignocellulosic feedstock. Here, a tyrosine-overproducing Escherichia coli strain was metabolically engineered to produce caffeic acid from glucose by introducing the genes encoding a 4-hydroxyphenyllactate 3-hydroxylase (hpaBC) from Pseudomonas aeruginosa and tyrosine ammonia lyase (fevV) from Streptomyces sp. WK-5344. Using the resulting recombinant strain, the maximum yield of caffeic acid in SSF (233 mg/L) far exceeded that by SHF (37.9 mg/L). In the SSF with low cellulase loads (≤2.5 filter paper unit/g glucan), caffeic acid production was markedly increased, while almost no glucose accumulation was detected, indicating that the E. coli cells experienced glucose limitation in this culture condition. Caffeic acid yield was also negatively correlated with the glucose concentration in the fermentation medium. In SHF, the formation of by-product acetate and the accumulation of potential fermentation inhibitors increased significantly with kraft pulp hydrolysate than filter paper hydrolysate. The combination of these inhibitors had synergistic effects on caffeic acid fermentation at low concentrations. With lower loads of cellulase in SSF, less potential fermentation inhibitors (furfural, 5-hydroxymethyfurfural, and 4-hydroxylbenzoic acid) accumulated in the medium. These observations suggest that glucose limitation in SSF is crucial for improving caffeic acid yield, owing to reduced by-product formation and fermentation inhibitor accumulation.

  17. Interactive effects of gallic/ferulic/caffeic acids and anthocyanins on pigment thermal stabilities.

    Science.gov (United States)

    Qian, Bing-Jun; Liu, Jian-Hua; Zhao, Shu-Juan; Cai, Jian-Xiong; Jing, Pu

    2017-06-01

    The data presented in this article are related to the research article entitled "The effects of gallic/ferulic/caffeic acids on colour intensification and anthocyanin stability" (Qian et al., 2017) [1]. This paper described preparation and isolation of anthocyanins from purple sweet potatoes (PSP) and the time-course of anthocyanin profiles treated with gallic, ferulic, or caffeic acids at 95 °C. The color appearance of PSPanthocyanins alone, or with gallic, ferulic, or caffeic acids was described after the 15 h of thermal treatment. The high resolution mass spectrographs of PSP anthocyanins were determined using UPLC-ESI-HRMS. The spatial interaction of peonidin 3-O-(2-O-β-D-glucopyranocyl-β-D-glucopyranoide)-5-O-β-D-glucopyranoside and gallic/ferulic/caffeic acids was illustrated by molecular dynamic simulation.

  18. The Sonodegradation of Caffeic Acid under Ultrasound Treatment: Relation to Stability

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    Yujing Sun

    2013-01-01

    Full Text Available The degradation of caffeic acid under ultrasound treatment in a model system was investigated. The type of solvent and temperature were important factors in determining the outcome of the degradation reactions. Liquid height, ultrasonic intensity and duty cycle only affected degradation rate, but did not change the nature of the degradation. The degradation rate of caffeic acid decreased with increasing temperature. Degradation kinetics of caffeic acid under ultrasound fitted a zero-order reaction from −5 to 25 °C. Caffeic acid underwent decomposition and oligomerization reactions under ultrasound. The degradation products were tentatively identified by FT-IR and HPLC-UV-ESIMS to include the corresponding decarboxylation products and their dimers.

  19. Synthesis of labelled compound of ferulic acid and caffeic acid with tritium

    International Nuclear Information System (INIS)

    Yi Mingguang; Wang Caiyun

    1986-01-01

    Effective components of Chinese traditional herbs consist of many compounds, but some of the compounds usually contain unsaturated carbon-carbon double bonds. The unsaturated organic compounds 3 H-Ferulic acid and 3 H-Caffeic acid are prepared with their tritiated intermediates made by electric-dischange exposure method, which ensures the compounds contaning double bonds not hydrogenated. The 3 H-Ferulic acid is composed of 3 H-vanillin and Malonic acid. The 3 H-Caffeic acid is composed of 3 H-protocatechuyl aldehyde and Malonic acid and the specific activity of the products is 0.2 mCi/mg. The radiochemicaly purity is greater than 90%

  20. Preparation and characterization of SPION functionalized via caffeic acid

    International Nuclear Information System (INIS)

    Baykal, A.; Amir, Md.; Günerb, S.; Sözeri, H.

    2015-01-01

    Caffeic acid coated superparamagnetic iron oxide nanoparticles (SPION-CFA) was synthesized by reflux method. The structural, spectroscopic and magnetic properties were studied by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), and Vibrating sample magnetometer (VSM) techniques. Thermal gravimetric analysis (TG) and Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of CA on the surface of SPION. The theoretical analyzes performed on recorded room temperature VSM spectrum confirmed the formation of superparamagnetic nature of SPION-CFA. The particle size dependent Langevin function was applied to determine the average magnetic particle dimension (D mag ) around 11.93 nm. In accordance, the average crystallite and particle sizes were obtained as 11.40 nm and ~12.00 nm from XRD and TEM measurements. The extrapolated specific saturation magnetization (σ s ) is 44.11 emu/g and measured magnetic moment is 1.83 µ B . These parameters assign small order of magnetization for NPs with respect to bulk Fe 3 O 4 . Magnetic anisotropy was offered as uniaxial and calculated effective anisotropy constant (K eff ) is 34.82×10 4 Erg/g. The size-dependent saturation magnetization suggests the existence of a magnetically inactive layer as 1.035 nm for SPION-CFA. - Highlights: • The effects of CFA on the microstructure and magnetic properties of SPION have been investigated. • Product was structurally and magnetically characterized. • Product presented superparamagnetic behavior at room temperature

  1. Aspergillus niger whole-cell catalyzed synthesis of caffeic acid phenethyl ester in ionic liquids.

    Science.gov (United States)

    Rajapriya, Govindaraju; Morya, Vivek Kumar; Mai, Ngoc Lan; Koo, Yoon-Mo

    2018-04-01

    Synthesis of caffeic acid ester essentially requires an efficient esterification process to produce various kinds of medicinally important ester derivatives. In the present study, a comprehensive and comparative analysis of whole-cell catalyzed caffeic acid esters production in ionic liquids (ILs) media was performed. Olive oil induced mycelial mass of halotolerant Aspergillus niger (A.niger) EXF 4321 was freeze dried and used as a catalyst. To ensure maximum solubilization of caffeic acid for highest substrate loading several ILs were screened and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][Tf 2 N]) was found to have the maximum solubility and favoured for enzymatic activity of freeze dried mycelia. The whole-cell catalyzed synthesis of caffeic acid phenethyl ester (CAPE) conditions were optimized and bioconversion up to 84% was achieved at a substrate molar ratio of 1:20 (caffeic acid:2-phenyl ethanol), 30°C for 12h. Results obtained during this study were encouraging and helpful to design a bioreactor system to produce caffeic acid derived esters. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Phytochemical profile of Orthosiphon aristatus extracts after storage: Rosmarinic acid and other caffeic acid derivatives.

    Science.gov (United States)

    Chua, Lee Suan; Lau, Cher Haan; Chew, Chee Yung; Ismail, Nurul Izzati Mohd; Soontorngun, Nitnipa

    2018-01-15

    Orthosiphon aristatus (Blume) Miq. is a medicinal herb which is traditionally used for the treatment of diabetes and kidney diseases in South East Asia. Previous studies reported higher concentration of antioxidative phytochemicals, especially rosmarinic acid (ester of caffeic acid) and other caffeic acid derivatives in this plant extract than the other herbs such as rosemary and sage which are usually used as raw materials to produce rosmarinic acid supplement in the market. The phytochemical profile of O. aristatus was investigated at different storage durations for quality comparison. The phytochemicals were extracted from the leaves and stems of O. aristatus using a reflux reactor. The extracts were examined for total phenolic and flavonoid contents, as well as their antioxidant capacities, in terms of radical scavenging, metal chelating and reducing power. The phytochemical profiles were also analyzed by unsupervised principal component analysis and hierarchical cluster analysis, in relation to the factor of storage at 4 °C for 5 weeks. The leaf extract was likely to have more phytochemicals than stem extract, particularly caffeic acid derivatives including glycosylated and alkylated caffeic acids. This explains higher ratio of total phenolic content to total flavonoid content with higher antioxidant capacities for the leaf extracts. Rosmarinic acid dimer and salvianolic acid B appeared to be the major constituents, possibly contributing to the previously reported pharmacological properties. However, the phytochemical profiles were found changing, even though the extracts were stored in the refrigerator (4 °C). The change was significantly observed at the fifth week based on the statistical pattern recognition technique. O. aristatus could be a promising source of rosmarinic acid and its dimer, as well as salvianolic acid B with remarkably antioxidant properties. The phytochemical profile was at least stable for a month stored at 4 °C. It is likely to be

  3. Effects of caffeic and chlorogenic acids on the rat skeletal system.

    Science.gov (United States)

    Folwarczna, J; Pytlik, M; Zych, M; Cegieła, U; Nowinska, B; Kaczmarczyk-Sedlak, I; Sliwinski, L; Trzeciak, H; Trzeciak, H I

    2015-02-01

    Caffeic acid, predominantly as esters linked to quinic acid (chlorogenic acids), is a phenolic acid present at high levels in coffee. The aim of the study was to investigate effects of caffeic and chlorogenic acids on the skeletal system of female rats with normal estrogen levels and estrogen-deficient. Caffeic acid (5 and 50 mg/kg p.o. daily) and chlorogenic acid (100 mg/kg p.o. daily) were administered for 4 weeks to non-ovariectomized and bilaterally ovariectomized mature Wistar rats, and their effects were compared with appropriate controls. Moreover, estradiol (0.2 mg/kg p.o. daily) was administered to ovariectomized rats. Bone turnover markers, mass, mineralization and mechanical properties were examined. Although caffeic acid at a low dose exerted some unfavorable effects on the skeletal system, at high doses, caffeic and chlorogenic acids slightly increased mineralization in the tibia and improved mechanical properties of the femoral diaphysis (compact bone). Unlike estradiol, they did not counteract the worsening of the tibial metaphysis bone strength (cancellous bone) and increases in osteocalcin concentration induced by estrogen deficiency. High doses of the phenolic acids slightly favorably affected the rat skeletal system independently of the estrogen status.

  4. Preparation and characterization of SPION functionalized via caffeic acid

    Energy Technology Data Exchange (ETDEWEB)

    Baykal, A. [Department of Chemistry, Fatih University, B.Çekmece, 34500 Istanbul (Turkey); Amir, Md., E-mail: mda.fatih@gmail.com [Department of Chemistry, Fatih University, B.Çekmece, 34500 Istanbul (Turkey); Günerb, S. [Department of Physics, Fatih University, B.Çekmece, 34500 Istanbul (Turkey); Sözeri, H. [TUBITAK-UME, National Metrology Institute, 41470 Gebze, Kocaeli (Turkey)

    2015-12-01

    Caffeic acid coated superparamagnetic iron oxide nanoparticles (SPION-CFA) was synthesized by reflux method. The structural, spectroscopic and magnetic properties were studied by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), and Vibrating sample magnetometer (VSM) techniques. Thermal gravimetric analysis (TG) and Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of CA on the surface of SPION. The theoretical analyzes performed on recorded room temperature VSM spectrum confirmed the formation of superparamagnetic nature of SPION-CFA. The particle size dependent Langevin function was applied to determine the average magnetic particle dimension (D{sub mag}) around 11.93 nm. In accordance, the average crystallite and particle sizes were obtained as 11.40 nm and ~12.00 nm from XRD and TEM measurements. The extrapolated specific saturation magnetization (σ{sub s}) is 44.11 emu/g and measured magnetic moment is 1.83 µ{sub B}. These parameters assign small order of magnetization for NPs with respect to bulk Fe{sub 3}O{sub 4}. Magnetic anisotropy was offered as uniaxial and calculated effective anisotropy constant (K{sub eff}) is 34.82×10{sup 4} Erg/g. The size-dependent saturation magnetization suggests the existence of a magnetically inactive layer as 1.035 nm for SPION-CFA. - Highlights: • The effects of CFA on the microstructure and magnetic properties of SPION have been investigated. • Product was structurally and magnetically characterized. • Product presented superparamagnetic behavior at room temperature.

  5. Nanomolar Caffeic Acid Decreases Glucose Uptake and the Effects of High Glucose in Endothelial Cells.

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    Lucia Natarelli

    Full Text Available Epidemiological studies suggest that moderate and prolonged consumption of coffee is associated with a reduced risk of developing type 2 diabetes but the molecular mechanisms underlying this effect are not known. In this study, we report the effects of physiological concentrations of caffeic acid, easily achievable by normal dietary habits, in endothelial cells cultured in 25 mM of glucose (high glucose, HG. In HG, the presence of 10 nM caffeic acid was associated with a decrease of glucose uptake but not to changes of GLUT-1 membrane localization or mRNA levels. Moreover, caffeic acid countered HG-induced loss of barrier integrity, reducing actin rearrangement and FITC-dextran passage. The decreased flux of glucose associated to caffeic acid affected HG induced apoptosis by down-regulating the expression of initiator (caspase 8 and 9 and effector caspases (caspase 7 and 3 and by increasing the levels of phosphorylated Bcl-2. We also observed that caffeic acid in HG condition was associated to a reduction of p65 subunit nuclear levels with respect to HG alone. NF-κB activation has been shown to lead to apoptosis in HG treated cells and the analysis of the expression of a panel of about 90 genes related to NF-κB signaling pathway revealed that caffeic acid significantly influenced gene expression changes induced by HG. In conclusion, our results suggest that caffeic acid, decreasing the metabolic stress induced by HG, allows the activation of survival mechanisms mediated by a different modulation of NF-κB-related signaling pathways and to the activation of anti-apoptotic proteins.

  6. Biosynthesis of caffeic acid in Escherichia coli using its endogenous hydroxylase complex

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    Lin Yuheng

    2012-04-01

    Full Text Available Abstract Background Caffeic acid (3,4-dihydroxycinnamic acid is a natural phenolic compound derived from the plant phenylpropanoid pathway. Caffeic acid and its phenethyl ester (CAPE have attracted increasing attention for their various pharmaceutical properties and health-promoting effects. Nowadays, large-scale production of drugs or drug precursors via microbial approaches provides a promising alternative to chemical synthesis and extraction from plant sources. Results We first identified that an Escherichia coli native hydroxylase complex previously characterized as the 4-hydroxyphenylacetate 3-hydroxylase (4HPA3H was able to convert p-coumaric acid to caffeic acid efficiently. This critical enzymatic step catalyzed in plants by a membrane-associated cytochrome P450 enzyme, p-coumarate 3-hydroxylase (C3H, is difficult to be functionally expressed in prokaryotic systems. Moreover, the performances of two tyrosine ammonia lyases (TALs from Rhodobacter species were compared after overexpression in E. coli. The results indicated that the TAL from R. capsulatus (Rc possesses higher activity towards both tyrosine and L-dopa. Based on these findings, we further designed a dual pathway leading from tyrosine to caffeic acid consisting of the enzymes 4HPA3H and RcTAL. This heterologous pathway extended E. coli native tyrosine biosynthesis machinery and was able to produce caffeic acid (12.1 mg/L in minimal salt medium. Further improvement in production was accomplished by boosting tyrosine biosynthesis in E. coli, which involved the alleviation of tyrosine-induced feedback inhibition and carbon flux redirection. Finally, the titer of caffeic acid reached 50.2 mg/L in shake flasks after 48-hour cultivation. Conclusion We have successfully established a novel pathway and constructed an E. coli strain for the production of caffeic acid. This work forms a basis for further improvement in production, as well as opens the possibility of microbial synthesis

  7. Quantification of caffeic acid content in 4 species of mullein (Verbascum sp. ecotypes from southwest Iran

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    F. Jamshidi kia

    2017-11-01

    Full Text Available Background and objectives: The Verbascum genus is the largest genus of Scrophulariaceae family which has extensive natural habitat in southwest of Iran. Phenolic acids are one of the most important chemical compounds that have different biological activities including anti-inflammatory, antibacterial, antiviral, anti-tumor and antioxidant. Therefore, this study was conducted with the aim of caffeic acid quantification of 4 species of Verbascum sp. ecotypes from southwest Iran. Methods: Nine ecotypes of the 4 species (V. macrophyllus, V. pseudo- digitalis, V. sinatum, V. songaricum were collected from the southwest of Iran. Quantification of caffeic acid contentusing reversed-phase high-performance liquid chromatography (RP-HPLC with UV PDA 2800 detector, a C18 column with dimensions of 250×4.6 mm was performed. Results: The results showed that Verbascum sp. contained caffeic acid compound and there was a difference among species and ecotypes. The results showed the highest and lowest content of caffeic acid obtained from the V. sinatum species and ecotype Sepidan (7.76 μg/mg extract and V. songaricum species and ecotype Farokhshahr (0.54 μg/mg extract, respectively. Conclusion: The results revealed a high level of variation in caffeic acid among Verbascum sp. which was affected by habitat and climatic. The pattern of habitats of suitable ecotypes superior in terms of composition to should be selected and used for breeding and cropping mullein.

  8. Activity of caffeic acid in different fish lipid matrices: A review

    DEFF Research Database (Denmark)

    Medina, Isabel; Undeland, Ingrid; Larsson, Karin

    2012-01-01

    that the antioxidant activity depends on the physical state of the lipids and the composition of the intrinsic matrix in which they are situated. Caffeic acid significantly prevented rancidity in both unwashed and washed fish mince, the latter which was fortified with haemoglobin. In the unwashed mince, the activity......Caffeic acid, a hydroxycinnamic acid common in different vegetable sources, has been employed as a natural antioxidant for inhibiting oxidation of fish lipids present in different food matrices. The aim of this review is to discuss the mechanisms involved in the antioxidative and prooxidative...... effects of caffeic acid found in different model systems containing fish lipids. These model systems include bulk fish oils, liposomes from cod roe phospholipids, fish oil emulsions, washed cod mince, regular horse mackerel mince and a fish oil fortified fitness bar. The data reported show...

  9. [Determination of chlorogenic acid, caffeic acid and linarin in Flos Chrysanthemi Indici from different places by RP-hPLC].

    Science.gov (United States)

    Guo, Qiaosheng; Fang, Hailing; Shen, Haijin

    2010-05-01

    To evaluate the quality of Flos Chrysanthemi Indici which produced in twenty-two different producing places. Chlorogenic acid and caffeic acid were analyzed on a Shim-pack C8 colunm (4.6 mm x 250 mm, 5 microm) eluted with the mobile phase consisted of acetonitrile-0.5% phosphoric acid( 19:81). The detection wavelength was set at 326 nm. Linarin were eluted with the mobile phase consisted of methanol-water-acetic acid(26: 23: 1). The detection wavelength was set at 334 nm. The column temperature was 25 degrees C. The flow rate was 1.0 mL x min . The linear response ranged within 2.5-50 microg for chlorogenic acid (r = 0.998), 2.5-25 microg for caffeic acid (r = 0.998) and 4.97-41.47 microg for linarin (r = 0.999), respectively. Recoveries were 100.8% with RSD 2.1% for chlorogenic acid, 96.2% with RSD 2.3% for caffeic acid and 103.7% with RSD 1.8% for linarin. There was a significant difference in the content of chlorogenic acid, caffeic acid, linarin among the samples. The content of chlorogenic in the sample from Fengdou Chongqing city was the highest in those from other places. The content of caffeic acid in the all samples is very low. The content of linarin in the samples from Jiangsu province and Anhui province almost reached the national standard in pharmacopoeia.

  10. The timing of caffeic acid treatment with cisplatin determines sensitization or resistance of ovarian carcinoma cell lines

    Directory of Open Access Journals (Sweden)

    R. Sirota

    2017-04-01

    The use of caffeic acid as adjuvant for cisplatin should be carefully examined due to different pharmacokinetic profiles of caffeic acid and cisplatin. Thus, it is questionable if the two agents can reach the tumors at the right time frame in vivo.

  11. Caffeic acid as active principle from the fruit of Xanthium strumarium to lower plasma glucose in diabetic rats.

    Science.gov (United States)

    Hsu, F L; Chen, Y C; Cheng, J T

    2000-04-01

    The antihyperglycemic effect of caffeic acid, one of the phenolic compounds contained in the fruit of Xanthium strumarium, was investigated. After an intravenous injection of caffeic acid into diabetic rats of both streptozotocin-induced and insulin-resistant models, a dose-dependent decrease of plasma glucose was observed. However, a similar effect was not produced in normal rats. An insulin-independent action of caffeic acid can thus be considered. Otherwise, this compound reduced the elevation of plasma glucose level in insulin-resistant rats receiving a glucose challenge test. Also, glucose uptake into the isolated adipocytes was raised by caffeic acid in a concentration-dependent manner. Increase of glucose utilization by caffeic acid seems to be responsible for the lowering of plasma glucose.

  12. Antimicrobial and enhancement of the antibiotic activity by phenolic compounds: Gallic acid, caffeic acid and pyrogallol.

    Science.gov (United States)

    Lima, Valéria N; Oliveira-Tintino, Cícera D M; Santos, Enaide S; Morais, Luís P; Tintino, Saulo R; Freitas, Thiago S; Geraldo, Yuri S; Pereira, Raimundo L S; Cruz, Rafael P; Menezes, Irwin R A; Coutinho, Henrique D M

    2016-10-01

    The indiscriminate use of antimicrobial drugs has increased the spectrum of exposure of these organisms. In our studies, these phenolic compounds were evaluated: gallic acid, caffeic acid and pyrogallol. The antibacterial, antifungal and modulatory of antibiotic activities of these compounds were assayed using microdilution method of Minimum Inhibitory Concentration (MIC) to bacteria and Minimum Fungicide Concentration (MFC) to fungi. The modulation was made by comparisons of the MIC and MFC of the compounds alone and combined with drugs against bacteria and fungi respectively, using a sub-inhibitory concentration of 128 μg/mL of substances (MIC/8). All substances not demonstrated clinically relevant antibacterial activity with a MIC above ≥1024 μg/mL. As a result, we observed that the caffeic acid presented a potentiating antibacterial effect over the 3 groups of bacteria studied. Pyrogallol showed a synergistic effect with two of the antibiotics tested, but only against Staphylococcus aureus. In general, caffeic acid was the substance that presented with the greatest number of antibiotics and with the greatest number of bacteria. In relation to the antifungal activity of all the compounds, the verified results were ≥1024 μg/mL, not demonstrating significant activity. Regarding potentiation of the effect of fluconazole, was observed synergistic effect only when assayed against Candida tropicalis, with all substances. Therefore, as can be seen, the compounds presented as substances that can be promising potentiating agents of antimicrobial drugs, even though they do not have direct antibacterial and antifungal action. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Determination of caffeic acid in root and rhizome of Black cohosh (Cimicifuga racemosa (L. Nutt.

    Directory of Open Access Journals (Sweden)

    Zapala Karolina

    2014-06-01

    Full Text Available Cimicifuga racemosa, is a plant with a diverse and long history of medicinal use. Caffeic acid, bioactive compound, which often occurs with other polyphenols can influence the biological activity of this plant. The aim of our work was quantitative analysis of caffeic acid in roots and rhizomes of two varieties of C. racemosa. Analysis was performed by HPLC method. The extracts were separated on C18 reversed-phase column using mixture of methanol, water and formic acid (25:75:0.5 v/v/v as a mobile phase. The flow rate of eluent was 1.0 ml·min-1. The obtained validation parameters such as linearity, linear regression equation and precision expressed as a relative standard deviation were adequate for quantitative determination. Caffeic acid was found in all tested extracts. The highest total amount of caffeic acid was determined in C. racemosa var. racemosa (255.3 μg·g-1 while its concentration in C. racemosa var. cordifolia was significantly lower (213.0 μg·g-1.

  14. Mechanism and kinetics in reactions of caffeic acid with radicals by pulse radiolysis and calculation

    International Nuclear Information System (INIS)

    Li, Xifeng; Cai, Zhongli; Katsumura, Yosuke

    2000-01-01

    The interaction of caffeic acid with e aq - , (CH 3 ) 2 (OH) CCH 2 · , CO 2 ·- , H · , ·OH and N 3 · radicals were studied by γ-, pulse radiolysis and molecular orbital calculation. UV-visible spectra of electron/·OH adducts, semi-quinone radicals of caffeic ions, and the stable products from the reactions were derived. The rate constants were determined. The attacked sites and the most favorable structures of the transient radicals were predicted. Reaction mechanisms were proposed. (author)

  15. HIGH PERFORMANCE THIN LAYER CHROMATOGRAPHIC DETERMINATION OF CAFFEIC ACID AND ROSMARINIC ACID FROM THE LEAVES OF Orthosiphon stamineus

    Directory of Open Access Journals (Sweden)

    M. Amzad Hossain

    2010-06-01

    Full Text Available This paper presents the studies performed on extraction of Orthosiphon stamineus, Benth by using different solvent for the identification and quantification of the caffeic acid derivatives such as caffeic acid  and rosmarinic acid which confers to the leaves of this plant with remarkable pharmaceutical properties. High performance thin-layer chromatographic (HPTLC allows the identification and the quantification of more than 20 samples in the same chromatographic run. The analysis of the samples requires 15-30 min compared with more than 2 h using a typical HPLC method. Using the techniques of the HPTLC and the UV-VIS spectra we have found that the extraction of this herb plant contain, the caffeic acid and rosmarinic acid ranging between 0.029% up to 0.506% and up to 0.24% to 2.24% respectively.     Keywords: Caffice acid derivatives, quantification, Malaysian Orthosiphon stamineus, HPTLC

  16. Chitosan-caffeic acid-genipin films presenting enhanced antioxidant activity and stability in acidic media.

    Science.gov (United States)

    Nunes, Cláudia; Maricato, Élia; Cunha, Ângela; Nunes, Alexandra; da Silva, José A Lopes; Coimbra, Manuel A

    2013-01-02

    The use of chitosan films has been limited due to their high degradability in aqueous acidic media. In order to produce chitosan films with high antioxidant activity and insoluble in acid solutions caffeic acid was grafted to chitosan by a radical mechanism using ammonium cerium (IV) nitrate (60 mM). Genipin was used as cross-linker. This methodology originated films with 80% higher antioxidant activity than the pristine film. Also, these films only lost 11% of their mass upon seven days immersion into an aqueous solution at pH 3.5 under stirring. The films surface wettability (contact angle 105°), mechanical properties (68 MPa of tensile strength and 4% of elongation at break), and thermal stability for temperatures lower than 300 °C were not significantly influenced by the covalent linkage of caffeic acid and genipin to chitosan. Due to their characteristics, mainly higher antioxidant activity and lower solubility, these are promising materials to be used as active films. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Effect of high pressure on peanut allergens in the presence of polyphenol oxidase and caffeic acid

    Science.gov (United States)

    High pressure (HP) enhances enzymatic reactions. Because polyphenol oxidase (PPO) is an enzyme, and reduces IgE binding of peanut allergens in presence of caffeic acid (CA), we postulated that a further reduction in IgE binding can be achieved, using HP together with PPO and CA. Peanut extracts cont...

  18. Inhibitory Effects of Caffeic Acid, a Coffee-Related Organic Acid, on the Propagation of Hepatitis C Virus.

    Science.gov (United States)

    Tanida, Isei; Shirasago, Yoshitaka; Suzuki, Ryosuke; Abe, Ryo; Wakita, Takaji; Hanada, Kentaro; Fukasawa, Masayoshi

    2015-01-01

    Multipurpose cohort studies have demonstrated that coffee consumption reduces the risk of hepatocellular carcinoma (HCC). Given that one of the main causes of HCC is hepatitis C virus (HCV) infection, we examined the effect of caffeic acid, a major organic acid derived from coffee, on the propagation of HCV using an in vitro naïve HCV particle-infection and production system within human hepatoma-derived Huh-7.5.1-8 cells. When cells were treated with 1% coffee extract or 0.1% caffeic acid for 1-h post HCV infection, the amount of HCV particles released into the medium at 3 and 4 days post-infection considerably decreased. In addition, HCV-infected cells cultured with 0.001% caffeic acid for 4 days, also released less HCV particles into the medium. Caffeic acid treatment inhibited the initial stage of HCV infection (i.e., between virion entry and the translation of the RNA genome) in both HCV genotypes 1b and 2a. These results suggest that the treatment of cells with caffeic acid may inhibit HCV propagation.

  19. Biotechnological production of caffeic acid derivatives from cell and organ cultures of Echinacea species.

    Science.gov (United States)

    Murthy, Hosakatte Niranjana; Kim, Yun-Soo; Park, So-Young; Paek, Kee-Yoeup

    2014-09-01

    Caffeic acid derivatives (CADs) are a group of bioactive compounds which are produced in Echinacea species especially Echinacea purpurea, Echinacea angustifolia, and Echinacea pallida. Echinacea is a popular herbal medicine used in the treatment of common cold and it is also a prominent dietary supplement used throughout the world. Caffeic acid, chlorogenic acid (5-O-caffeoylquinic acid), caftaric acid (2-O-caffeoyltartaric acid), cichoric acid (2, 3-O-dicaffeoyltartaric acid), cynarin, and echinacoside are some of the important CADs which have varied pharmacological activities. The concentrations of these bioactive compounds are species specific and also they vary considerably with the cultivated Echinacea species due to geographical location, stage of development, time of harvest, and growth conditions. Due to these reasons, plant cell and organ cultures have become attractive alternative for the production of biomass and caffeic acid derivatives. Adventitious and hairy roots have been induced in E. pupurea and E. angustifolia, and suspension cultures have been established from flask to bioreactor scale for the production of biomass and CADs. Tremendous progress has been made in this area; various bioprocess methods and strategies have been developed for constant high-quality productivity of biomass and secondary products. This review is aimed to discuss biotechnological methods and approaches employed for the sustainable production of CADs.

  20. Design, synthesis, and evaluation of caffeic acid amides as synergists to sensitize fluconazole-resistant Candida albicans to fluconazole.

    Science.gov (United States)

    Dai, Li; Zang, Chengxu; Tian, Shujuan; Liu, Wei; Tan, Shanlun; Cai, Zhan; Ni, Tingjunhong; An, Maomao; Li, Ran; Gao, Yue; Zhang, Dazhi; Jiang, Yuanying

    2015-01-01

    A series of caffeic acid amides were designed, synthesized, and their synergistic activity with fluconazole against fluconazole-resistant Candida albicans was evaluated in vitro. The title caffeic acid amides 3-30 except 26 exhibited potent activity, and the subsequent SAR study was conducted. Compound 3, 5, 21, and 34c, at a concentration of 1.0 μg/ml, decreased the MIC₈₀ of fluconazole from 128.0 μg/ml to 1.0-0.5 μg/ml against the fluconazole-resistant C. albicans. This result suggests that the caffeic acid amides, as synergists, can sensitize drug-resistant fungi to fluconazole. The SAR study indicated that the dihydroxyl groups and the amido groups linking to phenyl or heterocyclic rings are the important pharmacophores of the caffeic acid amides.

  1. Antioxidative effect of lipophilized caffeic acid in fish oil enriched mayonnaise and milk.

    Science.gov (United States)

    Alemán, Mercedes; Bou, Ricard; Guardiola, Francesc; Durand, Erwann; Villeneuve, Pierre; Jacobsen, Charlotte; Sørensen, Ann-Dorit Moltke

    2015-01-15

    The antioxidative effect of lipophilized caffeic acid was assessed in two different fish oil enriched food products: mayonnaise and milk. In both emulsion systems, caffeic acid esterified with fatty alcohols of different chain lengths (C1-C20) were better antioxidants than the original phenolic compound. The optimal chain length with respect to protection against oxidation was, however, different for the two food systems. Fish oil enriched mayonnaise with caffeates of medium alkyl chain length (butyl, octyl and dodecyl) added resulted in a better oxidative stability than caffeates with shorter (methyl) or longer (octadecyl) alkyl chains. Whereas in fish oil enriched milk emulsions the most effective caffeates were those with shorter alkyl chains (methyl and butyl) rather than the ones with medium and long chains (octyl, dodecyl, hexadecyl and eicosyl). These results demonstrate that there might be an optimum alkyl chain length for each phenolipid in each type of emulsion systems. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Bioavailability of Echinacea Constituents: Caco-2 Monolayers and Pharmacokinetics of the Alkylamides and Caffeic Acid Conjugates

    Directory of Open Access Journals (Sweden)

    R. Lehmann

    2005-10-01

    Full Text Available Many studies have been done over the years to assess the effectiveness of Echinacea as an immunomodulator. We have assessed the potential bioavailability of alkyl- amides and caffeic acid conjugates using Caco-2 monolayers and compared it to their actual bioavailability in a Phase I clinical trial. The caffeic acid conjugates permeated poorly through the Caco-2 monolayers. Alkylamides were found to diffuse rapidly through Caco-2 monolayers. Differences in diffusion rates for each alkylamide correlated to structural variations, with saturation and N-terminal methylation contributing to decreases in diffusion rates. Alkylamide diffusion is not affected by the presence of other constituents and the results for a synthetic alkylamide were in line with those for alkylamides found in an ethanolic Echinacea preparation. We examined plasma from healthy volunteers for 12 hours after ingestion of Echinacea tablets manufactured from an ethanolic liquid extract. Caffeic acid conjugates could not be identified in any plasma sample at any time after tablet ingestion. Alkylamides were detected in plasma 20 minutes after tablet ingestion and for each alkylamide, pharmacokinetic profiles were devised. The data are consistent with the dosing regimen of one tablet three times daily and supports their usage as the primary markers for quality Echinacea preparations.

  3. Combined treatment with caffeic and ferulic acid from Baccharis uncinella C. DC. (Asteraceae) protects against metabolic syndrome in mice.

    Science.gov (United States)

    Bocco, B M; Fernandes, G W; Lorena, F B; Cysneiros, R M; Christoffolete, M A; Grecco, S S; Lancellotti, C L; Romoff, P; Lago, J H G; Bianco, A C; Ribeiro, M O

    2016-03-01

    Fractionation of the EtOH extract from aerial parts of Baccharis uncinella C. DC. (Asteraceae) led to isolation of caffeic and ferulic acids, which were identified from spectroscopic and spectrometric evidence. These compounds exhibit antioxidant and anti-inflammatory properties and have been shown to be effective in the prevention/treatment of metabolic syndrome. This study investigated whether the combined treatment of caffeic and ferulic acids exhibits a more significant beneficial effect in a mouse model with metabolic syndrome. The combination treatment with caffeic and ferulic acids was tested for 60 days in C57 mice kept on a high-fat (40%) diet. The data obtained indicated that treatment with caffeic and ferulic acids prevented gain in body weight induced by the high-fat diet and improved hyperglycemia, hypercholesterolemia and hypertriglyceridemia. The expression of a number of metabolically relevant genes was affected in the liver of these animals, showing that caffeic and ferulic acid treatment results in increased cholesterol uptake and reduced hepatic triglyceride synthesis in the liver, which is a likely explanation for the prevention of hepatic steatosis. In conclusion, the combined treatment of caffeic and ferulic acids displayed major positive effects towards prevention of multiple aspects of the metabolic syndrome and liver steatosis in an obese mouse model.

  4. Mechanism and kinetics in reactions of caffeic acid with radicals by pulse radiolysis and calculation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xifeng; Cai, Zhongli; Katsumura, Yosuke [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab

    2000-03-01

    The interaction of caffeic acid with e{sub aq}{sup -}, (CH{sub 3}){sub 2}(OH) CCH{sub 2}{sup {center_dot}}, CO{sub 2}{sup {center_dot}}{sup -}, H{sup {center_dot}}, {center_dot}OH and N{sub 3}{sup {center_dot}} radicals were studied by {gamma}-, pulse radiolysis and molecular orbital calculation. UV-visible spectra of electron/{center_dot}OH adducts, semi-quinone radicals of caffeic ions, and the stable products from the reactions were derived. The rate constants were determined. The attacked sites and the most favorable structures of the transient radicals were predicted. Reaction mechanisms were proposed. (author)

  5. Antistaphylococcal and biofilm inhibitory activities of gallic, caffeic, and chlorogenic acids.

    Science.gov (United States)

    Luís, Ângelo; Silva, Filomena; Sousa, Sónia; Duarte, Ana Paula; Domingues, Fernanda

    2014-01-01

    Staphylococcus aureus is a Gram-positive pathogen which is able to form biofilms, exhibiting a more pronounced resistance to antibiotics and disinfectants. The hurdles posed in eradicating biofilms have driven the search for new compounds able to fight these structures. Phenolic compounds constitute one of the most numerous and ubiquitous group of plant secondary metabolites with many biological activities. The aim of the present work was to study the potential antimicrobial and antibiofilm properties of gallic, caffeic, and chlorogenic acids against S. aureus as well to elucidate its mechanism of action. It was concluded that the phenolic acids studied in this work have antistaphylococcal properties. For instance, gallic acid is able to influence the adhesion properties of S. aureus. The phenolic acids tested were also able to inhibit the production of α-hemolysin by this microorganism, with the exception of chlorogenic acid. Regarding its mechanism of action, caffeic acid interferes with the stability of the cell membrane and with the metabolic activity of the cells of S. aureus.

  6. Effects of roasting temperatures and gamma irradiation on the content of chlorogenic acid, caffeic acid and soluble carbohydrates of coffee

    International Nuclear Information System (INIS)

    Deshpande, S.N.; Aguilar, A.A.

    1975-01-01

    Two varieties of Puerto Rican coffee, Coffea canephora L. var. Robusta, and Coffea arabica L. var. Borbon, were subjected to four different doses of radiation and roasted at two different temperatures. Aqueous extracts of the ground coffee beans were analyzed for chlorogenic acid and caffeic acid at 324 nm and 360 nm wavelength settings, respectively. Samples subjected to the roasting treatments in conjuction with irradiation treatments were treated with basic lead acetate prior to the colorimetric analyses in order to eliminate interfering substances. The total carbohydrate content was also determined by colorimetric techniques with anthrone reagent. The total nitrogen content of the pulverized samples were determined by the micro-Kjeldahl method. While roasting treatments caused a reduction in the concentrations of the chlorogenic acid, caffeic acid, and the carbohydrates, the radiation treatments increased the concentrations of soluble carbohydrates without affecting the concentrations of chlorogenic acid or caffeic acid. It therefore appears that radiation treatments seem to cause degradation of the acid-polysaccharide complexes liberating soluble sugars. There were no noticable changes in the total content of nitrogen caused by roasting or the radiation treatments as indicated by the statistical analysis employing the split plot design. (author)

  7. The effects of gallic/ferulic/caffeic acids on colour intensification and anthocyanin stability.

    Science.gov (United States)

    Qian, Bing-Jun; Liu, Jian-Hua; Zhao, Shu-Juan; Cai, Jian-Xiong; Jing, Pu

    2017-08-01

    The mechanism by which copigments stabilize colour, by protecting anthocyanin chromophores from nucleophilic attack, seems well accepted. This study was to determine effects of gallic/ferulic/caffeic acids on colour intensification and anthocyanin stability. Molecular dynamics simulations were applied to explore molecular interactions. Phenolic acids intensified the colour by 19%∼27%. Colour fading during heating followed first-order reactions with half-lives of 3.66, 9.64, 3.50, and 3.39h, whereas anthocyanin degradation, determined by the pH differential method (or HPLC-PDA), followed second-order reactions with half-lives of 3.29 (3.40), 3.43 (3.39), 2.29 (0.39), and 2.72 (0.32)h alone or with gallic/ferulic/caffeic acids, respectively, suggesting that anthocyanin degradation was faster than the colour fading. The strongest protection of gallic acids might be attributed to the shortest distance (4.37Å) of its aromatic ring to the anthocyanin (AC) panel. Hyperchromic effects induced by phenolic acids were pronounced and they obscured the accelerated anthocyanin degradation due to self-association interruption. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Chemical Properties of Caffeic and Ferulic Acids in Biological System: Implications in Cancer Therapy. A Review.

    Science.gov (United States)

    Damasceno, Sarah S; Dantas, Bruna B; Ribeiro-Filho, Jaime; Antônio M Araújo, Demetrius; Galberto M da Costa, José

    2017-01-01

    The antioxidant properties of caffeic and ferulic acids in biological systems have been extensively demonstrated. As antioxidants, these compounds prevent the production of reactive oxygen species (ROS), which cause cell lesions that are associated with the development of several diseases, including cancer. Recent findings suggest that the chemoprotective action of these phenolic acids occurs through the following mechanisms: regulation of gene expression, chelation and / or reduction of transition metals, formation of covalent adducts and direct toxicity. The biological efficacy of these promising chemoprotective agents is strongly related with their chemical structure. Therefore, in this study, we discuss the structural characteristics of ferulic and caffeic acids that are responsible for their biological activities, as well as the mechanisms of action involved with the anti-cancer activity. Several reports indicated that the antioxidant effect of these phenylpropanoids results from reactions with free radicals with formation of stable products in the cells. The chelating effect of these compounds was also reported as an important protective mechanism against oxidative. Finally, the lipophilicity of these agents facilitates their entry into the cells, and thus, contributes to the anticancer activity. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  9. Synthesis and Antiradical/Antioxidant Activities of Caffeic Acid Phenethyl Ester and Its Related Propionic, Acetic, and Benzoic Acid Analoguesc

    Directory of Open Access Journals (Sweden)

    Mohamed Touaibia

    2012-12-01

    Full Text Available Caffeic acid phenethyl ester (CAPE is a bioactive component isolated from propolis. A series of CAPE analogues was synthesized and their antiradical/antioxidant effects analyzed. The effect of the presence of the double bond and of the conjugated system on the antioxidant effect is evaluated with the analogues obtained from 3-(3,4-dihydroxyphenyl propanoic acid. Those obtained from 2-(3,4-dihydroxyphenyl acetic acid and 3,4-dihydroxybenzoic acid allow the evaluation of the effect of the presence of two carbons between the carbonyl and aromatic system.

  10. Regulatory Effects of Caffeic Acid Phenethyl Ester on Neuroinflammation in Microglial Cells

    Directory of Open Access Journals (Sweden)

    Cheng-Fang Tsai

    2015-03-01

    Full Text Available Microglial activation has been widely demonstrated to mediate inflammatory processes that are crucial in several neurodegenerative disorders. Pharmaceuticals that can deliver direct inhibitory effects on microglia are therefore considered as a potential strategy to counter balance neurodegenerative progression. Caffeic acid phenethyl ester (CAPE, a natural phenol in honeybee propolis, is known to possess antioxidant, anti-inflammatory and anti-microbial properties. Accordingly, the current study intended to probe the effects of CAPE on microglia activation by using in vitro and in vivo models. Western blot and Griess reaction assay revealed CAPE significantly inhibited the expressions of inducible nitric oxide synthase (NOS, cyclooxygenase (COX-2 and the production of nitric oxide (NO. Administration of CAPE resulted in increased expressions of hemeoxygenase (HO-1and erythropoietin (EPO in microglia. The phosphorylated adenosine monophosphate-activated protein kinase (AMPK-α was further found to regulate the anti-inflammatory effects of caffeic acid. In vivo results from immunohistochemistry along with rotarod test also revealed the anti-neuroinflammatory effects of CAPE in microglia activation. The current study has evidenced several possible molecular determinants, AMPKα, EPO, and HO-1, in mediating anti-neuroinflammatory responses in microglial cells.

  11. Choline chloride-based deep eutectic solvents as additives for optimizing chromatographic behavior of caffeic acid

    International Nuclear Information System (INIS)

    Li, Guizhen; Zhu, Tao; Lei, Yingjie

    2015-01-01

    A series of deep eutectic solvents (DESs) were prepared using glycerol and choline chloride (ChCl), and Fourier transform infrared spectrometer (FT-IR) was used to analyze the spectra of glycerol, choline chloride and DESs based on glycerol and choline chloride. Then DESs were used as the additives of mobile phase to optimize chromatographic behavior of caffeic acid in high performance liquid chromatography (HPLC). A 17-run Box-Behnken design (BBD) was employed to evaluate effect of DESs as additives by analyzing the maximum theoretical plate number. Three factors, reaction temperature (60 .deg. C, 80 .deg. C, 100 .deg. C), molar ratio of glycerol and choline chloride (2 : 1, 3 : 1, 4 : 1, n/n), and volume percent of additives (0.05%, 0.10%, 0.15%, v/v), were investigated in BBD. The optimum experiment condition was that of reaction temperature (80 .deg. C), molar ratio of glycerol and ChCl (3 : 1, n/n), and volume percent of additive (0.10%, v/v). The mean chromatographic theoretical plate number of the caffeic acid this condition was 1567.5, and DESs as additives shorten the retention time and modify the chromatogram shape, proving DESs as additives for effective theoretical plate number and column efficiency in HPLC.

  12. Choline chloride-based deep eutectic solvents as additives for optimizing chromatographic behavior of caffeic acid

    Energy Technology Data Exchange (ETDEWEB)

    Li, Guizhen; Zhu, Tao; Lei, Yingjie [Tianjin University of Technology, Tianjin (China)

    2015-10-15

    A series of deep eutectic solvents (DESs) were prepared using glycerol and choline chloride (ChCl), and Fourier transform infrared spectrometer (FT-IR) was used to analyze the spectra of glycerol, choline chloride and DESs based on glycerol and choline chloride. Then DESs were used as the additives of mobile phase to optimize chromatographic behavior of caffeic acid in high performance liquid chromatography (HPLC). A 17-run Box-Behnken design (BBD) was employed to evaluate effect of DESs as additives by analyzing the maximum theoretical plate number. Three factors, reaction temperature (60 .deg. C, 80 .deg. C, 100 .deg. C), molar ratio of glycerol and choline chloride (2 : 1, 3 : 1, 4 : 1, n/n), and volume percent of additives (0.05%, 0.10%, 0.15%, v/v), were investigated in BBD. The optimum experiment condition was that of reaction temperature (80 .deg. C), molar ratio of glycerol and ChCl (3 : 1, n/n), and volume percent of additive (0.10%, v/v). The mean chromatographic theoretical plate number of the caffeic acid this condition was 1567.5, and DESs as additives shorten the retention time and modify the chromatogram shape, proving DESs as additives for effective theoretical plate number and column efficiency in HPLC.

  13. Thermal transformation of bioactive caffeic acid on fumed silica seen by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry and quantum chemical methods.

    Science.gov (United States)

    Kulik, Tetiana V; Lipkovska, Natalia O; Barvinchenko, Valentyna M; Palyanytsya, Borys B; Kazakova, Olga A; Dudik, Olesia O; Menyhárd, Alfréd; László, Krisztina

    2016-05-15

    Thermochemical studies of hydroxycinnamic acid derivatives and their surface complexes are important for the pharmaceutical industry, medicine and for the development of technologies of heterogeneous biomass pyrolysis. In this study, structural and thermal transformations of caffeic acid complexes on silica surfaces were studied by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry (TPD MS) and quantum chemical methods. Two types of caffeic acid surface complexes are found to form through phenolic or carboxyl groups. The kinetic parameters of the chemical reactions of caffeic acid on silica surface are calculated. The mechanisms of thermal transformations of the caffeic chemisorbed surface complexes are proposed. Thermal decomposition of caffeic acid complex chemisorbed through grafted ester group proceeds via three parallel reactions, producing ketene, vinyl and acetylene derivatives of 1,2-dihydroxybenzene. Immobilization of phenolic acids on the silica surface improves greatly their thermal stability. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Analysis of Caffeic Acid Extraction From Ocimum gratissimum Linn. by High Performance Liquid Chromatography and its Effects on a Cervical Cancer Cell Line

    Directory of Open Access Journals (Sweden)

    Je-Chiuan Ye

    2010-09-01

    Conclusion: This paper shows that high performance liquid chromatography is a suitable analytical method for determining caffeic acid levels in O. gratissimum, Ju ZenTa, and several vegetable oils. Caffeic acid can suppress the proliferation of HeLa cells.

  15. Molecular cloning, characterization and expression of the caffeic acid O-methyltransferase (COMT) ortholog from kenaf (Hibiscus cannabinus)

    Science.gov (United States)

    We cloned the full-length of the gene putatively encoding caffeic acid O-methyltransferase (COMT) from kenaf (Hibiscus cannabinus L.) using degenerate primers and the RACE (rapid amplification of cDNA ends) method. Kenaf is an herbaceous and rapidly growing dicotyledonous plant with great potential ...

  16. Square-wave stripping voltammetric determination of caffeic acid on electrochemically reduced graphene oxide-Nafion composite film.

    Science.gov (United States)

    Filik, Hayati; Çetintaş, Gamze; Avan, Asiye Aslıhan; Aydar, Sevda; Koç, Serkan Naci; Boz, İsmail

    2013-11-15

    An electrochemical sensor composed of Nafion-graphene nanocomposite film for the voltammetric determination of caffeic acid (CA) was studied. A Nafion graphene oxide-modified glassy carbon electrode was fabricated by a simple drop-casting method and then graphene oxide was electrochemically reduced over the glassy carbon electrode. The electrochemical analysis method was based on the adsorption of caffeic acid on Nafion/ER-GO/GCE and then the oxidation of CA during the stripping step. The resulting electrode showed an excellent electrocatalytical response to the oxidation of caffeic acid (CA). The electrochemistry of caffeic acid on Nafion/ER-GO modified glassy carbon electrodes (GCEs) were studied by cyclic voltammetry and square-wave adsorption stripping voltammetry (SW-AdSV). At optimized test conditions, the calibration curve for CA showed two linear segments: the first linear segment increased from 0.1 to 1.5 and second linear segment increased up to 10 µM. The detection limit was determined as 9.1×10(-8) mol L(-1) using SW-AdSV. Finally, the proposed method was successfully used to determine CA in white wine samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Antiviral Properties of Caffeic Acid Phenethyl Ester and Its Potential Application

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    Haci Kemal Erdemli

    2015-12-01

    Full Text Available Caffeic acid phenethyl ester (CAPE is found in variety of plants and well known active ingredient of the honeybee propolis. CAPE showed anti-inflammatory, anticarcinogenic, antimitogenic, antiviral and immunomodulatory properties in several studies. The beneficial effects of CAPE on different health issues attracted scientists to make more studies on CAPE. Specifically, the anti-viral effects of CAPE and its molecular mechanisms may reveal the important properties of virus-induced diseases. CAPE and its targets may have important roles to design new therapeutics and understand the molecular mechanisms of virus related diseases. In this mini-review, we summarize the antiviral effects of CAPE under the light of medical and chemical literature. [J Intercult Ethnopharmacol 2015; 4(4.000: 344-347

  18. Can propolis and caffeic acid phenethyl ester (CAPE be promising agents against cyclophosphamide toxicity?

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    Sumeyya Akyol

    2016-03-01

    Full Text Available Propolis is a mixture having hundreds of polyphenols including caffeic acid phenethyl ester (CAPE. They have been using in several medical conditions/diseases in both in vitro and in vivo experimental setup. Cyclophosphamide has been used to treat a broad of malignancies including Hodgkin’s and non-Hodgking’s lymphoma, Burkitt’s lymphoma, chronic lymphocytic leukemia, Ewing’s sarcoma, breast cancer, testicular cancer, etc. It may cause several side effects after treatment. In this mini review, the protective effects of propolis and CAPE were compared each other in terms of effectiveness against cyclophosphamide-induced injuries. [J Complement Med Res 2016; 5(1.000: 105-107

  19. Effect of caffeic acid phenethyl ester on bone formation in the expanded inter-premaxillary suture

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    Kazancioglu HO

    2015-12-01

    Full Text Available Hakki Oguz Kazancioglu,1 Sertac Aksakalli,2 Seref Ezirganli,1 Muhammet Birlik,2 Mukaddes Esrefoglu,3 Ahmet Hüseyin Acar1 1Department of Oral and Maxillofacial Surgery, 2Department of Orthodontics, Faculty of Dentistry, 3Department of Histology, Faculty of Medicine, Bezmialem Vakif University, Istanbul, Turkey Background: Narrow maxilla is a common problem in orthodontics and dentofacial orthopedics. To solve this problem, a procedure called rapid maxillary expansion (RME has been used. However, relapse tendency is a major problem of RME. Although relapse tendency is not clearly understood, various treatment procedures and new application has been investigated. The present study aimed to investigate the possible effectiveness of caffeic acid phenethyl ester (CAPE on new bone formation in rat midpalatal suture after RME.Materials and methods: Twenty male Sprague Dawley rats were used in this study. The animals were randomly divided into two groups as control and CAPE group. In CAPE group, CAPE was administered systemically via intraperitoneal injection. RME procedure was performed on all animals. For this purpose, the springs were placed on the maxillary incisors of rats and activated for 5 days. After then, the springs were removed and replaced with short lengths of rectangular retaining wire for consolidation period of 15 days. At the end of the study, histomorphometric analysis was carried out to assess of new bone formation.Results: New bone formation was significantly greater in CAPE group than the control group (P<0.05. CAPE enhances new bone formation in midpalatal suture after RME.Conclusion: These results show that CAPE may decrease the time needed for retention. Keywords: rapid maxillary expansion, bone formation, caffeic acid phenethyl ester, midpalatal suture, histopathology

  20. Caffeic Acid-PLGA Conjugate to Design Protein Drug Delivery Systems Stable to Irradiation

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    Francesca Selmin

    2015-01-01

    Full Text Available This work reports the feasibility of caffeic acid grafted PLGA (g-CA-PLGA to design biodegradable sterile microspheres for the delivery of proteins. Ovalbumin (OVA was selected as model compound because of its sensitiveness of γ-radiation. The adopted grafting procedure allowed us to obtain a material with good free radical scavenging properties, without a significant modification of Mw and Tg of the starting PLGA (Mw PLGA = 26.3 ± 1.3 kDa vs. Mw g-CA-PLGA = 22.8 ± 0.7 kDa; Tg PLGA = 47.7 ± 0.8 °C vs. Tg g-CA-PLGA = 47.4 ± 0.2 °C. By using a W1/O/W2 technique, g-CA-PLGA improved the encapsulation efficiency (EE, suggesting that the presence of caffeic residues improved the compatibility between components (EEPLGA = 35.0% ± 0.7% vs. EEg-CA-PLGA = 95.6% ± 2.7%. Microspheres particle size distribution ranged from 15 to 50 µm. The zeta-potential values of placebo and loaded microspheres were −25 mV and −15 mV, respectively. The irradiation of g-CA-PLGA at the dose of 25 kGy caused a less than 1% variation of Mw and the degradation patterns of the non-irradiated and irradiated microspheres were superimposable. The OVA content in g-CA-PLGA microspheres decreased to a lower extent with respect to PLGA microspheres. These results suggest that g-CA-PLGA is a promising biodegradable material to microencapsulate biological drugs.

  1. Sensitive Determination of 6-Thioguanine Using Caffeic Acid-functionalized Fe3O4 Nanoparticles as an Electrochemical Sensor

    Science.gov (United States)

    Amir, Md.; Tunesi, Mawada M.; Soomro, Razium A.; Baykal, Abdülhadi; Kalwar, Nazar H.

    2018-04-01

    The study demonstrates the potential application of caffeic acid-functionalized magnetite nanoparticles (CA-Fe3O4 NPs) as an effective electrode modifying material for the electrochemical oxidation of the 6-thioguanine (6-TG) drug. The functionalized Fe3O4 NPs were prepared using simple wet-chemical methodology where the used caffeic acid acted simultaneously as growth controlling and functionalizing agent. The study discusses the influence of an effective functionalization on the signal sensitivity observed for the electro-oxidation of 6-TG over CA-Fe3O4 NPs in comparison to a glassy carbon electrode modified with bare and nicotinic acid (NA)-functionalized Fe3O4 NPs. The experiment results provided sufficient evidence to support the importance of favorable functionality to achieve higher signal sensitivity for the electro-oxidation of 6-TG. The presence of favorable interactions between the active functional moieties of caffeic acid and 6-TG synergized with the greater surface area of magnetic NPs produces a stable electro-oxidation signal within the working range of 0.01-0.23 μM with sensitive up to 0.001 μM. Additionally, the sensor showed the strong anti-interference potential against the common co-existing drug molecules such as benzoic acid, acetaminophen, epinephrine, norepinephrine, glucose, ascorbic acid and l-cysteine. In addition, the successful quantification of 6-TG from the commercial tablets obtained from local pharmacy further signified the practical capability of the discussed sensor.

  2. Antineurodegenerative effect of phenolic extracts and caffeic acid derivatives in romaine lettuce on neuron-like PC-12 cells.

    Science.gov (United States)

    Im, Sung-Eun; Yoon, Hyungeun; Nam, Tae-Gyu; Heo, Ho Jin; Lee, Chang Yong; Kim, Dae-Ok

    2010-08-01

    In recent decades, romaine lettuce has been one of the fastest growing vegetables with respect to its consumption and production. An understanding is needed of the effect of major phenolic phytochemicals from romaine lettuce on biological protection for neuron-like PC-12 cells. Phenolics in fresh romaine lettuce were extracted, and then its total phenolics and total antioxidant capacity were measured spectrophotometrically. Neuroprotective effects of phenolic extract of romaine lettuce and its pure caffeic acid derivatives (caffeic, chicoric, chlorogenic, and isochlorogenic acids) in PC-12 cells were evaluated using two different in vitro methods: lactate dehydrogenase release and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assays. Total phenolics and total antioxidant capacity of 100 g of fresh romaine lettuce averaged 22.7 mg of gallic acid equivalents and 31.0 mg of vitamin C equivalents, respectively. The phenolic extract of romaine lettuce protected PC-12 cells against oxidative stress caused by H(2)O(2) in a dose-dependent manner. Isochlorogenic acid, one of the phenolics in romaine lettuce, showed stronger neuroprotection than the other three caffeic acid derivatives also found in the lettuce. Although romaine lettuce had lower levels of phenolics and antioxidant capacity compared to other common vegetables, its contribution to total antioxidant capacity and antineurodegenerative effect in human diets would be higher because of higher amounts of its daily per capita consumption compared to other common vegetables.

  3. Effects of caffeic acid phenethyl ester on palatal mucosal defects and tooth extraction sockets

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    Günay A

    2014-10-01

    Full Text Available Ahmet Günay,1 Osman Fatih Arpağ,2 Serhat Atilgan,3 Ferhan Yaman,3 Yusuf Atalay,4 İzzet Acikan3 1Department of Periodontology, Faculty of Dentistry, Dicle University, Diyarbakir, Turkey; 2Department of Periodontology, Faculty of Dentistry, Mustafa Kemal University, Hatay, Turkey; 3Department of Maxillofacial Surgery, Faculty of Dentistry, Dicle University, Diyarbakir, Turkey; 4Department of Maxillofacial Surgery, Faculty of Dentistry, Kocatepe University, Afyon, Turkey Aim: The purpose of this study was to evaluate the effects of caffeic acid phenethyl ester (CAPE on palatal mucosal defects and tooth extraction sockets in an experimental model.Materials and methods: Forty-two male Sprague-Dawley rats with a mean age of 7 weeks and weighing 280–490 g were used in this study. The rats were randomly divided into two groups: group A (the control group, n=21 and group B (the experimental group, n=21. Under anesthesia with ketamine (8 mg/100 g, intraperitoneally, palatal mucosal defects were created and tooth extraction was performed in the rats in groups A and B. Group A received no treatment, whereas group B received CAPE. CAPE was injected daily (10 µmol/kg, intraperitoneally. The rats were killed on days 7, 14, and 30 after the procedures. Palatal mucosa healing and changes in bone tissue and fibrous tissue were evaluated histopathologically.Result: Pairwise comparisons showed no statistically significant difference between days 7 and 14 in either group (P>0.05. At day 30, bone healing was significantly better in group B (CAPE than in group A (control (P<0.05. Fibrinogen levels at day 30 were significantly higher in group A (control than in group B (CAPE (P<0.05. Pairwise comparisons showed no statistically significant difference in palatal mucosa healing levels between days 7 and 14 in both groups (P>0.05.Conclusion: In conclusion, the findings of this study suggest that CAPE can significantly improve tooth socket healing. Keywords: caffeic

  4. Caffeic acid and quercetin exert caspases-independent apoptotic effects on Leishmania major promastigotes, and reactivate the death of infected phagocytes derived from BALB/c mice

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    Radia Belkhelfa-Slimani

    2017-04-01

    Conclusions: The leishmanicidal effect of caffeic acid and quercetin on promastigotes and amastigotes, as well as reactivation of infected phagocytes apoptosis, suggested a potential therapeutic role against cutaneous leishmaniasis.

  5. Chemical evolution. XXI - The amino acids released on hydrolysis of HCN oligomers

    Science.gov (United States)

    Ferris, J. P.; Wos, J. D.; Nooner, D. W.; Oro, J.

    1974-01-01

    Major amino acids released by hydrolysis of acidic and basic HCN oligomers are identified by chromatography as Gly, Asp, and diaminosuccinic acid. Smaller amounts of Ala, Ile and alpha-aminoisobutyric acid are also detected. The amino acids released did not change appreciably when the hydrolysis medium was changed from neutral to acidic or basic. The presence of both meso and d, l-diaminosuccinic acids was established by paper chromatography and on an amino acid analyzer.

  6. Butylated caffeic acid: An efficient novel antioxidant; Ácido cafeico butilado: un nuevo y eficaz antioxidante.

    Energy Technology Data Exchange (ETDEWEB)

    Shi, G.; Liao, X.; Olajide, T.M.; Liu, J.; Jiang, X.; Weng, X.

    2017-07-01

    A novel antioxidant, butylated caffeic acid (BCA) was rationally designed by adding a tert-butyl group to caffeic acid, which was synthesized at a high yield (36.2%) from 2-methoxy-4-methylphenol (1) by a four-step reaction including Friedel-Crafts alkylation, bromine oxidation, ether bond hydrolysis and Knoevenagel condensation. Its antioxidant capacity was much stronger than common commercial antioxidant tert-butyl hydroquinone (TBHQ) and its mother compound, caffeic acid, in both rancimat and deep frying tests. When investigated via the DPPH method, the antioxidant capacity of BCA was almost equal to TBHQ, but lower than caffeic acid. BCA could be a potentially strong antioxidant, especially for food processing at high temperatures such as deep frying and baking. [Spanish] Se diseñó razonadamente un nuevo antioxidante, el ácido cafeico butilado (BCA) mediante la adición de un grupo terc-butilo al ácido cafeico, que se sintetizó con un alto rendimiento (36,2%) a partir de 2-metoxi-4-metilfenol, reacción de Friedel-Crafts, oxidación de bromo, hidrólisis del enlace éter y condensación de Knoevenagel. Su capacidad antioxidante fué mucho más fuerte que la del antioxidante comercial mas común el terc-butil hidroquinona (TBHQ) y la de su compuesto madre el ácido cafeico, tanto en rancimat como en pruebas de fritura. Cuando se investigó mediante el método DPPH, la capacidad antioxidante de BCA fue casi igual a TBHQ, pero menor que la del ácido cafeico. BCA podría ser un fuerte antioxidante potencial, especialmente para el procesamiento de alimentos a alta temperatura, tales como freír y hornear.

  7. Effect of Caffeic Acid Phenethyl Ester on Vascular Damage Caused by Consumption of High Fructose Corn Syrup in Rats

    OpenAIRE

    Gun, Aburrahman; Ozer, Mehmet Kaya; Bilgic, Sedat; Kocaman, Nevin; Ozan, Gonca

    2016-01-01

    Fructose corn syrup is cheap sweetener and prolongs the shelf life of products, but fructose intake causes hyperinsulinemia, hypertriglyceridemia, and hypertension. All of them are referred to as metabolic syndrome and they are risk factors for cardiovascular diseases. Hence, the harmful effects of increased fructose intake on health and their prevention should take greater consideration. Caffeic Acid Phenethyl Ester (CAPE) has beneficial effects on metabolic syndrome and vascular function wh...

  8. Cell killing and radiosensitization by caffeic acid phenethyl ester (CAPE) in lung cancer cells

    International Nuclear Information System (INIS)

    Chen, Miao-Fen; Chen, Wen-Cheng; Wu, Chun-Te; King, P.C.

    2004-01-01

    Caffeic acid phenethyl ester (CAPE) is a biologically active ingredient of honeybee propoplis. The cytotoxicity and radiation sensitization effects of CAPE were evaluated in human lung cancer A549 cells and normal lung fibroblast WI-38 cells. A549 cells treated with 6 μg/ml CAPE showed marked growth inhibition (60%) at 48 hr after treatments. During the same time, the number of viable cells decreased to 46% of the control value. In contrast, WI-38 cells showed 20% growth inhibition with no change in the number of viable cells under the same treatment conditions. At 72 hr after CAPE treatment (6 μg/ml), the percentage of apoptotic cells in A549 cultures increased significantly to 67% and an S/G2 arrest was also detected in the culture. Furthermore, there was a significant decrease in the level of intracellular glutathione and hydrogen peroxide contents within one hr after CAPE treatment, and the expression of cyclin B 1 was reduced 6 hr after treatment. The radiation sensitization effect of CAPE on A549 cells was determined from the clonogenic survival curves, and the results showed a small but significant difference in radiation survival between cells treated with or without CAPE. Taken together, our results suggest that the effects of CAPE on differential cytotoxicity, apoptosis, and radiosensitization are associated with glutathione depletion that occurred shortly after treatments. (author)

  9. Protective Effects of Intralipid and Caffeic Acid Phenethyl Ester on Nephrotoxicity Caused by Dichlorvos in Rats

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    Muhammet Murat Celik

    2015-01-01

    Full Text Available The protective effects of Caffeic Acid Phenethyl Ester (CAPE and intralipid (IL on nephrotoxicity caused by acute Dichlorvos (D toxicity were investigated in this study. Forty-eight Wistar Albino rats were divided into 7 groups as follows: Control, D, CAPE, intralipid, D + CAPE, D + IL, and D + CAPE + IL. When compared to D group, the oxidative stress index (OSI values were significantly lower in Control, CAPE, and D + IL + CAPE groups. When compared to D + IL + CAPE group, the TOS and OSI values were significantly higher in D group (P<0.05. When mitotic cell counts were assessed in the renal tissues, it was found that mitotic cell count was significantly higher in the D group while it was lower in the D + CAPE, D + IL, and D + IL + CAPE groups when compared to the control group (P<0.05. Also, immune reactivity showed increased apoptosis in D group and low profile of apoptosis in the D + CAPE group when compared to the Control group. The apoptosis level was significantly lower in D + IL + CAPE compared to D group (P<0.05 in the kidneys. As a result, we concluded that Dichlorvos can be used either alone or in combination with CAPE and IL as supportive therapy or as facilitator for the therapeutic effect of the routine treatment in the patients presenting with pesticide poisoning.

  10. Effects of caffeic acid phenethyl ester on palatal mucosal defects and tooth extraction sockets

    Science.gov (United States)

    Günay, Ahmet; Arpağ, Osman Fatih; Atilgan, Serhat; Yaman, Ferhan; Atalay, Yusuf; Acikan, İzzet

    2014-01-01

    Aim The purpose of this study was to evaluate the effects of caffeic acid phenethyl ester (CAPE) on palatal mucosal defects and tooth extraction sockets in an experimental model. Materials and methods Forty-two male Sprague-Dawley rats with a mean age of 7 weeks and weighing 280–490 g were used in this study. The rats were randomly divided into two groups: group A (the control group, n=21) and group B (the experimental group, n=21). Under anesthesia with ketamine (8 mg/100 g, intraperitoneally), palatal mucosal defects were created and tooth extraction was performed in the rats in groups A and B. Group A received no treatment, whereas group B received CAPE. CAPE was injected daily (10 μmol/kg, intraperitoneally). The rats were killed on days 7, 14, and 30 after the procedures. Palatal mucosa healing and changes in bone tissue and fibrous tissue were evaluated histopathologically. Result Pairwise comparisons showed no statistically significant difference between days 7 and 14 in either group (P>0.05). At day 30, bone healing was significantly better in group B (CAPE) than in group A (control) (P0.05). Conclusion In conclusion, the findings of this study suggest that CAPE can significantly improve tooth socket healing. PMID:25364232

  11. Modulation of Tamoxifen Cytotoxicity by Caffeic Acid Phenethyl Ester in MCF-7 Breast Cancer Cells

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    Tarek K. Motawi

    2016-01-01

    Full Text Available Although Tamoxifen (TAM is one of the most widely used drugs in managing breast cancer, many women still relapse after long-term therapy. Caffeic acid phenethyl ester (CAPE is a polyphenolic compound present in many medicinal plants and in propolis. The present study examined the effect of CAPE on TAM cytotoxicity in MCF-7 cells. MCF-7 cells were treated with different concentrations of TAM and/or CAPE for 48 h. This novel combination exerted synergistic cytotoxic effects against MCF-7 cells via induction of apoptotic machinery with activation of caspases and DNA fragmentation, along with downregulation of Bcl-2 and Beclin 1 expression levels. However, the mammalian microtubule-associated protein light chain LC 3-II level was unchanged. Vascular endothelial growth factor level was also decreased, whereas levels of glutathione and nitric oxide were increased. In conclusion, CAPE augmented TAM cytotoxicity via multiple mechanisms, providing a novel therapeutic approach for breast cancer treatment that can overcome resistance and lower toxicity. This effect provides a rationale for further investigation of this combination.

  12. Early Treatment of radiation-Induced Heart Damage in Rats by Caffeic acid phenethyl Ester

    International Nuclear Information System (INIS)

    Tawfik, S.S.; Mansour, H. H.

    2012-12-01

    The study designed to determine the therapeutic effect of caffeic acid phenethyl ester (CAPE) in minimising radiation-induced injuries in rats. Rats were exposed to 7 Gy γ-rays, 30 minutes later; rats were injected with CAPE (10μmol/ kg body, i.p.) for 7 consecutive days. Rats were sacrificed at 8 and 15 days after starting the experiment. Gamma-irradiation induced significant increase in malonaldehyde (MDA) level and xanthine oxidase (XO) and adenosine deaminase (ADA) activities, and significant decrease in total nitrate/nitrate (NO (x)) level and glutathione peroxidise (Gpx), superoxide dismutase (SOD)and catalase (CAT) activities in heart tissue and augmented activities of lactate dehydrogenase (LDH), creatine phosphokinase (CPK) and aspartate transaminase (AST) in serum. Irradiated rats early treated with CAPE showed significant decrease in MDA, XO and ADA and significant increase in group. Cardiac enzymes were restored. Conclusion, CAPE could exhibits curable effect on gamma irradiation-induced cardiac-oxidative impairment in rats. (Author)

  13. Phenolic Profiling of Caffeic Acid O-Methyltransferase-Deficient Poplar Reveals Novel Benzodioxane Oligolignols1

    Science.gov (United States)

    Morreel, Kris; Ralph, John; Lu, Fachuang; Goeminne, Geert; Busson, Roger; Herdewijn, Piet; Goeman, Jan L.; Van der Eycken, Johan; Boerjan, Wout; Messens, Eric

    2004-01-01

    Caffeic acid O-methyltransferase (COMT) catalyzes preferentially the methylation of 5-hydroxyconiferaldehyde to sinapaldehyde in monolignol biosynthesis. Here, we have compared HPLC profiles of the methanol-soluble phenolics fraction of xylem tissue from COMT-deficient and control poplars (Populus spp.), using statistical analysis of the peak heights. COMT down-regulation results in significant concentration differences for 25 of the 91 analyzed peaks. Eight peaks were exclusively detected in COMT-deficient poplar, of which four could be purified for further identification using mass spectrometry/mass spectrometry, nuclear magnetic resonance, and spiking of synthesized reference compounds. These new compounds were derived from 5-hydroxyconiferyl alcohol or 5-hydroxyconiferaldehyde and were characterized by benzodioxane moieties, a structural type that is also increased in the lignins of COMT-deficient plants. One of these four benzodioxanes amounted to the most abundant oligolignol in the HPLC profile. Furthermore, all of the differentially accumulating oligolignols involving sinapyl units were either reduced in abundance or undetectable. The concentration levels of all identified oligolignols were in agreement with the relative supply of monolignols and with their chemical coupling propensities, which supports the random coupling hypothesis. Chiral HPLC analysis of the most abundant benzodioxane dimer revealed the presence of both enantiomers in equal amounts, indicating that they were formed by radical coupling reactions under simple chemical control rather than guided by dirigent proteins. PMID:15563622

  14. Phenolic profiling of caffeic acid O-methyltransferase-deficient poplar reveals novel benzodioxane oligolignols.

    Science.gov (United States)

    Morreel, Kris; Ralph, John; Lu, Fachuang; Goeminne, Geert; Busson, Roger; Herdewijn, Piet; Goeman, Jan L; Van der Eycken, Johan; Boerjan, Wout; Messens, Eric

    2004-12-01

    Caffeic acid O-methyltransferase (COMT) catalyzes preferentially the methylation of 5-hydroxyconiferaldehyde to sinapaldehyde in monolignol biosynthesis. Here, we have compared HPLC profiles of the methanol-soluble phenolics fraction of xylem tissue from COMT-deficient and control poplars (Populus spp.), using statistical analysis of the peak heights. COMT down-regulation results in significant concentration differences for 25 of the 91 analyzed peaks. Eight peaks were exclusively detected in COMT-deficient poplar, of which four could be purified for further identification using mass spectrometry/mass spectrometry, nuclear magnetic resonance, and spiking of synthesized reference compounds. These new compounds were derived from 5-hydroxyconiferyl alcohol or 5-hydroxyconiferaldehyde and were characterized by benzodioxane moieties, a structural type that is also increased in the lignins of COMT-deficient plants. One of these four benzodioxanes amounted to the most abundant oligolignol in the HPLC profile. Furthermore, all of the differentially accumulating oligolignols involving sinapyl units were either reduced in abundance or undetectable. The concentration levels of all identified oligolignols were in agreement with the relative supply of monolignols and with their chemical coupling propensities, which supports the random coupling hypothesis. Chiral HPLC analysis of the most abundant benzodioxane dimer revealed the presence of both enantiomers in equal amounts, indicating that they were formed by radical coupling reactions under simple chemical control rather than guided by dirigent proteins.

  15. Caffeic Acid Phenethyl Ester Is a Potential Therapeutic Agent for Oral Cancer

    Directory of Open Access Journals (Sweden)

    Ying-Yu Kuo

    2015-05-01

    Full Text Available Head and neck cancers, which affect 650,000 people and cause 350,000 deaths per year, is the sixth leading cancer by cancer incidence and eighth by cancer-related death worldwide. Oral cancer is the most common type of head and neck cancer. More than 90% of oral cancers are oral and oropharyngeal squamous cell carcinoma (OSCC. The overall five-year survival rate of OSCC patients is approximately 63%, which is due to the low response rate to current therapeutic drugs. In this review we discuss the possibility of using caffeic acid phenethyl ester (CAPE as an alternative treatment for oral cancer. CAPE is a strong antioxidant extracted from honeybee hive propolis. Recent studies indicate that CAPE treatment can effectively suppress the proliferation, survival, and metastasis of oral cancer cells. CAPE treatment inhibits Akt signaling, cell cycle regulatory proteins, NF-κB function, as well as activity of matrix metalloproteinase (MMPs, epidermal growth factor receptor (EGFR, and Cyclooxygenase-2 (COX-2. Therefore, CAPE treatment induces cell cycle arrest and apoptosis in oral cancer cells. According to the evidence that aberrations in the EGFR/phosphoinositide 3-kinase (PI3K/protein kinase B (Akt signaling, NF-κB function, COX-2 activity, and MMPs activity are frequently found in oral cancers, and that the phosphorylation of Akt, EGFR, and COX-2 correlates to oral cancer patient survival and clinical progression, we believe that CAPE treatment will be useful for treatment of advanced oral cancer patients.

  16. EFFECTS OF EXERCISE AND CAFFEIC ACID PHENETHYL ESTER AFTER CHRONIC EXERCISE RAT MODEL

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    Ayse Alp

    2011-01-01

    Full Text Available In order to understand whether exercise and caffeic acid phenethyl ester (CAPE has an effect on obesity and weight control, we investigated the effects of CAPE, and exercise on lipid parameters (triglyceride, total cholesterol, HDL-C, LDL-C, and adipokine substances such as leptin and resistin in rats. 40 male rat were randomly assigned into 4 groups. It was determined that CAPE does not have any significant effect on these parameters but that lipid parameters and leptin values in exercise groups decreased considerably, while no significant change occurred in resistin levels. In order to understand whether diet has an effect on exercise, body weights of all animal groups in pre and post-exercise were compared. A significant weight gain was observed (p = 0.005 in all groups. This study concluded that exercise has a considerable effect on leptin and lipid parameters; however, exercise alone was not sufficient for weight control and could be effective in weight control only when accompanied by a restricted diet.

  17. Studies on Oligomer Metal Complexes Derived from Bisamic Acid of Pyromellitic Dianhydride and 4-Bromoaniline.

    Science.gov (United States)

    Patel, Yogesh S

    2014-01-01

    Novel oligomer metal complexes (2a-f) of the ligand 2,5-bis((4-bromophenyl)carbamoyl) terephthalic acid (1) were prepared using transition metal salts and characterized by various spectroscopic techniques. The geometry of oligomer metal complexes was carried out by electronic spectral analysis and magnetic measurement studies. Polymeric properties have also been carried out. Ligand was synthesized using pyromellitic dianhydride and 4-bromoaniline. It was duly characterized. All novel synthesized compounds 1 and 2a-f were evaluated for their antibacterial and antifungal activity. The results showed significantly higher antibacterial and antifungal activity of oligomer metal complexes compared to the ligand.

  18. Studies on Oligomer Metal Complexes Derived from Bisamic Acid of Pyromellitic Dianhydride and 4-Bromoaniline

    OpenAIRE

    Patel, Yogesh S.

    2014-01-01

    Novel oligomer metal complexes (2a–f) of the ligand 2,5-bis((4-bromophenyl)carbamoyl) terephthalic acid (1) were prepared using transition metal salts and characterized by various spectroscopic techniques. The geometry of oligomer metal complexes was carried out by electronic spectral analysis and magnetic measurement studies. Polymeric properties have also been carried out. Ligand was synthesized using pyromellitic dianhydride and 4-bromoaniline. It was duly characterized. All novel synthesi...

  19. Caffeic acid, tyrosol and p-coumaric acid are potent inhibitors of 5-S-cysteinyl-dopamine induced neurotoxicity.

    Science.gov (United States)

    Vauzour, David; Corona, Giulia; Spencer, Jeremy P E

    2010-09-01

    Parkinson's disease is characterized by a progressive and selective loss of dopaminergic neurons in the substantia nigra. Recent investigations have shown that conjugates such as the 5-S-cysteinyl-dopamine, possess strong neurotoxicity and may contribute to the underlying progression of the disease pathology. Although the neuroprotective actions of flavonoids are well reported, that of hydroxycinnamates and other phenolic acids is less established. We show that the hydroxycinnamates caffeic acid and p-coumaric acid, the hydroxyphenethyl alcohol, tyrosol, and a Champagne wine extract rich in these components protect neurons against injury induced by 5-S-cysteinyl-dopamine in vitro. The protection induced by these polyphenols was equal to or greater than that observed for the flavonoids, (+)-catechin, (-)-epicatechin and quercetin. For example, p-coumaric acid evoked significantly more protection at 1muM (64.0+/-3.1%) than both (-)-epicatechin (46.0+/-4.1%, p<0.05) and (+)-catechin (13.1+/-3.0%, p<0.001) at the same concentration. These data indicate that hydroxycinnamates, phenolic acids and phenolic alcohol are also capable of inducing neuroprotective effects to a similar extent to that seen with flavonoids. Copyright © 2010. Published by Elsevier Inc.

  20. Restorative Effects of Caffeic Acid Phenethyl Ester in Radiation-Induced Oxidative Hepatic Disorders

    International Nuclear Information System (INIS)

    El-Fatih, N.M.; EI-Tawil, G.A.

    2009-01-01

    The potential role of antioxidant natural phenolic compounds in the prevention of oxidative tissue-damage associated with ionizing-radiation has accumulated over the past decades. The possible restorative effect of caffeic acid phenethyl ester (CAPE) in minimizing radiation-induced hepatic injury in male albino rats was investigated. CAPE was given to rats via intraperitoneal (ip.) injection at a dose of (10μmol/ kg b.wt.) for 21 successive days throughout exposure to gamma radiation and continued for 15 successive days post gamma-radiation exposure. Whole body gamma-irradiation was delivered as fractionated doses (3 weeks) 2 Gy increment every week up to total cumulative dose of G Gy. Rats were sacrificed at either I, or 15 days after last dose of radiation. Malondialdehyde (MDA) content was determined in plasma and hepatic tissues. In addition, the activities of xanthine oxidase (XO), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) as well as the level of reduced glutathione (GSH) were determined to evaluate the changes of antioxidant-status in blood systems and hepatic tissues. Meantime, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) activities were estimated in rat serum. Results showed that exposure to gamma-radiation significantly increased the MDA levels and the activities of XO, ALT, AST and ALP. Moreover, SOD, CAT and GSH-Px activities as well GSH contents showed significant consumption in irradiated rats. Treatment with CAPE showed a significant decrease in MDA level and caused significant increases in all enzymes measured in hepatic tissues and blood systems when compared with irradiated group. Conclusion: radiation-exposure leads to a reduction in antioxidant enzymatic activities and causes lipid peroxidation in hepatic tissues and blood. Under experimental condition, CAPE exhibits restorative effects on gamma-rays-induced hepatic-oxidative impairment in rats

  1. Restorative Effects of Caffeic Acid Phenethyl Ester in Radiation-Induced Oxidative Hepatic Disorders

    International Nuclear Information System (INIS)

    El-Fatih, N.M.; EI-Tawil, G.A.

    2008-01-01

    The potential role of antioxidant natural phenolic compounds in the prevention of oxidative tissue-damage associated with ionizing-radiation has accumulated over the past decades. The possible restorative effect of caffeic acid phenethyl ester (CAPE) in minimizing radiation-induced hepatic injury in male albino rats was investigated. CAPE was given to rats via intraperitoneal (ip.) injection at a dose of (10μmol/ kg b.wt.) for 21 successive days throughout exposure to gamma radiation and continued for 15 successive days post gamma-radiation exposure. Whole body gamma-irradiation was delivered as fractionated doses (3 weeks) 2 Gy increment every week up to total cumulative dose of G Gy. Rats were sacrificed at either I, or 15 days after last dose of radiation. Malondialdehyde (MDA) content was determined in plasma and hepatic tissues. In addition, the activities of xanthine oxidase (XO), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) as well as the level of reduced glutathione (GSH) were determined to evaluate the changes of antioxidant-status in blood systems and hepatic tissues. Meantime, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) activities were estimated in rat serum. Results showed that exposure to gamma-radiation significantly increased the MDA levels and the activities of XO, ALT, AST and ALP. Moreover, SOD, CAT and GSH-Px activities as well GSH contents showed significant consumption in irradiated rats. Treatment with CAPE showed a significant decrease in MDA level and caused significant increases in all enzymes measured in hepatic tissues and blood systems when compared with irradiated group. Conclusion: radiation-exposure leads to a reduction in antioxidant enzymatic activities and causes lipid peroxidation in hepatic tissues and blood. Under experimental condition, CAPE exhibits restorative effects on gamma-rays-induced hepatic-oxidative impairment in rats

  2. Potential Effects of Caffeic Acid in Suppression of Matrix Metalloproteinases Activities in Irradiated Rats

    International Nuclear Information System (INIS)

    Zahran, A.M.

    2008-01-01

    Great Number of researches on the potential role of antioxidant nutrients and phenolic compounds in the prevention of chronic diseases has been accumulated over the past several decades. Despite this effort, there is much that remains uncertain. Bio markers research in this field has the potential to help fill the gaps in current knowledge. The present study was designed to evaluate, in one aspect, the probable direction expression of proteolytic enzymes as indices for gamma-irradiation-induced oxidative stress and their relationship, in other aspect with one antioxidant micro nutrient phenolic compound: caffeic acid (CA). Sprague Dawley male albino rats were administrated CA intraperitoneally (i.p.) 10 μmol/ kg body wt/ day for 8 consecutive days pre irradiation exposure (fractionated doses, instalment as 1 Gy every day up to total dose of 8 Gy). The treatment was continued for 15 successive days following irradiation processing. Quantitative assay of gelatinolytic zymo graphic analysis of serum and hepatic tissues showed that exposure to gamma-rays yields a marked significant increase in the activities of both latent and active MMP-9 (92 and 86 kDa), respectively, and both latent and active MMP-2 (72 and 66 kDa), respectively. Administration of CA significantly decreased the activities of MMP-2 and MMP-9 in gamma-irradiated rats. Conclusion: the present findings demonstrated that irradiation-exposure leads to enhancement of enzymatic activities of MMP-2 and MMP-9 in their inactive and active forms in the serum and liver. Meanwhile, administration of CA exhibits protective effects in gamma-irradiated rats through down-regulation of MMP-2 and MMP-9 activities

  3. Effect of antioxidant activity of caffeic acid with cyclodextrins using ground mixture method

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    Ryota Shiozawa

    2018-01-01

    Full Text Available In the current study, we prepared a ground mixture (GM of caffeic acid (CA with α-cyclodextrin (αCD and with β-cyclodextrin (βCD, and then comparatively assessed the physicochemical properties and antioxidant capacities of these GMs. Phase solubility diagrams indicated that both CA/αCD and CA/βCD formed a complex at a molar ratio of 1/1. In addition, stability constants suggested that CA was more stable inside the cavity of αCD than inside the cavity of βCD. Results of powder X-ray diffraction (PXRD indicated that the characteristic diffraction peaks of CA and CD disappeared and a halo pattern was produced by the GMs of CA/αCD and CA/βCD (molar ratios = 1/1. Dissolution testing revealed that both GMs had a higher rate of dissolution than CA alone did. Based on the 1H-1H NOESY NMR spectra for the GM of CA/αCD, the vinylene group of the CA molecule appeared to be included from the wider to the narrower rim of the αCD ring. Based on spectra for the GM of CA/βCD, the aromatic ring of the CA molecule appeared to be included from the wider to the narrower rim of the βCD ring. This suggests that the structures of the CA inclusion complexes differed between those involving αCD rings and those involving βCD rings. Results of a DPPH radical-scavenging activity test indicated that the GM of CA/αCD had a higher antioxidant capacity than that of the GM of CA/βCD. The differences in the antioxidant capacities of the GMs of CA/αCD and CA/βCD are presumably due to differences in stability constants and structures of the inclusion complexes.

  4. Genomic study of the absorption mechanism of p-coumaric acid and caffeic acid of extract of Ananas comosus L. leaves.

    Science.gov (United States)

    Dang, Yun-jie; Zhu, Chun-yan

    2015-03-01

    Cardiac disease has emerged as the leading cause of death worldwide, and food rich in phenolic acids has drawn much attention as sources of active substances of hypolipidemic drug. Ananas comosus L. (pineapple) is one of the most popular tropical and subtropical fruits. Isolated from pineapple leaves, EAL(Extract of Ananas Comosus L. Leaves) is rich in phenolic acids, such as p-coumaric acid, caffeic acid, and other phenolics, highly relevant to the putative cardiovascular-protective effects, which suggests its potential to be a new plant medicine for treatment of cardiac disease, but little is known about absorption, distribution, metabolism, and excretion of EAL in animals or human beings. In this study, we employed cDNA microarray, Caco-2 cell lines, and rat intestinal model to explore the absorption behavior of p-coumaric acid and caffeic acid in EAL. The permeation of 2 substances was concentration and time dependent. Results also indicated that monocarboxylic acid transporter was involved in the transepithelial transport of p-coumaric acid and caffeic acid. © 2015 Institute of Food Technologists®

  5. Anti-inflammatory and anti-coagulatory activities of caffeic acid and ellagic acid in cardiac tissue of diabetic mice

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    Hsu Cheng-chin

    2009-08-01

    Full Text Available Abstract Background Caffeic acid (CA and ellagic acid (EA are phenolic acids naturally occurring in many plant foods. Cardiac protective effects of these compounds against dyslipidemia, hypercoagulability, oxidative stress and inflammation in diabetic mice were examined. Methods Diabetic mice were divided into three groups (15 mice per group: diabetic mice with normal diet, 2% CA treatment, or 2% EA treatment. One group of non-diabetic mice with normal diet was used for comparison. After 12 weeks supplement, mice were sacrificed, and the variation of biomarkers for hypercoagulability, oxidative stress and inflammation in cardiac tissue of diabetic mice were measured. Results The intake of CA or EA significantly increased cardiac content of these compounds, alleviated body weight loss, elevated plasma insulin and decreased plasma glucose levels in diabetic mice (p p p p p p p Conclusion These results support that CA and EA could provide triglyceride-lowering, anti-coagulatory, anti-oxidative, and anti-inflammatory protection in cardiac tissue of diabetic mice. Thus, the supplement of these agents might be helpful for the prevention or attenuation of diabetic cardiomyopathy.

  6. α-Synuclein oligomers induced by docosahexaenoic acid affect membrane integrity.

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    Chiara Fecchio

    Full Text Available A key feature of Parkinson disease is the aggregation of α-synuclein and its intracellular deposition in fibrillar form. Increasing evidence suggests that the pathogenicity of α-synuclein is correlated with the activity of oligomers formed in the early stages of its aggregation process. Oligomers toxicity seems to be associated with both their ability to bind and affect the integrity of lipid membranes. Previously, we demonstrated that α-synuclein forms oligomeric species in the presence of docosahexaenoic acid and that these species are toxic to cells. Here we studied how interaction of these oligomers with membranes results in cell toxicity, using cellular membrane-mimetic and cell model systems. We found that α-synuclein oligomers are able to interact with large and small unilamellar negatively charged vesicles acquiring an increased amount of α-helical structure, which induces small molecules release. We explored the possibility that oligomers effects on membranes could be due to pore formation, to a detergent-like effect or to fibril growth on the membrane. Our biophysical and cellular findings are consistent with a model where α-synuclein oligomers are embedded into the lipid bilayer causing transient alteration of membrane permeability.

  7. Development of an Electrochemical Sensor for NADH Determination Based on a Caffeic Acid Redox Mediator Supported on Carbon Black

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    Chiara Zanardi

    2015-04-01

    Full Text Available Screen-printed electrode (SPE modified with carbon black nanoparticles (CB has been tested as a new platform for the stable deposition of caffeic acid (CFA on the electrode surface. The electrochemical performance from varying the amount of CFA/CB composite has been tested with respect to NADH determination. The electrocatalytic activity of CFA/CB has also been compared with that of SPEs modified by a single component of the coating, i.e., either CFA or CB. Finally, glycerol dehydrogenase, a typical NADH-dependent enzyme, was deposited on the CFA/CB coating in order to test the applicability of the sensor in glycerol determination.

  8. Improved Stability of Tuberculosis Drug Fixed-Dose Combination Using Isoniazid-Caffeic Acid and Vanillic Acid Cocrystal.

    Science.gov (United States)

    Battini, Swapna; Mannava, M K Chaitanya; Nangia, Ashwini

    2018-06-01

    The classic fixed-dose combination (FDC) of 4 tuberculosis drugs, namely rifampicin (RIF), isoniazid (INH), pyrazinamide (PZA), and ethambutol dihydrochloride (EDH) has the twin issues of physical stability and RIF cross-reaction in the 4-FDC. The major reason for these quality issues is the interaction between RIF and INH to yield isonicotinyl hydrazone in drug tablets. Pharmaceutical cocrystals of INH with caffeic acid (CFA) (PZA + EDH + RIF + INH-CFA cocrystal) and vanillic acid (VLA) (PZA + EDH + RIF + INH-VLA cocrystal) are able to stabilize the FDC formulation compared with the reference batch (PZA + EDH + RIF + INH). Stability studies under accelerated humidity and temperature stress conditions of 40°C and 75% relative humidity showed that the physical stability of the cocrystal formulation was superior by powder X-ray diffraction and scanning electron microscopy analysis, and chemical purity was analyzed by high-performance liquid chromatography. Changes in the composition and structure were monitored on samples drawn at 7, 15, 22, and 30 days of storage. FDC-INH-CFA cocrystal batch exhibited greater stability compared with FDC-INH-VLA cocrystal and FDC reference drug batches. The superior stability of INH-CFA cocrystal is attributed to the presence of stronger hydrogen bonds and cyclic O-H⋯O synthon in the crystal structure. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  9. Caffeic acid phenethyl ester prevents cadmium-induced cardiac impairment in rat

    International Nuclear Information System (INIS)

    Mollaoglu, Hakan; Gokcimen, Alpaslan; Ozguner, Fehmi; Oktem, Faruk; Koyu, Ahmet; Kocak, Ahmet; Demirin, Hilmi; Gokalp, Osman; Cicek, Ekrem

    2006-01-01

    Caffeic acid phenethyl ester (CAPE), a flavonoid like compound, is one of the major components of honeybee propolis. It was found to be a potent free radical scavenger and antioxidant recently. The aim of this study was to examine the effect of CAPE on cadmium (Cd)-induced hypertension and cardiomyopathy in rats. In particular, nitric oxide (NO) may contribute to the pathophysiology of Cd induced cardiac impairment. Malondialdehyde (MDA, an index of lipid peroxidation) levels and nitric oxide (NO, a vasodilator) levels were used as markers Cd-induced cardiac impairment and the success of CAPE treatment. Also, the findings have been supported by the histopathologic evidences. The rats were randomly divided into three experimental groups each (12), as follows: the control group, Cd-treated group (Cd) and Cd plus CAPE-treated group (Cd + CAPE). CdCl 2 in 0.9% NaCl was administrated intraperitoneally (i.p.) with a dose of 1 mg/kg/day. CAPE was co-administered i.p. a dose of 10 μM/kg for 15 days. Hypertension was found to be induced by intraperitoneal administration of Cd in a dose of 1 mg/kg/day on the measurements taken 15 days later. MDA levels were increased (p < 0.001) in cardiac tissue and NO levels were decreased (p < 0.05) in serum in the Cd group than those of the control group had. On the other hand, there was a slight difference (increase) in MDA levels in the Cd + CAPE group than the ones in the control group (p < 0.003). In addition, MDA levels were decreased and NO levels were increased in the Cd + CAPE group compared with the Cd group (p < 0.001, p < 0.0001, respectively). As a result, treatment with CAPE significantly reversed the increased lipid peroxidation (LPO) product, MDA, and decreased NO levels in Cd treated animals. In the histopathologic examination, a significant hypertrophy in atrial and ventricular myofibrils was observed in only Cd administered group, in comparison with the control group. There was no statistically significant difference

  10. Is caffeic acid phenethyl ester more protective than doxycycline in experimental periodontitis?

    Science.gov (United States)

    Yiğit, Umut; Kırzıoğlu, Fatma Yeşim; Uğuz, Abdülhadi Cihangir; Nazıroğlu, Mustafa; Özmen, Özlem

    2017-09-01

    Host modulation therapies (anti-inflammatory drugs, bone-stimulating agents, anti-proteinase etc.) target the inhibition or stabilization of tissue breakdown. The aim of the present study was to evaluate the effects of caffeic acid phenethyl ester (CAPE) and/or low dose doxycycline (LDD) administrations on alveolar bone loss (ABL), serum cytokines and gingival apoptosis, as well as the levels of oxidants and anti-oxidants in rats with ligature-induced periodontitis. The animals were randomly divided into five groups: Group C (periodontally healthy), Group PC (Periodontitis+CAPE), Group PD (Periodontitis+LDD), Group PCD (Periodontitis+CAPE+LDD), Group P (Periodontitis). Experimental periodontitis was induced for 14days. Levels of ABL, and the serum cytokines, interleukin (IL)-1 β, IL-6, tumor necrosis factor-α (TNF-α) and IL-10 were assessed as were the levels of the oxidants and anti-oxidants, malondialdehyde (MDA), glutathione (GSH) and glutathione peroxidase (GSH-Px), and levels of gingival apoptosis. The lowest ABL levels was evident in the PC group, among the experimental groups. There was also less inflammatory infiltration in the PC group than the PD group. IL-1β, IL-6, and IL-10 were lower in the PC group and higher in the P group in comparison to the levels in the other experiment groups. TNF-α levels in the PD group were higher than levels in the PC and PCD groups. The PC and PCD groups did not differ from the C group in regard to MDA levels. The highest GSH-Px level was found in the PC group. Gingival apoptosis in the PC group was not only lower than the PD and PCD groups, but also lower than in the C group. The present study suggests that CAPE has more anti-inflammatory, anti-oxidant and anti-apoptotic effects than LDD, with no additive benefits of a CAPE+LDD combination being evident in rats with periodontitis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. A Comparative Study of the Radical-scavenging Activity of the Phenolcarboxylic Acids Caffeic Acid, p-Coumaric Acid, Chlorogenic Acid and Ferulic Acid, With or Without 2-Mercaptoethanol, a Thiol, Using the Induction Period Method

    Directory of Open Access Journals (Sweden)

    Seiichiro Fujisawa

    2008-10-01

    Full Text Available Phenolcarboxylic acid antioxidants do not act in vivo as radical-scavengers in isolation, but rather together with GSH (glutathione, a coantioxidant, they constitute an intricate antioxidant network. Caffeic acid, p-coumaric acid, ferulic acid and chlorogenic acid with or without 2-mercaptoethanol (ME, as a substitute for GSH, was investigated by the induction period (IP method for polymerization of methyl methacrylate (MMA initiated by thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN, a source of alkyl radicals, R. and benzoyl peroxide (BPO, a source of peroxy radicals, PhCOO. using differential scanning calorimetry (DSC. Upon PhCOO. radical scavenging, the stoichiometric factors (n, number of free radical trapped by one mole of antioxidant for caffeic acid, ferulic acid, p-coumaric acid and chlorogenic acid were 2.4, 1.8, 1.7 and 0.9, whereas upon R. radical scavenging, the corresponding values were 1.3, 1.2, 1.0 and 0.8, respectively. Antioxidants with n values close to 2 suggest the stepwise formation of semiquinone radicals and quinones. By contrast, those with n values close to 1 suggest the formation of dimers after single-electron oxidation, possibly due to recombination of corresponding aryloxy radicals. The ratio of the rate constant of inhibition to that of propagation (kinh/kp declined in the order chlorogenic acid > p-coumaric acid > ferulic acid > caffeic acid. The ratio of the observed IP for the phenolcarboxylic acid/2-mercapto-ethanol (ME mixture (1:1 molar ratio (A to the calculated IP (the simple sum of phenol acid antioxidant and ME (B was investigated. Upon R. scavenging, the caffeic acid or p-coumaric acid/ME mixture was A/B > 1, particularly the former was 1.2, suggesting a synergic effect. By contrast, upon PhCOO. scavenging, the corresponding mixture was A/B < 1, particularly the latter was 0.7, suggesting an antagonistic effect. Upon both radicals scavenging, the A/B for the ferulic acid or chlorogenic acid

  12. Modulation of phenytoin teratogenicity and embryonic covalent binding by acetylsalicylic acid, caffeic acid, and alpha-phenyl-N-t-butylnitrone: implications for bioactivation by prostaglandin synthetase

    International Nuclear Information System (INIS)

    Wells, P.G.; Zubovits, J.T.; Wong, S.T.; Molinari, L.M.; Ali, S.

    1989-01-01

    Teratogenicity of the anticonvulsant drug phenytoin is thought to involve its bioactivation by cytochromes P-450 to a reactive arene oxide intermediate. We hypothesized that phenytoin also may be bioactivated to a teratogenic free radical intermediate by another enzymatic system, prostaglandin synthetase. To evaluate the teratogenic contribution of this latter pathway, an irreversible inhibitor of prostaglandin synthetase, acetylsalicylic acid (ASA), 10 mg/kg intraperitoneally (ip), was administered to pregnant CD-1 mice at 9:00 AM on Gestational Days 12 and 13, 2 hr before phenytoin, 65 mg/kg ip. Other groups were pretreated 2 hr prior to phenytoin administration with either the antioxidant caffeic acid or the free radical spin trapping agent alpha-phenyl-N-t-butylnitrone (PBN). Caffeic acid and PBN were given ip in doses that respectively were up to 1.0 to 0.05 molar equivalents to the dose of phenytoin. Dams were killed on Day 19 and the fetuses were assessed for teratologic anomalies. A similar study evaluated the effect of ASA on the in vivo covalent binding of radiolabeled phenytoin administered on Day 12, in which case dams were killed 24 hr later on Day 13. ASA pretreatment produced a 50% reduction in the incidence of fetal cleft palates induced by phenytoin (p less than 0.05), without significantly altering the incidence of resorptions or mean fetal body weight. Pretreatment with either caffeic acid or PBN resulted in dose-related decreases in the incidence of fetal cleft palates produced by phenytoin, with maximal respective reductions of 71 and 82% at the highest doses of caffeic acid and PBN (p less than 0.05)

  13. Suppression of skin inflammation in keratinocytes and acute/chronic disease models by caffeic acid phenethyl ester.

    Science.gov (United States)

    Lim, Kyung-Min; Bae, SeungJin; Koo, Jung Eun; Kim, Eun-Sun; Bae, Ok-Nam; Lee, Joo Young

    2015-04-01

    Skin inflammation plays a central role in the pathophysiology and symptoms of diverse chronic skin diseases including atopic dermatitis (AD). In this study, we examined if caffeic acid phenethyl ester (CAPE), a skin-permeable bioactive compound from propolis, was protective against skin inflammation using in vitro cell system and in vivo animal disease models. CAPE suppressed TNF-α-induced NF-κB activation and expression of inflammatory cytokines in human keratinocytes (HaCaT). The potency and efficacy of CAPE were superior to those of a non-phenethyl derivative, caffeic acid. Consistently, topical treatment of CAPE (0.5 %) attenuated 12-O-tetradecanoylphorbol-13-acetate(TPA)-induced skin inflammation on mouse ear as CAPE reduced ear swelling and histologic inflammation scores. CAPE suppressed increased expression of pro-inflammatory molecules such as TNF-α, cyclooxygenase-2 and inducible NO synthase in TPA-stimulated skin. TPA-induced phosphorylation of IκB and ERK was blocked by CAPE suggesting that protective effects of CAPE on skin inflammation is attributed to inhibition of NF-κB activation. Most importantly, in an oxazolone-induced chronic dermatitis model, topical application of CAPE (0.5 and 1 %) was effective in alleviating AD-like symptoms such as increases of trans-epidermal water loss, skin thickening and serum IgE as well as histologic inflammation assessment. Collectively, our results propose CAPE as a promising candidate for a novel topical drug for skin inflammatory diseases.

  14. Reduction of the DNA damages, Hepatoprotective Effect and Antioxidant Potential of the Coconut Water, ascorbic and Caffeic Acids in Oxidative Stress Mediated by Ethanol

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    VANDERSON S. BISPO

    Full Text Available ABSTRACT Hepatic disorders such as steatosis and alcoholic steatohepatitis are common diseases that affect thousands of people around the globe. This study aims to identify the main phenol compounds using a new HPLC-ESI+-MS/MS method, to evaluate some oxidative stress parameters and the hepatoprotective action of green dwarf coconut water, caffeic and ascorbic acids on the liver and serum of rats treated with ethanol. The results showed five polyphenols in the lyophilized coconut water spiked with standards: chlorogenic acid (0.18 µM, caffeic acid (1.1 µM, methyl caffeate (0.03 µM, quercetin (0.08 µM and ferulic acid (0.02 µM isomers. In the animals, the activity of the serum γ-glutamyltranspeptidase (γ-GT was reduced to 1.8 I.U/L in the coconut water group, 3.6 I.U/L in the ascorbic acid group and 2.9 I.U/L in the caffeic acid groups, when compared with the ethanol group (5.1 I.U/L, p<0.05. Still in liver, the DNA analysis demonstrated a decrease of oxidized bases compared to ethanol group of 36.2% and 48.0% for pretreated and post treated coconut water group respectively, 42.5% for the caffeic acid group, and 34.5% for the ascorbic acid group. The ascorbic acid was efficient in inhibiting the thiobarbituric acid reactive substances (TBARS in the liver by 16.5% in comparison with the ethanol group. These data indicate that the green dwarf coconut water, caffeic and ascorbic acids have antioxidant, hepatoprotective and reduced DNA damage properties, thus decreasing the oxidative stress induced by ethanol metabolism.

  15. A simple procedure for preparing chitin oligomers through acetone precipitation after hydrolysis in concentrated hydrochloric acid.

    Science.gov (United States)

    Kazami, Nao; Sakaguchi, Masayoshi; Mizutani, Daisuke; Masuda, Tatsuhiko; Wakita, Satoshi; Oyama, Fumitaka; Kawakita, Masao; Sugahara, Yasusato

    2015-11-05

    Chitin oligomers are of interest because of their numerous biologically relevant properties. To prepare chitin oligomers containing 4-6 GlcNAc units [(GlcNAc)4-6], α- and β-chitin were hydrolyzed with concentrated hydrochloric acid at 40 °C. The reactant was mixed with acetone to recover the acetone-insoluble material, and (GlcNAc)4-6 was efficiently recovered after subsequent water extraction. Composition analysis using gel permeation chromatography and MALDI-TOF mass spectrometry indicated that (GlcNAc)4-6 could be isolated from the acetone-insoluble material with recoveries of approximately 17% and 21% from the starting α-chitin and β-chitin, respectively. The acetone precipitation method is highly useful for recovering chitin oligomers from the acid hydrolysate of chitin. The changes in the molecular size and higher-order structure of chitin during the course of hydrolysis were also analyzed, and a model that explains the process of oligomer accumulation is proposed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Size-Dependent Affinity of Glycine and Its Short Oligomers to Pyrite Surface: A Model for Prebiotic Accumulation of Amino Acid Oligomers on a Mineral Surface

    Science.gov (United States)

    Afrin, Rehana; Ganbaatar, Narangerel; Aono, Masashi; Cleaves, H. James; Yano, Taka-aki; Hara, Masahiko

    2018-01-01

    The interaction strength of progressively longer oligomers of glycine, (Gly), di-Gly, tri-Gly, and penta-Gly, with a natural pyrite surface was directly measured using the force mode of an atomic force microscope (AFM). In recent years, selective activation of abiotically formed amino acids on mineral surfaces, especially that of pyrite, has been proposed as an important step in many origins of life scenarios. To investigate such notions, we used AFM-based force measurements to probe possible non-covalent interactions between pyrite and amino acids, starting from the simplest amino acid, Gly. Although Gly itself interacted with the pyrite surface only weakly, progressively larger unbinding forces and binding frequencies were obtained using oligomers from di-Gly to penta-Gly. In addition to an expected increase of the configurational entropy and size-dependent van der Waals force, the increasing number of polar peptide bonds, among others, may be responsible for this observation. The effect of chain length was also investigated by performing similar experiments using l-lysine vs. poly-l-lysine (PLL), and l-glutamic acid vs. poly-l-glutamic acid. The results suggest that longer oligomers/polymers of amino acids can be preferentially adsorbed on pyrite surfaces. PMID:29370126

  17. Caffeic Acid Phenethyl Ester as a Protective Agent against Nephrotoxicity and/or Oxidative Kidney Damage: A Detailed Systematic Review

    Directory of Open Access Journals (Sweden)

    Sumeyya Akyol

    2014-01-01

    Full Text Available Caffeic acid phenethyl ester (CAPE, an active component of propolis, has been attracting the attention of different medical and pharmaceutical disciplines in recent years because of its antioxidant, anti-inflammatory, antiproliferative, cytotoxic, antiviral, antifungal, and antineoplastic properties. One of the most studied organs for the effects of CAPE is the kidney, particularly in the capacity of this ester to decrease the nephrotoxicity induced by several drugs and the oxidative injury after ischemia/reperfusion (I/R. In this review, we summarized and critically evaluated the current knowledge regarding the protective effect of CAPE in nephrotoxicity induced by several special medicines such as cisplatin, doxorubicin, cyclosporine, gentamycin, methotrexate, and other causes leading to oxidative renal injury, namely, I/R models and senility.

  18. Caffeic acid phenethyl ester as a remedial agent for reproductive functions and oxidative stress-based pathologies of gonads.

    Science.gov (United States)

    Akyol, Sumeyya; Akbas, Ali; Butun, Ilknur; Toktas, Muhsin; Ozyurt, Huseyin; Sahin, Semsettin; Akyol, Omer

    2015-01-01

    In recent years, the studies on the roles of caffeic acid phenethyl ester (CAPE) in several disease models and cell cultures are tremendously growing. It is such a great molecule that was used by ancient times to ameliorate some diseases and nowadays, it is used by modern medicine to test the effectiveness. In this mini-review article, the protection capability of CAPE, as a liposoluble antioxidant and a potent nuclear factor kappa B inhibitor, on oxidative and non-oxidative ovary, and testis damages has been summarized. In view of our laboratory findings/experience and those reported in the hitherto literature, we suggest that CAPE possesses protective effects for pathologies of the reproductive organs induced by untoward effects of harmful molecules such as free oxygen radicals, pesticides, methotrexate, and MK-801 (dizocilpine).

  19. Mechanisms leading to oligomers and SOA through aqueous photooxidation: insights from OH radical oxidation of acetic acid and methylglyoxal

    Directory of Open Access Journals (Sweden)

    Y. Tan

    2012-01-01

    Full Text Available Previous experiments have demonstrated that the aqueous OH radical oxidation of methylglyoxal produces low volatility products including pyruvate, oxalate and oligomers. These products are found predominantly in the particle phase in the atmosphere, suggesting that methylglyoxal is a precursor of secondary organic aerosol (SOA. Acetic acid plays a central role in the aqueous oxidation of methylglyoxal and it is a ubiquitous product of gas phase photochemistry, making it a potential "aqueous" SOA precursor in its own right. However, the fate of acetic acid upon aqueous-phase oxidation is not well understood. In this research, acetic acid (20 μM–10 mM was oxidized by OH radicals, and pyruvic acid and methylglyoxal experimental samples were analyzed using new analytical methods, in order to better understand the formation of SOA from acetic acid and methylglyoxal. Glyoxylic, glycolic, and oxalic acids formed from acetic acid and OH radicals. In contrast to the aqueous OH radical oxidation of methylglyoxal, the aqueous OH radical oxidation of acetic acid did not produce succinic acid and oligomers. This suggests that the methylgloxal-derived oligomers do not form through the acid catalyzed esterification pathway proposed previously. Using results from these experiments, radical mechanisms responsible for oligomer formation from methylglyoxal oxidation in clouds and wet aerosols are proposed. The importance of acetic acid/acetate as an SOA precursor is also discussed. We hypothesize that this and similar chemistry is central to the daytime formation of oligomers in wet aerosols.

  20. Evaluation of Chemical Constituents and Antioxidant Activity of Coconut Water (Cocus nucifera L. and Caffeic Acid in Cell Culture

    Directory of Open Access Journals (Sweden)

    JOAO L.A. SANTOS

    2013-09-01

    Full Text Available Coconut water contains several uncharacterized substances and is widely used in the human consumption. In this paper we detected and quantified ascorbic acid and caffeic acid and total phenolics in several varieties of coconut using HPLS/MS/MS (25.8 ± 0.6 µg/mL and 1.078 ± 0.013 µg/mL and 99.7 µg/mL, respectively, in the green dwarf coconut water, or 10 mg and 539 µg and 39.8 mg for units of coconut consumed, 500 ± 50 mL. The antioxidant potential of four coconut varieties (green dwarf, yellow dwarf, red dwarf and yellow Malaysian was compared with two industrialized coconut waters and the lyophilized water of the green dwarf variety. All varieties were effective in scavenging the DPPH radical (IC50=73 µL and oxide nitric (0.1 mL with an IP of 29.9% as well as in inhibiting the in vitro production of thiobarbituric acid reactive substances (1 mL with an IP of 34.4%, highlighting the antioxidant properties of the green dwarf which it is the most common used. In cell culture, the green dwarf water was efficient in protecting against oxidative damages induced by hydrogen peroxide.

  1. Caffeic acid phenethyl ester downregulates phospholipase D1 via direct binding and inhibition of NFκB transactivation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Mi Hee; Kang, Dong Woo [Department of Molecular Biology, Pusan National University, Busan 609-735 (Korea, Republic of); Jung, Yunjin [College of Pharmacy, Pusan National University, Busan 609-735 (Korea, Republic of); Choi, Kang-Yell [Translational Research Center for Protein Function Control, Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul (Korea, Republic of); Min, Do Sik, E-mail: minds@pusan.ac.kr [Department of Molecular Biology, Pusan National University, Busan 609-735 (Korea, Republic of)

    2013-12-06

    Highlights: •We found CAFÉ, a natural product that suppresses expression and activity of PLD1. •CAPE decreased PLD1 expression by inhibiting NFκB transactivation. •CAPE rapidly inhibited PLD activity via its binding to a Cys837 of PLD1. •PLD1 downregulation by CAPE inhibited invasion and proliferation of glioma cells. -- Abstract: Upregulation of phospholipase D (PLD) is functionally linked with oncogenic signals and tumorigenesis. Caffeic acid phenethyl ester (CAPE) is an active compound of propolis extract that exhibits anti-proliferative, anti-inflammatory, anti-oxidant, and antineoplastic properties. In this study, we demonstrated that CAPE suppressed the expression of PLD1 at the transcriptional level via inhibition of binding of NFκB to PLD1 promoter. Moreover, CAPE, but not its analogs, bound to a Cys837 residue of PLD1 and inhibited enzymatic activity of PLD. CAPE also decreased activation of matrix metalloproteinases-2 induced by phosphatidic acid, a product of PLD activity. Ultimately, CAPE-induced downregulation of PLD1 suppressed invasion and proliferation of glioma cells. Taken together, the results of this study indicate that CAPE might contribute to anti-neoplastic effect by targeting PLD1.

  2. Constituents of Propolis: Chrysin, Caffeic Acid, p-Coumaric Acid, and Ferulic Acid Induce PRODH/POX-Dependent Apoptosis in Human Tongue Squamous Cell Carcinoma Cell (CAL-27).

    Science.gov (United States)

    Celińska-Janowicz, Katarzyna; Zaręba, Ilona; Lazarek, Urszula; Teul, Joanna; Tomczyk, Michał; Pałka, Jerzy; Miltyk, Wojciech

    2018-01-01

    Propolis evokes several therapeutic properties, including anticancer activity. These activities are attributed to the action of polyphenols. Previously it has been demonstrated, that one of the most abundant polyphenolic compounds in ethanolic extracts of propolis are chrysin, caffeic acid, p -coumaric acid, and ferulic acid. Although their pro-apoptotic activity on human tongue squamous cell carcinoma cells (CAL-27) was established previously, the detailed mechanism of this process remains unclear. Considering the crucial role of proline metabolism and proline dehydrogenase/proline oxidase (PRODH/POX) in the regulation of cancer cell survival/apoptosis, we studied these processes in polyphenol-treated CAL-27 cells. All studied polyphenols evoked anti-proliferative activity, accompanied by increased PRODH/POX, P53, active caspases-3 and -9 expressions and decreased collagen biosynthesis, prolidase activity and proline concentration in CAL-27 cells. These data suggest that polyphenols of propolis induce PRODH/POX-dependent apoptosis through up-regulation of mitochondrial proline degradation and down-regulation of proline utilization for collagen biosynthesis.

  3. Additions of caffeic acid, ascorbyl palmitate or gamma-tocopherol to fish oil-enriched energy bars affect lipid oxidation differently

    DEFF Research Database (Denmark)

    Horn, Anna Frisenfeldt; Nielsen, Nina Skall; Jacobsen, Charlotte

    2009-01-01

    The objectives of the study were to investigate the effects of caffeic acid, ascorbyl palmitate and gamma-tocopherol on protection of fish oil-enriched energy bars against lipid oxidation during storage for 10 weeks at room temperature. The lipophilic gamma-tocopherol reduced lipid oxidation during...... storage when added at a concentration above 440 mu g/g fish oil. However, the best antioxidative effect was observed when it was added at a concentration of 660 mu g/g fish oil. In contrast, prooxidative effects were observed when using either gamma-tocopherol at concentrations below 220 mu g/g fish oil......, or the hydrophilic caffeic acid, or the amphiphilic ascorbyl palmitate at concentrations of 75, 150 and 300 mu g/g fish oil. Prooxidative effects were observed as an increase in the formation of lipid hydroperoxides and volatile secondary oxidation products, as well as the development of rancid off...

  4. Caffeic acid, morin hydrate and quercetin partially attenuate sulfur mustard-induced cell death by inhibiting the lipoxygenase pathway.

    Science.gov (United States)

    Kim, Shin; Jeong, Kwang-Joon; Cho, Sung Kweon; Park, Joo-Won; Park, Woo-Jae

    2016-11-01

    Sulfur mustard (SM) is an alkylating agent, which has been used as in chemical warfare in a number of conflicts. As the generation of reactive oxygen species (ROS), and adducts in DNA and proteins have been suggested as the mechanism underlying SM‑induced cytotoxicity, the present study screened several antioxidant candidates, including tannic acid, deferoxamine mesylate, trolox, vitamin C, ellagic acid and caffeic acid (CA) to assess their potential as therapeutic agents for SM‑induced cell death. Among several antioxidants, CA partially alleviated SM‑induced cell death in a dose‑dependent manner. Although CA treatment decreased the phosphorylation of p38 mitogen‑activated protein (MAP) kinase and p53, p38 MAP kinase inhibition by SB203580 did not affect SM‑induced cell death. As CA has also been reported as a 15‑lipoxygenase (15‑LOX) inhibitor, the role of 15‑LOX in SM‑induced cytotoxicity was also examined. Similar to the results observed with CA, treatment with PD146176, a specific 15‑LOX inhibitor, decreased SM‑induced cytotoxicity, accompanied by decreases in the production of tumor necrosis factor‑α and 15‑hydroxyeicosatetraenoic acid. Furthermore, the present study investigated the protective effects of two natural 15‑LOX inhibitors, morin hydrate and quercetin, in SM‑induced cytotoxicity. As expected, these inhibitors had similar protective effects against SM‑induced cytotoxicity. These antioxidants also reduced the generation of ROS and nitrate/nitrite. Therefore, the results of the present study indicated that the natural products, CA, quercetin and morin hydrate, offer potential as adjuvant therapeutic agents for SM‑induced toxicity, not only by reducing inflammation mediated by the p38 and LOX signaling pathways, but also by decreasing the generation of ROS and nitrate/nitrite.

  5. Caffeic Acid Derivatives in Market Available Lamiaceae and Echinacea purpurea Products

    Science.gov (United States)

    Fresh basil leaves contain chicoric acid, the principal phenolic compound of Echinacea purpurea and purportedly the active ingredient in its dietary supplements. Our group discovered and first reported chicoric acid in basil. This following study examined the distribution of chicoric acid within the...

  6. Poly(3-hydroxybutyrate)/caffeic acid electrospun fibrous materials coated with polyelectrolyte complex and their antibacterial activity and in vitro antitumor effect against HeLa cells

    Energy Technology Data Exchange (ETDEWEB)

    Ignatova, Milena G. [Laboratory of Bioactive Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev St, Bl. 103A, BG-1113 Sofia (Bulgaria); Manolova, Nevena E., E-mail: manolova@polymer.bas.bg [Laboratory of Bioactive Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev St, Bl. 103A, BG-1113 Sofia (Bulgaria); Rashkov, Iliya B. [Laboratory of Bioactive Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev St, Bl. 103A, BG-1113 Sofia (Bulgaria); Markova, Nadya D. [Institute of Microbiology, Bulgarian Academy of Sciences, Acad. G. Bonchev Bl. 26, BG-1113 Sofia (Bulgaria); Toshkova, Reneta A.; Georgieva, Ani K.; Nikolova, Elena B. [Institute of Experimental Morphology, Pathology and Anthropology with Museum, Bulgarian Academy of Sciences, Acad. G. Bonchev St, bl. 25, BG-1113 Sofia (Bulgaria)

    2016-08-01

    The purpose of this work was to investigate the possibility for the preparation of new poly(3-hydroxybutyrate) (PHB)/poly(ethylene glycol) (PEG)-based fibrous materials containing natural phenolic compound caffeic acid (CA) of diverse architectures, as well as to study the impact of the fiber composition on the in vitro CA release profile and on the biological properties of the fibrous materials. The application of the one-pot electrospinning enabled the fabrication of nanofibrous materials from PHB and PEG loaded with the CA. Materials with targeted design were obtained by coating with polyelectrolyte complex of alginate (Alg) and N,N,N-trimethylchitosan (TMCh). Three different processing paths were used to obtain coated mats: (i) with CA incorporated in the PHB/PEG core; (ii) with CA embedded in the Alg layer; and (iii) with CA included in the TMCh layer. The in vitro release of CA was modulated by controlling the composition and the architecture of the nanofibrous mats. The performed microbiological screening and MTT cell viability studies revealed that in contrast to the bare mats, the CA-containing nanofibrous materials were effective in suppressing the growth of the Gram-positive bacteria Staphylococcus aureus and the Gram-negative bacteria Escherichia coli and displayed good cytotoxicity against human cervical HeLa tumor cells. In addition, the proliferation of murine spleen lymphocytes and peritoneal macrophages was increased by the prepared CA-containing nanofibrous materials. The obtained materials are promising for antibacterial wound dressing applications as well as for application in local treatment of cervical tumors. - Highlights: • New caffeic acid-loaded materials from PHB and PEG were prepared by electrospinning. • Different design is achieved by coating and formation of polyelectrolyte complexes. • The control on the architecture of the mats enables modulating caffeic acid release. • The caffeic acid-loaded mats suppress the growth of

  7. Poly(3-hydroxybutyrate)/caffeic acid electrospun fibrous materials coated with polyelectrolyte complex and their antibacterial activity and in vitro antitumor effect against HeLa cells

    International Nuclear Information System (INIS)

    Ignatova, Milena G.; Manolova, Nevena E.; Rashkov, Iliya B.; Markova, Nadya D.; Toshkova, Reneta A.; Georgieva, Ani K.; Nikolova, Elena B.

    2016-01-01

    The purpose of this work was to investigate the possibility for the preparation of new poly(3-hydroxybutyrate) (PHB)/poly(ethylene glycol) (PEG)-based fibrous materials containing natural phenolic compound caffeic acid (CA) of diverse architectures, as well as to study the impact of the fiber composition on the in vitro CA release profile and on the biological properties of the fibrous materials. The application of the one-pot electrospinning enabled the fabrication of nanofibrous materials from PHB and PEG loaded with the CA. Materials with targeted design were obtained by coating with polyelectrolyte complex of alginate (Alg) and N,N,N-trimethylchitosan (TMCh). Three different processing paths were used to obtain coated mats: (i) with CA incorporated in the PHB/PEG core; (ii) with CA embedded in the Alg layer; and (iii) with CA included in the TMCh layer. The in vitro release of CA was modulated by controlling the composition and the architecture of the nanofibrous mats. The performed microbiological screening and MTT cell viability studies revealed that in contrast to the bare mats, the CA-containing nanofibrous materials were effective in suppressing the growth of the Gram-positive bacteria Staphylococcus aureus and the Gram-negative bacteria Escherichia coli and displayed good cytotoxicity against human cervical HeLa tumor cells. In addition, the proliferation of murine spleen lymphocytes and peritoneal macrophages was increased by the prepared CA-containing nanofibrous materials. The obtained materials are promising for antibacterial wound dressing applications as well as for application in local treatment of cervical tumors. - Highlights: • New caffeic acid-loaded materials from PHB and PEG were prepared by electrospinning. • Different design is achieved by coating and formation of polyelectrolyte complexes. • The control on the architecture of the mats enables modulating caffeic acid release. • The caffeic acid-loaded mats suppress the growth of

  8. Effect of Caffeic Acid Phenethyl Ester on Vascular Damage Caused by Consumption of High Fructose Corn Syrup in Rats.

    Science.gov (United States)

    Gun, Aburrahman; Ozer, Mehmet Kaya; Bilgic, Sedat; Kocaman, Nevin; Ozan, Gonca

    2016-01-01

    Fructose corn syrup is cheap sweetener and prolongs the shelf life of products, but fructose intake causes hyperinsulinemia, hypertriglyceridemia, and hypertension. All of them are referred to as metabolic syndrome and they are risk factors for cardiovascular diseases. Hence, the harmful effects of increased fructose intake on health and their prevention should take greater consideration. Caffeic Acid Phenethyl Ester (CAPE) has beneficial effects on metabolic syndrome and vascular function which is important in the prevention of cardiovascular disease. However, there are no known studies about the effect of CAPE on fructose-induced vascular dysfunction. In this study, we examined the effect of CAPE on vascular dysfunction due to high fructose corn syrup (HFCS). HFCS (6 weeks, 30% fed with drinking water) caused vascular dysfunction, but treatment with CAPE (50 micromol/kg i.p. for the last two weeks) effectively restored this problem. Additionally, hypertension in HFCS-fed rats was also decreased in CAPE supplemented rats. CAPE supplements lowered HFCS consumption-induced raise in blood glucose, homocysteine, and cholesterol levels. The aorta tissue endothelial nitric oxide synthase (eNOS) production was decreased in rats given HFCS and in contrast CAPE supplementation efficiently increased its production. The presented results showed that HFCS-induced cardiovascular abnormalities could be prevented by CAPE treatment.

  9. Effect of Caffeic Acid Phenethyl Ester on Vascular Damage Caused by Consumption of High Fructose Corn Syrup in Rats

    Directory of Open Access Journals (Sweden)

    Aburrahman Gun

    2016-01-01

    Full Text Available Fructose corn syrup is cheap sweetener and prolongs the shelf life of products, but fructose intake causes hyperinsulinemia, hypertriglyceridemia, and hypertension. All of them are referred to as metabolic syndrome and they are risk factors for cardiovascular diseases. Hence, the harmful effects of increased fructose intake on health and their prevention should take greater consideration. Caffeic Acid Phenethyl Ester (CAPE has beneficial effects on metabolic syndrome and vascular function which is important in the prevention of cardiovascular disease. However, there are no known studies about the effect of CAPE on fructose-induced vascular dysfunction. In this study, we examined the effect of CAPE on vascular dysfunction due to high fructose corn syrup (HFCS. HFCS (6 weeks, 30% fed with drinking water caused vascular dysfunction, but treatment with CAPE (50 micromol/kg i.p. for the last two weeks effectively restored this problem. Additionally, hypertension in HFCS-fed rats was also decreased in CAPE supplemented rats. CAPE supplements lowered HFCS consumption-induced raise in blood glucose, homocysteine, and cholesterol levels. The aorta tissue endothelial nitric oxide synthase (eNOS production was decreased in rats given HFCS and in contrast CAPE supplementation efficiently increased its production. The presented results showed that HFCS-induced cardiovascular abnormalities could be prevented by CAPE treatment.

  10. CO₂ enrichment can produce high red leaf lettuce yield while increasing most flavonoid glycoside and some caffeic acid derivative concentrations.

    Science.gov (United States)

    Becker, Christine; Kläring, Hans-Peter

    2016-05-15

    Carbon dioxide (CO2) enrichment is a common practice in greenhouses to increase crop yields up to 30%. Yet, reports on the effect on foliar phenolic compounds vary. We studied the effect on two red leaf lettuce cultivars, grown for 25 days in growth chambers at CO2 concentrations of 200 or 1,000 ppm, with some plants exchanged between treatments after 11 days. As expected, head mass increased with higher CO2 concentration. Regression analysis, corrected for head mass, showed increased concentrations of most flavonoid glycosides at high CO2 concentrations while only some caffeic acid derivatives were increased, and not uniformly in both cultivars. Sugar concentrations increased with CO2 concentration. Generally, conditions in the 10 days before harvest determined concentrations. We suspect that phenolic compounds were mainly accumulated because plenty of precursors were available. The results indicate that CO2 enrichment can result in high yields of red leaf lettuce rich in phenolic compounds. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  11. Nanomolar electrochemical detection of caffeic acid in fortified wine samples based on gold/palladium nanoparticles decorated graphene flakes.

    Science.gov (United States)

    Thangavelu, Kokulnathan; Raja, Nehru; Chen, Shen-Ming; Liao, Wei-Cheng

    2017-09-01

    Amalgamation of noble metal nanomaterials on graphene flakes potentially paves one way to improve their physicochemical properties. This paper deals with the simultaneous electrochemical deposition of gold and palladium nanoparticles on graphene flakes (Au/PdNPs-GRF) for the sensitive determination of caffeic acid (CA). The physiochemical properties of the prepared Au/PdNPs-GRF was characterized by using numerous analytical techniques such as scanning electron microscopy, electron dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction, Raman spectroscopy and electrochemical impedance spectroscopy. The enhanced electrochemical determination of CA at Au/PdNPs deposition on GRF were studied by using cyclic voltammetry and differential pulse voltammetry. In results, Au/PdNPs-GRF electrode exhibited an excellent electrocatalytic activity towards CA with wide linear range and low limit of detection of 0.03-938.97µM and 6nM, respectively. Eventually, the Au/PdNPs-GRF was found as a selective and stable active material for the sensing of CA. In addition, the proposed sensor showed the adequate results in real sample analysis. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Fibrinolytic Activity and Dose-Dependent Effect of Incubating Human Blood Clots in Caffeic Acid Phenethyl Ester: In Vitro Assays

    Directory of Open Access Journals (Sweden)

    Abuzar Elnager

    2015-01-01

    Full Text Available Background. Caffeic acid phenethyl ester (CAPE has been reported to possess time-dependent fibrinolytic activity by in vitro assay. This study is aimed at investigating fibrinolytic dose-dependent activity of CAPE using in vitro assays. Methods. Standardized human whole blood (WB clots were incubated in either blank controls or different concentrations of CAPE (3.75, 7.50, 15.00, 22.50, and 30.00 mM. After 3 hours, D-dimer (DD levels and WB clot weights were measured for each concentration. Thromboelastography (TEG parameters were recorded following CAPE incubation, and fibrin morphology was examined under a confocal microscope. Results. Overall, mean DD (μg/mL levels were significantly different across samples incubated with different CAPE concentrations, and the median pre- and postincubation WB clot weights (grams were significantly decreased for each CAPE concentration. Fibrin removal was observed microscopically and indicated dose-dependent effects. Based on the TEG test, the Ly30 fibrinolytic parameter was significantly different between samples incubated with two different CAPE concentrations (15.0 and 22.50 mM. The 50% effective dose (ED50 of CAPE (based on DD was 1.99 mg/mL. Conclusions. This study suggests that CAPE possesses fibrinolytic activity following in vitro incubation and that it has dose-dependent activities. Therefore, further investigation into CAPE as a potential alternative thrombolytic agent should be conducted.

  13. Protective role of caffeic acid on lambda cyhalothrin-induced changes in sperm characteristics and testicular oxidative damage in rats.

    Science.gov (United States)

    Abdallah, Fatma Ben; Fetoui, Hamadi; Zribi, Nassira; Fakhfakh, Feiza; Keskes, Leila

    2012-08-01

    The synthetic pyrethroids are expected to cause deleterious effects on most of the organs and especially on the male reproductive system. The current study was performed to assess the adverse effect of lambda cyhalothrin (LC) on reproductive organs and fertility in male rats and to evaluate the protective role of caffeic acid phenethyl ester (CAPE) in alleviating the detrimental effect of LC on male fertility. A total of 48 male rats were divided into 4 groups (12 rats each): control group received distilled water ad libitum and 1 ml of vehicle solution given intraperitoneally (i.p.); CAPE-treated group received a single i.p. dose of CAPE (10 μmol kg⁻¹ day⁻¹); LC-treated group received 668 ppm of LC through drinking water; and CAPE + LC-treated group received an i.p. injection of CAPE (10 μmol kg⁻¹ day⁻¹) 12 h before the LC administration. The experiment was conducted for 10 consecutive weeks. LC caused a significant increase in testicular malondialdehyde, catalase, superoxide dismutase, glutathione-S-transferase activities, and sperm abnormalities and a significant reduction in testicular glutathione concentration, sperm count, sperm motility, and a live sperm percentage. Conversely, treatment with CAPE improved the reduction in the sperm characteristics, LC-induced oxidative damage of testes and the testicular histopathological alterations. Results indicate that LC exerts significant harmful effects on the male reproductive system and that CAPE reduced the deleterious effects of LC on male fertility.

  14. Novel Antidepressant-Like Activity of Caffeic Acid Phenethyl Ester Is Mediated by Enhanced Glucocorticoid Receptor Function in the Hippocampus

    Directory of Open Access Journals (Sweden)

    Mi-Sook Lee

    2014-01-01

    Full Text Available Caffeic acid phenethyl ester (CAPE is an active component of propolis that has a variety of potential pharmacological effects. Although we previously demonstrated that propolis has antidepressant-like activity, the effect of CAPE on this activity remains unknown. The present study assessed whether treatment with CAPE (5, 10, and 20 µmol/kg for 21 days has an antidepressant-like effect in mice subjected to chronic unpredictable stress via tail suspension (TST and forced swim (FST tests. CAPE administration induced behaviors consistent with an antidepressant effect, evidenced by decreased immobility in the TST and FST independent of any effect on serum corticosterone secretion. Western blots, conducted subsequent to behavioral assessment, revealed that CAPE significantly decreased glucocorticoid receptor phosphorylation at S234 (pGR(S234, resulting in an increased pGR(S220/S234 ratio. We also observed negative correlations between pGR(S220/(S234 and p38 mitogen-activated protein kinase (p38MAPK phosphorylation, which was decreased by CAPE treatment. These findings suggest that CAPE treatment exerts an antidepressant-like effect via downregulation of p38MAPK phosphorylation, thereby contributing to enhanced GR function.

  15. Synergistic Antibacterial Effects of Chitosan-Caffeic Acid Conjugate against Antibiotic-Resistant Acne-Related Bacteria.

    Science.gov (United States)

    Kim, Ji-Hoon; Yu, Daeung; Eom, Sung-Hwan; Kim, Song-Hee; Oh, Junghwan; Jung, Won-Kyo; Kim, Young-Mog

    2017-06-08

    The object of this study was to discover an alternative therapeutic agent with fewer side effects against acne vulgaris, one of the most common skin diseases. Acne vulgaris is often associated with acne-related bacteria such as Propionibacterium acnes , Staphylococcus epidermidis , Staphylococcus aureus , and Pseudomonas aeruginosa . Some of these bacteria exhibit a resistance against commercial antibiotics that have been used in the treatment of acne vulgaris (tetracycline, erythromycin, and lincomycin). In the current study, we tested in vitro antibacterial effect of chitosan-phytochemical conjugates on acne-related bacteria. Three chitosan-phytochemical conjugates used in this study exhibited stronger antibacterial activity than that of chitosan (unmodified control). Chitosan-caffeic acid conjugate (CCA) showed the highest antibacterial effect on acne-related bacteria along with minimum inhibitory concentration (MIC; 8 to 256 μg/mL). Additionally, the MIC values of antibiotics against antibiotic-resistant P. acnes and P. aeruginosa strains were dramatically reduced in combination with CCA, suggesting that CCA would restore the antibacterial activity of the antibiotics. The analysis of fractional inhibitory concentration (FIC) indices clearly revealed a synergistic antibacterial effect of CCA with antibiotics. Thus, the median sum of FIC (∑FIC) values against the antibiotic-resistant bacterial strains ranged from 0.375 to 0.533 in the combination mode of CCA and antibiotics. The results of the present study suggested a potential possibility of chitosan-phytochemical conjugates in the control of infections related to acne vulgaris.

  16. Crystallization and preliminary X-ray diffraction analysis of a Lys49-phospholipase A2 complexed with caffeic acid, a molecule with inhibitory properties against snake venoms

    International Nuclear Information System (INIS)

    Shimabuku, Patrícia S.; Fernandes, Carlos A. H.; Magro, Angelo J.; Costa, Tássia R.; Soares, Andreimar M.; Fontes, Marcos R. M.

    2011-01-01

    Piratoxin I, a noncatalytic and myotoxic Lys49-phospholipase A 2 from B. pirajai venom, was cocrystallized with the inhibitor caffeic acid and a data set was collected to a resolution of 1.65 Å. The electron-density map unambiguously indicated that three inhibitor molecules interact with the C-terminus of the protein. Phospholipases A 2 (PLA 2 s) are one of the main components of bothropic venoms; in addition to their phospholipid hydrolysis action, they are involved in a wide spectrum of pharmacological activities, including neurotoxicity, myotoxicity and cardiotoxicity. Caffeic acid is an inhibitor that is present in several plants and is employed for the treatment of ophidian envenomations in the folk medicine of many developing countries; as bothropic snake bites are not efficiently neutralized by conventional serum therapy, it may be useful as an antivenom. In this work, the cocrystallization and preliminary X-ray diffraction analysis of the Lys49-PLA 2 piratoxin I from Bothrops pirajai venom in the presence of the inhibitor caffeic acid (CA) are reported. The crystals diffracted X-rays to 1.65 Å resolution and the structure was solved by molecular-replacement techniques. The electron-density map unambiguously indicated the presence of three CA molecules that interact with the C-terminus of the protein. This is the first time a ligand has been observed bound to this region and is in agreement with various experiments previously reported in the literature

  17. An approach for degradation of grape seed and skin proanthocyanidin polymers into oligomers by sulphurous acid.

    Science.gov (United States)

    Luo, Lanxin; Cui, Yan; Cheng, Jinhui; Fang, Bairui; Wei, Zongmin; Sun, Baoshan

    2018-08-01

    To develop an efficient method for degradation of grape seed and skin proanthocyanidins polymers into oligomers, an optimized sulphurous acid degradation conditions for grape seed with the temperature of 60 °C, reaction time of 60 min and sample-sulphurous acid ratio of 1:0.2, and for grape skin with the temperature of 40 °C, reaction time of 60 min and sample-sulphurous acid ratio of 1:0.2, were established. Afterwards, HSCCC and prep-HPLC were used to fractionate and isolate individual proanthocyanidin oligomers from the degradation products. Total of ten dimeric or trimeric procyanidins were obtained, and most of them presented high yield (from 0.7 mg to 13.6 mg per run in grape seed and from 0.5 mg to 4.1 mg per run in grape skin) and high purity (over 90%). The proposed method provides a new way for large preparation of oligomeric proanthocyanidins from naturally abundant and wasted polymeric ones. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Caffeic acid phenethyl ester preferentially sensitizes CT26 colorectal adenocarcinoma to ionizing radiation without affecting bone marrow radioresponse

    International Nuclear Information System (INIS)

    Chen, Y.-J.; Liao, H.-F.; Tsai, T.-H.; Wang, S.-Y.; Shiao, M.-S.

    2005-01-01

    Purpose: Caffeic acid phenethyl ester (CAPE), a component of propolis, was reported capable of depleting glutathione (GSH). We subsequently examined the radiosensitizing effect of CAPE and its toxicity. Methods and Materials: The effects of CAPE on GSH level, GSH metabolism enzyme activities, NF-κB activity, and radiosensitivity in mouse CT26 colorectal adenocarcinoma cells were determined. BALB/c mouse with CT26 cells implantation was used as a syngeneic in vivo model for evaluation of treatment and toxicity end points. Results: CAPE entered CT26 cells rapidly and depleted intracellular GSH in CT26 cells, but not in bone marrow cells. Pretreatment with nontoxic doses of CAPE significantly enhanced cell killing by ionizing radiation (IR) with sensitizer enhancement ratios up to 2.2. Pretreatment of CT26 cells with N-acetyl-L-cysteine reversed the GSH depletion activity and partially blocked the radiosensitizing effect of CAPE. CAPE treatment in CT26 cells increased glutathione peroxidase, decreased glutathione reductase, and did not affect glutathione S-transferase or γ-glutamyl transpeptidase activity. Radiation activated NF-κB was reversed by CAPE pretreatment. In vivo study revealed that pretreatment with CAPE before IR resulted in greater inhibition of tumor growth and prolongation of survival in comparison with IR alone. Pretreatment with CAPE neither affected body weights nor produced hepatic, renal, or hematopoietic toxicity. Conclusions: CAPE sensitizes CT26 colorectal adenocarcinoma to IR, which may be via depleting GSH and inhibiting NF-κB activity, without toxicity to bone marrow, liver, and kidney

  19. Direct interaction between caffeic acid phenethyl ester and human neutrophil elastase inhibits the growth and migration of PANC-1 cells.

    Science.gov (United States)

    Duan, Jianhui; Xiaokaiti, Yilixiati; Fan, Shengjun; Pan, Yan; Li, Xin; Li, Xuejun

    2017-05-01

    Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignant tumors of the digestive system, but the mechanisms of its development and progression are unclear. Inflammation is thought to be fundamental to pancreatic cancer development and caffeic acid phenethyl ester (CAPE) is an active component of honey bee resin or propolis with anti-inflammatory and anticancer activities. We investigated the inhibitory effects of CAPE on cell growth and migration induced by human neutrophil elastase (HNE) and report that HNE induced cancer cell migration at low doses and growth at higher doses. In contrast, lower CAPE doses inhibited migration and higher doses of CAPE inhibited the growth induced by HNE. HNE activity was significantly inhibited by CAPE (7.5-120 µM). Using quantitative real-time PCR and western blotting, we observed that CAPE (18-60 µM) did not affect transcription and translation of α1-antitrypsin (α1-AT), an endogenous HNE inhibitor. However, in an in silico drug target docking model, we found that CAPE directly bound to the binding pocket of HNE (25.66 kcal/mol) according to CDOCKER, and the residue of the catalytic site stabilized the interaction between CAPE and HNE as evidenced by molecular dynamic simulation. Response unit (RU) values of surface plasmon resonance (SPR) significantly increased with incremental CAPE doses (7.5-120 µM), indicating that CAPE could directly bind to HNE in a concentration-dependent manner. Thus, CAPE is an effective inhibitor of HNE via direct interaction whereby it inhibits the migration and growth of PANC-1 cells in a dose-dependent manner.

  20. Kinetic properties of two Rhizopus exo-polygalacturonase enzymes hydrolyzing galacturonic acid oligomers using isothermal titration calorimetry

    Science.gov (United States)

    The kinetic characteristics of two Rhizopus oryzae exo-polygalacturonases acting on galacturonic acid oligomers (GalpA) were determined using isothermal titration calorimetry (ITC). RPG15 hydrolyzing (GalpA)2 demonstrated a Km of 55 uM and kcat of 10.3 s^-1^ while RPG16 was shown to have greater af...

  1. Acid detergent lignin, lodging resistance index, and expression of the caffeic acid O-methyltransferase gene in brown midrib-12 sudangrass.

    Science.gov (United States)

    Li, Yuan; Liu, Guibo; Li, Jun; You, Yongliang; Zhao, Haiming; Liang, Huan; Mao, Peisheng

    2015-09-01

    Understanding the relationship between acid detergent lignin (ADL) and lodging resistance index (LRI) is essential for breeding new varieties of brown midrib (bmr) sudangrass (Sorghum sudanense (Piper) Stapf.). In this study, bmr-12 near isogenic lines and their wild-types obtained by back cross breeding were used to compare relevant forage yield and quality traits, and to analyze expression of the caffeic acid O-methyltransferase (COMT) gene using quantitative real time-PCR. The research showed that the mean ADL content of bmr-12 mutants (20.94 g kg(-1)) was significantly (P bmr-12 mutants (0.29) was significantly (P bmr-12 materials (r = -0.44, P > 0.05). Sequence comparison of the COMT gene revealed two point mutations present in bmr-12 but not in the wild-type, the second mutation changed amino acid 129 of the protein from Gln (CAG) to a stop codon (UAG). The relative expression level of COMT gene was significantly reduced, which likely led to the decreased ADL content observed in the bmr-12 mutant.

  2. Synthesis of caffeic acid molecularly imprinted polymer microspheres and high-performance liquid chromatography evaluation of their sorption properties.

    Science.gov (United States)

    Valero-Navarro, Angel; Gómez-Romero, María; Fernández-Sánchez, Jorge F; Cormack, Peter A G; Segura-Carretero, Antonio; Fernández-Gutiérrez, Alberto

    2011-10-14

    In the current work, a molecularly imprinted polymer (MIP) has been synthesised and used to enable the extraction of a naturally-occurring antioxidant from complex media. More specifically, we describe the first example of a caffeic acid (CA) MIP which has been synthesised in the form of well-defined polymer microspheres, and its use for the extraction of CA from fruit juice sample. The CA MIP was synthesised by precipitation polymerisation using 4-vinylpyridine as functional monomer, divinylbenzene-80 as crosslinker and acetonitrile:toluene (75/25, v/v) as porogen. The particle sizing and morphological characterisation of the polymers was carried out by means of scanning electron microscopy (narrow particle size distribution; ∼5 and 1.5 μm particle diameters for the MIP and NIP [non-imprinted polymer], respectively) and nitrogen sorption porosimetry (specific surface areas of 340 and 350 m(2)g(-1), and specific pore volumes of 0.17 and 0.19 cm(3)g(-1) for the MIP and NIP, respectively). The polymers were evaluated further by batch rebinding experiments, and from the derived isotherms their binding capacity and binding strength were determined (number of binding sites (N(K))=0.6 and 0.3 mmol g(-1) for the MIP and NIP, respectively, and apparent average adsorption constant (K(N))=10.0 and 1.6L mmol(-1) for the MIP and NIP, respectively). To evaluate the molecular recognition character of the MIP it was packed into a stainless steel column (50 mm × 4.6 mm i.d.) and evaluated as an HPLC-stationary phase. The mobile phase composition, flow rate, and the elution profile were then optimised in order to improve the peak shape without negatively affecting the imprinting factor (IF). Very interesting, promising properties were revealed. The imprinting factor (IF) under the optimised conditions was 11.9. Finally, when the imprinted LC column was used for the selective recognition of CA over eight related compounds, very good selectivity was obtained. This outcome enabled

  3. Caffeic acid phenethyl ester suppresses melanoma tumor growth by inhibiting PI3K/AKT/XIAP pathway.

    Science.gov (United States)

    Pramanik, Kartick C; Kudugunti, Shashi K; Fofaria, Neel M; Moridani, Majid Y; Srivastava, Sanjay K

    2013-09-01

    Melanoma is highly metastatic and resistant to chemotherapeutic drugs. Our previous studies have demonstrated that caffeic acid phenethyl ester (CAPE) suppresses the growth of melanoma cells and induces reactive oxygen species generation. However, the exact mechanism of the growth suppressive effects of CAPE was not clear. Here, we determined the potential mechanism of CAPE against melanoma in vivo and in vitro. Administration of 10 mg/kg/day CAPE substantially suppressed the growth of B16F0 tumor xenografts in C57BL/6 mice. Tumors from CAPE-treated mice showed reduced phosphorylation of phosphoinositide 3-kinase, AKT, mammalian target of rapamycin and protein level of X-linked inhibitor of apoptosis protein (XIAP) and enhanced the cleavage of caspase-3 and poly (ADP ribose) polymerase. In order to confirm the in vivo observations, melanoma cells were treated with CAPE. CAPE treatment suppressed the activating phosphorylation of phosphoinositide 3-kinase at Tyr 458, phosphoinositide-dependent kinase-1 at Ser 241, mammalian target of rapamycin at Ser 2448 and AKT at Ser 473 in B16F0 and SK-MEL-28 cells in a concentration and time-dependent study. Furthermore, the expression of XIAP, survivin and BCL-2 was downregulated by CAPE treatment in both cell lines. Significant apoptosis was observed by CAPE treatment as indicated by cleavage of caspase-3 and poly (ADP ribose) polymerase. AKT kinase activity was inhibited by CAPE in a concentration-dependent manner. CAPE treatment increased the nuclear translocation of XIAP, indicating increased apoptosis in melanoma cells. To confirm the involvement of reactive oxygen species in the inhibition of AKT/XIAP pathway, cells were treated with antioxidant N-acetyl-cysteine (NAC) prior to CAPE treatment. Our results indicate that NAC blocked CAPE-mediated AKT/XIAP inhibition and protected the cells from apoptosis. Because AKT regulates XIAP, their interaction was examined by immunoprecipitation studies. Our results show that CAPE

  4. Effect of caffeic acid phenethyl ester on Prevotella intermedia lipopolysaccharide-induced production of proinflammatory mediators in murine macrophages.

    Science.gov (United States)

    Choi, E-Y; Choe, S-H; Hyeon, J-Y; Choi, J-I; Choi, I S; Kim, S-J

    2015-12-01

    Caffeic acid phenethyl ester (CAPE) has numerous potentially beneficial properties, including antioxidant, immunomodulatory and anti-inflammatory activities. However, the effect of CAPE on periodontal disease has not been studied before. This study was designed to investigate the efficacy of CAPE in ameliorating the production of proinflammatory mediators in macrophages activated by lipopolysaccharide (LPS) from Prevotella intermedia, a pathogen implicated in periodontal disease. LPS from P. intermedia ATCC 25611 was isolated by using the standard hot phenol-water method. Culture supernatants were assayed for nitric oxide (NO), interleukin (IL)-1β and IL-6. We used real-time polymerase chain reaction to quantify inducible NO synthase, IL-1β, IL-6, heme oxygenase (HO)-1 and suppressors of cytokine signaling (SOCS) 1 mRNA expression. HO-1 protein expression and levels of signaling proteins were assessed by immunoblot analysis. DNA-binding activities of NF-κB subunits were analyzed by using the enzyme-linked immunosorbent assay-based kits. CAPE exerted significant inhibitory effects on P. intermedia LPS-induced production of NO, IL-1β and IL-6 as well as their mRNA expression in RAW264.7 cells. CAPE-induced HO-1 expression in cells activated with P. intermedia LPS, and selective inhibition of HO-1 activity by tin protoporphyrin IX attenuated the inhibitory effect of CAPE on LPS-induced NO production. CAPE did not interfere with IκB-α degradation induced by P. intermedia LPS. Instead, CAPE decreased nuclear translocation of NF-κB p65 and p50 subunits induced with LPS, and lessened LPS-induced p50 binding activity. Further, CAPE showed strong inhibitory effects on LPS-induced signal transducer and activator of transcription 1 and 3 phosphorylation. Besides, CAPE significantly elevated SOCS1 mRNA expression in P. intermedia LPS-stimulated cells. Modulation of host response by CAPE may represent an attractive strategy towards the treatment of periodontal disease

  5. Experimental and theoretical investigation of interaction between bovine serum albumin and the mixture of caffeic acid and salicylic acid as the antioxidants

    International Nuclear Information System (INIS)

    Benvidi, Ali; Rezaeinasab, Masoud; Gharaghani, Sajjad; Abbasi, Saleheh; Zare, Hamid R.

    2017-01-01

    In the present work, interaction between bovine serum albumin (BSA) with caffeic acid (CA), salicylic acid (SA) and the mixture of these components were studied by experimental and computational methods In the experimental measurements, differential pulse voltammetry (DPV) and UV–vis spectrophotometry (UV–Vis) were separately used to investigate the nature of interactions. Also, some of the thermodynamics parameters were obtained from these measurements. At the second step, the chemometric methods including multivariate curve resolution–alternating least squares (MCR–ALS) and parallel factor analysis (PARAFAC) were used since the results of the experimental measurements have a strongly overlapping signals. For this purpose, a three-way array was resolved by PARAFAC and a row- and column-wise augmented matrix, which built with DPV and UV–vis sub-matrices, were analyzed using MCR-ALS. The interesting results for stoichiometry and electrochemical behaviors of these components were obtained by using the proposed algorithms. Finally, molecular docking were applied to compare experimentally determined binding parameters with molecular modelling. According to the obtained results an excellent agreement was found between experimental and computational results.

  6. Reaction Mechanisms and Structural and Physicochemical Properties of Caffeic Acid Grafted Chitosan Synthesized in Ascorbic Acid and Hydroxyl Peroxide Redox System.

    Science.gov (United States)

    Liu, Jun; Pu, Huimin; Chen, Chong; Liu, Yunpeng; Bai, Ruyu; Kan, Juan; Jin, Changhai

    2018-01-10

    The ascorbic acid (AA) and hydroxyl peroxide (H 2 O 2 ) redox pair induced free radical grafting reaction is a promising approach to conjugate phenolic groups with chitosan (CS). In order to reveal the exact mechanisms of the AA/H 2 O 2 redox pair induced grafting reaction, free radicals generated in the AA/H 2 O 2 redox system were compared with hydroxyl radical ( • OH) produced in the Fe 2+ /H 2 O 2 redox system. Moreover, the structural and physicochemical properties of caffeic acid grafted CS (CA-g-CS) synthesized in these two redox systems were compared. Results showed that only ascorbate radical (Asc •- ) was produced in the AA/H 2 O 2 system. The reaction between Asc •- and CS produced novel carbon-centered radicals, whereas no new free radicals were detected when • OH reacted with CS. Thin layer chromatography, UV-vis, Fourier transform infrared, and nuclear magnetic resonance spectroscopic analyses all confirmed that CA was successfully grafted onto CS through Asc •- . However, CA could be hardly grafted onto CS via • OH. CA-g-CS synthesized through Asc •- exhibited lower thermal stability and crystallinity than the reaction product obtained through • OH. For the first time, our results demonstrated that the synthesis of CA-g-CS in the AA/H 2 O 2 redox system was mediated by Asc •- rather than • OH.

  7. Cells Deficient in the Fanconi Anemia Protein FANCD2 are Hypersensitive to the Cytotoxicity and DNA Damage Induced by Coffee and Caffeic Acid.

    Science.gov (United States)

    Burgos-Morón, Estefanía; Calderón-Montaño, José Manuel; Orta, Manuel Luis; Guillén-Mancina, Emilio; Mateos, Santiago; López-Lázaro, Miguel

    2016-07-08

    Epidemiological studies have found a positive association between coffee consumption and a lower risk of cardiovascular disorders, some cancers, diabetes, Parkinson and Alzheimer disease. Coffee consumption, however, has also been linked to an increased risk of developing some types of cancer, including bladder cancer in adults and leukemia in children of mothers who drink coffee during pregnancy. Since cancer is driven by the accumulation of DNA alterations, the ability of the coffee constituent caffeic acid to induce DNA damage in cells may play a role in the carcinogenic potential of this beverage. This carcinogenic potential may be exacerbated in cells with DNA repair defects. People with the genetic disease Fanconi Anemia have DNA repair deficiencies and are predisposed to several cancers, particularly acute myeloid leukemia. Defects in the DNA repair protein Fanconi Anemia D2 (FANCD2) also play an important role in the development of a variety of cancers (e.g., bladder cancer) in people without this genetic disease. This communication shows that cells deficient in FANCD2 are hypersensitive to the cytotoxicity (clonogenic assay) and DNA damage (γ-H2AX and 53BP1 focus assay) induced by caffeic acid and by a commercial lyophilized coffee extract. These data suggest that people with Fanconi Anemia, or healthy people who develop sporadic mutations in FANCD2, may be hypersensitive to the carcinogenic activity of coffee.

  8. Caffeic acid, a coffee-related organic acid, inhibits infection by severe fever with thrombocytopenia syndrome virus in vitro.

    Science.gov (United States)

    Ogawa, Motohiko; Shirasago, Yoshitaka; Ando, Shuji; Shimojima, Masayuki; Saijo, Masayuki; Fukasawa, Masayoshi

    2018-04-05

    Severe fever with thrombocytopenia syndrome (SFTS) virus (SFTSV) causes tick-borne hemorrhagic fever in East Asia. The disease is characterized by high morbidity and mortality. Here, we evaluated the effects of caffeic acid (CA), a coffee-related organic acid with antiviral effects, against SFTSV infection. CA dose-dependently inhibited SFTSV infection in permissive human hepatoma Huh7.5.1-8 cells when SFTSV was added into the culture medium with CA. However, quinic acid (QA), another coffee-related organic acid, did not inhibit SFTSV infection. The 50% inhibitory concentration (IC 50 ) of CA against SFTSV was 0.048 mM, whereas its 50% cytotoxic concentration was 7.6 mM. The selectivity index (SI) was 158. Pre-incubation of SFTSV with CA for 4 h resulted in a greater inhibition of SFTSV infection (IC 50  = 0.019 mM; SI = 400). The pre-incubation substantially decreased viral attachment to the cells. CA treatment of the SFTSV-infected cells also inhibited the infection, albeit less effectively. CA activity after cell infection with SFTSV was more pronounced at a low multiplicity of infection (MOI) of 0.01 per cell (IC 50  = 0.18 mM) than at a high MOI of 1 per cell (IC 50  > 1 mM). Thus, CA inhibited virus spread by acting directly on the virus rather than on the infected cells. In conclusion, CA acted on SFTSV and inhibited viral infection and spread, mainly by inhibiting the binding of SFTSV to the cells. We therefore demonstrated CA to be a potential anti-SFTSV drug for preventing and treating SFTS. Copyright © 2018 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  9. Caffeic acid phenethyl ester protects against glucocorticoid-induced osteoporosis in vivo: Impact on oxidative stress and RANKL/OPG signals

    International Nuclear Information System (INIS)

    Tolba, Mai F.; El-Serafi, Ahmed T.; Omar, Hany A.

    2017-01-01

    Glucocorticoid-induced osteoporosis (GIO) is one of the most common causes of secondary osteoporosis. Given that glucocorticoids are considered as a main component of the treatment protocols for a variety of inflammation and immune-mediated diseases besides its use as adjuvant to several chemotherapeutic agents, it is crucial to find ways to overcome this critical adverse effect. Caffeic acid phenethyl ester (CAPE), which is a natural compound derived from honeybee propolis displayed promising antiosteoporotic effects against mechanical bone injury in various studies. The current work aimed at investigating the potential protective effect of CAPE against GIO in vivo with emphasis on the modulation of oxidative status and receptor activator of NF-kB ligand (RANKL)/osteoprotegrin (OPG) signaling. The results showed that CAPE opposed dexamethasone (DEX)-mediated alterations in bone histology and tartarate-resistant acid phosphatase (TRAP) activity. In addition, CAPE restored oxidative balance, Runt-related transcription factor 2 (RunX2) expression and reduced caspase-3 activity in femur tissues. Co-administration of CAPE with DEX normalized RANKL/OPG ratio and Akt activation indicating a reduction in DEX-osteoclastogenesis. In conclusion, concurrent treatment of CAPE with DEX exhibited promising effects in the protection against DEX-induced osteoporosis through opposing osteoclastogenesis and protecting osteoblasts. The potent antioxidant activity of CAPE is, at least in part, involved in its anti-apoptotic effects and modulation of RunX2 and RANKL/OPG signals. The use of CAPE-enriched propolis formulas is strongly recommended for patients on chronic glucocorticoid therapy to help in the attenuation of GIO. - Highlights: • Caffeic acid phenethyl ester (CAPE) counteracts DEX-induced osteoporosis. • CAPE hinders DEX-induced alterations in oxidation parameters as GSH, SOD and MDA. • CAPE opposes osteoclastogenesis via suppressing RANL/OPG ratio and Akt signals.

  10. Caffeic acid phenethyl ester protects against glucocorticoid-induced osteoporosis in vivo: Impact on oxidative stress and RANKL/OPG signals

    Energy Technology Data Exchange (ETDEWEB)

    Tolba, Mai F. [Department of Pharmacology and Toxicology, Faculty of Pharmacy, Ain Shams University, Cairo 11566 (Egypt); Chapman University, Irvine 92618, CA (United States); El-Serafi, Ahmed T. [Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272 (United Arab Emirates); Department of Medical Biochemistry, Faculty of Medicine, Suez Canal University, Ismailia (Egypt); Omar, Hany A., E-mail: hanyomar@sharjah.ac.ae [Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272 (United Arab Emirates); Department of Pharmacology, Faculty of Pharmacy, Beni-Suef University, Beni-Suef 62514 (Egypt)

    2017-06-01

    Glucocorticoid-induced osteoporosis (GIO) is one of the most common causes of secondary osteoporosis. Given that glucocorticoids are considered as a main component of the treatment protocols for a variety of inflammation and immune-mediated diseases besides its use as adjuvant to several chemotherapeutic agents, it is crucial to find ways to overcome this critical adverse effect. Caffeic acid phenethyl ester (CAPE), which is a natural compound derived from honeybee propolis displayed promising antiosteoporotic effects against mechanical bone injury in various studies. The current work aimed at investigating the potential protective effect of CAPE against GIO in vivo with emphasis on the modulation of oxidative status and receptor activator of NF-kB ligand (RANKL)/osteoprotegrin (OPG) signaling. The results showed that CAPE opposed dexamethasone (DEX)-mediated alterations in bone histology and tartarate-resistant acid phosphatase (TRAP) activity. In addition, CAPE restored oxidative balance, Runt-related transcription factor 2 (RunX2) expression and reduced caspase-3 activity in femur tissues. Co-administration of CAPE with DEX normalized RANKL/OPG ratio and Akt activation indicating a reduction in DEX-osteoclastogenesis. In conclusion, concurrent treatment of CAPE with DEX exhibited promising effects in the protection against DEX-induced osteoporosis through opposing osteoclastogenesis and protecting osteoblasts. The potent antioxidant activity of CAPE is, at least in part, involved in its anti-apoptotic effects and modulation of RunX2 and RANKL/OPG signals. The use of CAPE-enriched propolis formulas is strongly recommended for patients on chronic glucocorticoid therapy to help in the attenuation of GIO. - Highlights: • Caffeic acid phenethyl ester (CAPE) counteracts DEX-induced osteoporosis. • CAPE hinders DEX-induced alterations in oxidation parameters as GSH, SOD and MDA. • CAPE opposes osteoclastogenesis via suppressing RANL/OPG ratio and Akt signals.

  11. Inhibition of Procarcinogen Activating Enzyme CYP1A2 Activity and Free Radical Formation by Caffeic Acid and its Amide Analogues.

    Science.gov (United States)

    Narongchai, Paitoon; Niwatananun, Kanokporn; Narongchai, Siripun; Kusirisin, Winthana; Jaikang, Churdsak

    2016-01-01

    Caffeic acid (CAF) and its amide analogues, ethyl 1-(3',4'-dihydroxyphenyl) propen amide (EDPA), phenethyl 1-(3',4'-dihydroxyphenyl) propen amide (PEDPA), phenmethyl 1- (3',4'-dihydroxyphenyl) propen amide (PMDPA) and octyl 1-(3',4'-dihydroxyphenyl) propen amide (ODPA) were investigated for the inhibition of procarcinogen activating enzyme. CYP1A2 and scavenging activity on formation of nitric oxide, superoxide anion, DPPH radical and hydroxyl radical. It was found that they inhibited CYP1A2 enzyme by uncompetitive inhibition. Apparent Ki values of CAF, EDPA, PEDPA, PMDPA and ODPA were 0.59, 0.39, 0.45, 0.75 and 0.80 µM, respectively suggesting potent inhibitors of CYP1A2. Moreover, they potentially scavenged nitric oxide radical with IC 50 values of 0.12, 0.22, 0.28, 0.22 and 0.51 mM, respectively. The IC50 values of superoxide anion scavenging were 0.20, 0.22, 0.44, 2.18 and 2.50 mM, respectively. 1, 1- diphenyl-2- picrylhydrazyl (DPPH) radical-scavenging ability, shown as IC50 values, were 0.41, 0.29, 0.30, 0.89 and 0.84 mM, respectively. Moreover, the hydroxyl radical scavenging in vitro model was shown as IC50 values of 23.22, 21.06, 17.10, 17.21 and 15.81 µM, respectively. From our results, caffeic acid and its amide analogues are in vitro inhibitors of human CYP1A2 catalytic activity and free radical formation. They may be useful to be developed as potential chemopreventive agents that block CYP1A2-mediated chemical carcinogenesis.

  12. Catechol Groups Enable Reactive Oxygen Species Scavenging-Mediated Suppression of PKD-NFkappaB-IL-8 Signaling Pathway by Chlorogenic and Caffeic Acids in Human Intestinal Cells

    Directory of Open Access Journals (Sweden)

    Hee Soon Shin

    2017-02-01

    Full Text Available Chlorogenic acid (CHA and caffeic acid (CA are phenolic compounds found in coffee, which inhibit oxidative stress-induced interleukin (IL-8 production in intestinal epithelial cells, thereby suppressing serious cellular injury and inflammatory intestinal diseases. Therefore, we investigated the anti-inflammatory mechanism of CHA and CA, both of which inhibited hydrogen peroxide (H2O2-induced IL-8 transcriptional activity. They also significantly suppressed nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB transcriptional activity, nuclear translocation of the p65 subunit, and phosphorylation of IκB kinase (IKK. Additionally, upstream of IKK, protein kinase D (PKD was also suppressed. Finally, we found that they scavenged H2O2-induced reactive oxygen species (ROS and the functional moiety responsible for the anti-inflammatory effects of CHA and CA was the catechol group. Therefore, we conclude that the presence of catechol groups in CHA and CA allows scavenging of intracellular ROS, thereby inhibiting H2O2-induced IL-8 production via suppression of PKD-NF-κB signaling in human intestinal epithelial cells.

  13. Structure-Function Analyses of a Caffeic Acid O-Methyltransferase from Perennial Ryegrass Reveal the Molecular Basis for Substrate Preference[W][OA

    Science.gov (United States)

    Louie, Gordon V.; Bowman, Marianne E.; Tu, Yi; Mouradov, Aidyn; Spangenberg, German; Noel, Joseph P.

    2010-01-01

    Lignin forms from the polymerization of phenylpropanoid-derived building blocks (the monolignols), whose modification through hydroxylation and O-methylation modulates the chemical and physical properties of the lignin polymer. The enzyme caffeic acid O-methyltransferase (COMT) is central to lignin biosynthesis. It is often targeted in attempts to engineer the lignin composition of transgenic plants for improved forage digestibility, pulping efficiency, or utility in biofuel production. Despite intensive investigation, the structural determinants of the regiospecificity and substrate selectivity of COMT remain poorly defined. Reported here are x-ray crystallographic structures of perennial ryegrass (Lolium perenne) COMT (Lp OMT1) in open conformational state, apo- and holoenzyme forms and, most significantly, in a closed conformational state complexed with the products S-adenosyl-l-homocysteine and sinapaldehyde. The product-bound complex reveals the post-methyl-transfer organization of COMT’s catalytic groups with reactant molecules and the fully formed phenolic-ligand binding site. The core scaffold of the phenolic ligand forges a hydrogen-bonding network involving the 4-hydroxy group that anchors the aromatic ring and thereby permits only metahydroxyl groups to be positioned for transmethylation. While distal from the site of transmethylation, the propanoid tail substituent governs the kinetic preference of ryegrass COMT for aldehydes over alcohols and acids due to a single hydrogen bond donor for the C9 oxygenated moiety dictating the preference for an aldehyde. PMID:21177481

  14. Structure-function analyses of a caffeic acid O-methyltransferase from perennial ryegrass reveal the molecular basis for substrate preference.

    Science.gov (United States)

    Louie, Gordon V; Bowman, Marianne E; Tu, Yi; Mouradov, Aidyn; Spangenberg, German; Noel, Joseph P

    2010-12-01

    Lignin forms from the polymerization of phenylpropanoid-derived building blocks (the monolignols), whose modification through hydroxylation and O-methylation modulates the chemical and physical properties of the lignin polymer. The enzyme caffeic acid O-methyltransferase (COMT) is central to lignin biosynthesis. It is often targeted in attempts to engineer the lignin composition of transgenic plants for improved forage digestibility, pulping efficiency, or utility in biofuel production. Despite intensive investigation, the structural determinants of the regiospecificity and substrate selectivity of COMT remain poorly defined. Reported here are x-ray crystallographic structures of perennial ryegrass (Lolium perenne) COMT (Lp OMT1) in open conformational state, apo- and holoenzyme forms and, most significantly, in a closed conformational state complexed with the products S-adenosyl-L-homocysteine and sinapaldehyde. The product-bound complex reveals the post-methyl-transfer organization of COMT's catalytic groups with reactant molecules and the fully formed phenolic-ligand binding site. The core scaffold of the phenolic ligand forges a hydrogen-bonding network involving the 4-hydroxy group that anchors the aromatic ring and thereby permits only metahydroxyl groups to be positioned for transmethylation. While distal from the site of transmethylation, the propanoid tail substituent governs the kinetic preference of ryegrass COMT for aldehydes over alcohols and acids due to a single hydrogen bond donor for the C9 oxygenated moiety dictating the preference for an aldehyde.

  15. Caffeic Acid Phenethyl Ester Inhibits Oral Cancer Cell Metastasis by Regulating Matrix Metalloproteinase-2 and the Mitogen-Activated Protein Kinase Pathway

    Directory of Open Access Journals (Sweden)

    Chih-Yu Peng

    2012-01-01

    Full Text Available Caffeic acid phenethyl ester (CAPE, an active component extracted from honeybee hives, exhibits anti-inflammatory and anticancer activities. However, the molecular mechanism by which CAPE affects oral cancer cell metastasis has yet to be elucidated. In this study, we investigated the potential mechanisms underlying the effects of CAPE on the invasive ability of SCC-9 oral cancer cells. Results showed that CAPE attenuated SCC-9 cell migration and invasion at noncytotoxic concentrations (0 μM to 40 μM. Western blot and gelatin zymography analysis findings further indicated that CAPE downregulated matrix metalloproteinase-2 (MMP-2 protein expression and inhibited its enzymatic activity. CAPE exerted its inhibitory effects on MMP-2 expression and activity by upregulating tissue inhibitor of metalloproteinase-2 (TIMP-2 and potently decreased migration by reducing focal adhesion kinase (FAK phosphorylation and the activation of its downstream signaling molecules p38/MAPK and JNK. These data indicate that CAPE could potentially be used as a chemoagent to prevent oral cancer metastasis.

  16. Caffeic Acid Phenethyl Ester and Ethanol Extract of Propolis Induce the Complementary Cytotoxic Effect on Triple-Negative Breast Cancer Cell Lines

    Directory of Open Access Journals (Sweden)

    Anna Rzepecka-Stojko

    2015-05-01

    Full Text Available Chemotherapy of breast cancer could be improved by bioactive natural substances, which may potentially sensitize the carcinoma cells’ susceptibility to drugs. Numerous phytochemicals, including propolis, have been reported to interfere with the viability of carcinoma cells. We evaluated the in vitro cytotoxic activity of ethanol extract of propolis (EEP and its derivative caffeic acid phenethyl ester (CAPE towards two triple-negative breast cancer (TNBC cell lines, MDA-MB-231 and Hs578T, by implementation of the MTT and lactate dehydrogenase (LDH assays. The morphological changes of breast carcinoma cells were observed following exposure to EEP and CAPE. The IC50 of EEP was 48.35 µg∙mL−1 for MDA-MB-23 cells and 33.68 µg∙mL−1 for Hs578T cells, whereas the CAPE IC50 was 14.08 µM and 8.01 µM for the MDA-MB-231 and Hs578T cell line, respectively. Here, we report that propolis and CAPE inhibited the growth of the MDA-MB-231 and Hs578T lines in a dose-dependent and exposure time-dependent manner. EEP showed less cytotoxic activity against both types of TNBC cells. EEP and, particularly, CAPE may markedly affect the viability of breast cancer cells, suggesting the potential role of bioactive compounds in chemoprevention/chemotherapy by potentiating the action of standard anti-cancer drugs.

  17. Caffeic acid phenethyl ester inhibits 3-MC-induced CYP1A1 expression through induction of hypoxia-inducible factor-1α

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung Gyun [Department of Toxicology, College of Pharmacy, Chungnam National University, Daejeon (Korea, Republic of); Han, Eun Hee [Division of Life Science, Korea Basic Science Institute, Daejeon (Korea, Republic of); Im, Ji Hye; Lee, Eun Ji; Jin, Sun Woo [Department of Toxicology, College of Pharmacy, Chungnam National University, Daejeon (Korea, Republic of); Jeong, Hye Gwang, E-mail: hgjeong@cnu.ac.kr [Department of Toxicology, College of Pharmacy, Chungnam National University, Daejeon (Korea, Republic of)

    2015-09-25

    Caffeic acid phenethyl ester (CAPE), a natural component of propolis, is reported to have anticarcinogenic properties, although its precise chemopreventive mechanism remains unclear. In this study, we examined the effects of CAPE on 3-methylcholanthrene (3-MC)-induced CYP1A1 expression and activities. CAPE reduced the formation of the benzo[a]pyrene-DNA adduct. Moreover, CAPE inhibited 3-MC-induced CYP1A1 activity, mRNA expression, protein level, and promoter activity. CAPE treatment also decreased 3-MC-inducible xenobiotic-response element (XRE)-linked luciferase, aryl hydrocarbons receptor (AhR) transactivation and nuclear localization. CAPE induced hypoxia inducible factor-1α (HIF-1α) protein level and HIF-1α responsible element (HRE) transcriptional activity. CAPE-mediated HIF-1α reduced 3-MC-inducible CYP1A1 protein expression. Taken together, CAPE decreases 3-MC-mediated CYP1A1 expression, and this inhibitory response is associated with inhibition of AhR and HIF-1α induction. - Highlights: • CAPE reduced the formation of the benzo[a]pyrene-DNA adduct. • CAPE inhibited 3-MC-induced CYP1A1 expression. • CAPE induced HIF-1α induction. • CAPE-mediated HIF-1α reduced 3-MC-inducible CYP1A1 expression.

  18. Development of novel antibacterial active, HaCaT biocompatible and biodegradable CA-g-P(3HB-EC biocomposites with caffeic acid as a functional entity

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    H. M. N. Iqbal

    2015-09-01

    Full Text Available We have developed novel composites by grafting caffeic acid (CA onto the P(3HB-EC based material and laccase from Trametes versicolor was used for grafting purposes. The resulting composites were designated as CA-g-P(3HB-EC i.e., P(3HB-EC (control, 5CA-g-P(3HB-EC, 10CA-g-P(3HB-EC, 15CA-g-P(3HB-EC and 20CA-g-P(3HB-EC. FT-IR (Fourier-transform infrared spectroscopy was used to examine the functional and elemental groups of the control and laccase-assisted graft composites. Evidently, 15CA-g-P(3HB-EC composite exhibited resilient antibacterial activity against Gram-positive and Gram-negative bacterial strains. Moreover, a significant level of biocompatibility and biodegradability of the CA-g-P(3HB-EC composites was also achieved with the human keratinocytes-like HaCaT cells and soil burial evaluation, respectively. In conclusion, the newly developed novel composites with multi characteristics could well represent the new wave of biomaterials for medical applications, and more specifically have promising future in the infection free would dressings, burn and/or skin regeneration field due to their sophisticated characteristics.

  19. Protective Effect of Caffeic Acid on Paclitaxel Induced Anti-Proliferation and Apoptosis of Lung Cancer Cells Involves NF-κB Pathway

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    Yao Fong

    2012-05-01

    Full Text Available Caffeic acid (CA, a natural phenolic compound, is abundant in medicinal plants. CA possesses multiple biological effects such as anti-bacterial and anti-cancer growth. CA was also reported to induce fore stomach and kidney tumors in a mouse model. Here we used two human lung cancer cell lines, A549 and H1299, to clarify the role of CA in cancer cell proliferation. The growth assay showed that CA moderately promoted the proliferation of the lung cancer cells. Furthermore, pre-treatment of CA rescues the proliferation inhibition induced by a sub-IC50 dose of paclitaxel (PTX, an anticancer drug. Western blot showed that CA up-regulated the pro-survival proteins survivin and Bcl-2, the down-stream targets of NF-κB. This is consistent with the observation that CA induced nuclear translocation of NF-κB p65. Our study suggested that the pro-survival effect of CA on PTX-treated lung cancer cells is mediated through a NF-κB signaling pathway. This may provide mechanistic insights into the chemoresistance of cancer calls.

  20. Evaluation of the effect of Chrysin and Caffeic acid phenethyl ester on eIF4E expression in AGS cell line

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    Abolhasani Marziyeh

    2014-04-01

    Full Text Available Introduction: The Ras/Akt/mTORC1 signal transduction pathways play a critical role in regulating translation and converge on initiation factor eukaryotic translation initiation factor 4E (eIF4E which is overexpressed in various malignancies. In the current study we aimed to assess the effect of chrysin and caffeic acid phenethyl ester (CAPE on eIF4E expression level in human stomach cancer AGS cell line. Methods: AGS cells were treated with 15, 20, 30 and 40 μM concentration of chrysin and CAPE separately, then eIF4E expression was evaluated in treated cells using real time-PCR method. Results: A significant decrease in eIF4E expression in the cells following 40 μM chrysin treatment was observed (p<0.05. There was a significant decrease in CAPE-treated cells in a dose dependent manner. Indeed the cells treated with 30 and 40 μM concentrations of CAPE, showed a significant decline in eIF4E expression (p<0.05. Conclusion: Our results suggest that CAPE and chrysin may be useful as a potential therapeutic agent for treatment of gastric cancers with an elevated eIF4E expression level.

  1. Determination of the Structure and Catalytic Mechanism of Sorghum bicolor Caffeic Acid O-Methyltransferase and the Structural Impact of Three brown midrib12 Mutations1[W

    Science.gov (United States)

    Green, Abigail R.; Lewis, Kevin M.; Barr, John T.; Jones, Jeffrey P.; Lu, Fachuang; Ralph, John; Vermerris, Wilfred; Sattler, Scott E.; Kang, ChulHee

    2014-01-01

    Using S-adenosyl-methionine as the methyl donor, caffeic acid O-methyltransferase from sorghum (Sorghum bicolor; SbCOMT) methylates the 5-hydroxyl group of its preferred substrate, 5-hydroxyconiferaldehyde. In order to determine the mechanism of SbCOMT and understand the observed reduction in the lignin syringyl-to-guaiacyl ratio of three brown midrib12 mutants that carry COMT gene missense mutations, we determined the apo-form and S-adenosyl-methionine binary complex SbCOMT crystal structures and established the ternary complex structure with 5-hydroxyconiferaldehyde by molecular modeling. These structures revealed many features shared with monocot ryegrass (Lolium perenne) and dicot alfalfa (Medicago sativa) COMTs. SbCOMT steady-state kinetic and calorimetric data suggest a random bi-bi mechanism. Based on our structural, kinetic, and thermodynamic results, we propose that the observed reactivity hierarchy among 4,5-dihydroxy-3-methoxycinnamyl (and 3,4-dihydroxycinnamyl) aldehyde, alcohol, and acid substrates arises from the ability of the aldehyde to stabilize the anionic intermediate that results from deprotonation of the 5-hydroxyl group by histidine-267. Additionally, despite the presence of other phenylpropanoid substrates in vivo, sinapaldehyde is the preferential product, as demonstrated by its low Km for 5-hydroxyconiferaldehyde. Unlike its acid and alcohol substrates, the aldehydes exhibit product inhibition, and we propose that this is due to nonproductive binding of the S-cis-form of the aldehydes inhibiting productive binding of the S-trans-form. The S-cis-aldehydes most likely act only as inhibitors, because the high rotational energy barrier around the 2-propenyl bond prevents S-trans-conversion, unlike alcohol substrates, whose low 2-propenyl bond rotational energy barrier enables rapid S-cis/S-trans-interconversion. PMID:24948836

  2. Determination of the Structure and Catalytic Mechanism of Sorghum bicolor Caffeic Acid O-Methyltransferase and the Structural Impact of Three brown midrib12 Mutations.

    Science.gov (United States)

    Green, Abigail R; Lewis, Kevin M; Barr, John T; Jones, Jeffrey P; Lu, Fachuang; Ralph, John; Vermerris, Wilfred; Sattler, Scott E; Kang, ChulHee

    2014-08-01

    Using S-adenosyl-methionine as the methyl donor, caffeic acid O-methyltransferase from sorghum (Sorghum bicolor; SbCOMT) methylates the 5-hydroxyl group of its preferred substrate, 5-hydroxyconiferaldehyde. In order to determine the mechanism of SbCOMT and understand the observed reduction in the lignin syringyl-to-guaiacyl ratio of three brown midrib12 mutants that carry COMT gene missense mutations, we determined the apo-form and S-adenosyl-methionine binary complex SbCOMT crystal structures and established the ternary complex structure with 5-hydroxyconiferaldehyde by molecular modeling. These structures revealed many features shared with monocot ryegrass (Lolium perenne) and dicot alfalfa (Medicago sativa) COMTs. SbCOMT steady-state kinetic and calorimetric data suggest a random bi-bi mechanism. Based on our structural, kinetic, and thermodynamic results, we propose that the observed reactivity hierarchy among 4,5-dihydroxy-3-methoxycinnamyl (and 3,4-dihydroxycinnamyl) aldehyde, alcohol, and acid substrates arises from the ability of the aldehyde to stabilize the anionic intermediate that results from deprotonation of the 5-hydroxyl group by histidine-267. Additionally, despite the presence of other phenylpropanoid substrates in vivo, sinapaldehyde is the preferential product, as demonstrated by its low K m for 5-hydroxyconiferaldehyde. Unlike its acid and alcohol substrates, the aldehydes exhibit product inhibition, and we propose that this is due to nonproductive binding of the S-cis-form of the aldehydes inhibiting productive binding of the S-trans-form. The S-cis-aldehydes most likely act only as inhibitors, because the high rotational energy barrier around the 2-propenyl bond prevents S-trans-conversion, unlike alcohol substrates, whose low 2-propenyl bond rotational energy barrier enables rapid S-cis/S-trans-interconversion. © 2014 American Society of Plant Biologists. All Rights Reserved.

  3. Caffeic acid attenuates the inflammatory stress induced by glycated LDL in human endothelial cells by mechanisms involving inhibition of AGE-receptor, oxidative, and endoplasmic reticulum stress.

    Science.gov (United States)

    Toma, Laura; Sanda, Gabriela M; Niculescu, Loredan S; Deleanu, Mariana; Stancu, Camelia S; Sima, Anca V

    2017-09-10

    Type 2 diabetes mellitus is a worldwide epidemic and its atherosclerotic complications determine the high morbidity and mortality of diabetic patients. Caffeic acid (CAF), a phenolic acid present in normal diets, is known for its antioxidant properties. The aim of this study was to investigate CAF's anti-inflammatory properties and its mechanism of action, using cultured human endothelial cells (HEC) incubated with glycated low-density lipoproteins (gLDL). Levels of the receptor for advanced glycation end-products (RAGE), inflammatory stress markers (C reactive protein, CRP; vascular cell adhesion molecule-1, VCAM-1; monocyte chemoattractant protein-1, MCP-1), and oxidative stress and endoplasmic reticulum stress (ERS) markers were evaluated in gLDL-exposed HEC, in the presence/absence of CAF. RAGE silencing or blocking, specific inhibitors for oxidative stress (apocynin, N-acetyl-cysteine), and ERS (salubrinal) were used. The results showed that: (i) gLDL induced CRP synthesis and secretion through mechanisms involving NADPH oxidase-dependent oxidative stress and ERS in HEC; (ii) gLDL-RAGE interaction, oxidative stress, and ERS stimulated the secretion of VCAM-1 and MCP-1 in HEC; and (iii) CAF reduced the secretion of CRP, VCAM-1, and MCP-1 in gLDL-exposed HEC by inhibiting RAGE expression, oxidative stress, and ERS. In conclusion, CAF might be a promising alternative to ameliorate a wide spectrum of disorders due to its complex mechanisms of action resulting in anti-inflammatory and antioxidative properties. © 2017 BioFactors, 43(5):685-697, 2017. © 2017 International Union of Biochemistry and Molecular Biology.

  4. Establishment of Hairy Root Cultures of Rhaponticum carthamoides (Willd. Iljin for the Production of Biomass and Caffeic Acid Derivatives

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    Ewa Skała

    2015-01-01

    Full Text Available The aim of the study was to obtain transformed roots of Rhaponticum carthamoides and evaluate their phytochemical profile. Hairy roots were induced from leaf explants by the transformation of Agrobacterium rhizogenes strains A4 and ATCC 15834. The best response (43% was achieved by infection with A4 strain. The effects of different liquid media (WPM, B5, SH with full and half-strength concentrations of macro- and micronutrients on biomass accumulation of the best grown hairy root line (RC3 at two different lighting conditions (light or dark were investigated. The highest biomass (93 g L−1 of the fresh weight after 35 days was obtained in WPM medium under periodic light. UPLC-PDA-ESI-MS3 and HPLC-PDA analyses of 80% aqueous methanol extracts from the obtained hairy roots revealed the presence of eleven caffeoylquinic acids and their derivatives and five flavonoid glycosides. The production of caffeoylquinic acids and their derivatives was elevated in hairy roots grown in the light. Only light-grown hairy roots demonstrated the capability for the biosynthesis of such flavonoid glycosides as quercetagetin, quercetin, luteolin, and patuletin hexosides. Chlorogenic acid, 3,5-di-O-caffeoylquinic acid and a tentatively identified tricaffeoylquinic acid derivative were detected as the major compounds present in the transformed roots.

  5. An unusual caffeic acid derived bicyclic [2.2.2] octane lignan and other constituents from Cordia rufescens.

    Science.gov (United States)

    do Vale, Ademir E; David, Jorge M; dos Santos, Edlene O; David, Juceni P; e Silva, Lidercia C R C; Bahia, Marcus V; Brandão, Hugo N

    2012-04-01

    This work reports isolation of an unusual lignan with a bicyclic [2.2.2] octene skeleton, named rufescenolide (1), from stems of Cordia rufescens, along with β-sitosterol, stigmasterol, syringaldehyde, 3-β-O-D-glucopyranosyl-sitosterol, methyl caffeate, 4-methoxy-protocatechuic acid and methyl rosmarinate. Structural characterizations employed IR spectroscopic, ESIHRMS and mono and dimensional NMR spectroscopy. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Nitrogen Limited Red and Green Leaf Lettuce Accumulate Flavonoid Glycosides, Caffeic Acid Derivatives, and Sucrose while Losing Chlorophylls, Β-Carotene and Xanthophylls.

    Science.gov (United States)

    Becker, Christine; Urlić, Branimir; Jukić Špika, Maja; Kläring, Hans-Peter; Krumbein, Angelika; Baldermann, Susanne; Goreta Ban, Smiljana; Perica, Slavko; Schwarz, Dietmar

    2015-01-01

    Reduction of nitrogen application in crop production is desirable for ecological and health-related reasons. Interestingly, nitrogen deficiency can lead to enhanced concentrations of polyphenols in plants. The reason for this is still under discussion. The plants' response to low nitrogen concentration can interact with other factors, for example radiation intensity. We cultivated red and green leaf lettuce hydroponically in a Mediterranean greenhouse, supplying three different levels of nitrogen (12 mM, 3 mM, 0.75 mM), either in full or reduced (-50%) radiation intensity. In both red and green lettuce, we found clear effects of the nitrogen treatments on growth characteristics, phenolic and photosynthetic compounds, nitrogen, nitrate and carbon concentration of the plants. Interestingly, the concentrations of all main flavonoid glycosides, caffeic acid derivatives, and sucrose increased with decreasing nitrogen concentration, whereas those of chlorophylls, β-carotene, neoxanthin, lactucaxanthin, all trans- and cis-violaxanthin decreased. The constitutive concentrations of polyphenols were lower in the green cultivar, but their relative increase was more pronounced than in the red cultivar. The constitutive concentrations of chlorophylls, β-carotene, neoxanthin, all trans- and cis-violaxanthin were similar in red and green lettuce and with decreasing nitrogen concentration they declined to a similar extent in both cultivars. We only detected little influence of the radiation treatments, e.g. on anthocyanin concentration, and hardly any interaction between radiation and nitrogen concentration. Our results imply a greater physiological plasticity of green compared to the red lettuce regarding its phenolic compounds. They support the photoprotection theory regarding anthocyanins as well as the theory that the deamination activity of phenylalanine ammonia-lyase drives phenylpropanoid synthesis.

  7. Nitrogen Limited Red and Green Leaf Lettuce Accumulate Flavonoid Glycosides, Caffeic Acid Derivatives, and Sucrose while Losing Chlorophylls, Β-Carotene and Xanthophylls

    Science.gov (United States)

    Becker, Christine; Urlić, Branimir; Jukić Špika, Maja; Kläring, Hans-Peter; Krumbein, Angelika; Baldermann, Susanne; Goreta Ban, Smiljana; Perica, Slavko; Schwarz, Dietmar

    2015-01-01

    Reduction of nitrogen application in crop production is desirable for ecological and health-related reasons. Interestingly, nitrogen deficiency can lead to enhanced concentrations of polyphenols in plants. The reason for this is still under discussion. The plants’ response to low nitrogen concentration can interact with other factors, for example radiation intensity. We cultivated red and green leaf lettuce hydroponically in a Mediterranean greenhouse, supplying three different levels of nitrogen (12 mM, 3 mM, 0.75 mM), either in full or reduced (-50%) radiation intensity. In both red and green lettuce, we found clear effects of the nitrogen treatments on growth characteristics, phenolic and photosynthetic compounds, nitrogen, nitrate and carbon concentration of the plants. Interestingly, the concentrations of all main flavonoid glycosides, caffeic acid derivatives, and sucrose increased with decreasing nitrogen concentration, whereas those of chlorophylls, β-carotene, neoxanthin, lactucaxanthin, all trans- and cis-violaxanthin decreased. The constitutive concentrations of polyphenols were lower in the green cultivar, but their relative increase was more pronounced than in the red cultivar. The constitutive concentrations of chlorophylls, β-carotene, neoxanthin, all trans- and cis-violaxanthin were similar in red and green lettuce and with decreasing nitrogen concentration they declined to a similar extent in both cultivars. We only detected little influence of the radiation treatments, e.g. on anthocyanin concentration, and hardly any interaction between radiation and nitrogen concentration. Our results imply a greater physiological plasticity of green compared to the red lettuce regarding its phenolic compounds. They support the photoprotection theory regarding anthocyanins as well as the theory that the deamination activity of phenylalanine ammonia-lyase drives phenylpropanoid synthesis. PMID:26569488

  8. Caffeic acid, a phenol found in white wine, modulates endothelial nitric oxide production and protects from oxidative stress-associated endothelial cell injury.

    Directory of Open Access Journals (Sweden)

    Massimiliano Migliori

    Full Text Available Several studies demonstrated that endothelium dependent vasodilatation is impaired in cardiovascular and chronic kidney diseases because of oxidant stress-induced nitric oxide availability reduction. The Mediterranean diet, which is characterized by food containing phenols, was correlated with a reduced incidence of cardiovascular diseases and delayed progression toward end stage chronic renal failure. Previous studies demonstrated that both red and white wine exert cardioprotective effects. In particular, wine contains Caffeic acid (CAF, an active component with known antioxidant activities.The aim of the present study was to investigate the protective effect of low doses of CAF on oxidative stress-induced endothelial injury.CAF increased basal as well as acetylcholine-induced NO release by a mechanism independent from eNOS expression and phosphorylation. In addition, low doses of CAF (100 nM and 1 μM increased proliferation and angiogenesis and inhibited leukocyte adhesion and endothelial cell apoptosis induced by hypoxia or by the uremic toxins ADMA, p-cresyl sulfate and indoxyl sulfate. The biological effects exerted by CAF on endothelial cells may be at least in part ascribed to modulation of NO release and by decreased ROS production. In an experimental model of kidney ischemia-reperfusion injury in mice, CAF significantly decreased tubular cell apoptosis, intraluminal cast deposition and leukocyte infiltration.The results of the present study suggest that CAF, at very low dosages similar to those observed after moderate white wine consumption, may exert a protective effect on endothelial cell function by modulating NO release independently from eNOS expression and phosphorylation. CAF-induced NO modulation may limit cardiovascular and kidney disease progression associated with oxidative stress-mediated endothelial injury.

  9. Chloroplast overexpression of rice caffeic acid O-methyltransferase increases melatonin production in chloroplasts via the 5-methoxytryptamine pathway in transgenic rice plants.

    Science.gov (United States)

    Choi, Geun-Hee; Lee, Hyoung Yool; Back, Kyoungwhan

    2017-08-01

    Recent analyses of the enzymatic features of various melatonin biosynthetic genes from bacteria, animals, and plants have led to the hypothesis that melatonin could be synthesized via the 5-methoxytryptamine (5-MT) pathway. 5-MT is known to be synthesized in vitro from serotonin by the enzymatic action of O-methyltransferases, including N-acetylserotonin methyltransferase (ASMT) and caffeic acid O-methyltransferase (COMT), leading to melatonin synthesis by the subsequent enzymatic reaction with serotonin N-acetyltransferase (SNAT). Here, we show that 5-MT was produced and served as a precursor for melatonin synthesis in plants. When rice seedlings were challenged with senescence treatment, 5-MT levels and melatonin production were increased in transgenic rice seedlings overexpressing the rice COMT in chloroplasts, while no such increases were observed in wild-type or transgenic seedlings overexpressing the rice COMT in the cytosol, suggesting a 5-MT transport limitation from the cytosol to chloroplasts. In contrast, cadmium treatment led to results different from those in senescence. The enhanced melatonin production was not observed in the chloroplast COMT lines relative over the cytosol COMT lines although 5-MT levels were equally induced in all genotypes upon cadmium treatment. The transgenic seedlings with enhanced melatonin in their chloroplasts exhibited improved seedling growth vs the wild type under continuous light conditions. This is the first report describing enhanced melatonin production in chloroplasts via the 5-MT pathway with the ectopic overexpression of COMT in chloroplasts in plants. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Nitrogen Limited Red and Green Leaf Lettuce Accumulate Flavonoid Glycosides, Caffeic Acid Derivatives, and Sucrose while Losing Chlorophylls, Β-Carotene and Xanthophylls.

    Directory of Open Access Journals (Sweden)

    Christine Becker

    Full Text Available Reduction of nitrogen application in crop production is desirable for ecological and health-related reasons. Interestingly, nitrogen deficiency can lead to enhanced concentrations of polyphenols in plants. The reason for this is still under discussion. The plants' response to low nitrogen concentration can interact with other factors, for example radiation intensity. We cultivated red and green leaf lettuce hydroponically in a Mediterranean greenhouse, supplying three different levels of nitrogen (12 mM, 3 mM, 0.75 mM, either in full or reduced (-50% radiation intensity. In both red and green lettuce, we found clear effects of the nitrogen treatments on growth characteristics, phenolic and photosynthetic compounds, nitrogen, nitrate and carbon concentration of the plants. Interestingly, the concentrations of all main flavonoid glycosides, caffeic acid derivatives, and sucrose increased with decreasing nitrogen concentration, whereas those of chlorophylls, β-carotene, neoxanthin, lactucaxanthin, all trans- and cis-violaxanthin decreased. The constitutive concentrations of polyphenols were lower in the green cultivar, but their relative increase was more pronounced than in the red cultivar. The constitutive concentrations of chlorophylls, β-carotene, neoxanthin, all trans- and cis-violaxanthin were similar in red and green lettuce and with decreasing nitrogen concentration they declined to a similar extent in both cultivars. We only detected little influence of the radiation treatments, e.g. on anthocyanin concentration, and hardly any interaction between radiation and nitrogen concentration. Our results imply a greater physiological plasticity of green compared to the red lettuce regarding its phenolic compounds. They support the photoprotection theory regarding anthocyanins as well as the theory that the deamination activity of phenylalanine ammonia-lyase drives phenylpropanoid synthesis.

  11. Human proton coupled folic acid transporter is a monodisperse oligomer in the lauryl maltose neopentyl glycol solubilized state.

    Science.gov (United States)

    Aduri, Nanda G; Ernst, Heidi A; Prabhala, Bala K; Bhatt, Shweta; Boesen, Thomas; Gajhede, Michael; Mirza, Osman

    2018-01-08

    The human proton coupled folic acid transporter PCFT is the major import route for dietary folates. Mutations in the gene encoding PCFT cause hereditary folic acid malabsorption, which manifests itself by compromised folate absorption from the intestine and also in impaired folate transport into the central nervous system. Since its recent discovery, PCFT has been the subject of numerous biochemical studies aiming at understanding its structure and mechanism. One major focus has been its oligomeric state, with some reports supporting oligomers and others a monomer. Here, we report the overexpression and purification of recombinant PCFT. Following detergent screening, n-Dodecyl β-D-maltoside (DDM) and lauryl maltose neopentyl glycol (LMNG) were chosen for further work as they exhibited the most optimal solubilization. We found that purified detergent solubilized PCFT was able to bind folic acid, thus indicating a functionally active protein. Size exclusion chromatography showed that PCFT in DDM was polydisperse; the LMNG preparation was clearly monodisperse but with shorter retention time than the major DDM peak. To assess the oligomeric state negative stain electron microscopy was performed which showed a particle with the size of a PCFT dimer. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Preparation and characterization of dutasteride-loaded nanostructured lipid carriers coated with stearic acid-chitosan oligomer for topical delivery.

    Science.gov (United States)

    Noor, Norhayati Mohamed; Sheikh, Khalid; Somavarapu, Satyanarayana; Taylor, Kevin M G

    2017-08-01

    Dutasteride, used for treating benign prostate hyperplasia (BPH), promotes hair growth. To enhance delivery to the hair follicles and reduce systemic effects, in this study dutasteride has been formulated for topical application, in a nanostructured lipid carrier (NLC) coated with chitosan oligomer-stearic acid (CSO-SA). CSO-SA has been successfully synthesized, as confirmed using 1 H NMR and FTIR. Formulation of dutasteride-loaded nanostructured lipid carriers (DST-NLCs) was optimized using a 2 3 full factorial design. This formulation was coated with different concentrations of stearic acid-chitosan solution. Coating DST-NLCs with 5% SA-CSO increased mean size from 187.6±7.0nm to 220.1±11.9nm, and modified surface charge, with zeta potentials being -18.3±0.9mV and +25.8±1.1mV for uncoated and coated DST-NLCs respectively. Transmission electron microscopy showed all formulations comprised approximately spherical particles. DST-NLCs, coated and uncoated with CSO-SA, exhibited particle size stability over 60days, when stored at 4-8°C. However, NLCs coated with CSO (without conjugation) showed aggregation when stored at 4-8°C after 30days. The measured particle size for all formulations stored at 25°C suggested aggregation, which was greatest for DST-NLCs coated with 10% CSO-SA and 5% CSO. All nanoparticle formulations exhibited rapid release in an in vitro release study, with uncoated NLCs exhibiting the fastest release rate. Using a Franz diffusion cell, no dutasteride permeated through pig ear skin after 48h, such that it was not detected in the receptor chamber for all samples. The amount of dutasteride in the skin was significantly different (pchitosan conjugate was successfully prepared, and modified the surface charge of DST-NLCs from negative to positive. These stable, less cytotoxic, positively-charged dutasteride-loaded nanostructured lipid carriers, with stearic acid-chitosan oligomer conjugate, are appropriate for topical delivery and have

  13. Caffeic acid phenethyl ester induced cell cycle arrest and growth inhibition in androgen-independent prostate cancer cells via regulation of Skp2, p53, p21Cip1 and p27Kip1

    OpenAIRE

    Lin, Hui-Ping; Lin, Ching-Yu; Huo, Chieh; Hsiao, Ping-Hsuan; Su, Liang-Cheng; Jiang, Shih Sheng; Chan, Tzu-Min; Chang, Chung-Ho; Chen, Li-Tzong; Kung, Hsing-Jien; Wang, Horng-Dar; Chuu, Chih-Pin

    2015-01-01

    Prostate cancer (PCa) patients receiving the androgen ablation therapy ultimately develop recurrent castration-resistant prostate cancer (CRPC) within 1?3 years. Treatment with caffeic acid phenethyl ester (CAPE) suppressed cell survival and proliferation via induction of G1 or G2/M cell cycle arrest in LNCaP 104-R1, DU-145, 22Rv1, and C4?2 CRPC cells. CAPE treatment also inhibited soft agar colony formation and retarded nude mice xenograft growth of LNCaP 104-R1 cells. We identified that CAP...

  14. Sulfated caffeic acid dehydropolymer attenuates elastase and cigarette smoke extract-induced emphysema in rats: sustained activity and a need of pulmonary delivery.

    Science.gov (United States)

    Saluja, Bhawana; Li, Hua; Desai, Umesh R; Voelkel, Norbert F; Sakagami, Masahiro

    2014-08-01

    Although emphysema destroys alveolar structures progressively and causes death eventually, no drug has been discovered to prevent, intervene, and/or resolve this life-threatening disease. We recently reported that sulfated caffeic acid dehydropolymer CDSO3 is a novel potent triple-action inhibitor of elastolysis, oxidation, and inflammation in vitro, and therefore, a potential anti-emphysema agent. However, the in vivo therapeutic potency, duration and mode of actions, and effective route remain to be demonstrated. Emphysema was induced in rats with human sputum elastase (HSE) combined with cigarette smoke extract (CSE). CDSO3 at 5, 30, or 100 μg/kg was dosed to the lung or injected subcutaneously at 2, 6, or 24 h before or 1 or 24 h or 1 week after the HSE/CSE instillation. At 1 h or 48 h or on day 21-22 or day 28, lungs were examined for airway-to-blood injurious barrier damage; their elastolytic, oxidative, and inflammatory activities; lung luminal leukocytes infiltration; functional treadmill exercise endurance; and/or morphological airspace enlargement. CDSO3, when dosed to the lung at 30 or 100 μg/kg, but not via systemic subcutaneous injection, significantly (43-93 %) attenuated HSE/CSE-induced (1) barrier damage measured by luminal hemorrhage and protein leak; (2) elastolytic, oxidative, and inflammatory activities measured with elastase, reduced glutathione, and TNFα levels, respectively; (3) luminal neutrophil infiltration and tissue myeloperoxidase activity; (4) functional impairment of exercise endurance; and (5) airspace enlargement, in both preventive and interventional dosing protocols. Notably, the effects were shown to last for 24 h at the greater 100-μg/kg dose, and the 1-week-delayed administration was also capable of attenuating the development of emphysema. CDSO3 is a novel, potent, long-acting, nonpeptidic macromolecule that inhibits HSE/CSE-induced elastolysis, oxidation, and inflammation in the lung and thereby attenuates the development

  15. Ameliorating Role of Caffeic Acid Phenethyl Ester (CAPE Against Methotrexate-Induced Oxidative Stress in the Sciatic Nerve, Spinal Cord and Brain Stem Tissues of Rats

    Directory of Open Access Journals (Sweden)

    Ertuğrul Uzar

    2010-03-01

    Full Text Available OBJECTIVE: Methotrexate (MTX-associated neurotoxicity is an important clinical problem in cancer patients, but the mechanisms of MTX-induced neurotoxicity are not yet known exactly. The aims of this study were (1 to investigate the possible role of malondialdehyde (MDA, superoxide dismutase (SOD enzyme, glutathione peroxidase (GSH-Px and catalase (CAT in the pathogenesis of MTX-induced neurotoxicity and (2 to determine whether there is a putative protective effect of caffeic acid phenethyl ester (CAPE on MTX-induced neurotoxicity in the spinal cord, brainstem and sciatic nerve of rats. METHODS: A total of 19 adult Wistar male rats were divided into three experimental groups. Group I, control group; Group II, MTX-treated group; and Group III, MTX + CAPE-treated group. MTX was administered to the MTX and MTX + CAPE groups intraperitoneally (IP with a single dose of 20 mg/kg on the second day of the experiment. CAPE was administered to the MTX + CAPE group IP with a dose of 10 μmol/kg for 7 days. RESULTS: In the sciatic nerve and spinal cord tissue, CAT and GSH-Px activities were increased in the MTX group in comparison with the control group. CAPE treatment with MTX significantly decreased CAT and GSH-Px activities in the neuronal tissues of rats in comparison with the MTX group. In the spinal cord and brainstem tissues, SOD activity in the MTX group was decreased in comparison with the control group, but in the sciatic nerve, there was no significant difference. In the spinal cord and brainstem of rats, SOD activity was increased in the CAPE + MTX group when compared with the MTX group. The level of MDA was higher in the MTX group than in the control group. CAPE administration with MTX injection caused a significant decrease in MDA level when compared with the MTX group. CONCLUSION: These results reveal that MTX increases oxidative stress in the sciatic nerve, spinal cord and brainstem of rats and that CAPE has a preventive effect on the

  16. Protective Effect of Combined Caffeic Acid Phenethyl Ester and Bevacizumab Against Hydrogen Peroxide-Induced Oxidative Stress in Human RPE Cells.

    Science.gov (United States)

    Dinc, Erdem; Ayaz, Lokman; Kurt, Akif Hakan

    2017-12-01

    This study aimed to evaluate the protective effects of caffeic acid phenethyl ester (CAPE) and combined CAPE-bevacizumab against oxidative stress induced by hydrogen peroxide (H 2 O 2 ) in human retinal pigment epithelium. ARPE-19 cells were pretreated with 5, 10, and 30 μM CAPE alone and in combination with bevacizumab for 3 h, then exposed to H 2 O 2 for 16 h. Cell viability was evaluated with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Vascular endothelial growth factor (VEGF) protein levels in the medium were measured using a human VEGF ELISA kit. Total antioxidant status (TAS) and total oxidant status (TOS) were measured in ARPE-19 cells using the test kit from Rel Assay. Expression levels of VEGF, Bax, Bcl-2, cytochrome c, apoptotic protease activating factor-1 (apaf-1), and caspase-3 were determined using reverse transcription polymerase chain reaction. Pretreatment of ARPE-19 cells with 30 μM CAPE and combined CAPE-bevacizumab reduced H 2 O 2 mediated cell death. H 2 O 2 -induced oxidative stress increased TOS and VEGF production, which was significantly inhibited by CAPE and the CAPE-bevacizumab combination. VEGF, Bax, cytochrome c, apaf-1, and caspase-3 gene expressions were significantly decreased in cells pretreated with 5, 10, and 30 μM CAPE and combined CAPE-bevacizumab compared to the H 2 O 2 group. In addition, Bcl-2 expression was significantly increased in both the CAPE and CAPE-bevacizumab combination groups compared to the H 2 O 2 group. CAPE has a protective effect on ARPE-19 cells against oxidative stress, and VEGF protein level and expression can be decreased by incubation with different concentrations of CAPE. These results demonstrate that CAPE suppresses the mitochondria-mediated apoptosis in ARPE-19 cells under oxidative stress. In addition, the use of CAPE in combination with bevacizumab has an additive effect.

  17. Kinetic characteristics of polygalacturonase enzymes hydrolyzing galacturonic acid oligomers using isothermal titration calorimetry

    Science.gov (United States)

    Polygalacturonase enzymes hydrolyze the polygalacturonic acid chains found in pectin. Interest in polygalacturonase enzymes continues as they are useful in a number of industrial processes and conversely, detrimental, as they are involved in maceration of economically important crops. While a good...

  18. Reuse of Organomineral Substrate Waste from Hydroponic Systems as Fertilizer in Open-Field Production Increases Yields, Flavonoid Glycosides, and Caffeic Acid Derivatives of Red Oak Leaf Lettuce (Lactuca sativa L.) Much More than Synthetic Fertilizer.

    Science.gov (United States)

    Dannehl, Dennis; Becker, Christine; Suhl, Johanna; Josuttis, Melanie; Schmidt, Uwe

    2016-09-28

    Effects of organic waste from a hydroponic system added with minerals (organomineral fertilizer) and synthetic fertilizer on major polyphenols of red oak leaf lettuce using HPLC-DAD-ESI-MS(3) were investigated. Interestingly, contents of the main flavonoid glycosides and caffeic acid derivatives of lettuce treated with organomineral fertilizer were equal to those synthesized without soil additives. This was found although soil nutrient concentrations, including that of nitrogen, were much lower without additives. However, lettuce treated with synthetic fertilizer showed a significant decrease in contents of caffeic acid derivatives and flavonoid glycosides up to 78.3 and 54.2%, respectively. It is assumed that a negative effect of a high yield on polyphenols as described in the growth-differentiation balance hypothesis can be counteracted by (i) a higher concentration of Mg or (ii) optimal physical properties of the soil structure. Finally, the organomineral substrate waste reused as fertilizer and soil improver resulted in the highest yield (+78.7%), a total fertilizer saving of 322 kg ha(-1) and waste reduction in greenhouses.

  19. From the X-rays to a reliable “low cost” computational structure of caffeic acid: DFT, MP2, HF and integrated molecular dynamics-X-ray diffraction approach to condensed phases

    Science.gov (United States)

    Lombardo, Giuseppe M.; Portalone, Gustavo; Colapietro, Marcello; Rescifina, Antonio; Punzo, Francesco

    2011-05-01

    The ability of caffeic acid to act as antioxidant against hyperoxo-radicals as well as its recently found therapeutic properties in the treatment of hepatocarcinoma, still make this compound, more than 20 years later the refinement of its crystal structure, object of study. It belongs to the vast family of humic substances, which play a key role in the biodegradation processes and easily form complexes with ions widely diffused in the environment. This class of compounds is therefore interesting for potential environmental chemistry applications concerning the possible complexation of heavy metals. Our study focused on the characterization of caffeic acid as a starting necessary step, which will be followed in the future by the application of our findings on the study of the properties of caffeate anion interaction with heavy metal ions. To reach this goal, we applied a low cost approach - in terms of computational time and resources - aimed at the achievement of a high resolution, robust and trustable structure using the X-ray single crystal data, recollected with a higher resolution, as touchstone for a detailed check. A comparison between the calculations carried out with density functional theory (DFT), Hartree-Fock (HF) method and post SCF second order Møller-Plesset perturbation method (MP2), at the 6-31G ** level of the theory, molecular mechanics (MM) and molecular dynamics (MD) was performed. As a consequence we explained on one hand the possible reasons for the pitfalls of the DFT approach and on the other the benefits of using a good and robust force field developed for condensed phases, as AMBER, with MM and MD. The reliability of the latter, highlighted by the overall agreement extended up to the anisotropic displacement parameters calculated by means of MD and the ones gathered by X-ray measurements, makes it very promising for the above-mentioned goals.

  20. Peptide nucleic acid (PNA) cell penetrating peptide (CPP) conjugates as carriers for cellular delivery of antisense oligomers

    DEFF Research Database (Denmark)

    Shiraishi, Takehiko; Nielsen, Peter E

    2012-01-01

    We have explored the merits of a novel delivery strategy for the antisense oligomers based on cell penetrating peptide (CPP) conjugated to a carrier PNA with sequence complementary to part of the antisense oligomer. The effect of these carrier CPP-PNAs was evaluated by using antisense PNA targeting......-PNA (cPNA1(7)-(D-Arg)8) and hexamer carrier decanoyl-CPP-PNA (Deca-cPNA1(6)-(D-Arg)8), respectively, without showing significant additional cellular toxicity. Most interestingly, the activity reached the same level obtained by enhancement with endosomolytic chloroquine (CQ) treatment, suggesting...... that the carrier might facilitate endosomal escape. Furthermore, 50% downregulation of luciferase expression at 60 nM siRNA was obtained using this carrier CPP-PNA delivery strategy (with CQ co-treatment) for a single stranded antisense RNA targeting normal luciferase mRNA. These results indicated that CPP...

  1. Structural Alterations of Lignins in Transgenic Poplars with Depressed Cinnamyl Alcohol Dehydrogenase or Caffeic Acid O-Methyltransferase Activity Have an Opposite Impact on the Efficiency of Industrial Kraft Pulping1

    Science.gov (United States)

    Lapierre, Catherine; Pollet, Brigitte; Petit-Conil, Michel; Toval, Gabriel; Romero, Javier; Pilate, Gilles; Leplé, Jean-Charles; Boerjan, Wout; Ferret, Valérie; De Nadai, Véronique; Jouanin, Lise

    1999-01-01

    We evaluated lignin profiles and pulping performances of 2-year-old transgenic poplar (Populus tremula × Populus alba) lines severely altered in the expression of caffeic acid/5-hydroxyferulic acid O-methyltransferase (COMT) or cinnamyl alcohol dehydrogenase (CAD). Transgenic poplars with CAD or COMT antisense constructs showed growth similar to control trees. CAD down-regulated poplars displayed a red coloration mainly in the outer xylem. A 90% lower COMT activity did not change lignin content but dramatically increased the frequency of guaiacyl units and resistant biphenyl linkages in lignin. This alteration severely lowered the efficiency of kraft pulping. The Klason lignin level of CAD-transformed poplars was slightly lower than that of the control. Whereas CAD down-regulation did not change the frequency of labile ether bonds or guaiacyl units in lignin, it increased the proportion of syringaldehyde and diarylpropane structures and, more importantly with regard to kraft pulping, of free phenolic groups in lignin. In the most depressed line, ASCAD21, a substantially higher content in free phenolic units facilitated lignin solubilization and fragmentation during kraft pulping. These results point the way to genetic modification of lignin structure to improve wood quality for the pulp industry. PMID:9880356

  2. Caffeic Acid Phenethyl Ester (Propolis Extract) Ameliorates Insulin Resistance by Inhibiting JNK and NF-κB Inflammatory Pathways in Diabetic Mice and HepG2 Cell Models.

    Science.gov (United States)

    Nie, Jiarui; Chang, Yaning; Li, Yujia; Zhou, Yingjun; Qin, Jiawen; Sun, Zhen; Li, Haibin

    2017-10-18

    Caffeic acid phenethyl ester (CAPE), extracted from propolis, was evaluated for the ameliorative effects on insulin resistance and the mechanisms were identified, using non-insulin-dependent diabetes mellitus (NIDDM) model mice and insulin resistance (IR) model cells. After 5 weeks of CAPE supplementation, insulin sensitivity, hyperlipidemia, and peroxisome proliferator-activated receptor-α (PPAR-α) levels were improved in mice. Proinflammatory cytokines in serum and the expressions of tumor necrosis factor-alpha (TNF-α) mRNA in tissues were markedly downregulated from CAPE-treated mice. In vitro, CAPE supplement significantly improved glucose consumption, glucose uptake, glycogen content, and oxidative stress and decreased expression of glucose-6-phosphatase (G6Pase) mRNA in cells. Both in vivo and in vitro, CAPE enhanced p-Akt (Ser473) and p-insulin receptor substrate (IRS)-1 (Tyr612), but inhibited p-JNK (Thr183/Tyr185), p-NF-κB p65 (Ser536), and nuclear translocation of p-NF-κB p65 (Ser536). In summary, CAPE can ameliorate insulin resistance through modulation of JNK and NF-κB signaling pathway in mice and HepG2 cells.

  3. Poly(ester amide)s based on (L)-lactic acid oligomers and α-amino acids: influence of the α-amino acid side chain in the poly(ester amide)s properties.

    Science.gov (United States)

    Fonseca, Ana C; Coelho, Jorge F J; Valente, Joana F A; Correia, Tiago R; Correia, Ilídio J; Gil, Maria H; Simões, Pedro N

    2013-01-01

    Novel biodegradable and low cytotoxic poly(ester amide)s (PEAs) based on α-amino acids and (L)-lactic acid (L-LA) oligomers were successfully synthesized by interfacial polymerization. The chemical structure of the new polymers was confirmed by spectroscopic analyses. Further characterization suggests that the α-amino acid plays a critical role on the final properties of the PEA. L-phenylalanine provides PEAs with higher glass transition temperature, whereas glycine enhances the crystallinity. The hydrolytic degradation in PBS (pH = 7.4) at 37 °C also depends on the α-amino acid, being faster for glycine-based PEAs. The cytotoxic profiles using fibroblast human cells indicate that the PEAs did not elicit an acute cytotoxic effect. The strategy presented in this work opens the possibility of synthesizing biodegradable PEAs with low citotoxicity by an easy and fast method. It is worth to mention also that the properties of these materials can be fine-tuned only by changing the α-amino acid.

  4. Caffeic acid phenethylester increases stress resistance and enhances lifespan in Caenorhabditis elegans by modulation of the insulin-like DAF-16 signalling pathway.

    Science.gov (United States)

    Havermann, Susannah; Chovolou, Yvonni; Humpf, Hans-Ulrich; Wätjen, Wim

    2014-01-01

    CAPE is an active constituent of propolis which is widely used in traditional medicine. This hydroxycinnamic acid derivate is a known activator of the redox-active Nrf2 signalling pathway in mammalian cells. We used C. elegans to investigate the effects of this compound on accumulation of reactive oxygen species and the modulation of the pivotal redox-active pathways SKN-1 and DAF-16 (homologues of Nrf2 and FoxO, respectively) in this model organism; these results were compared to the effects in Hct116 human colon carcinoma cells. CAPE exerts a strong antioxidative effect in C. elegans: The increase of reactive oxygen species induced by thermal stress was diminished by about 50%. CAPE caused a nuclear translocation of DAF-16, but not SKN-1. CAPE increased stress resistance of the nematode against thermal stress and finally a prolongation of the median and maximum lifespan by 9 and 17%, respectively. This increase in stress resistance and lifespan was dependent on DAF-16 as shown in experiments using a DAF-16 loss of function mutant strain. Life prolongation was retained under SKN-1 RNAi conditions showing that the effect is SKN-1 independent. The results of CAPE obtained in C. elegans differed from the results obtained in Hct116 colon carcinoma cells: CAPE also caused strong antioxidative effects in the mammalian cells, but no activation of the FoxO4 signalling pathway was detectable. Instead, an activation of the Nrf2 signalling pathway was shown by luciferase assay and western blots. CAPE activates the insulin-like DAF-16, but not the SKN-1 signalling pathway in C. elegans and therefore enhances the stress resistance and lifespan of this organism. Since modulation of the DAF-16 pathway was found to be a pivotal effect of CAPE in C. elegans, this has to be taken into account for the investigation of the molecular mechanisms of the traditional use of propolis.

  5. Human proton coupled folic acid transporter is a monodisperse oligomer in the lauryl maltose neopentyl glycol solubilized state

    DEFF Research Database (Denmark)

    Aduri, Nanda G.; Ernst, Heidi A.; Prabhala, Bala K.

    2018-01-01

    and purification of recombinant PCFT. Following detergent screening n-Dodecyl β-D-maltoside (DDM) and lauryl maltose neopentyl glycol (LMNG) were chosen for further work as they exhibited the most optimal solubilization. We found that purified detergent solubilized PCFT was able to bind folic acid, thus indicating...

  6. Improved fluorescent labeling of chitin oligomers: Chitinolytic properties of acidic mammalian chitinase under somatic tissue pH conditions.

    Science.gov (United States)

    Wakita, Satoshi; Kimura, Masahiro; Kato, Naoki; Kashimura, Akinori; Kobayashi, Shunsuke; Kanayama, Naoto; Ohno, Misa; Honda, Shotaro; Sakaguchi, Masayoshi; Sugahara, Yasusato; Bauer, Peter O; Oyama, Fumitaka

    2017-05-15

    Acidic mammalian chitinase (AMCase) has been implicated in various pathophysiological conditions including asthma, allergic inflammation and food processing. AMCase is most active at pH 2.0, and its activity gradually decreases to up to pH 8. Here we analyzed chitin degradation by AMCase in weak acidic to neutral conditions by fluorophore-assisted carbohydrate electrophoresis established originally for oligosaccharides analysis. We found that specific fragments with slower-than-expected mobility as defined by chitin oligosaccharide markers were generated at pH 5.0∼8.0 as by-products of the reaction. We established an improved method for chitin oligosaccharides suppressing this side reaction by pre-acidification of the fluorophore-labeling reaction mixture. Our improved method specifically detects chitin oligosaccharides and warrants quantification of up to 50nmol of the material. Using this strategy, we found that AMCase produced dimer of N-acetyl-d-glucosamine (GlcNAc) at strong acidic to neutral condition. Moreover, we found that AMCase generates (GlcNAc) 2 as well as (GlcNAc) 3 under physiological conditions. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  7. Characteristics of tau oligomers

    Directory of Open Access Journals (Sweden)

    Yan eRen

    2013-07-01

    Full Text Available In Alzheimer disease (AD and other tauopathies, microtubule-associated protein tau becomes hyperphosphorylated, undergoes conformational changes, aggregates, eventually becoming neurofibrillary tangles (NFTs. As accumulating evidence suggests that NFTs themselves may not be toxic, attention is now turning toward the role of intermediate tau oligomers in AD pathophysiology. Sarkosyl extraction is a standard protocol for investigating insoluble tau aggregates in brains. There is a growing consensus that sarkosyl-insoluble tau correlates with the pathological features of tauopathy. While sarkosyl-insoluble tau from tauopathy brains has been well characterized as a pool of filamentous tau, other dimers, multimers, and granules of tau are much less well understood. There are protocols for identifying these tau oligomers. In this mini review, we discuss the characteristics of tau oligomers isolated via different methods and materials.

  8. Radiation curable oligomers

    International Nuclear Information System (INIS)

    Huemmer, T.F.; Edison, B.A.

    1977-01-01

    A process is described for the high energy radiation curing of oligomers for use as coatings. The method is particularly applicable to the reaction products of certain low molecular weight epoxy compounds and certain low molecular weight mono-hydroxy vinyl compounds having at least one vinylic unsaturation. The curable mixture is applied as a thin film and cured very quickly

  9. Electrorheology of aniline oligomers

    Czech Academy of Sciences Publication Activity Database

    Mrlík, M.; Sedlačík, M.; Pavlínek, V.; Bober, Patrycja; Trchová, Miroslava; Stejskal, Jaroslav; Sáha, P.

    2013-01-01

    Roč. 291, č. 9 (2013), s. 2079-2086 ISSN 0303-402X R&D Projects: GA ČR GA202/09/1626 Institutional support: RVO:61389013 Keywords : anilin e oligomers * polyaniline * electrorheology Subject RIV: JI - Composite Materials Impact factor: 2.410, year: 2013

  10. Preparation of Stable Amyloid-β Oligomers Without Perturbative Methods.

    Science.gov (United States)

    Kotler, Samuel A; Ramamoorthy, Ayyalusamy

    2018-01-01

    Soluble amyloid-β (Aβ) oligomers have become a focal point in the study of Alzheimer's disease due to their ability to elicit cytotoxicity. A number of recent studies have concentrated on the structural characterization of soluble Aβ oligomers to gain insight into their mechanism of toxicity. Consequently, providing reproducible protocols for the preparation of such oligomers is of utmost importance. The method presented in this chapter details a protocol for preparing an Aβ oligomer, with a primarily disordered secondary structure, without the need for chemical modification or amino acid substitution. Due to the stability of these disordered Aβ oligomers and the reproducibility with which they form, they are amenable for biophysical and high-resolution structural characterization.

  11. Aniline oligomers versus polyaniline

    Czech Academy of Sciences Publication Activity Database

    Stejskal, Jaroslav; Trchová, Miroslava

    2012-01-01

    Roč. 61, č. 2 (2012), s. 240-251 ISSN 0959-8103 R&D Projects: GA AV ČR IAA400500905; GA AV ČR IAA100500902; GA ČR GA203/08/0686; GA ČR GA202/09/1626 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyaniline * anilin e oligomers * anilin e Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.125, year: 2012

  12. PIPERIDINE OLIGOMERS AND COMBINATORIAL LIBRARIES THEREOF

    DEFF Research Database (Denmark)

    1999-01-01

    The present invention relates to piperidine oligomers, methods for the preparation of piperidine oligomers and compound libraries thereof, and the use of piperidine oligomers as drug substances. The present invention also relates to the use of combinatorial libraries of piperidine oligomers...... in libraries (arrays) of compounds especially suitable for screening purposes....

  13. Clicked Cinnamic/Caffeic Esters and Amides as Radical Scavengers and 5-Lipoxygenase Inhibitors

    Directory of Open Access Journals (Sweden)

    Jérémie A. Doiron

    2014-01-01

    Full Text Available 5-Lipoxygenase (5-LO is the key enzyme responsible for the conversion of arachidonic acid to leukotrienes, a class of lipid mediators implicated in inflammatory disorders. In this paper, we describe the design, synthesis, and preliminary activity studies of novel clicked caffeic esters and amides as radical scavengers and 5-LO inhibitors. From known 5-LO inhibitor 3 as a lead, cinnamic esters 8a–h and amides 9a–h as well as caffeic esters 15a–h and amides 16a–h were synthesized by Cu(I-catalyzed [1,3]-dipolar cycloaddition with the appropriate azide precursors and terminal alkynes. All caffeic analogs are proved to be good radical scavengers (IC50: 10–20 μM. Esters 15g and 15f possessed excellent 5-LO inhibition activity in HEK293 cells and were equipotent with the known 5-LO inhibitor CAPE and more potent than Zileuton. Several synthesized esters possess activities rivaling Zileuton in stimulated human polymorphonuclear leukocytes.

  14. Preparation of Chito-Oligomers by Hydrolysis of Chitosan in the Presence of Zeolite as Adsorbent

    Science.gov (United States)

    Ibrahim, Khalid A.; El-Eswed, Bassam I.; Abu-Sbeih, Khaleel A.; Arafat, Tawfeeq A.; Al Omari, Mahmoud M. H.; Darras, Fouad H.; Badwan, Adnan A.

    2016-01-01

    An increasing interest has recently been shown to use chitin/chitosan oligomers (chito-oligomers) in medicine and food fields because they are not only water-soluble, nontoxic, and biocompatible materials, but they also exhibit numerous biological properties, including antibacterial, antifungal, and antitumor activities, as well as immuno-enhancing effects on animals. Conventional depolymerization methods of chitosan to chito-oligomers are either chemical by acid-hydrolysis under harsh conditions or by enzymatic degradation. In this work, hydrolysis of chitosan to chito-oligomers has been achieved by applying adsorption-separation technique using diluted HCl in the presence of different types of zeolite as adsorbents. The chito-oligomers were retrieved from adsorbents and characterized by differential scanning calorimetry (DSC), liquid chromatography/mass spectroscopy (LC/MS), and ninhydrin test. PMID:27455287

  15. Preparation of Chito-Oligomers by Hydrolysis of Chitosan in the Presence of Zeolite as Adsorbent

    Directory of Open Access Journals (Sweden)

    Khalid A. Ibrahim

    2016-07-01

    Full Text Available An increasing interest has recently been shown to use chitin/chitosan oligomers (chito-oligomers in medicine and food fields because they are not only water-soluble, nontoxic, and biocompatible materials, but they also exhibit numerous biological properties, including antibacterial, antifungal, and antitumor activities, as well as immuno-enhancing effects on animals. Conventional depolymerization methods of chitosan to chito-oligomers are either chemical by acid-hydrolysis under harsh conditions or by enzymatic degradation. In this work, hydrolysis of chitosan to chito-oligomers has been achieved by applying adsorption-separation technique using diluted HCl in the presence of different types of zeolite as adsorbents. The chito-oligomers were retrieved from adsorbents and characterized by differential scanning calorimetry (DSC, liquid chromatography/mass spectroscopy (LC/MS, and ninhydrin test.

  16. Design, synthesis, and characterization of biomimetic oligomers

    DEFF Research Database (Denmark)

    Laursen, Jonas Striegler

    a helical arrangement found by DFT calculations. The designed oligomer indeed proved the existence of a ß-peptoid helical conformation by X-ray. Further studies of these compounds indicated a structured display in solution. These helices thus definitively show that the ß-peptoids should be considered......Peptides and proteins made from the 20 canonical amino acids are responsible for many processes necessary for organisms to function. Beside their composition, proteins obtain their activity and unique selectivity through an ability to display functionalities accurately in the three......, for their ability to mimic the structural elements seen in proteins. Two prominent peptidomimetics are ß-peptides and a-peptoids (N-alkylglycines), which have been shown to fold into helical and sheet-like arrangements. To expand the chemical space available for mimicking protein structure their features have been...

  17. Simultaneous determination of chlorogenic acid, caffeic acid and caffeine in hydroalcoholic and aqueous extracts of Ilex paraguariensis by HPLC and correlation with antioxidant capacity of the extracts by DPPH· reduction Determinação simultânea de ácido clorogênico, ácido caféico e cafeína, no extrato aquoso e hidroalcoólico de Ilex paraguariensis por CLAE e correlação com a capacidade antioxidante dos extratos por redução do DPPH·

    Directory of Open Access Journals (Sweden)

    Diogo Pineda Rivelli

    2007-06-01

    Full Text Available A new high performance liquid chromatographic method has been established for simultaneous determination of chlorogenic acid, caffeic acid and caffeine in hydroalcoholic and aqueous extracts of Ilex paraguariensis. Analytical curves showed good linear regression in the concentration ranges 0.49-7.8 µg/mL for chlorogenic acid, 0.25-3.9 µg/mL for caffeic acid and 0.244-7.8 µg/mL for caffeine. Reduction of the DPPH· radical was used to determine the antioxidant capacity of the extracts. Our method for the simultaneous determination of chlorogenic acid, caffeic acid and caffeine was highly sensitive, having lower detection and quantitation limits than other papers that used similar methodology.Um novo método de cromatografia líquida de alta eficiência foi desenvolvido para a determinação simultânea de ácido clorogênico, ácido caféico e cafeína no extrato hidroalcoólico e aquoso de Ilex paraguariensis. As curvas de calibração mostraram boa regressão linear nas faixas de concentração 0,49-7,8 µg/mL para o ácido clorogênico, 0,25-3,9 µg/mL para ácido caféico e 0,244-7,8 µg/mL para cafeína. A redução do radical DPPH· foi usada para determinar a capacidade antioxidante dos extratos. Nosso método para a determinação simultânea de ácido caféico, ácido clorogênico e cafeína foi altamente sensível, possuindo limites de detecção e de quantificação menores do que em outros trabalhos que empregaram metodologias semelhantes.

  18. Determination of oligomers in virgin and recycled polyethylene terephthalate (PET) samples by UPLC-MS-QTOF.

    Science.gov (United States)

    Ubeda, Sara; Aznar, Margarita; Nerín, Cristina

    2018-03-01

    An oligomer is a molecule that consists of a few monomer units. It can be formed during polymer manufacturing and also due to polymer degradation processes or even during use conditions. Since oligomers are not included in chemical databases, their identification is a complex process. In this work, the oligomers present in 20 different PET pellet samples have been determined. Two different sample treatment procedures, solvent extraction and total dissolution, were applied in order to select the most efficient one. The analyses were carried out by UPLC-MS-QTOF. The use of high resolution mass spectrometry allowed the structural elucidation of these compounds and their correct identification. The main oligomers identified were cyclic as well as lineal from the first, second, and third series. All of them were composed of terephthalic acid (TPA), diethylene glycol (DEG), and ethylene glycol (EG). Quantitative values were very different in both procedures. In total dissolution of PET samples, the concentration of oligomers was always, at least, 10 times higher than in solvent extraction; some of the compounds were only detected when total dissolution was used. Results showed that the oligomers with the highest concentration values were dimers and trimers, cyclic, as well as lineal, from the first and second series. The oligomer with the maximum concentration value was TPA 2 -EG-DEG that was found in all the samples in a concentration range from 2493 to 19,290 ng/g PET. No differences between virgin and recycled PET were found. Migration experiments were performed in two PET bottles, and results showed the transference of most of these oligomers to a fat food simulant (ethanol 95%). Graphical abstract Graphical abstract of the two procedures developd and optimized for identifying oligomers in PET pellets and in migration form PET bottles.

  19. Targeting α-synuclein oligomers

    DEFF Research Database (Denmark)

    van Diggelen, Femke

    Parkinson’s Disease (PD) is a complex disease, characterised by degeneration of neocortical, limbic and nigrostriatal neurons. It is unknown what initiates neurodegeneration, but soluble oligomers of the protein α-synuclein (αSn) seem to be particularly toxic, compared to insoluble fibrils...... unique characteristics, e.g. they were recognized by different conformational antibodies and DHA–αSOs also formed a second elongated species in addition to the dominant spherical species. Although further functional testing is needed, this suggests that each species has its own distinct toxic mechanism......+/K+ ATPase, V-type ATPase, VDAC, CaMKII and Rab-3A. The identification of these targets is a first step towards unravelling the toxic pathways which are activated upon synaptic binding of extracellularly added αSOs, and hopefully will contribute to the discovery of new disease modifying compounds, which can...

  20. A Fluorescent Assay for Plant Caffeic Acid O-methyltransferases

    Science.gov (United States)

    We have developed a facile, sensitive and continuous assay to measure the activities of plant COMTs using s-adenosyl homocysteine hydrolase as a coupling enzyme and and adeonsine a thiol-specific fluor, Thioglo1, as the detecting reagent. This assay was validated using recombinant sorghum COMT (BMR-...

  1. Caffeic Acid Phenethyl Ester (CAPE) mediated decrease in ...

    African Journals Online (AJOL)

    ... is a phytochemically active component obtained from honeybee hive propolis. ... We hypothesize the effect of CAPE on the metastasis of colon cancer cells in ... evaluated also expression of protein and matrix metalloproteinases (MMPs) ...

  2. Boron-rich oligomers for BNCT

    International Nuclear Information System (INIS)

    Gula, M.; Perleberg, O.; Gabel, D.

    2000-01-01

    The synthesis of two BSH derivatives is described, which can be used for oligomerization in DNA-synthesizers. Synthesis pathways lead to final products in five and six steps, respectively. Because of chirality interesting results were expected. NMR-measurements confirm this expectation. Possible oligomers with high concentrations of boron can be attached to biomolecules. These oligomers can be explored with several imaging methods (EELS, PEM) to determine the lower detection limit of boron with these methods. (author)

  3. Electron beam curing of acrylic oligomers

    International Nuclear Information System (INIS)

    Seto, J.; Arakawa, S.; Ishimoto, C.; Miyashita, M.; Nagai, T.; Noguchi, T.; Shibata, A.

    1984-01-01

    The electron-beam curing process of acrylic oligomers, with and without γ-Fe 2 O 3 pigment filler and blended linear polymer, was investigated in terms of molecular structure and reaction mechanism. The polymerized fraction of trimethylolpropane-triacrylate (TMPTA) oligomers increases with increasing total dose, and is independent of the dose rate. Since the reaction rate is linearly dependent on the dose rate, the reaction mechanism involves monomolecular termination. The reaction rate does not depend on the number of functional groups of the oligomer at low doses, but above 0.3 Mrad the rate is slower for oligomers of higher functionality. A gel is formed more readily upon curing of a polyfunctional than a monofunctional oligomer, especially at high conversion to polymer; the resulting loss of flexibility of the polymer chains slows the reaction. Decrease of the molecular weight per functional group results in lower conversion; this is also due to the loss of chain flexibility, which is indicated as well by a higher glass-transition temperature. Modification of the acrylate oligomers with urethane results in more effective cross-linking reactions because of the more rigid molecular chains. Addition of γ-Fe 2 O 3 pigment reduces the reaction rate very little, but has the effect of providing added structural integrity, as indicated by the decrease of solvent-extractable material and the improvement of anti-abrasion properties. However, the flexibility of the coating and its adhesion to a PET base film are diminished. To increase the flexibility, linear polyvinylchloride and/or polyurethane were added to the acrylic oligomers. Final conversion to polymer was nearly 100 percent, and a higher elastic modulus and better antiabrasion properties were realized

  4. Analysis of linear and cyclic oligomers in polyamide-6 without sample preparation by liquid chromatography using the sandwich injection method. II. Methods of detection and quantification and overall long-term performance.

    Science.gov (United States)

    Mengerink, Y; Peters, R; Kerkhoff, M; Hellenbrand, J; Omloo, H; Andrien, J; Vestjens, M; van der Wal, S

    2000-05-05

    By separating the first six linear and cyclic oligomers of polyamide-6 on a reversed-phase high-performance liquid chromatographic system after sandwich injection, quantitative determination of these oligomers becomes feasible. Low-wavelength UV detection of the different oligomers and selective post-column reaction detection of the linear oligomers with o-phthalic dicarboxaldehyde (OPA) and 3-mercaptopropionic acid (3-MPA) are discussed. A general methodology for quantification of oligomers in polymers was developed. It is demonstrated that the empirically determined group-equivalent absorption coefficients and quench factors are a convenient way of quantifying linear and cyclic oligomers of nylon-6. The overall long-term performance of the method was studied by monitoring a reference sample and the calibration factors of the linear and cyclic oligomers.

  5. Self-propagative replication of Aβ oligomers suggests potential transmissibility in Alzheimer disease.

    Directory of Open Access Journals (Sweden)

    Amit Kumar

    Full Text Available The aggregation of amyloid-β (Aβ peptide and its deposition in parts of the brain form the central processes in the etiology of Alzheimer disease (AD. The low-molecular weight oligomers of Aβ aggregates (2 to 30 mers are known to be the primary neurotoxic agents whose mechanisms of cellular toxicity and synaptic dysfunction have received substantial attention in the recent years. However, how these toxic agents proliferate and induce widespread amyloid deposition throughout the brain, and what mechanism is involved in the amplification and propagation of toxic oligomer species, are far from clear. Emerging evidence based on transgenic mice models indicates a transmissible nature of Aβ aggregates and implicates a prion-like mechanism of oligomer propagation, which manifests as the dissemination and proliferation of Aβ toxicity. Despite accumulating evidence in support of a transmissible nature of Aβ aggregates, a clear, molecular-level understanding of this intriguing mechanism is lacking. Recently, we reported the characterization of unique replicating oligomers of Aβ42 (12-24 mers in vitro called Large Fatty Acid-derived Oligomers (LFAOs (Kumar et al., 2012, J. Biol. Chem. In the current report, we establish that LFAOs possess physiological activity by activating NF-κB in human neuroblastoma cells, and determine the experimental parameters that control the efficiency of LFAO replication by self-propagation. These findings constitute the first detailed report on monomer - oligomer lateral propagation reactions that may constitute potential mechanism governing transmissibility among Aβ oligomers. These data support the previous reports on transmissible mechanisms observed in transgenic animal models.

  6. Applications of oligomers for nanostructured conducting polymers.

    Science.gov (United States)

    Wang, Yue; Tran, Henry D; Kaner, Richard B

    2011-01-03

    This Feature Article provides an overview of the distinctive nanostructures that aniline oligomers form and the applications of these oligomers for shaping the nanoscale morphologies and chirality of conducting polymers. We focus on the synthetic methods for achieving such goals and highlight the underlying mechanisms. The clear advantages of each method and their possible drawbacks are discussed. Assembly and applications of these novel organic (semi)conducting nanomaterials are also outlined. We conclude this article with our perspective on the main challenges, new opportunities, and future directions for this nascent yet vibrant field of research. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Formation of nitrogen-containing oligomers by methylglyoxal and amines in simulated evaporating cloud droplets.

    Science.gov (United States)

    De Haan, David O; Hawkins, Lelia N; Kononenko, Julia A; Turley, Jacob J; Corrigan, Ashley L; Tolbert, Margaret A; Jimenez, Jose L

    2011-02-01

    Reactions of methylglyoxal with amino acids, methylamine, and ammonium sulfate can take place in aqueous aerosol and evaporating cloud droplets. These processes are simulated by drying droplets and bulk solutions of these compounds (at low millimolar and 1 M concentrations, respectively) and analyzing the residuals by scanning mobility particle sizing, nuclear magnetic resonance, aerosol mass spectrometry (AMS), and electrospray ionization MS. The results are consistent with imine (but not diimine) formation on a time scale of seconds, followed by the formation of nitrogen-containing oligomers, methylimidazole, and dimethylimidazole products on a time scale of minutes to hours. Measured elemental ratios are consistent with imidazoles and oligomers being major reaction products, while effective aerosol densities suggest extensive reactions take place within minutes. These reactions may be a source of the light-absorbing, nitrogen-containing oligomers observed in urban and biomass-burning aerosol particles.

  8. Combined HILIC-ELSD/ESI-MS(n) enables the separation, identification and quantification of sugar beet pectin derived oligomers.

    Science.gov (United States)

    Remoroza, C; Cord-Landwehr, S; Leijdekkers, A G M; Moerschbacher, B M; Schols, H A; Gruppen, H

    2012-09-01

    The combined action of endo-polygalacturonase (endo-PGII), pectin lyase (PL), pectin methyl esterase (fungal PME) and RG-I degrading enzymes enabled the extended degradation of methylesterified and acetylated sugar beet pectins (SBPs). The released oligomers were separated, identified and quantified using hydrophilic interaction liquid chromatography (HILIC) with online electrospray ionization ion trap mass spectrometry (ESI-IT-MS(n)) and evaporative light scattering detection (ELSD). By MS(n), the structures of galacturonic acid (GalA) oligomers having an acetyl group in the O-2 and/or O-3 positions eluting from the HILIC column were elucidated. The presence of methylesterified and/or acetylated galacturonic acid units within an oligomer reduced the interaction with the HILIC column significantly compared to the unsubstituted GalA oligomers. The HILIC column enables a good separation of most oligomers present in the digest. The use of ELSD to quantify oligogalacturonides was validated using pure GalA standards and the signal was found to be independent of the chemical structure of the oligomer being detected. The combination of chromatographic and enzymatic strategies enables to distinguish SBPs having different methylesters and acetyl group distribution. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Electrografting of conductive oligomers and polymers using diazonium electroreduction

    International Nuclear Information System (INIS)

    Lacroix, Jean Christophe; Trippe-Allard, Gaelle; Ghilane, Jalal; Martin, Pascal

    2014-01-01

    This paper describes the attachment of conjugated oligomers onto electrode surface through the reduction of diazonium compounds. In this connection some properties of conjugated oligomers and of layers grafted through diazonium electroreduction will first be briefly presented. The electrochemical behavior of conjugated oligomers grafted on a surface using diazonium electroreduction will then be discussed. (paper)

  10. Electrografting of conductive oligomers and polymers using diazonium electroreduction

    Science.gov (United States)

    Lacroix, Jean Christophe; Trippe-Allard, Gaelle; Ghilane, Jalal; Martin, Pascal

    2014-03-01

    This paper describes the attachment of conjugated oligomers onto electrode surface through the reduction of diazonium compounds. In this connection some properties of conjugated oligomers and of layers grafted through diazonium electroreduction will first be briefly presented. The electrochemical behavior of conjugated oligomers grafted on a surface using diazonium electroreduction will then be discussed.

  11. Synthesis and characterization of thermally stable oligomer-metal ...

    African Journals Online (AJOL)

    The thermal stabilities of the oligomer-metal complexes were compared by thermogravimetric (TG) and differential thermal (DTA) analyses. According to TG, oligomer-metal complexes were stable against to temperature and thermooxidative decomposition. The weight losses of oligomer-metal complexes were found to be 5 ...

  12. Peptide oligomers for holographic data storage

    DEFF Research Database (Denmark)

    Berg, Rolf Henrik; Hvilsted, Søren; Ramanujam, P.S.

    1996-01-01

    SEVERAL classes of organic materials (such as photoanisotropic liquid-crystalline polymers(1-4) and photorefractive polymers(5-7)) are being investigated for the development of media for optical data storage. Here we describe a new family of organic materials-peptide oligomers containing azobenzene...

  13. Electrochemical behavior of antioxidants: Part 3. Electrochemical studies of caffeic Acid–DNA interaction and DNA/carbon nanotube biosensor for DNA damage and protection

    Directory of Open Access Journals (Sweden)

    Refat Abdel-Hamid

    2016-05-01

    Full Text Available Multi-walled carbon nanotubes-modified glassy carbon electrode biosensor was used for electrochemical studies of caffeic acid–dsDNA interaction in phosphate buffer solution at pH 2.12. Caffeic acid, CAF, shows a well-defined cyclic voltammetric wave. Its anodic peak current decreases and the peak potential shifts positively on the addition of dsDNA. This behavior was ascribed to an interaction of CAF with dsDNA giving CAF–dsDNA complex by intercalative binding mode. The apparent binding constant of CAF–dsDNA complex was determined using amperometric titrations. The oxidative damage caused to DNA was detected using the biosensor. The damage caused by the reactive oxygen species, hydroxyl radical (·−OH generated by the Fenton system on the DNA-biosensor was detected. It was found that CAF has the capability of scavenging the hydroxide radical and protecting the DNA immobilized on the GCE surface.

  14. Supersymmetry theory of microphase separation in homopolymer-oligomer mixtures

    International Nuclear Information System (INIS)

    Olemskoi, Alexander; Krakovsky, Ivan; Savelyev, Alexey

    2004-01-01

    The mesoscopic structure of periodically alternating layers of stretched homopolymer chains surrounded by perpendicularly oriented oligomeric tails is studied for systems with both strong (ionic) and weak (hydrogen) interactions. We focus on the consideration of the distribution of oligomers along the homopolymer chains that is described by the effective equation of motion with the segment number playing the role of imaginary time. The supersymmetry technique is developed to consider associative hydrogen bonding, self-action effects, inhomogeneity, and temperature fluctuations in the oligomer distribution. Making use of the self-consistent approach allows one to explain experimentally observed temperature dependence of the structure period and the order-disorder transition temperature and period as functions of the oligomeric fraction for systems with different bonding strengths. A whole set of parameters of the model used is found for strong, intermediate, and weak coupled systems being Poly (4-vinyl pyridine)-dodecyl benzene sulfonic acid [P4VP-(DBSA) x ], P4VP-[Zn(DBS) 2 ] x , and P4VP- 3-pentadecyl Phenol x , respectively. A passage from the former two to the latter is shown to cause a crucial decrease in the magnitude of both parameters of hydrogen bonding and self-action, as well as the order-disorder transition temperature

  15. Dual Myostatin and Dystrophin Exon Skipping by Morpholino Nucleic Acid Oligomers Conjugated to a Cell-penetrating Peptide Is a Promising Therapeutic Strategy for the Treatment of Duchenne Muscular Dystrophy

    Directory of Open Access Journals (Sweden)

    Alberto Malerba

    2012-01-01

    Full Text Available The knockdown of myostatin, a negative regulator of skeletal muscle mass may have important implications in disease conditions accompanied by muscle mass loss like cancer, HIV/AIDS, sarcopenia, muscle atrophy, and Duchenne muscular dystrophy (DMD. In DMD patients, where major muscle loss has occurred due to a lack of dystrophin, the therapeutic restoration of dystrophin expression alone in older patients may not be sufficient to restore the functionality of the muscles. We recently demonstrated that phosphorodiamidate morpholino oligomers (PMOs can be used to re-direct myostatin splicing and promote the expression of an out-of-frame transcript so reducing the amount of the synthesized myostatin protein. Furthermore, the systemic administration of the same PMO conjugated to an octaguanidine moiety (Vivo-PMO led to a significant increase in the mass of soleus muscle of treated mice. Here, we have further optimized the use of Vivo-PMO in normal mice and also tested the efficacy of the same PMO conjugated to an arginine-rich cell-penetrating peptide (B-PMO. Similar experiments conducted in mdx dystrophic mice showed that B-PMO targeting myostatin is able to significantly increase the tibialis anterior (TA muscle weight and when coadministered with a B-PMO targeting the dystrophin exon 23, it does not have a detrimental interaction. This study confirms that myostatin knockdown by exon skipping is a potential therapeutic strategy to counteract muscle wasting conditions and dual myostatin and dystrophin skipping has potential as a therapy for DMD.

  16. Nitrogen-Containing, Light-Absorbing Oligomers Produced in Aerosol Particles Exposed to Methylglyoxal, Photolysis, and Cloud Cycling.

    Science.gov (United States)

    De Haan, David O; Tapavicza, Enrico; Riva, Matthieu; Cui, Tianqu; Surratt, Jason D; Smith, Adam C; Jordan, Mary-Caitlin; Nilakantan, Shiva; Almodovar, Marisol; Stewart, Tiffany N; de Loera, Alexia; De Haan, Audrey C; Cazaunau, Mathieu; Gratien, Aline; Pangui, Edouard; Doussin, Jean-François

    2018-04-03

    Aqueous methylglyoxal chemistry has often been implicated as an important source of oligomers in atmospheric aerosol. Here we report on chemical analysis of brown carbon aerosol particles collected from cloud cycling/photolysis chamber experiments, where gaseous methylglyoxal and methylamine interacted with glycine, ammonium, or methylammonium sulfate seed particles. Eighteen N-containing oligomers were identified in the particulate phase by liquid chromatography/diode array detection/electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry. Chemical formulas were determined and, for 6 major oligomer products, MS 2 fragmentation spectra were used to propose tentative structures and mechanisms. Electronic absorption spectra were calculated for six tentative product structures by an ab initio second order algebraic-diagrammatic-construction/density functional theory approach. For five structures, matching calculated and measured absorption spectra suggest that they are dominant light-absorbing species at their chromatographic retention times. Detected oligomers incorporated methylglyoxal and amines, as expected, but also pyruvic acid, hydroxyacetone, and significant quantities of acetaldehyde. The finding that ∼80% (by mass) of detected oligomers contained acetaldehyde, a methylglyoxal photolysis product, suggests that daytime methylglyoxal oligomer formation is dominated by radical addition mechanisms involving CH 3 CO*. These mechanisms are evidently responsible for enhanced browning observed during photolytic cloud events.

  17. Synthesis of Citric-Acrylate Oligomer and its in-Situ Reaction with Chrome Tanned Collagen (hide powder)

    International Nuclear Information System (INIS)

    Haroun, A.A.; Masoud, R.A.; Bronco, S.; Ciardelli, F.

    2005-01-01

    The purpose of this study was to formulate the new combined system of acrylic and citric acids, which has been prepared by free radical polymerization and esterification reaction at the same time to form citric acrylate (CAC) oligomer through ester linkage and low molecular weight (Mw 2241), in compared with polyacrylic acid. The chemical structure and the reaction mechanism of this oligomer were confirmed by different spectroscopic tools (1 H , 13 C-NMR, ATR-IR), gel permeation chromatography and thermogravimetric analysis (TGA/DTA). The problem of the effect of the masking agents in the chrome tanning of the collagen and the pickling of the hide has been approached from the study of the hydrothermal and mechanical properties, using this new eco-friendly oligomer, which was carried out in-situ treated/grafted chrome tanned collagen (hide powder), and pickled hide. The microemulsion grafting copolymerization of (CAC) using 2.2-azo-bis isobutyronitrile (ABIN), via direct coupling reaction, onto the chrome tanned collagen showed that the free amino groups of the collagen were considered to be a potential site for the in-situ reaction with (CAC) oligomer. Also, using of citric-acrylate (CAC) oligomer, during chrome tanning of leather, instead of the traditional strong acids (sulfuric, hydrochloric and formic) resulted in significant improvement in chrome exhaustion and physical properties

  18. Tau Oligomers as Pathogenic Seeds: Preparation and Propagation In Vitro and In Vivo.

    Science.gov (United States)

    Gerson, Julia E; Sengupta, Urmi; Kayed, Rakez

    2017-01-01

    Tau oligomers have been shown to be the main toxic tau species in a number of neurodegenerative disorders. In order to study tau oligomers both in vitro and in vivo, we have established methods for the reliable preparation, isolation, and detection of tau oligomers. Methods for the seeding of tau oligomers, isolation of tau oligomers from tissue, and detection of tau oligomers using tau oligomer-specific antibodies by biochemical and immunohistochemical methods are detailed below.

  19. Self-assembly of aniline oligomers

    Czech Academy of Sciences Publication Activity Database

    Zhao, Y.; Tomšík, Elena; Wang, J.; Morávková, Zuzana; Zhigunov, Alexander; Stejskal, Jaroslav; Trchová, Miroslava

    2013-01-01

    Roč. 8, č. 1 (2013), s. 129-137 ISSN 1861-4728 R&D Projects: GA ČR GA202/09/1626; GA ČR GAP205/12/0911 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : morphology * oligoaniline * oligomers Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.935, year: 2013

  20. Photopolymerizable silicone monomers, oligomers, and resins

    International Nuclear Information System (INIS)

    Jacobine, A.F.; Nakos, S.T.

    1992-01-01

    The purpose of this chapter is to acquaint the general photopolymer researcher with the historical development of the chemistry and technology of photopolymerizable silicone monomers, fluids, and resins. The current status of research in these areas is assessed. The focus of this chapter is not only on the polymer chemistry and application of this technology, but also on important aspects of the synthetic chemistry involved in the preparation of UV-curable silicone monomers, oligomers, and resins. 236 refs., 6 tabs

  1. Theory of microphase separation in homopolymer-oligomer mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Olemskoi, Alexander [Department of Physical Electronics, Sumy State University, Rimskii-Korsakov St. 2, 40007 Sumy (Ukraine)]. E-mail: alex@ufn.ru; Savelyev, Alexey [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290 (United States)]. E-mail: alexsav@unc.edu

    2005-11-01

    ) interactions. We focus on the consideration of the oligomer distribution along the homopolymer chains that is described by the effective equation of motion with the segment number playing the role of imaginary time. In so doing, we eliminate the Flory-Huggins interactions from explicit consideration showing that at strong tendency for polymer/oligomer segregation not Flory parameter but the strength of non-bonding interactions determines the MS transition to lamellar mesophase. The supersymmetry technique is developed to consider associative hydrogen bonding, self-action (nonlinearity) effects, non-homogeneity and temperature fluctuations in the oligomer distribution. Making use of the self-consistent approach allows one to determine experimentally observed temperature dependence of the structure period and the order-disorder transition temperature for different oligomeric fraction in systems with different bonding strength. A whole set of parameters of the model used is found for strong, intermediate, and weak coupled systems being poly(4-vinyl pyridine)-dodecyl benzene sulfonic acid [P4VP-(DBSA){sub x}], P4VP-[Zn(DBS){sub 2}]{sub x}, and P4VP-3-pentadecyl phenol{sub x}[P4VP-(PDP){sub x}], respectively. A passage from the former two to the latter is shown to cause a crucial decrease in the magnitude of both parameters of hydrogen bonding and self-action, as well as the order-disorder transition temperature.

  2. Theory of microphase separation in homopolymer-oligomer mixtures

    International Nuclear Information System (INIS)

    Olemskoi, Alexander; Savelyev, Alexey

    2005-01-01

    ) interactions. We focus on the consideration of the oligomer distribution along the homopolymer chains that is described by the effective equation of motion with the segment number playing the role of imaginary time. In so doing, we eliminate the Flory-Huggins interactions from explicit consideration showing that at strong tendency for polymer/oligomer segregation not Flory parameter but the strength of non-bonding interactions determines the MS transition to lamellar mesophase. The supersymmetry technique is developed to consider associative hydrogen bonding, self-action (nonlinearity) effects, non-homogeneity and temperature fluctuations in the oligomer distribution. Making use of the self-consistent approach allows one to determine experimentally observed temperature dependence of the structure period and the order-disorder transition temperature for different oligomeric fraction in systems with different bonding strength. A whole set of parameters of the model used is found for strong, intermediate, and weak coupled systems being poly(4-vinyl pyridine)-dodecyl benzene sulfonic acid [P4VP-(DBSA) x ], P4VP-[Zn(DBS) 2 ] x , and P4VP-3-pentadecyl phenol x [P4VP-(PDP) x ], respectively. A passage from the former two to the latter is shown to cause a crucial decrease in the magnitude of both parameters of hydrogen bonding and self-action, as well as the order-disorder transition temperature

  3. Toxic prefibrillar α-synuclein amyloid oligomers adopt a distinctive antiparallel β-sheet structure.

    Science.gov (United States)

    Celej, María Soledad; Sarroukh, Rabia; Goormaghtigh, Erik; Fidelio, Gerardo D; Ruysschaert, Jean-Marie; Raussens, Vincent

    2012-05-01

    Parkinson's disease is an age-related movement disorder characterized by the presence in the mid-brain of amyloid deposits of the 140-amino-acid protein AS (α-synuclein). AS fibrillation follows a nucleation polymerization pathway involving diverse transient prefibrillar species varying in size and morphology. Similar to other neurodegenerative diseases, cytotoxicity is currently attributed to these prefibrillar species rather than to the insoluble aggregates. Nevertheless, the underlying molecular mechanisms responsible for cytotoxicity remain elusive and structural studies may contribute to the understanding of both the amyloid aggregation mechanism and oligomer-induced toxicity. It is already recognized that soluble oligomeric AS species adopt β-sheet structures that differ from those characterizing the fibrillar structure. In the present study we used ATR (attenuated total reflection)-FTIR (Fourier-transform infrared) spectroscopy, a technique especially sensitive to β-sheet structure, to get a deeper insight into the β-sheet organization within oligomers and fibrils. Careful spectral analysis revealed that AS oligomers adopt an antiparallel β-sheet structure, whereas fibrils adopt a parallel arrangement. The results are discussed in terms of regions of the protein involved in the early β-sheet interactions and the implications of such conformational arrangement for the pathogenicity associated with AS oligomers.

  4. Pigments and oligomers for inks - moving towards the best combination

    International Nuclear Information System (INIS)

    Hutchinson, I.; Smith, S.; Grierson, W.; Devine, E.

    1999-01-01

    The formulation of UV curable printing inks depends on several complex factors. If the individual components of the ink are not complementary, then performance problems can arise. One critical combination is that between the pigment and the oligomer. In a new approach to improve understanding of pigment/oligomer interactions, the resources of a pigment manufacturer and an oligomer manufacturer have been combined to investigate the problem. Initial screening of process yellow pigments and several oligomer types highlighted performance variations which were then examined in more detail

  5. Isolation and Quantification of Polyamide Cyclic Oligomers in Kitchen Utensils and Their Migration into Various Food Simulants

    OpenAIRE

    Abe, Yutaka; Mutsuga, Motoh; Ohno, Hiroyuki; Kawamura, Yoko; Akiyama, Hiroshi

    2016-01-01

    Small amounts of cyclic monomers and oligomers are present in polyamide (PA)-based kitchen utensils. In this study, we isolated eight PA-based cyclic monomers and oligomers from kitchen utensils made from PA6 (a polymer of ε-caprolactam) and PA66 (a polymer of 1,6-diaminohexane and adipic acid). Their structures were identified using high-resolution mass spectrometry and 1H- and 13C-nuclear magnetic resonance spectroscopy, and their residual levels in PA-based kitchen utensils and degree of m...

  6. Isolation and Quantification of Polyamide Cyclic Oligomers in Kitchen Utensils and Their Migration into Various Food Simulants.

    Science.gov (United States)

    Abe, Yutaka; Mutsuga, Motoh; Ohno, Hiroyuki; Kawamura, Yoko; Akiyama, Hiroshi

    2016-01-01

    Small amounts of cyclic monomers and oligomers are present in polyamide (PA)-based kitchen utensils. In this study, we isolated eight PA-based cyclic monomers and oligomers from kitchen utensils made from PA6 (a polymer of ε-caprolactam) and PA66 (a polymer of 1,6-diaminohexane and adipic acid). Their structures were identified using high-resolution mass spectrometry and 1H- and 13C-nuclear magnetic resonance spectroscopy, and their residual levels in PA-based kitchen utensils and degree of migration into food simulants were quantified by high-performance liquid chromatography/mass spectrometry using purchased PA6 monomer and isolated PA66 monomers, and isolated PA6 and PA66 oligomers as calibration standards. Their total residual levels among 23 PA-based kitchen utensils made from PA6, PA66, and copolymers of PA6 and PA66 (PA6/66) ranged from 7.8 to 20 mg/g. Using water, 20% ethanol, and olive oil as food simulants, the total migration levels of the PA monomers and oligomers ranged from 0.66 to 100 μg/cm2 under most examined conditions. However, the total migration levels of the PA66 monomer and oligomers from PA66 and PA6/66 kitchen utensils into 20% ethanol at 95°C were very high (1,700 and 2,200 μg/cm2, respectively) due to swelling by high-temperature ethanol.

  7. Oligomers and Polymers Based on Pentacene Building Blocks

    Science.gov (United States)

    Lehnherr, Dan; Tykwinski, Rik R.

    2010-01-01

    Functionalized pentacene derivatives continue to provide unique materials for organic semiconductor applications. Although oligomers and polymers based on pentacene building blocks remain quite rare, recent synthetic achievements have provided a number of examples with varied structural motifs. This review highlights recent work in this area and, when possible, contrasts the properties of defined-length pentacene oligomers to those of mono- and polymeric systems.

  8. An Open-Circuit Voltage and Power Conversion Efficiency Study of Fullerene Ternary Organic Solar Cells Based on Oligomer/Oligomer and Oligomer/Polymer.

    Science.gov (United States)

    Zhang, Guichuan; Zhou, Cheng; Sun, Chen; Jia, Xiaoe; Xu, Baomin; Ying, Lei; Huang, Fei; Cao, Yong

    2017-07-01

    Variations in the open-circuit voltage (V oc ) of ternary organic solar cells are systematically investigated. The initial study of these devices consists of two electron-donating oligomers, S2 (two units) and S7 (seven units), and the electron-accepting [6,6]-phenyl C71 butyric acid methyl ester (PC 71 BM) and reveals that the V oc is continuously tunable due to the changing energy of the charge transfer state (E ct ) of the active layers. Further investigation suggests that V oc is also continuously tunable upon change in E ct in a ternary blend system that consists of S2 and its corresponding polymer (P11):PC 71 BM. It is interesting to note that higher power conversion efficiencies can be obtained for both S2:S7:PC 71 BM and S2:P11:PC 71 BM ternary systems compared with their binary systems, which can be ascribed to an improved V oc due to the higher E ct and an improved fill factor due to the improved film morphology upon the incorporation of S2. These findings provide a new guideline for the future design of conjugated polymers for achieving higher performance of ternary organic solar cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Regeneration of cello-oligomers via selective depolymerization of cellulose fibers derived from printed paper wastes.

    Science.gov (United States)

    Voon, Lee Ken; Pang, Suh Cem; Chin, Suk Fun

    2016-05-20

    Cellulose extracted from printed paper wastes were selectively depolymerized under controlled conditions into cello-oligomers of controllable chain lengths via dissolution in an ionic liquid, 1-allyl-3-methylimidazolium chloride (AMIMCl), and in the presence of an acid catalyst, Amberlyst 15DRY. The depolymerization process was optimized against reaction temperature, concentration of acid catalyst, and reaction time. Despite rapid initial depolymerization process, the rate of cellulose depolymerization slowed down gradually upon prolonged reaction time, with 75.0 wt% yield of regenerated cello-oligomers (mean Viscosimetric Degree of Polymerization value of 81) obtained after 40 min. The depolymerization of cellulose fibers at 80 °C appeared to proceed via a second-order kinetic reaction with respect to the catalyst concentration of 0.23 mmol H3O(+). As such, the cellulose depolymerization process could afford some degree of control on the degree of polymerization or chain lengths of cello-oligomers formed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. New strategy for stable-isotope-aided, multidimensional NMR spectroscopy of DNA oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Okira; Tate, Shin-Ichi; Kainosho, Masatsune [Tokyo Metropolitan Univ., Tokyo (Japan)

    1994-12-01

    Nuclear Magnetic Resonance (NMR) is the most efficient method for determining the solution structures of biomolecules. By applying multidimensional heteronuclear NMR techniques to {sup 13}C/{sup 15}N-labeled proteins, we can determine the solution structures of proteins with molecular mass of 20 to 30kDa at an accuracy similar to that of x-ray crystallography. Improvements in NMR instrumentation and techniques as well as the development of protein engineering methods for labeling proteins have rapidly advanced multidimensional heteronuclear NMR of proteins. In contrast, multidimensional heteronuclear NMR studies of nucleic acids is less advanced because there were no efficient methods for preparing large amounts of labeled DNA/RNA oligomers. In this report, we focused on the chemical synthesis of DNA oligomers labeled at specific residue(s). RNA oligomers with specific labels, which are difficult to synthesize by the enzyme method, can be synthesized by the chemical method. The specific labels are useful for conformational analysis of larger molecules such as protein-nucleic acid complexes.

  11. HAMLET forms annular oligomers when deposited with phospholipid monolayers.

    Science.gov (United States)

    Baumann, Anne; Gjerde, Anja Underhaug; Ying, Ming; Svanborg, Catharina; Holmsen, Holm; Glomm, Wilhelm R; Martinez, Aurora; Halskau, Oyvind

    2012-04-20

    Recently, the anticancer activity of human α-lactalbumin made lethal to tumor cells (HAMLET) has been linked to its increased membrane affinity in vitro, at neutral pH, and ability to cause leakage relative to the inactive native bovine α-lactalbumin (BLA) protein. In this study, atomic force microscopy resolved membrane distortions and annular oligomers (AOs) produced by HAMLET when deposited at neutral pH on mica together with a negatively charged lipid monolayer. BLA, BAMLET (HAMLET's bovine counterpart) and membrane-binding Peptide C, corresponding to BLA residues 75-100, also form AO-like structures under these conditions but at higher subphase concentrations than HAMLET. The N-terminal Peptide A, which binds to membranes at acidic but not at neutral pH, did not form AOs. This suggests a correlation between the capacity of the proteins/peptides to integrate into the membrane at neutral pH-as observed by liposome content leakage and circular dichroism experiments-and the formation of AOs, albeit at higher concentrations. Formation of AOs, which might be important to HAMLET's tumor toxic action, appears related to the increased tendency of the protein to populate intermediately folded states compared to the native protein, the formation of which is promoted by, but not uniquely dependent on, the oleic acid molecules associated with HAMLET. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Macrocyclic 2,7-Anthrylene Oligomers.

    Science.gov (United States)

    Yamamoto, Yuta; Wakamatsu, Kan; Iwanaga, Tetsuo; Sato, Hiroyasu; Toyota, Shinji

    2016-05-06

    A macrocyclic compound consisting of six 2,7-anthrylene units was successfully synthesized by Ni-mediated coupling of the corresponding dibromo precursor as a novel π-conjugated compound. This compound was sufficiently stable and soluble in organic solvents due to the presence of mesityl groups. X-ray analysis showed that the molecule had a nonplanar and hexagonal wheel-shaped framework of approximately S6 symmetry. The dynamic process between two S6 structures was observed by using the dynamic NMR technique, the barrier being 58 kJ mol(-1) . The spectroscopic properties of the hexamer were compared with those of analogous linear oligomers. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. PT-symmetry management in oligomer systems

    International Nuclear Information System (INIS)

    Horne, R L; Cuevas, J; Kevrekidis, P G; Whitaker, N; Abdullaev, F Kh; Frantzeskakis, D J

    2013-01-01

    We study the effects of management of the PT-symmetric part of the potential within the setting of Schrödinger dimer and trimer oligomer systems. This is done by rapidly modulating in time the gain/loss profile. This gives rise to a number of interesting properties of the system, which are explored at the level of an averaged equation approach. Remarkably, this rapid modulation provides for a controllable expansion of the region of exact PT-symmetry, depending on the strength and frequency of the imposed modulation. The resulting averaged models are analysed theoretically and their exact stationary solutions are translated into time-periodic solutions through the averaging reduction. These are, in turn, compared with the exact periodic solutions of the full non-autonomous PT-symmetry managed problem and very good agreement is found between the two. (paper)

  14. Nanoparticle for delivery of antisense γPNA oligomers targeting CCR5

    OpenAIRE

    Bahal, Raman; McNeer, Nicole Ali; Ly, Danith H.; Saltzman, W. Mark; Glazer, Peter M.

    2013-01-01

    The development of a new class of peptide nucleic acids (PNAs), i.e., gamma PNAs (γPNAs), creates the need for a general and effective method for its delivery into cells for regulating gene expression in mammalian cells. Here we report the antisense activity of a recently developed hydrophilic and biocompatible diethylene glycol (miniPEG)-based gamma peptide nucleic acid called MPγPNAs via its delivery by poly(lactide-co-glycolide) (PLGA)-based nanoparticle system. We show that MPγPNA oligome...

  15. Structural and functional properties of prefibrillar α-synuclein oligomers.

    Science.gov (United States)

    Pieri, Laura; Madiona, Karine; Melki, Ronald

    2016-04-14

    The deposition of fibrillar alpha-synuclein (α-syn) within inclusions (Lewy bodies and Lewy neurites) in neurons and glial cells is a hallmark of synucleinopathies. α-syn populates a variety of assemblies ranging from prefibrillar oligomeric species to fibrils whose specific contribution to neurodegeneration is still unclear. Here, we compare the specific structural and biological properties of distinct soluble prefibrillar α-syn oligomers formed either spontaneously or in the presence of dopamine and glutaraldehyde. We show that both on-fibrillar assembly pathway and distinct dopamine-mediated and glutaraldehyde-cross-linked α-syn oligomers are only slightly effective in perturbing cell membrane integrity and inducing cytotoxicity, while mature fibrils exhibit the highest toxicity. In contrast to low-molecular weight and unstable oligomers, large stable α-syn oligomers seed the aggregation of soluble α-syn within reporter cells although to a lesser extent than mature α-syn fibrils. These oligomers appear elongated in shape. Our findings suggest that α-syn oligomers represent a continuum of species ranging from unstable low molecular weight particles to mature fibrils via stable elongated oligomers composed of more than 15 α-syn monomers that possess seeding capacity.

  16. Electron beam curing polyurethane acrylate oligomer in air

    International Nuclear Information System (INIS)

    Zhu, Zhenkang; Chen, Xing; Zhou, Jichun; Ma, Zue-Teh

    1988-01-01

    It has been found according to our synthesis that a novel kind of polyurethane acrylate oligomer can be cured by electron beam in the presence of oxygen, even at normal atomospheric levels, without any additives. Irradiation of the oligomer with substantially complete cure to a solid non-tacky state is quite remarkable. It has the same gel content (90 %) in air as in nitrogen at dose of 33 kGy. Double bond conversion of the oligomer is about 50 % by I.R. (author)

  17. Molecular size evolution of oligomers in organic aerosols collected in urban atmospheres and generated in a smog chamber.

    Science.gov (United States)

    Kalberer, Markus; Sax, Mirjam; Samburova, Vera

    2006-10-01

    Only a minor fraction of the total organic aerosol mass can be resolved on a molecular level. High molecular weight compounds in organic aerosols have recently gained much attention because this class of compound potentially explains a major fraction of the unexplained organic aerosol mass. These compounds have been identified with different mass spectrometric methods, and compounds with molecular masses up to 1000 Da are found in secondary organic aerosols (SOA) generated from aromatic and terpene precursors in smog chamber experiments. Here, we apply matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to SOA particles from two biogenic precursors, alpha-pinene and isoprene. Similar oligomer patterns are found in these two SOA systems, but also in SOA from trimethylbenzene, an anthropogenic SOA precursor. However, different maxima molecular sizes were measured for these three SOA systems. While oligomers in alpha-pinene and isoprene have sizes mostly below 600-700 Da, they grow up to about 1000 Da in trimethylbenzene-SOA. The final molecular size of the oligomers is reached early during the particle aging process, whereas other particle properties related to aging, such as the overall acid concentration or the oligomer concentration, increase continuously over a much longer time scale. This kinetic behavior of the oligomer molecular size growth can be explained by a chain growth kinetic regime. Similar oligomer mass patterns were measured in aqueous extracts of ambient aerosol samples (measured with the same technique). Distinct differences between summer and winter were observed. In summer a few single mass peaks were measured with much higher intensity than in winter, pointing to a possible difference in the formation processes of these compounds in winter and summer.

  18. Indirubin Derivative 7-Bromoindirubin-3-Oxime (7Bio Attenuates Aβ Oligomer-Induced Cognitive Impairments in Mice

    Directory of Open Access Journals (Sweden)

    Liping Chen

    2017-11-01

    Full Text Available Indirubins are natural occurring alkaloids extracted from indigo dye-containing plants. Indirubins could inhibit various kinases, and might be used to treat chronic myelocytic leukemia, cancer and neurodegenerative disorders. 7-bromoindirubin-3-oxime (7Bio, an indirubin derivative derived from indirubin-3-oxime, possesses inhibitory effects against cyclin-dependent kinase-5 (CDK5 and glycogen synthase kinase-3β (GSK3β, two pharmacological targets of Alzheimer's disease (AD. In this study, we have discovered that 2.3–23.3 μg/kg 7Bio effectively prevented β-amyloid (Aβ oligomer-induced impairments of spatial cognition and recognition without affecting bodyweight and motor functions in mice. Moreover, 7Bio potently inhibited Aβ oligomer-induced expression of interleukin-6 (IL-6 and tumor necrosis factor-α (TNF-α. Furthermore, 7Bio significantly prevented the decreased expression of synapsin-1 and PSD-95, biomarkers of pre-synaptic and post-synaptic proteins in Aβ oligomer-treated mice. The mean optical density (OD with hyper-phosphorylated tau (pTau, glial fibrillary acidic protein (GFAP and CD45 positive staining in the hippocampus of 7Bio-treated mice were significantly decreased compared to those of Aβ oligomer-treated mice. In addition, Western blotting analysis showed that 7Bio attenuated Aβ oligomer-decreased expression of pSer9-GSK3β. Those results suggested that 7Bio could potently inhibit Aβ oligomer-induced neuroinflammation, synaptic impairments, tau hyper-phosphorylation, and activation of astrocytes and microglia, which may contribute to the neuroprotective effects of 7Bio. Based on these findings, we expected that 7Bio might be developed as a novel anti-AD lead compound.

  19. The Effect of H2SO4 Concentration on the Ionic Conductivity of Liquid PMMA Oligomer

    International Nuclear Information System (INIS)

    Norashima Kamaluddin; Famiza Abdul Latif; Han, C.C.; Ruhani Ibrahim; Sharil Fadli Mohamad Zamri; Norashima Kamaluddin; Famiza Abdul Latif; Han, C.C.; Ruhani Ibrahim; Sharil Fadli Mohamad Zamri

    2015-01-01

    To date gel and film type polymer electrolytes have been widely synthesized due to their wide range of electrical properties. However these types of polymer electrolytes exhibit poor mechanical stability and poor electrode-electrolyte contact hence deprive the overall performance of a battery system. Therefore, in order to indulge the advantages of polymer as electrolyte, a new class of polymer electrolyte was synthesized and investigated. In this study, liquid poly(methyl methacrylate) (PMMA) electrolyte was synthesized using the simplest free radical polymerization technique using benzoyl peroxide as the initiator. At this stage, it was found that this liquid PMMA oligomer (MW=3000 g/ mole) has a potential as electrolyte in electrochemical devices. It was found that an ionic conductivity of ∼10 -7 S/ cm at room temperature can be achieved when only small volume of high molarity of sulfuric acid (H 2 SO 4 ) was doped in the liquid PMMA oligomer. The properties of this liquid PMMA oligomer were further investigated using Fourier Transform Infrared Spectroscopy (FTIR). (author)

  20. Structural fingerprints and their evolution during oligomeric vs. oligomer-free amyloid fibril growth.

    Science.gov (United States)

    Foley, Joseph; Hill, Shannon E; Miti, Tatiana; Mulaj, Mentor; Ciesla, Marissa; Robeel, Rhonda; Persichilli, Christopher; Raynes, Rachel; Westerheide, Sandy; Muschol, Martin

    2013-09-28

    Deposits of fibrils formed by disease-specific proteins are the molecular hallmark of such diverse human disorders as Alzheimer's disease, type II diabetes, or rheumatoid arthritis. Amyloid fibril formation by structurally and functionally unrelated proteins exhibits many generic characteristics, most prominently the cross β-sheet structure of their mature fibrils. At the same time, amyloid formation tends to proceed along one of two separate assembly pathways yielding either stiff monomeric filaments or globular oligomers and curvilinear protofibrils. Given the focus on oligomers as major toxic species, the very existence of an oligomer-free assembly pathway is significant. Little is known, though, about the structure of the various intermediates emerging along different pathways and whether the pathways converge towards a common or distinct fibril structures. Using infrared spectroscopy we probed the structural evolution of intermediates and late-stage fibrils formed during in vitro lysozyme amyloid assembly along an oligomeric and oligomer-free pathway. Infrared spectroscopy confirmed that both pathways produced amyloid-specific β-sheet peaks, but at pathway-specific wavenumbers. We further found that the amyloid-specific dye thioflavin T responded to all intermediates along either pathway. The relative amplitudes of thioflavin T fluorescence responses displayed pathway-specific differences and could be utilized for monitoring the structural evolution of intermediates. Pathway-specific structural features obtained from infrared spectroscopy and Thioflavin T responses were identical for fibrils grown at highly acidic or at physiological pH values and showed no discernible effects of protein hydrolysis. Our results suggest that late-stage fibrils formed along either pathway are amyloidogenic in nature, but have distinguishable structural fingerprints. These pathway-specific fingerprints emerge during the earliest aggregation events and persist throughout the

  1. Structural fingerprints and their evolution during oligomeric vs. oligomer-free amyloid fibril growth

    Science.gov (United States)

    Foley, Joseph; Hill, Shannon E.; Miti, Tatiana; Mulaj, Mentor; Ciesla, Marissa; Robeel, Rhonda; Persichilli, Christopher; Raynes, Rachel; Westerheide, Sandy; Muschol, Martin

    2013-09-01

    Deposits of fibrils formed by disease-specific proteins are the molecular hallmark of such diverse human disorders as Alzheimer's disease, type II diabetes, or rheumatoid arthritis. Amyloid fibril formation by structurally and functionally unrelated proteins exhibits many generic characteristics, most prominently the cross β-sheet structure of their mature fibrils. At the same time, amyloid formation tends to proceed along one of two separate assembly pathways yielding either stiff monomeric filaments or globular oligomers and curvilinear protofibrils. Given the focus on oligomers as major toxic species, the very existence of an oligomer-free assembly pathway is significant. Little is known, though, about the structure of the various intermediates emerging along different pathways and whether the pathways converge towards a common or distinct fibril structures. Using infrared spectroscopy we probed the structural evolution of intermediates and late-stage fibrils formed during in vitro lysozyme amyloid assembly along an oligomeric and oligomer-free pathway. Infrared spectroscopy confirmed that both pathways produced amyloid-specific β-sheet peaks, but at pathway-specific wavenumbers. We further found that the amyloid-specific dye thioflavin T responded to all intermediates along either pathway. The relative amplitudes of thioflavin T fluorescence responses displayed pathway-specific differences and could be utilized for monitoring the structural evolution of intermediates. Pathway-specific structural features obtained from infrared spectroscopy and Thioflavin T responses were identical for fibrils grown at highly acidic or at physiological pH values and showed no discernible effects of protein hydrolysis. Our results suggest that late-stage fibrils formed along either pathway are amyloidogenic in nature, but have distinguishable structural fingerprints. These pathway-specific fingerprints emerge during the earliest aggregation events and persist throughout the

  2. SAXS and stability studies of iron-induced oligomers of bacterial frataxin CyaY.

    Directory of Open Access Journals (Sweden)

    Mostafa Fekry

    Full Text Available Frataxin is a highly conserved protein found in both prokaryotes and eukaryotes. It is involved in several central functions in cells, which include iron delivery to biochemical processes, such as heme synthesis, assembly of iron-sulfur clusters (ISC, storage of surplus iron in conditions of iron overload, and repair of ISC in aconitase. Frataxin from different organisms has been shown to undergo iron-dependent oligomerization. At least two different classes of oligomers, with different modes of oligomer packing and stabilization, have been identified. Here, we continue our efforts to explore the factors that control the oligomerization of frataxin from different organisms, and focus on E. coli frataxin CyaY. Using small-angle X-ray scattering (SAXS, we show that higher iron-to-protein ratios lead to larger oligomeric species, and that oligomerization proceeds in a linear fashion as a results of iron oxidation. Native mass spectrometry and online size-exclusion chromatography combined with SAXS show that a dimer is the most common form of CyaY in the presence of iron at atmospheric conditions. Modeling of the dimer using the SAXS data confirms the earlier proposed head-to-tail packing arrangement of monomers. This packing mode brings several conserved acidic residues into close proximity to each other, creating an environment for metal ion binding and possibly even mineralization. Together with negative-stain electron microscopy, the experiments also show that trimers, tetramers, pentamers, and presumably higher-order oligomers may exist in solution. Nano-differential scanning fluorimetry shows that the oligomers have limited stability and may easily dissociate at elevated temperatures. The factors affecting the possible oligomerization mode are discussed.

  3. Antisense Phosphorodiamidate Morpholino Oligomers as Novel Antiviral Compounds

    Directory of Open Access Journals (Sweden)

    Yuchen Nan

    2018-04-01

    Full Text Available Phosphorodiamidate morpholino oligomers (PMO are short single-stranded DNA analogs that are built upon a backbone of morpholine rings connected by phosphorodiamidate linkages. As uncharged nucleic acid analogs, PMO bind to complementary sequences of target mRNA by Watson–Crick base pairing to block protein translation through steric blockade. PMO interference of viral protein translation operates independently of RNase H. Meanwhile, PMO are resistant to a variety of enzymes present in biologic fluids, a characteristic that makes them highly suitable for in vivo applications. Notably, PMO-based therapy for Duchenne muscular dystrophy (DMD has been approved by the United States Food and Drug Administration which is now a hallmark for PMO-based antisense therapy. In this review, the development history of PMO, delivery methods for improving cellular uptake of neutrally charged PMO molecules, past studies of PMO antagonism against RNA and DNA viruses, PMO target selection, and remaining questions of PMO antiviral strategies are discussed in detail and new insights are provided.

  4. Conjugated Polymers and Oligomers: Structural and Soft Matter Aspects

    DEFF Research Database (Denmark)

    This book identifies modern topics and current trends of structural and soft matter aspects of conjugated polymers and oligomers. Each chapter recognizes an active research line where structural perspective dominates research and therefore the book covers fundamental aspects of persistent...

  5. Diffusivities and Viscosities of Poly(ethylene oxide) Oligomers

    KAUST Repository

    Hong, Bingbing; Escobedo, Fernando; Panagiotopoulos, Athanassios Z.

    2010-01-01

    Diffusivities and viscosities of poly(ethylene oxide) (PEO) oligomer melts with 1 to 12 repeat units have been obtained from equilibrium molecular dynamics simulations using the TraPPE-UA force field. The simulations generated diffusion coefficients

  6. Binding Sites for Amyloid-β Oligomers and Synaptic Toxicity

    Science.gov (United States)

    Smith, Levi M.; Strittmatter, Stephen M.

    2017-01-01

    In Alzheimer’s disease (AD), insoluble and fibrillary amyloid-β (Aβ) peptide accumulates in plaques. However, soluble Aβ oligomers are most potent in creating synaptic dysfunction and loss. Therefore, receptors for Aβ oligomers are hypothesized to be the first step in a neuronal cascade leading to dementia. A number of cell-surface proteins have been described as Aβ binding proteins, and one or more are likely to mediate Aβ oligomer toxicity in AD. Cellular prion protein (PrPC) is a high-affinity Aβ oligomer binding site, and a range of data delineates a signaling pathway leading from Aβ complexation with PrPC to neuronal impairment. Further study of Aβ binding proteins will define the molecular basis of this crucial step in AD pathogenesis. PMID:27940601

  7. Organic heterostructures based on arylenevinylene oligomers deposited by MAPLE

    Czech Academy of Sciences Publication Activity Database

    Socol, M.; Preda, N.; Vacareanu, L.; Grigoras, M.; Socol, G.; Mihailescu, I. N.; Stanculescu, F.; Jelínek, Miroslav; Stanculescu, A.; Stoicanescu, M.

    2014-01-01

    Roč. 302, May (2014), s. 216-222 ISSN 0169-4332 Institutional support: RVO:68378271 Keywords : organic heterostructures * MAPLE * oligomer * optoelectronica Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.711, year: 2014

  8. Oligomers and Polymers Based on Pentacene Building Blocks

    Directory of Open Access Journals (Sweden)

    Dan Lehnherr

    2010-04-01

    Full Text Available Functionalized pentacene derivatives continue to provide unique materials for organic semiconductor applications. Although oligomers and polymers based on pentacene building blocks remain quite rare, recent synthetic achievements have provided a number of examples with varied structural motifs. This review highlights recent work in this area and, when possible, contrasts the properties of defined-length pentacene oligomers to those of mono- and polymeric systems.

  9. Biophysical characterization data on Aβ soluble oligomers produced through a method enabling prolonged oligomer stability and biological buffer conditions

    Directory of Open Access Journals (Sweden)

    Amanda C. Crisostomo

    2015-09-01

    Aβ1-40 soluble oligomers are produced that are suitable for biophysical studies requiring sufficient transient stability to exist in their “native” conformation in biological phosphate-saline buffers for extended periods of time. The production involves an initial preparation of highly monomeric Aβ in a phosphate saline buffer that transitions to fibrils and oligomers through time incubation alone, without added detergents or non-aqueous chemicals. This criteria ensures that the only difference between initial monomeric Aβ reactant and subsequent Aβ oligomer products is their degree of peptide assembly. A number of chemical and biophysical methods were used to characterize the monomeric reactants and soluble oligomer and amyloid fibril products, including chemical cross-linking, Western blots, fraction solubility, thioflvain T binding, size exclusion chromatography, transmission electron micrscopy, circular dichroism spectroscopy, and fluorescence resonance energy transfer.

  10. Detection of aniline oligomers on polyaniline-gold interface using resonance Raman scattering.

    Science.gov (United States)

    Trchová, Miroslava; Morávková, Zuzana; Dybal, Jiří; Stejskal, Jaroslav

    2014-01-22

    In situ deposited conducting polyaniline films prepared by the oxidation of aniline with ammonium peroxydisulfate in aqueous media of various acidities on gold and silicon supports were characterized by Raman spectroscopy. Enhanced Raman bands were found in the spectra of polyaniline films produced in the solutions of weak acids or in water on gold surface. These bands were weak for the films prepared in solutions of a strong acid on a gold support. The same bands are present in the Raman spectra of the reaction intermediates deposited during aniline oxidation in water or aqueous solutions of weak or strong acids on silicon removed from the reaction mixture at the beginning of the reaction. Such films are formed by aniline oligomers adsorbed on the surface. They were detected on the polyaniline-gold interface using resonance Raman scattering on the final films deposited on gold. The surface resonance Raman spectroscopy of the monolayer of oligomers found in the bulk polyaniline film makes this method advantageous in surface science, with many applications in electrochemistry, catalysis, and biophysical, polymer, or analytical chemistry.

  11. GalaxyHomomer: a web server for protein homo-oligomer structure prediction from a monomer sequence or structure.

    Science.gov (United States)

    Baek, Minkyung; Park, Taeyong; Heo, Lim; Park, Chiwook; Seok, Chaok

    2017-07-03

    Homo-oligomerization of proteins is abundant in nature, and is often intimately related with the physiological functions of proteins, such as in metabolism, signal transduction or immunity. Information on the homo-oligomer structure is therefore important to obtain a molecular-level understanding of protein functions and their regulation. Currently available web servers predict protein homo-oligomer structures either by template-based modeling using homo-oligomer templates selected from the protein structure database or by ab initio docking of monomer structures resolved by experiment or predicted by computation. The GalaxyHomomer server, freely accessible at http://galaxy.seoklab.org/homomer, carries out template-based modeling, ab initio docking or both depending on the availability of proper oligomer templates. It also incorporates recently developed model refinement methods that can consistently improve model quality. Moreover, the server provides additional options that can be chosen by the user depending on the availability of information on the monomer structure, oligomeric state and locations of unreliable/flexible loops or termini. The performance of the server was better than or comparable to that of other available methods when tested on benchmark sets and in a recent CASP performed in a blind fashion. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  12. Overall and specific migration from multilayer high barrier food contact materials - kinetic study of cyclic polyester oligomers migration.

    Science.gov (United States)

    Úbeda, Sara; Aznar, Margarita; Vera, Paula; Nerín, Cristina; Henríquez, Luis; Taborda, Laura; Restrepo, Claudia

    2017-10-01

    Most multilayer high barrier materials used in food packaging have a polyurethane adhesive layer in their structures. In order to assess the safety of these materials, it is important to determine the compounds intentionally added to the adhesives (IAS) as well as those non-intentionally added substances (NIAS). During the manufacture of polyurethane adhesives, some by-products can be formed, such as cyclic polyester oligomers coming from the reaction between dicarboxylic acids and glycols. Since these compounds are not listed in the Regulation 10/2011/EU, they should not be found in migration above 0.01 mg/kg of simulant. In this study two flexible multilayer packaging materials were used and migration was evaluated in simulant A (ethanol 10% v/v), simulant B (acetic acid 3% w/v) and simulant ethanol 95% v/v during 10 days at 60ºC. Identification and quantification of non-volatile compounds was carried out by UPLC-MS-QTOF. Most of migrants were oligomers such as cyclic polyesters and caprolactam oligomers. Overall migration and specific migration of adipic acid-diethylene glycol and phthalic acid-diethylene glycol were monitored over time and analysed by UPLC-MS-TQ. In most cases, ethanol 95% v/v was the simulant with the highest concentration values. Overall migration kinetics followed a similar pattern than specific migration kinetics.

  13. Amplifying (Im)perfection: The Impact of Crystallinity in Discrete and Disperse Block Co-oligomers.

    Science.gov (United States)

    van Genabeek, Bas; Lamers, Brigitte A G; de Waal, Bas F M; van Son, Martin H C; Palmans, Anja R A; Meijer, E W

    2017-10-25

    Crystallinity is seldomly utilized as part of the microphase segregation process in ultralow-molecular-weight block copolymers. Here, we show the preparation of two types of discrete, semicrystalline block co-oligomers, comprising an amorphous oligodimethylsiloxane block and a crystalline oligo-l-lactic acid or oligomethylene block. The self-assembly of these discrete materials results in lamellar structures with unforeseen uniformity in the domain spacing. A systematic introduction of dispersity reveals the extreme sensitivity of the microphase segregation process toward chain length dispersity in the crystalline block.

  14. Isolation and Quantification of Polyamide Cyclic Oligomers in Kitchen Utensils and Their Migration into Various Food Simulants.

    Directory of Open Access Journals (Sweden)

    Yutaka Abe

    Full Text Available Small amounts of cyclic monomers and oligomers are present in polyamide (PA-based kitchen utensils. In this study, we isolated eight PA-based cyclic monomers and oligomers from kitchen utensils made from PA6 (a polymer of ε-caprolactam and PA66 (a polymer of 1,6-diaminohexane and adipic acid. Their structures were identified using high-resolution mass spectrometry and 1H- and 13C-nuclear magnetic resonance spectroscopy, and their residual levels in PA-based kitchen utensils and degree of migration into food simulants were quantified by high-performance liquid chromatography/mass spectrometry using purchased PA6 monomer and isolated PA66 monomers, and isolated PA6 and PA66 oligomers as calibration standards. Their total residual levels among 23 PA-based kitchen utensils made from PA6, PA66, and copolymers of PA6 and PA66 (PA6/66 ranged from 7.8 to 20 mg/g. Using water, 20% ethanol, and olive oil as food simulants, the total migration levels of the PA monomers and oligomers ranged from 0.66 to 100 μg/cm2 under most examined conditions. However, the total migration levels of the PA66 monomer and oligomers from PA66 and PA6/66 kitchen utensils into 20% ethanol at 95°C were very high (1,700 and 2,200 μg/cm2, respectively due to swelling by high-temperature ethanol.

  15. Nanoparticle for delivery of antisense γPNA oligomers targeting CCR5.

    Science.gov (United States)

    Bahal, Raman; McNeer, Nicole Ali; Ly, Danith H; Saltzman, W Mark; Glazer, Peter M

    2013-01-01

    The development of a new class of peptide nucleic acids (PNAs), i.e., gamma PNAs (γPNAs), creates the need for a general and effective method for its delivery into cells for regulating gene expression in mammalian cells. Here we report the antisense activity of a recently developed hydrophilic and biocompatible diethylene glycol (miniPEG)-based gamma peptide nucleic acid called MPγPNAs via its delivery by poly(lactide-co-glycolide) (PLGA)-based nanoparticle system. We show that MPγPNA oligomers designed to bind to the selective region of chemokine receptor 5 (CC R5) transcript, induce potent and sequence-specific antisense effects as compared with regular PNA oligomers. In addition, PLGA nanoparticle delivery of MPγPNAs is not toxic to the cells. The findings reported in this study provide a combination of γPNA technology and PLGA-based nanoparticle delivery method for regulating gene expression in live cells via the antisense mechanism.

  16. Synthesis, Anti-HCV, Antioxidant and Reduction of Intracellular Reactive Oxygen Species Generation of a Chlorogenic Acid Analogue with an Amide Bond Replacing the Ester Bond.

    Science.gov (United States)

    Wang, Ling-Na; Wang, Wei; Hattori, Masao; Daneshtalab, Mohsen; Ma, Chao-Mei

    2016-06-08

    Chlorogenic acid is a well known natural product with important bioactivities. It contains an ester bond formed between the COOH of caffeic acid and the 3-OH of quinic acid. We synthesized a chlorogenic acid analogue, 3α-caffeoylquinic acid amide, using caffeic and quinic acids as starting materials. The caffeoylquinc acid amide was found to be much more stable than chlorogenic acid and showed anti-Hepatitis C virus (anti-HCV) activity with a potency similar to chlorogenic acid. The caffeoylquinc acid amide potently protected HepG2 cells against oxidative stress induced by tert-butyl hydroperoxide.

  17. Mass Spectrometric Characterization of Oligomers in Pseudomonas aeruginosa Azurin Solutions

    Czech Academy of Sciences Publication Activity Database

    Sokolová, L.; Williamson, H.; Sýkora, Jan; Hof, Martin; Gray, H. B.; Brutschy, B.; Vlček, Antonín

    2011-01-01

    Roč. 115, č. 16 (2011), s. 4790-4800 ISSN 1520-6106 R&D Projects: GA MŠk(CZ) ME10124; GA MŠk(CZ) LC06063 Institutional research plan: CEZ:AV0Z40400503 Keywords : mass spectrometry * oligomers * pseudomonas aeruginosa azurin solutions Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.696, year: 2011

  18. Coronavirus nucleocapsid proteins assemble constitutively in high molecular oligomers

    NARCIS (Netherlands)

    Cong, Yingying; Kriegenburg, Franziska; de Haan, Cornelis A. M.; Reggiori, Fulvio

    2017-01-01

    Coronaviruses (CoV) are enveloped viruses and rely on their nucleocapsid N protein to incorporate the positive-stranded genomic RNA into the virions. CoV N proteins form oligomers but the mechanism and relevance underlying their multimerization remain to be fully understood. Using in vitro pull-down

  19. Shaking alone induces de novo conversion of recombinant prion proteins to β-sheet rich oligomers and fibrils.

    Directory of Open Access Journals (Sweden)

    Carol L Ladner-Keay

    Full Text Available The formation of β-sheet rich prion oligomers and fibrils from native prion protein (PrP is thought to be a key step in the development of prion diseases. Many methods are available to convert recombinant prion protein into β-sheet rich fibrils using various chemical denaturants (urea, SDS, GdnHCl, high temperature, phospholipids, or mildly acidic conditions (pH 4. Many of these methods also require shaking or another form of agitation to complete the conversion process. We have identified that shaking alone causes the conversion of recombinant PrP to β-sheet rich oligomers and fibrils at near physiological pH (pH 5.5 to pH 6.2 and temperature. This conversion does not require any denaturant, detergent, or any other chemical cofactor. Interestingly, this conversion does not occur when the water-air interface is eliminated in the shaken sample. We have analyzed shaking-induced conversion using circular dichroism, resolution enhanced native acidic gel electrophoresis (RENAGE, electron microscopy, Fourier transform infrared spectroscopy, thioflavin T fluorescence and proteinase K resistance. Our results show that shaking causes the formation of β-sheet rich oligomers with a population distribution ranging from octamers to dodecamers and that further shaking causes a transition to β-sheet fibrils. In addition, we show that shaking-induced conversion occurs for a wide range of full-length and truncated constructs of mouse, hamster and cervid prion proteins. We propose that this method of conversion provides a robust, reproducible and easily accessible model for scrapie-like amyloid formation, allowing the generation of milligram quantities of physiologically stable β-sheet rich oligomers and fibrils. These results may also have interesting implications regarding our understanding of prion conversion and propagation both within the brain and via techniques such as protein misfolding cyclic amplification (PMCA and quaking induced conversion (QuIC.

  20. Interpenetrating polymer networks based on cyanate ester and fluorinated ethynyl-terminated imide oligomers

    Directory of Open Access Journals (Sweden)

    Y. Wen

    2017-12-01

    Full Text Available Highly soluble fluorinated ethynyl-terminated imide (FETI oligomers were prepared via a conventional one-step method in m-cresol, using 4, 4′-(hexafluoroisopropylidene diphthalic anhydride and 2, 2′-bis(trifluoromethyl benzidine as the monomers, and ethynylphthalic anhydride as the end-capper; then interpenetrating polymer networks (IPN were formulated from FETI oligomers and bisphenol A dicyanate ester (BADCy through a solvent-free procedure, and their thermal, mechanical, and dielectric properties were fully characterized. The curing mechanism was studied by model reactions using nitrogen nuclear magnetic resonance. As evidenced by differential scanning calorimetry analysis and rheological measurements, the FETI/BADCy blends exhibited lower curing temperature and shorter gelation time in comparison with pure BADCy due to the catalytic effects of ethynyl and residue amic acid groups. The properties of IPNs were fully compared with those of polycyanurate, and the results revealed that the incorporation of FETI into cyanate ester resins could significantly improve the toughness, glass transition temperatures, mechanical and dielectric properties of the resultant IPNs.

  1. Antioxidant Activities and Caffeic Acid Content in New Zealand Asparagus (Asparagus officinalis Roots Extracts

    Directory of Open Access Journals (Sweden)

    Abbey Symes

    2018-04-01

    Full Text Available Asparagus officinalis are perennial plants that require re-planting every 10–20 years. The roots are traditionally mulched in the soil or treated as waste. The A. officinalis roots (AR contain valuable bioactive compounds that may have some health benefiting properties. The aim of this study was to investigate the total polyphenol and flavonoid contents (TPC and TFC, respectively and antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH, Oxygen Radical Absorbance Capacity (ORAC and Ferric Reducing/Antioxidant Power (FRAP assays activities of New Zealand AR extract. The antioxidant activity decreased with a longer extraction time.

  2. OH-radical induced degradation of hydroxybenzoic- and hydroxycinnamic acids and formation of aromatic products-A gamma radiolysis study

    Energy Technology Data Exchange (ETDEWEB)

    Krimmel, Birgit; Swoboda, Friederike [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology (Austria); Solar, Sonja, E-mail: sonja.solar@univie.ac.a [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology (Austria); Reznicek, Gottfried [Department of Pharmacognosy, Althanstrasse 14, A-1090 Vienna (Austria)

    2010-12-15

    The OH-radical induced degradation of hydroxybenzoic acids (HBA), hydroxycinnamic acids (HCiA) and methoxylated derivatives, as well as of chlorogenic acid and rosmarinic acid was studied by gamma radiolysis in aerated aqueous solutions. Primary aromatic products resulting from an OH-radical attachment to the ring (hydroxylation), to the position occupied by the methoxyl group (replacement -OCH{sub 3} by -OH) as well as to the propenoic acid side chain of the cinnamic acids (benzaldehyde formations) were analysed by HPLC-UV and LC-ESI-MS. A comparison of the extent of these processes is given for 3,4-dihydroxybenzoic acid, vanillic acid, isovanillic acid, syringic acid, cinnamic acid, 4-hydroxycinnamic acid, caffeic acid, ferulic acid, isoferulic acid, chlorogenic acid, and rosmarinic acid. For all cinnamic acids and derivatives benzaldehydes were significant oxidation products. With the release of caffeic acid from chlorogenic acid the cleavage of a phenolic glycoside could be demonstrated. Reaction mechanisms are discussed.

  3. Development of a radiochromic ferric oligomer hydrogel

    International Nuclear Information System (INIS)

    Jordan, Kevin; Sekimoto, Masaya

    2010-01-01

    Ferrous gelatin hydrogels were prepared by using sulphuric acid concentrations lower than required to maintain radiation induced ferric ions fully hydrated. The ferric hydroxyl species that are produced following irradiation exhibit a radiochromic response that can be probed with blue light. The dose distribution shapes were stable in time, indicating no long term diffusion. An over response to dose gradients was observed both in one centimeter cuvette samples and litre volumes probed with optical cone beam CT. This ferrous hydrogel may represent a model system for studying iron radiochemistry in biological systems.

  4. Charge transfer in conjugated oligomers encapsulated into carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Almadori, Y.; Alvarez, L.; Michel, T.; Le Parc, R.; Bantignies, J.L.; Hermet, P.; Sauvajol, J.L. [Laboratoire Charles Coulomb UMR 5521, Universite Montpellier 2, 34095 Montpellier (France); Laboratoire Charles Coulomb UMR 5521, CNRS, 34095 Montpellier (France); Arenal, R. [Laboratoire d' Etude des Microstructures, CNRS-ONERA, 92322 Chatillon (France); Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragon, U. Zaragoza, 50018 Zaragoza (Spain); Babaa, R. [Laboratoire de Chimie des Surfaces et Interfaces, CEA, IRAMIS, SPCSI, 91191 Gif-sur-Yvette Cedex (France); Chemical Engineering Department, University of Technology PETRONAS, UTP, Ipoh-Perak (Malaysia); Jouselme, B.; Palacin, S. [Laboratoire de Chimie des Surfaces et Interfaces, CEA, IRAMIS, SPCSI, 91191 Gif-sur-Yvette Cedex (France)

    2011-11-15

    This study deals with a hybrid system consisting in quaterthiophene derivative encapsulated inside single-walled and multi-walled carbon nanotubes. Investigations of the encapsulation step are performed by transmission electron microscopy. Raman spectroscopy data point out different behaviors depending on the laser excitation energy with respect to the optical absorption of quaterthiophene. At low excitation energy (far from the oligomer resonance window) there is no significant modification of the Raman spectra before and after encapsulation. By contrast, at high excitation energy (close to the oligomer resonance window), Raman spectra exhibit a G-band shift together with an important RBM intensity loss, suggesting a significant charge transfer between the inserted molecule and the host nanotubes. Those results suggest a photo induced process leading to a significant charge transfer. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Some biological actions of PEG-conjugated RNase A oligomers

    Czech Academy of Sciences Publication Activity Database

    Poučková, P.; Škvor, J.; Gotte, G.; Vottariello, F.; Slavík, Tomáš; Matoušek, Josef; Laurents, D. V.; Libonati, M.; Souček, J.

    2006-01-01

    Roč. 53, č. 1 (2006), s. 79-85 ISSN 0028-2685 R&D Projects: GA ČR GA523/04/0755; GA MZd NR8233 Grant - others:Spanish Ministerio de Ciencia y Technologia BQU2003-05227 Institutional research plan: CEZ:AV0Z50450515 Keywords : RNase A oligomers * polyethylene glycol conjugates * anti-tumour activity Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.247, year: 2006

  6. α-Synuclein oligomers and clinical implications for Parkinson disease

    Science.gov (United States)

    Kalia, Lorraine V.; Kalia, Suneil K.; McLean, Pamela J.; Lozano, Andres M.; Lang, Anthony E.

    2012-01-01

    Protein aggregation within the central nervous system has been recognized as a defining feature of neurodegenerative diseases since the early 20th century. Since that time, there has been a growing list of neurodegenerative disorders, including Parkinson disease, which are characterized by inclusions of specific pathogenic proteins. This has led to the long-held dogma that these characteristic protein inclusions, which are composed of large insoluble fibrillar protein aggregates and visible by light microscopy, are responsible for cell death in these diseases. However, the correlation between protein inclusion formation and cytotoxicity is inconsistent suggesting another form of the pathogenic proteins may be contributing to neurodegeneration. There is emerging evidence implicating soluble oligomers, smaller protein aggregates not detectable by conventional microscopy, as potential culprits in the pathogenesis of neurodegenerative diseases. The protein α-synuclein is well recognized to contribute to the pathogenesis of Parkinson disease and is the major component of Lewy bodies and Lewy neurites. However, α-synuclein also forms oligomeric species with certain conformations being toxic to cells. The mechanisms by which these α-synuclein oligomers cause cell death are being actively investigated as they may provide new strategies for diagnosis and treatment of Parkinson disease and related disorders. Here we review the possible role of α-synuclein oligomers in cell death in Parkinson disease and discuss the potential clinical implications. PMID:23225525

  7. Interchain interactions in charged diacetylenic oligomers carrying bulk substituents revisited

    International Nuclear Information System (INIS)

    Ottonelli, M.; Izzo, G.M.M.; Comoretto, D.; Musso, G.F.; Dellepiane, G.

    2006-01-01

    We are studying how the electronic properties of an aggregate, built with conjugated oligomers carrying bulk substituents, are affected by intermolecular interactions. In this paper we apply the CEO (Collective Electronic Oscillator) method, on the basis of the semiempirical INDO/S Hamiltonian, to compute the electronic density matrix modifications following the photon absorption in a doubly charged cluster of two units of a fully carbazolyl-substituted oligodiacetylene tetramer, taken as a model system. The picture that had emerged from our previous calculations based on the less sophisticated CIS (Configuration Interaction including Singles) approach is seen to be confirmed. Despite the large separation between the backbones, a through-space charge transfer occurs between the two oligomers due to the fact that the excess charge, contrary to what is generally believed, is not localized on the conjugated backbone, but is spread out over the carbazolyl moieties of the charged molecule. Consideration of this kind of interaction improves the theoretical results obtained for the isolated charged oligomer chain, and aids in better explaining some features of the experimental photoinduced spectra of the corresponding polymer

  8. Synthesis of soybean oil-based thiol oligomers.

    Science.gov (United States)

    Wu, Jennifer F; Fernando, Shashi; Weerasinghe, Dimuthu; Chen, Zhigang; Webster, Dean C

    2011-08-22

    Industrial grade soybean oil (SBO) and thiols were reacted to generate thiol-functionalized oligomers via a thermal, free radical initiated thiol-ene reaction between the SBO double bond moieties and the thiol functional groups. The effect of the reaction conditions, including thiol concentration, catalyst loading level, reaction time, and atmosphere, on the molecular weight and the conversion to the resultant soy-thiols were examined in a combinatorial high-throughput fashion using parallel synthesis, combinatorial FTIR, and rapid gel permeation chromatography (GPC). High thiol functionality and concentration, high thermal free radical catalyst concentration, long reaction time, and the use of a nitrogen reaction atmosphere were found to favor fast consumption of the SBO, and produced high molecular weight products. The thiol conversion during the reaction was inversely affected by a high thiol concentration, but was favored by a long reaction time and an air reaction atmosphere. These experimental observations were explained by the initial low affinity of the SBO and thiol, and the improved affinity between the generated soy-thiol oligomers and unreacted SBO during the reaction. The synthesized soy-thiol oligomers can be used for renewable thiol-ene UV curable materials and high molecular solids and thiourethane thermal cure materials. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Aβ42 oligomers selectively disrupt neuronal calcium release.

    Science.gov (United States)

    Lazzari, Cristian; Kipanyula, Maulilio J; Agostini, Mario; Pozzan, Tullio; Fasolato, Cristina

    2015-02-01

    Accumulation of amyloid-β (Aβ) peptides correlates with aging and progression of Alzheimer's disease (AD). Aβ peptides, which cause early synaptic dysfunctions, spine loss, and memory deficits, also disturb intracellular Ca(2+) homeostasis. By cytosolic and endoplasmic reticulum Ca(2+) measurements, we here define the short-term effects of synthetic Aβ42 on neuronal Ca(2+) dynamics. When applied acutely at submicromolar concentration, as either oligomers or monomers, Aβ42 did not cause Ca(2+) release or Ca(2+) influx. Similarly, 1-hour treatment with Aβ42 modified neither the resting cytosolic Ca(2+) level nor the long-lasting Ca(2+) influx caused by KCl-induced depolarization. In contrast, Aβ42 oligomers, but not monomers, significantly altered Ca(2+) release from stores with opposite effects on inositol 1,4,5-trisphosphate (IP3)- and caffeine-induced Ca(2+) mobilization without alteration of the total store Ca(2+) content. Ca(2+) dysregulation by Aβ42 oligomers involves metabotropic glutamate receptor 5 and requires network activity and the intact exo-endocytotic machinery, being prevented by tetrodotoxin and tetanus toxin. These findings support the idea that Ca(2+) store dysfunction is directly involved in Aβ42 neurotoxicity and represents a potential therapeutic target in AD-like dementia. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Characterization of radiation modified κ-carrageenan oligomers for bio-based materials development

    International Nuclear Information System (INIS)

    Abad, Lucille V.; Relleve, Lorna S.; Aranilla, Charito T.; Racadio, Darwin T.; Dela Rosa, Alumanda M.

    2011-01-01

    κ-carrageenan oligomers are known to have several biological activities such as anti-HIV, anti-herpes, antitumor and antioxidant properties. Recent progress in the development of radiation modified κ-carrageenan has resulted in new applications such as plant growth promoter, radiation dose indicator and hydrogels for wound dressing. This presentation would touch on the changes in chemical structure, gelation and conformational transition behavior and molecular size of κ-carrageenan at doses from 0 to 200 kGy and would be correlated to these functions for the development of bio-based materials. Chemical and spectral analyses were carried out using UV-Vis spectroscopy, FT-IR spectroscopy, NMR spectroscopy, reducing sugar analysis, free sulfate and carboxylic acid analysis. The chemical and spectral analyses of the radiolytic products indicated increasing reducing sugars, carbonyl, carboxylic acids, and sulfates with increasing doses which reached a maximum level at a certain dose depending on the irradiation condition. Values were very much lower in solid irradiation (in vacuum and in air) as compared to aqueous irradiation. NMR data also revealed an intact structure of the oligomer irradiated at 100 kGy in the specific fraction that contains an Mw = (3-10) kDa. κ-carrageenan oligomers exhibited antioxidant properties as determined by hydroxyl radical scavenging activity, reducing power and DPPH radical scavenging capacity assay. The degree of oxidative inhibition increased with increasing dose which can be attributed to higher reducing sugar. Dynamic light scattering (DLS) experiments showed that a dose of up to 50 kGy, sol-gelation transition was still observed. Beyond 50 kGy, no gelation took place, instead appearance of fast relax-carrageenan mode in characteristic decay time function was observed at doses of (75-150) kGy. Optimum peak intensity was found at 100 kGy (mol wt. 5-10 kDa) which coincides with the optimum plant growth promoter effect in κ

  11. Neuroprotection comparison of chlorogenic acid and its metabolites against mechanistically distinct cell death-inducing agents in cultured cerebellar granule neurons.

    Science.gov (United States)

    Taram, Faten; Winter, Aimee N; Linseman, Daniel A

    2016-10-01

    While the number of patients diagnosed with neurodegenerative disorders like Alzheimer's disease, amyotrophic lateral sclerosis, and Parkinson's disease is increasing, there are currently no effective treatments that significantly limit the neuronal cell death underlying these diseases. Chlorogenic acid (CGA), a polyphenolic compound found in high concentration in coffee, is known to possess antioxidant and free radical scavenging activity. In this study, we investigated the neuroprotective effects of CGA and its major metabolites in primary cultures of rat cerebellar granule neurons. We show that CGA and caffeic acid displayed a dramatic protective effect against the nitric oxide donor, sodium nitroprusside. In marked contrast, ferulic acid and quinic acid had no protective effect against this nitrosative stress. While CGA and quinic acid had no protective effect against glutamate-induced cell death, caffeic acid and ferulic acid significantly protected neurons from excitotoxicity. Finally, caffeic acid was the only compound to display significant protective activity against hydrogen peroxide, proteasome inhibition, caspase-dependent intrinsic apoptosis, and endoplasmic reticulum stress. These results indicate that caffeic acid displays a much broader profile of neuroprotection against a diverse range of stressors than its parent polyphenol, CGA, or the other major metabolites, ferulic acid and quinic acid. We conclude that caffeic acid is a promising candidate for testing in pre-clinical models of neurodegeneration. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Intracerebroventricular Administration of Amyloid β-protein Oligomers Selectively Increases Dorsal Hippocampal Dialysate Glutamate Levels in the Awake Rat

    Directory of Open Access Journals (Sweden)

    Sean D. O’Shea

    2008-11-01

    Full Text Available Extensive evidence supports an important role for soluble oligomers of the amyloid β-protein (Aβ in Alzheimer’s Disease pathogenesis. In the present study we combined intracerebroventricular (icv injections with brain microdialysis technology in the fully conscious rat to assess the effects of icv administered SDS-stable low-n Aβ oligomers (principally dimers and trimers on excitatory and inhibitory amino acid transmission in the ipsilateral dorsal hippocampus. Microdialysis was employed to assess the effect of icv administration of Aβ monomers and Aβ oligomers on dialysate glutamate, aspartate and GABA levels in the dorsal hippocampus. Administration of Aβ oligomers was associated with a +183% increase (p<0.0001 vs. Aβ monomer-injected control in dorsal hippocampal glutamate levels which was still increasing at the end of the experiment (260 min, whereas aspartate and GABA levels were unaffected throughout. These findings demonstrate that icv administration and microdialysis technology can be successfully combined in the awake rat and suggests that altered dorsal hippocampal glutamate transmission may be a useful target for pharmacological intervention in Alzheimer’s Disease.

  13. Effects of lattice fluctuations on electronic transmission in metal/conjugated-oligomer/metal structures

    International Nuclear Information System (INIS)

    Yu, Z.G.; Smith, D.L.; Saxena, A.; Bishop, A.R.

    1997-01-01

    The electronic transmission across metal/conjugated-oligomer/metal structures in the presence of lattice fluctuations is studied for short oligomer chains. The lattice fluctuations are approximated by static white noise disorder. Resonant transmission occurs when the energy of an incoming electron coincides with a discrete electronic level of the oligomer. The corresponding transmission peak diminishes in intensity with increasing disorder strength. Because of disorder there is an enhancement of the electronic transmission for energies that lie within the electronic gap of the oligomer. If fluctuations are sufficiently strong, a transmission peak within the gap is found at the midgap energy E=0 for degenerate conjugated oligomers (e.g., trans-polyacetylene) and E≠0 for AB-type degenerate oligomers. These results can be interpreted in terms of soliton-antisoliton states created by lattice fluctuations. copyright 1997 The American Physical Society

  14. Synthesis of Dicyclopentadiene Oligomer Over Nanoporous Al-MCM-41 Catalysts.

    Science.gov (United States)

    Park, Eunseo; Kim, Jinhan; Yim, Jin-Heong; Han, Jeongsik; Kwon, Tae Soo; Park, Y K; Jeon, Jong-Ki

    2016-05-01

    One step reaction composed of DCPD oligomerization and DCPD oligomer isomerization was investigated over nanoporous Al-MCM-41 catalysts. The effects of aluminum grafting over MCM-41 on the catalyst characteristics were studied with respect to the synthesis of TCPD isomer. Physical and chemical properties of the catalysts were analyzed by N2 adsorption, temperature-programmed desorption of ammonia, and infrared spectroscopy of adsorbed pyridine. The overall number of acid sites as well as the number of Lewis acid sites increased with increasing of aluminum content over MCM-41. When utilizing MCM-41 and Al-MCM-41 as the catalyst, DCPD oligomerization reaction activity greatly increased compared to the thermal reaction. The highest TCPD isomer selectivity over the Al-MCM-41 catalyst with the highest aluminum content could be ascribed to the largest amount of acid sites. This study showed an increased level of TCPD isomer selectivity by an increasing level of Lewis acid sites through aluminum addition over MCM-41.

  15. Enzymatic Extraction of Hydroxycinnamic Acids from Coffee Pulp

    Directory of Open Access Journals (Sweden)

    Ernesto Favela-Torres

    2011-01-01

    Full Text Available Ferulic, caffeic, p-coumaric and chlorogenic acids are classified as hydroxycinnamic acids, presenting anticarcinogenic, anti-inflammatory and antioxidant properties. In this work, enzymatic extraction has been studied in order to extract high value-added products like hydroxycinnamic acids from coffee pulp. A commercial pectinase and enzyme extract produced by Rhizomucor pusillus strain 23aIV in solid-state fermentation using olive oil or coffee pulp (CP as an inducer of the feruloyl esterase activity were evaluated separately and mixed. The total content (covalently linked and free of ferulic, caffeic, p-coumaric and chlorogenic acids was 5276 mg per kg of coffee pulp. Distribution was as follows (in %: chlorogenic acid 58.7, caffeic acid 37.6, ferulic acid 2.1 and p-coumaric acid 1.5. Most of the hydroxycinnamic acids were covalently bound to the cell wall (in %: p-coumaric acid 97.2, caffeic acid 94.4, chlorogenic acid 76.9 and ferulic acid 73.4. The content of covalently linked hydroxycinnamic acid was used to calculate the enzyme extraction yield. The maximum carbon dioxide rate for the solid-state fermentation using olive oil as an inducer was higher and it was reached in a short cultivation time. Nevertheless, the feruloyl esterase (FAE activity (units per mg of protein obtained in the fermentation using CP as an inducer was 31.8 % higher in comparison with that obtained in the fermentation using olive oil as the inducer. To our knowledge, this is the first report indicating the composition of both esterified and free ferulic, caffeic, p-coumaric and chlorogenic acids in coffee pulp. The highest yield of extraction of hydroxycinnamic acids was obtained by mixing the produced enzyme extract using coffee pulp as an inducer and a commercial pectinase. Extraction yields were as follows (in %: chlorogenic acid 54.4, ferulic acid 19.8, p-coumaric acid 7.2 and caffeic acid 2.3. An important increase in the added value of coffee pulp was mainly

  16. Fibril specific, conformation dependent antibodies recognize a generic epitope common to amyloid fibrils and fibrillar oligomers that is absent in prefibrillar oligomers

    Directory of Open Access Journals (Sweden)

    Rasool Suhail

    2007-09-01

    Full Text Available Abstract Background Amyloid-related degenerative diseases are associated with the accumulation of misfolded proteins as amyloid fibrils in tissue. In Alzheimer disease (AD, amyloid accumulates in several distinct types of insoluble plaque deposits, intracellular Aβ and as soluble oligomers and the relationships between these deposits and their pathological significance remains unclear. Conformation dependent antibodies have been reported that specifically recognize distinct assembly states of amyloids, including prefibrillar oligomers and fibrils. Results We immunized rabbits with a morphologically homogeneous population of Aβ42 fibrils. The resulting immune serum (OC specifically recognizes fibrils, but not random coil monomer or prefibrillar oligomers, indicating fibrils display a distinct conformation dependent epitope that is absent in prefibrillar oligomers. The fibril epitope is also displayed by fibrils of other types of amyloids, indicating that the epitope is a generic feature of the polypeptide backbone. The fibril specific antibody also recognizes 100,000 × G soluble fibrillar oligomers ranging in size from dimer to greater than 250 kDa on western blots. The fibrillar oligomers recognized by OC are immunologically distinct from prefibrillar oligomers recognized by A11, even though their sizes overlap broadly, indicating that size is not a reliable indicator of oligomer conformation. The immune response to prefibrillar oligomers and fibrils is not sequence specific and antisera of the same specificity are produced in response to immunization with islet amyloid polypeptide prefibrillar oligomer mimics and fibrils. The fibril specific antibodies stain all types of amyloid deposits in human AD brain. Diffuse amyloid deposits stain intensely with anti-fibril antibody although they are thioflavin S negative, suggesting that they are indeed fibrillar in conformation. OC also stains islet amyloid deposits in transgenic mouse models of type

  17. Inactivation of lipoprotein lipase occurs on the surface of THP-1 macrophages where oligomers of angiopoietin-like protein 4 are formed

    Energy Technology Data Exchange (ETDEWEB)

    Makoveichuk, Elena; Sukonina, Valentina; Kroupa, Olessia [Department of Medical Biosciences, Physiological Chemistry Umea University, SE-901 87 Umea (Sweden); Thulin, Petra; Ehrenborg, Ewa [Atherosclerosis Research Unit, Department of Medicine, Karolinska Institutet, SE-171 76 Stockholm (Sweden); Olivecrona, Thomas [Department of Medical Biosciences, Physiological Chemistry Umea University, SE-901 87 Umea (Sweden); Olivecrona, Gunilla, E-mail: Gunilla.Olivecrona@medbio.umu.se [Department of Medical Biosciences, Physiological Chemistry Umea University, SE-901 87 Umea (Sweden)

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer Lipoprotein lipase (LPL) activity is controlled by ANGPTL4 in THP-1 macrophages. Black-Right-Pointing-Pointer Both LPL and ANGPTL4 bind to THP-1 macrophages in a heparin-releasable fashion. Black-Right-Pointing-Pointer Only monomers of ANGPTL4 are present within THP-1 macrophages. Black-Right-Pointing-Pointer Covalent oligomers of ANGPTL4 appear on cell surface and in medium. Black-Right-Pointing-Pointer Inactivation of LPL coincide with ANGPTL4 oligomer formation on cell surfaces. -- Abstract: Lipoprotein lipase (LPL) hydrolyzes triglycerides in plasma lipoproteins causing release of fatty acids for metabolic purposes in muscles and adipose tissue. LPL in macrophages in the artery wall may, however, promote foam cell formation and atherosclerosis. Angiopoietin-like protein (ANGPTL) 4 inactivates LPL and ANGPTL4 expression is controlled by peroxisome proliferator-activated receptors (PPAR). The mechanisms for inactivation of LPL by ANGPTL4 was studied in THP-1 macrophages where active LPL is associated with cell surfaces in a heparin-releasable form, while LPL in the culture medium is mostly inactive. The PPAR{delta} agonist GW501516 had no effect on LPL mRNA, but increased ANGPTL4 mRNA and caused a marked reduction of the heparin-releasable LPL activity concomitantly with accumulation of inactive, monomeric LPL in the medium. Intracellular ANGPTL4 was monomeric, while dimers and tetramers of ANGPTL4 were present in the heparin-releasable fraction and medium. GW501516 caused an increase in the amount of ANGPTL4 oligomers on the cell surface that paralleled the decrease in LPL activity. Actinomycin D blocked the effects of GW501516 on ANGPTL4 oligomer formation and prevented the inactivation of LPL. Antibodies against ANGPTL4 interfered with the inactivation of LPL. We conclude that inactivation of LPL in THP-1 macrophages primarily occurs on the cell surface where oligomers of ANGPTL4 are formed.

  18. Inactivation of lipoprotein lipase occurs on the surface of THP-1 macrophages where oligomers of angiopoietin-like protein 4 are formed

    International Nuclear Information System (INIS)

    Makoveichuk, Elena; Sukonina, Valentina; Kroupa, Olessia; Thulin, Petra; Ehrenborg, Ewa; Olivecrona, Thomas; Olivecrona, Gunilla

    2012-01-01

    Highlights: ► Lipoprotein lipase (LPL) activity is controlled by ANGPTL4 in THP-1 macrophages. ► Both LPL and ANGPTL4 bind to THP-1 macrophages in a heparin-releasable fashion. ► Only monomers of ANGPTL4 are present within THP-1 macrophages. ► Covalent oligomers of ANGPTL4 appear on cell surface and in medium. ► Inactivation of LPL coincide with ANGPTL4 oligomer formation on cell surfaces. -- Abstract: Lipoprotein lipase (LPL) hydrolyzes triglycerides in plasma lipoproteins causing release of fatty acids for metabolic purposes in muscles and adipose tissue. LPL in macrophages in the artery wall may, however, promote foam cell formation and atherosclerosis. Angiopoietin-like protein (ANGPTL) 4 inactivates LPL and ANGPTL4 expression is controlled by peroxisome proliferator-activated receptors (PPAR). The mechanisms for inactivation of LPL by ANGPTL4 was studied in THP-1 macrophages where active LPL is associated with cell surfaces in a heparin-releasable form, while LPL in the culture medium is mostly inactive. The PPARδ agonist GW501516 had no effect on LPL mRNA, but increased ANGPTL4 mRNA and caused a marked reduction of the heparin-releasable LPL activity concomitantly with accumulation of inactive, monomeric LPL in the medium. Intracellular ANGPTL4 was monomeric, while dimers and tetramers of ANGPTL4 were present in the heparin-releasable fraction and medium. GW501516 caused an increase in the amount of ANGPTL4 oligomers on the cell surface that paralleled the decrease in LPL activity. Actinomycin D blocked the effects of GW501516 on ANGPTL4 oligomer formation and prevented the inactivation of LPL. Antibodies against ANGPTL4 interfered with the inactivation of LPL. We conclude that inactivation of LPL in THP-1 macrophages primarily occurs on the cell surface where oligomers of ANGPTL4 are formed.

  19. Structural Transitions of Solvent-Free Oligomer-Grafted Nanoparticles

    KAUST Repository

    Chremos, Alexandros

    2011-09-01

    Novel structural transitions of solvent-free oligomer-grafted nanoparticles are investigated by using molecular dynamics simulations of a coarse-grained bead-spring model. Variations in core size and grafting density lead to self-assembly of the nanoparticles into a variety of distinct structures. At the boundaries between different structures, the nanoparticle systems undergo thermoreversible transitions. This structural behavior, which has not been previously reported, deviates significantly from that of simple liquids. The reversible nature of these transitions in solvent-free conditions offers new ways to control self-assembly of nanoparticles at experimentally accessible conditions. © 2011 American Physical Society.

  20. Expression of enzymes in yeast for lignocellulose derived oligomer CBP

    Science.gov (United States)

    McBride, John E.; Wiswall, Erin; Shikhare, Indraneel; Xu, Haowen; Thorngren, Naomi; Hau, Heidi H.; Stonehouse, Emily

    2017-08-29

    The present invention provides a multi-component enzyme system that hydrolyzes hemicellulose oligomers from hardwood which can be expressed, for example, in yeast such as Saccharomyces cerevisiae. In some embodiments, this invention provides for the engineering of a series of biocatalysts combining the expression and secretion of components of this enzymatic system with robust, rapid xylose utilization, and ethanol fermentation under industrially relevant process conditions for consolidated bioprocessing. In some embodiments, the invention utilizes co-cultures of strains that can achieve significantly improved performance due to the incorporation of additional enzymes in the fermentation system.

  1. Investigation of Membrane Receptors' Oligomers Using Fluorescence Resonance Energy Transfer and Multiphoton Microscopy in Living Cells

    Science.gov (United States)

    Mishra, Ashish K.

    Investigating quaternary structure (oligomerization) of macromolecules (such as proteins and nucleic acids) in living systems (in vivo) has been a great challenge in biophysics, due to molecular diffusion, fluctuations in several biochemical parameters such as pH, quenching of fluorescence by oxygen (when fluorescence methods are used), etc. We studied oligomerization of membrane receptors in living cells by means of Fluorescence (Forster) Resonance Energy Transfer (FRET) using fluorescent markers and two photon excitation fluorescence micro-spectroscopy. Using suitable FRET models, we determined the stoichiometry and quaternary structure of various macromolecular complexes. The proteins of interest for this work are : (1) sigma-1 receptor and (2) rhodopsin, are described as below. (1) Sigma-1 receptors are molecular chaperone proteins, which also regulate ion channels. S1R seems to be involved in substance abuse, as well as several diseases such as Alzheimer's. We studied S1R in the presence and absence of its ligands haloperidol (an antagonist) and pentazocine +/- (an agonist), and found that at low concentration they reside as a mixture of monomers and dimers and that they may form higher order oligomers at higher concentrations. (2) Rhodopsin is a prototypical G protein coupled receptor (GPCR) and is directly involved in vision. GPCRs form a large family of receptors that participate in cell signaling by responding to external stimuli such as drugs, thus being a major drug target (more than 40% drugs target GPCRs). Their oligomerization has been largely controversial. Understanding this may help to understand the functional role of GPCRs oligomerization, and may lead to the discovery of more drugs targeting GPCR oligomers. It may also contribute toward finding a cure for Retinitis Pigmentosa, which is caused by a mutation (G188R) in rhodopsin, a disease which causes blindness and has no cure so far. Comparing healthy rhodopsin's oligomeric structure with that

  2. Conformation of chromatin oligomers. A new argument for a change with the hexanucleosome.

    Science.gov (United States)

    Marion, C; Bezot, P; Hesse-Bezot, C; Roux, B; Bernengo, J C

    1981-11-01

    Quasielastic laser light scattering measurements have been made on chromatin oligomers to obtain information on the transition in their electrooptical properties, previously observed for the hexameric structures [Marion, C. and Roux, B. (1978) Nucleic Acids Res. 5, 4431-4449]. Translational diffusion coefficients were determined for mononucleosomes to octanucleosomes containing histone H1 over a range of ionic strength. At high ionic strength, oligomers show a linear dependence of the logarithm of diffusion coefficient upon the logarithm of number of nucleosomes. At low ionic strength a change occurs between hexamer and heptamer. Our results agree well with the recent sedimentation data of Osipova et al. [Eur. J. Biochem. (1980) 113, 183-188] and of Butler and Thomas [J. Mol. Biol. (1980) 140, 505-529] showing a change in stability with hexamer. Various models for the arrangements of nucleosomes in the superstructure of chromatin are discussed. All calculations clearly indicate a conformational change with the hexanucleosome and the results suggest that, at low ionic strength, the chromatin adopts a loosely helical structure of 28-nm diameter and 22-nm pitch. These results are also consistent with a discontinuity every sixth nucleosome, corresponding to a turn of the helix. This discontinuity may explain the recent electric dichroism data of Lee et al. [Biochemistry (1981) 20, 1438-1445]. The hexanucleosome structure which we have previously suggested, with the faces of nucleosomes arranged radially to the helical axis has been recently confirmed by Mc Ghee et al. [Cell (1980) 22, 87-96]. With an increase of ionic strength, the helix becomes more regular and compact with a slightly reduced outer diameter and a decreased pitch, the dimensions resembling those proposed for solenoid models.

  3. Could Mineral Surfaces have Oriented Amino Acid Polymerization Towards Useful Products?

    Science.gov (United States)

    Lambert, J. F.; Sakhno, Y.; Battistella, A.; Ribetto, B.; Mezzetti, A.; Georgelin, T.; Jaber, M.; Michot, L.

    2017-07-01

    We investigated selective amino acid polymerization on the surface of silicic minerals. Specific amino acid couples were deposited on silica or clays, thermally activated, and the oligomers formed were analyzed. Very different behaviors were observed.

  4. Production of caffeoylmalic acid from glucose in engineered Escherichia coli.

    Science.gov (United States)

    Li, Tianzhen; Zhou, Wei; Bi, Huiping; Zhuang, Yibin; Zhang, Tongcun; Liu, Tao

    2018-07-01

    To achieve biosynthesis of caffeoylmalic acid from glucose in engineered Escherichia coli. We constructed the biosynthetic pathway of caffeoylmalic acid in E. coli by co-expression of heterologous genes RgTAL, HpaBC, At4CL2 and HCT2. To enhance the production of caffeoylmalic acid, we optimized the tyrosine metabolic pathway of E. coli to increase the supply of the substrate caffeic acid. Consequently, an E. coli-E. coli co-culture system was used for the efficient production of caffeoylmalic acid. The final titer of caffeoylmalic acid reached 570.1 mg/L. Microbial production of caffeoylmalic acid using glucose has application potential. In addition, microbial co-culture is an efficient tool for producing caffeic acid esters.

  5. Amyloid oligomer structure characterization from simulations: A general method

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Phuong H., E-mail: phuong.nguyen@ibpc.fr [Laboratoire de Biochimie Théorique, UPR 9080, CNRS Université Denis Diderot, Sorbonne Paris Cité IBPC, 13 rue Pierre et Marie Curie, 75005 Paris (France); Li, Mai Suan [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Derreumaux, Philippe, E-mail: philippe.derreumaux@ibpc.fr [Laboratoire de Biochimie Théorique, UPR 9080, CNRS Université Denis Diderot, Sorbonne Paris Cité IBPC, 13 rue Pierre et Marie Curie, 75005 Paris (France); Institut Universitaire de France, 103 Bvd Saint-Germain, 75005 Paris (France)

    2014-03-07

    Amyloid oligomers and plaques are composed of multiple chemically identical proteins. Therefore, one of the first fundamental problems in the characterization of structures from simulations is the treatment of the degeneracy, i.e., the permutation of the molecules. Second, the intramolecular and intermolecular degrees of freedom of the various molecules must be taken into account. Currently, the well-known dihedral principal component analysis method only considers the intramolecular degrees of freedom, and other methods employing collective variables can only describe intermolecular degrees of freedom at the global level. With this in mind, we propose a general method that identifies all the structures accurately. The basis idea is that the intramolecular and intermolecular states are described in terms of combinations of single-molecule and double-molecule states, respectively, and the overall structures of oligomers are the product basis of the intramolecular and intermolecular states. This way, the degeneracy is automatically avoided. The method is illustrated on the conformational ensemble of the tetramer of the Alzheimer's peptide Aβ{sub 9−40}, resulting from two atomistic molecular dynamics simulations in explicit solvent, each of 200 ns, starting from two distinct structures.

  6. Organization of the resting TCR in nanoscale oligomers.

    Science.gov (United States)

    Schamel, Wolfgang W A; Alarcón, Balbino

    2013-01-01

    Despite the low affinity of the T-cell antigen receptor (TCR) for its peptide/major histocompatibility complex (pMHC) ligand, T cells are very sensitive to their antigens. This paradox can be resolved if we consider that the TCR may be organized into pre-existing oligomers or nanoclusters. Such structures could improve antigen recognition by increasing the functional affinity (avidity) of the TCR-pMHC interaction and by allowing cooperativity between individual TCRs. Up to approximately 20 TCRs become tightly apposed in these nanoclusters, often in a linear manner, and such structures could reflect a relatively generalized phenomenon: the non-random concentration of membrane receptors in specific areas of the plasma membrane known as protein islands. The association of TCRs into nanoclusters can explain the enhanced kinetics of the pMHC-TCR interaction in two dimensional versus three dimensional systems, but also their existence calls for a revision of the TCR triggering models based on pMHC-induced TCR clustering. Interestingly, the B-cell receptor and the FcεRI have also been shown to form nanoclusters, suggesting that the formation of pre-existing receptor oligomers could be widely used in the immune system. © 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  7. Photo-electron spectroscopy study of energy levels in conjugated oligomers

    NARCIS (Netherlands)

    Veenstra, SC; Heeres, A; Stalmach, U; Wildeman, J; Hadziioannou, G; Sawatzky, GA; Jonkman, HT; Moss, SC

    2002-01-01

    We report on the valence orbital structure of poly(para-phenylenevinylene) (PPV)-like oligomers. We studied these molecules as isolated oligomers in the gas phase, as well as in thin films deposited on metal substrates. We use a simple model based on a previously reported Hamiltonian that accurately

  8. Tau oligomers impair memory and induce synaptic and mitochondrial dysfunction in wild-type mice

    Directory of Open Access Journals (Sweden)

    Jackson George R

    2011-06-01

    Full Text Available Abstract Background The correlation between neurofibrillary tangles of tau and disease progression in the brains of Alzheimer's disease (AD patients remains an area of contention. Innovative data are emerging from biochemical, cell-based and transgenic mouse studies that suggest that tau oligomers, a pre-filament form of tau, may be the most toxic and pathologically significant tau aggregate. Results Here we report that oligomers of recombinant full-length human tau protein are neurotoxic in vivo after subcortical stereotaxic injection into mice. Tau oligomers impaired memory consolidation, whereas tau fibrils and monomers did not. Additionally, tau oligomers induced synaptic dysfunction by reducing the levels of synaptic vesicle-associated proteins synaptophysin and septin-11. Tau oligomers produced mitochondrial dysfunction by decreasing the levels of NADH-ubiquinone oxidoreductase (electron transport chain complex I, and activated caspase-9, which is related to the apoptotic mitochondrial pathway. Conclusions This study identifies tau oligomers as an acutely toxic tau species in vivo, and suggests that tau oligomers induce neurodegeneration by affecting mitochondrial and synaptic function, both of which are early hallmarks in AD and other tauopathies. These results open new avenues for neuroprotective intervention strategies of tauopathies by targeting tau oligomers.

  9. Amyloid-β oligomer detection by ELISA in cerebrospinal fluid and brain tissue.

    Science.gov (United States)

    Bruggink, Kim A; Jongbloed, Wesley; Biemans, Elisanne A L M; Veerhuis, Rob; Claassen, Jurgen A H R; Kuiperij, H Bea; Verbeek, Marcel M

    2013-02-15

    Amyloid-β (Aβ) deposits are important pathological hallmarks of Alzheimer's disease (AD). Aβ aggregates into fibrils; however, the intermediate oligomers are believed to be the most neurotoxic species and, therefore, are of great interest as potential biomarkers. Here, we have developed an enzyme-linked immunosorbent assay (ELISA) specific for Aβ oligomers by using the same capture and (labeled) detection antibody. The ELISA predominantly recognizes relatively small oligomers (10-25 kDa) and not monomers. In brain tissue of APP/PS1 transgenic mice, we found that Aβ oligomer levels increase with age. However, for measurements in human samples, pretreatment to remove human anti-mouse antibodies (HAMAs) was required. In HAMA-depleted human hippocampal extracts, the Aβ oligomer concentration was significantly increased in AD compared with nondemented controls. Aβ oligomer levels could also be quantified in pretreated cerebrospinal fluid (CSF) samples; however, no difference was detected between AD and control groups. Our data suggest that levels of small oligomers might not be suitable as biomarkers for AD. In addition, we demonstrate the importance of avoiding HAMA interference in assays to quantify Aβ oligomers in human body fluids. Copyright © 2012 Elsevier Inc. All rights reserved.

  10. Charge Separation and Recombination in Small Band Gap Oligomer-Fullerene Triads

    NARCIS (Netherlands)

    Karsten, Bram P.; Bouwer, Ricardo K. M.; Hummelen, Jan C.; Williams, Rene M.; Janssen, Rene A. J.

    2010-01-01

    Synthesis and photophysics of a series of thiophene-thienopyrazine small band gap oligomers end-capped at both ends with C(60) are presented In these triads a photoinduced electron transfer reaction occurs between the oligomer as a donor and the fullerene as an acceptor Femtosecond photoinduced

  11. Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly.

    Science.gov (United States)

    Iyoda, Masahiko; Hasegawa, Masashi

    2015-01-01

    The construction of redox-active supramolecular assemblies based on star-shaped and radially expanded tetrathiafulvalene (TTF) oligomers with divergent and extended conjugation is summarized. Star-shaped TTF oligomers easily self-aggregate with a nanophase separation to produce supramolecular structures, and their TTF units stack face-to-face to form columnar structures using the fastener effect. Based on redox-active self-organizing supramolecular structures, conducting nanoobjects are constructed by doping of TTF oligomers with oxidants after the formation of such nanostructures. Although radical cations derived from TTF oligomers strongly interact in solution to produce a mixed-valence dimer and π-dimer, it seems to be difficult to produce nanoobjects of radical cations different from those of neutral TTF oligomers. In some cases, however, radical cations form nanostructured fibers and rods by controlling the supramolecular assembly, oxidation states, and counter anions employed.

  12. Amyloid β oligomers in Alzheimer's disease pathogenesis, treatment, and diagnosis.

    Science.gov (United States)

    Viola, Kirsten L; Klein, William L

    2015-02-01

    Protein aggregation is common to dozens of diseases including prionoses, diabetes, Parkinson's and Alzheimer's. Over the past 15 years, there has been a paradigm shift in understanding the structural basis for these proteinopathies. Precedent for this shift has come from investigation of soluble Aβ oligomers (AβOs), toxins now widely regarded as instigating neuron damage leading to Alzheimer's dementia. Toxic AβOs accumulate in AD brain and constitute long-lived alternatives to the disease-defining Aβ fibrils deposited in amyloid plaques. Key experiments using fibril-free AβO solutions demonstrated that while Aβ is essential for memory loss, the fibrillar Aβ in amyloid deposits is not the agent. The AD-like cellular pathologies induced by AβOs suggest their impact provides a unifying mechanism for AD pathogenesis, explaining why early stage disease is specific for memory and accounting for major facets of AD neuropathology. Alternative ideas for triggering mechanisms are being actively investigated. Some research favors insertion of AβOs into membrane, while other evidence supports ligand-like accumulation at particular synapses. Over a dozen candidate toxin receptors have been proposed. AβO binding triggers a redistribution of critical synaptic proteins and induces hyperactivity in metabotropic and ionotropic glutamate receptors. This leads to Ca(2+) overload and instigates major facets of AD neuropathology, including tau hyperphosphorylation, insulin resistance, oxidative stress, and synapse loss. Because different species of AβOs have been identified, a remaining question is which oligomer is the major pathogenic culprit. The possibility has been raised that more than one species plays a role. Despite some key unknowns, the clinical relevance of AβOs has been established, and new studies are beginning to point to co-morbidities such as diabetes and hypercholesterolemia as etiological factors. Because pathogenic AβOs appear early in the disease, they

  13. Radiation-chemical hardening of phenol-formaldehyde oligomers

    International Nuclear Information System (INIS)

    Shlapatskaya, V.V.; Omel'chenko, S.I.

    1978-01-01

    Radiation-chemical hardening of phenol formaldehyde oligomers of the resol type has been studied in the presence of furfural and diallylphthalate diluents. The samples have been hardened on an electron accelerator at an electron energy of 1.0-1.1 MeV and a dose rate of 2-3 Mrad/s. The kinetics of hardening has been studied on the yield of gel fraction within the range of absorbed doses from 7 to 400 Mrad. Radiation-chemical hardening of the studied compositions is activated with sensitizers, namely, amines, metal chlorides, and heterocyclic derivatives of metals. Furfural and diallylphthalate compositions are suitable for forming glass-fibre plastic items by the wet method and coatings under the action of ionizing radiations

  14. Diffusivities and Viscosities of Poly(ethylene oxide) Oligomers

    KAUST Repository

    Hong, Bingbing

    2010-10-14

    Diffusivities and viscosities of poly(ethylene oxide) (PEO) oligomer melts with 1 to 12 repeat units have been obtained from equilibrium molecular dynamics simulations using the TraPPE-UA force field. The simulations generated diffusion coefficients with high accuracy for all of the molar masses studied, but the statistical uncertainties in the viscosity calculations were significantly larger for longer chains. There is good agreement of the calculated viscosities and densities with available experimental data, and thus, the simulations can be used to bridge gaps in the data and for extrapolations with respect to chain length, temperature, and pressure. We explored the convergence characteristics of the Green-Kubo formulas for different chain lengths and propose minimal production times required for convergence of the transport properties. The chain-length dependence of the transport properties suggests that neither Rouse nor reptation models are applicable in the short-chain regime investigated. © 2010 American Chemical Society.

  15. Enhanced lignin monomer production caused by cinnamic Acid and its hydroxylated derivatives inhibits soybean root growth.

    Directory of Open Access Journals (Sweden)

    Rogério Barbosa Lima

    Full Text Available Cinnamic acid and its hydroxylated derivatives (p-coumaric, caffeic, ferulic and sinapic acids are known allelochemicals that affect the seed germination and root growth of many plant species. Recent studies have indicated that the reduction of root growth by these allelochemicals is associated with premature cell wall lignification. We hypothesized that an influx of these compounds into the phenylpropanoid pathway increases the lignin monomer content and reduces the root growth. To confirm this hypothesis, we evaluated the effects of cinnamic, p-coumaric, caffeic, ferulic and sinapic acids on soybean root growth, lignin and the composition of p-hydroxyphenyl (H, guaiacyl (G and syringyl (S monomers. To this end, three-day-old seedlings were cultivated in nutrient solution with or without allelochemical (or selective enzymatic inhibitors of the phenylpropanoid pathway in a growth chamber for 24 h. In general, the results showed that 1 cinnamic, p-coumaric, caffeic and ferulic acids reduced root growth and increased lignin content; 2 cinnamic and p-coumaric acids increased p-hydroxyphenyl (H monomer content, whereas p-coumaric, caffeic and ferulic acids increased guaiacyl (G content, and sinapic acid increased sinapyl (S content; 3 when applied in conjunction with piperonylic acid (PIP, an inhibitor of the cinnamate 4-hydroxylase, C4H, cinnamic acid reduced H, G and S contents; and 4 when applied in conjunction with 3,4-(methylenedioxycinnamic acid (MDCA, an inhibitor of the 4-coumarate:CoA ligase, 4CL, p-coumaric acid reduced H, G and S contents, whereas caffeic, ferulic and sinapic acids reduced G and S contents. These results confirm our hypothesis that exogenously applied allelochemicals are channeled into the phenylpropanoid pathway causing excessive production of lignin and its main monomers. By consequence, an enhanced stiffening of the cell wall restricts soybean root growth.

  16. Amyloid oligomers and protofibrils, but not filaments, self-replicate from native lysozyme.

    Science.gov (United States)

    Mulaj, Mentor; Foley, Joseph; Muschol, Martin

    2014-06-25

    Self-assembly of amyloid fibrils is the molecular mechanism best known for its connection with debilitating human disorders such as Alzheimer's disease but is also associated with various functional cellular responses. There is increasing evidence that amyloid formation proceeds along two distinct assembly pathways involving either globular oligomers and protofibrils or rigid monomeric filaments. Oligomers, in particular, have been implicated as the dominant molecular species responsible for pathogenesis. Yet the molecular mechanisms regulating their self-assembly have remained elusive. Here we show that oligomers/protofibrils and monomeric filaments, formed along distinct assembly pathways, display critical differences in their ability to template amyloid growth at physiological vs denaturing temperatures. At physiological temperatures, amyloid filaments remained stable but could not seed growth of native monomers. In contrast, oligomers and protofibrils not only remained intact but were capable of self-replication using native monomers as the substrate. Kinetic data further suggested that this prion-like growth mode of oligomers/protofibrils involved two distinct activities operating orthogonal from each other: autocatalytic self-replication of oligomers from native monomers and nucleated polymerization of oligomers into protofibrils. The environmental changes to stability and templating competence of these different amyloid species in different environments are likely to be important for understanding the molecular mechanisms underlying both pathogenic and functional amyloid self-assembly.

  17. Labile conjugation of a hydrophilic drug to PLA oligomers to modify a drug delivery system: cephradin in a PLAGA matrix.

    Science.gov (United States)

    Ustariz-Peyret, C; Coudane, J; Vert, M; Kaltsatos, V; Boisramené, B

    2000-01-01

    The physical entrapment of a hydrophilic drug within degradable microspheres is generally difficult because of poor entrapment yield and/or fast release, depending on the microsphere fabrication method. In order to counter the effects of drug hydrophilicity, it is proposed to covalently attach the drug to lactic acid oligomers, with the aim of achieving temporary hydrophobization and slower release controlled by the separation of the drug from the degradable link within the polymer matrix. This strategy was tested on microspheres of the antibiotic cephradin. As the prodrug form, the entrapment of the drug was almost quantitative. The prodrug did degrade in an aqueous medium, modelling body fluids, but cleavage did not occur at the drug-oligomer junction and drug molecules bearing two lactyl residual units were released. When the prodrug is entrapped within a PLAGA matrix, no release was observed within the experimental time period. However, data suggest that conjugation via a bond more sensitive to hydrolysis than the main chain PLA ester bonds should make the system work as desired.

  18. Small protease sensitive oligomers of PrPSc in distinct human prions determine conversion rate of PrP(C.

    Directory of Open Access Journals (Sweden)

    Chae Kim

    Full Text Available The mammalian prions replicate by converting cellular prion protein (PrP(C into pathogenic conformational isoform (PrP(Sc. Variations in prions, which cause different disease phenotypes, are referred to as strains. The mechanism of high-fidelity replication of prion strains in the absence of nucleic acid remains unsolved. We investigated the impact of different conformational characteristics of PrP(Sc on conversion of PrP(C in vitro using PrP(Sc seeds from the most frequent human prion disease worldwide, the Creutzfeldt-Jakob disease (sCJD. The conversion potency of a broad spectrum of distinct sCJD prions was governed by the level, conformation, and stability of small oligomers of the protease-sensitive (s PrP(Sc. The smallest most potent prions present in sCJD brains were composed only of∼20 monomers of PrP(Sc. The tight correlation between conversion potency of small oligomers of human sPrP(Sc observed in vitro and duration of the disease suggests that sPrP(Sc conformers are an important determinant of prion strain characteristics that control the progression rate of the disease.

  19. Direct Correlation Between Ligand-Induced α-Synuclein Oligomers and Amyloid-like Fibril Growth

    DEFF Research Database (Denmark)

    Pedersen, Martin Nors; Foderà, Vito; Horvath, Istvan

    2015-01-01

    link to disease related degenerative activity. Fibrils formed in the presence and absence of FN075 are indistinguishable on microscopic and macroscopic levels. Using small angle X-ray scattering, we reveal that FN075 induced oligomers are similar, but not identical, to oligomers previously observed......Aggregation of proteins into amyloid deposits is the hallmark of several neurodegenerative diseases such as Alzheimer's and Parkinson's disease. The suggestion that intermediate oligomeric species may be cytotoxic has led to intensified investigations of pre-fibrillar oligomers, which...

  20. A combined semiempirical-DFT study of oligomers within the finite-chain approximation, evolution from oligomers to polymers.

    Science.gov (United States)

    Derosa, Pedro A

    2009-06-01

    A computationally cheap approach combining time-independent density functional theory (TIDFT) and semiempirical methods with an appropriate extrapolation procedure is proposed to accurately estimate geometrical and electronic properties of conjugated polymers using just a small set of oligomers. The highest occupied molecular orbital-lowest unoccupied molecular orbital gap (HLG) obtained at a TIDFT level (B3PW91) for two polymers, trans-polyacetylene--the simplest conjugated polymer, and a much larger poly(2-methoxy-5-(2,9-ethyl-hexyloxy)-1,4-phenylenevinylene (MEH-PPV) polymer converge to virtually the same asymptotic value than the excitation energy obtained with time-dependent DFT (TDDFT) calculations using the same functional. For TIDFT geometries, the HLG is found to converge to a value within the experimentally accepted range for the band gap of these polymers, when an exponential extrapolation is used; however if semiempirical geometries are used, a linear fit of the HLG versus 1/n is found to produce the best results. Geometrical parameters are observed to reach a saturation value in good agreement with experimental information, within the length of oligomers calculated here and no extrapolation was considered necessary. Finally, the performance of three different semiempirical methods (AM1, PM3, and MNDO) and for the TIDFT calculations, the performance of 7 different full electron basis sets (6-311+G**, 6-31+ +G**, 6-311+ +G**, 6-31+G**, 6-31G**, 6-31+G*, and 6-31G) is compared and it is determined that the choice of semiempirical method or the basis set does not significantly affect the results. 2008 Wiley Periodicals, Inc.

  1. Supplementation with xylanase and β-xylosidase to reduce xylo-oligomer and xylan inhibition of enzymatic hydrolysis of cellulose and pretreated corn stover

    Science.gov (United States)

    2011-01-01

    Background Hemicellulose is often credited with being one of the important physical barriers to enzymatic hydrolysis of cellulose, and acts by blocking enzyme access to the cellulose surface. In addition, our recent research has suggested that hemicelluloses, particularly in the form of xylan and its oligomers, can more strongly inhibit cellulase activity than do glucose and cellobiose. Removal of hemicelluloses or elimination of their negative effects can therefore become especially pivotal to achieving higher cellulose conversion with lower enzyme doses. Results In this study, cellulase was supplemented with xylanase and β-xylosidase to boost conversion of both cellulose and hemicellulose in pretreated biomass through conversion of xylan and xylo-oligomers to the less inhibitory xylose. Although addition of xylanase and β-xylosidase did not necessarily enhance Avicel hydrolysis, glucan conversions increased by 27% and 8% for corn stover pretreated with ammonia fiber expansion (AFEX) and dilute acid, respectively. In addition, adding hemicellulase several hours before adding cellulase was more beneficial than later addition, possibly as a result of a higher adsorption affinity of cellulase and xylanase to xylan than glucan. Conclusions This key finding elucidates a possible mechanism for cellulase inhibition by xylan and xylo-oligomers and emphasizes the need to optimize the enzyme formulation for each pretreated substrate. More research is needed to identify advanced enzyme systems designed to hydrolyze different substrates with maximum overall enzyme efficacy. PMID:21702938

  2. Supplementation with xylanase and β-xylosidase to reduce xylo-oligomer and xylan inhibition of enzymatic hydrolysis of cellulose and pretreated corn stover

    Directory of Open Access Journals (Sweden)

    Qing Qing

    2011-06-01

    Full Text Available Abstract Background Hemicellulose is often credited with being one of the important physical barriers to enzymatic hydrolysis of cellulose, and acts by blocking enzyme access to the cellulose surface. In addition, our recent research has suggested that hemicelluloses, particularly in the form of xylan and its oligomers, can more strongly inhibit cellulase activity than do glucose and cellobiose. Removal of hemicelluloses or elimination of their negative effects can therefore become especially pivotal to achieving higher cellulose conversion with lower enzyme doses. Results In this study, cellulase was supplemented with xylanase and β-xylosidase to boost conversion of both cellulose and hemicellulose in pretreated biomass through conversion of xylan and xylo-oligomers to the less inhibitory xylose. Although addition of xylanase and β-xylosidase did not necessarily enhance Avicel hydrolysis, glucan conversions increased by 27% and 8% for corn stover pretreated with ammonia fiber expansion (AFEX and dilute acid, respectively. In addition, adding hemicellulase several hours before adding cellulase was more beneficial than later addition, possibly as a result of a higher adsorption affinity of cellulase and xylanase to xylan than glucan. Conclusions This key finding elucidates a possible mechanism for cellulase inhibition by xylan and xylo-oligomers and emphasizes the need to optimize the enzyme formulation for each pretreated substrate. More research is needed to identify advanced enzyme systems designed to hydrolyze different substrates with maximum overall enzyme efficacy.

  3. Dynamic conformations of nucleophosmin (NPM1 at a key monomer-monomer interface affect oligomer stability and interactions with granzyme B.

    Directory of Open Access Journals (Sweden)

    Wei D Duan-Porter

    Full Text Available Nucleophosmin (NPM1 is an abundant, nucleolar tumor antigen with important roles in cell proliferation and putative contributions to oncogenesis. Wild-type NPM1 forms pentameric oligomers through interactions at the amino-terminal core domain. A truncated form of NPM1 found in some hepatocellular carcinoma tissue formed an unusually stable oligomer and showed increased susceptibility to cleavage by granzyme B. Initiation of translation at the seventh methionine generated a protein (M7-NPM that shared all these properties. We used deuterium exchange mass spectrometry (DXMS to perform a detailed structural analysis of wild-type NPM1 and M7-NPM, and found dynamic conformational shifts or local "unfolding" at a specific monomer-monomer interface which included the β-hairpin "latch." We tested the importance of interactions at the β-hairpin "latch" by replacing a conserved tyrosine in the middle of the β-hairpin loop with glutamic acid, generating Y67E-NPM. Y67E-NPM did not form stable oligomers and further, prevented wild-type NPM1 oligomerization in a dominant-negative fashion, supporting the critical role of the β-hairpin "latch" in monomer-monomer interactions. Also, we show preferential cleavage by granzyme B at one of two available aspartates (either D161 or D122 in M7-NPM and Y67E-NPM, whereas wild-type NPM1 was cleaved at both sites. Thus, we observed a correlation between the propensity to form oligomers and granzyme B cleavage site selection in nucleophosmin proteins, suggesting that a small change at an important monomer-monomer interface can affect conformational shifts and impact protein-protein interactions.

  4. Dietary flavanols and procyanidin oligomers from cocoa (Theobroma cacao) inhibit platelet function.

    Science.gov (United States)

    Murphy, Karen J; Chronopoulos, Andriana K; Singh, Indu; Francis, Maureen A; Moriarty, Helen; Pike, Marilyn J; Turner, Alan H; Mann, Neil J; Sinclair, Andrew J

    2003-06-01

    Flavonoids may be partly responsible for some health benefits, including antiinflammatory action and a decreased tendency for the blood to clot. An acute dose of flavanols and oligomeric procyanidins from cocoa powder inhibits platelet activation and function over 6 h in humans. This study sought to evaluate whether 28 d of supplementation with cocoa flavanols and related procyanidin oligomers would modulate human platelet reactivity and primary hemostasis and reduce oxidative markers in vivo. Thirty-two healthy subjects were assigned to consume active (234 mg cocoa flavanols and procyanidins/d) or placebo (cocoa flavanols and procyanidins/d) tablets in a blinded parallel-designed study. Platelet function was determined by measuring platelet aggregation, ATP release, and expression of activation-dependent platelet antigens by using flow cytometry. Plasma was analyzed for oxidation markers and antioxidant status. Plasma concentrations of epicatechin and catechin in the active group increased by 81% and 28%, respectively, during the intervention period. The active group had significantly lower P selectin expression and significantly lower ADP-induced aggregation and collagen-induced aggregation than did the placebo group. Plasma ascorbic acid concentrations were significantly higher in the active than in the placebo group (P antioxidant status did not change in either group. Cocoa flavanol and procyanidin supplementation for 28 d significantly increased plasma epicatechin and catechin concentrations and significantly decreased platelet function. These data support the results of acute studies that used higher doses of cocoa flavanols and procyanidins.

  5. Chemical modifications of antisense morpholino oligomers enhance their efficacy against Ebola virus infection.

    Science.gov (United States)

    Swenson, Dana L; Warfield, Kelly L; Warren, Travis K; Lovejoy, Candace; Hassinger, Jed N; Ruthel, Gordon; Blouch, Robert E; Moulton, Hong M; Weller, Dwight D; Iversen, Patrick L; Bavari, Sina

    2009-05-01

    Phosphorodiamidate morpholino oligomers (PMOs) are uncharged nucleic acid-like molecules designed to inactivate the expression of specific genes via the antisense-based steric hindrance of mRNA translation. PMOs have been successful at knocking out viral gene expression and replication in the case of acute viral infections in animal models and have been well tolerated in human clinical trials. We propose that antisense PMOs represent a promising class of therapeutic agents that may be useful for combating filoviral infections. We have previously shown that mice treated with a PMO whose sequence is complementary to a region spanning the start codon of VP24 mRNA were protected against lethal Ebola virus challenge. In the present study, we report on the abilities of two additional VP24-specific PMOs to reduce the cell-free translation of a VP24 reporter, to inhibit the in vitro replication of Ebola virus, and to protect mice against lethal challenge when the PMOs are delivered prior to infection. Additionally, structure-activity relationship evaluations were conducted to assess the enhancement of antiviral efficacy associated with PMO chemical modifications that included conjugation with peptides of various lengths and compositions, positioning of conjugated peptides to either the 5' or the 3' terminus, and the conferring of charge modifications by the addition of piperazine moieties. Conjugation with arginine-rich peptides greatly enhanced the antiviral efficacy of VP24-specific PMOs in infected cells and mice during lethal Ebola virus challenge.

  6. Atomistic simulation of CO 2 solubility in poly(ethylene oxide) oligomers

    KAUST Repository

    Hong, Bingbing; Panagiotopoulos, Athanassios Z.

    2013-01-01

    We have performed atomistic molecular dynamics simulations coupled with thermodynamic integration to obtain the excess chemical potential and pressure-composition phase diagrams for CO2 in poly(ethylene oxide) oligomers. Poly(ethylene oxide

  7. Molecular Dynamics Simulations of Silica Nanoparticles Grafted with Poly(ethylene oxide) Oligomer Chains

    KAUST Repository

    Hong, Bingbing; Panagiotopoulos, Athanassios Z.

    2012-01-01

    A molecular model of silica nanoparticles grafted with poly(ethylene oxide) oligomers has been developed for predicting the transport properties of nanoparticle organic-hybrid materials (NOHMs). Ungrafted silica nanoparticles in a medium of poly(ethylene

  8. Hydrogen bonding as the origin of the switching behavior in dithiolated phenylene-vinylene oligomers

    KAUST Repository

    Obodo, Tobechukwu Joshua; Gkionis, Konstantinos; Rungger, Ivan; Sanvito, Stefano; Schwingenschlö gl, Udo

    2013-01-01

    We investigate theoretically the switching behavior of a dithiolated phenylene-vinylene oligomer sandwiched between Au(111) electrodes using self-interaction corrected density-functional theory combined with the nonequilibrium Green

  9. Acrylate oligomers in ultraviolet cured PSA's glass transition, molecular weight versus peel strength

    International Nuclear Information System (INIS)

    Miller, H.C.

    1999-01-01

    Typically those not skilled in the art relate Glass Transition Temperature to Pressure Sensitive Adhesives. You need a low Tg material to prepare good pressure sensitive adhesives. This report deals with a wide range acrylate terminated oligomers in a standard formulation. Molecular weight, chemical structure variations are examined versus the Glass Transition of the oligomers and final peel strength. Each formulated adhesive will require unique oligomer properties to reach one hundred newtons per 100 millimeters (5.71 pounds per square inch) peel strength. Excellent peel strengths may be obtained with oligomer molecular weight ranging from six thousand to one thousand molecular weight and glass transition temperatures ranging from minus seventy four degrees centigrade up to thirteen degrees centigrade

  10. Charge transport and dielectric relaxation processes in anilin-based oligomers

    Czech Academy of Sciences Publication Activity Database

    Mrlík, M.; Moučka, R.; Ilčíková, M.; Bober, Patrycja; Kazantseva, N.; Špitálský, Z.; Trchová, Miroslava; Stejskal, Jaroslav

    2014-01-01

    Roč. 192, June (2014), s. 37-42 ISSN 0379-6779 Institutional support: RVO:61389013 Keywords : aniline-based oligomers * conductivity * dielectric properties Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.252, year: 2014

  11. Computer simulations and theoretical aspects of the depletion interaction in protein-oligomer mixtures.

    Science.gov (United States)

    Boncina, M; Rescic, J; Kalyuzhnyi, Yu V; Vlachy, V

    2007-07-21

    The depletion interaction between proteins caused by addition of either uncharged or partially charged oligomers was studied using the canonical Monte Carlo simulation technique and the integral equation theory. A protein molecule was modeled in two different ways: either as (i) a hard sphere of diameter 30.0 A with net charge 0, or +5, or (ii) as a hard sphere with discrete charges (depending on the pH of solution) of diameter 45.4 A. The oligomers were pictured as tangentially jointed, uncharged, or partially charged, hard spheres. The ions of a simple electrolyte present in solution were represented by charged hard spheres distributed in the dielectric continuum. In this study we were particularly interested in changes of the protein-protein pair-distribution function, caused by addition of the oligomer component. In agreement with previous studies we found that addition of a nonadsorbing oligomer reduces the phase stability of solution, which is reflected in the shape of the protein-protein pair-distribution function. The value of this function in protein-protein contact increases with increasing oligomer concentration, and is larger for charged oligomers. The range of the depletion interaction and its strength also depend on the length (number of monomer units) of the oligomer chain. The integral equation theory, based on the Wertheim Ornstein-Zernike approach applied in this study, was found to be in fair agreement with Monte Carlo results only for very short oligomers. The computer simulations for a model mimicking the lysozyme molecule (ii) are in qualitative agreement with small-angle neutron experiments for lysozyme-dextran mixtures.

  12. Structure and properties of binary polystyrene-epoxy acrylate oligomer mixtures irradiated by electron beams

    International Nuclear Information System (INIS)

    Lomonosova, N.V.

    1995-01-01

    The change in the structure of oriented polymer-oligomer systems based on polystyrene (PS) with M > 10 6 and epoxy acrylate oligomers (aliphatic and aromatic) under irradiation by accelerated electrons was studied using birefringence, isometric heating, IR dichroism, and thermooptical analysis. Mechanical properties of these systems were investigated. It was found that, by adding aliphatic epoxy acrylate to PS and further irradiating this mixture, one can obtain both isotropic and oriented composites with higher strengths, elasticity moduli, and glass transition temperatures

  13. Laser-Induced Population Inversion in Rhodamine 6G for Lysozyme Oligomer Detection.

    Science.gov (United States)

    Hanczyc, Piotr; Sznitko, Lech

    2017-06-06

    Fluorescence spectroscopy is a common method for detecting amyloid fibrils in which organic fluorophores are used as markers that exhibit an increase in quantum yield upon binding. However, most of the dyes exhibit enhanced emission only when bound to mature fibrils, and significantly weaker signals are obtained in the presence of amyloid oligomers. In the concept of population inversion, a laser is used as an excitation source to keep the major fraction of molecules in the excited state to create the pathways for the occurrence of stimulated emission. In the case of the proteins, the conformational changes lead to the self-ordering and thus different light scattering conditions that can influence the optical signatures of the generated light. Using this methodology, we show it is possible to optically detect amyloid oligomers using commonly available staining dyes in which population inversion can be induced. The results indicate that rhodamine 6G molecules are complexed with oligomers, and using a laser-assisted methodology, weakly emissive states can be detected. Significant spectral red-shifting of rhodamine 6G dispersed with amyloid oligomers and a notable difference determined by comparison of spectra of the fibrils suggest the existence of specific dye aggregates around the oligomer binding sites. This approach can provide new insights into intermediate oligomer states that are believed to be responsible for toxic seeding in neurodegeneration diseases.

  14. Donor-acceptor-donor thienyl/bithienyl-benzothiadiazole/quinoxaline model oligomers: experimental and theoretical studies.

    Science.gov (United States)

    Pina, João; de Melo, J Seixas; Breusov, D; Scherf, Ullrich

    2013-09-28

    A comprehensive spectral and photophysical investigation of four donor-acceptor-donor (DAD) oligomers consisting of electron-deficient 2,1,3-benzothiadiazole or quinoxaline moieties linked to electron-rich thienyl or bithienyl units has been undertaken. Additionally, a bis(dithienyl) substituted naphthalene was also investigated. The D-A-D nature of these oligomers resulted in the presence of an intramolecular charge transfer (ICT) state, which was further substantiated by solvatochromism studies (analysis with the Lippert-Mataga formalism). Hereby, significant differences have been obtained for the fluorescence quantum yields of the oligomers in the non-polar solvent methylcyclohexane vs. the polar ethanol. The study was further complemented with the determination of the optimized ground-state molecular geometries for the oligomers together with the prediction of the lowest vertical one-electron excitation energy and the relevant molecular orbital contours using DFT calculations. The electronic transitions show a clear HOMO to LUMO charge-transfer character. In contrast to the thiophene oligomers (the oligothiophenes with n = 1-7), where the intersystem crossing (ISC) yield decreases with n, the studied DAD oligomers were found to show an increase in the ISC efficiency with the number of (donor) thienyl units.

  15. Supercritical fluid assisted production of chitosan oligomers micrometric powders.

    Science.gov (United States)

    Du, Zhe; Shen, Yu-Bin; Tang, Chuan; Guan, Yi-Xin; Yao, Shan-Jing; Zhu, Zi-Qiang

    2014-02-15

    Chitosan oligomers (O-chitosan) micrometric particles were produced from aqueous solution using a novel process, i.e. supercritical fluid assisted atomization introduced by hydrodynamic cavitation mixer (SAA-HCM). Hydrodynamic cavitation was introduced to enhance mass transfer and facilitate the mixing between SC-CO2 and liquid solution for fine particles formation. Well defined, separated and spherical microparticles were obtained, and the particles size could be well controlled with narrow distribution ranging from 0.5 μm to 3 μm. XRD patterns showed amorphous structure of O-chitosan microparticles. FTIR, TGA and DSC analyses confirmed that no change in molecular structure and thermal stability after SAA-HCM processing, while the water content was between 5.8% and 8.4%. Finally, tap densities were determined to be below 0.45 g/cm(3) indicating hollow or porous structures of microparticles. By tuning process parameters, theoretical mass median aerodynamic sizes lied inside respirable range of 1-2 μm, which presented the potential of the O-chitosan microparticles in application as inhaled dry powders. SAA-HCM was demonstrated to be very useful in particle size engineering. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Dopamine induces soluble α-synuclein oligomers and nigrostriatal degeneration.

    Science.gov (United States)

    Mor, Danielle E; Tsika, Elpida; Mazzulli, Joseph R; Gould, Neal S; Kim, Hanna; Daniels, Malcolm J; Doshi, Shachee; Gupta, Preetika; Grossman, Jennifer L; Tan, Victor X; Kalb, Robert G; Caldwell, Kim A; Caldwell, Guy A; Wolfe, John H; Ischiropoulos, Harry

    2017-11-01

    Parkinson's disease (PD) is defined by the loss of dopaminergic neurons in the substantia nigra and the formation of Lewy body inclusions containing aggregated α-synuclein. Efforts to explain dopamine neuron vulnerability are hindered by the lack of dopaminergic cell death in α-synuclein transgenic mice. To address this, we manipulated both dopamine levels and α-synuclein expression. Nigrally targeted expression of mutant tyrosine hydroxylase with enhanced catalytic activity increased dopamine levels without damaging neurons in non-transgenic mice. In contrast, raising dopamine levels in mice expressing human A53T mutant α-synuclein induced progressive nigrostriatal degeneration and reduced locomotion. Dopamine elevation in A53T mice increased levels of potentially toxic α-synuclein oligomers, resulting in conformationally and functionally modified species. Moreover, in genetically tractable Caenorhabditis elegans models, expression of α-synuclein mutated at the site of interaction with dopamine prevented dopamine-induced toxicity. These data suggest that a unique mechanism links two cardinal features of PD: dopaminergic cell death and α-synuclein aggregation.

  17. The hunt for brain Aβ oligomers by peripherally circulating multi-functional nanoparticles: Potential therapeutic approach for Alzheimer disease.

    Science.gov (United States)

    Mancini, Simona; Minniti, Stefania; Gregori, Maria; Sancini, Giulio; Cagnotto, Alfredo; Couraud, Pierre-Olivier; Ordóñez-Gutiérrez, Lara; Wandosell, Francisco; Salmona, Mario; Re, Francesca

    2016-01-01

    We previously showed the ability of liposomes bi-functionalized with phosphatidic acid and an ApoE-derived peptide (mApoE-PA-LIP) to reduce brain Aβ in transgenic Alzheimer mice. Herein we investigated the efficacy of mApoE-PA-LIP to withdraw Aβ peptide in different aggregation forms from the brain, using a transwell cellular model of the blood-brain barrier and APP/PS1 mice. The spontaneous efflux of Aβ oligomers (Aβo), but not of Aβ fibrils, from the 'brain' side of the transwell was strongly enhanced (5-fold) in presence of mApoE-PA-LIP in the 'blood' compartment. This effect is due to a withdrawal of Aβo exerted by peripheral mApoE-PA-LIP by sink effect, because, when present in the brain side, they did not act as Aβo carrier and limit the oligomer efflux. In vivo peripheral administration of mApoE-PA-LIP significantly increased the plasma Aβ level, suggesting that Aβ-binding particles exploiting the sink effect can be used as a therapeutic strategy for Alzheimer disease. From the Clinical Editor: Alzheimer disease (AD) at present is an incurable disease, which is thought to be caused by an accumulation of amyloid-β (Aβ) peptides in the brain. Many strategies in combating this disease have been focused on either the prevention or dissolving these peptides. In this article, the authors showed the ability of liposomes bi-functionalized with phosphatidic acid and with an ApoE- derived peptide to withdraw amyloid peptides from the brain. The data would help the future design of more novel treatment for Alzheimer disease. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Antiproliferative and apoptotic effects of selective phenolic acids on T47D human breast cancer cells: potential mechanisms of action

    International Nuclear Information System (INIS)

    Kampa, Marilena; Boskou, Dimitrios; Gravanis, Achille; Castanas, Elias; Alexaki, Vassilia-Ismini; Notas, George; Nifli, Artemissia-Phoebe; Nistikaki, Anastassia; Hatzoglou, Anastassia; Bakogeorgou, Efstathia; Kouimtzoglou, Elena; Blekas, George

    2004-01-01

    The oncoprotective role of food-derived polyphenol antioxidants has been described but the implicated mechanisms are not yet clear. In addition to polyphenols, phenolic acids, found at high concentrations in a number of plants, possess antioxidant action. The main phenolic acids found in foods are derivatives of 4-hydroxybenzoic acid and 4-hydroxycinnamic acid. This work concentrates on the antiproliferative action of caffeic acid, syringic acid, sinapic acid, protocatechuic acid, ferulic acid and 3,4-dihydroxy-phenylacetic acid (PAA) on T47D human breast cancer cells, testing their antioxidant activity and a number of possible mechanisms involved (interaction with membrane and intracellular receptors, nitric oxide production). The tested compounds showed a time-dependent and dose-dependent inhibitory effect on cell growth with the following potency: caffeic acid > ferulic acid = protocatechuic acid = PAA > sinapic acid = syringic acid. Caffeic acid and PAA were chosen for further analysis. The antioxidative activity of these phenolic acids in T47D cells does not coincide with their inhibitory effect on tumoral proliferation. No interaction was found with steroid and adrenergic receptors. PAA induced an inhibition of nitric oxide synthase, while caffeic acid competes for binding and results in an inhibition of aryl hydrocarbon receptor-induced CYP1A1 enzyme. Both agents induce apoptosis via the Fas/FasL system. Phenolic acids exert a direct antiproliferative action, evident at low concentrations, comparable with those found in biological fluids after ingestion of foods rich in phenolic acids. Furthermore, the direct interaction with the aryl hydrocarbon receptor, the nitric oxide synthase inhibition and their pro-apoptotic effect provide some insights into their biological mode of action

  19. Solvent free low-melt viscosity imide oligomers and thermosetting polymide composites

    Science.gov (United States)

    Chuang, Chun-Hua (Inventor)

    2012-01-01

    .[.This invention relates to the composition and a solvent-free process for preparing novel imide oligomers and polymers specifically formulated with effective amounts of a dianhydride such as 2,3,3',4-biphenyltetra carboxylic dianydride (a-BPDA), at least one aromatic diamine and an endcapped of 4-phenylethynylphthalic anhydride (PEPA) or nadic anhydride to produce imide oligomers that possess a low-melt viscosity of 1-60 poise at 260-280.degree. C. When the imide oligomer melt is cured at about 371.degree. C. in a press or autoclave under 100-500 psi, the melt resulted in a thermoset polyimide having a glass transition temperature (T.sub.g) equal to and above 310.degree. C. A novel feature of this process is that the monomers; namely the dianhydrides, diamines and the endcaps, are melt processable to form imide oligomers at temperatures ranging between 232-280.degree. C. (450-535.degree. F.) without any solvent. These low-melt imide oligomers can be easily processed by resin transfer molding (RTM), vacuum-assisted resin transfer molding (VARTM) or the resin infusion process with fiber preforms e.g. carbon, glass or quartz preforms to produce polyimide matrix composites with 288-343.degree. C. (550-650.degree. F.) high temperature performance capability..]. .Iadd.This invention relates to compositions and a solvent-free reaction process for preparing imide oligomers and polymers specifically derived from effective amounts of dianhydrides such as 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), at least one aromatic polyamine and an end-cap such as 4-phenylethynyphthalic anhydride (PEPA) or nadic anhydride to produce imide oligomers that possess a low-melt viscosity of 1-60 poise at 260.degree. C.-280.degree. C..Iaddend.

  20. Separation of xylose oligomers using centrifugal partition chromatography with a butanol-methanol-water system.

    Science.gov (United States)

    Lau, Ching-Shuan; Clausen, Edgar C; Lay, Jackson O; Gidden, Jennifer; Carrier, Danielle Julie

    2013-01-01

    Xylose oligomers are the intermediate products of xylan depolymerization into xylose monomers. An understanding of xylan depolymerization kinetics is important to improve the conversion of xylan into monomeric xylose and to minimize the formation of inhibitory products, thereby reducing ethanol production costs. The study of xylan depolymerization requires copious amount of xylose oligomers, which are expensive if acquired commercially. Our approach consisted of producing in-house oligomer material. To this end, birchwood xylan was used as the starting material and hydrolyzed in hot water at 200 °C for 60 min with a 4 % solids loading. The mixture of xylose oligomers was subsequently fractionated by a centrifugal partition chromatography (CPC) with a solvent system of butanol:methanol:water in a 5:1:4 volumetric ratio. Operating in an ascending mode, the butanol-rich upper phase (the mobile phase) eluted xylose oligomers from the water-rich stationary phase at a 4.89 mL/min flow rate for a total fractionation time of 300 min. The elution of xylose oligomers occurred between 110 and 280 min. The yields and purities of xylobiose (DP 2), xylotriose (DP 3), xylotetraose (DP 4), and xylopentaose (DP 5) were 21, 10, 14, and 15 mg/g xylan and 95, 90, 89, and 68 %, respectively. The purities of xylose oligomers from this solvent system were higher than those reported previously using tetrahydrofuran:dimethyl sulfoxide:water in a 6:1:3 volumetric ratio. Moreover, the butanol-based solvent system improved overall procedures by facilitating the evaporation of the solvents from the CPC fractions, rendering the purification process more efficient.

  1. Biomaterials made of bile acids

    Institute of Scientific and Technical Information of China (English)

    ZHANG JiaWei; ZHU XiaoXia

    2009-01-01

    The use of natural compounds in the preparation of new materials can improve the biocompatibility of the materials and avoid any potential toxicity of the degradation products when used for biomedical applications.Bile acids are amphiphilic molecules biosynthesized in the liver.They are used to prepare various polymers and oligomers.These polymers made of bile acids are promising materials in both biomedical and pharmaceutical fields.

  2. Biomaterials made of bile acids

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The use of natural compounds in the preparation of new materials can improve the biocompatibility of the materials and avoid any potential toxicity of the degradation products when used for biomedical applications. Bile acids are amphiphilic molecules biosynthesized in the liver. They are used to prepare various polymers and oligomers. These polymers made of bile acids are promising materials in both biomedical and pharmaceutical fields.

  3. Mitochondrial Ca2+ overload underlies Abeta oligomers neurotoxicity providing an unexpected mechanism of neuroprotection by NSAIDs.

    Science.gov (United States)

    Sanz-Blasco, Sara; Valero, Ruth A; Rodríguez-Crespo, Ignacio; Villalobos, Carlos; Núñez, Lucía

    2008-07-23

    Dysregulation of intracellular Ca(2+) homeostasis may underlie amyloid beta peptide (Abeta) toxicity in Alzheimer's Disease (AD) but the mechanism is unknown. In search for this mechanism we found that Abeta(1-42) oligomers, the assembly state correlating best with cognitive decline in AD, but not Abeta fibrils, induce a massive entry of Ca(2+) in neurons and promote mitochondrial Ca(2+) overload as shown by bioluminescence imaging of targeted aequorin in individual neurons. Abeta oligomers induce also mitochondrial permeability transition, cytochrome c release, apoptosis and cell death. Mitochondrial depolarization prevents mitochondrial Ca(2+) overload, cytochrome c release and cell death. In addition, we found that a series of non-steroidal anti-inflammatory drugs (NSAIDs) including salicylate, sulindac sulfide, indomethacin, ibuprofen and R-flurbiprofen depolarize mitochondria and inhibit mitochondrial Ca(2+) overload, cytochrome c release and cell death induced by Abeta oligomers. Our results indicate that i) mitochondrial Ca(2+) overload underlies the neurotoxicity induced by Abeta oligomers and ii) inhibition of mitochondrial Ca(2+) overload provides a novel mechanism of neuroprotection by NSAIDs against Abeta oligomers and AD.

  4. Mitochondrial Ca2+ overload underlies Abeta oligomers neurotoxicity providing an unexpected mechanism of neuroprotection by NSAIDs.

    Directory of Open Access Journals (Sweden)

    Sara Sanz-Blasco

    Full Text Available Dysregulation of intracellular Ca(2+ homeostasis may underlie amyloid beta peptide (Abeta toxicity in Alzheimer's Disease (AD but the mechanism is unknown. In search for this mechanism we found that Abeta(1-42 oligomers, the assembly state correlating best with cognitive decline in AD, but not Abeta fibrils, induce a massive entry of Ca(2+ in neurons and promote mitochondrial Ca(2+ overload as shown by bioluminescence imaging of targeted aequorin in individual neurons. Abeta oligomers induce also mitochondrial permeability transition, cytochrome c release, apoptosis and cell death. Mitochondrial depolarization prevents mitochondrial Ca(2+ overload, cytochrome c release and cell death. In addition, we found that a series of non-steroidal anti-inflammatory drugs (NSAIDs including salicylate, sulindac sulfide, indomethacin, ibuprofen and R-flurbiprofen depolarize mitochondria and inhibit mitochondrial Ca(2+ overload, cytochrome c release and cell death induced by Abeta oligomers. Our results indicate that i mitochondrial Ca(2+ overload underlies the neurotoxicity induced by Abeta oligomers and ii inhibition of mitochondrial Ca(2+ overload provides a novel mechanism of neuroprotection by NSAIDs against Abeta oligomers and AD.

  5. Solvent Free Low-Melt Viscosity Imide Oligomers And Thermosetting Polyimide Composites

    Science.gov (United States)

    Chuang, CHun-Hua (Inventor)

    2006-01-01

    This invention relates to the composition and a solvent-free process for preparing novel imide oligomers and polymers specifically formulated with effective amounts of a dianhydride such as 2,3,3',4-biphenyltetra carboxylic dianydride (a-BPDA), at least one aromatic diamine' and an endcapped of 4-phenylethynylphthalic anhydride (PEPA) or nadic anhydride to produce imide oligomers that possess a low-melt viscosity of 1-60 poise at 260-280" C. When the imide oligomer melt is cured at about 371 C. in a press or autoclave under 100-500 psi, the melt resulted in a thermoset polyimide having a glass transition temperature (T(sub g)) equal to and above 310 C. A novel feature of this process is that the monomers; namely the dianhydrides, diamines and the endcaps, are melt processable to form imide oligomers at temperatures ranging between 232-280 C. (450-535 F) without any solvent. These low-melt imide oligomers can be easily processed by resin transfer molding (RTM), vacuum-assisted resin transfer molding (VARTM) or the resin infusion process with fiber preforms e.g. carbon, glass or quartz preforms to produce polyimide matrix composites with 288-343C (550-650 F) high temperature performance capability.

  6. Extracellular Tau Oligomers Induce Invasion of Endogenous Tau into the Somatodendritic Compartment and Axonal Transport Dysfunction

    Science.gov (United States)

    Swanson, Eric; Breckenridge, Leigham; McMahon, Lloyd; Som, Sreemoyee; McConnell, Ian; Bloom, George S.

    2017-01-01

    Aggregates composed of the microtubule associated protein, tau, are a hallmark of Alzheimer’s disease and non-Alzheimer’s tauopathies. Extracellular tau can induce the accumulation and aggregation of intracellular tau, and tau pathology can be transmitted along neural networks over time. There are six splice variants of central nervous system tau, and various oligomeric and fibrillar forms are associated with neurodegeneration in vivo. The particular extracellular forms of tau capable of transferring tau pathology from neuron to neuron remain ill defined, however, as do the consequences of intracellular tau aggregation on neuronal physiology. The present study was undertaken to compare the effects of extracellular tau monomers, oligomers, and filaments comprising various tau isoforms on the behavior of cultured neurons. We found that 2N4R or 2N3R tau oligomers provoked aggregation of endogenous intracellular tau much more effectively than monomers or fibrils, or of oligomers made from other tau isoforms, and that a mixture of all six isoforms most potently provoked intracellular tau accumulation. These effects were associated with invasion of tau into the somatodendritic compartment. Finally, we observed that 2N4R oligomers perturbed fast axonal transport of membranous organelles along microtubules. Intracellular tau accumulation was often accompanied by increases in the run length, run time and instantaneous velocity of membranous cargo. This work indicates that extracellular tau oligomers can disrupt normal neuronal homeostasis by triggering axonal tau accumulation and loss of the polarized distribution of tau, and by impairing fast axonal transport. PMID:28482642

  7. Antioxidant Activity of Hispidin Oligomers from Medicinal Fungi: A DFT Study

    Directory of Open Access Journals (Sweden)

    El Hassane Anouar

    2014-03-01

    Full Text Available Hispidin oligomers are styrylpyrone pigments isolated from the medicinal fungi Inonotus xeranticus and Phellinus linteus. They exhibit diverse biological activities and strong free radical scavenging activity. To rationalize the antioxidant activity of a series of four hispidin oligomers and determine the favored mechanism involved in free radical scavenging, DFT calculations were carried out at the B3P86/6-31+G (d, p level of theory in gas and solvent. The results showed that bond dissociation enthalpies of OH groups of hispidin oligomers (ArOH and spin density delocalization of related radicals (ArO• are the appropriate parameters to clarify the differences between the observed antioxidant activities for the four oligomers. The effect of the number of hydroxyl groups and presence of a catechol moiety conjugated to a double bond on the antioxidant activity were determined. Thermodynamic and kinetic studies showed that the PC-ET mechanism is the main mechanism involved in free radical scavenging. The spin density distribution over phenoxyl radicals allows a better understanding of the hispidin oligomers formation.

  8. Alzheimer's-associated Aβ oligomers show altered structure, immunoreactivity and synaptotoxicity with low doses of oleocanthal

    International Nuclear Information System (INIS)

    Pitt, Jason; Roth, William; Lacor, Pascale; Smith, Amos B.; Blankenship, Matthew; Velasco, Pauline; De Felice, Fernanda; Breslin, Paul; Klein, William L.

    2009-01-01

    It now appears likely that soluble oligomers of amyloid-β 1-42 peptide, rather than insoluble fibrils, act as the primary neurotoxin in Alzheimer's disease (AD). Consequently, compounds capable of altering the assembly state of these oligomers (referred to as ADDLs) may have potential for AD therapeutics. Phenolic compounds are of particular interest for their ability to disrupt Aβ oligomerization and reduce pathogenicity. This study has focused on oleocanthal (OC), a naturally-occurring phenolic compound found in extra-virgin olive oil. OC increased the immunoreactivity of soluble Aβ species, when assayed with both sequence- and conformation-specific Aβ antibodies, indicating changes in oligomer structure. Analysis of oligomers in the presence of OC showed an upward shift in MW and a ladder-like distribution of SDS-stable ADDL subspecies. In comparison with control ADDLs, oligomers formed in the presence of OC (Aβ-OC) showed equivalent colocalization at synapses but exhibited greater immunofluorescence as a result of increased antibody recognition. The enhanced signal at synapses was not due to increased synaptic binding, as direct detection of fluorescently-labeled ADDLs showed an overall reduction in ADDL signal in the presence of OC. Decreased binding to synapses was accompanied by significantly less synaptic deterioration assayed by drebrin loss. Additionally, treatment with OC improved antibody clearance of ADDLs. These results indicate oleocanthal is capable of altering the oligomerization state of ADDLs while protecting neurons from the synaptopathological effects of ADDLs and suggest OC as a lead compound for development in AD therapeutics.

  9. Identification and characterization of 4 missense mutations in brown midrib 12 (Bmr12); the caffeic O-methyltranferase (COMT) of sorghum

    Science.gov (United States)

    Modifying lignin content and composition are targets to improve bioenergy crops for cellulosic conversion to biofuels. In sorghum and other C4 grasses, the brown midrib mutants have been shown to reduce lignin content and alter its composition. Bmr12 encodes the sorghum caffeic O-methyltransferase...

  10. Sedimentation equilibrium of a small oligomer-forming membrane protein: effect of histidine protonation on pentameric stability.

    Science.gov (United States)

    Surya, Wahyu; Torres, Jaume

    2015-04-02

    Analytical ultracentrifugation (AUC) can be used to study reversible interactions between macromolecules over a wide range of interaction strengths and under physiological conditions. This makes AUC a method of choice to quantitatively assess stoichiometry and thermodynamics of homo- and hetero-association that are transient and reversible in biochemical processes. In the modality of sedimentation equilibrium (SE), a balance between diffusion and sedimentation provides a profile as a function of radial distance that depends on a specific association model. Herein, a detailed SE protocol is described to determine the size and monomer-monomer association energy of a small membrane protein oligomer using an analytical ultracentrifuge. AUC-ES is label-free, only based on physical principles, and can be used on both water soluble and membrane proteins. An example is shown of the latter, the small hydrophobic (SH) protein in the human respiratory syncytial virus (hRSV), a 65-amino acid polypeptide with a single α-helical transmembrane (TM) domain that forms pentameric ion channels. NMR-based structural data shows that SH protein has two protonatable His residues in its transmembrane domain that are oriented facing the lumen of the channel. SE experiments have been designed to determine how pH affects association constant and the oligomeric size of SH protein. While the pentameric form was preserved in all cases, its association constant was reduced at low pH. These data are in agreement with a similar pH dependency observed for SH channel activity, consistent with a lumenal orientation of the two His residues in SH protein. The latter may experience electrostatic repulsion and reduced oligomer stability at low pH. In summary, this method is applicable whenever quantitative information on subtle protein-protein association changes in physiological conditions have to be measured.

  11. Structural Investigations of on-pathway Oligomers of α-Synuclein

    DEFF Research Database (Denmark)

    Pedersen, Martin Nors; Horvath, Istvan; Weise, Christoph F.

    Academy of Sciences of the United States of America 108(8): 3246-3251. Horvath, I., et al. (2012). "Mechanisms of protein oligomerization: In-hibitor of functional amyloids templates a-synuclein fibrilla-tion." Journal of the American Chemical Society. Spillantini, M. G., et al. (1997). "[alpha...... by decomposition of SAXS data from the evolving fibrillating solution (Giehm et al. 2011). NMR data have furthermore suggested that the C-terminal is exposed on oligomers obtained by incubation with the ligand FN075 (Horvath et al. 2012). In this study we aim at obtaining SAXS data from isolated stabilized...... oligomer (MAX-lab, May 2012); data analysis is in progress. ITC experiments are furthermore planned to more accurately determine the stoichiometry between α-synuclein and FN075. Horvath and co-workers have already shown that the FN075 stabilized oligomer is on pathway. We have shown that the in...

  12. Flame retardant cotton fabrics by electron beam-induced polymerization of vinyl phosphonate oligomer

    International Nuclear Information System (INIS)

    Sawai, Takeshi; Ametani, Kazuo; Enomoto, Ichiro

    1988-01-01

    Vinyl phosphonate oligomer is presently used commercially as a cellulosic flame retardant in conjugation with N-methylol acrylamide, using a persulfate catalyst and a thermal cure. This combination can also be cured at room temperature with electron beams, as can the vinyl phosphonate alone. For the textile application, fixation of flame retardants by electron beams with low energy is one of the most promising applications. For the purpose of preparing flame resistant cotton fabrics such as bed sheets and pajamas, flame retardant curing of vinyl phosphonate oligomer on cotton fabrics was examined using electron beams from a self-sealed electron beam processor and gamma rays from a 60 Co source. A joint investigation was undertaken by the Tokyo Metropolitan Textile Research Institute and Tokyo Metropolitan Isotope Research Center to determine the feasibility of curing vinyl phosphonate oligomer on the cotton fabrics for textile finishing. (author)

  13. Synthesis of alginate oligomers by gamma irradiation and to investigate its antioxidant and prebiotic activity

    International Nuclear Information System (INIS)

    Bhoir, S.A.; Chawla, S.P.

    2016-01-01

    Alginate oligomers formed by alginate lyase have been reported to possess antioxidant activity as well as prebiotic activity. Hence, utility of gamma radiation to depolymerise alginate in its aqueous solution was investigated and its antioxidant and prebiotic activities were screened. 1% aqueous solution of sodium alginate was subjected to gamma irradiation and it's reducing power and ability to scavenge DPPH". and O_2"."."-, chelate iron and prevent heat induced β-carotene bleaching was determined. Prebiotic activity was determined by using alginate oligomers to promote prebiotic activity of Lactobacillus plantarum against E coli. Gamma radiation induced depolymerisation of alginate resulted in formation of oligomers with antioxidant and prebiotic activity. These polymers are potential candidates for utilization as natural preservatives and functional foods

  14. Cytoprotection of Human Endothelial Cells From Menadione Cytotoxicity by Caffeic Acid Phenethyl Ester: The Role of Heme Oxygenase-1

    Science.gov (United States)

    2008-06-08

    cells (HUVEC) to evaluate potential gene expression involvement. CAPE exhibited dose- dependent cytoprotection of HUVEC. A gene screen with...highly induced (8.25-fold) by CAPE compared to DMSO control. To validate this particular microarray screening result, quantitative real-time RT-PCR was...the Nrf2 transcription factor in response to the antioxidant phytochemical carnosol. The Journal of Biological Chemistry 279, 8919–8929. Minami, T

  15. Comparative evaluation of antibacterial activity of caffeic acid phenethyl ester and PLGA nanoparticle formulation by different methods

    International Nuclear Information System (INIS)

    Arasoglu, Tülin; Mansuroglu, Banu; Derman, Serap

    2016-01-01

    The aim of the present study was to evaluate the antimicrobial activity of nanoparticle and free formulations of the CAPE compound using different methods and comparing the results in the literature for the first time. In parallel with this purpose, encapsulation of CAPE with the PLGA nanoparticle system (CAPE-PLGA-NPs) and characterization of nanoparticles were carried out. Afterwards, antimicrobial activity of free CAPE and CAPE-PLGA-NPs was determined using agar well diffusion, disk diffusion, broth microdilution and reduction percentage methods. P. aeroginosa, E. coli, S. aureus and methicillin-resistant S. aureus (MRSA) were chosen as model bacteria since they have different cell wall structures. CAPE-PLGA-NPs within the range of 214.0 ± 8.80 nm particle size and with an encapsulation efficiency of 91.59 ± 4.97% were prepared using the oil-in-water (o–w) single-emulsion solvent evaporation method. The microbiological results indicated that free CAPE did not have any antimicrobial activity in any of the applied methods whereas CAPE-PLGA-NPs had significant antimicrobial activity in both broth dilution and reduction percentage methods. CAPE-PLGA-NPs showed moderate antimicrobial activity against S. aureus and MRSA strains particularly in hourly measurements at 30.63 and 61.25 μg ml −1 concentrations (both p < 0.05), whereas they failed to show antimicrobial activity against Gram-negative bacteria (P. aeroginosa and E. coli, p > 0.05). In the reduction percentage method, in which the highest results of antimicrobial activity were obtained, it was observed that the antimicrobial effect on S. aureus was more long-standing (3 days) and higher in reduction percentage (over 90%). The appearance of antibacterial activity of CAPE-PLGA-NPs may be related to higher penetration into cells due to low solubility of free CAPE in the aqueous medium. Additionally, the biocompatible and biodegradable PLGA nanoparticles could be an alternative to solvents such as ethanol, methanol or DMSO. Consequently, obtained results show that the method of selection is extremely important and will influence the results. Thus, broth microdilution and reduction percentage methods can be recommended as reliable and useful screening methods for determination of antimicrobial activity of PLGA nanoparticle formulations used particularly in drug delivery systems compared to both agar well and disk diffusion methods. (paper)

  16. Comparative evaluation of antibacterial activity of caffeic acid phenethyl ester and PLGA nanoparticle formulation by different methods

    Science.gov (United States)

    Arasoglu, Tülin; Derman, Serap; Mansuroglu, Banu

    2016-01-01

    The aim of the present study was to evaluate the antimicrobial activity of nanoparticle and free formulations of the CAPE compound using different methods and comparing the results in the literature for the first time. In parallel with this purpose, encapsulation of CAPE with the PLGA nanoparticle system (CAPE-PLGA-NPs) and characterization of nanoparticles were carried out. Afterwards, antimicrobial activity of free CAPE and CAPE-PLGA-NPs was determined using agar well diffusion, disk diffusion, broth microdilution and reduction percentage methods. P. aeroginosa, E. coli, S. aureus and methicillin-resistant S. aureus (MRSA) were chosen as model bacteria since they have different cell wall structures. CAPE-PLGA-NPs within the range of 214.0 ± 8.80 nm particle size and with an encapsulation efficiency of 91.59 ± 4.97% were prepared using the oil-in-water (o-w) single-emulsion solvent evaporation method. The microbiological results indicated that free CAPE did not have any antimicrobial activity in any of the applied methods whereas CAPE-PLGA-NPs had significant antimicrobial activity in both broth dilution and reduction percentage methods. CAPE-PLGA-NPs showed moderate antimicrobial activity against S. aureus and MRSA strains particularly in hourly measurements at 30.63 and 61.25 μg ml-1 concentrations (both p 0.05). In the reduction percentage method, in which the highest results of antimicrobial activity were obtained, it was observed that the antimicrobial effect on S. aureus was more long-standing (3 days) and higher in reduction percentage (over 90%). The appearance of antibacterial activity of CAPE-PLGA-NPs may be related to higher penetration into cells due to low solubility of free CAPE in the aqueous medium. Additionally, the biocompatible and biodegradable PLGA nanoparticles could be an alternative to solvents such as ethanol, methanol or DMSO. Consequently, obtained results show that the method of selection is extremely important and will influence the results. Thus, broth microdilution and reduction percentage methods can be recommended as reliable and useful screening methods for determination of antimicrobial activity of PLGA nanoparticle formulations used particularly in drug delivery systems compared to both agar well and disk diffusion methods.

  17. Thio-urethane oligomers improve the properties of light-cured resin cements.

    Science.gov (United States)

    Bacchi, Ataís; Consani, Rafael L; Martim, Gedalias C; Pfeifer, Carmem S

    2015-05-01

    Thio-urethanes were synthesized by combining 1,6-hexanediol-diissocyante (aliphatic) with pentaerythritol tetra-3-mercaptopropionate (PETMP) or 1,3-bis(1-isocyanato-1-methylethyl)benzene (aromatic) with trimethylol-tris-3-mercaptopropionate (TMP), at 1:2 isocyanate:thiol, leaving pendant thiols. Oligomers were added at 10-30 phr to BisGMA-UDMA-TEGDMA (5:3:2, BUT). 25 wt% silanated inorganic fillers were added. Commercial cement (Relyx Veneer, 3M-ESPE) was also evaluated with 10-20 phr of aromatic oligomer. Near-IR was used to follow methacrylate conversion (DC) and rate of polymerization (Rpmax). Mechanical properties were evaluated in three-point bending (ISO 4049) for flexural strength/modulus (FS/FM, and toughness), and notched specimens (ASTM Standard E399-90) for fracture toughness (KIC). Polymerization stress (PS) was measured on the Bioman. Volumetric shrinkage (VS, %) was measured with the bonded disk technique. Results were analyzed with ANOVA/Tukey's test (α=5%). In general terms, for BUT cements, conversion and mechanical properties in flexure increased for selected groups with the addition of thio-urethane oligomers. The aromatic versions resulted in greater FS/FM than aliphatic. Fracture toughness increased by two-fold in the experimental groups (from 1.17 ± 0.36 MPam(1/2) to around 3.23 ± 0.22 MPam(1/2)). Rpmax decreased with the addition of thio-urethanes, though the vitrification point was not statistically different from the control. VS and PS decreased with both oligomers. For the commercial cement, 20 phr of oligomer increased DC, vitrification, reduced Rpmax and also significantly increased KIC, and reduced PS and FM. Thio-urethane oligomers were shown to favorably modify conventional dimethacrylate networks. Significant reductions in polymerization stress were achieved at the same time conversion and fracture toughness increased. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Synthesis and Electronic Properties of Length-Defined 9,10-Anthrylene-Butadiynylene Oligomers.

    Science.gov (United States)

    Nagaoka, Maiko; Tsurumaki, Eiji; Nishiuchi, Mai; Iwanaga, Tetsuo; Toyota, Shinji

    2018-05-18

    Linear π-conjugated oligomers consisting of anthracene and diacetylene units were readily synthesized by a one-pot process that involved desilylation and oxidative coupling from appropriate building units. We were able to isolate length-defined oligomers ranging from 2-mer to 6-mer as stable and soluble solids. The bathochromic shifts in the UV-vis spectra suggested that the π-conjugation was extended with elongation of the linear chain. Cyclic voltammetric measurements showed characteristic reversible oxidation waves that were dependent on the number of anthracene units.

  19. Structure and properties of binary mixtures polystyrene-epoxyacrylic oligomers irradiated by electrons

    International Nuclear Information System (INIS)

    Lomonosova, N.V.

    1995-01-01

    Using the methods of birefringence, isometrical heating, IR-dichroism and thermal optical analysis change in structure of oriented polymer-oligomer systems on the base of PS (M>10 6 ) and epoxyacrylic (EA) oligomers of aliphatic and aromatic structure is studied during the process of irradiation by fast electrons. Their mechanical properties are studied and it is established that introduction of aliphatic epoxyacrylate to PS and subsequent irradiation allow to obtain composite materials with higher values of strength, modulus of elasticity and softening temperature in isotropic and oriented states. 6 refs., 2 figs., 3 tabs

  20. Extended Ladder-Type Benzo[ k ]tetraphene-Derived Oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jongbok [Department of Chemistry, Texas A& M University, 3255 TAMU College Station TX 77843-3255 USA; Li, Huanbin [MOE Key Laboratory of Macromolecular Synthesis and Functionalization, State Key Laboratory of Silicon Materials, Department of Polymer Science and Engineering, Zhejiang University, 38 Zheda Rd Hangzhou 310027 China; Kalin, Alexander J. [Department of Chemistry, Texas A& M University, 3255 TAMU College Station TX 77843-3255 USA; Yuan, Tianyu [Department of Materials Science and Engineering, Texas A& M University, 3003 TAMU College Station TX 77843-3003 USA; Wang, Chenxu [Department of Materials Science and Engineering, Texas A& M University, 3003 TAMU College Station TX 77843-3003 USA; Olson, Troy [Department of Chemistry, Texas A& M University, 3255 TAMU College Station TX 77843-3255 USA; Li, Hanying [MOE Key Laboratory of Macromolecular Synthesis and Functionalization, State Key Laboratory of Silicon Materials, Department of Polymer Science and Engineering, Zhejiang University, 38 Zheda Rd Hangzhou 310027 China; Fang, Lei [Department of Chemistry, Texas A& M University, 3255 TAMU College Station TX 77843-3255 USA; Department of Materials Science and Engineering, Texas A& M University, 3003 TAMU College Station TX 77843-3003 USA

    2017-10-02

    Well-defined, fused-ring aromatic oligomers represent promising candidates for the fundamental understanding and application of advanced carbon-rich materials, though bottom-up synthesis and structure–property correlation of these compounds remain challenging. In this work, an efficient synthetic route was employed to construct extended benzo[k]tetraphene-derived oligomers with up to 13 fused rings. The molecular and electronic structures of these compounds were clearly elucidated. Precise correlation of molecular sizes and crystallization dynamics was established, thus demonstrating the pivotal balance between intermolecular interaction and molecular mobility for optimized processing of highly ordered solids of these extended conjugated molecules.

  1. Preparation of {sup 111}In-DTPA morpholino oligomer for low abdominal accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Liu Guozheng, E-mail: guozheng.liu@umassmed.ed [Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655-0243 (United States); Dou Shuping; Rusckowski, Mary [Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655-0243 (United States); Greiner, Dale [Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01655-0243 (United States); Hnatowich, Donald [Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655-0243 (United States)

    2010-09-15

    An ability to quantitate the beta cell mass by noninvasive nuclear imaging will be very useful in the prevention, diagnosis, and treatment of diabetes. However, to be successful, radioactivity from the pancreas must not be obscured by the background radioactivity in the abdomen. Pretargeting offers the promise of achieving high target organ to normal tissue ratios. In preparation for pancreas imaging studies by pretargeting using morpholino oligomers (MORF/cMORF), it was necessary to develop a simple and efficient method to radiolabel the cMORF effector. Because we have shown that labeling the cMORF with {sup 111}In via DTPA reduces excretion into the intestines compared to labeling with {sup 99m}Tc via MAG{sub 3}, the conjugation of DTPA to cMORF was investigated for {sup 111}In labeling. The amine-derivatized cMORF was conjugated with DTPA using 1-ethyl-3(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) as an alternative to the conventional cyclic anhydride. The conjugation efficiency (represented by the number of DTPA groups attached per cMORF) was investigated by changing the EDC, DTPA, and cMORF molar ratios. Different open columns were considered for the purification of DTPA-cMORF. Before conjugation, each cMORF molecule was confirmed to have an amine by trinitrobenzene sulfonic acid (TNBS) assay using the {omega}-amino butyric acid as positive standard and the non-amine derivatized cMORF as negative standard. The average number of DTPA groups per cMORF was 0.15-0.20 following the conjugation over a cMORF/DTPA molar ratio of 0.5-5 and over a cMORF/EDC molar ratio of 20-60. The conjugation efficiency was lower than expected probably due to steric hindrance. A 1x50 cm P-4 column using ammonium acetate as eluting buffer provided an adequate separation of DTPA-cMORF from free DTPA. The {sup 111}In labeling efficiency by transchelation from acetate exceeded 95%, thus avoiding the need for postlabeling purification. Despite the lower than expected conjugation

  2. Cholesterol facilitates interactions between α-synuclein oligomers and charge-neutral membranes

    DEFF Research Database (Denmark)

    van Maarschalkerweerd, Andreas; Vetri, Valeria; Vestergaard, Bente

    2015-01-01

    composed of anionic lipids, while the more physiologically relevant zwitterionic lipids remain intact. We present experimental evidence for significant morphological changes in zwitterionic membranes containing cholesterol, induced by α-synuclein oligomers. Depending on the lipid composition, model...... of cholesterol for mediating interactions between physiologically relevant membranes and α-synuclein....

  3. Organization in sol-gel polymerization of methacrylate co-oligomers containing trimethoxysilylpropyl methacrylate

    Czech Academy of Sciences Publication Activity Database

    Vraštil, J.; Matějka, Libor; Špaček, V.; Večeřa, M.; Prokůpek, L.

    2005-01-01

    Roč. 46, č. 25 (2005), s. 11232-11240 ISSN 0032-3861 Institutional research plan: CEZ:AV0Z40500505 Keywords : organic-inorganic hybrid * sol-gel process * oligomers Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.849, year: 2005

  4. Side-chain degradation of ultrapure π-conjugated oligomers: implications for organic electronics

    NARCIS (Netherlands)

    Abbel, R.J.; Wolffs, M.; Bovee, R.A.A.; Dongen, van J.L.J.; Lou, X.W.; Henze, O.; Feast, W.J.; Meijer, E.W.; Schenning, A.P.H.J.

    2009-01-01

    The degrdn. of two defect-free pi-conjugated oligomers and the participation of their solubilizing side chains in the process are studied in unprecedented detail. The detected intermediate products reveal a mechanism of successive shortening of alkyl and oligo(ethylene glycol) substituents.

  5. Interface Bond Improvement of Sisal Fibre Reinforced Polylactide Composites with Added Epoxy Oligomer.

    Science.gov (United States)

    Hao, Mingyang; Wu, Hongwu; Qiu, Feng; Wang, Xiwen

    2018-03-07

    To improve the interfacial bonding of sisal fiber-reinforced polylactide biocomposites, polylactide (PLA) and sisal fibers (SF) were melt-blended to fabricate bio-based composites via in situ reactive interfacial compatibilization with addition of a commercial grade epoxy-functionalized oligomer Joncryl ADR @ -4368 (ADR). The FTIR (Fourier Transform infrared spectroscopy) analysis and SEM (scanning electron microscope) characterization demonstrated that the PLA molecular chain was bonded to the fiber surface and the epoxy-functionalized oligomer played a hinge-like role between the sisal fibers and the PLA matrix, which resulted in improved interfacial adhesion between the fibers and the PLA matrix. The interfacial reaction and microstructures of composites were further investigated by thermal and rheological analyses, which indicated that the mobility of the PLA molecular chain in composites was restricted because of the introduction of the ADR oligomer, which in turn reflected the improved interfacial interaction between SF and the PLA matrix. These results were further justified with the calculation of activation energies of glass transition relaxation (∆ E a ) by dynamic mechanical analysis. The mechanical properties of PLA/SF composites were simultaneously reinforced and toughened with the addition of ADR oligomer. The interfacial interaction and structure-properties relationship of the composites are the key points of this study.

  6. Structures of Metalloporphyrin-Oligomer Multianions: Cofacial versus Coplanar Motifs as Resolved by Ion Mobility Spectrometry.

    Science.gov (United States)

    Brendle, Katrina; Schwarz, Ulrike; Jäger, Patrick; Weis, Patrick; Kappes, Manfred

    2016-11-03

    We have combined ion mobility mass spectrometry with quantum chemical calculations to investigate the gas-phase structures of multiply negatively charged oligomers of meso-tetra(4-sulfonatophenyl)metalloporphyrins comprising the divalent metal centers Zn II , Cu II , and Pd II . Sets of candidate structures were obtained by geometry optimizations based on calculations at both the semiempirical PM7 and density functional theory (DFT) levels. The corresponding theoretical cross sections were calculated with the projection approximation and also with the trajectory method. By comparing these collision cross sections with the respective experimental values we were able to assign oligomer structures up to the tetramer. In most cases the cross sections of the lowest energy isomers predicted by theory were found to agree with the measurements to within the experimental uncertainty (2%). Specifically, we find that for a given oligomer size the structures are independent of the metal center but depend strongly on the charge state. Oligomers in low charge states with a correspondingly larger number of sodium counterions tend to form stacked, cofacial structures reminiscent of H-aggregate motifs observed in solution. By contrast, in higher charge states, the stack opens to form coplanar structures.

  7. Detection of aniline oligomers on polyaniline-gold interface using resonance Raman scattering

    Czech Academy of Sciences Publication Activity Database

    Trchová, Miroslava; Morávková, Zuzana; Dybal, Jiří; Stejskal, Jaroslav

    2014-01-01

    Roč. 6, č. 2 (2014), s. 942-950 ISSN 1944-8244 R&D Projects: GA ČR GAP205/12/0911; GA ČR(CZ) GA13-00270S Institutional support: RVO:61389013 Keywords : polyaniline * aniline oligomers * Raman spectroscopy Subject RIV: CD - Macromolecular Chemistry Impact factor: 6.723, year: 2014

  8. Multicolored, Low-Voltage-Driven, Flexible Organic Electrochromic Devices Based on Oligomers.

    Science.gov (United States)

    Wan, Zhijun; Zeng, Jinming; Li, Hui; Liu, Ping; Deng, Wenji

    2018-04-20

    In this study, a series of organic conjugated oligomers containing 3,4-ethylenedioxythiophene (EDOT) and aromatic groups are synthesized, which are as follows: 2,5-di(methyl benzoate)-3,4-ethylenedioxy-thiophene (1EDOT-2B-COOCH 3 ), 5,5'-di(methyl benzoate)-2,2'-bi(3,4-ethylenedioxythiophene) (2EDOT-2B-COOCH 3 ), 5,5″-di(methyl benzoate)-2,2':5',2″-ter(3,4-ethylenedioxythiophene) (3EDOT-2B-COOCH 3 ), and 5,5″'-di(methyl benzoate)-2,2':5',2″: 5″,2″'-quater(3,4-ethylenedioxythiophene) (4EDOT-2B-COOCH 3 ). Using these oligomers as active materials, flexible organic electrochromic devices are fabricated. The device structure is indium tin oxide-PET plastic slide (ITO-PET)/active layer/conducting gel/ITO-PET, and the electrochromic properties of oligomers are investigated. These oligomers exhibit reversible color changes upon electrochemical doping and dedoping. The highest optical contrast is exhibited by 4EDOT-2B-COOCH 3 , which is 75.2% at 700 nm. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Genotoxicity of styrene oligomers extracted from polystyrene intended for use in contact with food

    Directory of Open Access Journals (Sweden)

    Makoto Nakai

    2014-01-01

    Full Text Available Here, we conducted in vitro genotoxicity tests to evaluate the genotoxicity of styrene oligomers extracted from polystyrene intended for use in contact with food. Styrene oligomers were extracted with acetone and the extract was subjected to the Ames test (OECD test guideline No. 471 and the in vitro chromosomal aberration test (OECD test guideline No. 473 under good laboratory practice conditions. The concentrations of styrene dimers and trimers in the concentrated extract were 540 and 13,431 ppm, respectively. Extraction with acetone provided markedly higher concentrations of styrene oligomers compared with extraction with 50% ethanol aqueous solution, which is the food simulant currently recommended for use in safety assessments of polystyrene by both the United States Food and Drug Administration and the European Food Safety Authority. And these high concentrations of styrene dimers and trimers were utilized for the evaluation of genotoxicity in vitro. Ames tests using five bacterial tester strains were negative both in the presence or absence of metabolic activation. The in vitro chromosomal aberration test using Chinese hamster lung cells (CHL/IU was also negative. Together, these results suggest that the risk of the genotoxicity of styrene oligomers that migrate from polystyrene food packaging into food is very low.

  10. Ultrafast Photoinduced Electron Transfer in a π-Conjugated Oligomer/Porphyrin Complex

    KAUST Repository

    Aly, Shawkat Mohammede

    2014-10-02

    Controlling charge transfer (CT), charge separation (CS), and charge recombination (CR) at the donor-acceptor interface is extremely important to optimize the conversion efficiency in solar cell devices. In general, ultrafast CT and slow CR are desirable for optimal device performance. In this Letter, the ultrafast excited-state CT between platinum oligomer (DPP-Pt(acac)) as a new electron donor and porphyrin as an electron acceptor is monitored for the first time using femtosecond (fs) transient absorption (TA) spectroscopy with broad-band capability and 120 fs temporal resolution. Turning the CT on/off has been shown to be possible either by switching from an organometallic oligomer to a metal-free oligomer or by controlling the charge density on the nitrogen atom of the porphyrin meso unit. Our time-resolved data show that the CT and CS between DPP-Pt(acac) and cationic porphyrin are ultrafast (approximately 1.5 ps), and the CR is slow (ns time scale), as inferred from the formation and the decay of the cationic and anionic species. We also found that the metallic center in the DPP-Pt(acac) oligomer and the positive charge on the porphyrin are the keys to switching on/off the ultrafast CT process.

  11. High-resolution NMR characterization of low abundance oligomers of amyloid-β without purification.

    Science.gov (United States)

    Kotler, Samuel A; Brender, Jeffrey R; Vivekanandan, Subramanian; Suzuki, Yuta; Yamamoto, Kazutoshi; Monette, Martine; Krishnamoorthy, Janarthanan; Walsh, Patrick; Cauble, Meagan; Holl, Mark M Banaszak; Marsh, E Neil G; Ramamoorthy, Ayyalusamy

    2015-07-03

    Alzheimer's disease is characterized by the misfolding and self-assembly of the amyloidogenic protein amyloid-β (Aβ). The aggregation of Aβ leads to diverse oligomeric states, each of which may be potential targets for intervention. Obtaining insight into Aβ oligomers at the atomic level has been a major challenge to most techniques. Here, we use magic angle spinning recoupling (1)H-(1)H NMR experiments to overcome many of these limitations. Using (1)H-(1)H dipolar couplings as a NMR spectral filter to remove both high and low molecular weight species, we provide atomic-level characterization of a non-fibrillar aggregation product of the Aβ1-40 peptide using non-frozen samples without isotopic labeling. Importantly, this spectral filter allows the detection of the specific oligomer signal without a separate purification procedure. In comparison to other solid-state NMR techniques, the experiment is extraordinarily selective and sensitive. A resolved 2D spectra could be acquired of a small population of oligomers (6 micrograms, 7% of the total) amongst a much larger population of monomers and fibers (93% of the total). By coupling real-time (1)H-(1)H NMR experiments with other biophysical measurements, we show that a stable, primarily disordered Aβ1-40 oligomer 5-15 nm in diameter can form and coexist in parallel with the well-known cross-β-sheet fibrils.

  12. Towards directional assembly of hierarchical structures: aniline oligomers as the model precursors

    Czech Academy of Sciences Publication Activity Database

    Zhao, Y.; Stejskal, Jaroslav; Wang, J.

    2013-01-01

    Roč. 5, č. 7 (2013), s. 2620-2626 ISSN 2040-3364 R&D Projects: GA ČR GAP205/12/0911 Institutional support: RVO:61389013 Keywords : aniline oligomers * hierarchical nanostructures * microflowers Subject RIV: CD - Macromolecular Chemistry Impact factor: 6.739, year: 2013

  13. Alpha-synuclein oligomers - neurotoxic molecules in Parkinson’s disease and other Lewy body disorders

    Directory of Open Access Journals (Sweden)

    Martin Ingelsson

    2016-09-01

    Full Text Available Adverse intra- and extracellular effects of toxic α-synuclein are believed to be central to the pathogenesis in Parkinson’s disease and other disorders with Lewy body pathology in the nervous system. One of the physiological roles of α-synuclein relates to the regulation of neurotransmitter release at the presynapse, although it is still unclear whether this mechanism depends on the action of monomers or smaller oligomers. As for the pathogenicity, accumulating evidence suggest that prefibrillar species, rather than the deposits per se, are responsible for the toxicity in affected cells. In particular, larger oligomers or protofibrils of α-synuclein have been shown to impair protein degradation as well as the function of several organelles, such as the mitochondria and the endoplasmic reticulum. Accumulating evidence further suggest that oligomers/protofibrils may have a toxic effect on the synapse, which may lead to disrupted electrophysiological properties. In addition, recent data indicate that oligomeric α-synuclein species can spread between cells, either as free-floating proteins or via extracellular vesicles, and thereby act as seeds to propagate disease between interconnected brain regions. Taken together, several lines of evidence suggest that α-synuclein have neurotoxic properties and therefore should be an appropriate molecular target for therapeutic intervention in Parkinson’s disease and other disorders with Lewy pathology. In this context, immunotherapy with monoclonal antibodies against α-synuclein oligomers/protofibrils should be a particularly attractive treatment option.

  14. Optimization of the All-D Peptide D3 for Aβ Oligomer Elimination.

    Directory of Open Access Journals (Sweden)

    Antonia Nicole Klein

    Full Text Available The aggregation of amyloid-β (Aβ is postulated to be the crucial event in Alzheimer's disease (AD. In particular, small neurotoxic Aβ oligomers are considered to be responsible for the development and progression of AD. Therefore, elimination of thesis oligomers represents a potential causal therapy of AD. Starting from the well-characterized d-enantiomeric peptide D3, we identified D3 derivatives that bind monomeric Aβ. The underlying hypothesis is that ligands bind monomeric Aβ and stabilize these species within the various equilibria with Aβ assemblies, leading ultimately to the elimination of Aβ oligomers. One of the hereby identified d-peptides, DB3, and a head-to-tail tandem of DB3, DB3DB3, were studied in detail. Both peptides were found to: (i inhibit the formation of Thioflavin T-positive fibrils; (ii bind to Aβ monomers with micromolar affinities; (iii eliminate Aβ oligomers; (iv reduce Aβ-induced cytotoxicity; and (v disassemble preformed Aβ aggregates. The beneficial effects of DB3 were improved by DB3DB3, which showed highly enhanced efficacy. Our approach yielded Aβ monomer-stabilizing ligands that can be investigated as a suitable therapeutic strategy against AD.

  15. High-capacity conductive nanocellulose paper sheets for electrochemically controlled extraction of DNA oligomers.

    Directory of Open Access Journals (Sweden)

    Aamir Razaq

    Full Text Available Highly porous polypyrrole (PPy-nanocellulose paper sheets have been evaluated as inexpensive and disposable electrochemically controlled three-dimensional solid phase extraction materials. The composites, which had a total anion exchange capacity of about 1.1 mol kg(-1, were used for extraction and subsequent release of negatively charged fluorophore tagged DNA oligomers via galvanostatic oxidation and reduction of a 30-50 nm conformal PPy layer on the cellulose substrate. The ion exchange capacity, which was, at least, two orders of magnitude higher than those previously reached in electrochemically controlled extraction, originated from the high surface area (i.e. 80 m(2 g(-1 of the porous composites and the thin PPy layer which ensured excellent access to the ion exchange material. This enabled the extractions to be carried out faster and with better control of the PPy charge than with previously employed approaches. Experiments in equimolar mixtures of (dT(6, (dT(20, and (dT(40 DNA oligomers showed that all oligomers could be extracted, and that the smallest oligomer was preferentially released with an efficiency of up to 40% during the reduction of the PPy layer. These results indicate that the present material is very promising for the development of inexpensive and efficient electrochemically controlled ion-exchange membranes for batch-wise extraction of biomolecules.

  16. Carbonization of aniline oligomers to electrically polarizable particles and their use in electrorheology

    Czech Academy of Sciences Publication Activity Database

    Plachý, T.; Sedlačík, M.; Pavlínek, V.; Trchová, Miroslava; Morávková, Zuzana; Stejskal, Jaroslav

    2014-01-01

    Roč. 256, 15 November (2014), s. 398-406 ISSN 1385-8947 R&D Projects: GA ČR GAP205/12/0911; GA ČR(CZ) GA13-08944S Institutional support: RVO:61389013 Keywords : aniline * aniline oligomers * carbonization Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.321, year: 2014

  17. Solid state properties of oligomers containing dithienothiophene or fluorene residues suitable for field effect transistor devices

    International Nuclear Information System (INIS)

    Porzio, William; Destri, Silvia; Giovanella, Umberto; Pasini, Mariacecilia; Marin, Luminita; Iosip, Mariana Dana; Campione, Marcello

    2007-01-01

    A series of three thiophene based oligomers has been extensively characterized. The chemical design has been addressed to obtain ionization potential (IP) and electronic affinity (EA) values matching the work function of commonly used electrode materials. Such IP and EA values were tested by cyclovoltammetry. In order to tune electron-donation and drawing strength the sequence of the molecule subunits in the oligomer has been varied. The thermal properties with particular reference to their stability during preparation and operation were checked by using differential scanning calorimetry, polarised light microscopy and thermogravimetric analysis techniques. Prototypes of thin film field effect transistor, based on this series of oligomers have been electrically and structurally characterized. The long axes of the molecules are oriented nearly perpendicular to the gate insulator, in agreement with both highly sensitive X-ray diffraction and atomic force microscopy. From powder diffraction data the structure of oligomer I was solved. A general relation is envisaged between charge mobility and packing closeness in the series. For the most promising molecule a study of mobility/temperature behaviour was performed yielding interesting results

  18. Structure–property relationships of synthetic organophosphorus flame retardant oligomers by thermal analysis

    International Nuclear Information System (INIS)

    Bai, Zhiman; Wang, Xin; Tang, Gang; Song, Lei; Hu, Yuan; Yuen, Richard K.K.

    2013-01-01

    Highlights: • Oligomers with different chemical components in molecular chains were synthesized. • FP-3 containing three IFR components possessed high thermal stability. • FP-3 possessed lowest flammability. • FP-3 exhibited a synergistic interaction between gas and condensed phase. - Abstract: A series of flame retardant oligomers with different chemical components in molecular chains, designated as FP-1, FP-2 and FP-3, respectively, were successfully synthesized using solution polycondensation and well characterized. The thermal properties and flammability of these oligomers were investigated by thermogravimetric analysis (TGA) and microscale combustion calorimeter (MCC). The results demonstrated that FP-3 had the lowest flammability in terms of the lowest maximum mass loss rate, and FP-1 possessed the highest thermal stability and char yield, due to its higher stable hexatomic ring structure of piperazine compared with the linear alkane chain structure of neopentyl glycol. The gases evolved during decomposition were analyzed using Fourier transform infrared coupled with the thermogravimetric analyzer (TG–IR) technique. The char residues of the flame retardant oligomers were investigated by scanning electron microscopy (SEM) and Raman spectroscopy. The results demonstrated that FP-3 exhibited a synergistic interaction between the gas phase and condensation phase, increasing its flame retardancy

  19. Formation of soluble amyloid oligomers and amyloid fibrils by the multifunctional protein vitronectin

    Directory of Open Access Journals (Sweden)

    Langen Ralf

    2008-10-01

    Full Text Available Abstract Background The multifunctional protein vitronectin is present within the deposits associated with Alzheimer disease (AD, age-related macular degeneration (AMD, atherosclerosis, systemic amyloidoses, and glomerulonephritis. The extent to which vitronectin contributes to amyloid formation within these plaques, which contain misfolded, amyloidogenic proteins, and the role of vitronectin in the pathophysiology of the aforementioned diseases is currently unknown. The investigation of vitronectin aggregation is significant since the formation of oligomeric and fibrillar structures are common features of amyloid proteins. Results We observed vitronectin immunoreactivity in senile plaques of AD brain, which exhibited overlap with the amyloid fibril-specific OC antibody, suggesting that vitronectin is deposited at sites of amyloid formation. Of particular interest is the growing body of evidence indicating that soluble nonfibrillar oligomers may be responsible for the development and progression of amyloid diseases. In this study we demonstrate that both plasma-purified and recombinant human vitronectin readily form spherical oligomers and typical amyloid fibrils. Vitronectin oligomers are toxic to cultured neuroblastoma and retinal pigment epithelium (RPE cells, possibly via a membrane-dependent mechanism, as they cause leakage of synthetic vesicles. Oligomer toxicity was attenuated in RPE cells by the anti-oligomer A11 antibody. Vitronectin fibrils contain a C-terminal protease-resistant fragment, which may approximate the core region of residues essential to amyloid formation. Conclusion These data reveal the propensity of vitronectin to behave as an amyloid protein and put forth the possibilities that accumulation of misfolded vitronectin may contribute to aggregate formation seen in age-related amyloid diseases.

  20. Backbone conformation affects duplex initiation and duplex propagation in hybridisation of synthetic H-bonding oligomers.

    Science.gov (United States)

    Iadevaia, Giulia; Núñez-Villanueva, Diego; Stross, Alexander E; Hunter, Christopher A

    2018-06-06

    Synthetic oligomers equipped with complementary H-bond donor and acceptor side chains form multiply H-bonded duplexes in organic solvents. Comparison of the duplex forming properties of four families of oligomers with different backbones shows that formation of an extended duplex with three or four inter-strand H-bonds is more challenging than formation of complexes that make only two H-bonds. The stabilities of 1 : 1 complexes formed between length complementary homo-oligomers equipped with either phosphine oxide or phenol recognition modules were measured in toluene. When the backbone is very flexible (pentane-1,5-diyl thioether), the stability increases uniformly by an order of magnitude for each additional base-pair added to the duplex: the effective molarities for formation of the first intramolecular H-bond (duplex initiation) and subsequent intramolecular H-bonds (duplex propagation) are similar. This flexible system is compared with three more rigid backbones that are isomeric combinations of an aromatic ring and methylene groups. One of the rigid systems behaves in exactly the same way as the flexible backbone, but the other two do not. For these systems, the effective molarity for formation of the first intramolecular H-bond is the same as that found for the other two backbones, but additional H-bonds are not formed between the longer oligomers. The effective molarities are too low for duplex propagation in these systems, because the oligomer backbones cannot adopt conformations compatible with formation of an extended duplex.

  1. PrP(Sc-specific antibodies with the ability to immunodetect prion oligomers.

    Directory of Open Access Journals (Sweden)

    Mourad Tayebi

    Full Text Available The development of antibodies with binding capacity towards soluble oligomeric forms of PrPSc recognised in the aggregation process in early stage of the disease would be of paramount importance in diagnosing prion diseases before extensive neuropathology has ensued. As blood transfusion appears to be efficient in the transmission of the infectious prion agent, there is an urgent need to develop reagents that would specifically recognize oligomeric forms of the abnormally folded prion protein, PrPSc.To that end, we show that anti-PrP monoclonal antibodies (called PRIOC mAbs derived from mice immunised with native PrP-coated microbeads are able to immunodetect oligomers/multimers of PrPSc. Oligomer-specific immunoreactivity displayed by these PRIOC mAbs was demonstrated as large aggregates of immunoreactive deposits in prion-permissive neuroblastoma cell lines but not in equivalent non-infected or prn-p(0/0 cell lines. In contrast, an anti-monomer PrP antibody displayed diffuse immunoreactivity restricted to the cell membrane. Furthermore, our PRIOC mAbs did not display any binding with monomeric recombinant and cellular prion proteins but strongly detected PrPSc oligomers as shown by a newly developed sensitive and specific ELISA. Finally, PrioC antibodies were also able to bind soluble oligomers formed of Aβ and α-synuclein. These findings demonstrate the potential use of anti-prion antibodies that bind PrPSc oligomers, recognised in early stage of the disease, for the diagnosis of prion diseases in blood and other body fluids.

  2. Thermodynamically stable amyloid-β monomers have much lower membrane affinity than the small oligomers

    Directory of Open Access Journals (Sweden)

    Bidyut eSarkar

    2013-04-01

    Full Text Available Amyloid beta (Aβ is an extracellular 39-43 residue long peptide present in the mammalian cerebrospinal fluid, whose aggregation is associated with Alzheimer’s disease. Small oligomers of Aβ are currently thought to be the key to toxicity. However, it is not clear why the monomers of Aβ are non-toxic, and at what stage of aggregation toxicity emerges. Interactions of Aβ with cell membranes is thought to be the initiator of toxicity, but membrane-binding studies with different preparations of monomers and oligomers have not settled this issue. We have earlier found that thermodynamically stable Aβ monomers emerge spontaneously from oligomeric mixtures upon long term incubation in physiological solutions (Nag et al, JBC, 2011. Here we show that the membrane-affinity of these stable Aβ monomers is much lower than that of a mixture of small oligomers (containing dimers to decamers, providing a clue to the emergence of toxicity. Fluorescently labeled Aβ40 monomers show negligible binding to cell membranes of a neuronal cell line (RN46A at physiological concentrations (250 nM, while oligomers at the same concentrations show strong binding within 30 minutes of incubation. The increased affinity most likely does not require any specific neuronal receptor, since this difference in membrane-affinity was also observed in a somatic cell-line (HEK 293T. Similar results are also obtained for Aβ42 monomers and oligomers. Minimal amount of cell death is observed at these concentrations even after 36 hours of incubation. It is likely that membrane binding precedes subsequent slower toxic events induced by Aβ. Our results a provide an explanation for the non-toxic nature of Aβ monomers, b suggest that Aβ toxicity emerges at the initial oligomeric phase, and c provide a quick assay for monitoring the benign-to-toxic transformation of Aβ.

  3. Natural amyloid-β oligomers acutely impair the formation of a contextual fear memory in mice.

    Science.gov (United States)

    Kittelberger, Kara A; Piazza, Fabrizio; Tesco, Giuseppina; Reijmers, Leon G

    2012-01-01

    Memory loss is one of the hallmark symptoms of Alzheimer's disease (AD). It has been proposed that soluble amyloid-beta (Abeta) oligomers acutely impair neuronal function and thereby memory. We here report that natural Abeta oligomers acutely impair contextual fear memory in mice. A natural Abeta oligomer solution containing Abeta monomers, dimers, trimers, and tetramers was derived from the conditioned medium of 7PA2 cells, a cell line that expresses human amyloid precursor protein containing the Val717Phe familial AD mutation. As a control we used 7PA2 conditioned medium from which Abeta oligomers were removed through immunodepletion. Separate groups of mice were injected with Abeta and control solutions through a cannula into the lateral brain ventricle, and subjected to fear conditioning using two tone-shock pairings. One day after fear conditioning, mice were tested for contextual fear memory and tone fear memory in separate retrieval trials. Three experiments were performed. For experiment 1, mice were injected three times: 1 hour before and 3 hours after fear conditioning, and 1 hour before context retrieval. For experiments 2 and 3, mice were injected a single time at 1 hour and 2 hours before fear conditioning respectively. In all three experiments there was no effect on tone fear memory. Injection of Abeta 1 hour before fear conditioning, but not 2 hours before fear conditioning, impaired the formation of a contextual fear memory. In future studies, the acute effect of natural Abeta oligomers on contextual fear memory can be used to identify potential mechanisms and treatments of AD associated memory loss.

  4. Natural Amyloid-Beta Oligomers Acutely Impair the Formation of a Contextual Fear Memory in Mice

    Science.gov (United States)

    Kittelberger, Kara A.; Piazza, Fabrizio; Tesco, Giuseppina; Reijmers, Leon G.

    2012-01-01

    Memory loss is one of the hallmark symptoms of Alzheimer's disease (AD). It has been proposed that soluble amyloid-beta (Abeta) oligomers acutely impair neuronal function and thereby memory. We here report that natural Abeta oligomers acutely impair contextual fear memory in mice. A natural Abeta oligomer solution containing Abeta monomers, dimers, trimers, and tetramers was derived from the conditioned medium of 7PA2 cells, a cell line that expresses human amyloid precursor protein containing the Val717Phe familial AD mutation. As a control we used 7PA2 conditioned medium from which Abeta oligomers were removed through immunodepletion. Separate groups of mice were injected with Abeta and control solutions through a cannula into the lateral brain ventricle, and subjected to fear conditioning using two tone-shock pairings. One day after fear conditioning, mice were tested for contextual fear memory and tone fear memory in separate retrieval trials. Three experiments were performed. For experiment 1, mice were injected three times: 1 hour before and 3 hours after fear conditioning, and 1 hour before context retrieval. For experiments 2 and 3, mice were injected a single time at 1 hour and 2 hours before fear conditioning respectively. In all three experiments there was no effect on tone fear memory. Injection of Abeta 1 hour before fear conditioning, but not 2 hours before fear conditioning, impaired the formation of a contextual fear memory. In future studies, the acute effect of natural Abeta oligomers on contextual fear memory can be used to identify potential mechanisms and treatments of AD associated memory loss. PMID:22238679

  5. Characterization of methacrylate-based composites containing thio-urethane oligomers.

    Science.gov (United States)

    Bacchi, Atais; Nelson, Morgan; Pfeifer, Carmem S

    2016-02-01

    To evaluate the ability of thio-urethane oligomers to improve the properties of restorative composite resins. Oligomers were synthesized by combining 1,6-hexanediol-diissocyante (aliphatic) with pentaerythritol tetra-3-mercaptopropionate (PETMP) or 1,3-bis(1-isocyanato-1-methylethyl)benzene (aromatic) with trimethylol-tris-3-mercaptopropionate (TMP), at 1:2 isocyanate:thiol, leaving pendant thiols. Oligomers were added at 0-20 wt% to BisGMA-TEGDMA (70-30 wt%). Silanated inorganic fillers were added (70 wt%). Materials were photoactivated at 800 mW/cm(2) filtered to 320-500 nm. Near-IR was used to follow degree of methacrylate conversion (DC). Mechanical properties were evaluated in three-point bending with 2 mm × 2 mm × 25 mm bars for flexural strength/modulus and toughness (FS/E, and T) according to ISO 4049, and 2 mm × 5 mm × 25 mm notched specimens for fracture toughness (KIC). Polymerization stress (PS) was measured on the Bioman. Results were analyzed with ANOVA/Tukey's test (α=5%). Significant increase in DC was observed in thio-urethane-containing materials especially for the group with 20 wt% of aliphatic version. Materials composed by oligomers also promoted higher FS, E, and KIC in comparison to controls irrespective of thio-urethane type. A significant increase in toughness was detected by ANOVA, but not distinguished in the groups. The PS was significantly reduced by the presence of thio-urethane for almost all groups. The use of thio-urethane oligomer to compose methacrylate-based restorative composite promote increase in DC, FS, E and KIC while significant reduces PS. A simple additive was shown to reduce stress while increasing convrersion and mechanical properties, mainly fracture toughness. This has he potential of increasing the service life of dental composites, without changing current operatory procedures. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. Distinct Internalization Pathways of Human Amylin Monomers and Its Cytotoxic Oligomers in Pancreatic Cells

    Science.gov (United States)

    Trikha, Saurabh; Jeremic, Aleksandar M.

    2013-01-01

    Toxic human amylin oligomers and aggregates are implicated in the pathogenesis of type 2 diabetes mellitus (TTDM). Although recent studies have shown that pancreatic cells can recycle amylin monomers and toxic oligomers, the exact uptake mechanism and trafficking routes of these molecular forms and their significance for amylin toxicity are yet to be determined. Using pancreatic rat insulinoma (RIN-m5F) beta (β)-cells and human islets as model systems we show that monomers and oligomers cross the plasma membrane (PM) through both endocytotic and non-endocytotic (translocation) mechanisms, the predominance of which is dependent on amylin concentrations and incubation times. At low (≤100 nM) concentrations, internalization of amylin monomers in pancreatic cells is completely blocked by the selective amylin-receptor (AM-R) antagonist, AC-187, indicating an AM-R dependent mechanism. In contrast at cytotoxic (µM) concentrations monomers initially (1 hour) enter pancreatic cells by two distinct mechanisms: translocation and macropinocytosis. However, during the late stage (24 hours) monomers internalize by a clathrin-dependent but AM-R and macropinocytotic independent pathway. Like monomers a small fraction of the oligomers initially enter cells by a non-endocytotic mechanism. In contrast a majority of the oligomers at both early (1 hour) and late times (24 hours) traffic with a fluid-phase marker, dextran, to the same endocytotic compartments, the uptake of which is blocked by potent macropinocytotic inhibitors. This led to a significant increase in extra-cellular PM accumulation, in turn potentiating amylin toxicity in pancreatic cells. Our studies suggest that macropinocytosis is a major but not the only clearance mechanism for both amylin’s molecular forms, thereby serving a cyto-protective role in these cells. PMID:24019897

  7. Natural amyloid-β oligomers acutely impair the formation of a contextual fear memory in mice.

    Directory of Open Access Journals (Sweden)

    Kara A Kittelberger

    Full Text Available Memory loss is one of the hallmark symptoms of Alzheimer's disease (AD. It has been proposed that soluble amyloid-beta (Abeta oligomers acutely impair neuronal function and thereby memory. We here report that natural Abeta oligomers acutely impair contextual fear memory in mice. A natural Abeta oligomer solution containing Abeta monomers, dimers, trimers, and tetramers was derived from the conditioned medium of 7PA2 cells, a cell line that expresses human amyloid precursor protein containing the Val717Phe familial AD mutation. As a control we used 7PA2 conditioned medium from which Abeta oligomers were removed through immunodepletion. Separate groups of mice were injected with Abeta and control solutions through a cannula into the lateral brain ventricle, and subjected to fear conditioning using two tone-shock pairings. One day after fear conditioning, mice were tested for contextual fear memory and tone fear memory in separate retrieval trials. Three experiments were performed. For experiment 1, mice were injected three times: 1 hour before and 3 hours after fear conditioning, and 1 hour before context retrieval. For experiments 2 and 3, mice were injected a single time at 1 hour and 2 hours before fear conditioning respectively. In all three experiments there was no effect on tone fear memory. Injection of Abeta 1 hour before fear conditioning, but not 2 hours before fear conditioning, impaired the formation of a contextual fear memory. In future studies, the acute effect of natural Abeta oligomers on contextual fear memory can be used to identify potential mechanisms and treatments of AD associated memory loss.

  8. Chlorogenic acid in a Nicotiana plumbaginifolia cell suspension.

    Science.gov (United States)

    Gillet; Mesnard; Fliniaux; Monti; Fliniaux

    1999-11-01

    A phenylpropanoid compound has been characterized in a Nicotiana plumbaginifolia cell suspension. This compound has been isolated and purified by semi-preparative reverse phase-high performance liquid chromatography. Its structure has been identified by NMR spectroscopy as 5-O-caffeoylquinic acid, which is chlorogenic acid (CA). The influence of culture conditions on the accumulation of this metabolite by N. plumbaginifolia cell suspensions has been studied. Darkness strongly inhibits the CA accumulation. Moreover, it has been shown that feeding experiments with caffeic acid had a deleterious effect upon the CA content. This one was not influenced by a supplementation with quinic acid.

  9. Causative factors for formation of toxic islet amyloid polypeptide oligomer in type 2 diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Jeong HR

    2015-11-01

    Full Text Available Hye Rin Jeong, Seong Soo A AnDepartment of Bionano Technology, Gachon Medical Research Institute, Gachon University, Gyeonggi-do, Republic of KoreaAbstract: Human islet amyloid polypeptide (h-IAPP is a peptide hormone that is synthesized and cosecreted with insulin from insulin-secreting pancreatic β-cells. Recently, h-IAPP was proposed to be the main component responsible for the cytotoxic pancreatic amyloid deposits in patients with type 2 diabetes mellitus (T2DM. Since the causative factors of IAPP (or amylin oligomer aggregation are not fully understood, this review will discuss the various forms of h-IAPP aggregation. Not all forms of IAPP aggregates trigger the destruction of β-cell function and loss of β-cell mass; however, toxic oligomers do trigger these events. Once these toxic oligomers form under abnormal metabolic conditions in T2DM, they can lead to cell disruption by inducing cell membrane destabilization. In this review, the various factors that have been shown to induce toxic IAPP oligomer formation will be presented, as well as the potential mechanism of oligomer and fibril formation from pro-IAPPs. Initially, pro-IAPPs undergo enzymatic reactions to produce the IAPP monomers, which can then develop into oligomers and fibrils. By this mechanism, toxic oligomers could be generated by diverse pathway components. Thus, the interconnections between factors that influence amyloid aggregation (eg, absence of PC2 enzyme, deamidation, reduction of disulfide bonds, environmental factors in the cell, genetic mutations, copper metal ions, and heparin will be presented. Hence, this review will aid in understanding the fundamental causative factors contributing to IAPP oligomer formation and support studies for investigating novel T2DM therapeutic approaches, such as the development of inhibitory agents for preventing oligomerization at the early stages of diabetic pathology.Keywords: amyloid aggregation, causative factor, IAPP, islet

  10. Synthesis of Cycloveratrylene Macrocycles and Benzyl Oligomers Catalysed by Bentonite under Microwave/Infrared and Solvent-Free Conditions

    Directory of Open Access Journals (Sweden)

    Manuel Salmón

    2013-10-01

    Full Text Available Tonsil Actisil FF, which is a commercial bentonitic clay, promotes the formation of cycloveratrylene macrocycles and benzyl oligomers from the corresponding benzyl alcohols in good yields under microwave heating and infrared irradiation in the absence of solvent in both cases. The catalytic reaction is sensitive to the type of substituent on the aromatic ring. Thus, when benzyl alcohol was substituted with a methylenedioxy, two methoxy or three methoxy groups, a cyclooligomerisation process was induced. Unsubstituted, methyl and methoxy benzyl alcohols yielded linear oligomers. In addition, computational chemistry calculations were performed to establish a validated mechanistic pathway to explain the growth of the obtained linear oligomers.

  11. Accumulation of oligomer-prone α-synuclein exacerbates synaptic and neuronal degeneration in vivo.

    Science.gov (United States)

    Rockenstein, Edward; Nuber, Silke; Overk, Cassia R; Ubhi, Kiren; Mante, Michael; Patrick, Christina; Adame, Anthony; Trejo-Morales, Margarita; Gerez, Juan; Picotti, Paola; Jensen, Poul H; Campioni, Silvia; Riek, Roland; Winkler, Jürgen; Gage, Fred H; Winner, Beate; Masliah, Eliezer

    2014-05-01

    In Parkinson's disease and dementia with Lewy bodies, α-synuclein aggregates to form oligomers and fibrils; however, the precise nature of the toxic α-synuclein species remains unclear. A number of synthetic α-synuclein mutations were recently created (E57K and E35K) that produce species of α-synuclein that preferentially form oligomers and increase α-synuclein-mediated toxicity. We have shown that acute lentiviral expression of α-synuclein E57K leads to the degeneration of dopaminergic neurons; however, the effects of chronic expression of oligomer-prone α-synuclein in synapses throughout the brain have not been investigated. Such a study could provide insight into the possible mechanism(s) through which accumulation of α-synuclein oligomers in the synapse leads to neurodegeneration. For this purpose, we compared the patterns of neurodegeneration and synaptic damage between a newly generated mThy-1 α-synuclein E57K transgenic mouse model that is prone to forming oligomers and the mThy-1 α-synuclein wild-type mouse model (Line 61), which accumulates various forms of α-synuclein. Three lines of α-synuclein E57K (Lines 9, 16 and 54) were generated and compared with the wild-type. The α-synuclein E57K Lines 9 and 16 were higher expressings of α-synuclein, similar to α-synuclein wild-type Line 61, and Line 54 was a low expressing of α-synuclein compared to Line 61. By immunoblot analysis, the higher-expressing α-synuclein E57K transgenic mice showed abundant oligomeric, but not fibrillar, α-synuclein whereas lower-expressing mice accumulated monomeric α-synuclein. Monomers, oligomers, and fibrils were present in α-synuclein wild-type Line 61. Immunohistochemical and ultrastructural analyses demonstrated that α-synuclein accumulated in the synapses but not in the neuronal cells bodies, which was different from the α-synuclein wild-type Line 61, which accumulates α-synuclein in the soma. Compared to non-transgenic and lower-expressing mice, the

  12. Amyloid β oligomers induce interleukin-1β production in primary microglia in a cathepsin B- and reactive oxygen species-dependent manner

    Energy Technology Data Exchange (ETDEWEB)

    Taneo, Jun; Adachi, Takumi [Department of Animal Development and Physiology, Kyoto University, Yoshida-Konoe, Sakyo, Kyoto 606-8501 (Japan); Yoshida, Aiko; Takayasu, Kunio [Responses to Environmental Signals and Stresses, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe, Sakyo, Kyoto, Kyoto 606-8501 (Japan); Takahara, Kazuhiko, E-mail: ktakahar@zoo.zool.kyoto-u.ac.jp [Department of Animal Development and Physiology, Kyoto University, Yoshida-Konoe, Sakyo, Kyoto 606-8501 (Japan); Japan Science and Technology Agency, Core Research for Evolutional Science and Technology (CREST), Tokyo 102-0081 (Japan); Inaba, Kayo [Department of Animal Development and Physiology, Kyoto University, Yoshida-Konoe, Sakyo, Kyoto 606-8501 (Japan); Japan Science and Technology Agency, Core Research for Evolutional Science and Technology (CREST), Tokyo 102-0081 (Japan)

    2015-03-13

    Amyloid β (Aβ) peptide, a causative agent of Alzheimer's disease, forms two types of aggregates: oligomers and fibrils. These aggregates induce inflammatory responses, such as interleukin-1β (IL-1β) production by microglia, which are macrophage-like cells located in the brain. In this study, we examined the effect of the two forms of Aβ aggregates on IL-1β production in mouse primary microglia. We prepared Aβ oligomer and fibril from Aβ (1–42) peptide in vitro. We analyzed the characteristics of these oligomers and fibrils by electrophoresis and atomic force microscopy. Interestingly, Aβ oligomers but not Aβ monomers or fibrils induced robust IL-1β production in the presence of lipopolysaccharide. Moreover, Aβ oligomers induced endo/phagolysosome rupture, which released cathepsin B into the cytoplasm. Aβ oligomer-induced IL-1β production was inhibited not only by the cathepsin B inhibitor CA-074-Me but also by the reactive oxygen species (ROS) inhibitor N-acetylcysteine. Random chemical crosslinking abolished the ability of the oligomers to induce IL-1β. Thus, multimerization and fibrillization causes Aβ oligomers to lose the ability to induce IL-1β. These results indicate that Aβ oligomers, but not fibrils, induce IL-1β production in primary microglia in a cathepsin B- and ROS-dependent manner. - Highlights: • We prepared amyloid β (Aβ) fibrils with minimum contamination of Aβ oligomers. • Primary microglia (MG) produced IL-1β in response to Aβ oligomers, but not fibrils. • Only Aβ oligomers induced leakage of cathepsin B from endo/phagolysosomes. • IL-1β production in response to Aβ oligomers depended on both cathepsin B and ROS. • Crosslinking reduced the ability of the Aβ oligomers to induce IL-1β from MG.

  13. Dietary Consumption of Phenolic Acids and Prostate Cancer: A Case-Control Study in Sicily, Southern Italy

    Directory of Open Access Journals (Sweden)

    Giorgio Ivan Russo

    2017-12-01

    Full Text Available Dietary polyphenols gained the interest of the scientific community due to their wide content in a variety of plant-derived foods and beverages commonly consumed, such as fruits, vegetables, coffee, tea, and cocoa. We aimed to investigate whether there was an association between dietary phenolic acid consumption and prostate cancer (PCa in South Italy. We conducted a population-based case-control study from January 2015 to December 2016 in a single institution of the municipality of Catania, southern Italy (Registration number: 41/2015. Patients with elevated PSA and/or suspicious PCa underwent transperineal prostate biopsy. A total of 118 histopathological-verified PCa cases were collected and a total of 222 controls were selected from a sample of 2044 individuals. Dietary data were collected by using two food frequency questionnaires and data on the phenolic acids content in foods was obtained from the Phenol-Explorer database (www.phenol-explorer.eu. Association between dietary intake of phenolic acids and PCa was calculated through logistic regression analysis. We found lower levels of caffeic acid (2.28 mg/day vs. 2.76 mg/day; p < 0.05 and ferulic acid (2.80 mg/day vs. 4.04 mg/day; p < 0.01 in PCa when compared to controls. The multivariate logistic regression showed that both caffeic acid (OR = 0.32; p < 0.05 and ferulic acid (OR = 0.30; p < 0.05 were associated with reduced risk of PCa. Higher intake of hydroxybenzoic acids and caffeic acids were associated with lower risk of advanced PCa. High intake of caffeic acid and ferulic acid may be associated with reduced risk of PCa.

  14. Dietary Consumption of Phenolic Acids and Prostate Cancer: A Case-Control Study in Sicily, Southern Italy.

    Science.gov (United States)

    Russo, Giorgio Ivan; Campisi, Daniele; Di Mauro, Marina; Regis, Federica; Reale, Giulio; Marranzano, Marina; Ragusa, Rosalia; Solinas, Tatiana; Madonia, Massimo; Cimino, Sebastiano; Morgia, Giuseppe

    2017-12-05

    Dietary polyphenols gained the interest of the scientific community due to their wide content in a variety of plant-derived foods and beverages commonly consumed, such as fruits, vegetables, coffee, tea, and cocoa . We aimed to investigate whether there was an association between dietary phenolic acid consumption and prostate cancer (PCa) in South Italy. We conducted a population-based case-control study from January 2015 to December 2016 in a single institution of the municipality of Catania, southern Italy (Registration number: 41/2015). Patients with elevated PSA and/or suspicious PCa underwent transperineal prostate biopsy. A total of 118 histopathological-verified PCa cases were collected and a total of 222 controls were selected from a sample of 2044 individuals. Dietary data were collected by using two food frequency questionnaires and data on the phenolic acids content in foods was obtained from the Phenol-Explorer database (www.phenol-explorer.eu). Association between dietary intake of phenolic acids and PCa was calculated through logistic regression analysis. We found lower levels of caffeic acid (2.28 mg/day vs. 2.76 mg/day; p < 0.05) and ferulic acid (2.80 mg/day vs. 4.04 mg/day; p < 0.01) in PCa when compared to controls. The multivariate logistic regression showed that both caffeic acid (OR = 0.32; p < 0.05) and ferulic acid (OR = 0.30; p < 0.05) were associated with reduced risk of PCa. Higher intake of hydroxybenzoic acids and caffeic acids were associated with lower risk of advanced PCa. High intake of caffeic acid and ferulic acid may be associated with reduced risk of PCa.

  15. Microflora dynamics in earthworms casts in an artificial soil (biosynthesol containing lactic acid oligomers

    Directory of Open Access Journals (Sweden)

    Alauzet Nathalie

    2001-01-01

    Full Text Available Studies were performed to appreciate the presence of micro-organisms able to degrade OLA, in earthworms casts or in the surroundings. Worms were grown in biosynthesol, an artificial soil. The counting of bacteria and fungi in earthworms casts and in biosynthesol without earthworms suggested that earthworms ate some of the micro-organisms. The main filamentous fungi genera found were Aspergillus, Trichoderma, Fusarium and Penicillium. Previous results in the literature have shown that some species from the Aspergillus and Fusarium genera were able to degrade OLA and other aliphatic esters. It could be suggested that these two genera and some bacteria were responsible for the pre-degradation of OLA, and that earthworms might eat them.

  16. High-affinity triplex targeting of double stranded DNA using chemically modified peptide nucleic acid oligomers

    DEFF Research Database (Denmark)

    Hansen, Mads E; Bentin, Thomas; Nielsen, Peter E

    2009-01-01

    While sequence-selective dsDNA targeting by triplex forming oligonucleotides has been studied extensively, only very little is known about the properties of PNA-dsDNA triplexes-mainly due to the competing invasion process. Here we show that when appropriately modified using pseudoisocytosine subs...

  17. Oligomers, organosulfates, and nitrooxy organosulfates in rainwater identified by ultra-high resolution electrospray ionization FT-ICR mass spectrometry

    Directory of Open Access Journals (Sweden)

    K. E. Altieri

    2009-04-01

    Full Text Available Wet deposition is an important removal mechanism for atmospheric organic matter, and a potentially important input for receiving ecosystems, yet less than 50% of rainwater organic matter is considered chemically characterized. Precipitation samples collected in New Jersey, USA, were analyzed by negative ion ultra-high resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS. Elemental compositions of 552 unique molecular species were determined in the mass range 50–500 Da in the rainwater. Four main groups of organic compounds were identified: compounds containing carbon, hydrogen, and oxygen (CHO only, sulfur (S containing CHOS compounds, nitrogen (N containing CHON compounds, and S- and N- containing CHONS compounds. Organic acids commonly identified in precipitation were detected in the rainwater. Within the four main groups of compounds detected in the rainwater, oligomers, organosulfates, and nitrooxy-organosulfates were assigned based on elemental formula comparisons. The majority of the compounds identified are products of atmospheric reactions and are known contributors to secondary organic aerosol (SOA formed from gas phase, aerosol phase, and in-cloud reactions in the atmosphere. It is suggested that the large uncharacterized component of SOA is the main contributor to the large uncharacterized component of rainwater organic matter.

  18. Detection of Aspergillus fumigatus pulmonary fungal infections in mice with 99mTc-labeled MORF oligomers targeting ribosomal RNA

    International Nuclear Information System (INIS)

    Wang Yuzhen; Chen Ling; Liu Xinrong; Cheng Dengfeng; Liu Guozheng; Liu Yuxia; Dou Shuping; Hnatowich, Donald J.; Rusckowski, Mary

    2013-01-01

    Purpose: Invasive aspergillosis is a major cause of infectious morbidity and mortality in immunocompromised patients. The fungus Aspergillus fumigatus (A. fumigatus) is the primary causative agent of invasive aspergillosis. However, A. fumigatus infections remain difficult to diagnose particularly in the early stages due to the lack of a rapid, sensitive and specific diagnostic approach. In this study, we investigated 99m Tc labeled MORF oligomers targeting fungal ribosomal RNA (rRNA) for the imaging detection of fungal infections. Procedures: Three phosphorodiamidate morpholino (MORF) oligomer (a DNA analogue) probes were designed: AGEN, complementary to a sequence of the fungal 28S ribosomal RNA (rRNA) of Aspergillus, as a genus-specific probe; AFUM, complementary to the 28S rRNA sequence of A. fumigatus, as a fungus species-specific probe; and cMORF, irrelevant to all fungal species, as a control probe. The probes were conjugated with Alexa Fluor 633 carboxylic acid succinimidyl ester (AF633) for fluorescence imaging or with NHS-mercaptoacetyl triglycine (NHS-MAG3) for nuclear imaging with 99m Tc and then evaluated in vitro and in vivo. Results: The specific binding of AGEN and AFUM to fungal total RNA was confirmed by dot blot hybridization while specific binding of AGEN and AFUM in fixed and live A. fumigatus was demonstrated by both fluorescent in situ hybridization (FISH) analysis and accumulation in live cells. SPECT imaging of BALB/c mice with pulmonary A. fumigatus infections and administered 99m Tc labeled AGEN and AFUM showed immediate and obvious accumulation in the infected lungs, while no significant accumulation of the control 99m Tc-cMORF in the infected lung was observed. Compared to non-infected mice, with sacrifice at 1 h, the accumulation of 99m Tc-AGEN and 99m Tc-AFUM in the lungs of mice infected with A. fumigatus was 2 and 2.7 fold higher respectively. Conclusions: In vivo targeting fungal ribosomal RNA with 99m Tc labeled MORF probes AGEN

  19. Detergent-Resistant Membrane Microdomains Facilitate Ib Oligomer Formation and Biological Activity of Clostridium perfringens Iota-Toxin

    National Research Council Canada - National Science Library

    Hale, Martha

    2004-01-01

    ...) were extracted with cold Triton X-100. Western blotting revealed that Ib oligomers localized in DRMs extracted from Vero, but not MRC-5, cells while monomeric Ib was detected in the detergent-soluble fractions of both cell types...

  20. Effects of the Aqueous Extract from Tabebuia roseoalba and Phenolic Acids on Hyperuricemia and Inflammation

    Directory of Open Access Journals (Sweden)

    Zilma Schimith Ferraz-Filha

    2017-01-01

    Full Text Available Tabebuia species (Bignoniaceae have long been used in folk medicine as anti-inflammatory, antirheumatic, antimicrobial, and antitumor. The aim of this study was to investigate if aqueous extract from the leaves (AEL of Tabebuia roseoalba (Ridl. Sandwith, Bignoniaceae, and its constituents could be useful to decrease serum uric acid levels and restrain the gout inflammatory process. HPLC analysis identified caffeic acid and chlorogenic acid in AEL. Antihyperuricemic effects and inhibition of liver XOD (xanthine oxidoreductase by AEL and identified compounds were evaluated in hyperuricemic mice. Anti-inflammatory activity was evaluated on MSU (monosodium urate crystal-induced paw edema. In addition, AEL antioxidant activity in vitro was evaluated. AEL, caffeic, and chlorogenic acids were able to reduce serum uric acid levels in hyperuricemic mice probably through inhibition of liver xanthine oxidase activity and significantly decreased the paw edema induced by MSU crystals. AEL showed significant antioxidant activity in all evaluated assays. The results show that the AEL of Tabebuia roseoalba can be a promising agent for treatment for gout and inflammatory diseases. We suggest that caffeic and chlorogenic acids may be responsible for the activities demonstrated by the species.

  1. Rapamycin-induced oligomer formation system of FRB-FKBP fusion proteins.

    Science.gov (United States)

    Inobe, Tomonao; Nukina, Nobuyuki

    2016-07-01

    Most proteins form larger protein complexes and perform multiple functions in the cell. Thus, artificial regulation of protein complex formation controls the cellular functions that involve protein complexes. Although several artificial dimerization systems have already been used for numerous applications in biomedical research, cellular protein complexes form not only simple dimers but also larger oligomers. In this study, we showed that fusion proteins comprising the induced heterodimer formation proteins FRB and FKBP formed various oligomers upon addition of rapamycin. By adjusting the configuration of fusion proteins, we succeeded in generating an inducible tetramer formation system. Proteins of interest also formed tetramers by fusing to the inducible tetramer formation system, which exhibits its utility in a broad range of biological applications. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  2. QIAD assay for quantitating a compound’s efficacy in elimination of toxic Aβ oligomers

    Science.gov (United States)

    Brener, Oleksandr; Dunkelmann, Tina; Gremer, Lothar; van Groen, Thomas; Mirecka, Ewa A.; Kadish, Inga; Willuweit, Antje; Kutzsche, Janine; Jürgens, Dagmar; Rudolph, Stephan; Tusche, Markus; Bongen, Patrick; Pietruszka, Jörg; Oesterhelt, Filipp; Langen, Karl-Josef; Demuth, Hans-Ulrich; Janssen, Arnold; Hoyer, Wolfgang; Funke, Susanne A.; Nagel-Steger, Luitgard; Willbold, Dieter

    2015-01-01

    Strong evidence exists for a central role of amyloid β-protein (Aβ) oligomers in the pathogenesis of Alzheimer’s disease. We have developed a fast, reliable and robust in vitro assay, termed QIAD, to quantify the effect of any compound on the Aβ aggregate size distribution. Applying QIAD, we studied the effect of homotaurine, scyllo-inositol, EGCG, the benzofuran derivative KMS88009, ZAβ3W, the D-enantiomeric peptide D3 and its tandem version D3D3 on Aβ aggregation. The predictive power of the assay for in vivo efficacy is demonstrated by comparing the oligomer elimination efficiency of D3 and D3D3 with their treatment effects in animal models of Alzheimer´s disease. PMID:26394756

  3. Liquid Crystalline Thermosets from Ester, Ester-imide, and Ester-amide Oligomers

    Science.gov (United States)

    Dingemans, Theodorus J. (Inventor); Weiser, Erik S. (Inventor); St. Clair, Terry L. (Inventor)

    2009-01-01

    Main chain thermotropic liquid crystal esters, ester-imides, and ester-amides were prepared from AA, BB, and AB type monomeric materials and end-capped with phenylacetylene, phenylmaleimide, or nadimide reactive end-groups. The end-capped liquid crystal oligomers are thermotropic and have, preferably, molecular weights in the range of approximately 1000-15,000 grams per mole. The end-capped liquid crystaloligomers have broad liquid crystalline melting ranges and exhibit high melt stability and very low melt viscosities at accessible temperatures. The end-capped liquid crystal oli-gomers are stable forup to an hour in the melt phase. They are highly processable by a variety of melt process shape forming and blending techniques. Once processed and shaped, the end-capped liquid crystal oigomers were heated to further polymerize and form liquid crystalline thermosets (LCT). The fully cured products are rubbers above their glass transition temperatures.

  4. "Nail" and "comb" effects of cholesterol modified NIPAm oligomers on cancer targeting liposomes

    KAUST Repository

    Li, Wengang; Deng, Lin; Moosa, Basem; Wang, Guangchao; Mashat, Afnan; Khashab, Niveen M.

    2014-01-01

    Thermosensitive liposomes are a promising approach to controlled release and reduced drug cytotoxicity. Low molecular weight N-isopropylacrylamide (NIPAm) oligomers (NOs) with different architectures (main chain NOs (MCNOs) and side chain NOs (SCNOs)) were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and radical polymerization and then separately used to prepare thermosensitive liposomes. A more controlled and enhanced release was observed for both NO liposomes compared to pristine ones. Two release mechanisms depending on the oligomer architecture, namely "nail" for MCNOs and "comb" for SCNOs, are proposed. In addition to thermosensitivity, the cancer targeting property of NO liposomes was achieved by further biotinylation of the delivery system. © The Royal Society of Chemistry.

  5. Protein misfolding cyclic amplification induces the conversion of recombinant prion protein to PrP oligomers causing neuronal apoptosis.

    Science.gov (United States)

    Yuan, Zhen; Yang, Lifeng; Chen, Baian; Zhu, Ting; Hassan, Mohammad Farooque; Yin, Xiaomin; Zhou, Xiangmei; Zhao, Deming

    2015-06-01

    The formation of neurotoxic prion protein (PrP) oligomers is thought to be a key step in the development of prion diseases. Recently, it was determined that the sonication and shaking of recombinant PrP can convert PrP monomers into β-state oligomers. Herein, we demonstrate that β-state oligomeric PrP can be generated through protein misfolding cyclic amplification from recombinant full-length hamster, human, rabbit, and mutated rabbit PrP, and that these oligomers can be used for subsequent research into the mechanisms of PrP-induced neurotoxicity. We have characterized protein misfolding cyclic amplification-induced monomer-to-oligomer conversion of PrP from three species using western blotting, circular dichroism, size-exclusion chromatography, and resistance to proteinase K (PK) digestion. We have further shown that all of the resulting β-oligomers are toxic to primary mouse cortical neurons independent of the presence of PrP(C) in the neurons, whereas the corresponding monomeric PrP were not toxic. In addition, we found that this toxicity is the result of oligomer-induced apoptosis via regulation of Bcl-2, Bax, and caspase-3 in both wild-type and PrP(-/-) cortical neurons. It is our hope that these results may contribute to our understanding of prion transformation within the brain. We found that β-state oligomeric PrPs can be generated through protein misfolding cyclic amplification (PMCA) from recombinant full-length hamster, human, rabbit, and mutated rabbit PrP. β-oligomers are toxic to primary mouse cortical neurons independent of the presence of PrP(C) in the neurons, while the corresponding monomeric PrPs were not toxic. This toxicity is the result of oligomers-induced apoptosis via regulation of Bcl-2, Bax, and caspase-3. These results may contribute to our understanding of prion transformation within the brain. © 2015 International Society for Neurochemistry.

  6. Rationally designed turn promoting mutation in the amyloid-β peptide sequence stabilizes oligomers in solution.

    Directory of Open Access Journals (Sweden)

    Jayakumar Rajadas

    Full Text Available Enhanced production of a 42-residue beta amyloid peptide (Aβ(42 in affected parts of the brain has been suggested to be the main causative factor for the development of Alzheimer's Disease (AD. The severity of the disease depends not only on the amount of the peptide but also its conformational transition leading to the formation of oligomeric amyloid-derived diffusible ligands (ADDLs in the brain of AD patients. Despite being significant to the understanding of AD mechanism, no atomic-resolution structures are available for these species due to the evanescent nature of ADDLs that hinders most structural biophysical investigations. Based on our molecular modeling and computational studies, we have designed Met35Nle and G37p mutations in the Aβ(42 peptide (Aβ(42Nle35p37 that appear to organize Aβ(42 into stable oligomers. 2D NMR on the Aβ(42Nle35p37 peptide revealed the occurrence of two β-turns in the V24-N27 and V36-V39 stretches that could be the possible cause for the oligomer stability. We did not observe corresponding NOEs for the V24-N27 turn in the Aβ(21-43Nle35p37 fragment suggesting the need for the longer length amyloid peptide to form the stable oligomer promoting conformation. Because of the presence of two turns in the mutant peptide which were absent in solid state NMR structures for the fibrils, we propose, fibril formation might be hindered. The biophysical information obtained in this work could aid in the development of structural models for toxic oligomer formation that could facilitate the development of therapeutic approaches to AD.

  7. Single-molecule studies of oligomer extraction and uptake of dyes in poly(dimethylsiloxane) films.

    Science.gov (United States)

    Lange, Jeffrey J; Collinson, Maryanne M; Culbertson, Christopher T; Higgins, Daniel A

    2009-12-15

    Single-molecule microscopic methods were used to probe the uptake, mobility, and entrapment of dye molecules in cured poly(dimethylsiloxane) (PDMS) films as a function of oligomer extraction. The results are relevant to the use of PDMS in microfluidic separations, pervaporation, solid-phase microextraction, and nanofiltration. PDMS films were prepared by spin-casting dilute solutions of Sylgard 184 onto glass coverslips, yielding approximately 1.4 microm thick films after curing. Residual oligomers were subsequently extracted from the films by "spin extraction". In this procedure, 200 microL aliquots of isopropyl alcohol were repeatedly dropped onto the film surface and spun off at 2000 rpm. Samples extracted 5, 10, 20, and 40 times were investigated. Dye molecules were loaded into these films by spin-casting nanomolar dye solutions onto the films. Both neutral perylene diimide (N,N'-bis(butoxypropyl)perylene-3,4,9,10-tetracarboxylic diimide) and cationic rhodamine 6G (R6G) dyes were employed. The films were imaged by confocal fluorescence microscopy. The images obtained depict nonzero populations of fixed and mobile molecules in all films. Cross-correlation methods were used to quantitatively determine the population of fixed molecules in a given region, while a Bayesian burst analysis was used to obtain the total population of molecules. The results show that the total amount of dye loaded increases with increased oligomer extraction, while the relative populations of fixed and mobile molecules decrease and increase, respectively. Bulk R6G data also show greater dye loading with increased oligomer extraction.

  8. Polyethylenimine-modified Pluronics (PCMs) Improve Morpholino Oligomer Delivery in Cell Culture and Dystrophic mdx Mice

    OpenAIRE

    Wang, Mingxing; Wu, Bo; Lu, Peijuan; Cloer, Caryn; Tucker, Jay D; Lu, Qilong

    2012-01-01

    We investigated a series of small-sized polyethylenimine (PEI, 0.8/1.2 k)-conjugated pluronic copolymers (PCMs) for their potential to enhance delivery of an antisense phosphorodiamidate morpholino oligomer (PMO) in vitro and in dystrophic mdx mice. PCM polymers containing pluronics of molecular weight (Mw) ranging 2–6 k, with hydrophilic-lipophilic balance (HLB) 7–23, significantly enhanced PMO-induced exon-skipping in a green fluorescent protein (GFP) reporter-based myoblast culture system....

  9. Intrahippocampal Administration of Amyloid-β1–42 Oligomers Acutely Impairs Spatial Working Memory, Insulin Signaling, and Hippocampal Metabolism

    Science.gov (United States)

    Pearson-Leary, Jiah; McNay, Ewan C.

    2017-01-01

    Increasing evidence suggests that abnormal brain accumulation of amyloid-β1–42 (Aβ1–42) oligomers plays a causal role in Alzheimer’s disease (AD), and in particular may cause the cognitive deficits that are the hallmark of AD. In vitro, Aβ1–42 oligomers impair insulin signaling and suppress neural functioning. We previously showed that endogenous insulin signaling is an obligatory component of normal hippocampal function, and that disrupting this signaling led to a rapid impairment of spatial working memory, while delivery of exogenous insulin to the hippocampus enhanced both memory and metabolism; diet-induced insulin resistance both impaired spatial memory and prevented insulin from increasing metabolism or cognitive function. Hence, we tested the hypothesis that Aβ1–42 oligomers could acutely impair hippocampal metabolic and cognitive processes in vivo in the rat. Our findings support this hypothesis: Aβ1–42 oligomers impaired spontaneous alternation behavior while preventing the task-associated dip in hippocampal ECF glucose observed in control animals. In addition, Aβ1–42 oligomers decreased plasma membrane translocation of the insulin-sensitive glucose transporter 4 (GluT4), and impaired insulin signaling as measured by phosphorylation of Akt. These data show in vivo that Aβ1–42 oligomers can rapidly impair hippocampal cognitive and metabolic processes, and provide support for the hypothesis that elevated Aβ1–42 leads to cognitive impairment via interference with hippocampal insulin signaling. PMID:22430529

  10. Effect of phenolic oligomer on adhesion of poly (ethylene terephthalate) film laminated steel sheets by Electron Beam Curing method

    International Nuclear Information System (INIS)

    Masuhara, Kenichi; Mori, Koji; Koshiishi, Kenji; Sasaki, Takashi.

    1995-01-01

    Adhesion of poly (ethylene terephthalate) film by Electron Beam Curing (EBC) method which can be thought as an energy-saving process was studied for the purpose of bestowing economically design and distinctness of image on thermosetting high molecular weight polyester precoated steel sheets. Adhesion of EB curable resins onto metal is generally poor. In this report, addition of EB curable phenolic resole oligomer with bifunctional acrylates to the top coat used for precoated steel was studied in order to increase the adhesion of an EB curable adhesive, and it was found that the phenolic oligomer is tremendously effective for the improvement of adhesion. The reasons why the phenolic oligomer provides excellent adhesion were 1) elongation at break of the top coat to which the phenolic oligomer is added is little decreased by EB irradiation, and the formability does not reduce. 2) As the phenolic oligomer is unevenly distributed to the surface layer of the top coat, it is suggested that the contact frequency of the phenolic oligomer to the EB curable adhesive is so high that graft polymerization between them is liable to occur. (author)

  11. NEXAFS characterization of DNA components and molecular-orientation of surface-bound DNA oligomers

    International Nuclear Information System (INIS)

    Samuel, Newton T.; Lee, C.-Y.; Gamble, Lara J.; Fischer, Daniel A.; Castner, David G.

    2006-01-01

    Single stranded DNA oligomers (ssDNA) immobilized onto solid surfaces forms the basis for several biotechnological applications such as DNA microarrays, affinity separations, and biosensors. Surface structure of Surface-bound oligomers is expected to significantly influence their biological activity and interactions with the environment. In this study near-edge X-ray absorption fine structure spectroscopy (NEXAFS) is used to characterize the components of DNA (nucleobases, nucleotides and nucleosides) and the orientation information of surface-bound ssDNA. The K-edges of carbon, nitrogen and oxygen have spectra with features that are characteristic of the different chemical species present in the nucleobases of DNA. The effect of addition of the DNA sugar and phosphate components on the NEXAFS K-edge spectra was also investigated. The polarization-dependent nitrogen K-edge NEXAFS data show significant changes for different orientations of surface bound ssDNA. These results establish NEXAFS as a powerful technique for chemical and structural characterization of surface-bound DNA oligomers

  12. Benzothienobenzothiophene-based conjugated oligomers as semiconductors for stable organic thin-film transistors.

    Science.gov (United States)

    Yu, Han; Li, Weili; Tian, Hongkun; Wang, Haibo; Yan, Donghang; Zhang, Jingping; Geng, Yanhou; Wang, Fosong

    2014-04-09

    Two benzothienobenzothiophene (BTBT)-based conjugated oligomers, i.e., 2,2'-bi[1]benzothieno[3,2-b][1]benzothiophene (1) and 5,5'-bis([1]benzothieno[3,2-b][1]benzothiophen-2-yl)-2,2'-bithiophene (2), were prepared and characterized. Both oligomers exhibit excellent thermal stability, with 5% weight-loss temperatures (T(L)) above 370 °C; no phase transition was observed before decomposition. The highest occupied molecular orbital (HOMO) levels of 1 and 2 are -5.3 and -4.9 eV, respectively, as measured by ultraviolet photoelectron spectroscopy. Thin-film X-ray diffraction and atomic force microscopy characterizations indicate that both oligomers form highly crystalline films with large domain sizes on octadecyltrimethoxysilane-modified substrates. Organic thin-film transistors with top-contact and bottom-gate geometry based on 1 and 2 exhibited mobilities up to 2.12 cm(2)/V·s for 1 and 1.39 cm(2)/V·s for 2 in an ambient atmosphere. 1-based devices exhibited great air and thermal stabilities, as evidenced by the slight performance degradation after 2 months of storage under ambient conditions and after thermal annealing at temperatures below 250 °C.

  13. Dynamics in coarse-grained models for oligomer-grafted silica nanoparticles

    KAUST Repository

    Hong, Bingbing

    2012-01-01

    Coarse-grained models of poly(ethylene oxide) oligomer-grafted nanoparticles are established by matching their structural distribution functions to atomistic simulation data. Coarse-grained force fields for bulk oligomer chains show excellent transferability with respect to chain lengths and temperature, but structure and dynamics of grafted nanoparticle systems exhibit a strong dependence on the core-core interactions. This leads to poor transferability of the core potential to conditions different from the state point at which the potential was optimized. Remarkably, coarse graining of grafted nanoparticles can either accelerate or slowdown the core motions, depending on the length of the grafted chains. This stands in sharp contrast to linear polymer systems, for which coarse graining always accelerates the dynamics. Diffusivity data suggest that the grafting topology is one cause of slower motions of the cores for short-chain oligomer-grafted nanoparticles; an estimation based on transition-state theory shows the coarse-grained core-core potential also has a slowing-down effect on the nanoparticle organic hybrid materials motions; both effects diminish as grafted chains become longer. © 2012 American Institute of Physics.

  14. Tumor delivery of antisense oligomer using trastuzumab within a streptavidin nanoparticle

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi [University of Massachusetts Medical School, Division of Nuclear Medicine, Department of Radiology, Worcester, MA (United States); Yale University, Yale PET Center, Department of Diagnostic Radiology, New Haven, CT (United States); Liu, Xinrong; Chen, Ling; Cheng, Dengfeng; Rusckowski, Mary [University of Massachusetts Medical School, Division of Nuclear Medicine, Department of Radiology, Worcester, MA (United States); Hnatowich, Donald J. [University of Massachusetts Medical School, Division of Nuclear Medicine, Department of Radiology, Worcester, MA (United States); Umass Medical School, Department of Radiology, Worcester, MA (United States)

    2009-12-15

    Trastuzumab (Herceptin trademark) is often internalized following binding to Her2+ tumor cells. The objective of this study was to investigate whether trastuzumab can be used as a specific carrier to deliver antisense oligomers into Her2+ tumor cells both in vitro and in vivo. A biotinylated MORF oligomer antisense to RhoC mRNA and its biotinylated sense control were labeled with either lissamine for fluorescence detection or {sup 99m}Tc for radioactivity detection and were linked to biotinylated trastuzumab via streptavidin. The nanoparticles were studied in SUM190 (RhoC+, Her2+) study and SUM149 (RhoC+, Her2-) control cells in culture and as xenografts in mice. As evidence of unimpaired Her2+ binding of trastuzumab within the nanoparticle, accumulations were clearly higher in SUM190 compared to SUM149 cells and, by whole-body imaging, targeting of SUM190 tumor was similar to that expected for a radiolabeled trastuzumab. As evidence of internalization, fluorescence microscopy images of cells grown in culture and obtained from xenografts showed uniform cytoplasm distribution of the lissamine-MORF. An invasion assay showed decreased RhoC expression in SUM190 cells when incubated with the antisense MORF nanoparticles at only 100 nM. Both in cell culture and in animals, the nanoparticle with trastuzumab as specific carrier greatly improved tumor delivery of the antisense oligomer against RhoC mRNA into tumor cells overexpressing Her2 and may be of general utility. (orig.)

  15. Computational Design of High-χ Block Oligomers for Accessing 1 nm Domains.

    Science.gov (United States)

    Chen, Qile P; Barreda, Leonel; Oquendo, Luis E; Hillmyer, Marc A; Lodge, Timothy P; Siepmann, J Ilja

    2018-05-22

    Molecular dynamics simulations are used to design a series of high-χ block oligomers (HCBOs) that can self-assemble into a variety of mesophases with domain sizes as small as 1 nm. The exploration of these oligomers with various chain lengths, volume fractions, and chain architectures at multiple temperatures reveals the presence of ordered lamellae, perforated lamellae, and hexagonally packed cylinders. The achieved periods are as small as 3.0 and 2.1 nm for lamellae and cylinders, respectively, which correspond to polar domains of approximately 1 nm. Interestingly, the detailed phase behavior of these oligomers is distinct from that of either solvent-free surfactants or block polymers. The simulations reveal that the behavior of these HCBOs is a product of an interplay between both "surfactant factors" (headgroup interactions, chain flexibility, and interfacial curvature) and "block polymer factors" (χ, chain length N, and volume fraction f). This insight promotes the understanding of molecular features pivotal for mesophase formation at the sub-5 nm length scale, which facilitates the design of HCBOs tailored toward particular desired morphologies.

  16. Simulations of absorption spectra of conjugated oligomers: role of planar conformation and aggregation in condensed phase

    Science.gov (United States)

    Yuan, Xiang-Ai; Wen, Jin; Zheng, Dong; Ma, Jing

    2018-04-01

    This Review highlights the structure/property relationship underlying the morphology modulation through various factors towards the exploration of light-absorbing materials for efficient utilisation of solar power. Theoretical study using a combination of molecular dynamics imulations and the time-dependent density functional theory demonstrated that the planarity plays an important role in tuning spectral properties of oligomer aggregates. The aggregation-induced blue-shift in absorption spectra of oligothiophenes and the red-shift for oligofluorenols were rationalised in a unified way from the reduced (and increased) content of planar conformations in molecular aggregates. The planarity versus non-planarity of oligomers can be modulated by introduction of alkyl side chain or steric bulky substituents. The substitution with various groups in the ortho-position of azobenzene leads to the distorted backbone, breaking symmetry, and hence the red-shift in spectra, expanding the application in biological systems with visible light absorption. The donor-acceptor substituent groups in conjugated oligomers can increase the degree of planarity, electron delocalisation and polarisation, and charge separation, giving rise to the red-shift in spectra and enhancement in polarisability and charge mobility for device applications. The solvent dependent and pH-sensitive properties and intramolecular hydrogen bonds also caused the shift of absorption spectra with the appearance of planar conformers.

  17. KARAKTERISASI ENZIM KITOSANASE DAR] ISOLAT BAKTERI KPU 2123 DAN APLIKASINYA UNTUK PRODUKS1 OLIGOMER KITOSAN

    Directory of Open Access Journals (Sweden)

    Yusro Nuri Fawzya

    2009-06-01

    Full Text Available Penelitian ini merupakan sebagian dari rangkaian penelitian mengenai eksplorasi enzim kitinolitik dari mikroba lingkungan laut, khususnya dari limbah udang. Tujuan penelitian ini adalah untuk mengidentifikasi isolat bakteri KPU 2123 dari limbah udang, mengkarakterisasi dan mengaplikasikan enzim kitosanase yang dihasilkan oleh bakteri tersebut untuk produksi oligomer kitosan dan menguji bioaktivitas oligomer kitosan tersebut sebagai antitumor dan antibakteri. Karakterisasi enzim dilakukan dengan menguji aktivitas enzim pada berbagai suhu dan pH. Selain itu juga ditentukan besarnya aktivitas yang tersisa setelah enzim diinkubasi pada suhu dan lama waktu tertentu. Pengaruh ion logam terhadap aktivitas enzim juga dilihat dengan mereaksikan enzim dengan 1 mM ion logam dalam bentuk larutan khlorida. Hasil penelitian menunjukkan bahwa berdasarkan analisis gen 16S-rRNA, isolat bakteri KPU 2123 memiliki kemiripan 95% dengan Stanotrophomonas maltophilia. Enzim kitosanase dari isolat ini bekerja optimal pada suhu 50 ºC dan pH 6. Enzim ini cukup stabil pada suhu 37 ºC selama 120 menit. Penambahan ion logam berpengaruh terhadap aktivitas enzim. Ion logam Zn²+ (sebagai garam klorida 1 mM menghambat 100% aktivitas enzim tersebut. Penggunaan enzim kitosanase dalam menghidrolisis substrat kitosan, menghasilkan oligomer kitosan yang mengandung tetramer, pentamer dan heksamer Oligor kitosan tersebut mampu menghambat pertumbuhan bakteri Staphylococcus aureus sebesar 10,06% dan dapat menyebabkan kematian sel HeLa dengan LC50 pada dosis 120 ppm.

  18. Excitations and optical properties of phenylene-based conjugated polymers and oligomers

    Science.gov (United States)

    Brazovskii, S.; Kirova, N.; Bishop, A. R.; Klimov, V.; McBranch, D.; Barashkov, N. N.; Ferraris, J. P.

    1998-01-01

    We present a combined experimental and theoretical study of the ground and photoexcited optical properties of a model oligomer of PPV, MEH-DSB. Our theoretical picture is based upon a band description of electronic states of PPV oligomers, while invoking corrections from Coulomb interactions. The necessary discrete energy levels at low and intermediate energies appear naturally, in addition to the lower energy delocalized states. On this basis we identify the most important features in direct optical absorption for both high (4-6 eV) and low (2-4 eV) photon energies as well as in photoinduced absorption (PA) and stimulated photoemissions (SE) in MEH-DSB solutions, which represent the limit of noninteracting oligomers. While in agreement with previous interpretations for three absorption peaks (2.74, 4.46 and 6.2 eV), we give a new assignment for the most disputed 3.62 eV one as well as for the two PA peaks.

  19. Chemical and Biological Significance of Oenothein B and Related Ellagitannin Oligomers with Macrocyclic Structure

    Directory of Open Access Journals (Sweden)

    Takashi Yoshida

    2018-03-01

    Full Text Available In 1990, Okuda et al. reported the first isolation and characterization of oenothein B, a unique ellagitannin dimer with a macrocyclic structure, from the Oenothera erythrosepala leaves. Since then, a variety of macrocyclic analogs, including trimeric–heptameric oligomers have been isolated from various medicinal plants belonging to Onagraceae, Lythraceae, and Myrtaceae. Among notable in vitro and in vivo biological activities reported for oenothein B are antioxidant, anti-inflammatory, enzyme inhibitory, antitumor, antimicrobial, and immunomodulatory activities. Oenothein B and related oligomers, and/or plant extracts containing them have thus attracted increasing interest as promising targets for the development of chemopreventive agents of life-related diseases associated with oxygen stress in human health. In order to better understand the significance of this type of ellagitannin in medicinal plants, this review summarizes (1 the structural characteristics of oenothein B and related dimers; (2 the oxidative metabolites of oenothein B up to heptameric oligomers; (3 the distribution of oenotheins and other macrocyclic analogs in the plant kingdom; and (4 the pharmacological activities hitherto documented for oenothein B, including those recently found by our laboratory.

  20. NMR studies of DNA oligomers and their interactions with minor groove binding ligands

    Energy Technology Data Exchange (ETDEWEB)

    Fagan, Patricia A. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

    1996-05-01

    The cationic peptide ligands distamycin and netropsin bind noncovalently to the minor groove of DNA. The binding site, orientation, stoichiometry, and qualitative affinity of distamycin binding to several short DNA oligomers were investigated by NMR spectroscopy. The oligomers studied contain A,T-rich or I,C-rich binding sites, where I = 2-desaminodeoxyguanosine. I•C base pairs are functional analogs of A•T base pairs in the minor groove. The different behaviors exhibited by distamycin and netropsin binding to various DNA sequences suggested that these ligands are sensitive probes of DNA structure. For sites of five or more base pairs, distamycin can form 1:1 or 2:1 ligand:DNA complexes. Cooperativity in distamycin binding is low in sites such as AAAAA which has narrow minor grooves, and is higher in sites with wider minor grooves such as ATATAT. The distamycin binding and base pair opening lifetimes of I,C-containing DNA oligomers suggest that the I,C minor groove is structurally different from the A,T minor groove. Molecules which direct chemistry to a specific DNA sequence could be used as antiviral compounds, diagnostic probes, or molecular biology tools. The author studied two ligands in which reactive groups were tethered to a distamycin to increase the sequence specificity of the reactive agent.

  1. Viscosity of nanoconfined polyamide-6,6 oligomers: atomistic reverse nonequilibrium molecular dynamics simulation.

    Science.gov (United States)

    Eslami, Hossein; Müller-Plathe, Florian

    2010-01-14

    Our new simulation scheme in isosurface-isothermal-isobaric ensemble [Eslami, H.; Mozaffari, F.; Moghadasi, J.; Müller-Plathe, F. J. Chem. Phys. 2008, 129, 194702], developed to simulate confined fluids in equilibrium with bulk, is applied to simulate polyamide-6,6 oligomers confined between graphite surfaces. The reverse nonequilibrium molecular dynamics simulation technique is employed to shear the graphite surfaces. In this work, six confined systems, with different surface separations, as well as the bulk fluid are simulated. Our results show a viscosity increase with respect to the bulk fluid, with decreasing distance between surfaces. Also, the calculated viscosities of the confined systems show an oscillatory behavior with maxima corresponding to well-formed layers between the surfaces. We observe a substantial slip at the surfaces, with the slip length depending on the shear rate and on the slit width. The slip length and the slip velocity show oscillatory behavior with out-of-phase oscillations with respect to the solvation force oscillations. Moreover, the temperature difference between coldest and hottest parts of the simulation box depends on the shear rate and on the layering effect (solvation force oscillations). An analysis of oligomer deformation under flow shows preferential alignment of oligomers parallel to the surfaces with increasing shear rate.

  2. Detection of the electronic structure of iron-(iii)-oxo oligomers forming in aqueous solutions.

    Science.gov (United States)

    Seidel, Robert; Kraffert, Katrin; Kabelitz, Anke; Pohl, Marvin N; Kraehnert, Ralph; Emmerling, Franziska; Winter, Bernd

    2017-12-13

    The nature of the small iron-oxo oligomers in iron-(iii) aqueous solutions has a determining effect on the chemical processes that govern the formation of nanoparticles in aqueous phase. Here we report on a liquid-jet photoelectron-spectroscopy experiment for the investigation of the electronic structure of the occurring iron-oxo oligomers in FeCl 3 aqueous solutions. The only iron species in the as-prepared 0.75 M solution are Fe 3+ monomers. Addition of NaOH initiates Fe 3+ hydrolysis which is followed by the formation of iron-oxo oligomers. At small enough NaOH concentrations, corresponding to approximately [OH]/[Fe] = 0.2-0.25 ratio, the iron oligomers can be stabilized for several hours without engaging in further aggregation. Here, we apply a combination of non-resonant as well as iron 2p and oxygen 1s resonant photoelectron spectroscopy from a liquid microjet to detect the electronic structure of the occurring species. Specifically, the oxygen 1s partial electron yield X-ray absorption (PEY-XA) spectra are found to exhibit a peak well below the onset of liquid water and OH - (aq) absorption. The iron 2p absorption gives rise to signal centered between the main absorption bands typical for aqueous Fe 3+ . Absorption bands in both PEY-XA spectra are found to correlate with an enhanced photoelectron peak near 20 eV binding energy, which demonstrates the sensitivity of resonant photoelectron (RPE) spectroscopy to mixing between iron and ligand orbitals. These various signals from the iron-oxo oligomers exhibit maximum intensity at [OH]/[Fe] = 0.25 ratio. For the same ratio, we observe changes in the pH as well as in complementary Raman spectra, which can be assigned to the transition from monomeric to oligomeric species. At approximately [OH]/[Fe] = 0.3 we begin to observe particles larger than 1 nm in radius, detected by small-angle X-ray scattering.

  3. Identification of Phenolic Acids and Changes in their Content during Fermentation and Ageing of White Wines Pošip and Rukatac

    Directory of Open Access Journals (Sweden)

    Tomislav Lovrić

    2002-01-01

    Full Text Available Identification of phenolic acids was performed and changes in their content during the production of autochthonous Croatian white wines Pošip and Rukatac (Vitis vinifera, L. were registered. In both varieties (Pošip, Rukatac the following phenolic acids were identified: gallic, protocatechuic and vanillic acids as hydroxybenzoic acids; and caffeic, p-coumaric and ferulic acids as hydroxycinnamic acids. It was found that there is a difference between hydroxybenzoic acid group and hydroxycinnamic acid group content and between their influences on the wine colour (colour intensity and hue.

  4. Investigation of the structure of isobutylene oligomers, used in the capacity of stock for succinimide additives, by the method of proton magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Iarmoliuk, V.M.; Garun, Ia.E.; Ostroverkhov, V.G.; Pustovit, V.E.; Tikhonov, V.P.

    1980-01-01

    By the method of proton magnetic resonance, investigation was made of the structure of hydrocarbon framework of isobutylene oligomers of the Salavatsk petrochemical plant, produced by the cation polymerization of the isobutane isobutylene fraction at a temperature from -10 to +20/sup 0/ with A1C1/sub 3/ and used in the production of succinide additives. Determination was made of the qualitative and quantitative compositions of the various structures in the oligomers. It is shown, that as a rule, oligobutenes are not pure oligomers of isobutylene, but represent, at least, fragments of four structures, which can be formed on the basis of isobutylene. The content of the given structures does not affect the reaction capacity of the oligomers in respect to the maleic anhydride. It was established, that the low molecular fraction, contained in oligomers up to 5%, are not isobutylene oligomers, but represent a low molecular polymer of butene-2 and its copolymer with isobutylene.

  5. Nanomolar Cellular Antisense Activity of Peptide Nucleic Acid (PNA) Cholic Acid ("Umbrella") and Cholesterol Conjugates Delivered by Cationic Lipids

    DEFF Research Database (Denmark)

    Shiraishi, Takehiko; Nielsen, Peter E

    2012-01-01

    of cholesterol and cholic acid ("umbrella") derivatives of splice correction antisense PNA oligomers. While the conjugates alone were practically inactive up to 1 µM, their activity was dramatically improved when delivered by a cationic lipid transfection agent (LipofectAMINE2000). In particular, PNAs...

  6. Sustainable hydrogen from bio-oil - Catalytic steam reforming of acetic acid as a model oxygenate

    NARCIS (Netherlands)

    Takanabe, Kazuhiro; Seshan, K.; Lefferts, Leon; Aika, Ken-ichi

    2004-01-01

    Steam reforming of acetic acid as a model oxygenate present in bio-oil over Pt/ZrO2 catalysts has been studied. Pt/ZrO2 catalysts are very active, completely converting acetic acid and give hydrogen yield close to thermodynamic equilibrium. The catalyst deactivated by formation of oligomers, which

  7. Template-directed synthesis of oligoguanylic acids - Metal ion catalysis

    Science.gov (United States)

    Bridson, P. K.; Fakhrai, H.; Lohrmann, R.; Orgel, L. E.; Van Roode, M.

    1981-01-01

    The effects of Zn(2+), Pb(2+) and other metal ions on the efficiency and stereo-selectivity of the template-directed oligomerization of guanosine 5'-phosphorimidazolide are investigated. Reactions were run in the presence of a polyC template in a 2,6-lutidine buffer, and products analyzed by high-performance liquid chromatography on an RPC-5 column. The presence of the Pb(2+) ion is found to lead to the formation of 2'-5' linked oligomers up to the 40-mer, while Zn(2+) favors the formation of predominantly 3'-5' linked oligomers up to the 35-mer. When amounts of uracil, cytidine or adenosine 5'-phosphorimidazole equal to those of the guanosine derivative are included in the reaction mixture, the incorrect base is incorporated into the oligomer about 10% of the time with a Pb(2+) catalyst, but less than 0.5% of the time with Zn(2+). The Sn(2+), Sb(3+) and Bi(3+) ions are also found to promote the formation of 2'-5' oligomers, although not as effectively as Pb(2+), while no metal ions other than Zn(2+) promote the formation of the 3'-5' oligomers. The results may be important for the understanding of the evolution of nucleic acid replication in the absence of enzymes.

  8. Selective amyloid β oligomer assay based on abasic site-containing molecular beacon and enzyme-free amplification.

    Science.gov (United States)

    Zhu, Linling; Zhang, Junying; Wang, Fengyang; Wang, Ya; Lu, Linlin; Feng, Chongchong; Xu, Zhiai; Zhang, Wen

    2016-04-15

    Amyloid-beta (Aβ) oligomers are highly toxic species in the process of Aβ aggregation and are regarded as potent therapeutic targets and diagnostic markers for Alzheimer's disease (AD). Herein, a label-free molecular beacon (MB) system integrated with enzyme-free amplification strategy was developed for simple and highly selective assay of Aβ oligomers. The MB system was constructed with abasic site (AP site)-containing stem-loop DNA and a fluorescent ligand 2-amino-5,6,7-trimethyl-1,8-naphyridine (ATMND), of which the fluorescence was quenched upon binding to the AP site in DNA stem. Enzyme-free amplification was realized by target-triggered continuous opening of two delicately designed MBs (MB1 and MB2). Target DNA hybridization with MB1 and then MB2 resulted in the release of two ATMND molecules in one binding event. Subsequent target recycling could greatly amplify the detection sensitivity due to the greatly enhanced turn-on emission of ATMND fluorescence. Combining with Aβ oligomers aptamers, the strategy was applied to analyze Aβ oligomers and the results showed that it could quantify Aβ oligomers with high selectivity and monitor the Aβ aggregation process. This novel method may be conducive to improve the diagnosis and pathogenic study of Alzheimer's disease. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. ENVIRONMENTAL ENRICHMENT STRENGTHENS CORTICOCORTICAL INTERACTIONS AND REDUCES AMYLOID-β OLIGOMERS IN AGED MICE

    Directory of Open Access Journals (Sweden)

    Marco eMainardi

    2014-01-01

    Full Text Available Brain aging is characterized by global changes which are thought to underlie age-related cognitive decline. These include variations in brain activity and the progressive increase in the concentration of soluble amyloid-β (Aβ oligomers, directly impairing synaptic function and plasticity even in the absence of any neurodegenerative disorder. Considering the high social impact of the decline in brain performance associated to aging, there is an urgent need to better understand how it can be prevented or contrasted. Lifestyle components, such as social interaction, motor exercise and cognitive activity, are thought to modulate brain physiology and its susceptibility to age-related pathologies. However, the precise functional and molecular factors that respond to environmental stimuli and might mediate their protective action again pathological aging still need to be clearly identified. To address this issue, we exploited environmental enrichment (EE, a reliable model for studying the effect of experience on the brain based on the enhancement of cognitive, social and motor experience, in aged wild-type mice. We analyzed the functional consequences of EE on aged brain physiology by performing in vivo local field potential (LFP recordings with chronic implants. In addition, we also investigated changes induced by EE on molecular markers of neural plasticity and on the levels of soluble Aβ oligomers. We report that EE induced profound changes in the activity of the primary visual and auditory cortices and in their functional interaction. At the molecular level, EE enhanced plasticity by an upward shift of the cortical excitation/inhibition balance. In addition, EE reduced brain Aβ oligomers and increased synthesis of the Aβ-degrading enzyme neprilysin. Our findings strengthen the potential of EE procedures as a non-invasive paradigm for counteracting brain aging processes.

  10. Multifunctional Cinnamic Acid Derivatives

    Directory of Open Access Journals (Sweden)

    Aikaterini Peperidou

    2017-07-01

    Full Text Available Our research to discover potential new multitarget agents led to the synthesis of 10 novel derivatives of cinnamic acids and propranolol, atenolol, 1-adamantanol, naphth-1-ol, and (benzylamino ethan-1-ol. The synthesized molecules were evaluated as trypsin, lipoxygenase and lipid peroxidation inhibitors and for their cytotoxicity. Compound 2b derived from phenoxyphenyl cinnamic acid and propranolol showed the highest lipoxygenase (LOX inhibition (IC50 = 6 μΜ and antiproteolytic activity (IC50 = 0.425 μΜ. The conjugate 1a of simple cinnamic acid with propranolol showed the higher antiproteolytic activity (IC50 = 0.315 μΜ and good LOX inhibitory activity (IC50 = 66 μΜ. Compounds 3a and 3b, derived from methoxylated caffeic acid present a promising combination of in vitro inhibitory and antioxidative activities. The S isomer of 2b also presented an interesting multitarget biological profile in vitro. Molecular docking studies point to the fact that the theoretical results for LOX-inhibitor binding are identical to those from preliminary in vitro study.

  11. Synthetic oligomer analysis using atmospheric pressure photoionization mass spectrometry at different photon energies

    International Nuclear Information System (INIS)

    Desmazières, Bernard; Legros, Véronique; Giuliani, Alexandre; Buchmann, William

    2014-01-01

    Graphical abstract: Atmospheric pressure photoIonization mass spectra of synthetic oligomers were recorded in the negative mode by varying the photon energy using synchrotron radiation. Photon energy required for an efficient ionization of the polymer was correlated to ionization potential of the solvent (for example 9.4 eV for tetrahydrofuran). -- Highlights: •Atmospheric pressure photoionization was performed using synchrotron radiation. •Photoionization of oligomers in THF with 10% CH 2 Cl 2 produces intact [M + Cl] − ions. •The photon energy required corresponds to ionization potential of the solvent. •Polymer distributions depend on source parameters such T °C and applied voltages. •Liquid chromatography was coupled to MS using an APPI interface for polymer analysis. -- Abstract: Atmospheric pressure photoionization (APPI) followed by mass spectrometric detection was used to ionize a variety of polymers: polyethylene glycol, polymethyl methacrylate, polystyrene, and polysiloxane. In most cases, whatever the polymer or the solvent used (dichloromethane, tetrahydrofuran, hexane, acetone or toluene), only negative ion mode produced intact ions such as chlorinated adducts, with no or few fragmentations, in contrast to the positive ion mode that frequently led to important in-source fragmentations. In addition, it was shown that optimal detection of polymer distributions require a fine tuning of other source parameters such as temperature and ion transfer voltage. Series of mass spectra were recorded in the negative mode, in various solvents (dichloromethane, tetrahydrofuran, hexane, toluene, and acetone), by varying the photon energy from 8 eV up to 10.6 eV using synchrotron radiation. To these solvents, addition of a classical APPI dopant (toluene or acetone) was not necessary. Courtesy of the synchrotron radiation, it was demonstrated that the photon energy required for an efficient ionization of the polymer was correlated to the ionization energy

  12. The role of stable α-synuclein oligomers in the molecular events underlying amyloid formation

    DEFF Research Database (Denmark)

    Lorenzen, Nikolai; Nielsen, Søren Bang; Buell, Alexander K.

    2014-01-01

    α-synuclein (αSN), whose aggregation is strongly implicated in the development of Parkinson’s disease (PD). The two types of oligomers are both formed under conditions where amyloid fibril formation is observed but differ in molecular weight by an order of magnitude. Both possess a degree of β......, either as precursors of fibrils or as species involved in the fibril elongation process or instead if they are associated with an aggregation process that is distinct from that generating mature fibrils. Here we describe and characterize in detail two well-defined oligomeric species formed by the protein...

  13. Synthetic oligomer analysis using atmospheric pressure photoionization mass spectrometry at different photon energies

    Energy Technology Data Exchange (ETDEWEB)

    Desmazières, Bernard [Global Bioenergies, 5 rue Henri Desbruyeres, 91030 Evry (France); Legros, Véronique [CNRS, UMR8587, Université d’Evry-Val-d’Essonne, Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement, F-91025 Evry (France); Giuliani, Alexandre [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette (France); UAR1008, CEPIA, INRA, Rue de la Geraudiere, F-44316 Nantes (France); Buchmann, William, E-mail: william.buchmann@univ-evry.fr [CNRS, UMR8587, Université d’Evry-Val-d’Essonne, Laboratoire Analyse et Modélisation pour la Biologie et l’Environnement, F-91025 Evry (France)

    2014-01-15

    Graphical abstract: Atmospheric pressure photoIonization mass spectra of synthetic oligomers were recorded in the negative mode by varying the photon energy using synchrotron radiation. Photon energy required for an efficient ionization of the polymer was correlated to ionization potential of the solvent (for example 9.4 eV for tetrahydrofuran). -- Highlights: •Atmospheric pressure photoionization was performed using synchrotron radiation. •Photoionization of oligomers in THF with 10% CH{sub 2}Cl{sub 2} produces intact [M + Cl]{sup −} ions. •The photon energy required corresponds to ionization potential of the solvent. •Polymer distributions depend on source parameters such T °C and applied voltages. •Liquid chromatography was coupled to MS using an APPI interface for polymer analysis. -- Abstract: Atmospheric pressure photoionization (APPI) followed by mass spectrometric detection was used to ionize a variety of polymers: polyethylene glycol, polymethyl methacrylate, polystyrene, and polysiloxane. In most cases, whatever the polymer or the solvent used (dichloromethane, tetrahydrofuran, hexane, acetone or toluene), only negative ion mode produced intact ions such as chlorinated adducts, with no or few fragmentations, in contrast to the positive ion mode that frequently led to important in-source fragmentations. In addition, it was shown that optimal detection of polymer distributions require a fine tuning of other source parameters such as temperature and ion transfer voltage. Series of mass spectra were recorded in the negative mode, in various solvents (dichloromethane, tetrahydrofuran, hexane, toluene, and acetone), by varying the photon energy from 8 eV up to 10.6 eV using synchrotron radiation. To these solvents, addition of a classical APPI dopant (toluene or acetone) was not necessary. Courtesy of the synchrotron radiation, it was demonstrated that the photon energy required for an efficient ionization of the polymer was correlated to the

  14. Radiation inactivation method provides evidence that membrane-bound mitochondrial creatine kinase is an oligomer

    International Nuclear Information System (INIS)

    Quemeneur, E.; Eichenberger, D.; Goldschmidt, D.; Vial, C.; Beauregard, G.; Potier, M.

    1988-01-01

    Lyophilized suspensions of rabbit heart mitochondria have been irradiated with varying doses of gamma rays. Mitochondrial creatine kinase activity was inactivated exponentially with a radiation inactivation size of 352 or 377 kDa depending upon the initial medium. These values are in good agreement with the molecular mass previously deduced from by permeation experiments: 357 kDa. This is the first direct evidence showing that the native form of mitochondrial creatine kinase is associated to the inner membrane as an oligomer, very likely an octamer

  15. Oligomer formation and G-quadruplex binding by purified murine Rif1 protein, a key organizer of higher-order chromatin architecture.

    Science.gov (United States)

    Moriyama, Kenji; Yoshizawa-Sugata, Naoko; Masai, Hisao

    2018-03-09

    Rap1-interacting protein 1 (Rif1) regulates telomere length in budding yeast. We previously reported that, in metazoans and fission yeast, Rif1 also plays pivotal roles in controlling genome-wide DNA replication timing. We proposed that Rif1 may assemble chromatin compartments that contain specific replication-timing domains by promoting chromatin loop formation. Rif1 also is involved in DNA lesion repair, restart after replication fork collapse, anti-apoptosis activities, replicative senescence, and transcriptional regulation. Although multiple physiological functions of Rif1 have been characterized, biochemical and structural information on mammalian Rif1 is limited, mainly because of difficulties in purifying the full-length protein. Here, we expressed and purified the 2418-amino-acid-long, full-length murine Rif1 as well as its partially truncated variants in human 293T cells. Hydrodynamic analyses indicated that Rif1 forms elongated or extended homo-oligomers in solution, consistent with the presence of a HEAT-type helical repeat segment known to adopt an elongated shape. We also observed that the purified murine Rif1 bound G-quadruplex (G4) DNA with high specificity and affinity, as was previously shown for Rif1 from fission yeast. Both the N-terminal (HEAT-repeat) and C-terminal segments were involved in oligomer formation and specifically bound G4 DNA, and the central intrinsically disordered polypeptide segment increased the affinity for G4. Of note, pulldown assays revealed that Rif1 simultaneously binds multiple G4 molecules. Our findings support a model in which Rif1 modulates chromatin loop structures through binding to multiple G4 assemblies and by holding chromatin fibers together. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Formation of high-order oligomers is required for functional bioactivity of an African bat henipavirus surface glycoprotein.

    Science.gov (United States)

    Behner, Laura; Zimmermann, Louisa; Ringel, Marc; Weis, Michael; Maisner, Andrea

    2018-05-01

    Hendra virus (HeV) and Nipah virus (NiV) are highly pathogenic henipaviruses originating from fruit bats in Australia and Asia that can cause severe infections in livestock and humans. In recent years, also African bat henipaviruses were identified at the nucleic acid level. To assess their potential to replicate in non-bat species, several studies were performed to characterize the two surface glycoproteins required for virus entry and spread by cell-cell fusion. It has been shown that surface expression and fusion-helper function of the receptor-binding G protein of Kumasi virus (KV), the prototypic Ghanaian bat henipavirus, is reduced compared to other non-African henipavirus G proteins. Immunostainings and pulse-chase analysis revealed a delayed export of KV G from the ER. As defects in oligomerization of viral glycoproteins can be responsible for limited surface transport thereby restricting the bioactivity, we analyzed the oligomerization pattern of KV G. In contrast to HeV and NiV whose G proteins are known to be expressed at a dimer-tetramer ratio of 1:1, KV G almost exclusively formed stable tetramers or higher oligomers. KV G also showed less stringent requirements for defined stalk cysteines to form dimers and tetramers. Interestingly, any changes in the oligomeric forms negatively affected the fusion-helper activity although surface expression and receptor binding was unchanged. This clearly indicates that the formation of mostly higher oligomeric KV G forms is not a deficiency responsible for ER retention, but is rather a basic structural feature essential for the bioactivity of this African bat henipavirus glycoprotein. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Gibbs energies of protonation and complexation of platinum and vanadate metal ions with naringenin and phenolic acids: Theoretical calculations associated with experimental values

    International Nuclear Information System (INIS)

    Fazary, Ahmed E.; Alshihri, Ayed S.; Alfaifi, Mohammad Y.; Saleh, Kamel A.; Elbehairi, Serag Eldin I.; Fawy, Khaled F.; Abd-Rabboh, Hisham S.M.

    2016-01-01

    Highlights: • The experimental thermodynamic equilibrium and stability constants of vanadium and platinum complexes involving naringin, ferulic acid, p-coumaric acid, caffeic acid, vanillic acid, sinapic acid, and gallic acid were determined. • The theoretical calculations of the free energy changes associated with the ligand protonation, and metal ion–ligand complex formation equilibria using density function theory calculations, providing a complete picture of the microscopic equilibria of the studied complex systems. - Abstract: The Experimental thermodynamic equilibrium (pK_a values) and stability (log β) constants of vanadium and platinum binary and mixed ligand complexes involving naringenin, ferulic acid, p-coumaric acid, caffeic acid, vanillic acid, sinapic acid, and gallic acid were determined at 310.15 K in 0.16 mol·dm"−"3 KCl aqueous solutions using pH-potentiometric technique and by means of two estimation models (HYPERQUAD 2008 and Bjerrum–Calvin). The theoretical calculations of overall protonation and stability constants of the metal complex species in solution were predicted as the free energy change associated with the ligand protonation, and metal ion–ligand complex formation equilibria (species solvation/de-solvation) using ab initio and density function theory (DFT) calculations. The usage of the experimental potentiometry technique and theoretical predictions provides a complete picture of the microscopic equilibria of the studied systems (vanadium/platinum–naringenin–phenolic acid). Specifically, this theoretically DFT predications would be useful to determine the most real protonation constants of the studied bioligands in which the binding sites changes due to the ligand protonation/deprotonation equilibria. Also, the complexing capacities of vanadium and platinum towards naringenin, ferulic acid, p-coumaric acid, caffeic acid, vanillic acid, sinapic acid, and gallic acid in solutions were evaluated and discussed. From the

  18. Characterizing the Dynamics of α-Synuclein Oligomers Using Hydrogen/Deuterium Exchange Monitored by Mass Spectrometry

    DEFF Research Database (Denmark)

    Mysling, Simon; Betzer, Cristine; Jensen, Poul Henning

    2013-01-01

    Soluble oligomers formed by α-synuclein (αSN) are suspected to play a central role in neuronal cell death during Parkinson's disease. While studies have probed the surface structure of these oligomers, little is known about the backbone dynamics of αSN when they form soluble oligomers. Using...... analyses performed on αSN fibrils and indicated a possible zipperlike maturation mechanism for αSN aggregates. We find the protected N-terminus (residues 4-17) to be of particular interest, as this region has previously been observed to be highly dynamic for both monomeric and fibrillar αSN. This region...... has mainly been described in relation to membrane binding of αSN, and structuring may be important in relation to disease....

  19. Combining Orthogonal Chain-End Deprotections and Thiol-Maleimide Michael Coupling: Engineering Discrete Oligomers by an Iterative Growth Strategy.

    Science.gov (United States)

    Huang, Zhihao; Zhao, Junfei; Wang, Zimu; Meng, Fanying; Ding, Kunshan; Pan, Xiangqiang; Zhou, Nianchen; Li, Xiaopeng; Zhang, Zhengbiao; Zhu, Xiulin

    2017-10-23

    Orthogonal maleimide and thiol deprotections were combined with thiol-maleimide coupling to synthesize discrete oligomers/macromolecules on a gram scale with molecular weights up to 27.4 kDa (128mer, 7.9 g) using an iterative exponential growth strategy with a degree of polymerization (DP) of 2 n -1. Using the same chemistry, a "readable" sequence-defined oligomer and a discrete cyclic topology were also created. Furthermore, uniform dendrons were fabricated using sequential growth (DP=2 n -1) or double exponential dendrimer growth approaches (DP=22n -1) with significantly accelerated growth rates. A versatile, efficient, and metal-free method for construction of discrete oligomers with tailored structures and a high growth rate would greatly facilitate research into the structure-property relationships of sophisticated polymeric materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Modulation of α-synuclein fibrillization by ring-fused 2-pyridones: templation and inhibition involve oligomers with different structure.

    Science.gov (United States)

    Horvath, Istvan; Sellstedt, Magnus; Weise, Christoph; Nordvall, Lina-Maria; Krishna Prasad, G; Olofsson, Anders; Larsson, Göran; Almqvist, Fredrik; Wittung-Stafshede, Pernilla

    2013-04-15

    In a recent study we discovered that a ring-fused 2-pyridone compound triggered fibrillization of a key protein in Parkinson's disease, α-synuclein. To reveal how variations in compound structure affect protein aggregation, we now prepared a number of strategic analogs and tested their effects on α-synuclein amyloid fiber formation in vitro. We find that, in contrast to the earlier templating effect, some analogs inhibit α-synuclein fibrillization. For both templating and inhibiting compounds, the key species formed in the reactions are α-synuclein oligomers that contain compound. Despite similar macroscopic appearance, the templating and inhibiting oligomers are distinctly different in secondary structure content. When the inhibitory oligomers are added in seed amounts, they inhibit fresh α-synuclein aggregation reactions. Our study demonstrates that small chemical changes to the same central fragment can result in opposite effects on protein aggregation. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Effect of Conjugation Length on Photoinduced Charge-Transfer in π-Conjugated Oligomer-Acceptor Dyads

    KAUST Repository

    Jiang, Junlin

    2017-05-25

    A series of -conjugated oligomer-acceptor dyads were synthesized that feature oligo(phenylene ethynylene) (OPE) conjugated backbones end-capped with a naphthalene diimide (NDI) acceptor. The OPE segments vary in length from 4 to 8 phenylene ethynene units (PEn-NDI, where n = 4, 6 and 8). Fluorescence and transient absorption spectroscopy reveals that intramolecular OPE NDI charge transfer dominates the deactivation of excited states of the PEn-NDI oligomers. Both charge separation (CS) and charge recombination (CR) are strongly exothermic (G0CS ~ -1.1 and G0CR ~ -2.0 eV), and the driving forces do not vary much across the series because the oxidation and reduction potentials and singlet energies of the OPEs do not vary much with their length. Bimolecular photoinduced charge transfer between model OPEs that do not contain the NDI acceptors with methyl viologen was studied, and the results reveal that the absorption of the cation radical state (OPE+•) remains approximately constant ( ~ 575 nm) regardless of oligomer length. This finding suggests that the cation radical (polaron) of the OPE is relatively localized, effectively occupying a confined segment of n 4 repeat units in the longer oligomers. Photoinduced intramolecular electron transfer dynamics in the PEn-NDI series was investigated by UV-visible femtosecond transient absorption spectroscopy with visible and mid-infrared probes. Charge separation occurs on the 1 – 10 ps timescale, with the rates decreasing slightly with increased oligomer length (βCS ~ 0.15 Å-1). The rate for charge-recombination decreases in the sequence PE4-NDI > PE6-NDI ~ PE8-NDI. The discontinuous distance dependence in the rate for charge recombination may be related to the spatial localization of the positive polaron state in the longer oligomers.

  2. Effect of Conjugation Length on Photoinduced Charge-Transfer in π-Conjugated Oligomer-Acceptor Dyads

    KAUST Repository

    Jiang, Junlin; Alsam, Amani Abdu; Wang, Shanshan; Aly, Shawkat Mohammede; Pan, Zhenxing; Mohammed, Omar F.; Schanze, Kirk S.

    2017-01-01

    A series of -conjugated oligomer-acceptor dyads were synthesized that feature oligo(phenylene ethynylene) (OPE) conjugated backbones end-capped with a naphthalene diimide (NDI) acceptor. The OPE segments vary in length from 4 to 8 phenylene ethynene units (PEn-NDI, where n = 4, 6 and 8). Fluorescence and transient absorption spectroscopy reveals that intramolecular OPE NDI charge transfer dominates the deactivation of excited states of the PEn-NDI oligomers. Both charge separation (CS) and charge recombination (CR) are strongly exothermic (G0CS ~ -1.1 and G0CR ~ -2.0 eV), and the driving forces do not vary much across the series because the oxidation and reduction potentials and singlet energies of the OPEs do not vary much with their length. Bimolecular photoinduced charge transfer between model OPEs that do not contain the NDI acceptors with methyl viologen was studied, and the results reveal that the absorption of the cation radical state (OPE+•) remains approximately constant ( ~ 575 nm) regardless of oligomer length. This finding suggests that the cation radical (polaron) of the OPE is relatively localized, effectively occupying a confined segment of n 4 repeat units in the longer oligomers. Photoinduced intramolecular electron transfer dynamics in the PEn-NDI series was investigated by UV-visible femtosecond transient absorption spectroscopy with visible and mid-infrared probes. Charge separation occurs on the 1 – 10 ps timescale, with the rates decreasing slightly with increased oligomer length (βCS ~ 0.15 Å-1). The rate for charge-recombination decreases in the sequence PE4-NDI > PE6-NDI ~ PE8-NDI. The discontinuous distance dependence in the rate for charge recombination may be related to the spatial localization of the positive polaron state in the longer oligomers.

  3. Length dependence of rectification in organic co-oligomer spin rectifiers

    International Nuclear Information System (INIS)

    Hu Gui-Chao; Zhang Zhao; Li Ying; Ren Jun-Feng; Wang Chuan-Kui

    2016-01-01

    The rectification ratio of organic magnetic co-oligomer diodes is investigated theoretically by changing the molecular length. The results reveal two distinct length dependences of the rectification ratio: for a short molecular diode, the charge-current rectification changes little with the increase of molecular length, while the spin-current rectification is weakened sharply by the length; for a long molecular diode, both the charge-current and spin-current rectification ratios increase quickly with the length. The two kinds of dependence switch at a specific length accompanied with an inversion of the rectifying direction. The molecular ortibals and spin-resolved transmission analysis indicate that the dominant mechanism of rectification suffers a change at this specific length, that is, from asymmetric shift of molecular eigenlevels to asymmetric spatial localization of wave functions upon the reversal of bias. This work demonstrates a feasible way to control the rectification in organic co-oligomer spin diodes by adjusting the molecular length. (paper)

  4. Self-Healable and Reprocessable Polysulfide Sealants Prepared from Liquid Polysulfide Oligomer and Epoxy Resin.

    Science.gov (United States)

    Gao, Wentong; Bie, Mengyao; Liu, Fu; Chang, Pengshan; Quan, Yiwu

    2017-05-10

    Polysulfide sealants have been commercially applied in many industrial fields. In this article, we study the self-healing property of the epoxy resin-cured polysulfide sealants for the first time. The obtained sealants showed a flexible range of ultimate elongation of 157-478% and a tensile strength of 1.02-0.75 MPa corresponding to different polysulfide oligomers. By taking advantage of the dynamic reversible exchange of disulfide bonds, polysulfide sealants exhibited good self-healing ability under a moderate thermal stimulus. A higher molecular weight and a lower degree of cross-linking of polysulfide oligomer were helpful in improving the ultimate elongation and healing efficiency of the polysulfide sealants. After subjecting to a temperature of 75 °C for 60 min, both the tensile strength and ultimate elongation of a fully cut sample, LP55-F, were restored to 91% of the original values, without affecting the sealing property. Furthermore, the sample exhibited excellent reshaping and reprocessing abilities. These outcomes offer a paradigm toward sustainable industrial applications of the polysulfide-based sealants.

  5. Identification of chlorinated oligomers formed during anodic oxidation of phenol in the presence of chloride

    International Nuclear Information System (INIS)

    Chen, Linxi; Campo, Pablo; Kupferle, Margaret J.

    2015-01-01

    Graphical abstract: - Highlights: • By-products from anodic oxidation of phenol in the presence of chloride are investigated. • Chlorinated oligomer formation is demonstrated by LC-QTOF-MS. • They have structures similar to triclosan and polychlorinated dibenzo-p-dioxins. - Abstract: Chlorinated oligomer intermediates formed during the anodic electrochemical oxidation of phenol with a boron-doped diamond electrode were studied at two different concentrations of chloride (5 mM and 50 mM). Under the same ionic strength, with sodium sulfate being the make-up ion, a 10-fold increase in Cl − led to removal rates 10.8, 1.5, and 1.4 times higher for phenol, TOC, and COD, respectively. Mono-, di- and trichlorophenols resulting from electrophilic substitution were the identified by-products. Nevertheless, discrepancies between theoretical and measured TOC values along with gaps in the mass balance of chlorine-containing species indicated the formation of unaccounted-for chlorinated by-products. Accurate mass measurements by liquid chromatography quadrupole time-of-flight mass spectrometry and MS-MS fragmentation spectra showed that additional compounds formed were dimers and trimers of phenol with structures similar to triclosan and polychlorinated dibenzo-p-dioxins

  6. Morpholino oligomer-mediated exon skipping averts the onset of dystrophic pathology in the mdx mouse.

    Science.gov (United States)

    Fletcher, Sue; Honeyman, Kaite; Fall, Abbie M; Harding, Penny L; Johnsen, Russell D; Steinhaus, Joshua P; Moulton, Hong M; Iversen, Patrick L; Wilton, Stephen D

    2007-09-01

    Duchenne and Becker muscular dystrophies are allelic disorders arising from mutations in the dystrophin gene. Duchenne muscular dystrophy is characterized by an absence of functional protein, whereas Becker muscular dystrophy, commonly caused by in-frame deletions, shows synthesis of partially functional protein. Anti-sense oligonucleotides can induce specific exon removal during processing of the dystrophin primary transcript, while maintaining or restoring the reading frame, and thereby overcome protein-truncating mutations. The mdx mouse has a non-sense mutation in exon 23 of the dystrophin gene that precludes functional dystrophin production, and this model has been used in the development of treatment strategies for dystrophinopathies. A phosphorodiamidate morpholino oligomer (PMO) has previously been shown to exclude exon 23 from the dystrophin gene transcript and induce dystrophin expression in the mdxmouse, in vivo and in vitro. In this report, a cell-penetrating peptide (CPP)-conjugated oligomer targeted to the mouse dystrophin exon 23 donor splice site was administered to mdxmice by intraperitoneal injection. We demonstrate dystrophin expression and near-normal muscle architecture in all muscles examined, except for cardiac muscle. The CPP greatly enhanced uptake of the PMO, resulting in widespread dystrophin expression.

  7. Identification of chlorinated oligomers formed during anodic oxidation of phenol in the presence of chloride

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Linxi; Campo, Pablo; Kupferle, Margaret J., E-mail: margaret.kupferle@uc.edu

    2015-02-11

    Graphical abstract: - Highlights: • By-products from anodic oxidation of phenol in the presence of chloride are investigated. • Chlorinated oligomer formation is demonstrated by LC-QTOF-MS. • They have structures similar to triclosan and polychlorinated dibenzo-p-dioxins. - Abstract: Chlorinated oligomer intermediates formed during the anodic electrochemical oxidation of phenol with a boron-doped diamond electrode were studied at two different concentrations of chloride (5 mM and 50 mM). Under the same ionic strength, with sodium sulfate being the make-up ion, a 10-fold increase in Cl{sup −} led to removal rates 10.8, 1.5, and 1.4 times higher for phenol, TOC, and COD, respectively. Mono-, di- and trichlorophenols resulting from electrophilic substitution were the identified by-products. Nevertheless, discrepancies between theoretical and measured TOC values along with gaps in the mass balance of chlorine-containing species indicated the formation of unaccounted-for chlorinated by-products. Accurate mass measurements by liquid chromatography quadrupole time-of-flight mass spectrometry and MS-MS fragmentation spectra showed that additional compounds formed were dimers and trimers of phenol with structures similar to triclosan and polychlorinated dibenzo-p-dioxins.

  8. Atomistic simulation of CO 2 solubility in poly(ethylene oxide) oligomers

    KAUST Repository

    Hong, Bingbing

    2013-10-02

    We have performed atomistic molecular dynamics simulations coupled with thermodynamic integration to obtain the excess chemical potential and pressure-composition phase diagrams for CO2 in poly(ethylene oxide) oligomers. Poly(ethylene oxide) dimethyl ether, CH3O(CH 2CH2O)nCH3 (PEO for short) is a widely applied physical solvent that forms the major organic constituent of a class of novel nanoparticle-based absorbents. Good predictions were obtained for pressure-composition-density relations for CO2 + PEO oligomers (2 ≤ n ≤ 12), using the Potoff force field for PEO [J. Chem. Phys. 136, 044514 (2012)] together with the TraPPE model for CO2 [AIChE J. 47, 1676 (2001)]. Water effects on Henrys constant of CO2 in PEO have also been investigated. Addition of modest amounts of water in PEO produces a relatively small increase in Henrys constant. Dependence of the calculated Henrys constant on the weight percentage of water falls on a temperature-dependent master curve, irrespective of PEO chain length. © 2013 Taylor & Francis.

  9. Enhanced Solubilization of Fluoranthene by Hydroxypropyl β-Cyclodextrin Oligomer for Bioremediation

    Directory of Open Access Journals (Sweden)

    Kyeong Hui Park

    2018-01-01

    Full Text Available Fluoranthene (FT is a polycyclic aromatic hydrocarbon (PAH, consisting of naphthalene and benzene rings connected by a five-member ring. It is widespread in the environment. The hydrophobicity of FT limits its availability for biological uptake and degradation. In this study, hydroxypropyl β-cyclodextrin oligomers (HP-β-CD-ol were synthesized with epichlorohydrin (EP, while the solubility enhancement of FT by HP-β-CD-ol was investigated in water. The synthesized HP-β-CD-ol was characterized by MALDI-TOF mass spectrometry (MS, 1H NMR, and 13C NMR spectroscopy. The solubility of FT increased 178-fold due to the complex formation with HP-β-CD oligomers. The inclusion complexes of FT/HP-β-CD-ol were analyzed using Fourier-Transform Infrared (FT-IR, Differential Scanning Calorimetry (DSC, Scanning Electron Microscope (SEM, and Nuclear Overhauser Effect Spectroscopy Nuclear magnetic resonance (NOESY NMR spectroscopy. On the basis of these results, HP-β-CD-ol is recommended as a potential solubilizer for the development of PAH removal systems.

  10. Steady State and Time-Resolved Fluorescence Dynamics of Triphenylamine Based Oligomers with Phenylene/Thiophene/Furan in Solvents

    International Nuclear Information System (INIS)

    Qi, Zeng; Ying-Liang, Liu; Kang, Meng; Xiang-Jie, Zhao; Shu-Feng, Wang; Qi-Huang, Gong

    2009-01-01

    We investigate the photo-physical properties of a series of triphenylamine-based oligomers by steady-state and picosecond transient fluorescence measurements in solvents. The oligomers are composed alternatively with triphenylamine and phenylene/thiophene/furan group, bridged by vinyl group (PNB/PNT/PNF). Their fluorescence spectra show bathochromic phenomenon with solvent polarity and viscosity increasing. The fluorescence decays are bi-exponential for PNB and PNT, and tri-exponential for PNF in THF and aniline. The strong viscosity dependence suggests conformational relaxation along the PNF chain after photo excitation. (condensed matter: electronicstructure, electrical, magnetic, and opticalproperties)

  11. Theoretical study of stability geometrical and electronic structure of (BeHsub(2))sub(n) oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Sukhanov, L P; Boldyrev, A I; Charkin, O P [AN SSSR, Moscow. Inst. Novykh Khimicheskikh Problem

    1983-01-01

    The Hartree-Fock-Ruthane method with the Roos-Siegbahn two-exponent basis is used to calculate stability, geometrical and electronic structures of (BeHsub(2))sub(n) oligomers, where n=1, 2, 3, 4 and 6. It is shown that with the growth of oligomerization degree n stability of linear band structure is increased as compared with other configurations including high-coordination volumetric ones. Tendencies in formation with n growth of geometrical, energetic characteristics, electronic structure of (BeHsub(2))sub(n) oligomers of band type are analysed.

  12. Fluorine-18 labelling of a novel series of chimeric, mdm2 oncogene targeting, peptide-pna oligomers using [18F]FPyME

    International Nuclear Information System (INIS)

    Kuhnast, B.; Hinnen, F.; Boisgard, R.; Tavitian, B.; Dolle, F.; Nielsen, P.

    2011-01-01

    Complete text of publication follows: Peptide nucleic acids (PNAs) form a unique class of synthetic macromolecules, originally designed as ligands for the recognition of double stranded DNA, where the deoxyribose phosphate backbone of original DNA is replaced by a pseudo-peptide N-(2-aminoethyl)glycyl backbone, while retaining the nucleobases of DNA. PNAs have already showed promising therapeutic potential as antisense and anti-gene agents and are inspiring the development of a variety of research and diagnostic assays, including their use as imaging tools. Within our intensive programs of development of oligonucleotide-based probes for PET-imaging, a novel series of chimeric peptide-PNA oligomers has been designed as complementary antisense probes targeting a specific 15-base sequence located at the intron-exon junction of the pre-mRNA of the murine double minute (mdm2) oncogene. This gene codes for a p53 interacting protein that represses p53 transcriptional activity, and appears to be over expressed in several tumor types including soft tissue sarcomas and osteosarcomas as well as breast tumors. For in vivo 3D-imaging purposes, all oligomers include a cysteine thus providing a sulfhydryl function permitting prosthetic conjugation with maleimide-based reagents such as AlexaFluor680 R (AF680) for optical fluorescence imaging and [ 18 F]FPyME (1-[3-(2-[ 18 F]fluoropyridin-3-yloxy)propyl]pyrrole-2, 5-dione), a prosthetic reagent labeled with the positron-emitter fluorine-18 for PET imaging, which latter work is presented herein. Methods: [ 18 F]FPyME was prepared using a three-step radiochemical pathway already reported and includes an HPLC-purification (semi-preparative SiO 2 Zorbax R Rx-SIL, Hewlett Packard). [ 18 F]FPyME was conjugated with the peptide-PNA oligomers (PNA3132, PNA3133, and PNA3135, 0.25-0.30 micro-moles) in 1/9 (v:v) mixture (1 mL) of DMSO and 0.1 M aq. PBS (pH 8) at room temperature for 15 min. The [ 18 F]FPyME-conjugated products (c-[ 18 F

  13. Interaction of milk whey protein with common phenolic acids

    Science.gov (United States)

    Zhang, Hao; Yu, Dandan; Sun, Jing; Guo, Huiyuan; Ding, Qingbo; Liu, Ruihai; Ren, Fazheng

    2014-01-01

    Phenolics-rich foods such as fruit juices and coffee are often consumed with milk. In this study, the interactions of α-lactalbumin and β-lactoglobulin with the phenolic acids (chlorogenic acid, caffeic acid, ferulic acid, and coumalic acid) were examined. Fluorescence, CD, and FTIR spectroscopies were used to analyze the binding modes, binding constants, and the effects of complexation on the conformation of whey protein. The results showed that binding constants of each whey protein-phenolic acid interaction ranged from 4 × 105 to 7 × 106 M-n and the number of binding sites n ranged from 1.28 ± 0.13 to 1.54 ± 0.34. Because of these interactions, the conformation of whey protein was altered, with a significant reduction in the amount of α-helix and an increase in the amounts of β-sheet and turn structures.

  14. Identification/quantification of free and bound phenolic acids in peel and pulp of apples (Malus domestica) using high resolution mass spectrometry (HRMS).

    Science.gov (United States)

    Lee, Jihyun; Chan, Bronte Lee Shan; Mitchell, Alyson E

    2017-01-15

    Free and bound phenolic acids were measured in the pulp and peel of four varieties of apples using high resolution mass spectrometry. Twenty-five phenolic acids were identified and included: 8 hydroxybenzoic acids, 11 hydroxycinnamic acids, 5 hydroxyphenylacetic acids, and 1 hydoxyphenylpropanoic acid. Several phenolics are tentatively identified for the first time in apples and include: methyl gallate, ethyl gallate, hydroxy phenyl acetic acid, three phenylacetic acid isomers, 3-(4-hydroxyphenyl)propionic acid, and homoveratric acid. With exception of chlorogenic and caffeic acid, most phenolic acids were quantified for the first time in apples. Significant varietal differences (pacids were higher in the pulp as compared to apple peel (dry weight) in all varieties. Coumaroylquinic, protocatechuic, 4-hydroxybenzoic, vanillic and t-ferulic acids were present in free forms. With exception of chlorogenic acid, all other phenolic acids were present only as bound forms. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Formation of a stable oligomer of beta-2 microglobulin requires only transient encounter with Cu(II).

    Science.gov (United States)

    Calabrese, Matthew F; Miranker, Andrew D

    2007-03-16

    Beta-2 Microglobulin (beta2m) is a small, globular protein, with high solubility under conditions comparable to human serum. A complication of hemodialysis in renal failure patients is the deposition of unmodified beta2m as amyloid fibers. In vitro, exposure of beta2m to equimolar Cu(2+) under near-physiological conditions can result in self-association leading to amyloid fiber formation. Previously, we have shown that the early steps in this process involve a catalyzed structural rearrangement followed by formation of discrete oligomers. These oligomers, however, have a continued requirement for Cu(2+) while mature fibers are resistant to addition of metal chelate. Here, we report that the transition from Cu(2+) dependent to chelate resistant states occurs in the context of small oligomers, dimeric to hexameric in size. These species require Cu(2+) to form, but once generated, do not need metal cation for stability. Importantly, this transition occurs gradually over several days and the resulting oligomers are isolatable and kinetically stable on timescales exceeding weeks. In addition, formation is enhanced by levels of urea similar to those found in hemodialysis patients. Our results are consistent with our hypothesis that transient encounter of full-length wild-type beta2m with transition metal cation at the dialysis membrane interface is causal to dialysis related amyloidosis.

  16. Combined HILIC-ELSD/ESI-MSn enables the separation, identification and quantification of sugar beet pectin derived oligomers

    NARCIS (Netherlands)

    Remoroza, C.A.; Cord-Landwehr, S.; Leijdekkers, A.G.M.; Moerschbacher, B.M.; Schols, H.A.; Gruppen, H.

    2012-01-01

    The combined action of endo-polygalacturonase (endo-PGII), pectin lyase (PL), pectin methyl esterase (fungal PME) and RG-I degrading enzymes enabled the extended degradation of methylesterified and acetylated sugar beet pectins (SBPs). The released oligomers were separated, identified and quantified

  17. Parkinson's disease in the spotlight: unraveling nanoscale α-Synuclein oligomers using ultrasensitive single-molecule spectroscopy

    NARCIS (Netherlands)

    Zijlstra, Niels

    2014-01-01

    During the last 15 years, we have witnessed a major shift in the research focus to understand the cause of amyloid diseases. The attention has shifted from the fully matured amyloid fibrils to the nanometer sized aggregation intermediates called oligomers as the potentially cytotoxic species that

  18. Charge-carrier selective electrodes for organic bulk heterojunction solar cell by contact-printed siloxane oligomers

    International Nuclear Information System (INIS)

    Hwang, Hyun-Sik; Khang, Dahl-Young

    2015-01-01

    ‘Smart’ (or selective) electrode for charge carriers, both electrons and holes, in organic bulk-heterojunction (BHJ) solar cells using insertion layers made of hydrophobically-recovered and contact-printed siloxane oligomers between electrodes and active material has been demonstrated. The siloxane oligomer insertion layer has been formed at a given interface simply by conformally-contacting a cured slab of polydimethylsiloxane stamp for less than 100 s. All the devices, either siloxane oligomer printed at one interface only or printed at both interfaces, showed efficiency enhancement when compared to non-printed ones. The possible mechanism that is responsible for the observed efficiency enhancement has been discussed based on the point of optimum symmetry and photocurrent analysis. Besides its simplicity and large-area applicability, the demonstrated contact-printing technique does not involve any vacuum or wet processing steps and thus can be very useful for the roll-based, continuous production scheme for organic BHJ solar cells. - Highlights: • Carrier-selective insertion layer in organic bulk heterojunction solar cells • Simple contact-printing of siloxane oligomers improves cell efficiency. • Printed siloxane layer reduces carrier recombination at electrode surfaces. • Siloxane insertion layer works equally well at both electrode surfaces. • Patterned PDMS stamp shortens the printing time within 100 s

  19. Caspase-cleaved tau exhibits rapid memory impairment associated with tau oligomers in a transgenic mouse model.

    Science.gov (United States)

    Kim, YoungDoo; Choi, Hyunwoo; Lee, WonJae; Park, Hyejin; Kam, Tae-In; Hong, Se-Hoon; Nah, Jihoon; Jung, Sunmin; Shin, Bora; Lee, Huikyong; Choi, Tae-Yong; Choo, Hyosun; Kim, Kyung-Keun; Choi, Se-Young; Kayed, Rakez; Jung, Yong-Keun

    2016-03-01

    In neurodegenerative diseases like AD, tau forms neurofibrillary tangles, composed of tau protein. In the AD brain, activated caspases cleave tau at the 421th Asp, generating a caspase-cleaved form of tau, TauC3. Although TauC3 is known to assemble rapidly into filaments in vitro, a role of TauC3 in vivo remains unclear. Here, we generated a transgenic mouse expressing human TauC3 using a neuron-specific promoter. In this mouse, we found that human TauC3 was expressed in the hippocampus and cortex. Interestingly, TauC3 mice showed drastic learning and spatial memory deficits and reduced synaptic density at a young age (2-3months). Notably, tau oligomers as well as tau aggregates were found in TauC3 mice showing memory deficits. Further, i.p. or i.c.v. injection with methylene blue or Congo red, inhibitors of tau aggregation in vitro, and i.p. injection with rapamycin significantly reduced the amounts of tau oligomers in the hippocampus, rescued spine density, and attenuated memory impairment in TauC3 mice. Together, these results suggest that TauC3 facilitates early memory impairment in transgenic mice accompanied with tau oligomer formation, providing insight into the role of TauC3 in the AD pathogenesis associated with tau oligomers and a useful AD model to test drug candidates. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Unraveling the Role of Π - Conjugation in Thiophene Oligomers for Optoelectronic Properties by DFT/TDDFT Approach

    Directory of Open Access Journals (Sweden)

    Gajalakshmi

    Full Text Available ABSTRACT Thiophene oligomer has been investigated using DFT/TDDFT calculations with an aim to check its suitability for opto electronic applications and also to analyse the influence of π-bridge. Our results revealed that thiophene oligomers have excellent π-conjugation throughout. FMO analysis give an estimate of band gap of thiophene oligomer and further revealed HOMO are localized on π - bridge, donor group and LUMO are localized on π - bridge and acceptor group. A TDDFT calculation has been performed to understand the absorption properties of them in gas phase and solvent phase. PCM calculations convey that absorption maxima show positive solvatochromism. Among the designed candidates, the one with more π - bridge show higher wavelength of absorption maxima and would be a choice for better optoelectronic materials. NBO analysis provides support for complete delocalization in these systems. It is interesting to note that oligomer with more π-bridge display an enhanced optoelectronic properties than with less π - bridge.

  1. Unified approach to catechin hetero-oligomers: first total synthesis of trimer EZ-EG-CA isolated from Ziziphus jujuba.

    Science.gov (United States)

    Yano, Takahisa; Ohmori, Ken; Takahashi, Haruko; Kusumi, Takenori; Suzuki, Keisuke

    2012-10-14

    A catechin hetero-trimer isolated from Ziziphus jujuba has been synthesized. Among three constituent monomers, (-)-epiafzelechin and (-)-epigallocatechin were prepared by de novo synthesis. Trimer formation relied on the unified approach to oligomers based on the bromo-capping and the orthogonal activation, reaching the reported structure of the natural product.

  2. The phenolic acids of some species of the Oenothera L. genus

    Directory of Open Access Journals (Sweden)

    Tadeusz Krzaczek

    2014-01-01

    Full Text Available The occurence and approximative quantitative proportions of the phenolic acids in four species of the Oenothera L. genus was determined by the method of TLC and HPLC. In all species of Oenothera L. genus the permanent occurrence of acids: 2-hydroxy-4-metoxybenzoic, salicylic, ferulic, syringic, vanillic, p-coumaric, p-hydroxybenzoic, p-hydroxyphenylacetic, γ-rezorcil, gentysic, protocatechuic, caffeic and gallic has been confirmed. Whereas the other phenolic acids: o-coumaric, o-hydroxyphenylacetic and pirocatechuic were found in some species of the Oenothera L. genus only.

  3. Catalytic production of biofuels (butene oligomers) and biochemicals (tetrahydrofurfuryl alcohol) from corn stover.

    Science.gov (United States)

    Byun, Jaewon; Han, Jeehoon

    2016-07-01

    A strategy is presented that produces liquid hydrocarbon fuels (butene oligomers (BO)) from cellulose (C6) fraction and commodity chemicals (tetrahydrofurfuryl alcohol (THFA)) from hemicellulose (C5) of corn stover based on catalytic conversion technologies using 2-sec-butylphenol (SBP) solvents. This strategy integrates the conversion subsystems based on experimental studies and separation subsystems for recovery of biomass derivatives and SBP solvents. Moreover, a heat exchanger network is designed to reduce total heating requirements to the lowest level, which is satisfied from combustion of biomass residues (lignin and humins). Based on the strategy, this work offers two possible process designs (design A: generating electricity internally vs. design B: purchasing electricity externally), and performs an economic feasibility study for both the designs based on a comparison of the minimum selling price (MSP) of THFA. This strategy with the design B leads to a better MSP of $1.93 per kg THFA. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. The pilus usher controls protein interactions via domain masking and is functional as an oligomer.

    Science.gov (United States)

    Werneburg, Glenn T; Henderson, Nadine S; Portnoy, Erica B; Sarowar, Samema; Hultgren, Scott J; Li, Huilin; Thanassi, David G

    2015-07-01

    The chaperone-usher (CU) pathway assembles organelles termed pili or fimbriae in Gram-negative bacteria. Type 1 pili expressed by uropathogenic Escherichia coli are prototypical structures assembled by the CU pathway. Biogenesis of pili by the CU pathway requires a periplasmic chaperone and an outer-membrane protein termed the usher (FimD). We show that the FimD C-terminal domains provide the high-affinity substrate-binding site but that these domains are masked in the resting usher. Domain masking requires the FimD plug domain, which serves as a switch controlling usher activation. We demonstrate that usher molecules can act in trans for pilus biogenesis, providing conclusive evidence for a functional usher oligomer. These results reveal mechanisms by which molecular machines such as the usher regulate and harness protein-protein interactions and suggest that ushers may interact in a cooperative manner during pilus assembly in bacteria.

  5. Synergistic effects of atmospheric pressure plasma-emitted components on DNA oligomers: a Raman spectroscopic study.

    Science.gov (United States)

    Edengeiser, Eugen; Lackmann, Jan-Wilm; Bründermann, Erik; Schneider, Simon; Benedikt, Jan; Bandow, Julia E; Havenith, Martina

    2015-11-01

    Cold atmospheric-pressure plasmas have become of increasing importance in sterilization processes especially with the growing prevalence of multi-resistant bacteria. Albeit the potential for technological application is obvious, much less is known about the molecular mechanisms underlying bacterial inactivation. X-jet technology separates plasma-generated reactive particles and photons, thus allowing the investigation of their individual and joint effects on DNA. Raman spectroscopy shows that particles and photons cause different modifications in DNA single and double strands. The treatment with the combination of particles and photons does not only result in cumulative, but in synergistic effects. Profilometry confirms that etching is a minor contributor to the observed DNA damage in vitro. Schematics of DNA oligomer treatment with cold atmospheric-pressure plasma. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Copoly(Imide Siloxane) Abhesive Materials with Varied Siloxane Oligomer Length

    Science.gov (United States)

    Wohl, Christopher J.; Atkins, Brad M.; Belcher, Marcus A.; Connell, John W.

    2010-01-01

    Incorporation of PDMS moieties into a polyimide matrix lowered the surface energy resulting in enhanced adhesive interactions. Polyimide siloxane materials were generated using amine-terminated PDMS oligomers of different lengths to study changes in surface migration behavior, phase segregation, mechanical, thermal, and optical properties. These materials were characterized using contact angle goniometry, tensile testing, and differential scanning calorimetry. The surface migration behavior of the PDMS component depended upon the siloxane molecular weight as indicated by distinct relationships between PDMS chain length and advancing water contact angles. Similar correlations were observed for percent elongation values obtained from tensile testing, while the addition of PDMS reduced the modulus. High fidelity topographical modification via laser ablation patterning further reduced the polyimide siloxane surface energy. Initial particulate adhesion testing experiments demonstrated that polyimide siloxane materials exhibited greater abhesive interactions relative to their respective homopolyimides.

  7. Resonant stimulation of Raman scattering from single-crystal thiophene/phenylene co-oligomers

    International Nuclear Information System (INIS)

    Yanagi, Hisao; Marutani, Yusuke; Matsuoka, Naoki; Hiramatsu, Toru; Ishizumi, Atsushi; Sasaki, Fumio; Hotta, Shu

    2013-01-01

    Amplified Raman scattering was observed from single crystals of thiophene/phenylene co-oligomers (TPCOs). Under ns-pulsed excitation, the TPCO crystals exhibited amplified spontaneous emission (ASE) at resonant absorption wavelengths. With increasing excitation wavelength to the 0-0 absorption edge, the stimulated resonant Raman peaks appeared both in the 0-1 and 0-2 ASE band regions. When the excitation wavelength coincided with the 0-1 ASE band energy, the Raman peaks selectively appeared in the 0-2 ASE band. Such unusual enhancement of the 0-2 Raman scattering was ascribed to resonant stimulation via vibronic coupling with electronic transitions in the uniaxially oriented TPCO molecules

  8. Biexcitons in π-conjugated oligomers: Intensity-dependent femtosecond transient-absorption study

    Science.gov (United States)

    Klimov, V. I.; McBranch, D. W.; Barashkov, N.; Ferraris, J.

    1998-09-01

    We report femtosecond transient-absorption (TA) studies of a five-ring oligomer of poly(para-phenylene vinylene) prepared in two different forms: solid-state films and dilute solutions. At high pump fluences, in both types of samples, we observe generation of two-exciton states, which are detected by the evolution of TA spectra and dynamics with increasing pump intensity. In solutions, double excitation of molecules results in the formation of stable biexcitons with enhanced oscillator strength, leading to an increased efficiency of the radiative decay and a superlinear pump dependence of the stimulated emission. In solid-state samples, the two-exciton states are unstable and decay on the subpicosecond time scale due to ultrafast charge transfer, accompanied by generation of interchain excitons.

  9. Biexcitons in {pi}-conjugated oligomers: Intensity-dependent femtosecond transient-absorption study

    Energy Technology Data Exchange (ETDEWEB)

    Klimov, V.I.; McBranch, D.W. [Chemical Science and Technology Division, CST-6, Mail Stop J585, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Barashkov, N.; Ferraris, J. [Chemistry Department, University of Texas, Dallas, Texas 75083 (United States)

    1998-09-01

    We report femtosecond transient-absorption (TA) studies of a five-ring oligomer of poly({ital para}-phenylene vinylene) prepared in two different forms: solid-state films and dilute solutions. At high pump fluences, in both types of samples, we observe generation of two-exciton states, which are detected by the evolution of TA spectra and dynamics with increasing pump intensity. In solutions, double excitation of molecules results in the formation of stable biexcitons with enhanced oscillator strength, leading to an increased efficiency of the radiative decay and a superlinear pump dependence of the stimulated emission. In solid-state samples, the two-exciton states are unstable and decay on the subpicosecond time scale due to ultrafast charge transfer, accompanied by generation of interchain excitons. {copyright} {ital 1998} {ital The American Physical Society}

  10. Delocalization of Coherent Triplet Excitons in Linear Rigid Rod Conjugated Oligomers.

    Science.gov (United States)

    Hintze, Christian; Korf, Patrick; Degen, Frank; Schütze, Friederike; Mecking, Stefan; Steiner, Ulrich E; Drescher, Malte

    2017-02-02

    In this work, the triplet state delocalization in a series of monodisperse oligo(p-phenyleneethynylene)s (OPEs) is studied by pulsed electron paramagnetic resonance (EPR) and pulsed electron nuclear double resonance (ENDOR) determining zero-field splitting, optical spin polarization, and proton hyperfine couplings. Neither the zero-field splitting parameters nor the optical spin polarization change significantly with OPE chain length, in contrast to the hyperfine coupling constants, which showed a systematic decrease with chain length n according to a 2/(1 + n) decay law. The results provide striking evidence for the Frenkel-type nature of the triplet excitons exhibiting full coherent delocalization in the OPEs under investigation with up to five OPE repeat units and with a spin density distribution described by a nodeless particle in the box wave function. The same model is successfully applied to recently published data on π-conjugated porphyrin oligomers.

  11. Optical magnetism and plasmonic Fano resonances in metal-insulator-metal oligomers.

    Science.gov (United States)

    Verre, R; Yang, Z J; Shegai, T; Käll, M

    2015-03-11

    The possibility of achieving optical magnetism at visible frequencies using plasmonic nanostructures has recently been a subject of great interest. The concept is based on designing structures that support plasmon modes with electron oscillation patterns that imitate current loops, that is, magnetic dipoles. However, the magnetic resonances are typically spectrally narrow, thereby limiting their applicability in, for example, metamaterial designs. We show that a significantly broader magnetic response can be realized in plasmonic pentamers constructed from metal-insulator-metal (MIM) sandwich particles. Each MIM unit acts as a magnetic meta-atom and the optical magnetism is rendered quasi-broadband through hybridization of the in-plane modes. We demonstrate that scattering spectra of individual MIM pentamers exhibit multiple Fano resonances and a broad subradiant spectral window that signals the magnetic interaction and a hierarchy of coupling effects in these intricate three-dimensional nanoparticle oligomers.

  12. HPLC-ESI-MS/MS analysis of oxidized di-caffeoylquinic acids generated by metalloporphyrin-catalyzed reactions

    Directory of Open Access Journals (Sweden)

    Michel D. Santos

    2008-01-01

    Full Text Available This paper reports an HPLC-ESI-MS/MS investigation on the oxidation of 3,5- and 4,5- dicaffeoylquinic acid using iron(III tetraphenylporphyrin chloride as catalyst. Two major mono-oxidised products of the quinic acid moiety have been identified for both compounds. However, only the 4,5-derivative afforded two different tri-oxo products. Thus, it seems that the oxidation pattern depends on the number and positions of the caffeic acid moieties present in caffeoylquinic acid molecules.

  13. HPLC-ESI-MS/MS analysis of oxidized di-caffeoylquinic acids generated by metalloporphyrin-catalyzed reactions

    International Nuclear Information System (INIS)

    Santos, Michel D.; Lopes, Norberto P.; Iamamoto, Yassuko

    2008-01-01

    This paper reports an HPLC-ESI-MS/MS investigation on the oxidation of 3,5- and 4,5- dicaffeoylquinic acid using iron(III) tetraphenylporphyrin chloride as catalyst. Two major mono-oxidised products of the quinic acid moiety have been identified for both compounds. However, only the 4,5-derivative afforded two different tri-oxo products. Thus, it seems that the oxidation pattern depends on the number and positions of the caffeic acid moieties present in caffeoylquinic acid molecules. (author)

  14. HPLC-ESI-MS/MS analysis of oxidized di-caffeoylquinic acids generated by metalloporphyrin-catalyzed reactions

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Michel D.; Lopes, Norberto P. [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Ciencias Farmaceuticas. Dept. de Fisica e Quimica]. E-mail: npelopes@fcfrp.usp.br; Iamamoto, Yassuko [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Ciencias Farmaceuticas. Dept. de Quimica

    2008-07-01

    This paper reports an HPLC-ESI-MS/MS investigation on the oxidation of 3,5- and 4,5- dicaffeoylquinic acid using iron(III) tetraphenylporphyrin chloride as catalyst. Two major mono-oxidised products of the quinic acid moiety have been identified for both compounds. However, only the 4,5-derivative afforded two different tri-oxo products. Thus, it seems that the oxidation pattern depends on the number and positions of the caffeic acid moieties present in caffeoylquinic acid molecules. (author)

  15. Amino siloxane oligomer-linked graphene oxide as an efficient adsorbent for removal of Pb(II) from wastewater

    International Nuclear Information System (INIS)

    Luo, Shenglian; Xu, Xiangli; Zhou, Guiyin; Liu, Chengbin; Tang, Yanhong; Liu, Yutang

    2014-01-01

    Graphical abstract: A high performance sorbent, oligomer-linked graphene oxide, was prepared by using oligomeric poly3-aminopropyltriethoxysilane as crosslinking agents. The sorbent could selectively remove Pb(II) with high adsorption capacity. - Highlights: • Oligomer-linked graphene oxide sharply fattened function groups. • The sorbent exhibited high adsorption capacity toward Pb(II). • Pb, Cu and Fe were selectively removed from smelter industrial effluent. • The sorption could be conducted at a wide pH range of about 4.0–7.0. - Abstract: A high performance sorbent, oligomer-linked graphene oxide (GO) composite, was prepared through simple cross-linking reactions between GO sheets and poly3-aminopropyltriethoxysilane (PAS) oligomers as crosslinking agents. The three-dimensional PAS oligomers prevented GO sheets from aggregation, provided foreign molecules with easier access, and introduced a large amount of amino functional groups. The morphology, structure and property of the PAS-GO composite were determined by scanning electron microscope (SEM), transmission electron microscope (TEM), Fourie transform infrared (FTIR), X-ray diffractometer (XRD), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The adsorption performance of PAS-GO was investigated in removing Pb(II) ions from water. Compared to 3-aminopropyltriethoxysilane functionalized GO (AS-GO) which was prepared by the direct reaction between 3-aminopropyltriethoxysilane and GO, PAS-GO exhibited much higher adsorptivity toward Pb(II) with the maximum adsorption capacity of 312.5 mg/g at 303 K and furthermore the maximum adsorption capacity increased with increasing temperature. The adsorption could be conducted in a wide pH range of 4.0–7.0. Importantly, PAS-GO had a priority tendency to adsorb Pb, Cu and Fe from a mixed solution of metal ions, especially from a practical industrial effluent

  16. Oligomers Based on a Weak Hydrogen Bond Network: the Rotational Spectrum of the Tetramer of Difluoromethane

    Science.gov (United States)

    Feng, Gang; Evangelisti, Luca; Caminati, Walther; Cacelli, Ivo; Carbonaro, Laura; Prampolini, Giacomo

    2013-06-01

    Following the investigation of the rotational spectra of three conformers (so-called ``book'', ``prism'' and ``cage'') of the water hexamer, and of some other water oligomers, we report here the rotational spectrum of the tetramer of a freon molecule. The pulse jet Fourier transform microwave (pj-FTMW) spectrum of an isomer of the difluoromethane tetramer has been assigned. This molecular system is made of units of a relatively heavy asymmetric rotor, held together by a network of weak hydrogen bonds. The search of the rotational spectrum has been based on a high-level reference method, the CCSD(T)/CBS protocol. It is interesting to outline that the rotational spectrum of the water tetramer was not observed, probably because the minimum energy structures of this oligomer is effectively nonpolar in its ground states, or because of high energy tunnelling splittings. The rotational spectra of the monomer, dimer, trimer and tetramer of difluoromethane have been assigned in 1952, 1999, 2007, and 2013 (present work), with a decreasing time spacing between the various steps, looking then promising for a continuous and rapid extension of the size limits of molecular systems accessible to MW spectroscopy. C. Pérez, M. T. Muckle, D. P. Zaleski, N. A. Seifert, B. Temelso, G. C. Shields, Z. Kisiel, B. H. Pate, Science {336} (2012) 897. D. R. Lide, Jr., J. Am. Chem. Soc. {74} (1952) 3548. W. Caminati, S. Melandri, P. Moreschini, P. G. Favero, Angew. Chem. Int. Ed. {38} (1999) 2924. S. Blanco, S. Melandri, P. Ottaviani, W. Caminati, J. Am. Chem. Soc. {129} (2007) 2700.

  17. Synthetic oligomer analysis using atmospheric pressure photoionization mass spectrometry at different photon energies.

    Science.gov (United States)

    Desmazières, Bernard; Legros, Véronique; Giuliani, Alexandre; Buchmann, William

    2014-01-15

    Atmospheric pressure photoionization (APPI) followed by mass spectrometric detection was used to ionize a variety of polymers: polyethylene glycol, polymethyl methacrylate, polystyrene, and polysiloxane. In most cases, whatever the polymer or the solvent used (dichloromethane, tetrahydrofuran, hexane, acetone or toluene), only negative ion mode produced intact ions such as chlorinated adducts, with no or few fragmentations, in contrast to the positive ion mode that frequently led to important in-source fragmentations. In addition, it was shown that optimal detection of polymer distributions require a fine tuning of other source parameters such as temperature and ion transfer voltage. Series of mass spectra were recorded in the negative mode, in various solvents (dichloromethane, tetrahydrofuran, hexane, toluene, and acetone), by varying the photon energy from 8eV up to 10.6eV using synchrotron radiation. To these solvents, addition of a classical APPI dopant (toluene or acetone) was not necessary. Courtesy of the synchrotron radiation, it was demonstrated that the photon energy required for an efficient ionization of the polymer was correlated to the ionization energy of the solvent. As commercial APPI sources typically use krypton lamps with energy fixed at 10eV and 10.6eV, the study of the ionization of polymers over a wavelength range allowed to confirm and refine the previously proposed ionization mechanisms. Moreover, the APPI source can efficiently be used as an interface between size exclusion chromatography or reverse phase liquid chromatography and MS for the study of synthetic oligomers. However, the photoionization at fixed wavelength of polymer standards with different molecular weights showed that it was difficult to obtain intact ionized oligomers with molecular weights above a few thousands. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. A hydrogel biosensor for high selective and sensitive detection of amyloid-beta oligomers

    Directory of Open Access Journals (Sweden)

    Sun LP

    2018-02-01

    Full Text Available Liping Sun,1 Yong Zhong,1 Jie Gui,1 Xianwu Wang,1 Xiaorong Zhuang,2 Jian Weng1 1Key Laboratory of Biomedical Engineering of Fujian Province, Research Center of Biomedical Engineering of Xiamen, Department of Biomaterials, College of Materials, Xiamen University, 2Department of Neurology, The Affiliated Zhongshan Hospital of Xiamen University, Xiamen, People’s Republic of China Background: Alzheimer’s disease (AD is a neurodegenerative disorder characterized by progressive cognitive and memory impairment. It is the most common neurological disease that causes dementia. Soluble amyloid-beta oligomers (AβO in blood or cerebrospinal fluid (CSF are the pathogenic biomarker correlated with AD. Methods: A simple electrochemical biosensor using graphene oxide/gold nanoparticles (GNPs hydrogel electrode was developed in this study. Thiolated cellular prion protein (PrPC peptide probe was immobilized on GNPs of the hydrogel electrode to construct an AβO biosensor. Electrochemical impedance spectroscopy was utilized for AβO analysis. Results: The specific binding between AβO and PrPC probes on the hydrogel electrode resulted in an increase in the electron-transfer resistance. The biosensor showed high specificity and sensitivity for AβO detection. It could selectively differentiate AβO from amyloid-beta (Aβ monomers or fibrils. Meanwhile, it was highly sensitive to detect as low as 0.1 pM AβO in artificial CSF or blood plasma. The linear range for AβO detection is from 0.1 pM to 10 nM. Conclusion: This biosensor could be used as a cost-effective tool for early diagnosis of AD due to its high electrochemical performance and bionic structure. Keywords: Alzheimer’s disease, amyloid-beta oligomer, graphene, gold nanoparticles, biosensor

  19. Molecular Dynamics Simulations of Silica Nanoparticles Grafted with Poly(ethylene oxide) Oligomer Chains

    KAUST Repository

    Hong, Bingbing

    2012-03-01

    A molecular model of silica nanoparticles grafted with poly(ethylene oxide) oligomers has been developed for predicting the transport properties of nanoparticle organic-hybrid materials (NOHMs). Ungrafted silica nanoparticles in a medium of poly(ethylene oxide) oligomers were also simulated to clarify the effect of grafting on the dynamics of nanoparticles and chains. The model approximates nanoparticles as solid spheres and uses a united-atom representation for chains, including torsional and bond-bending interactions. The calculated viscosities from Green-Kubo relationships and temperature extrapolation are of the same order of magnitude as experimental data but show a smaller activation energy relative to real NOHMs systems. Grafted systems have higher viscosities, smaller diffusion coefficients, and slower chain dynamics than the ungrafted ones at high temperatures. At lower temperatures, grafted systems exhibit faster dynamics for both nanoparticles and chains relative to ungrafted systems, because of lower aggregation of particles and enhanced correlations between nanoparticles and chains. This agrees with the experimental observation that NOHMs have liquidlike behavior in the absence of a solvent. For both grafted and ungrafted systems at low temperatures, increasing chain length reduces the volume fraction of nanoparticles and accelerates the dynamics. However, at high temperatures, longer chains slow down nanoparticle diffusion. From the Stokes-Einstein relationship, it was determined that the coarse-grained treatment of nanoparticles leads to slip on the nanoparticle surfaces. Grafted systems obey the Stokes-Einstein relationship over the temperature range simulated, but ungrafted systems display deviations from it. © 2012 American Chemical Society.

  20. Synergistic influence of phosphorylation and metal ions on tau oligomer formation and coaggregation with α-synuclein at the single molecule level

    Directory of Open Access Journals (Sweden)

    Nübling Georg

    2012-07-01

    Full Text Available Abstract Background Fibrillar amyloid-like deposits and co-deposits of tau and α-synuclein are found in several common neurodegenerative diseases. Recent evidence indicates that small oligomers are the most relevant toxic aggregate species. While tau fibril formation is well-characterized, factors influencing tau oligomerization and molecular interactions of tau and α-synuclein are not well understood. Results We used a novel approach applying confocal single-particle fluorescence to investigate the influence of tau phosphorylation and metal ions on tau oligomer formation and its coaggregation with α-synuclein at the level of individual oligomers. We show that Al3+ at physiologically relevant concentrations and tau phosphorylation by GSK-3β exert synergistic effects on the formation of a distinct SDS-resistant tau oligomer species even at nanomolar protein concentration. Moreover, tau phosphorylation and Al3+ as well as Fe3+ enhanced both formation of mixed oligomers and recruitment of α-synuclein in pre-formed tau oligomers. Conclusions Our findings provide a new perspective on interactions of tau phosphorylation, metal ions, and the formation of potentially toxic oligomer species, and elucidate molecular crosstalks between different aggregation pathways involved in neurodegeneration.

  1. Phenolic acids potentiate colistin-mediated killing of Acinetobacter baumannii by inducing redox imbalance.

    Science.gov (United States)

    Ajiboye, Taofeek O; Skiebe, Evelyn; Wilharm, Gottfried

    2018-05-01

    Phenolic acids with catechol groups are good prooxidants because of their low redox potential. In this study, we provided data showing that phenolic acids, caffeic acid, gallic acid and protocatechuic acid, enhanced colistin-mediated bacterial death by inducing redox imbalance. The minimum inhibitory concentrations of these phenolic acids against Acinetobacter baumannii AB5075 were considerably lowered for ΔsodB and ΔkatG mutants. Checkerboard assay shows synergistic interactions between colistin and phenolic acids. The phenolic acids exacerbated colistin-induced oxidative stress in A. baumannii AB5075 through increased superoxide anion generation, NAD + /NADH and ADP/ATP ratio. In parallel, the level of reduced glutathione was significantly lowered. We conclude that phenolic acids potentiate colistin-induced oxidative stress in A. baumannii AB5075 by increasing ROS generation, energy metabolism and electron transport chain activity with a concomitant decrease in glutathione. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  2. Antifungal activity of secondary plant metabolites from potatoes (Solanum tuberosum L.): Glycoalkaloids and phenolic acids show synergistic effects.

    Science.gov (United States)

    Sánchez-Maldonado, A F; Schieber, A; Gänzle, M G

    2016-04-01

    To study the antifungal effects of the potato secondary metabolites α-solanine, α-chaconine, solanidine and caffeic acid, alone or combined. Resistance to glycoalkaloids varied among the fungal species tested, as derived from minimum inhibitory concentrations assays. Synergistic antifungal activity between glycoalkaloids and phenolic compounds was found. Changes in the fluidity of fungal membranes caused by potato secondary plant metabolites were determined by calculation of the generalized polarization values. The results partially explained the synergistic effect between caffeic acid and α-chaconine and supported findings on membrane disruption mechanisms from previous studies on artificial membranes. LC/MS analysis was used to determine variability and relative amounts of sterols in the different fungal species. Results suggested that the sterol pattern of fungi is related to their resistance to potato glycoalkaloids and to their taxonomy. Fungal resistance to α-chaconine and possibly other glycoalkaloids is species dependent. α-Chaconine and caffeic acid show synergistic antifungal activity. The taxonomic classification and the sterol pattern play a role in fungal resistance to glycoalkaloids. Results improve the understanding of the antifungal mode of action of potato secondary metabolites, which is essential for their potential utilization as antifungal agents in nonfood systems. © 2016 The Society for Applied Microbiology.

  3. Co-existence of two different α-synuclein oligomers with different core structures determined by hydrogen/deuterium exchange mass spectrometry

    DEFF Research Database (Denmark)

    Paslawski, Wojciech; Mysling, Simon; Thomsen, Karen

    2014-01-01

    Neurodegenerative disorders are characterized by the formation of protein oligomers and amyloid fibrils, which in the case of Parkinson's disease involves the protein α-synuclein (αSN). Cytotoxicity is mainly associated with the oligomeric species, but we still know little about their assembly...... are protected from exchange with D2 O until they dissociate into monomeric αSN by EX1 exchange kinetics. Fewer residues are protected against exchange in oligomer type II, but this type does not revert to αSN monomers. Both oligomers are protected in the core sequence Y39-A89. Based on incubation studies...

  4. Programmable Oligomers Targeting 5′-GGGG-3′ in the Minor Groove of DNA and NF-κB Binding Inhibition

    Science.gov (United States)

    Chenoweth, David M.; Poposki, Julie A.; Marques, Michael A.; Dervan, Peter B.

    2009-01-01

    A series of hairpin oligomers containing benzimidazole (Bi) and imidazopyridine (Ip) rings were synthesized and screened to target 5′-WGGGGW-3′, a core sequence in the DNA binding site of NF-κB, a prolific transcription factor important in biology and disease. Five Bi and Ip containing oligomers bound to the 5′-WGGGGW-3′ site with high affinity. One of the oligomers (Im-Im-Im-Im-γ-PyBi-PyBi-β-Dp) was able to inhibit DNA binding by the transcription factor NF-κB. PMID:17095230

  5. Acidic-alkaline ferulic acid esterase from Chaetomium thermophilum var. dissitum: Molecular cloning and characterization of recombinant enzyme expressed in Pichia pastoris

    DEFF Research Database (Denmark)

    Dotsenko, Gleb; Tong, Xiaoxue; Pilgaard, Bo

    2016-01-01

    A novel ferulic acid esterase encoding gene CtFae, was successfully cloned from a highly esterase active strain of the thermophile ascomycetous fungus Chaetomium thermophilum var. dissitum; the gene was heterologously expressed in Pichia pastoris KM71H. The recombinant enzyme (CtFae) was purified...... to homogeneity and subsequently characterized. CtFae was active towards synthetic esters of ferulic, p-coumaric, and caffeic acids, as well as towards wide range of p-nitrophenyl substrates. Its temperature and pH optima were 55 °C and pH 6.0, respectively. Enzyme rare features were broad pH optimum, high...

  6. In situ stabilizer formation from methacrylic acid macromonomers in emulsion polymerization

    NARCIS (Netherlands)

    Schreur-Piet, Ingeborg; Heuts, Johan P.A.

    2017-01-01

    Oligomers of methacrylic acid containing a propenyl ω-endgroup (i.e. MAA-macromonomers) were synthesized by cobalt-mediated catalytic chain transfer polymerization and used as precursors to stabilizers in emulsion polymerization. It was found that only in those polymerizations in which these

  7. Enthalpies of solvation of ethylene oxide oligomers CH{sub 3}O(CH{sub 2}CH{sub 2}O){sub n}CH{sub 3} (n = 1 to 4) in different H-bonding solvents: Methanol, chloroform, and water. Group contribution method as applied to the polar oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Barannikov, Vladimir P., E-mail: vpb@isc-ras.ru [Institute of Solution Chemistry, Russian Academy of Sciences, Academicheskaya Str. 1, Ivanovo 153045 (Russian Federation); Guseynov, Sabir S.; Vyugin, Anatoliy I. [Institute of Solution Chemistry, Russian Academy of Sciences, Academicheskaya Str. 1, Ivanovo 153045 (Russian Federation)

    2011-12-15

    Highlights: > Solvation enthalpy is found for ethylene oxide oligomers in chloroform and methanol. > Coefficients of solute-solute interaction are determined for oligomers in methanol. > Enthalpies of hydrogen bonding of oligomers with chloroform and water are estimated. > Additivity scheme is developed for describing enthalpies of solvation of oligomers. - Abstract: The enthalpies of solution and solvation of ethylene oxide oligomers CH{sub 3}O(CH{sub 2}CH{sub 2}O){sub n}CH{sub 3} (n = 1 to 4) in methanol and chloroform have been determined from calorimetric measurements at T = 298.15 K. The enthalpic coefficients of pairwise solute-solute interaction for methanol solutions have been calculated. The enthalpic characteristics of the oligomers in methanol, chloroform, water and tetrachloromethane have been compared. The hydrogen bonding of the oligomers with chloroform and water molecules is exhibited in the values of solvation enthalpy and coefficient of solute-solute interaction. This effect is not observed for methanol solvent. The thermochemical data evidence an existence of multi-centred hydrogen bonds in associates of polyethers with the solvent molecules. Enthalpies of hydrogen bonding of the oligomers with chloroform and water have been estimated. The additivity scheme has been developed to describe the enthalpies of solvation of ethylene oxide oligomers, unbranched monoethers and n-alkanes in chloroform, methanol, water, and tetrachloromethane. The correction parameters for contribution of repeated polar groups and correction term for methoxy-compounds have been introduced. The obtained group contributions permit to describe the enthalpies of solvation of unbranched monoethers and ethylene oxide oligomers in the solvents with standard deviation up to 0.6 kJ . mol{sup -1}. The values of group contributions and corrections are strongly influenced by solvent properties.

  8. A theory for the origin of a self-replicating chemical system. I - Natural selection of the autogen from short, random oligomers

    Science.gov (United States)

    White, D. H.

    1980-01-01

    A general theory is presented for the origin of a self-replicating chemical system, termed an autogen, which is capable of both crude replication and translation (protein synthesis). The theory requires the availability of free energy and monomers to the system, a significant background low-yield synthesis of kinetically stable oligopeptides and oligonucleotides, the localization of the oligomers, crude oligonucleotide selectivity of amino acids during oligopeptide synthesis, crude oligonucleotide replication, and two short peptide families which catalyze replication and translation, to produce a localized group of at least one copy each of two protogenes and two protoenzymes. The model posits a process of random oligomerization, followed by the random nucleation of functional components and the rapid autocatalytic growth of the functioning autogen to macroscopic amounts, to account for the origin of the first self-replicating system. Such a process contains steps of such high probability and short time periods that it is suggested that the emergence of an autogen in a laboratory experiment of reasonable time scale may be possible.

  9. Lectin conjugates as biospecific contrast agents for MRI. Coupling of Lycopersicon esculentum agglutinin to linear water-soluble DTPA-loaded oligomers.

    Science.gov (United States)

    Pashkunova-Martic, Irena; Kremser, Christian; Galanski, Markus; Schluga, Petra; Arion, Vladimir; Debbage, Paul; Jaschke, Werner; Keppler, Bernhard

    2011-06-01

    Magnetic resonance imaging (MRI) requires synthesis of contrast media bearing targeting groups and numerous gadolinium chelating groups generating high relaxivity. This paper explores the results of linking the gadolinium chelates to the targeting group, a protein molecule, via various types of linkers. Polycondensates of diethylenetriaminepentaacetic acid (DTPA) with either diols or diamines were synthesised and coupled to the targeting group, a lectin (Lycopersicon esculentum agglutinin, tomato lectin) which binds with high affinity to specific oligosaccharide configurations in the endothelial glycocalyx. The polycondensates bear up to four carboxylic groups per constitutive unit. Gd-chelate bonds are created through dative interactions with the unshared pair of electrons on each oxygen and nitrogen atom on DTPA. This is mandatory for complexation of Gd(III) and avoidance of the severe toxicity of free gadolinium ions. The polymer-DTPA compounds were characterised by (1)H NMR and mass spectrometry. The final lectin-DTPA-polycondensate conjugates were purified by fast protein liquid chromatography (FPLC). The capacity for specific binding was assessed, and the MRI properties were examined in order to evaluate the use of these oligomers as components of selective perfusional contrast agents.

  10. Catalysis of the Oligomerization of O-Phospho-Serine, Aspartic Acid, or Glutamic Acid by Cationic Micelles

    Science.gov (United States)

    Bohler, Christof; Hill, Aubrey R., Jr.; Orgel, Leslie E.

    1996-01-01

    Treatment of relatively concentrated aqueous solutions of 0-phospho-serine (50 mM), aspartic acid (100 mM) or glutamic acid (100 mM) with carbonyldiimidazole leads to the formation of an activated intermediate that oligomerizes efficiently. When the concentration of amino acid is reduced tenfold, few long oligomers can be detected. Positively-charged cetyltrimethyl ammonium bromide micelles concentrate the negatively-charged activated intermediates of the amino acids at their surfaces and catalyze efficient oligomerization even from dilute solutions.

  11. Effect of Side Chains on Molecular Conformation of Anthracene-Ethynylene-Phenylene-Vinylene Oligomers: A Comparative Density Functional Study With and Without Dispersion Interaction.

    Science.gov (United States)

    Dong, Chuanding; Hoppe, Harald; Beenken, Wichard J D

    2016-06-02

    Using density functional calculations with and without dispersion interaction, we studied the effects of linear octyl and branched 2-ethylhexyl side chains on the oligomer conformation of the conjugated copolymer poly(p-anthracene-ethynylene)-alt-poly(p-phenylene-vinylene). With dispersion included, the branched side chains can cause significant bending of the oligomer backbone, while without dispersion they induce mainly torsional disorder. The oligomers with mainly linear side chains keep good planarity when optimized with and without dispersion. Despite their dramatically different conformations, the calculated absorption spectra of the oligomers with various side chain combinations are very similar, indicating that the conformation of the copolymer is not the main reason for the experimentally observed different spectra of ordered and disordered phases.

  12. Concentrations of oligomers and polymers of proanthocyanidins in red and purple rice bran and their relationships to total phenolics, flavonoids, antioxidant capacity and whole grain color

    Science.gov (United States)

    Proanthocyanidins, a flavonoids subgroup, are proposed to have chronic disease modulation properties. With the eventual goal of enhancing rice phytonutrient concentrations, we investigated the genotypic variation of the concentrations of individual oligomers and polymers of proanthocyanidins in dark...

  13. Astrocyte Transforming Growth Factor Beta 1 Protects Synapses against Aβ Oligomers in Alzheimer's Disease Model.

    Science.gov (United States)

    Diniz, Luan Pereira; Tortelli, Vanessa; Matias, Isadora; Morgado, Juliana; Bérgamo Araujo, Ana Paula; Melo, Helen M; Seixas da Silva, Gisele S; Alves-Leon, Soniza V; de Souza, Jorge M; Ferreira, Sergio T; De Felice, Fernanda G; Gomes, Flávia Carvalho Alcantara

    2017-07-12

    Alzheimer's disease (AD) is characterized by progressive cognitive decline, increasingly attributed to neuronal dysfunction induced by amyloid-β oligomers (AβOs). Although the impact of AβOs on neurons has been extensively studied, only recently have the possible effects of AβOs on astrocytes begun to be investigated. Given the key roles of astrocytes in synapse formation, plasticity, and function, we sought to investigate the impact of AβOs on astrocytes, and to determine whether this impact is related to the deleterious actions of AβOs on synapses. We found that AβOs interact with astrocytes, cause astrocyte activation and trigger abnormal generation of reactive oxygen species, which is accompanied by impairment of astrocyte neuroprotective potential in vitro We further show that both murine and human astrocyte conditioned media (CM) increase synapse density, reduce AβOs binding, and prevent AβO-induced synapse loss in cultured hippocampal neurons. Both a neutralizing anti-transforming growth factor-β1 (TGF-β1) antibody and siRNA-mediated knockdown of TGF-β1, previously identified as an important synaptogenic factor secreted by astrocytes, abrogated the protective action of astrocyte CM against AβO-induced synapse loss. Notably, TGF-β1 prevented hippocampal dendritic spine loss and memory impairment in mice that received an intracerebroventricular infusion of AβOs. Results suggest that astrocyte-derived TGF-β1 is part of an endogenous mechanism that protects synapses against AβOs. By demonstrating that AβOs decrease astrocyte ability to protect synapses, our results unravel a new mechanism underlying the synaptotoxic action of AβOs in AD. SIGNIFICANCE STATEMENT Alzheimer's disease is characterized by progressive cognitive decline, mainly attributed to synaptotoxicity of the amyloid-β oligomers (AβOs). Here, we investigated the impact of AβOs in astrocytes, a less known subject. We show that astrocytes prevent synapse loss induced by A

  14. Synthesis and optoelectronic properties of a monodispersed macrocycle oligomer consisting of three triarylamine units

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Qinggang, E-mail: gangq0172@163.com [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, College of Environmental Science and Engineering, Nanjing University of Information Science and Technology, 219 Ningliu Road, Pukou District, Nanjing 210044 (China); Qian, Haiyan, E-mail: qianhaiy@163.com [College of Material Science and Technology, Nanjing University of Technology, 5 Xinmofan Road, Nanjing 210009 (China); Zhou, Yonghui; Li, Jun; Xiao, Huining [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, College of Environmental Science and Engineering, Nanjing University of Information Science and Technology, 219 Ningliu Road, Pukou District, Nanjing 210044 (China)

    2012-08-15

    A monodispersed macrocyclic oligomer constructed by three triarylmine units ((TPAT){sub 3}) was designed and readily synthesized from the monomer of 3-(4 Prime -(phenyl(4 Double-Prime -methylphenyl)amino)-phenyl)pentan-3-ol (TPAT) by means of a simple Friedel-Crafts alkylation reaction. The structure of the resultant macrocycle was examined using FT-IR, NMR and MALDI-TOF mass spectroscopy. Compared with 1,10-bis(di-4-tolylaminophenyl) cyclohexane (TAPC) and tri-p-tolylamine (TTA), (TPAT){sub 3} possesses the three-dimensional chair conformation and the higher T{sub g}. In the photoluminescence (PL) spectrum of (TPAT){sub 3} film, there are no excimer emission peaks in the range of 400-550 nm region as those of TAPC and TTA. Besides an EL peak at 386 nm, the single-layer device occured only the 438 nm excimer emission peak, whose intensity increased with the excitation voltage increase. Using 1,3,5-Tris(N-phenylbenzimidazol-2-yl)-benzene (TPBI) as the electron-transporting layer, the resulting double-layer device ITO/(TPAT){sub 3} (40 nm)/TPBI (40 nm)/Mg:Ag (10:1; 50 nm)/Ag (100 nm) only exhibited a 438 nm maximum symmetrical emission peak under an excitation voltage of 14 V. However, as the applied voltage was increased from 14 V to 19 V, the intensity of the symmetrical curve with a 468 nm peak from exciplex emission gets stronger and stronger. In fact, the resultant emission curve was asymmetrical, due to the overlap of two symmetrical curves with 438 nm and 468 nm peaks, respectively. The maximum luminance and luminous efficiency are 2240 cd m{sup -2} at 18.8 V and 1.73 cd A{sup -1} at 1878 cd m{sup -2} (13.9 V). Highlights: Black-Right-Pointing-Pointer The monodispersed macrocyclic oligomer constructed by three triarylamine units was synthesized and characterized. Black-Right-Pointing-Pointer The PL of (TPAT){sub 3} film does not emerge TAPC and TTA's emission peaks of over 400 nm region. Black-Right-Pointing-Pointer The 438 nm emission peak was found from

  15. Laccase-Catalyzed Synthesis of Low-Molecular-Weight Lignin-Like Oligomers and their Application as UV-Blocking Materials.

    Science.gov (United States)

    Lim, Jieyan; Sana, Barindra; Krishnan, Ranganathan; Seayad, Jayasree; Ghadessy, Farid J; Jana, Satyasankar; Ramalingam, Balamurugan

    2018-02-02

    The laccase-catalyzed oxidative polymerization of monomeric and dimeric lignin model compounds was carried out with oxygen as the oxidant in aqueous medium. The oligomers were characterized by using gel permeation chromatography (GPC) and matrix-assisted laser desorption ionization time-of-flight mass spectroscopy (MALDI-TOF MS) analysis. Oxidative polymerization led to the formation of oligomeric species with a number-average molecular weight (M n ) that ranged from 700 to 2300 Da with a low polydispersity index. Spectroscopic analysis provided insight into the possible modes of linkages present in the oligomers, and the oligomerization is likely to proceed through the formation of C-C linkages between phenolic aromatic rings. The oligomers were found to show good UV light absorption characteristics with high molar extinction coefficient (5000-38 000 m -1  cm -1 ) in the UV spectral region. The oligomers were blended independently with polyvinyl chloride (PVC) by using solution blending to evaluate the compatibility and UV protection ability of the oligomers. The UV/Vis transmittance spectra of the oligomer-embedded PVC films indicated that these lignin-like oligomers possessed a notable ability to block UV light. In particular, oligomers obtained from vanillyl alcohol and the dimeric lignin model were found to show good photostability in accelerated UV weathering experiments. The UV-blocking characteristics and photostability were finally compared with the commercial low-molecular-weight UV stabilizer 2,4-dihydroxybenzophenone. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Phase Morphology and Mechanical Properties of Cyclic Butylene Terephthalate Oligomer-Containing Rubbers: Effect of Mixing Temperature

    OpenAIRE

    Hal?sz, Istv?n Zolt?n; B?r?ny, Tam?s

    2016-01-01

    In this work, the effect of mixing temperature (Tmix) on the mechanical, rheological, and morphological properties of rubber/cyclic butylene terephthalate (CBT) oligomer compounds was studied. Apolar (styrene butadiene rubber, SBR) and polar (acrylonitrile butadiene rubber, NBR) rubbers were modified by CBT (20 phr) for reinforcement and viscosity reduction. The mechanical properties were determined in tensile, tear, and dynamical mechanical analysis (DMTA) tests. The CBT-caused viscosity cha...

  17. Nanoscale Synaptic Membrane Mimetic Allows Unbiased High Throughput Screen That Targets Binding Sites for Alzheimer?s-Associated A? Oligomers

    OpenAIRE

    Wilcox, Kyle C.; Marunde, Matthew R.; Das, Aditi; Velasco, Pauline T.; Kuhns, Benjamin D.; Marty, Michael T.; Jiang, Haoming; Luan, Chi-Hao; Sligar, Stephen G.; Klein, William L.

    2015-01-01

    Despite their value as sources of therapeutic drug targets, membrane proteomes are largely inaccessible to high-throughput screening (HTS) tools designed for soluble proteins. An important example comprises the membrane proteins that bind amyloid β oligomers (AβOs). AβOs are neurotoxic ligands thought to instigate the synapse damage that leads to Alzheimer's dementia. At present, the identities of initial AβO binding sites are highly uncertain, largely because of extensive protein-protein int...

  18. In vitro synthesis and purification of PhIP-deoxyguanosine and PhIP-DNA oligomer covalent complexes

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, J.

    1994-12-01

    2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a heterocyclic amine compound formed when meats are cooked at high temperatures. PhIP damages DNA by forming covalent complexes with DNA carcinogen. In an effort to understand how the binding of PhIP to DNA may cause cancer, it is important to characterize the structures of PhIP-damaged DNA molecules. Our HPLC data support fluorescence and {sup 32}P Post-labeling studies which indicate the formation of several species of 2{prime}deoxyguanosine-(dG) or oligodeoxynucleotide-PhIP adducts. The reaction of PhIP with dG resulted in a reddish precipitate that was likely the major adduct, N-(deoxyguanosin-8-yl)-PhIP (dG-C8-PhIP) adduct, with a more polar adduct fraction remaining in the supernatant. Reversed-phase HPLC analysis of the adducts in the supernatant revealed the existence of species of much shorter retention times than the dG-C8-PhIP adduct, confirming that these species are more polar than dG-C8-PhIP. At least four adducts were formed in the reaction of PhIP with DNA oligomer. HPLC analysis of the PhIP-DNA oligomer supernatant after butanol extractions revealed four unresolved peaks which spectra had maximum wavelengths between 340 and 360 nm. Though adduct peaks were not completely resolved, there was {approximately}3 minutes interval between the DNA oligomer peak and the adduct peaks. Furthermore, fluorescence emission data of the DNA oligomer-PhIP adduct solution show heterogeneous binding. The more polar PhIP adducts were fraction-collected and their structures will be solved by nuclear magnetic resonance or x-ray crystallography.

  19. Structure-Activity Relationships in the Cytoprotective Effect of Caffeic Acid Phenethyl Ester (CAPE) and Fluorinated Derivatives: Effects on Heme Oxygenase-1 Induction and Antioxidant Activities

    Science.gov (United States)

    2010-03-09

    Hishikawa, K., Nakaki, T., Fujita, T., 2005. Oral flavonoid supplementation attenuates atherosclerosis development in apolipoprotein E-deficient mice... flavonoids . Free Radical Biology & Medicine 20, 331–342. Wakabayashi, N., Dinkova-Kostova, A.T., Holtzclaw, W.D., Kang, M.I., Kobayashi, A., Yamamoto, M

  20. The pro-fibrotic properties of transforming growth factor on human fibroblasts are counteracted by caffeic acid by inhibiting myofibroblast formation and collagen synthesis

    NARCIS (Netherlands)

    Mia, Masum M.; Bank, Ruud A.

    Fibrosis is a chronic disorder affecting many organs. A universal process in fibrosis is the formation of myofibroblasts and the subsequent collagen deposition by these cells. Transforming growth factor beta1 (TGF beta 1) plays a major role in the formation of myofibroblasts, e.g. by activating

  1. Natural Product Total Synthesis in the Organic Laboratory: Total Synthesis of Caffeic Acid Phenethyl Ester (CAPE), a Potent 5-Lipoxygenase Inhibitor from Honeybee Hives

    Science.gov (United States)

    Touaibia, Mohamed; Guay, Michel

    2011-01-01

    Natural products play a critical role in modern organic synthesis and learning synthetic techniques is an important component of the organic laboratory experience. In addition to traditional one-step organic synthesis laboratories, a multistep natural product synthesis is an interesting experiment to challenge students. The proposed three-step…

  2. Nitrogen Limited Red and Green Leaf Lettuce Accumulate Flavonoid Glycosides, Caffeic Acid Derivatives, and Sucrose while Losing Chlorophylls, ?-Carotene and Xanthophylls

    OpenAIRE

    Becker, Christine; Urli?, Branimir; Juki? ?pika, Maja; Kl?ring, Hans-Peter; Krumbein, Angelika; Baldermann, Susanne; Goreta Ban, Smiljana; Perica, Slavko; Schwarz, Dietmar

    2015-01-01

    Reduction of nitrogen application in crop production is desirable for ecological and health-related reasons. Interestingly, nitrogen deficiency can lead to enhanced concentrations of polyphenols in plants. The reason for this is still under discussion. The plants' response to low nitrogen concentration can interact with other factors, for example radiation intensity. We cultivated red and green leaf lettuce hydroponically in a Mediterranean greenhouse, supplying three different levels of nitr...

  3. Synthesis, optical properties and supramolecular order of π-conjugated 2,5-di(alcoxy)phenyleneethynylene oligomers

    Science.gov (United States)

    Castruita, Griselda; Arias, Eduardo; Moggio, Ivana; Pérez, Fátima; Medellín, Diana; Torres, Román; Ziolo, Ronald; Olivas, Amelia; Giorgetti, Emilia; Muniz-Miranda, Maurizio

    2009-11-01

    Two series of 2,5-di(alkoxy)phenyleneethynylene oligomers were synthesized by Sonogashira-Heck coupling reaction. The chemical structure was corroborated by 1H, 13C, APT, DEPT-135 NMR, Raman, FTIR and MALDI-TOF mass spectrometry. The chemical structure of the molecules has been varied in order to study the effect on the physicochemical and optoelectronic properties of the different chain lengths of the lateral substituents (dodecanoxy and butoxy), of different terminal groups (H, Br and I), of different chain length (3, 5 and 7 repeat units in the main conjugated backbone). The thermal properties were analyzed by DSC, TGA and by temperature-dependent X-ray diffraction. The diffraction studies of the oligomers revealed a crystalline behavior for the butoxy series, while for the dodecanoxy series the X-ray patterns are consistent with a supramolecular organization formed of randomly distributed crystalline domains that exhibit a periodic structure at small angles, indicating the presence of a lamellar order. The optical properties can be modulated within a series by increasing the length of the conjugated oligomer chain. On the contrary, neither the length of the alkoxy substituents nor the terminal groups have effect on the shape of the absorption and emission spectra.

  4. Disrupting self-assembly and toxicity of amyloidogenic protein oligomers by "molecular tweezers" - from the test tube to animal models.

    Science.gov (United States)

    Attar, Aida; Bitan, Gal

    2014-01-01

    Despite decades of research, therapy for diseases caused by abnormal protein folding and aggregation (amyloidoses) is limited to treatment of symptoms and provides only temporary and moderate relief to sufferers. The failure in developing successful disease-modifying drugs for amyloidoses stems from the nature of the targets for such drugs - primarily oligomers of amyloidogenic proteins, which are distinct from traditional targets, such as enzymes or receptors. The oligomers are metastable, do not have well-defined structures, and exist in dynamically changing mixtures. Therefore, inhibiting the formation and toxicity of these oligomers likely will require out-of-the-box thinking and novel strategies. We review here the development of a strategy based on targeting the combination of hydrophobic and electrostatic interactions that are key to the assembly and toxicity of amyloidogenic proteins using lysine (K)-specific "molecular tweezers" (MTs). Our discussion includes a survey of the literature demonstrating the important role of K residues in the assembly and toxicity of amyloidogenic proteins and the development of a lead MT derivative called CLR01, from an inhibitor of protein aggregation in vitro to a drug candidate showing effective amelioration of disease symptoms in animal models of Alzheimer's and Parkinson's diseases.

  5. Dermal oncogenicity bioassays of monofunctional and multifunctional acrylates and acrylate-based oligomers.

    Science.gov (United States)

    DePass, L R; Maronpot, R R; Weil, C S

    1985-01-01

    Several important components of photocurable coatings were studied for dermal tumorigenic activity by repeated application to the skin of mice. The substances tested were 2-ethylhexyl acrylate (EHA) and methylcarbamoyloxyethyl acrylate (MCEA) (monomers); neopentyl glycol diacrylate (NPGDA), esterdiol-204-diacrylate (EDDA), and pentaerythritol tri(tetra)acrylate (PETA) (cross-linkers); and three acrylated urethane oligomers. For each bioassay, 40 C3H/HeJ male mice were dosed 3 times weekly on the dorsal skin for their lifetime with the highest dose of the test agent that caused no local irritation or reduction in body weight gain. Two negative control groups received acetone (diluent) only. A positive control group received 0.2% methylcholanthrene (MC). NPGDA and EHA had significant tumorigenic activity with tumor yields of eight and six tumor-bearing mice (three and two malignancies), respectively. The MC group had 34 mice with carcinomas and 1 additional mouse with a papilloma. MCEA had no dermal tumorigenic activity but resulted in early mortality. No skin tumors in the treatment area were observed in the other groups. Additional studies will be necessary to elucidate possible relationships between structure and tumorigenic activity for the acrylates.

  6. Amplified release through the stimulus triggered degradation of self-immolative oligomers, dendrimers, and linear polymers.

    Science.gov (United States)

    Wong, Andrew D; DeWit, Matthew A; Gillies, Elizabeth R

    2012-08-01

    In recent years, numerous delivery systems based on polymers, dendrimers, and nano-scale assemblies have been developed to improve the properties of drug molecules. In general, for the drug molecules to be active, they must be released from these delivery systems, ideally in a selective manner at the therapeutic target. As the changes in physiological conditions are relatively subtle from one tissue to another and the concentrations of specific enzymes are often quite low, a release strategy involving the amplification of a biological signal is particularly attractive. This article describes the development of oligomers, dendrimers, and linear polymers based on self-immolative spacers. This new class of molecules is designed to undergo a cascade of intramolecular reactions in response to the cleavage of a trigger moiety, resulting in molecular fragmentation and the release of multiple reporter or drug molecules. Progress in the development of these materials as drug delivery vehicles and sensors will be highlighted. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. Molecular solar thermal energy storage in photoswitch oligomers increases energy densities and storage times.

    Science.gov (United States)

    Mansø, Mads; Petersen, Anne Ugleholdt; Wang, Zhihang; Erhart, Paul; Nielsen, Mogens Brøndsted; Moth-Poulsen, Kasper

    2018-05-16

    Molecular photoswitches can be used for solar thermal energy storage by photoisomerization into high-energy, meta-stable isomers; we present a molecular design strategy leading to photoswitches with high energy densities and long storage times. High measured energy densities of up to 559 kJ kg -1 (155 Wh kg -1 ), long storage lifetimes up to 48.5 days, and high quantum yields of conversion of up to 94% per subunit are demonstrated in norbornadiene/quadricyclane (NBD/QC) photo-/thermoswitch couples incorporated into dimeric and trimeric structures. By changing the linker unit between the NBD units, we can at the same time fine-tune light-harvesting and energy densities of the dimers and trimers so that they exceed those of their monomeric analogs. These new oligomers thereby meet several of the criteria to be met for an optimum molecule to ultimately enter actual devices being able to undergo closed cycles of solar light-harvesting, energy storage, and heat release.

  8. Roasting conditions for preserving cocoa flavan-3-ol monomers and oligomers: interesting behaviour of Criollo clones.

    Science.gov (United States)

    De Taeye, Cédric; Bodart, Marie; Caullet, Gilles; Collin, Sonia

    2017-09-01

    Cocoa bean roasting is important for creating the typical chocolate aroma through Maillard reactions, but it is also a key step deleterious to the polyphenol content and profile. Compared with usual roasting at 150 °C, keeping the beans for 30 min at 120 °C or for 1 h at 90 °C proved much better for preventing strong degradation of native P1, P2 and P3 flavan-3-ols in cocoa (shown for Forastero, Trinitatio and Criollo cultivars). Surprisingly, Cuban, Mexican and Malagasy white-seeded beans behaved atypically when roasted for 30 min at 150 °C, releasing a pool of catechin. Enantiomeric chromatographic separation proved that this pool contained mainly (-)-catechin issued from (-)-epicatechin by epimerisation. As the (-)-epicatechin content remained relatively constant through Criollo bean roasting, flavan-3-ol monomers must have been regenerated from oligomers. This emergence of (-)-catechin in Criollo beans only, reported here for the first time, could be due to increased flavan-3-ol monomer stability in the absence of anthocyanidin-derived products. The degradation rate of flavan-3-ols through roasting is higher in cocoa beans containing anthocyani(di)ns. The liberation of a pool of (-)-catechin when submitted to roasting at 150 °C allows to distinguish white-seeded cultivars. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  9. Equilibrium polymerization of cyclic carbonate oligomers. III. Chain branching and the gel transition

    Science.gov (United States)

    Ballone, P.; Jones, R. O.

    2002-10-01

    Ring-opening polymerization of cyclic polycarbonate oligomers, where monofunctional active sites act on difunctional monomers to produce an equilibrium distribution of rings and chains, leads to a "living polymer." Monte Carlo simulations [two-dimensional (2D) and three-dimensional (3D)] of the effects of single [J. Chem. Phys. 115, 3895 (2001)] and multiple active sites [J. Chem. Phys. 116, 7724 (2002)] are extended here to trifunctional active sites that lead to branching. Low concentrations of trifunctional particles c3 reduce the degree of polymerization significantly in 2D, and higher concentrations (up to 32%) lead to further large changes in the phase diagram. Gel formation is observed at high total density and sizable c3 as a continuous transition similar to percolation. Polymer and gel are much more stable in 3D than in 2D, and both the total density and the value of c3 required to produce high molecular weight aggregates are reduced significantly. The degree of polymerization in high-density 3D systems is increased by the addition of trifunctional monomers and reduced slightly at low densities and low c3. The presence of branching makes equilibrium states more sensitive (in 2D and 3D) to changes in temperature T. The stabilities of polymer and gel are enhanced by increasing T, and—for sufficiently high values of c3—there is a reversible polymer-gel transformation at a density-dependent floor temperature.

  10. p/n-Polarity of thiophene oligomers in photovoltaic cells: role of molecular vs. supramolecular properties.

    Science.gov (United States)

    Ghosh, Tanwistha; Gopal, Anesh; Saeki, Akinori; Seki, Shu; Nair, Vijayakumar C

    2015-04-28

    Molecular and supramolecular properties play key roles in the optoelectronic properties and photovoltaic performances of organic materials. In the present work, we show how small changes in the molecular structure affect such properties, which in turn control the intrinsic and fundamental properties such as the p/n-polarity of organic semiconductors in bulk-heterojunction solar cells. Herein, we designed and synthesized two acceptor-donor-acceptor type semiconducting thiophene oligomers end-functionalized with oxazolone/isoxazolone derivatives (OT1 and OT2 respectively). The HOMO-LUMO energy levels of both derivatives were found to be positioned in such a way that they can act as electron acceptors to P3HT and electron donors to PCBM. However, OT1 functions as a donor (with PCBM) and OT2 as an acceptor (with P3HT) in BHJ photovoltaic cells, and their reverse roles results in either no or poor performance of the cells. Detailed studies using UV-vis absorption and fluorescence spectroscopy, time-correlated single photon counting, UV-photoelectron spectroscopy, density functional theory calculations, X-ray diffraction, and thermal gravimetric analysis proved that both molecular and supramolecular properties contributed equally but in a contrasting manner to the abovementioned observation. The obtained results were further validated by flash-photolysis time-resolved microwave conductivity studies which showed an excellent correlation between the structure, property, and device performances of the materials.

  11. Hydrogen bonding as the origin of the switching behavior in dithiolated phenylene-vinylene oligomers

    KAUST Repository

    Obodo, Tobechukwu Joshua

    2013-08-29

    We investigate theoretically the switching behavior of a dithiolated phenylene-vinylene oligomer sandwiched between Au(111) electrodes using self-interaction corrected density-functional theory combined with the nonequilibrium Green\\'s-function method for quantum transport. The molecule presents a configurational bistability, which can be exploited in constructing molecular memories, switches, and sensors. We find that protonation of the terminating thiol groups is at the origin of the change in conductance. H bonding at the thiol group weakens the S-Au bond and reduces by about one order of magnitude the transmission coefficient at the Fermi level, and thus the linear response conductance. Furthermore, protonation downshifts in energy the position of the highest occupied molecular orbital, so that the current of the protonated species is lower than that of the unprotonated one along the entire bias range investigated, from −1.5 to 1.5 V. A second protonation at the opposite thiol group has only minor effects and no further drastic reduction in transmission takes place. Our results allow us to re-interpret the experimental data originally attributing the conductance reduction to H dissociation.

  12. White organic light-emitting diodes based on electroplex from polyvinyl carbazole and carbazole oligomers blends

    International Nuclear Information System (INIS)

    Fei-Peng, Chen; Bin, Xu; Wen-Jing, Tian; Zu-Jin, Zhao; Ping, Lü; Chan, Im

    2010-01-01

    White organic light-emitting diodes with a blue emitting material fluorene-centred ethylene-liked carbazole oligomer (Cz6F) doped into polyvinyl carbazole (PVK) as the single light-emitting layer are reported. The optical properties of Cz6F, PVK, and PVK:Cz6F blends are studied. Single and double layer devices are fabricated by using PVK: Cz6F blends, and the device with the configuration of indium tin oxide (ITO)/PVK:Cz6F/tris(8-hydroxyquinolinate)aluminium (Alq 3 )/LiF/A1 exhibits white light emission with Commission Internationale de l'Éclairage chromaticity coordinates of (0.30, 0.33) and a brightness of 402 cd/m 2 . The investigation reveals that the white light is composed of a blue–green emission originating from the excimer of Cz6F molecules and a red emission from an electroplex from the PVK:Cz6F blend films

  13. White organic light-emitting diodes based on electroplex from polyvinyl carbazole and carbazole oligomers blends

    Science.gov (United States)

    Chen, Fei-Peng; Xu, Bin; Zhao, Zu-Jin; Tian, Wen-Jing; Lü, Ping; Im, Chan

    2010-03-01

    White organic light-emitting diodes with a blue emitting material fluorene-centred ethylene-liked carbazole oligomer (Cz6F) doped into polyvinyl carbazole (PVK) as the single light-emitting layer are reported. The optical properties of Cz6F, PVK, and PVK:Cz6F blends are studied. Single and double layer devices are fabricated by using PVK: Cz6F blends, and the device with the configuration of indium tin oxide (ITO)/PVK:Cz6F/tris(8-hydroxyquinolinate)aluminium (Alq3)/LiF/A1 exhibits white light emission with Commission Internationale de l'Éclairage chromaticity coordinates of (0.30, 0.33) and a brightness of 402 cd/m2. The investigation reveals that the white light is composed of a blue-green emission originating from the excimer of Cz6F molecules and a red emission from an electroplex from the PVK:Cz6F blend films.

  14. Exciton and biexciton signatures in femtosecond transient absorption of π-conjugated oligomers

    Science.gov (United States)

    Klimov, Victor I.; McBranch, Duncan W.; Barashkov, Nikolay N.; Ferraris, John P.

    1997-12-01

    We report femtosecond transient-absorption studies of a five-ring oligomer of polyphenylenevinylene prepared in two different forms: as solid-state films and dilute solutions. Both types of samples exhibit a photoinduced absorption (PA) band with dynamics which closely match those of the stimulated emission (SE), demonstrating unambiguously that these features originate from the same species, namely from intrachain singlet excitons. Photochemical degradation of the solid-state samples is demonstrated to dramatically shorten the SE dynamics above a moderate incident pump fluence, whereupon the dynamics of the SE and the long- wavelength PA no longer coincide. In contrast to solutions, solid-state films exhibit an additional short-wavelength PA band with pump-independent dynamics, indicating the efficient formation of non-emissive inter-chain excitons. Correlations in the subpicosecond dynamics of the two PA features, as well as the pump intensity-dependence provide strong evidence that the formation of inter-chain excitons is mediated by intrachain two-exciton states. At high pump levels, we see a clear indication of interaction between excited states also in dilute solutions. This is manifested as a superlinear pump-dependence and shortening of the decay dynamics of the SE. We attribute this behavior to the formation of biexcitons resulting from coherent interaction between two excitons on a single chain.

  15. Exciton and biexciton signatures in femotosecond transient absorption of {pi}-conjugated oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Klimov, V.; McBranch, D. [Los Alamos National Lab., NM (United States); Barashkov, N.; Ferraris, J. [Univ. of Texas, Dallas, TX (United States)

    1997-10-01

    The authors report femotosecond transient-absorption studies of a five-ring oligomer of polyphenylenevinylene (PPV) prepared in two different forms: as solid-state films and dilute solutions. Both types of samples exhibit a photoinduced absorption (PA) band with dynamics which closely match those of the stimulated emission (SE), demonstrating unambiguously that these features originate from the same species, namely from intrachain singlet excitons. Photo-chemical degradation of the solid-state samples is demonstrated to dramatically shorten the SE dynamics above a moderate incident pump fluence, whereupon the dynamics of the SE and the long-wavelength PA no longer coincide. In contrast to solutions, solid-state films exhibit an additional short-wavelength PA band with pump-independent dynamics, indicating the efficient formation of non-emissive inter-chain excitons. Correlations in the subpicosecond dynamics of the two PA features, as well as the pump intensity-dependence provide strong evidence that the formation of inter-chain excitons is mediated by intrachain two-exciton states. At high pump levels, the authors see a clear indication of interaction between excited states also in dilute solutions. This is manifested as a superlinear pump-dependence and shortening of the decay dynamics of the SE. They attribute this behavior to the formation of biexcitons resulting from coherent interaction between two excitons on a single chain.

  16. Global styrene oligomers monitoring as new chemical contamination from polystyrene plastic marine pollution.

    Science.gov (United States)

    Kwon, Bum Gun; Koizumi, Koshiro; Chung, Seon-Yong; Kodera, Yoichi; Kim, Jong-Oh; Saido, Katsuhiko

    2015-12-30

    Polystyrene (PS) plastic marine pollution is an environmental concern. However, a reliable and objective assessment of the scope of this problem, which can lead to persistent organic contaminants, has yet to be performed. Here, we show that anthropogenic styrene oligomers (SOs), a possible indicator of PS pollution in the ocean, are found globally at concentrations that are higher than those expected based on the stability of PS. SOs appear to persist to varying degrees in the seawater and sand samples collected from beaches around the world. The most persistent forms are styrene monomer, styrene dimer, and styrene trimer. Sand samples from beaches, which are commonly recreation sites, are particularly polluted with these high SOs concentrations. This finding is of interest from both scientific and public perspectives because SOs may pose potential long-term risks to the environment in combination with other endocrine disrupting chemicals. From SOs monitoring results, this study proposes a flow diagram for SOs leaching from PS cycle. Using this flow diagram, we conclude that SOs are global contaminants in sandy beaches around the world due to their broad spatial distribution. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. A hydrogel biosensor for high selective and sensitive detection of amyloid-beta oligomers.

    Science.gov (United States)

    Sun, Liping; Zhong, Yong; Gui, Jie; Wang, Xianwu; Zhuang, Xiaorong; Weng, Jian

    2018-01-01

    Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive cognitive and memory impairment. It is the most common neurological disease that causes dementia. Soluble amyloid-beta oligomers (AβO) in blood or cerebrospinal fluid (CSF) are the pathogenic biomarker correlated with AD. A simple electrochemical biosensor using graphene oxide/gold nanoparticles (GNPs) hydrogel electrode was developed in this study. Thiolated cellular prion protein (PrP C ) peptide probe was immobilized on GNPs of the hydrogel electrode to construct an AβO biosensor. Electrochemical impedance spectroscopy was utilized for AβO analysis. The specific binding between AβO and PrP C probes on the hydrogel electrode resulted in an increase in the electron-transfer resistance. The biosensor showed high specificity and sensitivity for AβO detection. It could selectively differentiate AβO from amyloid-beta (Aβ) monomers or fibrils. Meanwhile, it was highly sensitive to detect as low as 0.1 pM AβO in artificial CSF or blood plasma. The linear range for AβO detection is from 0.1 pM to 10 nM. This biosensor could be used as a cost-effective tool for early diagnosis of AD due to its high electrochemical performance and bionic structure.

  18. Hamster female protein, a pentameric oligomer capable of reassociation and hybrid formation

    International Nuclear Information System (INIS)

    Coe, J.E.; Ross, M.J.

    1987-01-01

    Syrian hamster female protein (SFP), a serum oligomer composed of five identical subunits, was reassociated in vitro monomer subunits. The reconstituted pentamer was genuine by morphologic, antigenic, and structural criteria. Another female protein (FP), a homologue from Armenian hamsters (AFP), also reassociated into a pentamer after dissociation with 5 M guanidine hydrochloride. These two FP's hybridized when a mixture of them was dissociated and then reassociated. Differences between the parent FP's were used to show that the recombinant pentamer contained monomer subunits from both SFP and AFP. Reassociation of both FP's was enhanced by increasing FP concentration and also by adding Ca 2+ during reassembly. The two FP's differed in their reassociation profile in that SFP was especially efficient in reassembly, whereas AFP was more dependent upon Ca 2+ . Female protein is a homologue of C-reactive protein and amyloid P component, and all of these proteins (pentraxins) share a similar structure. The in vitro dissociation-reassociation of female protein described herein may reflect an in vivo dissociation-reassociation which is functionally important and a common metabolic feature within this family of proteins

  19. Alzheimer-associated Aβ oligomers impact the central nervous system to induce peripheral metabolic deregulation

    Science.gov (United States)

    Clarke, Julia R; Lyra e Silva, Natalia M; Figueiredo, Claudia P; Frozza, Rudimar L; Ledo, Jose H; Beckman, Danielle; Katashima, Carlos K; Razolli, Daniela; Carvalho, Bruno M; Frazão, Renata; Silveira, Marina A; Ribeiro, Felipe C; Bomfim, Theresa R; Neves, Fernanda S; Klein, William L; Medeiros, Rodrigo; LaFerla, Frank M; Carvalheira, Jose B; Saad, Mario J; Munoz, Douglas P; Velloso, Licio A; Ferreira, Sergio T; De Felice, Fernanda G

    2015-01-01

    Alzheimer's disease (AD) is associated with peripheral metabolic disorders. Clinical/epidemiological data indicate increased risk of diabetes in AD patients. Here, we show that intracerebroventricular infusion of AD-associated Aβ oligomers (AβOs) in mice triggered peripheral glucose intolerance, a phenomenon further verified in two transgenic mouse models of AD. Systemically injected AβOs failed to induce glucose intolerance, suggesting AβOs target brain regions involved in peripheral metabolic control. Accordingly, we show that AβOs affected hypothalamic neurons in culture, inducing eukaryotic translation initiation factor 2α phosphorylation (eIF2α-P). AβOs further induced eIF2α-P and activated pro-inflammatory IKKβ/NF-κB signaling in the hypothalamus of mice and macaques. AβOs failed to trigger peripheral glucose intolerance in tumor necrosis factor-α (TNF-α) receptor 1 knockout mice. Pharmacological inhibition of brain inflammation and endoplasmic reticulum stress prevented glucose intolerance in mice, indicating that AβOs act via a central route to affect peripheral glucose homeostasis. While the hypothalamus has been largely ignored in the AD field, our findings indicate that AβOs affect this brain region and reveal novel shared molecular mechanisms between hypothalamic dysfunction in metabolic disorders and AD. PMID:25617315

  20. Effects of Lytic Polysaccharide Monooxygenase Oxidation on Cellulose Structure and Binding of Oxidized Cellulose Oligomers to Cellulases

    Energy Technology Data Exchange (ETDEWEB)

    Vermaas, Josh V.; Crowley, Michael F.; Beckham, Gregg T.; Payne, Christina M.

    2015-05-21

    with different affinities relative to cellobiose itself, which potentially affects hydrolytic turnover through product inhibition. To examine the effect of oxidation on cello-oligomer binding, we use thermodynamic integration to compute the relative change in binding free energy between the hydrolyzed and oxidized products in the active site of Family 7 and Family 6 processive glycoside hydrolases, Trichoderma reesei Cel7A and Cel6A, which are key industrial cellulases and commonly used model systems for fungal cellulases. Our results suggest that the equilibrium between the two reducing end oxidized products, favoring the linear aldonic acid, may increase product inhibition, which would in turn reduce processive substrate turnover. In the case of LMPO action at the nonreducing end, oxidation appears to lower affinity with the nonreducing end specific cellulase, reducing product inhibition and potentially promoting processive cellulose turnover. Overall, this suggests that oxidation of recalcitrant polysaccharides by LPMOs accelerates degradation not only by increasing the concentration of chain termini but also by reducing decrystallization work, and that product inhibition may be somewhat reduced as a result.

  1. A spectroelectrochemical and chemical study on oxidation of hydroxycinnamic acids in aprotic medium

    Energy Technology Data Exchange (ETDEWEB)

    Petrucci, Rita [Dipartimento di Ingegneria Chimica M.M.P.M., Universita di Roma ' La Sapienza' , via del Castro Laurenziano 7, I-00161 Rome (Italy)]. E-mail: rita.petrucci@uniroma1.it; Astolfi, Paola [Dipartimento di Scienze dei Materiali e della Terra, Universita Politecnica delle Marche, via Brecce Bianche, I-60131 Ancona (Italy); Greci, Lucedio [Dipartimento di Scienze dei Materiali e della Terra, Universita Politecnica delle Marche, via Brecce Bianche, I-60131 Ancona (Italy); Firuzi, Omidreza [Dipartimento di Farmacologia delle Sostanze Naturali e Fisiologia Generale, Universita di Roma ' La Sapienza' , p.le Aldo Moro 5, I-00185 Rome (Italy); Saso, Luciano [Dipartimento di Farmacologia delle Sostanze Naturali e Fisiologia Generale, Universita di Roma ' La Sapienza' , p.le Aldo Moro 5, I-00185 Rome (Italy); Marrosu, Giancarlo [Dipartimento di Ingegneria Chimica M.M.P.M., Universita di Roma ' La Sapienza' , via del Castro Laurenziano 7, I-00161 Rome (Italy)

    2007-02-01

    Electrochemical and chemical oxidation of hydroxycinnamic acids (HCAs) was studied to investigate the mechanisms occurring in their antioxidant activities in a protons poor medium. Electrolyses and chemical reactions were followed on-line by monitoring the UV-spectral changes with time; final solutions were analysed by HPLC-MS. Anodic oxidation of mono- and di-HCAs, studied by cyclic voltammetry and controlled potential electrolyses, occurs via a reversible one-step two-electrons process, yielding the corresponding stable phenoxonium cation. A cyclization product was also proposed, as supported by ESR studies. Chemical oxidation with lead dioxide leads to different oxidation products according to the starting substrate. Di-HCAs like chlorogenic and rosmarinic acids and the ethyl ester of caffeic acid gave the corresponding neutral o-quinones, while mono-HCAs like cumaric, ferulic and sinapinic acids yielded the corresponding unstable neutral phenoxyl radical, as supported by the formation of dimerization products evidenced by HPLC-MS. In the case of caffeic acid, traces of the dimerization product suggest that the neutral phenoxyl radical may competitively undergo dimerization or decomposition of the neutral quinone. Chemical oxidation of HCAs was also followed by ESR spectroscopy: the di-HCAs radical anions were generated and detected, whereas among the mono-HCAs only the phenoxyl radical of the sinapinic acid was recorded.

  2. Ruminal Methane Production on Simple Phenolic Acids Addition in in Vitro Gas Production Method

    Directory of Open Access Journals (Sweden)

    A. Jayanegara

    2009-04-01

    Full Text Available Methane production from ruminants contributes to total global methane production, which is an important contributor to global warming. In this experiment, six sources of simple phenolic acids (benzoic, cinnamic, phenylacetic, caffeic, p-coumaric and ferulic acids at two different levels (2 and 5 mM added to hay diet were evaluated for their potential to reduce enteric methane production using in vitro Hohenheim gas production method. The measured variables were gas production, methane, organic matter digestibility (OMD, and short chain fatty acids (SCFA. The results showed that addition of cinnamic, caffeic, p-coumaric and ferulic acids at 5 mM significantly (P p-coumaric > ferulic > cinnamic. The addition of simple phenols did not significantly decrease OMD. Addition of simple phenols tends to decrease total SCFA production. It was concluded that methane decrease by addition of phenolic acids was relatively small, and the effect of phenolic acids on methane decrease depended on the source and concentration applied.

  3. Rheological and mechanical properties and interfacial stress development of composite cements modified with thio-urethane oligomers.

    Science.gov (United States)

    Bacchi, Ataís; Pfeifer, Carmem S

    2016-08-01

    Thio-urethane oligomers have been shown to reduce stress and increase toughness in highly filled composite materials. This study evaluated the influence of thio-urethane backbone structure on rheological and mechanical properties of resin cements modified with a fixed concentration of the oligomers. Thio-urethane oligomers (TU) were synthesized by combining thiols - pentaerythritol tetra-3-mercaptopropionate (PETMP) or trimethylol-tris-3-mercaptopropionate (TMP) - with isocyanates - 1,6-hexanediol-diissocyante (HDDI) (aliphatic) or 1,3-bis(1-isocyanato-1-methylethyl)benzene (BDI) (aromatic) or dicyclohexylmethane 4,4'-diisocyanate (HMDI) (cyclic), at 1:2 isocyanate:thiol, leaving pendant thiols. 20wt% TU were added to BisGMA-UDMA-TEGDMA (5:3:2). 60wt% silanated inorganic fillers were added. Near-IR was used to follow methacrylate conversion and rate of polymerization ( [Formula: see text] ). Mechanical properties were evaluated in three-point bending (ISO 4049) for flexural strength/modulus (FS/FM, and toughness), and notched specimens (ASTM Standard E399-90) for fracture toughness (KIC). PS was measured on the Bioman. Viscosity (V) and gel-points (defined as the crossover between storage and loss shear moduli (G'/G″)) were obtained with rheometry. Glass transition temperature (Tg), cross-link density and homogeneity of the network were obtained with dynamic mechanical analysis. Film-thickness was evaluated according to ISO 4049. DC and mechanical properties increased and [Formula: see text] and PS decreased with the addition of TUs. Gelation (G'/G″) was delayed and DC at G'/G″ increased in TU groups. Tg and cross-link density dropped in TU groups, while oligomers let to more homogenous networks. An increase in V was observed, with no effect on film-thickness. Significant reductions in PS were achieved at the same time conversion and mechanical properties increased. The addition of thio-urethane oligomers proved successful in improving several key properties

  4. Interaction of humic acids and humic-acid-like polymers with herpes simplex virus type 1

    Science.gov (United States)

    Klöcking, Renate; Helbig, Björn

    The study was performed in order to compare the antiviral activity against herpes simplex virus type 1 (HSV-1) of synthetic humic-acid-like polymers to that of their low-molecular-weight basic compounds and naturally occurring humic acids (HA) in vitro. HA from peat water showed a moderate antiviral activity at a minimum effective concentration (MEC) of 20 µg/ml. HA-like polymers, i.e. the oxidation products of caffeic acid (KOP), hydrocaffeic acid (HYKOP), chlorogenic acid (CHOP), 3,4-dihydroxyphenylacetic acid (3,4-DHPOP), nordihydroguaretic acid (NOROP), gentisinic acid (GENOP), pyrogallol (PYROP) and gallic acid (GALOP), generally inhibit virus multiplication, although with different potency and selectivity. Of the substances tested, GENOP, KOP, 3,4-DHPOP and HYKOP with MEC values in the range of 2 to 10 µg/ml, proved to be the most potent HSV-1 inhibitors. Despite its lower antiviral potency (MEC 40 µg/ml), CHOP has a remarkable selectivity due to the high concentration of this polymer that is tolerated by the host cells (>640 µg/ml). As a rule, the antiviral activity of the synthetic compounds was restricted to the polymers and was not preformed in the low-molecular-weight basic compounds. This finding speaks in favour of the formation of antivirally active structures during the oxidative polymerization of phenolic compounds and, indirectly, of corresponding structural parts in different HA-type substances.

  5. Horseradish peroxidase-catalyzed oligomerization of ferulic acid on a template of a tyrosine-containing tripeptide

    NARCIS (Netherlands)

    Oudgenoeg, G.; Dirksen, E.; Ingemann, S.; Hilhorst, R.; Gruppen, H.; Boeriu, C.G.; Piersma, S.R.; Berkel, W.J.H. van; Laane, C.; Voragen, A.G.J.

    2002-01-01

    Ferulic acid (FA) is an abundantly present phenolic constituent of plant cell walls. Kinetically controlled incubation of FA and the tripeptide Gly-Tyr-Gly (GYG) with horseradish peroxidase and H2O2 yielded a range of new cross-linked products. Two predominant series of hetero-oligomers of FA linked

  6. Subnanomolar antisense activity of phosphonate-peptide nucleic acid (PNA) conjugates delivered by cationic lipids to HeLa cells

    DEFF Research Database (Denmark)

    Shiraishi, Takehiko; Hamzavi, Ramin; Nielsen, Peter E

    2008-01-01

    oligomer. This modification of the PNA does not interfere with the nucleic acid target binding affinity based on thermal stability of the PNA/RNA duplexes. When delivered to cultured HeLa pLuc705 cells by Lipofectamine, the PNAs showed dose-dependent nuclear antisense activity in the nanomolar range...

  7. Theoretical study on the cage-like nanostructures formed by amino acids and their potential applications as drug carriers

    Science.gov (United States)

    Weng, Pei Pei; Fan, Jian Fen; Lin, Hui Fang; Zhao, Xin; Si, Xia Lan

    2017-12-01

    The cage-like octamer, decamer and dodecamer constructed from aspartic acid monomers have been studied to explore their potential applications as drug carriers using the density functional theory. The calculation results indicate that these stable cage-like oligomers are mainly connected by the -C=O…HOOC- and -HN…HOOC- H-bonds and still keep stability and good drum-shaped topologies after the incorporation of 5-fluorouracil, paraldehyde and C24, respectively. The self-assembled cage-like oligomers may be applied to the preparation of new biological materials and the design of drug delivery systems.

  8. Crystallisation and structural studies of monodisperse nylon oligomers and related polymers

    International Nuclear Information System (INIS)

    Sikorski, P.T.

    2001-11-01

    Using electron and X-ray diffraction data, together with computerised molecular modeling, the structures of monodisperse nylon oligomers and related polymers have been investigated. Structural changes on heating were also studied. The molecules were crystallised from solution and their morphologies examined using optical and transmission electron microscopy. Lath-like lamellar crystals of the polyester poly-β-propiolactone were crystallised isothermally. The interpretation of the diffraction data with the use of molecular modeling led to the discovery of the new crystalline structure, the γ-structure. In the γ-structure, the polyester chain is in an all-trans conformation and the structure consists of a two-chain, basal-faced, orthorhombic unit cell. The setting angles, with respect to the a axis, are ± 51.5 deg for the corner and centre chains, respectively. The lamellae are 5 nm in thickness and the chains run orthogonal to the lamellar surface. The general fold direction is along the a-axis (long axis of the crystal) and the chain folds successively in the [110] and [11-bar0] directions. Three different nylon 4 6 oligomers were crystallised from solution using a range of crystallisation methods. The 4- and 8-amide molecules were found to form three-dimensional crystals, in which the crystal thickness was much greater than the molecular length. The structure was found to be different from the nylon 4 6 polymer reported previously. It was found that the type of hydrogen-bonded sheet formed by these molecules can influence the way in which these sheets stack to form crystals. In addition, a study of the 9-amide molecule showed that a particular type of hydrogen-bonded sheet, a-sheet, is preferred for nylon 4 6. This discovery suggests that an amide unit is found in the fold in the chain-folded nylon 4 6 polymer crystals, to allow the a-sheets to be formed. It is not a consequence of a need to form a stress-free fold. In the regular adjacent re-entry chain

  9. Shrinkage / stress reduction and mechanical properties improvement in restorative composites formulated with thio-urethane oligomers.

    Science.gov (United States)

    Bacchi, Atais; Yih, Jonathan A; Platta, Jacqueline; Knight, Joseph; Pfeifer, Carmem S

    2018-02-01

    Thio-urethane oligomers (TUs) have been shown to favorably modify methacrylate networks to reduce stress and significantly increase fracture toughness. Since those are very desirable features in dental applications, the objective of this work was to characterize restorative composites formulated with the addition of TUs. TUs were synthesized by combining thiols - pentaerythritol tetra-3-mercaptopropionate (PETMP) or trimethylol-tris-3-mercaptopropionate (TMP) - with isocyanates - 1,6-Hexanediol-diissocyante (HDDI) (aliphatic) or 1,3-bis(1-isocyanato-1-methylethyl)benzene (BDI) (aromatic) or dicyclohexylmethane 4,4'-Diisocyanate (HMDI) (cyclic), at 1:2 isocyanate:thiol, leaving pendant thiols. 20wt% TU were added to BisGMA-TEGDMA (70-30%). To this organic matrix, 70wt% silanated inorganic fillers were added. Near-IR was used to follow methacrylate conversion and rate of polymerization (Rp max ). Mechanical properties were evaluated in three-point bending (ISO 4049) for flexural strength/modulus (FS/FM) and toughness (T), and notched specimens (ASTM Standard E399-90) for fracture toughness (K IC ). Polymerization stress (PS) was measured on the Bioman. Volumetric shrinkage (VS) was measured with the bonded disk technique. Glass transition temperature (Tg) and heterogeneity of network were obtained with dynamic mechanical analysis. The addition of TUs led to an increase in mechanical properties (except for Tg and FS). Fracture toughness ranged from 1.6-1.94MPam 1/2 for TU-modified groups, an increase of 33-61% in relation to the control (1.21 ± 0.1MPam 1/2 ). Toughness showed a two-fold increase in relation to the control: from 0.91MPa to values ranging from 1.70-1.95MPa. Flexural modulus was statistically higher for the TU-modified groups. The Tg, as expected, decreased for all TU groups due to the greater flexibility imparted to the network (which also explains the increase in toughness and fracture toughness). Narrower tan-delta peaks suggest more homogeneous

  10. Metabolism of Fructophilic Lactic Acid Bacteria Isolated from the Apis mellifera L. Bee Gut: Phenolic Acids as External Electron Acceptors

    Science.gov (United States)

    Filannino, Pasquale; Addante, Rocco; Pontonio, Erica; Gobbetti, Marco

    2016-01-01

    ABSTRACT Fructophilic lactic acid bacteria (FLAB) are strongly associated with the gastrointestinal tracts (GITs) of Apis mellifera L. worker bees due to the consumption of fructose as a major carbohydrate. Seventy-seven presumptive lactic acid bacteria (LAB) were isolated from GITs of healthy A. mellifera L. adults, which were collected from 5 different geographical locations of the Apulia region of Italy. Almost all of the isolates showed fructophilic tendencies: these isolates were identified as Lactobacillus kunkeei (69%) or Fructobacillus fructosus (31%). A high-throughput phenotypic microarray targeting 190 carbon sources was used to determine that 83 compounds were differentially consumed. Phenotyping grouped the strains into two clusters, reflecting growth performance. The utilization of phenolic acids, such as p-coumaric, caffeic, syringic, or gallic acids, as electron acceptors was investigated in fructose-based medium. Almost all FLAB strains showed tolerance to high phenolic acid concentrations. p-Coumaric acid and caffeic acid were consumed by all FLAB strains through reductases or decarboxylases. Syringic and gallic acids were partially metabolized. The data collected suggest that FLAB require external electron acceptors to regenerate NADH. The use of phenolic acids as external electron acceptors by the 4 FLAB showing the highest phenolic acid reductase activity was investigated in glucose-based medium supplemented with p-coumaric acid. Metabolic responses observed through a phenotypic microarray suggested that FLAB may use p-coumaric acid as an external electron acceptor, enhancing glucose dissimilation but less efficiently than other external acceptors such as fructose or pyruvic acid. IMPORTANCE Fructophilic lactic acid bacteria (FLAB) remain to be fully explored. This study intends to link unique biochemical features of FLAB with their habitat. The quite unique FLAB phenome within the group lactic acid bacteria (LAB) may have practical relevance

  11. Atorvastatin prevents Aβ oligomer-induced neurotoxicity in cultured rat hippocampal neurons by inhibiting Tau cleavage

    Science.gov (United States)

    Sui, Hai-juan; Zhang, Ling-ling; Liu, Zhou; Jin, Ying

    2015-01-01

    Aim: The proteolytic cleavage of Tau is involved in Aβ-induced neuronal dysfunction and cell death. In this study, we investigated whether atorvastatin could prevent Tau cleavage and hence prevent Aβ1–42 oligomer (AβO)-induced neurotoxicity in cultured cortical neurons. Methods: Cultured rat hippocampal neurons were incubated in the presence of AβOs (1.25 μmol/L) with or without atorvastatin pretreatment. ATP content and LDH in the culture medium were measured to assess the neuronal viability. Caspase-3/7 and calpain protease activities were detected. The levels of phospho-Akt, phospho-Erk1/2, phospho-GSK3β, p35 and Tau proteins were measured using Western blotting. Results: Treatment of the neurons with AβO significantly decreased the neuronal viability, induced rapid activation of calpain and caspase-3/7 proteases, accompanied by Tau degradation and relatively stable fragments generated in the neurons. AβO also suppressed Akt and Erk1/2 kinase activity, while increased GSK3β and Cdk5 activity in the neurons. Pretreatment with atorvastatin (0.5, 1, 2.5 μmol/L) dose-dependently inhibited AβO-induced activation of calpain and caspase-3/7 proteases, and effectively diminished the generation of Tau fragments, attenuated synaptic damage and increased neuronal survival. Atorvastatin pretreatment also prevented AβO-induced decreases in Akt and Erk1/2 kinase activity and the increases in GSK3β and Cdk5 kinase activity. Conclusion: Atorvastatin prevents AβO-induced neurotoxicity in cultured rat hippocampal neurons by inhibiting calpain- and caspase-mediated Tau cleavage. PMID:25891085

  12. Dynamics of the central phenylene ring torsional motion in halogenated phenylene ethynylene oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Pejov, Ljupco [Institute of Chemistry, Department of Physical Chemistry, SS. Cyril and Methodius University, Arhimedova 5, P.O. Box 162, 1000 Skopje(Macedonia, The Former Yugoslav Republic of)], E-mail: ljupcop@iunona.pmf.ukim.edu.mk; La Rosa, Manuela [PST Group- M6, STMicroelectronics, Stradale Primosole 50, 95121 Catania (Italy); Kocarev, Ljupco [Institute for Nonlinear Science, University of California, San Diego 9500 Gilman, Drive, La Jolla, CA 92093-0402 (United States); Macedonian Academy of Sciences and Arts, bul. Krste Misirkov 2, P.O. Box 428, 1000 Skopje (Macedonia, The Former Yugoslav Republic of)

    2007-11-09

    The dynamics of intramolecular torsional motion of central phenylene ring in a series of phenylene ethynylene oligomer derivatives was investigated. On the basis of calculated hindered rotational potentials corresponding to this motion, the torsional energy levels were obtained by solving the torsional Schroedinger equation. Subsequently, the torsional correlation time and transition probability was computed within the Bloembergen-Purcell-Pound (BPP) formalism, considering both the classical and quantum mechanical tunneling contributions to the intramolecular rotation. The results were interpreted in the context of molecular conductivity switching behavior of the considered series of compounds. Also some other parameters relevant to molecular admittance were calculated, such as the HOMO-LUMO energy difference and the spatial extent of the frontier molecular orbitals. Classical electrostatic arguments were applied to understand the physical basis of the conformational stability differences in the studied compounds. It was found that halogenation of the central phenylene ring may be used for fine-tuning of molecular conduction behavior, in the sense of modulating the HOMO-LUMO energy difference, the spatial extent of frontier MOs, as well as the barrier height to torsional motion of the central phenylene ring. The time scale of the temperature induced stochastic conformational switching between the 'on' and 'off' states, along with the corresponding transition probability could be varied by an order of magnitude upon halogenation of the central phenylene ring. The tunneling contributions to the torsional correlation time were found to be of minor importance in this context, and this quantity may be quite correctly estimated with the classical BPP approach.

  13. Dynamics of the central phenylene ring torsional motion in halogenated phenylene ethynylene oligomers

    International Nuclear Information System (INIS)

    Pejov, Ljupco; La Rosa, Manuela; Kocarev, Ljupco

    2007-01-01

    The dynamics of intramolecular torsional motion of central phenylene ring in a series of phenylene ethynylene oligomer derivatives was investigated. On the basis of calculated hindered rotational potentials corresponding to this motion, the torsional energy levels were obtained by solving the torsional Schroedinger equation. Subsequently, the torsional correlation time and transition probability was computed within the Bloembergen-Purcell-Pound (BPP) formalism, considering both the classical and quantum mechanical tunneling contributions to the intramolecular rotation. The results were interpreted in the context of molecular conductivity switching behavior of the considered series of compounds. Also some other parameters relevant to molecular admittance were calculated, such as the HOMO-LUMO energy difference and the spatial extent of the frontier molecular orbitals. Classical electrostatic arguments were applied to understand the physical basis of the conformational stability differences in the studied compounds. It was found that halogenation of the central phenylene ring may be used for fine-tuning of molecular conduction behavior, in the sense of modulating the HOMO-LUMO energy difference, the spatial extent of frontier MOs, as well as the barrier height to torsional motion of the central phenylene ring. The time scale of the temperature induced stochastic conformational switching between the 'on' and 'off' states, along with the corresponding transition probability could be varied by an order of magnitude upon halogenation of the central phenylene ring. The tunneling contributions to the torsional correlation time were found to be of minor importance in this context, and this quantity may be quite correctly estimated with the classical BPP approach