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Sample records for acid abts radicals

  1. Antioxidant activity applying an improved ABTS radical cation decolorization assay.

    Science.gov (United States)

    Re, R; Pellegrini, N; Proteggente, A; Pannala, A; Yang, M; Rice-Evans, C

    1999-05-01

    A method for the screening of antioxidant activity is reported as a decolorization assay applicable to both lipophilic and hydrophilic antioxidants, including flavonoids, hydroxycinnamates, carotenoids, and plasma antioxidants. The pre-formed radical monocation of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS*+) is generated by oxidation of ABTS with potassium persulfate and is reduced in the presence of such hydrogen-donating antioxidants. The influences of both the concentration of antioxidant and duration of reaction on the inhibition of the radical cation absorption are taken into account when determining the antioxidant activity. This assay clearly improves the original TEAC assay (the ferryl myoglobin/ABTS assay) for the determination of antioxidant activity in a number of ways. First, the chemistry involves the direct generation of the ABTS radical monocation with no involvement of an intermediary radical. Second, it is a decolorization assay; thus the radical cation is pre-formed prior to addition of antioxidant test systems, rather than the generation of the radical taking place continually in the presence of the antioxidant. Hence the results obtained with the improved system may not always be directly comparable with those obtained using the original TEAC assay. Third, it is applicable to both aqueous and lipophilic systems. PMID:10381194

  2. KINETICS PROFILES IN THE REACTION OF ABTS DERIVED RADICALS WITH SIMPLE PHENOLS AND POLYPHENOLS

    Directory of Open Access Journals (Sweden)

    CAROLA HENRIQUEZ

    2004-03-01

    Full Text Available The kinetic profile associated to the reaction of phenols with 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS derived radicals is extremely dependent of the characteristics of the substrate. In particular, polyphenols present complex profiles that can be associated to successive reactions of different reactive centers present in the target molecule. Also, changes in the secondary reactions of the produced radicals can lead to a partial recovery of the ABTS radical concentration at intermediate reaction times, as observed employing 1,4-dihydroxybenzene. Although the kinetic profiles of monophenols are considerably simpler, the stoichiometry of the process is unexpected. For example, the data obtained imply that four radicals are consumed by each p-tertbutylphenol molecule introduced into the system. This large stoichiometric coefficient is not compatible with a simple, phenol promoted, back reduction of the ABTS radical. These results, as well as the overshoot observed employing 1,4-dihydroxybencene, cast doubts on the use of ABTS based methodologies to quantitatively measure the capacity of a given compound to trap free radicals or the amount of free radical scavengers present in complex mixtures

  3. KINETICS PROFILES IN THE REACTION OF ABTS DERIVED RADICALS WITH SIMPLE PHENOLS AND POLYPHENOLS

    Scientific Electronic Library Online (English)

    CAROLA, HENRIQUEZ; CAROLINA, ALIAGA; EDUARDO, LISSI.

    2004-03-01

    Full Text Available The kinetic profile associated to the reaction of phenols with 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) derived radicals is extremely dependent of the characteristics of the substrate. In particular, polyphenols present complex profiles that can be associated to successive react [...] ions of different reactive centers present in the target molecule. Also, changes in the secondary reactions of the produced radicals can lead to a partial recovery of the ABTS radical concentration at intermediate reaction times, as observed employing 1,4-dihydroxybenzene. Although the kinetic profiles of monophenols are considerably simpler, the stoichiometry of the process is unexpected. For example, the data obtained imply that four radicals are consumed by each p-tertbutylphenol molecule introduced into the system. This large stoichiometric coefficient is not compatible with a simple, phenol promoted, back reduction of the ABTS radical. These results, as well as the overshoot observed employing 1,4-dihydroxybencene, cast doubts on the use of ABTS based methodologies to quantitatively measure the capacity of a given compound to trap free radicals or the amount of free radical scavengers present in complex mixtures

  4. SCAVENGING ACTIVITY OF DICLOFENAC: INTERACTION WITH ABTS RADICAL CATION AND PEROXYL RADICALS

    Scientific Electronic Library Online (English)

    C, ROJO; M. J, ÁLVAREZ-FIGUEROA; M, SOTO; A, CAÑETE; D, PESSOA-MAHANA; C, LÓPEZ-ALARCÓN.

    Full Text Available The scavenging activity of diclofenac was estimated by its capability to bleach ABTS radical cation, and ORAC (oxygen radical absorbance capacity) methodology. In addition, GC-MS technique was used to establish if the lactamic derivative of diclofenac was formed as final product in the interaction w [...] ith peroxyl radicals. Diclofenac bleached ABTS radical cation in a concentration-dependent way. In ORAC assays, diclofenac inhibited the consumption of fluorescein and c-phycocyanin mediated by peroxyl radicals. An ORAC-fluorescein, and ORAC-c-phycocyanin value of 0.3, and 0.004 was estimated, respectively. From the downcurvature observed in Stern-Volmer-like plots, we postulated that the low protection of c-phycocyanin is related to secondary damage of c-phycocyanin by the secondary radical of diclofenac. By GC-MS studies only a 2,6-dichloroaniline derivative was detected as product afterthe reaction with peroxyl radicals.

  5. Alteration of fatty acids content during cow's and goat's milk fermentation with ABT-2 culture

    OpenAIRE

    Vedran Sla?anac; Jovica Hardi; Hrvoje Pavlovi?; Mato Vlaini?; Mirela Lu?an

    2005-01-01

    In this paper, changes in composition and contents of each fatty acid during fermentation with ABT-2 culture were examined. The objective of this study was to determinate the increase of short (SCFA) and medium (MCFA) chain fatty acids in goat's and cow's milk during fermentation with ABT-2 culture. The hypothesis of this study was that higher contents of SCFA and MCFA are produced in goat's milk in comparison with cow's milk, during fermentation with ABT-2 culture. Obtained results have show...

  6. EVALUATION OF THE EXTINCTION COEFFICIENT OF THE ABTS DERIVED RADICAL CATION

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    Carola Henriquez

    2002-12-01

    Full Text Available The exact knowledge of the value of the extinction coefficient of the ABTS derived radical is necessary for its quantitative use in the evaluation of the antioxidant capacity of pure compounds and/or complex mixtures. We have performed experiments in order to stablish its lower and upper limits of its value. The limits obtained, \t\t\t\t1.0 x 10(4 M-1 cm-1 Conocer el valor exacto del coeficiente de extinción del radical catión derivado del ABTS es un pre-requisito para su empleo en la evaluación de la capacidad antioxidante de compuestos puros polifuncionales o mezclas complejas. Nosotros hemos realizado emperimentos que permiten establecer límites inferiores y superiores para su valor. Los límites obtenidos \t\t\t1.0 x 10(4 M-1 cm-1 <= épsilon 734 <= 1.6 x 10(4 M-1 cm-1 son compatibles con los valores reportados en la literatura. Sin embargo, el uso de estos valores conduced a coeficientes estequiométricos anormalmente altos para sus reacciones con comuestos simples como monofenoles y triptofano.

  7. Methylseleninic acid potentiates multiple types of cancer cells to ABT-737-induced apoptosis by targeting Mcl-1 and Bad

    DEFF Research Database (Denmark)

    Yin, Shutao; Dong, Yinhui

    2012-01-01

    ABT-737, a novel small molecule inhibitor of Bcl-2 family proteins, holds great promise to complement current cancer therapies. However many types of solid cancer cells are resistant to ABT-737. One practical approach to improve its therapeutic efficacy is to combine with the agents that can overcome such resistance to restore the sensitivity. In the present study, a second-generation selenium compound methylseleninic acid (MSeA) synergistically sensitized MDA-MB-231 human breast cancer cells, HT-29 human colon cancer cells and DU145 human prostate cancer cells to apoptosis induction by ABT-737, as evidenced by greater than additive enhancement of Annexin V/FITC positive (apoptotic) cells and activation of multiple caspases and PARP cleavage. Mechanistic investigation demonstrated that MSeA significantly decreased basal Mcl-1 expression and ABT-737-induced Mcl-1 expression. Knocking down of Mcl-1 with RNAi approach supported the functional significance of this molecular target. More importantly, we identifiedinactivation of Bad by phosphorylation on ser-136 and ser-112 as a novel mechanism involved in ABT-737 resistance, which can be overcome by combining with MSeA. In addition, we found that expression of Bax was required for the efficient execution of synergistic sensitization. Our findings, for the first time, provide a strong mechanistic rationale for developing MSeA as a novel sensitizing agent of ABT-737.

  8. Antioxidant components of Viburnum opulus L. determined by on-line HPLC-UV-ABTS radical scavenging and LC-UV-ESI-MS methods.

    Science.gov (United States)

    Karaçelik, Ayça Akta?; Küçük, Murat; ?skefiyeli, Zeynep; Aydemir, Sezgin; De Smet, Seppe; Miserez, Bram; Sandra, Patrick

    2015-05-15

    Antioxidant activity of the juice and seed and skin extracts prepared with methanol, acetonitrile, and water of Viburnum opulus L. grown in Eastern Black Sea Region were studied with an on-line HPLC-ABTS method and off-line antioxidant methods, among which a linear positive correlation was observed. The fruit extracts were analysed with the HPLC-UV method optimised with 14 standard phenolics. Identification of the phenolic components in the juice was made using an HPLC-UV-ESI-MS method. Nineteen phenolic compounds in juice were identified by comparing the retention times and mass spectra with those of the standards and the phenolics reported in the literature. The major peaks in the juice belonged to coumaroyl-quinic acid, chlorogenic acid, procyanidin B2, and procyanidin trimer. Quite different antioxidant composition profiles were obtained from the extracts with the solvents of different polarities. The antioxidant activities of the seed extracts were higher than those of the skin extracts in general. PMID:25577058

  9. Amino Acid Content, Fatty Acid Profile and Radical Scavenging Capacities of Coccinia grandis (L. Voigt. Fruits

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    Ibtisam G. Doka

    2014-12-01

    Full Text Available In Sudan, the unripe (green fruits of Coccinia grandis (L. Voigt. (Cucurbitaceae are eaten raw as salads or cooked by either boiling or frying in oil. In this study the amino acid content, fatty acid profile and radical scavenging capacities of the raw and boiled fruits were determined. The total amino acids ranged from 7736 mg/100 g in raw fruits to 7766 mg/100 g in boiled fruits and with the exception of leucine, boiling did not cause significant difference in the essential amino acids content (32.5% of the fruits. Boiling caused significant (p<0.05 change in the amount of the total saturated (from 38.04% in raw fruits to 14.156% in boiled ones and unsaturated fatty acids (from 57.59% in raw fruits to 85.774% in boiled ones. Moreover, boiling caused significant (p<0.05 losses of vitamin C by 73% and polyphenols by 70.6 % contents. The high antioxidant activity of the raw fruits (IC50 22 mg/L, determined by DPPH and ABTS assays, was declined dramatically upon boiling. In conclusion, the results of this study suggested that fruits of C. grandis could have health beneficial effect and their consumption in the raw state is preferable.

  10. Thiazolidin-4-ones from 3-(Aminomethyl)pyridine, Arenealdehydes and Mercaptoacetic Acid: Synthesis and Radical Scavenger Activity

    Scientific Electronic Library Online (English)

    Adriana M., Neves; Auri R., Duval; Gabriele A., Berwaldt; Daniela P., Gouvêa; Natália P., Flores; Pâmela G. da, Silva; Francieli M., Stefanello; Wilson, Cunico.

    2015-02-01

    Full Text Available The efficient synthesis of fifteen novel thiazolidin-4-ones from reaction of 3-(aminomethyl) pyridine (3-picolylamine), arenealdenhydes and mercaptoacetic acid was described. The desired compounds were obtained in moderated to good yields by two methodologies: conventional heating and ultrasound irr [...] adiation. The thiazolidin-4-ones were fully identified and characterized by nuclear magnetic resonance (NMR), gas chromatography coupled to mass spectrometry (GC?MS) and high resolution mass spectrometry (HRMS) techniques. Four compounds showed radical scavenger activity in the 2,2’-azinobis-3-ethyl-benzothiazoline-6-sulfonic acid (ABTS) assay.

  11. Isoprene, sulphoxy radical-anions and acidity

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    K. J. Rudzi?ski

    2008-12-01

    Full Text Available Transformation of isoprene coupled with autoxidation of SIV in aqueous solutions was studied experimentally and by chemical-kinetic modelling over broad range of solution acidities (pH=3–9 to complement the research on aqueous-phase and heterogeneous transformation of isoprene reported recently by many laboratories. Isoprene significantly slowed down the autoxidation in acidic and basic solutions, and accelerated it slightly in neutral solutions. Simultaneously, production of sulphate ions and formation of solution acidity were significantly reduced. Formation of sulphite and sulphate derivatives of isoprene – sulphurous acid mono-(2-methyl-4-oxo-but-2-enyl ester (m/z=162.9, sulphurous acid mono-(4-hydroxy-2-methyl-but-2-enyl ester (m/z=164.9, sulphuric acid mono-(2-methyl-4-oxo-but-2-enyl ester (m/z=178.9, sulphuric acid mono-(4-hydroxy-2-methyl-but-2-enyl ester (m/z=180.9 – was indicated by mass spectroscopic analysis of post-reaction mixtures. The results of experiments were explained by changes in a subtle quantitative balance of three superimposed processes whose rates depended in different manner on the acidity of reacting solutions – the scavenging of sulphoxy radicals by isoprene, the formation of sulphoxy radicals during further reactions of isoprene radicals, and the autoxidation of SIV itself. A chemical mechanism based on this idea was explored numerically to show good agreement with experimental data. Interaction of isoprene with sulphur(IV species and oxygen can possibly result in formation of new organosulphate components of atmospheric aerosols and waters, and influence distribution of reactive sulphur and oxygen species in isoprene-emitting organisms exposed to SIV pollutants.

  12. Peroxyl radicals of nucleic acids and their components

    International Nuclear Information System (INIS)

    If free radicals add to the bases of nucleic acids or abstract a hydrogen atom from the sugar moiety, mainly carbon-centered radicals are formed. In the presence of oxygen such carbon-centered radicals are converted into the corresponding peroxyl radicals at nearly diffusion-controlled rates (k ? 2 x 109 M-1 s-1). Our knowledge of the free-radical chemistry of purines, especially in the presence of oxygen, is at present still very limited, so that this discussion must be restricted to pyrimidines and to the sugar moiety. This article attempts to make the reader familiar with some of the complexities of peroxy radical reactions and to give some examples of how such reactions are reflected in the degradation of the free components of nucleic acids, and to what extent such results may be extrapolated to the nucleic acids themselves. 30 refs., 1 tab

  13. Determination of protective properties of Bardejovske Kuple spa curative waters by rotational viscometry and ABTS assay

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    TOPOLSKA Dominika

    2014-02-01

    Full Text Available Mineral waters from Bardejovske Kupele spa are natural, strongly mineralized, with healing effects. They are classified as hydrocarbonic - containing chloride and sodium - carbonic, cold, hypotonic, with a relatively high boric acid content. Potential anti-oxidative effects of curative waters from Bardejovske Kupele were investigated against the hyaluronan (HA degradation. High-molar-mass HA was exposed to the action of ascorbate and cupric ions, which initiate free-radical chain degradation. Time-dependent changes of dynamic viscosity (h of the HA solutions were monitored by rotational viscometry. The radical scavenging capacity of curative waters was determined by the ABTS assay. Despite a significantly high content of transition metal ions, especially iron, remarkable protective effects of the two curative spa waters were found, namely Alzbeta and Klara. Even though “Alzbeta´s“ iron content was 3.5-fold higher than “Klara´s“, “Alzbeta“ was shown to have better protective properties against the HA degradation compared to “Klara“. Bolus addition of ferric ions to the reaction system instead of the natural iron-containing curative water caused a significant HA degradation. The ABTS decolorization assay revealed that the curative spa waters were proven as poorly effective scavengers of the ABTS·+ cation radical.

  14. El ABTS•+ agente oxidante de diversos compuestos químicos y su mecanismo de reciclado entre la lacasa y el sustrato / The ABTS•+ an oxidant agent of different chemical compounds and its recycling process between laccase susbtrate

    Scientific Electronic Library Online (English)

    M, Solís-Oba; E, Bárzana; M, García-Garibay; G, Viniegra-González.

    2007-12-01

    Full Text Available La lacasa comercial obtenida de Myceliophtera termophila y expresada sobre Aspergillus oryzae se empleó para producir un cation radical estable y muy activo del mediador químico ABTS (ácido 2,2'-azino-bis-(3-etillbenzotiazolin-6-sulfonico) con el fin de probar la factibilidad de emplearlo como un in [...] termediario para la oxidación de una variedad de compuestos aromáticos en ausencia de la enzima. Se demostró que el catión radical ABTS•+ por si mismo oxidó al azul índigo, ácido tánico, ácido gálico, azul brillante G, azul de Coomassie, naranja 7 y p-cresol. La reacción de oxidación reveló cambios importantes en sus espectros de absorción en la región del espectro visible. Se demostró también que la oxidación de estos compuestos por la mezcla de lacasa y ABTS se puede efectuar de forma cíclica, de tal forma que la velocidad de reacción fue 94 veces mayor para el índigo, 17 veces mayor para el azul brillante G, 34 veces mayor para el naranja 7 y 5 veces mayor para el p-cresol, comparado con usar el mediador o la lacasa en forma individual. Estos resultados muestran la factibilidad de un esquema de reciclado para la oxidación final de una variedad de compuestos orgánicos en los cuales la enzima no este directamente en contacto con el mismo y que se efectúe a través del mediador ABTS•+. Abstract in english The commercial enzyme laccase cloned from Myceliophtera termophila and expressed in Aspergillus oryzae was used to produce an active, stable and oxidized form of the chemical mediator ABTS (2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid)) in order to test the feasibility of using the monoca [...] tion ABTS•+ as a recyclable intermediate for the oxidation of a variety of aromatic chemicals in the absence of the enzyme. It was shown that ABTS•+, by itself, oxidized, indigo blue, tannic and galic acids, brilliant blue G, Coomassie blue, orange 7 and p-cresol. Oxidation was assessed by important changes in their visible absorption spectra. It was also shown that oxidation of these compounds by a mixture of ABTS and laccase can be done in a cyclic manner, such a way the oxidation rate was 94 times higher for indigo, 17 times for brilliant blue G, 34 times for orange 7 and 5 times higher for p-cresol compared with using the mediator or the laccase alone. Those results show the feasibility of a recycling scheme for the final oxidation of a wide variety of aromatic compounds in which the enzyme is not directly in contact with the compound but through the intermediate ABTS•+.

  15. Hydroxylation of benzoic acid by electrochemical generated hydroxyl radicals

    OpenAIRE

    Oliveira, Raquel; Bento, M. Fátima; Geraldo, M. Dulce

    2012-01-01

    The generation of hydroxyl radicals is an important process in many applications such as organic synthesis [1], oxidative stress studies [2] and detoxification of effluents [3]. Due to the high instability of these radicals they are usually produced in situ by means of different methods, such as disproportionation of peroxynitrous acid or dissociation of hydrogen peroxide by UV action. The generation of hydroxyl radicals based on metal catalyzed decomposition of hydrogen peroxide, Fenton o...

  16. Total Phenolic Content and Free Radical Scavenging Activity of Malva parviflora L. (Malvaceae

    Directory of Open Access Journals (Sweden)

    A.J. Afolayan

    2008-01-01

    Full Text Available The free radical scavenging activity of the methanolic extract of Malva parviflora L. was examined using spectroscopic method against 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH•, radical cation ABTS•+ (2, 2`-azinobis [3-ethylbenzothiazoline-6-sulfonic acid] diammonium salt and the ferric reducing agent. Total phenolic, flavonoid and proanthocyanidin contents were also determined to assess their effects on the antioxidant activity of the extract. The results showed that the methanol extract of M. parviflora differed in its capacity to quench or inhibit DPPH• and ABTS•+. The extract showed a greater ability to quench ABTS•+ by inhibiting 94.3% of the radical cation while it inhibited 9.3% of DPPH•. The free radical scavenging activities were compared using BHT and rutin as reference antioxidants. The plant possessed a higher flavonoid content than phenolics and proanthocyanidins and a positive linear correlation was established between these polyphenols and the free radical scavenging activities.

  17. Free radical scavenging activity of ethanolic extracts from herbs and spices commercialized in Brazil

    OpenAIRE

    Lilian Regina Barros Mariutti; Gisela Pizarro de Mattos Barreto; Neura Bragagnolo; Adriana Zerlotti Mercadante

    2008-01-01

    Ethanolic extracts from 23 different dried herbs and spices commercialized in Brazil were investigated for their free radical scavenging properties using the stable free radicals 2,2'-diphenyl-?-picrylhydrazyl (DPPH•) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS•+), and Trolox as reference (TEAC) for both radicals. The kinetic curves for both radicals showed to follow the first order kinetics model and the decay rate constant (k obs) was calculated. For a...

  18. Free radical scavenging activity of Eagle tea and their flavonoids

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    Qiong Meng

    2012-06-01

    Full Text Available In this study, an online HPLC-DAD-MS coupled with 2,2?-azinobis (3-ethylbenzthiazoline-6-sulfonic acid diammonium salt (ABTS assay was employed for evaluating free radical scavenging activity of Eagle tea and their active components. Twenty-three chromatographic peaks were detected, and nineteen components had free radical scavenging activity. Among them, eight compounds were identified as flavonoids (hyperin, isoquercitrin, quercitrin, quercetin, kaempferol, catechins, chlorogenic acid and epicatechin based on MS data and standard chromatographic characters.

  19. Heterogeneous Reaction of HO2 Radical with Dicarboxylic Acid Particles

    Science.gov (United States)

    Taketani, F.; Kanaya, Y.

    2010-12-01

    HOx(OH+ HO2) radical plays a central role in the tropospheric chemistry. Recently, the heterogeneous loss of HO2 by aerosol particles is a potentially important HOx sink in the troposphere suggested from observation study. However, there have been few studies for loss of HO2 by aerosols. In this study, we measured the HO2 uptake coefficients for four dicarboxylic acids (succinic acid, glutaric acid, adipic acid, and pimelic acid) aerosol particles under ambient conditions (760Torr and 296K) using an aerosol flow tube(AFT) coupled with a chemical conversion /laser-induced fluorescence(CC/LIF) technique. The CC/LIF technique enabled experiments to be performed at almost the same HO2 radical concentration as that in the atmosphere(-10^8 molecules/cm^3). In this system, the effect of the self-reaction of HO2 in the gas phase can be neglected. HO2 radicals were injected into the AFT through a vertically movable Pyrex tube. Injector position dependent profiles of LIF intensity were measured as a function of aerosol concentration at 30% and 70% of relative humilities (RH). Determined HO2 uptake coefficients by succinic acid, glutaric acid, adipic acid, and pimelic acid aerosol particles at 30% RH were 0.05 +/- 0.02, 0.07 +/- 0.03, 0.02 +/- 0.01, and 0.06 +/- 0.03, respectively, while the uptake coefficients by those particles at 70% RH were 0.13 +/- 0.05, 0.13 +/- 0.03, 0.06 +/- 0.01, and 0.11 +/- 0.03, respectively. These results suggest that compositions and relative humidity are significant to the HO2 uptake. We will discuss the potential HO2 loss processes.

  20. Comparative Evaluation of the Radical-Scavenging Activities of Fucoxanthin and Its Stereoisomers

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    Yiping Zhang

    2014-02-01

    Full Text Available Fucoxanthin (Fuco is a characteristic carotenoid of brown seaweeds. In the present study, Fuco and its stereoisomers 9'Z-Fuco, 13Z- and 13'Z-Fuco were extracted from Laminaria japonica Aresch. They were isolated and purified by silica gel column chromatography, Sephadex LH-20, and reversed-phase HPLC. The radical-scavenging activities of the three stereoisomers were evaluated toward 1,1-diphenyl-2-picrylhydrazyl (DPPH radical, 2-2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS radical, hydroxyl radical, and superoxide radical. The order of 1,1-diphenyl-2-picrylhydrazyl (DPPH radical-scavenging activity was 13Z- and 13'Z-Fuco > (all-E-Fuco > 9'Z-Fuco. The order of 2-2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS and hydroxyl radical-scavenging activities were 9'Z-Fuco > (all-E-Fuco > 13Z-and 13'Z-Fuco. The order of superoxide radical-scavenging activity was 13Z- and 13'Z-Fuco > (all-E-Fuco > 9'Z-Fuco. The scavenging activities of Fuco and its stereoisomers toward the four radical types were all dose-dependent. The ABTS, DPPH, and superoxide radical-scavenging activities were all weaker than that of tocopherol (VE, while their hydroxyl radical-scavenging activities were stronger than that of VE. The results confirmed that Fuco and its stereoisomers have potent antioxidant activities.

  1. Antioxidant activity of selected phenols estimated by ABTS and FRAP methods

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    Izabela Biskup

    2013-09-01

    Full Text Available Introduction: Phenols are the most abundant compounds in nature. They are strong antioxidants. Too high level of free radicals leads to cell and tissue damage, which may cause asthma, Alzheimer disease, cancers, etc. Taking phenolics with the diet as supplements or natural medicines is important for homeostasis of the organism. Materials and methods: The ten most popular water soluble phenols were chosen for the experiment to investigate their antioxidant properties using ABTS radical scavenging capacity assay and ferric reducing antioxidant potential (FRAP assay. Results and discussion: Antioxidant properties of selected phenols in the ABTS test expressed as IC50 ranged from 4.332 ?M to 852.713 ?M (for gallic acid and 4- hydroxyphenylacetic acid respectively. Antioxidant properties in the FRAP test are expressed as ?mol Fe2 /ml. All examined phenols reduced ferric ions at concentration 1.00 x 10-3 mg/ml. Both methods are very useful for determination of antioxidant capacity of water soluble phenols.

  2. Uric acid as radical scavenger and antioxidant in the heart.

    Science.gov (United States)

    Becker, B F; Reinholz, N; Ozçelik, T; Leipert, B; Gerlach, E

    1989-11-01

    Uric acid (UA) is released from the heart of many species, including man, and its site of formation has been shown to be the microvascular endothelium. Since UA reacts with oxygen radicals in vitro, experiments were conducted on guinea pig hearts perfused with Krebs-Henseleit buffer (KHB) to evaluate whether the formation of UA could afford protection from damage by radicals and oxidants. The following results were obtained: (1) Upon addition of the hydroxyl radical scavenger DMSO to the perfusate, the coronary rate of release of endogenous uric acid was increased relative to the precursor purines. (2) UA was degraded during passage through the coronary system and also in KHB in vitro after addition of substances generating hydroxyl radicals or hypochlorite. Superoxide (O2-) radicals did not seem to react directly with UA, though UA concentration-dependently quenched the chemiluminescence generated from luminol in the presence of O2- and OH radicals. (3) Coronary dilation by acetylcholine (Ach) and sub-microM concentrations of adenosine, induced by both via endothelial mechanisms, was attenuated after prolonged inhibition of endothelial UA formation by allopurinol. Furthermore, the effect of Ach but not of adenosine proved acutely sensitive to methylene blue and O2-, substances known to inactivate EDRF. This finding suggests involvement of EDRF in Ach-mediated, but not in adenosine-induced dilatation of the intact coronary system. Exogenously applied UA prevented the impairment of vascular responses to Ach and adenosine caused by allopurinol, and to Ach upon generation of O2-. (4) Hearts performed more pressure-volume work and exhibited greater functional stability when perfused with KHB supplemented with UA in a physiological concentration.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2556684

  3. Radical scavenging and antioxidant activities of methanolic extracts from Hypericum species growing in Bulgaria

    OpenAIRE

    ZHELEVA-DIMITROVA, Dimitrina; Nedialkov, Paraskev; Kitanov, Gerassim

    2010-01-01

    Thirteen Hypericum species growing in Bulgaria were investigated for free radical-scavenging activity, antioxidant activity, total tannins and total flavonoids contents. Methanolic extracts from the Hypericum species were analyzed for radical scavenging and antioxidant activities using DPPH-, ABTS- free radicals, total antioxidant activity and inhibition of lipid peroxidation by ferric thiocyanate (FTC) method. Butylated hydroxytoluene and ascorbic acid were used as positive controls. Methano...

  4. Resistance to ABT-737 in activated T lymphocytes: molecular mechanisms and reversibility by inhibition of the calcineurin–NFAT pathway

    OpenAIRE

    Cippà, P E; Kraus, A K; Lindenmeyer, M T; Chen, J.; Guimezanes, A; Bardwell, P. D.; Wekerle, T.; Wüthrich, R.P.; T. Fehr

    2012-01-01

    Dynamic regulation of the intrinsic apoptosis pathway controls central and peripheral lymphocyte deletion, and may interfere with the pro-apoptotic potency of B-cell lymphoma 2 inhibitors such as ABT-737. By following a T-cell receptor (TCR) transgenic population of alloantigen-specific T cells, we found that sensitivity to ABT-737 radically changed during the course of allo-specific immune responses. Particularly, activated T cells were fully resistant to ABT-737 during the first days after ...

  5. Oxidation of hydroxybenzoic acids by •OH radical produced radiolytically

    Science.gov (United States)

    Albarran, Guadalupe; Esparza, Maribel; Mendoza, Edith

    2015-02-01

    The yields of the dihydroxybenzoic acids produced in the radiolytic oxidation of aqueous solutions of the hydroxybenzoic acids were determined to provide information on the concerted effects of -OH and -COOH substituents on the electronic structures of aromatics. Because •OH radical is a strong electrophyl it adds preferentially at the electron rich sites of an aromatic ring. The distribution of hydroxylated products, therefore, gives a measure of the charge distribution in the aromatic. In these studies the hydroxylated cyclohexadienyl radicals initially produced were oxidized to the corresponding dihydroxybenzoic acids by ferricyanide present in the irradiated solution. Product analysis was by chromatographic and electrophoretic methods. It is shown that, as in the case of phenol, the hydroxyl substituent has a dominant ortho-para directing effect that is modified somewhat by the presence of a -COOH substituent. Substantial yields for attack of •OH at the carboxy substituted sites of 2- and 4-hydroxybenzoic acid are also reported. This observation demonstrates that addition of •OH at the ipso positions of carboxylated aromatics can be of considerable importance.

  6. Total Phenolic Content and Free Radical Scavenging Activity of Malva parviflora L. (Malvaceae)

    OpenAIRE

    Afolayan, A. J.; O.M. Aboyade; M.O. Sofidiya

    2008-01-01

    The free radical scavenging activity of the methanolic extract of Malva parviflora L. was examined using spectroscopic method against 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH•), radical cation ABTS•+ (2, 2`-azinobis [3-ethylbenzothiazoline-6-sulfonic acid] diammonium salt) and the ferric reducing agent. Total phenolic, flavonoid and proanthocyanidin contents were also determined to assess their effects on the antioxidant activity of the extract. The results showed that the meth...

  7. Radical scavenging and antioxidant activities of methanolic extracts from Hypericum species growing in Bulgaria

    OpenAIRE

    Zheleva-Dimitrova Dimitrina; Nedialkov Paraskev; Kitanov Gerassim

    2010-01-01

    Thirteen Hypericum species growing in Bulgaria were investigated for free radical-scavenging activity, antioxidant activity, total tannins and total flavonoids contents. Methanolic extracts from the Hypericum species were analyzed for radical scavenging and antioxidant activities using DPPH-, ABTS- free radicals, total antioxidant activity and inhibition of lipid peroxidation by ferric thiocyanate (FTC) method. Butylated hydroxytoluene and ascorbic acid were used as positive controls. Methano...

  8. Pulse radiolytic study of the acid dissociation of OH protons in radicals related to salicylic acid

    International Nuclear Information System (INIS)

    The deprotonation of carboxylated benzosemiquinone radicals prepared by pulse radiolytic oxidation of dihydroxybenzoic acids has been examined by time-resolved absorption spectrophotometry. The pK/sub a/ for dissociation of the OH proton in 3-carboxyl-1,4-benzosemiquinone is found to be 6.47 or 2.4 units higher than that in the unsubstituted radical. This pK/sub a/ is, however, well below that of the OH proton in salicyclic acid (13.6) so that hydrogen bonding is appreciably decreased by the delocalization of the unpaired spin in this radical. Protonation of the basic form of the radical occurs at the diffusion-controlled rate. The rate constant for deprotonation by OH- is relatively low, 4.7 X 107 M-1 s-1, so that reaction with base becomes important only above pH 10. As a result this radical provides an excellent system for studying acid-base equilibration processes in near neutral solutions. Azide ion is shown to be an efficient catalyst which allows the acid-base equilibrium to be examined on the 10-?s time scale. Deprotonation is also catalyzed by the dihydroxybenzoic acid used as the radical source. Analogous studies on 4-carboxy-1,3-benzosemiquinone give the pK/sub a/ as 7.9. In spite of this high pK/sub a/, which indicates the rate constant for spontaneous dissociation of this radical to be > 103 s-1, the rate constant for deprotonation by OH-, 4.9 X 108 M-1 s8 M-1 s-1, is considerably higher than in the case of 3-carboxy-1,4-benzosemiquinone

  9. Hydroxyl radical substitution in halogenated carbonyls: oxalic acid formation.

    Science.gov (United States)

    Christiansen, Carrie J; Dalal, Shakeel S; Francisco, Joseph S; Mebel, Alexander M; Gaffney, Jeffrey S

    2010-03-01

    An ab initio study of OH radical substitution reactions in halogenated carbonyls is conducted. Hydroxyl radical substitution into oxalyl dichloride [ClC(O)C(O)Cl] and oxalyl dibromide [BrC(O)C(O)Br], resulting in the formation of oxalic acid, is presented. Analogous substitution reactions in formyl chloride [ClCH(O)], acetyl chloride [ClC(O)CH(3)], formyl bromide [BrCH(O)], and acetyl bromide [BrC(O)CH(3)] are considered. Energetics of competing hydrogen abstraction reactions for all applicable species are computed for comparison. Geometry optimizations and frequency computations are performed using the second-order Møller-Plesset perturbation theory (MP2) and the 6-31G(d) basis set for all minimum species and transition states. Single point energy computations are performed using fourth-order Møller-Plesset perturbation theory (MP4) and coupled cluster theory [CCSD(T)]. Potential energy surfaces, including activation energies and enthalpies, are determined from the computations. These potential energy surfaces show that OH substitution into ClC(O)C(O)Cl and BrC(O)C(O)Br, resulting in the formation of oxalic acid and other minor products, is energetically favorable. Energetics of analogous reactions with ClCH(O), BrCH(O), ClC(O)CH(3), and BrC(O)CH(3) are also computed. PMID:20131850

  10. Extracellular ABTS-oxidizing activity of autochthonous fungal strains from Argentina in solid medium.

    Science.gov (United States)

    Saparrat, M C; Margarita-Bucsinszky, A M; Alfio-Tournier, H; Cabello, M N; Arambarri, A M

    2000-06-01

    The screening for extracellular oxidases and peroxidases from autochthonous filamentous fungi isolated from different substrates is an important step towards the detection of extracellular fungal oxidative systems. Thirty-one autochthonous fungal strains from Argentina, belonging to different ecophysiological and taxonomic groups, were plate-screened for their ability to produce extracellular oxidoreductases. Modified Kirk solid medium containing the chromogen 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) was used to determine the presence of this extracellular activity. The fungi tested were grouped according to the colour intensity of the modified Kirk medium in: a) species without extracellular ABTS-oxidizing activity; b) species with low extracellular ABTS-oxidizing activity; c) species with moderate extracellular ABTS-oxidizing activity; d) species with high extracellular ABTS-oxidizing activity. The assay revealed extracellular ABTS-oxidizing activity in 90% of the strains tested. All species of Basidiomycetes used exhibited ABTS-oxidizing activity, except Laeticorticium roseum. Aspergillus terreus and Epicoccum purpurascens (Deuteromycetes) did not show extracellular oxidative activity on ABTS. Agrocybe aegerita, Amauroderma boleticeum, Cladosporium cladosporioides, Coriolopsis rigida, Grammothele subargentea, Graphium putredinis, Hexagona hydnoides, Hexagona papyraceae, Loweporus lividus, Peniophora albobadia, Phellinus everhartii, Phellinus gilvus; Phellinus linteus; Pleurotus laciniatocrenatus, Pycnoporus sanguineus, Rigidoporus ulmarius, Steccherinum rawakense, Talaromyces helicus, Trametes elegans, Trametes pavonia, Trametes villosa and Trichaptum sector are reported here for the first time as species capable of producing ABTS-oxidizing extracellular oxidorreductases. PMID:15813698

  11. EPR study of gamma induced radicals in amino and iminodiacetic acid derivatives

    Scientific Electronic Library Online (English)

    Murat, Aydin; M. Halim, Baskan; M. Y., Emre Osmanoglu.

    2009-09-01

    Full Text Available In this study, electron paramagnetic resonance spectroscopy was used to investigate free radicals formed in gamma irradiated L-glutamine hydrochloride, iminodiacetic acid hydrochloride and N-(2-hyroxyethyl) iminodiacetic acid powders. The free radicals produced in L-glutamine hydrochloride powders w [...] ere attributed to the CH2CHCOOH radical; and those in iminodiacetic acid hydrochloride and N-(2-hyroxyethyl) iminodiacetic acid powders to the HNCHCH2(COOH)2 and HOCH2CH2NCHCH2(COOH)2, respectively. The g-values of the radicals and the hyperfine structure constants of the free electron with the environmental protons and 14N nucleus were determined. The samples were not displayed before they were not irradiated. The free radicals were found stable at room temperature for more than six months. Some spectroscopic properties and suggestions concerning possible structure of the radicals are discussed in this paper.

  12. EPR study of gamma induced radicals in amino and iminodiacetic acid derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, Murat [Adiyaman University (Turkey). Faculty of Education; Baskan, M. Halim [Dicle University, Diyarbakir (Turkey). Faculty of Education; Osmanoglu, Y. Emre [Dicle University, Diyarbakir (Turkey). Inst. of Science

    2009-09-15

    In this study, electron paramagnetic resonance spectroscopy was used to investigate free radicals formed in gamma irradiated L-glutamine hydrochloride, iminodiacetic acid hydrochloride and N-(2-hydroxyethyl) iminodiacetic acid powders. The free radicals produced in L-glutamine hydrochloride powders were attributed to the CH{sub 2}CHCOOH radical; and those in iminodiacetic acid hydrochloride and N-(2-hydroxyethyl) iminodiacetic acid powders to the HNCHCH{sub 2}(CO OH){sub 2} and HOCH{sub 2}CH{sub 2}NCHCH{sub 2}(CO OH){sub 2}, respectively. The g-values of the radicals and the hyperfine structure constants of the free electron with the environmental protons and {sup 14}N nucleus were determined. The samples were not displayed before they were not irradiated. The free radicals were found stable at room temperature for more than six months. Some spectroscopic properties and suggestions concerning possible structure of the radicals are discussed in this paper. (author)

  13. EPR study of gamma induced radicals in amino and iminodiacetic acid derivatives

    International Nuclear Information System (INIS)

    In this study, electron paramagnetic resonance spectroscopy was used to investigate free radicals formed in gamma irradiated L-glutamine hydrochloride, iminodiacetic acid hydrochloride and N-(2-hydroxyethyl) iminodiacetic acid powders. The free radicals produced in L-glutamine hydrochloride powders were attributed to the CH2CHCOOH radical; and those in iminodiacetic acid hydrochloride and N-(2-hydroxyethyl) iminodiacetic acid powders to the HNCHCH2(CO OH)2 and HOCH2CH2NCHCH2(CO OH)2, respectively. The g-values of the radicals and the hyperfine structure constants of the free electron with the environmental protons and 14N nucleus were determined. The samples were not displayed before they were not irradiated. The free radicals were found stable at room temperature for more than six months. Some spectroscopic properties and suggestions concerning possible structure of the radicals are discussed in this paper. (author)

  14. Reactions of linoleic acid peroxyl radicals with phenolic antioxidants: a pulse radiolysis study

    International Nuclear Information System (INIS)

    Linoleic acid peroxyl radicals (LOO) can be viewed as model intermediates occurring during lipid peroxidation processes. Formation and reactions of these species were investigated in aqueous alkaline solution using pulse radiolysis combined with kinetic spectroscopy. Irradiation of linoleic acid in N2O/O2-saturated solutions leads to a mixture of peroxyl radical isomers; reaction of 13-hydroperoxylinoleic acid (13-LOOH) with azide radicals in N2O-saturated solution produces 13-LOO radicals specifically. These peroxyl radicals cannot be observed directly, but their reactions with kaempferol and quercetin, acting as radical-scavenging antioxidants, produced strongly absorbing aroxyl radicals (ArO). The same aroxyl radicals were generated by OH and N3 with rate constants exceeding 109 dm3 mol-1 s-1. Applying a reaction scheme that includes competing generation and decay reactions of both LOO and ArO radicals, individual rate constants were derived for LOO reactions with the phenols (> 107 dm3 mol-1 s-?1), with aroxyl radicals to form covalent adducts (> 108 dm3 mol-1 s-1), as well as for their bimilecular decay (3.0 x 108 dm3 mol-1 s-1). These results demonstrate high reactivity of fatty acid peroxyl radicals and flavone antioxidants in aqueous solution. flavone antioxidants in aqueous solution. (author)

  15. ESR studies of radiation induced radical products from linoleic acid and linolenic acid and the radioprotective effect by ?-tocopherol

    International Nuclear Information System (INIS)

    Primary radicals from the ?-radiolysis of air-saturated linoleic acid and linolenic acid at 77 K, and the subsequent secondary radicals appeared during the course of variable temperature elevation were investigated by ESR. The ESR spectrum from samples irradiated and observed at 77 K shows the presence of the radical anion doublet arise from the electron adducts of the carboxy groups and the poorly resolved broad singlet results from some carbon-centered radicals. Annealing to approximately 125 K which allows for molecular oxygen migration results in the formation of peroxyl radicals. At 247 K, the ESR spectrum is a multi-line pattern which is attributable to structure of the ?-carbon radical superimposed on the pentadienyl radicals. The ESR spectra from linoleic acid-?-tocopherol and linolenic acid-?-tocopherol binary systems irradiated at 77 K and recorded at 140 K or 215 K revealed the characteristic similarity to that from ?-tocopherol alone, no trace of ESR signal from either peroxyl or the composite pattern from superposition of pentadienyl radical and ?-carbon radicals can be found out. Therefore ?-tocopherol has exerted radioprotection effect on peroxidation of linoleic acid and linolenic acid

  16. Detection of free radicals produced from the reaction of cytochrome P-450 with linoleic acid hydroperoxide.

    Science.gov (United States)

    Rota, C; Barr, D P; Martin, M V; Guengerich, F P; Tomasi, A; Mason, R P

    1997-12-01

    The ESR spin-trapping technique was employed to investigate the reaction of rabbit cytochrome P-450 1A2 (P450) with linoleic acid hydroperoxide. This system was compared with chemical systems where FeSO4 or FeCl3 was used in place of P450. The spin trap 5, 5'-dimethyl-1-pyrroline N-oxide (DMPO) was employed to detect and identify radical species. The DMPO adducts of hydroxyl, O2-., peroxyl, methyl and acyl radicals were detected in the P450 system. The reaction did not require NADPH-cytochrome P-450 reductase or NADPH. The same DMPO-radical adducts were detected in the FeSO4 system. Only DMPO-.OH radical adduct and carbon-centred radical adducts were detected in the FeCl3 system. Peroxyl radical production was completely O2-dependent. We propose that polyunsaturated fatty acids are initially reduced to form alkoxyl radicals, which then undergo intramolecular rearrangement to form epoxyalkyl radicals. Each epoxyalkyl radical reacts with O2, forming a peroxyl radical. Subsequent unimolecular decomposition of this peroxyl radical eliminates O2-. radical. PMID:9371716

  17. Endogenous released ascorbic acid suppresses ethanol-induced hydroxyl radical production in rat striatum.

    Science.gov (United States)

    Huang, Mei; Liu, Wen; Li, Qiang; Wu, Chun Fu

    2002-07-19

    Previous studies have shown that acute systemic administration of ethanol induced ascorbic acid release in the striatum. However, the pharmacological implications of ethanol-induced striatal ascorbic acid release are unclear. In the present study, ethanol-induced extracellular changes of ascorbic acid and hydroxyl radical levels were detected in rat striatum by using brain microdialysis coupled to high-performance liquid chromatography with electrochemical detection. It was found that both in male and female rats, ethanol (3.0 g/kg, i.p.) increased striatal ascorbic acid release in the first 60 min after ethanol administration. Meanwhile, the extracellular hydroxyl radical levels, detected as 2,3- and 2,5-DHBA, were significantly decreased. However, when the ascorbic acid levels returned to the baseline, hydroxyl radical levels rebounded. Administration of DL-fenfluramine (20 mg/kg, i.p.) had no effect on the basal levels of ascorbic acid and hydroxyl radical, but significantly blocked ethanol-induced ascorbic acid release and increased hydroxyl radical levels significantly. Exogenous administration of ascorbic acid (20 mg/kg, s.c.) increased the extracellular levels of ascorbic acid in the striatum, and inhibited the increase of 2,3- and 2,5-DHBA in DL-fenfluramine plus ethanol group. These results provide first evidence that release of endogenous ascorbic acid in the striatum plays an important role in preventing oxidative stress by trapping hydroxyl radical in the central nervous system. PMID:12106669

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

    International Nuclear Information System (INIS)

    The interaction of caffeic acid with eaq-, (CH3)2(OH) CCH2·, CO2·-, H·, ·OH and N3· radicals were studied by ?-, 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)

  19. Formyl radicals in x-irradiated frozen aqueous solutions of DNA and nucleic acids constituents

    International Nuclear Information System (INIS)

    Frozen aqueous solutions of DNA and nucleic acids constituents have been x-irradiated at 770K and observed by electron spin resonance. In nearly all the sugar-containing compounds the characteristic doublet due to formyl radicals is observed along with other spectral components. It was concluded that HCO radicals arise from pentose ring breakage, which may occur even at 770K. According to the proposed scheme, the free radicals would be induced either by direct or indirect effects

  20. Test for antioxidant ability by scavenging long-lived mutagenic radicals in mammalian cells and by blood test with intentional radicals: an application of gallic acid

    OpenAIRE

    Kumagai, Jun; Kawaura, Tomoko; Miyazaki, Tetsuo; Prost, Michel; Prost, Emmanuelle; Watanabe,Masami; Quetin-Leclercq, Joëlle

    2003-01-01

    Antioxidant ability of gallic acid (GA) are determined both by electron spin resonance measurement of long-lived radicals produced in gamma-ray irradiated Syrian golden hamster embryo cells with GA and by hemolysis measurement with GA when blood cells are submitted to radicals. Scavenging properties of GA are determined by the reaction rate constant with long-lived mutagenic radicals in the cells while the blood test allows to analyze the global effects of this compound: radical scavenger + m...

  1. Decarboxylative C-H arylation of benzoic acids under radical conditions.

    Science.gov (United States)

    Seo, Sangwon; Slater, Mark; Greaney, Michael F

    2012-05-18

    A decarboxylative radical cyclization reaction has been developed for the synthesis of fluorenones. The reaction uses Ag(I)/K2S2O8 to oxidatively decarboxylate an aroylbenzoic acid to an aryl radical, which undergoes cyclization to afford fluorenone products in good yield. PMID:22571756

  2. Oxidation of carboxylic acids regenerates hydroxyl radicals in the unpolluted and nighttime troposphere.

    Science.gov (United States)

    da Silva, Gabriel

    2010-07-01

    The hydroxyl radical (OH) controls the removal of organic compounds from the troposphere. Atmospheric chemistry models significantly under-predict OH levels in unpolluted environments, implying that they are regenerated via some unknown mechanism(s). This work uses computational chemistry to demonstrate that the photochemical oxidation of alkyl carboxylic acids can efficiently regenerate the hydroxyl radical via unimolecular decomposition of alpha-carboxyalkylperoxy radicals. For acetic acid and propanoic acid the proposed mechanism is predicted to dominate in the unpolluted lower troposphere, and it may also operate to some extent in the mid to upper troposphere. Alkyl carboxylic acids are also predicted to act as a new source of nighttime OH throughout the planetary boundary layer, where OH levels are also under-predicted. The thermodynamic requirements for reactions of this class are discussed, and some candidate OH-reforming molecules particularly relevant to aromatic photooxidation are identified. Adopting a broader perspective, the alpha-carboxyalkyl radical precursors that react with O(2) to form the unstable alpha-carboxyalkylperoxy type radicals are also expected to form during combustion, in the interstellar medium, and from the gamma-irradiation of glycine and related amino acids, and the potential importance of this new chemistry in these environments is discussed. Master equation simulations suggest that alpha-carboxyalkyl + O(2) reactions provide a prompt OH source during the autoignition and combustion of biodiesel and other oxygenated biofuels, where carboxylic acids are formed as early stage oxidation products. Ketene combustion is also thought to proceed via these OH-reforming alpha-carboxyalkyl radicals. The in vivo formation of alpha-carboxyalkylperoxy radicals followed by oxidation to the highly reactive OH radical may induce oxidative stress in the human body, in a process initiated by gamma-rays. Finally, the reaction of ketenes with OH to form alpha-carboxyalkyl radicals, followed by addition of NH(2) or related species, is suggested as a new extraterrestrial pathway to amino acids. PMID:20533840

  3. Measurement of antioxidant activity with trifluoperazine dihydrochloride radical cation

    Scientific Electronic Library Online (English)

    M.N., Asghar; I.U., Khan.

    2008-06-01

    Full Text Available A novel, rapid and cost-effective trifluoperazine dihydrochloride (TFPH) decolorization assay is described for the screening of antioxidant activity. A chromogenic reaction between TFPH and potassium persulfate at low pH produces an orange-red radical cation with maximum absorption at 502 nm in its [...] first-order derivative spectrum. TFPH was dissolved in distilled water to give a 100 mM solution. The TFPH radical cation solution was made by reacting 0.5 mL of the solution with K2S2O8 (final concentration: 0.1 mM) and diluting to 100 mL with 4 M H2SO4 solution. A linear inhibition of color production was observed with linearly increasing amounts of antioxidants, with correlation coefficients (R²) ranging from 0.999 to 0.983. The antioxidant capacity of standard solutions of an antioxidant was evaluated by comparing with the inhibition curve using Trolox as the standard. Comparison of antioxidant capacity determined with this newly developed TFPH assay and with the well-known 2,2'-azinobis-[3-ethylbenzthiazoline-6-sulfonic acid] (ABTS)-persulfate decolorization assay indicated the efficacy and sensitivity of the procedure. The proposed assay is less expensive (costs about US$4 per 100 assays) and requires only 20 min for preparation of radical cation solution in comparison with ABTS assay, in which almost 12-16 h are required for preparation of a stable ABTS radical cation solution. The present assay has the advantage over ABTS assay that it can be used to measure the antioxidant activity of the samples, which are naturally found at a pH as low as 1, because the radical cation itself has been stabilized at low pH.

  4. Measurement of antioxidant activity with trifluoperazine dihydrochloride radical cation

    Directory of Open Access Journals (Sweden)

    M.N. Asghar

    2008-06-01

    Full Text Available A novel, rapid and cost-effective trifluoperazine dihydrochloride (TFPH decolorization assay is described for the screening of antioxidant activity. A chromogenic reaction between TFPH and potassium persulfate at low pH produces an orange-red radical cation with maximum absorption at 502 nm in its first-order derivative spectrum. TFPH was dissolved in distilled water to give a 100 mM solution. The TFPH radical cation solution was made by reacting 0.5 mL of the solution with K2S2O8 (final concentration: 0.1 mM and diluting to 100 mL with 4 M H2SO4 solution. A linear inhibition of color production was observed with linearly increasing amounts of antioxidants, with correlation coefficients (R² ranging from 0.999 to 0.983. The antioxidant capacity of standard solutions of an antioxidant was evaluated by comparing with the inhibition curve using Trolox as the standard. Comparison of antioxidant capacity determined with this newly developed TFPH assay and with the well-known 2,2'-azinobis-[3-ethylbenzthiazoline-6-sulfonic acid] (ABTS-persulfate decolorization assay indicated the efficacy and sensitivity of the procedure. The proposed assay is less expensive (costs about US$4 per 100 assays and requires only 20 min for preparation of radical cation solution in comparison with ABTS assay, in which almost 12-16 h are required for preparation of a stable ABTS radical cation solution. The present assay has the advantage over ABTS assay that it can be used to measure the antioxidant activity of the samples, which are naturally found at a pH as low as 1, because the radical cation itself has been stabilized at low pH.

  5. Measurement of antioxidant activity with trifluoperazine dihydrochloride radical cation.

    Science.gov (United States)

    Asghar, M N; Khan, I U

    2008-06-01

    A novel, rapid and cost-effective trifluoperazine dihydrochloride (TFPH) decolorization assay is described for the screening of antioxidant activity. A chromogenic reaction between TFPH and potassium persulfate at low pH produces an orange-red radical cation with maximum absorption at 502 nm in its first-order derivative spectrum. TFPH was dissolved in distilled water to give a 100 mM solution. The TFPH radical cation solution was made by reacting 0.5 mL of the solution with K2S2O8 (final concentration: 0.1 mM) and diluting to 100 mL with 4 M H2SO4 solution. A linear inhibition of color production was observed with linearly increasing amounts of antioxidants, with correlation coefficients (R(2)) ranging from 0.999 to 0.983. The antioxidant capacity of standard solutions of an antioxidant was evaluated by comparing with the inhibition curve using Trolox as the standard. Comparison of antioxidant capacity determined with this newly developed TFPH assay and with the well-known 2,2'-azinobis-[3-ethylbenzthiazoline-6-sulfonic acid] (ABTS)-persulfate decolorization assay indicated the efficacy and sensitivity of the procedure. The proposed assay is less expensive (costs about US$4 per 100 assays) and requires only 20 min for preparation of radical cation solution in comparison with ABTS assay, in which almost 12-16 h are required for preparation of a stable ABTS radical cation solution. The present assay has the advantage over ABTS assay that it can be used to measure the antioxidant activity of the samples, which are naturally found at a pH as low as 1, because the radical cation itself has been stabilized at low pH. PMID:18622491

  6. Comparison of a novel extraction-based colorimetric (ABTS) method with membrane introduction mass spectrometry (MIMS): trichloramine dynamics in pool water.

    Science.gov (United States)

    Soltermann, Fabian; Widler, Tobias; Canonica, Silvio; von Gunten, Urs

    2014-07-01

    Trichloramine is a hazardous disinfection by-product, which is present in chlorinated swimming pools. Although it is primarily taken up by inhalation, the concentration in pool water is important to monitor pool water quality and to assess trichloramine mitigation strategies. To date, scarce data is available on trichloramine concentration in pool water due to the lack of a suitable and easily applicable analytical method. This study presents a novel low cost, colorimetric method which is easy to operate and suitable for on-site measurements of trichloramine concentrations ?0.05 ?M (?0.01 mg L(-1) as Cl2). The analytical method (termed "extraction-based ABTS method") consists of, (i) trichloramine stripping from pool water samples, (ii) passing it through a solid phase filter, composed of silica gel impregnated with sulfamic acid to eliminate interferences and (iii) trichloramine reaction with the indicator 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) to produce the coloured ABTS(•-) radical, which is measured at ? = 405 nm to determine the trichloramine concentration in the pool water sample. A comparison of the extraction-based ABTS method with membrane introduction mass spectrometry (MIMS) for 28 pool samples revealed a good correlation of the two methods. The trichloramine concentration in pool samples is correlated to HOCl, which is the most important factor for its formation. Other parameters such as combined chlorine and pH play a minor role while no correlation between trichloramine and the urea or the TOC concentration was observed. On-site measurements with MIMS in a wading pool over 6 days with a time resolution of 1 h confirmed that trichloramine concentrations strongly responded to changes in free chlorine concentrations. A diurnal measurement of trichloramine with a time resolution of 20 min revealed that trichloramine concentrations reacted quickly and sensitively to the bather load and that urea is probably not the main precursor for its formation. PMID:24769062

  7. Free radicals produced by the oxidation of gallic acid: An electron paramagnetic resonance study

    OpenAIRE

    Wagner Brett A; Pasanphan Wanvimol; Eslami Angelique C; Buettner Garry R

    2010-01-01

    Abstract Background Gallic acid (3,4,5-trihydroxybenzoic acid) is found in a wide variety of plants; it is extensively used in tanning, ink dyes, as well as in the manufacturing of paper. The gallate moiety is a key component of many functional phytochemicals. In this work electron paramagnetic spectroscopy (EPR) was used to detect the free radicals generated by the air-oxidation of gallic acid. Results We found that gallic acid produces two different radicals as a function of pH. In the pH r...

  8. Picosecond Pulse Radiolysis of Highly Concentrated Phosphoric Acid Solutions: Mechanism of Phosphate Radical Formation.

    Science.gov (United States)

    Ma, Jun; Schmidhammer, Uli; Mostafavi, Mehran

    2015-06-18

    Eight solutions containing phosphoric acid with concentrations ranging from 2 mol L(-1) to neat acid have been studied by picosecond pulse radiolysis. The absorbance of the secondary radical H2PO4(•) formed within 7 ps of the electron pulse is observed using pulse-probe method in the visible. Kinetic analysis shows that the radicals of phosphoric acid are formed via two mechanisms: direct electron detachment and oxidation by the radical cation of water, H2O(•+). On the basis of molar extinction coefficient value of 1850 L mol(-1) cm(-1), at 15 ps the radiolytic yield of H2PO4(•) formation by direct energy absorption is 3.7 ± 0.1 × 10(-7) mol J(-1) in neat phosphoric acid. In highly concentrated phosphoric acid solutions, the total yield of phosphate radical at 15 ps exhibits an additional contribution that can be explained by electron transfer from phosphoric acid to H2O(•+). The efficiency of the electron transfer to this strongly oxidizing species in phosphoric acid solutions is lower compared with the one in sulfuric acid solutions. Two explanations are given to account for a relatively low efficiency of H2O(•+) scavenging in concentrated phosphoric acid solutions. PMID:25176139

  9. Discriminating D-amino acid-containing peptide epimers by radical-directed dissociation mass spectrometry.

    Science.gov (United States)

    Tao, Yuanqi; Quebbemann, Neil R; Julian, Ryan R

    2012-08-01

    The presence of a single D-amino acid in a peptide is very difficult to detect. Mass spectrometry-based approaches rely on differences in fragmentation between all L-amino acid-containing peptides and single D-amino acid-containing peptides (which are epimers) for identification. The success of this approach is dependent on the structural sensitivity of the fragmentation method. Recently, experiments have demonstrated that fragmentation initiated by radical chemistry, or radical-directed dissociation (RDD), is particularly sensitive to the structure of the ion being fragmented. Herein, RDD is used to identify the presence of D-serine, D-alanine, or D-aspartic acid in eight biologically relevant peptides. It is demonstrated that chiral disambiguation by RDD is dependent on both the initial radical site and subsequent radical migration. Fortuitously, RDD can be initiated by a variety of different radical precursors which can be associated with the peptide via covalent or noncovalent means, and RDD can be examined in all observable charge states (both positive and negative). This diversity enables numerous initial radical sites and migration pathways to be explored. For all but one of the peptides that were examined, RDD provides significantly better chiral discrimination than CID. Quantitation of peptide epimers by RDD is also described. PMID:22812429

  10. Rate and mechanism of the reaction of hydroxyl radicals with formic and deuteriated formic acids

    International Nuclear Information System (INIS)

    Rate constants for the reactions of hydroxyl radicals with the monomer and dimer of formic acid and deuteriated formic acids have been determined in the temperature range 297-445 K by a laser photolysis-resonance absorption technique. Hydroxyl radicals were generated by photolysis of formic acid at 222 nm with a KrCl excimer laser and were monitored by time-resolved resonance absorption. In each case the rate constant of the monomer of formic acid was much larger than that of the dimer, and a large isotope effect was observed when the carboxylic, but not the formyl, hydrogen was substituted by deuterium. A two-channel mechanism is proposed, one involving formation of a hydrogen-bonded adduct followed by transfer of the carboxylic hydrogen to the hydroxyl radical, and the other, direct abstraction of a formyl hydrogen. 31 refs., 2 figs. 1 tab

  11. Reaction of thiyl radicals with alcohols, ethers and polyunsaturated fatty acids: A possible role of thiyl free radicals in thiol mutagenesis?

    International Nuclear Information System (INIS)

    Possible reactions of thiyl free radicals in biological environment are reviewed. In particular hydrogen transfer processes from model C-H compounds like alcohols and ethers as well as from polyunsaturated fatty acids to thiyl radicals are described to proceed with reasonably high rate constants (103-104 and 106-107 M-1 s-1, respectively). Thiyl radicals have thus to be considered as potentially hazardous species especially with respect to DNA damage and lipid peroxidation. (orig.)

  12. Identification of free radicals induced by gamma irradiation in amino acid derivatives

    International Nuclear Information System (INIS)

    Powders of N-acetyl-L-leucine and N-methyl-L-glutamic acid were gamma irradiated and the free radicals formed were investigated at room temperature by electron paramagnetic resonance technique. The free radicals formed in compounds were attributed to the (CH3)2CCH CH2CH(NHCOCH3)COOH and HOOCCH2CH2C(NHCH3)COOH radicals respectively. Both radicals are very stable and we could observe them for five months without almost intensity diminution at room temperature. The g values of the radicals and the hyperfine structure constants of the free electron with nearby protons and 14N nucleus were determined. The results were found to be in good agreement with the existing literature data. (author)

  13. Study of the structure of free radicals in gamma irradiated amino acid derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, Murat, E-mail: maydin@adiyaman.edu.t [Adyyaman University, Adyaman (Turkey). Faculty of Education

    2010-12-15

    Electron paramagnetic resonance spectroscopy has been used for the study of the free radicals produced in the powders of L-arginine monohydrochloride, ala-ala and DL-{beta}-leucine gamma-irradiated at room temperature. The structures of the radicals formed in compounds were determined as NH{sub 2}(NH)NHCHCH{sub 2}CH{sub 2}CH(NH{sub 2})CO OH, CH{sub 3}CHCOOH and (CH{sub 3}){sub 2} CCH(NH{sub 2})CH{sub 2}COOH respectively. The paramagnetic species were found to be stable at room temperature more than three months. It was determined that unpaired electron interacted with nearby protons and {sup 14}N nucleus in these radicals. The g values of the radicals and the hyperfine structure constants of the free electron were also measured. These results were compared with the earlier studies in amino acid and derivatives radicals and discussed. (author)

  14. Study of the structure of free radicals in gamma: irradiated amino acid derivatives

    Scientific Electronic Library Online (English)

    Murat, Aydin.

    2010-12-01

    Full Text Available Electron paramagnetic resonance spectroscopy has been used for the study of the free radicals produced in the powders of L-arginine monohydrochloride, ala-ala and DL-?-leucine gamma-irradiated at room temperature. The structures of the radicals formed in compounds were determined as NH2(NH)NHCHCH2CH [...] 2CH(NH2)COOH, CH3CHCOOH and (CH3)2C CH(NH2)CH2COOH respectively. The paramagnetic species were found to be stable at room temperature more than three months. It was determined that unpaired electron interacted with nearby protons and 14N nucleus in these radicals. The g values of the radicals and the hyperfine structure constants of the free electron were also measured. These results were compared with the earlier studies in amino acid and derivatives radicals and discussed.

  15. Spin trapping study on the nature of radicals generated by X radiolysis and peroxidation of linolenic acid

    International Nuclear Information System (INIS)

    The radicals of linolenic acid and their spin adducts (SA) with PBN formed during X radiolysis of linolenic acid and in lipid peroxidation with ferrous ions were investigated and identified. It was found that in the absence of oxygen in pure linolenic acid at 77 K X irradiation produces alkyl and carboxyl radicals. In the presence of the spin trap alkyl radical spin adducts were formed. Irradiation of linolenic acid in the presence of oxygen at 77 K also resulted in the formation of alkyl radicals. These radicals were transformed into peroxy radicals in the interaction of alkyl radical with oxygen upon heating to 117 K. In the presence of spin trap X irradiation of linolenic acid and heating of the sample up to 300 K gave rise to EPR spectra of SA alkyl and unidentified radicals. Lipid peroxidation of linolenic acid induced by ferrous ions in the presence of spin trap also formed radicals and SA of linolenic acid. The spectral parameters of SA generated with ferrous ions in lipid peroxidation and of those generated during X radiolysis do not differ. The similarity of spectral parameters of SA in these two cases suggests a similarity in the structure of linolenic acid radicals. (author)

  16. Pyrite-induced hydroxyl radical formation and its effect on nucleic acids

    OpenAIRE

    Leifer Nicole; Wimmer Eckard; Mueller Steffen; Cohn Corey A; Greenbaum Steven; Strongin Daniel R; Schoonen Martin AA

    2006-01-01

    Abstract Background Pyrite, the most abundant metal sulphide on Earth, is known to spontaneously form hydrogen peroxide when exposed to water. In this study the hypothesis that pyrite-induced hydrogen peroxide is transformed to hydroxyl radicals is tested. Results Using a combination of electron spin resonance (ESR) spin-trapping techniques and scavenging reactions involving nucleic acids, the formation of hydroxyl radicals in pyrite/aqueous suspensions is demonstrated. The addition of EDTA t...

  17. Complexation of allyl radicals and hydrochloric acid in helium nanodroplets.

    Science.gov (United States)

    Leicht, Daniel; Habig, Daniel; Schwaab, Gerhard; Havenith, Martina

    2015-02-12

    Infrared spectra of the allyl radical-HCl complex in superfluid helium nanodroplets have been recorded in the IR frequency range of 2750-3120 cm(-1). Six fundamental bands were observed, five of which have been assigned to the C-H stretch vibrations of the allyl radical. No additional CH bands were observed upon the binding of HCl. The band at 2800.3 cm(-1) can unambiguously be assigned to the bound HCl stretch, which is red-shifted by 106 cm(-1) compared to that of the free HCl. Stark spectra and pickup curves were recorded and support our assignment. In accompanying ab initio calculations, we found four equivalent minima and computed a two-dimensional potential energy surface for the HCl positioning on the allyl radical plane at the CCSD(T)/TZVPP level. Based on our findings, we conclude that the ground-state structure of the complex shows two energetically equivalent T-shaped minimum structures. Because of small barriers between the two minima, a delocalization of the HCl is anticipated. PMID:25597230

  18. Test for antioxidant ability by scavenging long-lived mutagenic radicals in mammalian cells and by blood test with intentional radicals: an application of gallic acid

    International Nuclear Information System (INIS)

    Antioxidant ability of gallic acid (GA) are determined both by electron spin resonance measurement of long-lived radicals produced in ?-ray irradiated Syrian golden hamster embryo cells with GA and by hemolysis measurement with GA when blood cells are submitted to radicals. Scavenging properties of GA are determined by the reaction rate constant with long-lived mutagenic radicals in the cells while the blood test allows to analyze the global effects of this compound: radical scavenger+metal ion chelator+regeneration of intra- and extra-cellular antioxidant

  19. Test for antioxidant ability by scavenging long-lived mutagenic radicals in mammalian cells and by blood test with intentional radicals: an application of gallic acid

    Science.gov (United States)

    Kumagai, Jun; Kawaura, Tomoko; Miyazaki, Tetsuo; Prost, Michel; Prost, Emmanuelle; Watanabe, Masami; Quetin-Leclercq, Joëlle

    2003-01-01

    Antioxidant ability of gallic acid (GA) are determined both by electron spin resonance measurement of long-lived radicals produced in ?-ray irradiated Syrian golden hamster embryo cells with GA and by hemolysis measurement with GA when blood cells are submitted to radicals. Scavenging properties of GA are determined by the reaction rate constant with long-lived mutagenic radicals in the cells while the blood test allows to analyze the global effects of this compound: radical scavenger+metal ion chelator+regeneration of intra- and extra-cellular antioxidant.

  20. Concerted effects in the reaction of ·OH radicals with aromatics: radiolytic oxidation of salicylic acid

    International Nuclear Information System (INIS)

    Liquid chromatographic and capillary electrophoretic studies have been used to resolve the products produced in the radiolytic oxidation of salicylic acid in aqueous solution. These studies have shown that, as in the case of phenol, ·OH radicals preferentially add to the positions ortho and para to the OH substituent. However, in contrast to its reaction with phenol, addition at the ortho position is favored over addition at the para position. Because ·OH radical is a strong electrophile this difference suggests that the electron population at the ortho position in the salicylate anion is enhanced as a result of the hydrogen bonding in salicylic acid

  1. Biotechnological treatment for colorless denim and textil wastewater treatment with laccase and ABTS / Tratamiento biotecnológico para la decoloración de la mezclilla y efluentes textiles empleando lacasa y ABTS

    Scientific Electronic Library Online (English)

    Myrna, SOLÍS-OBA; Javier, ALMENDÁRIZ; Gustavo, VINIEGRA-GONZÁLEZ.

    2008-03-01

    Full Text Available El sistema ABTS (ácido 2,2'-[3-etil benzotiazolin-6-sulfónico])-lacasa se empleó para decolorar tanto tela de mezclilla como una solución preparada de índigo. Después del tratamiento, la mezclilla adquirió un aspecto de usada, sin que las fibras mostraran evidencia de daño, mientras que la solución [...] de índigo se decoloró. Adicionalmente, el análisis de la biodegradación de los desechos acuosos de la decoloración de la mezclilla y la solución decolorada control de índigo mostraron que, en ambos casos el agua residual fue fácilmente biodegradada tanto aeróbica como anaeróbicamente, mientras que la solución control de índigo requirió de 5 días para biodegradarse aeróbicamente y no sufrió ningún cambio en el sistema anaeróbico. El ABTS oxidado ó la lacasa por sí solos no decoloraron la mezclilla ni la solución de índigo bajo las mismas condiciones experimentales en que se empleó la combinación de ambos ABTS-lacasa. Esto se explica porque, durante la reacción de decoloración, el mediador se recicla varias veces entre la enzima y el colorante, de tal forma que en 30 minutos, una molécula de ABTS oxida 800 moléculas de índigo, además la velocidad de decoloración fue dos órdenes de magnitud mayor que la velocidad cuando se empleó el ABTS ó la enzima en forma individual. Abstract in english The ABTS (2,2'-[3-etil benzotiazolin-6-sulphonic]acid)-Laccase system was applied for discoloration of both commercial denim fabric and a synthetic indigo solution. After treatment, the denim fabric looked like an aged one, although fibers did not exhibit any damage and the synthetic indigo solution [...] was bleached. Additionally, an analysis of both the denim discoloration residual water and the synthetic indigo solution biodegradation, showed that in the two cases the residual water was easily biodegraded in either an aerobic or anaerobic mode, while the control indigo solution required 5 days to be biodegraded in an aerobic mode, and it became unaltered in anaerobic mode. The oxidized ABTS or the laccase could not bleach denim or the synthetic indigo solution in the same experimental conditions as when using the system ABTS-laccase. This is explained considering that, during this process, as when using the mediator recycles several times between the laccase and the indigo, in such way that in a 30 min period, one molecule of ABTS oxidized 800 indigo molecules; also, the observed discoloration rate was two orders of magnitude higher than the rates observed when either the oxidized mediator or the enzyme by itself were applied.

  2. Reactions of clofibric acid with oxidative and reductive radicals—Products, mechanisms, efficiency and toxic effects

    International Nuclear Information System (INIS)

    The degradation of clofibric acid induced by hydroxyl radical, hydrated electron and O2??/HO2? reactive species was studied in aqueous solutions. Clofibric acid was decomposed more effectively by hydroxyl radical than by hydrated electron or O2??/HO2?. Various hydroxylated, dechlorinated and fragmentation products have been identified and quantified. A new LC–MS method was developed based on 18O isotope labeling to follow the formation of hydroxylated derivatives of clofibric acid. Possible degradation pathways have been proposed. The overall degradation was monitored by determination of sum parameters like COD, TOC and AOX. It was found that the organic chlorine degrades very effectively prior to complete mineralization. After the treatment no toxic effect was found according to Vibrio fischeri tests. However, at early stages some of the reaction products were more harmful than clofibric acid. - Highlights: • Clofibric acid is effectively degraded by OH radical. • Main primary and secondary products are hydroxylated and dihydroxylated phenyl type derivatives of clofibric acid. • In air saturated aqueous solutions O2 plays an important role in decomposition of the aromatic structure. • A new LC–MS method with 18O-labeling was developed. • Early stage reaction products are more toxic to bacteria Vibrio fischeri than clofibric acid

  3. Radical Scavenging Capacity of Methanolic Phillyrea latifolia L. Extract: Anthocyanin and Phenolic Acids Composition of Fruits

    Directory of Open Access Journals (Sweden)

    Naciye Erkan

    2013-01-01

    Full Text Available Radical scavenging capacity of a crude methanolic extract from the fruits of Phillyrea latifolia L., commonly known as green olive tree or mock privet, was investigated with reference to anthocyanin standards, as flavonoids, and phenolic acid standards, as phenylpropanoids. Characterization with high performance liquid chromatography-diode array detection (HPLC-DAD indicated the presence of keracyanin, kuromanin, cyanidin, ferulic acid, caffeic acid and rosmarinic acid at amounts of 289.1, 90.4, 191.4, 225.2, 221.2 and 190.1 mg/100 g fresh weight (FW of fruits, respectively. Chlorogenic and p-coumaric acids were found to exist in lower amounts. Trolox equivalent antioxidant capacity (TEAC and IC50 values of the plant extract were found to be 1.8 mM Trolox equivalents (TE/g FW of fruits and 69.4 µg/mL, respectively, indicating the close radical scavenging activity of the extract to those of keracyanin and p-coumaric acid. The crude methanolic P. latifolia L. fruit extract was seen to be fairly potent in radical scavenging. Total phenolic content (TPC of the plant extract was found to be 1652.9 mg gallic acid equivalent (GAE/100 g FW of fruits.

  4. 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.

    Science.gov (United States)

    Kadoma, Yoshinori; Fujisawa, Seiichiro

    2008-01-01

    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 (k(inh)/k(p)) 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/ME mixture was approximately 1. The reported beneficial antioxidant, anti-inflammatory and anticancer effects of caffeic acid and p-coumaric acid may be related to their prooxidant-antioxidant balance in the presence of GSH. PMID:18923340

  5. 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/ME mixture was approximately 1. The reported beneficial antioxidant, anti-inflammatory and anticancer effects of caffeic acid and p-coumaric acid may be related to their prooxidant-antioxidant balance in the presence of GSH.

  6. Electron spin resonance and pulse radiolysis studies of the acid-base properties of the m-benzosemiquinone radical anion

    International Nuclear Information System (INIS)

    The 3-hydroxyphenoxyl radical, the conjugate acid of the m-benzosemiquinone radical anion, examined by in situ radiolysis-ESR methods at pH 4.0 exhibits a difference between the hyperfine constants of the protons at the C4 and C6 positions, 11.21 G vs. 8.69 G, respectively. This difference is not manifest in studies in more acidic solutions where the hyperfine constants are averaged as the result of proton exchange. While the total unpaired spin population on the ring is similar to that for phenoxyl radical there is an appreciable shift of spin away from the OH group. In studies of solutions near to neutral, exchange between the acidic and basic forms of the radical is slow and contributions from both the 3-hydroxyphenoxyl radical and the m-benzosemiquinone radical anion are apparent. The pK/sub a/ for acidic dissociation of this radical is found to be 6.43 +/- 0.05 from both ESR and optical absorption studies of the pH dependence of the relative population of its acidic and basic forms. This pK/sub a/ is 3 units below that of the lowest pK/sub a/ of this radical's parent compound, resorcinol. Phosphate can be used to catalyze equilibration so that above 0.1 M phosphate only a single ESR spectrum representing the weighted average of the acidic and basic forms of this radical is observed

  7. Radical chromatography of spin adducts produced from ?-irradiated linoleic acid in nonaqueous solution

    International Nuclear Information System (INIS)

    Spin adducts produced from ?-irradiated linoleic acid in an ethanol solution containing 2-methyl-2-nitrosopropane could be separated into nine fractions with high performance liquid chromatography. Distinct ESR spectra were observed from seven fractions and radical structures were identified for two major components. (author)

  8. On heterogeneity of radical distribution in ?-irradiated monocrystals of malonic acid

    International Nuclear Information System (INIS)

    At 77 K the EPR spectra are investigated of ?-irradiated monocrystals (dose rate of 0.45 Mrad/hr, irradiation dose of 0.9 Mrad) of malonic acid-CH2(COOH)2, CD2(COOD)2 and CH2(COOH)2 with heterogenous addition of CD2(COOD)2 set down on the surface of crystal defects. It is shown that during the radiolysis of malonic acid the initial radicals are formed mainly close to crystal structure defects

  9. Search for oxygen-centered free radicals in the lipoxygenase/linoleic acid system

    International Nuclear Information System (INIS)

    Studies of the oxygenation of linoleic acid by soybean lipoxygenase utilizing electron spin resonance spectroscopy and oxygen uptake have been undertaken. The spin trap, alpha-(4-pyridyl-1-oxide)-N-t-butylnitrone (4-POBN) was included in the lipoxygenase system to capture short-lived free radicals. Correlation of radical adduct formation rates with oxygen uptake studies indicated that the major portion of radical adduct formation occurred when the system was nearly anaerobic. Incubations containing [17O]oxygen with nuclear spin of 5/2 did not have additional ESR lines as would be expected if an oxygen-centered 4-POBN-lipid peroxyl radical adduct were formed indicating that the trapped radical must be reassigned as a carbon-centered species. To establish the presence of [17O2]oxygen in our incubations, a portion of the gas from the lipoxygenase/linoleate experiments was used to prepare the 4-POBN-superoxide radical adduct utilizing a superoxide producing microsomal/paraquat/NADPH system

  10. 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 ?M–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.

  11. Resistance to ABT-737 in activated T lymphocytes: molecular mechanisms and reversibility by inhibition of the calcineurin-NFAT pathway.

    Science.gov (United States)

    Cippà, P E; Kraus, A K; Lindenmeyer, M T; Chen, J; Guimezanes, A; Bardwell, P D; Wekerle, T; Wüthrich, R P; Fehr, T

    2012-01-01

    Dynamic regulation of the intrinsic apoptosis pathway controls central and peripheral lymphocyte deletion, and may interfere with the pro-apoptotic potency of B-cell lymphoma 2 inhibitors such as ABT-737. By following a T-cell receptor (TCR) transgenic population of alloantigen-specific T cells, we found that sensitivity to ABT-737 radically changed during the course of allo-specific immune responses. Particularly, activated T cells were fully resistant to ABT-737 during the first days after antigen recognition. This phenomenon was caused by a TCR-calcineurin-nuclear factor of activated T cells-dependent upregulation of A1, and was therefore prevented by cyclosporine A (CsA). As a result, exposure to ABT-737 after alloantigen recognition induced selection of alloreactive T cells in vivo, whereas in combination with low-dose CsA, ABT-737 efficiently depleted alloreactive T cells in murine host-versus-graft and graft-versus-host models. Thus, ABT-737 resistance is not a prerogative of neoplastic cells, but it physiologically occurs in T cells after antigen recognition. Reversibility of this process by calcineurin inhibitors opens new pharmacological opportunities to modulate this process in the context of cancer, autoimmunity and transplantation. PMID:22513873

  12. Measurement of allantoin and uric acid in human body fluids. A potential index of free-radical reactions in vivo?

    Science.gov (United States)

    Grootveld, M; Halliwell, B

    1987-01-01

    Free-radical attack upon uric acid generates allantoin [Ames, Cathcart, Schwiers & Hochstein (1981) Proc. Natl. Acad. Sci. U.S.A. 78, 6858-6862]. Methods are described for the accurate measurement of uric acid and allantoin in human body fluids. The concentrations of uric acid and allantoin in human serum and synovial fluid are reported. It is suggested that measurement of changes in allantoin concentration may be a useful index of free-radical reactions taking place in vivo. PMID:3663100

  13. 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)

  14. 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

    OpenAIRE

    Seiichiro Fujisawa; Yoshinori Kadoma

    2008-01-01

    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...

  15. Radical scavenging capacity of Agrimonia eupatoria and Agrimonia procera.

    Science.gov (United States)

    Venskutonis, P R; Skemaite, M; Ragazinskiene, O

    2007-02-01

    The antioxidant activity of Agrimonia eupatoria (Agrimony) and Agrimonia procera (Fragrant agrimony) extracts was assessed by measuring in DPPH radical scavenging and ABTS(+) radical decolourisation reaction systems. Radical scavenging capacity of agrimony extracts varied in a wide range (9.1-97.5% in DPPH reaction and 6.7-79.5% in ABTS reaction) depending on the polarity of the solvent used to obtain the extract. PMID:17215090

  16. Adsorption of a carboxylic acid-functionalized aminoxyl radical onto SiO?.

    Science.gov (United States)

    Murata, Hidenori; Baskett, Martha; Nishide, Hiroyuki; Lahti, Paul M

    2014-04-15

    Silicon wafers both without and with silicon(IV) oxide surface coverage were covered with benzene solutions of stable organic radical 3-(N-tert-butyl-N-aminoxyl)benzoic acid (mNBA). X-ray photoelectron spectroscopy supported the presence of the radical on both surface-cleaned (oxide-reduced) and oxide-covered surfaces. Optical waveguide spectroscopy showed that the radical retained its structure while adsorbed to the surface of the wafers, without noticeable decomposition. AFM and MFM imaging showed that the radical formed blocky particles with a change in rms roughness from 0.3 nm premodification to 1.7 nm postmodification on the surface-cleaned silicon. Similar experiments using oxide-coated silicon showed that the radical adsorbed to form much smoother layers, with a small change in rms roughness from 0.2 to 0.3 nm. Contact angle measurements of water on the premodified and postmodified samples showed a large, hydrophobic change in the silicon oxide surface but only a modest change in the surface-cleaned silicon surface. Samples of mNBA adsorbed onto silica gel showed strong electron-spin resonance signals from the aminoxyl spin, even years after production. The results demonstrate the prospects for treating and coating oxide-covered silicon wafers and silicon oxide-coated particles with a paramagnetically active organic substrate, without major chemical modification of the pretreatment surface; the resulting organic spin sites can be stable for years. PMID:24684264

  17. Pyrite-induced hydroxyl radical formation and its effect on nucleic acids

    Directory of Open Access Journals (Sweden)

    Leifer Nicole

    2006-04-01

    Full Text Available Abstract Background Pyrite, the most abundant metal sulphide on Earth, is known to spontaneously form hydrogen peroxide when exposed to water. In this study the hypothesis that pyrite-induced hydrogen peroxide is transformed to hydroxyl radicals is tested. Results Using a combination of electron spin resonance (ESR spin-trapping techniques and scavenging reactions involving nucleic acids, the formation of hydroxyl radicals in pyrite/aqueous suspensions is demonstrated. The addition of EDTA to pyrite slurries inhibits the hydrogen peroxide-to-hydroxyl radical conversion, but does not inhibit the formation of hydrogen peroxide. Given the stability of EDTA chelation with both ferrous and ferric iron, this suggests that the addition of the EDTA prevents the transformation by chelation of dissolved iron species. Conclusion While the exact mechanism or mechanisms of the hydrogen peroxide-to-hydroxyl radical conversion cannot be resolved on the basis of the experiments reported in this study, it is clear that the pyrite surface promotes the reaction. The formation of hydroxyl radicals is significant because they react nearly instantaneously with most organic molecules. This suggests that the presence of pyrite in natural, engineered, or physiological aqueous systems may induce the transformation of a wide range of organic molecules. This finding has implications for the role pyrite may play in aquatic environments and raises the question whether inhalation of pyrite dust contributes to the development of lung diseases.

  18. Towards fuel cell membranes with improved lifetime: Aquivion® Perfluorosulfonic Acid membranes containing immobilized radical scavengers

    Science.gov (United States)

    D'Urso, C.; Oldani, C.; Baglio, V.; Merlo, L.; Aricò, A. S.

    2014-12-01

    A facile synthesis, based on a wet impregnation technique and a thermal treatment, of a novel silica-supported cerium-oxide-based radical scavenger bearing sulfonic acid functionalities is presented. This material is loaded as a filler in ePTFE reinforced membranes (called R79-02S) prepared starting from Aquivion® Perfluoro-Sulfonic Acid (PFSA) dispersions. The aim is to mitigate the peroxy radicals attack to the polymeric membrane under fuel cell operating conditions. These membranes show much longer (7 times more) life-time in Accelerated Stress Tests (AST) and reduced fluoride release (about one half) in Fenton's tests than the radical scavenger-free membrane without any loss in electrochemical performance. Scavenger-free Aquivion® PFSA-based membrane durability is about 200 h in AST whereas the same membrane containing the newly developed radical scavenger exceeds 1400 h. These results confirm the stability of the modified membranes and the excellent activity of the composite scavenger in mitigating the polymer electrolyte degradation.

  19. Products of aqueous vitamin B5 (pantothenic acid) formed by free radical reactions

    International Nuclear Information System (INIS)

    The radiolysis of aqueous vitamin B5 (pantothenic acid) has been investigated under various experimental conditions. The highest vitamin degradation (G=3.22) was observed in solutions saturated with N2O, where 90% OH radicals are operating. As final products, the following were established: aldehydes, carboxylic acids and ammonia. Their yield strongly depends on the presence/absence of air as well as on N2O (used to convert eaq - into OH) and was determined as a function of absorbed radiation dose. HPLC-analysis showed that in all media, a main product is formed, having the highest yield in aerated solutions. Based on the chemical analysis, it appears that the OH radicals are most involved in the degradation process. A precise sequence of the reaction steps could not be given presently, because of the implication of many simultaneous reactions

  20. The reaction of sulfite anion radical (S03sup(.-)) with polyunsaturated fatty acids

    International Nuclear Information System (INIS)

    Using the pulse radiolysis technique, S03sup(.-) was produced in aqueous solution by the reaction of S032-with either sup(.)OH or the (pseudo-) halide radicals N3sup(.),Br2sup(.-), and (SCN)2sup(.-); for the latter reactions rate constants were measured. The reaction of S03sup(.-) with linoleic, linolenic, and arachidonic acids was monitored using the strong absorption of the pentadienyl radical, one possible primary reaction product. In micellar systems no detectable reaction took place, however, monomeric fatty acids were observed to react with S03sup(.-). Lower limits of the rate constants for S03sup(.-) attack derived from the data are 1 x 105, 8 x 105, and 1.3 x 106 (dm3 mol-1 s-1) for linoleate, linolenate, and arachidonate, respectively. (author)

  1. Human red cells scavenge extracellular hydrogen peroxide and inhibit formation of hypochlorous acid and hydroxyl radical.

    OpenAIRE

    Winterbourn, C C; Stern, A.

    1987-01-01

    The ability of intact human red cells to scavenge extracellularly generated H2O2 and O2-, and to prevent formation of hydroxyl radicals and hypochlorous acid has been examined. Red cells inhibited oxidation of ferrocytochrome c by H2O2. Cells treated with aminotriazole no longer inhibited, indicating that protection was almost entirely due to intracellular catalase. Contribution by the GSH system was slight, and apparent only with low H2O2 concentrations when catalase was inhibited by aminotr...

  2. ACID GAS REMOVAL CHARACTERISTICS OF CORONA RADICAL SHOWER SYSTEM FOR A TREATMENT OF STATIONARY ENGINE FLUE GAS

    Science.gov (United States)

    Acid gas removal experiments are carried out in large bench scale corona radical shower reactor. A simulated engine flue gas is air mixed with NO, SO2 and CH4. Optimums for acid gas removal rate have been conducted in terms of the ammonia to acid gas molar ratio, the applied volt...

  3. Antioxidant and Free Radical Scavenging Capacity of Seed and Shell Essential Oils Extracted from Abrus precatorius (L

    Directory of Open Access Journals (Sweden)

    Sunday O. Okoh

    2014-04-01

    Full Text Available Essential oils from plants have been proven safe as natural antioxidants, and few are already marketed as digestive enhancers as well as in prevention of several degenerative diseases. This study evaluated the antioxidant capacity of seed and shell essential oils of Abrus precatorius (L, a herb used for ethno-medicinal practices in Nigeria. The essential oils were obtained by hydro-distillation. The ability of the oils to act as hydrogen/electrons donor or scavenger of radicals were determined by in-vitro antioxidant assays using 2,2-diphenyl-2-picryl-hydrazyl free radical (DPPH. scavenging; 2,2?-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS radical scavenging; lipid peroxide and nitric oxide radicals scavenging assays. The IC50 of the seed and shell oils (2.10 mg/mL and 1.20 mg/mL respectively showed that antioxidant activity is higher than that for the standard drugs (3.20 mg/mL and 3.40 mg/mL for the nitric oxide scavenging assay. The lipid peroxidation radical activity of the oils were similar to vitamin C, weak DPPH and ABTS radical scavenging activities were discovered in comparison to vitamin C and rutin. Generally, in the four antioxidant assays, a significant correlation existed between concentrations of the oils and percentage inhibition of free radicals and lipid peroxidation. The composition of A. precatorius essential oils reported earlier may account for their antioxidant capacity.

  4. Comparative evaluation of free radical scavenging activity of Boerhaavia diffusa root extracts (BDRE) and determination of dose effectivity against radiation induced damages in Swiss albino mice

    OpenAIRE

    SHARMA, J; Saini, M. R.; P Dhakar

    2012-01-01

    Summary: Purpose of the study was to evaluate free radical scavenging activity (FRSA) of root extracts of Boerhaavia diffusa in different solvents and to examine its dose effectivity against radiation induced damages in Swiss albino mice. Scavenging activities of aqueous, ethanolic and hydroethanolic extracts of B. diffusa roots were evaluated by DPPH (2, 2-diphenyl-1 picryl hydrazyl), ABTS (2,2’-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid) and NO (nitric oxide) assay to find the most...

  5. The B-cell lymphoma 2 (BCL2)-inhibitors, ABT-737 and ABT-263, are substrates for P-glycoprotein

    International Nuclear Information System (INIS)

    Highlights: ? The BCL2-inhibitor ABT-263 is a substrate for P-glycoprotein. ? Apoptosis is inhibited by P-glycoprotein expression. ? Overexpression of P-glycoprotein may contribute to resistance to ABT-263 or ABT-737. -- Abstract: Inhibition of BCL2 proteins is one of the most promising new approaches to targeted cancer therapy resulting in the induction of apoptosis. Amongst the most specific BCL2-inhibitors identified are ABT-737 and ABT-263. However, targeted therapy is often only effective for a limited amount of time because of the occurrence of drug resistance. In this study, the interaction of BCL2-inhibitors with the drug efflux transporter P-glycoprotein was investigated. Using 3H labelled ABT-263, we found that cells with high P-glycoprotein activity accumulated less drug. In addition, cells with increased P-glycoprotein expression were more resistant to apoptosis induced by either ABT-737 or ABT-263. Addition of tariquidar or verapamil sensitized the cells to BCL2-inhibitor treatment, resulting in higher apoptosis. Our data suggest that the BCL2-inhibitors ABT-737 and ABT-263 are substrates for P-glycoprotein. Over-expression of P-glycoprotein may be, at least partly, responsible for resistance to these BCL2-inhibitors.

  6. Reaction of single-standard DNA with hydroxyl radical generated by iron(II)-ethylenediaminetetraacetic acid

    International Nuclear Information System (INIS)

    This study demonstrates that the reaction of Fe(II)-EDTA and hydrogen peroxide with the single-stranded nucleic acids d(pT)70 and a 29-base sequence containing a mixture of bases results in substantial damage which is not directly detected by gel electrophoresis. Cleavage of the DNA sugar backbone is enhanced significantly after the samples are incubated at 90 degree C in the presence of piperidine. The latter reaction is used in traditional Maxam-Gilbert DNA sequencing to detect base damage, and the current results are consistent with reaction of the hydroxyl radical with the bases in single-stranded DNA (although reaction with sugar may also produce adducts that are uncleaved but labile to cleavage by piperidine). We the authors propose that hydroxyl radicals may react preferentially with the nucleic acid bases in ssDNA and that reaction of the sugars in dsDNA is dominant because the bases are sequestered within the double helix. These results have implications both for the study of single-stranded DNA binding protein binding sites and for the interpretation of experiments using the hydroxyl radical to probe DNA structure or to footprint double-stranded DNA binding protein binding sites

  7. Reaction of sulphate radical anion (SO4·-) with cyanuric acid. A potential reaction for its degradation?

    International Nuclear Information System (INIS)

    A novel reaction between sulfate radical anion (SO4·-) and cyanuric acid (CA), a non-degradable end product of the oxidative degradation of the triazine based herbicide, atrazine, is presented using laser flash photolysis and steady state radiolysis techniques at pH 5. A second order rate constant of 1.9x107 dm3 mol-1 s-1 has been determined and the transient intermediate (?max=330 nm) is assigned to a radical cation of CA (CA·+). The degradation profile indicated that about 76% of CA have been decomposed after an absorbed ?-radiation dose of 18 kGy. It is therefore proposed that the reaction of SO4·- could be utilised for the degradation of CA in aqueous medium which is normally stable to any Advanced Oxidation Processes. (author)

  8. Characterization of fatty acids, bioactive lipids, and radical scavenging activity of Canterbury bells seed oil

    Directory of Open Access Journals (Sweden)

    Hassanien, M. F.R.

    2014-06-01

    Full Text Available The aim of this study was to characterize the chemical composition and radical scavenging activity of Canterbury bells (Campanula medium seed oil. C. medium seeds contained 9.2% extractable oil. The lipid classes, fatty acids, phytosterol and tocopherol composition of C. medium seed oil were determined. The amount of neutral lipids in the oil was the highest, followed by glycolipids and phospholipids. Linoleic and oleic were the main fatty acids. C. medium oil is characterized by high levels of phytosterols and ?-sitosterol was the main compound. ?-Tocopherol constituted 42.5% of the total tocopherol content followed by ?-tocopherol. The radical scavenging activity (RSA toward 1,1-diphenyl-2-picrylhydrazyl (DPPH radicals and galvinoxyl radicals of C. medium oil were higher than those of extra virgin olive oil. The diverse potential uses of C. medium oil may make this plant industrially important.El objetivo de este estudio fue caracterizar la composición química y la actividad de captación de radicales de aceites de semillas de campanillas de Canterbury (Campanula medium. Las semillas de C. medium contenían 9,2 % de aceite extraíble. Se determinó la composición de las diferentes clases de lípidos, ácidos grasos, fitoesteroles y tocoferoles. La cantidad de lípidos neutros en el aceite fue mayoritario, seguido de glicolípidos y fosfolípidos. Linoleico y oleico fueron los ácidos grasos principales. El aceite de C. medium se caracteriza por altos niveles de fitoesteroles y ?-sitosterol fue el compuesto principal. ?-tocoferol constituía 42,5 % del contenido total de tocoferol seguido de ?-tocoferol. La actividad de captación de radicales (RSA a 1,1-difenil-2- picrilhidrazil (DPPH y radicales galvinoxil de C. medium fueron superiores a las de aceite de oliva virgen extra. Los diversos usos potenciales de los aceites de C. medium pueden hacer que esta planta pueda ser importante industrialmente.

  9. Isolation and characterisation of in vitro and cellular free radical scavenging peptides from corn peptide fractions.

    Science.gov (United States)

    Wang, Liying; Ding, Long; Wang, Ying; Zhang, Yan; Liu, Jingbo

    2015-01-01

    Corn gluten meal, a corn processing industry by-product, is a good source for the preparation of bioactive peptides due to its special amino acid composition. In the present study, the in vitro and cellular free radical scavenging activities of corn peptide fractions (CPFs) were investigated. Results indicated that CPF1 (molecular weight less than 1 kDa) and CPF2 (molecular weight between 1 and 3 kDa) exhibited good hydroxyl radical, superoxide anion radical and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonicacid) diammonium salt (ABTS) radical scavenging activity and oxygen radical absorbance capacity (ORAC). Meanwhile, the in vitro radical scavenging activity of CPF1 was slightly higher than that of CPF2. Both CPF1 and CPF2 also exhibited significant cytoprotective effects and intracellular reactive oxygen species scavenging activity in Caco-2 cells exposed to hydrogen peroxide (H2O2). The amino acid composition analysis revealed that the CPF were rich in hydrophobic amino acids, which comprised of more than 45% of total amino acids. An antioxidant peptide sequence of Tyr-Phe-Cys-Leu-Thr (YFCLT) was identified from CPF1 using matrix-assisted laser desorption/ionization time-of-flight/time-of-?ight mass spectrometry (MALDI TOF/TOF MS). The YFCLT exhibited excellent ABTS radical scavenging activity with a 50% effective concentration (EC50) value of 37.63 µM, which was much lower than that of Trolox. In conclusion, corn gluten meal might be a good source to prepare antioxidant peptides. PMID:25690286

  10. Isolation and Characterisation of in Vitro and Cellular Free Radical Scavenging Peptides from Corn Peptide Fractions

    Directory of Open Access Journals (Sweden)

    Liying Wang

    2015-02-01

    Full Text Available Corn gluten meal, a corn processing industry by-product, is a good source for the preparation of bioactive peptides due to its special amino acid composition. In the present study, the in vitro and cellular free radical scavenging activities of corn peptide fractions (CPFs were investigated. Results indicated that CPF1 (molecular weight less than 1 kDa and CPF2 (molecular weight between 1 and 3 kDa exhibited good hydroxyl radical, superoxide anion radical and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonicacid diammonium salt (ABTS radical scavenging activity and oxygen radical absorbance capacity (ORAC. Meanwhile, the in vitro radical scavenging activity of CPF1 was slightly higher than that of CPF2. Both CPF1 and CPF2 also exhibited significant cytoprotective effects and intracellular reactive oxygen species scavenging activity in Caco-2 cells exposed to hydrogen peroxide (H2O2. The amino acid composition analysis revealed that the CPF were rich in hydrophobic amino acids, which comprised of more than 45% of total amino acids. An antioxidant peptide sequence of Tyr-Phe-Cys-Leu-Thr (YFCLT was identified from CPF1 using matrix-assisted laser desorption/ionization time-of-flight/time-of-?ight mass spectrometry (MALDI TOF/TOF MS. The YFCLT exhibited excellent ABTS radical scavenging activity with a 50% effective concentration (EC50 value of 37.63 µM, which was much lower than that of Trolox. In conclusion, corn gluten meal might be a good source to prepare antioxidant peptides.

  11. Reactivity of chlorine radical with submicron palmitic acid particles: kinetic measurements and products identification

    OpenAIRE

    Mendez, M; R. Ciuraru; S. Gosselin; Batut, S.; N. Visez; D. Petitprez

    2013-01-01

    The heterogeneous reaction of Cl. radicals with sub-micron palmitic acid (PA) particles was studied in an aerosol flow tube in the presence or in the absence of O2. Fine particles were generated by homogeneous condensation of PA vapors and introduced in the reactor where chlorine atoms are produced by photolysis of Cl2 using UV lamps surrounding the reactor. The effective reactive uptake coefficient (?) has been determined from the rate loss of PA measured by GC/MS analysis of reacted p...

  12. Reactivity of chlorine radical with submicron palmitic acid particles: kinetic measurements and product identification

    Science.gov (United States)

    Mendez, M.; Ciuraru, R.; Gosselin, S.; Batut, S.; Visez, N.; Petitprez, D.

    2013-12-01

    The heterogeneous reaction of Cl• radicals with submicron palmitic acid (PA) particles was studied in an aerosol flow tube in the presence or in the absence of O2. Fine particles were generated by homogeneous condensation of PA vapours and introduced into the reactor, where chlorine atoms were produced by photolysis of Cl2 using UV lamps surrounding the reactor. The effective reactive uptake coefficient (?) has been determined from the rate loss of PA measured by gas chromatography-mass spectrometer (GC/MS) analysis of reacted particles as a function of the chlorine exposure. In the absence of O2, ? = 14 ± 5 indicates efficient secondary chemistry involving Cl2. GC/MS analysis has shown the formation of monochlorinated and polychlorinated compounds in the oxidized particles. Although the PA particles are solid, the complete mass can be consumed. In the presence of oxygen, the reaction is still dominated by secondary chemistry but the propagation chain length is smaller than in the absence of O2, which leads to an uptake coefficient ? = 3 ± 1. In the particulate phase, oxocarboxylic acids and dicarboxylic acids were identified by GC/MS. The formation of alcohols and monocarboxylic acids is also suspected. A reaction pathway for the main products and more functionalized species is proposed. All these results show that solid organic particles could be efficiently oxidized by gas-phase radicals not only on their surface but also in bulk by mechanisms which are still unclear. They help to understand the aging of primary tropospheric aerosol containing fatty acids.

  13. Reactivity of chlorine radical with submicron palmitic acid particles: kinetic measurements and products identification

    Science.gov (United States)

    Mendez, M.; Ciuraru, R.; Gosselin, S.; Batut, S.; Visez, N.; Petitprez, D.

    2013-06-01

    The heterogeneous reaction of Cl. radicals with sub-micron palmitic acid (PA) particles was studied in an aerosol flow tube in the presence or in the absence of O2. Fine particles were generated by homogeneous condensation of PA vapors and introduced in the reactor where chlorine atoms are produced by photolysis of Cl2 using UV lamps surrounding the reactor. The effective reactive uptake coefficient (?) has been determined from the rate loss of PA measured by GC/MS analysis of reacted particles as a function of the chlorine exposure. In the absence of O2, ? = 14 ± 5 indicates efficient secondary chemistry involving Cl2. GC/MS analyses have shown the formation of monochlorinated and polychlorinated compounds in the oxidized particles. Although, the PA particles are solid, the complete mass can be consumed. In the presence of oxygen, the reaction is still dominated by secondary chemistry but the propagation chain length is smaller than in the absence of O2 which leads to an uptake coefficient ? = 3 ± 1. In the particulate phase, oxocarboxylic acids and dicarboxylic acids are identified by GC/MS. Formation of alcohols and monocarboxylic acids are also suspected. All these results show that solid organic particles could be efficiently oxidized by gas-phase radicals not only on their surface, but also in bulk by mechanisms which are still unclear. Furthermore the identified reaction products are explained by a chemical mechanism showing the pathway of the formation of more functionalized products. They help to understand the aging of primary tropospheric aerosol containing fatty acids.

  14. Reactivity of chlorine radical with submicron palmitic acid particles: kinetic measurements and products identification

    Directory of Open Access Journals (Sweden)

    M. Mendez

    2013-06-01

    Full Text Available The heterogeneous reaction of Cl. radicals with sub-micron palmitic acid (PA particles was studied in an aerosol flow tube in the presence or in the absence of O2. Fine particles were generated by homogeneous condensation of PA vapors and introduced in the reactor where chlorine atoms are produced by photolysis of Cl2 using UV lamps surrounding the reactor. The effective reactive uptake coefficient (? has been determined from the rate loss of PA measured by GC/MS analysis of reacted particles as a function of the chlorine exposure. In the absence of O2, ? = 14 ± 5 indicates efficient secondary chemistry involving Cl2. GC/MS analyses have shown the formation of monochlorinated and polychlorinated compounds in the oxidized particles. Although, the PA particles are solid, the complete mass can be consumed. In the presence of oxygen, the reaction is still dominated by secondary chemistry but the propagation chain length is smaller than in the absence of O2 which leads to an uptake coefficient ? = 3 ± 1. In the particulate phase, oxocarboxylic acids and dicarboxylic acids are identified by GC/MS. Formation of alcohols and monocarboxylic acids are also suspected. All these results show that solid organic particles could be efficiently oxidized by gas-phase radicals not only on their surface, but also in bulk by mechanisms which are still unclear. Furthermore the identified reaction products are explained by a chemical mechanism showing the pathway of the formation of more functionalized products. They help to understand the aging of primary tropospheric aerosol containing fatty acids.

  15. Oxidation of Amino Acids by Chlorpromazine Cation Radical and Co-Catalysis by Chlorpromazine

    Directory of Open Access Journals (Sweden)

    Manoel L. de Menezes

    2012-01-01

    Full Text Available The long-tem use of chlorpromazine (CPZ may cause severe side effects. This property of CPZ might be related to pro-oxidant effects of the chlorpromazine cation radical (CPZ·+, which can be easily generated by catalytic action of peroxidases, including the neutrophil myeloperoxidase (MPO and by methemoglobin. Aiming the comprehension of a putative physiological effect of CPZ·+ upon biomolecules, in this work we studied the reactivity of CPZ·+ with amino acids and the co-catalytic effect of CPZ during the oxidation of amino acids by horseradish peroxidase (HRP/H2O2 system. We also studied whether natural blood plasma components as ascorbic acid, uric acid and nitrite could inhibit the oxidative effect of CPZ·+. We found that tryptophan, tyrosine and cysteine were easily oxidized by pure CPZ·+. Other amino acids as methionine, glycine, phenylalanine, aspartic acid and lysine were unreactive. The decomposition of CPZ·+ was exacerbated by uric acid, ascorbic acid and nitrite, provoking inhibition in the amino acids oxidation. In experiments with HRP/H2O2, and using CPZ as a co-catalyst, a strong effect upon oxidation of tryptophan, tyrosine and cysteine was obtained. It was also found that tryptophan was more reactive than tyrosine with CPZ·+, a feature that could be related to the recently described favorable interaction between tryptophan and CPZ. The use of CPZ as a co-catalyst is discussed regarding its role in the efficient oxidation of tryptophan.

  16. Electrospray ionization mass spectrometry applied to study the radical acetylation of amino acids, peptides and proteins

    Scientific Electronic Library Online (English)

    Atecla N. L., Alves; Leticia D. L., Jedlicka; Júlio, Massari; Maria A., Juliano; Etelvino J. H., Bechara; Nilson A., Assunção.

    1983-19-01

    Full Text Available Recentemente nosso grupo demostrou experimentalmente que a hipótese de produção de radical acetil em meio tamponado no sistema diacetil/peroxinitrito era possível. Diacetil é um flavorizante em alimentos, cigarros e bebidas. O peroxinitrito é encontrado na mitocôndria, e em certas condições como um [...] processo de infeção em humanos, a concentração aumenta significativamente. Em sistemas biológicos, radicais podem facilmente modificar a estrutura e atividade de ácidos nucleicos, proteínas e outras biomoléculas, causando significativo estres oxidativo. Baseado em dados de ressonância magnética e espectrometria de massas, este artigo apresenta os produtos que provam a produção do radical acetil e a formação de compostos estáveis devido à ligação covalente entre o acetil e os aminoácidos (produtos acetilados), e os adutos de peptídeos e proteínas. Estes materiais foram separados por eletroforese capilar e identificados por espectrometria de massas. O meio reacional consistiu da mistura de diacetil e peroxynitrito em uma relação de 1:2 e em 20 mmol L-1 de fosfato de sódio, no valor de pH 7,2. Estes experimentos também revelam a dupla acetilação da lisina, demonstrando a alta reatividade do composto com biomoléculas contendo grupos de nitrogênio, abundantemente encontradas em sistemas biológicos. A mudança estrutural de uma molécula acetilada é uma fonte de modificações pós-tradução com inúmeras consequências biológicas. Abstract in english Recently, our group proposed a process that generated acetyl radicals in a reaction medium buffered with a diacetyl/peroxynitrite system. Diacetyl is a flavoring agent in food, cigarettes and drinks. Peroxynitrite is found in mitochondria, and in certain conditions, such as an infection in humans, i [...] ts concentration is augmented significantly. In biological systems, radical compounds can easily modify the structure and activity of nucleic acids, proteins and other biomolecules, causing significant oxidative stress. Based on paramagnetic resonance and mass spectrometry data, this work discusses products that prove acetyl radicals are produced and are able to form stable covalent bonds with amino acid (acetylated products), peptide and protein adducts. These materials were separated and detected by capillary electrophoresis coupled with tandem mass spectrometry or offline mass spectrometry. The reaction medium contained a 1:2 mixture of diacetyl and peroxynitrite dissolved in 200 mmol L-1 of pH 7.2 sodium phosphate buffer. These experiments also reveal the double acetylation of lysine, demonstrating the high reactivity of these compounds when in contact with nitrogen-containing biomolecules readily found in biological systems. These structural changes might be an epigenetic source of post-translational protein modification.

  17. Reactions of thiyl radicals with phenothiazines and other antioxidants in aqueous solutions

    International Nuclear Information System (INIS)

    Reaction rate constants of thiyl radicals with phenothiazines, promethazine (PMZ), chlorpromazine (CPZ), prochlorperazine (PPZ), trimeperazine tarterate (TPZ), and other antioxidants, e.g., ascorbic acid and 2.2-azinobis(3-ethyl benzthiazoline-6 sulphonate) (ABTS) have been estimated using pulse radiolysis technique. In general they are quite high (108-109 M-1 s-1). The k values for cysteine, cysteamine, mercaptoethanol, and mercaptopropionic acid with similar structures and molecular weights are more or less similar for PMZ, CPZ, and PPZ. Rate constants are lower in value for PenS, DTT, DTE and GuS radicals of phenothiazines showing that they are dependent upon the structure and the molecular weight of the compound. Rate constants are the same whether the thiyl radicals are generated from thiols or their corresponding disulphides. The k values for chlorine-containing phenothiazines, chlorpromazine, and prochlorperazine are higher than those of promothazine

  18. Antioxidant Activity of Caffeic Acid against Iron-Induced Free Radical Generation—A Chemical Approach

    Science.gov (United States)

    Genaro-Mattos, Thiago C.; Maurício, Ângelo Q.; Rettori, Daniel; Alonso, Antonio; Hermes-Lima, Marcelo

    2015-01-01

    Caffeic acid (CA) is a phenolic compound widely found in coffee beans with known beneficial effects in vivo. Many studies showed that CA has anti-inflammatory, anti-mutagenic, antibacterial and anti-carcinogenic properties, which could be linked to its antioxidant activity. Taking in consideration the reported in vitro antioxidant mechanism of other polyphenols, our working hypothesis was that the CA antioxidant activity could be related to its metal-chelating property. With that in mind, we sought to investigate the chemical antioxidant mechanism of CA against in vitro iron-induced oxidative damage under different assay conditions. CA was able to prevent hydroxyl radical formation promoted by the classical Fenton reaction, as determined by 2-deoxyribose (2-DR) oxidative degradation and DMPO hydroxylation. In addition to its ability to prevent hydroxyl radical formation, CA had a great inhibition of membrane lipid peroxidation. In the lipid peroxidation assays CA acted as both metal-chelator and as hydrogen donor, preventing the deleterious action promoted by lipid-derived peroxyl and alkoxyl radicals. Our results indicate that the observed antioxidant effects were mostly due to the formation of iron-CA complexes, which are able to prevent 2-DR oxidation and DMPO hydroxylation. Noteworthy, the formation of iron-CA complexes and prevention of oxidative damage was directly related to the pH of the medium, showing better antioxidant activity at higher pH values. Moreover, in the presence of lipid membranes the antioxidant potency of CA was much higher, indicating its enhanced effectiveness in a hydrophobic environment. Overall, our results show that CA acts as an antioxidant through an iron chelating mechanism, preventing the formation of free hydroxyl radicals and, therefore, inhibiting Fenton-induced oxidative damage. The chemical properties of CA described here—in association with its reported signaling effects—could be an explanation to its beneficial effects observed in vivo. PMID:26098639

  19. Degradation of hyaluronic acid, poly- and monosaccharides, and model compounds by hypochlorite : evidence for radical intermediates and fragmentation

    DEFF Research Database (Denmark)

    Hawkins, C L; Davies, Michael Jonathan

    1998-01-01

    Degradation of hyaluronic acid by oxidants such as HO. and HOCl/CIO- is believed to be important in the progression of rheumatoid arthritis. While reaction of hyaluronic acid with HO. has been investigated extensively, reaction with HOCl/ClO- is less well defined. Thus, little is known about the site(s) of HOCl/ClO- attack, the intermediates formed, or the mechanism(s) of polymer degradation. In this study reaction of HOCl/ClO- with amides, sugars, polysaccharides, and hyaluronic acid has been monitored by UV-visible (220-340 nm) and EPR spectroscopy. UV-visible experiments have shown that HOCl/ClO- reacts preferentially with N-acetyl groups. This reaction is believed to give rise to transient chloramide (R-NCl-C(O)-R') species, which decompose rapidly to give radicals via either homolysis (to produce N. and Cl.) or heterolysis (one-electron reduction, to give N. and Cl.) of the N--C bond. The nature of the radicals formed has been investigated by EPR spin trapping. Reaction of HOCl/ClO- with hyaluronic acid,chondroitin sulphates A and C, N-acetyl sugars, and amides gave novel, carbon-centered, spin adducts, the formation of which is consistent with selective initial attack at the N-acetyl group. Thus, reaction with hyaluronic acid and chondroitin sulphate A, appears to be localized at the N-acetylglucosamine sugar rings. These carbon-centered radicals are suggested to arise from rapid rearrangement of initial nitrogen-centered radicals, formed from the N-acetyl chloramide, by reactions analogous to those observed with alkoxyl radicals. The detection of increasing yields of low-molecular-weight radical adducts from hyaluronic acid and chondroitin sulphate A with increasing HOCl/ClO-concentrations suggests that formation of the initial nitrogen-centered species on the N-acetylglucosamine rings, and the carbon-centered radicals derived from them, brings about polymer fragmentation.

  20. A Perspective on Free Radical Autoxidation: The Physical Organic Chemistry of Polyunsaturated Fatty Acid and Sterol Peroxidation

    OpenAIRE

    Porter, Ned A.

    2013-01-01

    This Perspective describes advances from the author’s laboratory on the free radical reactions of organic compounds with molecular oxygen. Polyunsaturated fatty acids (PUFAs) and sterols are particularly prone to undergo radical chain oxidation and evidence suggests that this process, known as lipid peroxidation, occurs in vivo under a variety of conditions that are the result of an oxidative stress. Cyclic peroxides, hydroperoxides, and epoxy-alcohols are major products formed from peroxid...

  1. Lipoxygenase-mediated pro-radical effect of melatonin via stimulation of arachidonic acid metabolism

    International Nuclear Information System (INIS)

    We have shown that melatonin immediately and transiently stimulates intracellular free radical production on a set of leukocytes, possibly as a consequence of calmodulin binding. We show here that melatonin-induced ROS are produced by lipoxygenase (LOX), since they are prevented by a set of LOX inhibitors, and are accompanied by increase of the 5-LOX product 5-HETE. LOX activation is accompanied by strong liberation of AA; inhibition of Ca2+-independent, but not Ca2+-dependent, phospholipase A2 (PLA2), prevents both melatonin-induced arachidonic acid and ROS production, whereas LOX inhibition only prevents ROS, indicating that PLA2 is upstream with respect to LOX, as occurs in many signaling pathways. Chlorpromazine, an inhibitor of melatonin-calmodulin interaction, inhibits both ROS and arachidonic acid production, thus possibly placing calmodulin at the origin of a melatonin-induced pro-radical pathway. Interestingly, it is known that Ca2+-independent PLA2 binds to calmodulin: our results are compatible with PLA2 being liberated by melatonin from a steady-state calmodulin sequestration, thus initiating an arachidonate signal transduction. These results delineate a novel molecular pathway through which melatonin may participate to the inflammatory response.

  2. The influence of repulsive electrostatic forces on the lifetimes of poly(acrylic acid) radicals in aqueous solution

    International Nuclear Information System (INIS)

    Poly(acrylic acid) derived carbon-centered radicals were generated either radiolytically or photolytically in deoxygenated aqueous solutions and their decay observed by photometry or EPR. Reaction kinetics strongly depends on electrostatic forces as proved during studies of pH function. The electrostatic forces influences also the rate of intermolecular H-abstraction reactions. Half-lifes of corresponding peroxyl radicals, although also strongly influenced by degree of dissociation of polyelectrolyte, do not reach such high enhancement values. This is interpreted as being due to longer encounter distance in the case of peroxyl radicals. (author)

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

    Directory of Open Access Journals (Sweden)

    Y. Tan

    2011-06-01

    Full Text Available Previous experiments have demonstrated that the aqueous OH radical oxidation of methylglyoxal produces low volatility products including 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 is an important intermediate in aqueous methylglyoxal oxidation and a ubiquitous product of gas phase photochemistry, making it a potential "aqueous" SOA precursor in its own right. Altieri et al. (2008 proposed that acetic acid was the precursor of oligoesters observed in methylglyoxal oxidation. However, the fate of acetic acid upon aqueous-phase oxidation is not well understood. In this research, acetic acid at concentrations relevant to atmospheric waters (20 ?M–10 mM was oxidized by OH radical. Products were analyzed by ion chromatography (IC, electrospray ionization mass spectrometry (ESI-MS, and IC-ESI-MS. The formation of glyoxylic, glycolic, and oxalic acids were observed. In contrast to methylglyoxal oxidation, succinic acid and oligomers were not detected. Using results from these and methylglyoxal + OH radical 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.

  4. Free radical scavenging activity of ethanolic extracts from herbs and spices commercialized in Brazil

    Scientific Electronic Library Online (English)

    Lilian Regina Barros, Mariutti; Gisela Pizarro de Mattos, Barreto; Neura, Bragagnolo; Adriana Zerlotti, Mercadante.

    1225-12-01

    Full Text Available Extratos etanólicos de 23 ervas e condimentos desidratados comercializados no Brasil foram analisados quanto as suas propriedades antioxidantes utilizando os radicais 2,2'-difenil-?-picrilhidrazil (DPPH•) e ácido 2,2'-azino-bis(3-etilbenzotiazolina-6-sulfônico) (ABTS•+), Trolox foi usado como referê [...] ncia para ambos radicais. As curvas cinéticas seguiram o modelo cinético de primeira ordem, e a partir destas foram calculadas as constantes de velocidade de (k obs). Os extratos de sálvia e de alecrim apresentaram as maiores capacidades redutoras de radicais livres, enquanto o extrato de cebola praticamente não apresentou atividade e o colorífico, um dos condimentos mais consumidos no Brasil, apresentou baixa atividade de aprisionamento de radicaisABTS•+. Três situações distintas foram observadas em relação à capacidade de aprisionar radicais DPPH•: (1) extratos, como os de alecrim e de louro, que apresentaram as mesmas concentrações eficientes (EC50), porém, valores de TEAC e velocidade de ação (k obs) distintos ; (2) extratos, como os de alho e de manjericão, que apresentaram valores similares de EC50 e TEAC, com valores distintos de k obs e (3) extratos com a mesma velocidade de ação que diferiram totalmente na capacidade de aprisionamento de radicais livres, como de pimenta preta, segurelha, noz moscada, alecrim e sálvia. Considerações semelhantes podem ser feitas para os resultados de ABTS•+. Osdois métodos apresentaram boa correlação de TEAC, indicando que a reatividade dos compostos presentes nos extratos etanólicos foi similar. A atividade redutora de ABTS•+ para pimenta da Jamaica, manjericão, cardamomo, cebolinha, colorífico, cominho, dill, louro, manjerona, salsinha e estragão foi reportada pela primeira vez. Abstract in english Ethanolic extracts from 23 different dried herbs and spices commercialized in Brazil were investigated for their free radical scavenging properties using the stable free radicals 2,2'-diphenyl-?-picrylhydrazyl (DPPH•) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS•+), and Trolox a [...] s reference (TEAC) for both radicals. The kinetic curves for both radicals showed to follow the first order kinetics model and the decay rate constant (k obs) was calculated. For all the samples, the two methods showed a good linear TEAC correlation, indicating that the average reactivity of the compounds present in the ethanolic extracts was similar. Sage and rosemary extracts showed the highest free radical scavenging capacities, while onion showed negligible activity and colorifico, one of the most consumed spices in Brazil, showed low ABTS•+ scavenging activity. Three distinct situations were found for the extracts concerning the DPPH• scavenging capacities: (1) extracts, like rosemary and laurel, that presented the same efficient concentrations (EC50 ) but differed in the TEAC values and velocities of action (k obs), (2) extracts, such as garlic and basil, that showed similar EC50 and TEAC values, but different k obs values and (3) extracts that reacted at the same velocities but completely differed in the free radical scavenging capacities, like black pepper, savory, nutmeg, rosemary and sage. Similar considerations could be done for the ABTS•+ results. For the first time the ABTS•+ scavenging activity for allspice, basil, cardamom, chives, colorifico, cumin, dill, laurel, marjoram, parsley and tarragon was reported.

  5. Free radical scavenging activity of ethanolic extracts from herbs and spices commercialized in Brazil

    Directory of Open Access Journals (Sweden)

    Lilian Regina Barros Mariutti

    2008-12-01

    Full Text Available Ethanolic extracts from 23 different dried herbs and spices commercialized in Brazil were investigated for their free radical scavenging properties using the stable free radicals 2,2'-diphenyl-?-picrylhydrazyl (DPPH• and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS•+, and Trolox as reference (TEAC for both radicals. The kinetic curves for both radicals showed to follow the first order kinetics model and the decay rate constant (k obs was calculated. For all the samples, the two methods showed a good linear TEAC correlation, indicating that the average reactivity of the compounds present in the ethanolic extracts was similar. Sage and rosemary extracts showed the highest free radical scavenging capacities, while onion showed negligible activity and colorifico, one of the most consumed spices in Brazil, showed low ABTS•+ scavenging activity. Three distinct situations were found for the extracts concerning the DPPH• scavenging capacities: (1 extracts, like rosemary and laurel, that presented the same efficient concentrations (EC50 but differed in the TEAC values and velocities of action (k obs, (2 extracts, such as garlic and basil, that showed similar EC50 and TEAC values, but different k obs values and (3 extracts that reacted at the same velocities but completely differed in the free radical scavenging capacities, like black pepper, savory, nutmeg, rosemary and sage. Similar considerations could be done for the ABTS•+ results. For the first time the ABTS•+ scavenging activity for allspice, basil, cardamom, chives, colorifico, cumin, dill, laurel, marjoram, parsley and tarragon was reported.Extratos etanólicos de 23 ervas e condimentos desidratados comercializados no Brasil foram analisados quanto as suas propriedades antioxidantes utilizando os radicais 2,2'-difenil-?-picrilhidrazil (DPPH• e ácido 2,2'-azino-bis(3-etilbenzotiazolina-6-sulfônico (ABTS•+, Trolox foi usado como referência para ambos radicais. As curvas cinéticas seguiram o modelo cinético de primeira ordem, e a partir destas foram calculadas as constantes de velocidade de (k obs. Os extratos de sálvia e de alecrim apresentaram as maiores capacidades redutoras de radicais livres, enquanto o extrato de cebola praticamente não apresentou atividade e o colorífico, um dos condimentos mais consumidos no Brasil, apresentou baixa atividade de aprisionamento de radicaisABTS•+. Três situações distintas foram observadas em relação à capacidade de aprisionar radicais DPPH•: (1 extratos, como os de alecrim e de louro, que apresentaram as mesmas concentrações eficientes (EC50, porém, valores de TEAC e velocidade de ação (k obs distintos ; (2 extratos, como os de alho e de manjericão, que apresentaram valores similares de EC50 e TEAC, com valores distintos de k obs e (3 extratos com a mesma velocidade de ação que diferiram totalmente na capacidade de aprisionamento de radicais livres, como de pimenta preta, segurelha, noz moscada, alecrim e sálvia. Considerações semelhantes podem ser feitas para os resultados de ABTS•+. Osdois métodos apresentaram boa correlação de TEAC, indicando que a reatividade dos compostos presentes nos extratos etanólicos foi similar. A atividade redutora de ABTS•+ para pimenta da Jamaica, manjericão, cardamomo, cebolinha, colorífico, cominho, dill, louro, manjerona, salsinha e estragão foi reportada pela primeira vez.

  6. A perspective on free radical autoxidation: the physical organic chemistry of polyunsaturated fatty acid and sterol peroxidation.

    Science.gov (United States)

    Porter, Ned A

    2013-04-19

    This Perspective describes advances from the author's laboratory on the free radical reactions of organic compounds with molecular oxygen. Polyunsaturated fatty acids (PUFAs) and sterols are particularly prone to undergo radical chain oxidation, and evidence suggests that this process, known as lipid peroxidation, occurs in vivo under a variety of conditions that are the result of an oxidative stress. Cyclic peroxides, hydroperoxides, and epoxy alcohols are major products formed from peroxidation, and the basic mechanisms of product formation are now reasonably well understood. These mechanisms include reversible addition of oxygen to carbon radicals, rearrangement and cyclization of allyl and pentadienyl peroxyl radicals, and homolytic substitution of carbon radicals on the peroxide bond. A physical organic approach to the problem of free radicals in biology and medicine is highlighted in this Perspective with stereochemical, kinetic, and extrathermodynamic probes applied to the study of mechanism. A radical clock permits the determination of free radical propagation rate constants, and 7-dehydrocholesterol, the immediate biosynthetic precursor of cholesterol, is found by this clock to be one of the most oxidizable lipids known. The consequences of the extreme reactivity of 7-dehydrocholesterol on human health is the focus of a current research theme in the author's laboratory. PMID:23445181

  7. Effects of a motilin receptor agonist (ABT-229) on upper gastrointestinal symptoms in type 1 diabetes mellitus: a randomised, double blind, placebo controlled trial

    OpenAIRE

    TALLEY, N; Verlinden, M; Geenen, D. van; Hogan, R; Riff, D.; Mccallum, R.; Mack, R

    2001-01-01

    INTRODUCTION—Erythromycin, a motilin agonist, is a potent prokinetic. ABT-229 is a specific motilin agonist that dose dependently accelerates gastric emptying. Dyspepsia and gastroparesis are common problems in type 1 diabetes mellitus. We aimed to evaluate the efficacy of ABT-229 in symptomatic diabetic patients with and without delayed gastric emptying.?METHODS—Patients with type 1 diabetes and postprandial symptoms were randomised (n=270). Based on a validated C13 octanoic acid breath test...

  8. [Fundamental model assays on chemical damages to ribonucleic acids caused by oxygen radicals in aqueous solution].

    Science.gov (United States)

    Lickl, E; Alth, G; Ebermann, R; Tuma, K

    1986-12-01

    A partial decomposition of RNA molecules in Saccharomyces cerevisiae is caused by photochemically produced superoxide anion radical (O2-.). Hydroxyl radicals (OH.) lead to complete destruction of RNA. Such radicals as originating from peroxidase-hydrogen peroxide reaction cause a partial decomposition of RNA molecules. All RNA species are damaged to the same extent by radicals. Damages due to oxygen radicals can be prevented or reduced by strong radical captors (dimethyl sulfoxide, 1,4-diazabicyclo-(2,2,2)-octane or superoxide dismutase). All these reactions proceed in aqueous solution. Correlations with the use of radicals in radiotherapy are discussed. PMID:3027909

  9. Fundamental model assays on chemical damages to ribonucleic acids in aqueous solution caused by oxygen radicals

    International Nuclear Information System (INIS)

    A partial decomposition of RNA molecules in Saccharomyces cerevisiae is caused by photochemically produced superoxide anion radical (O2.-). Hydroxyl radicals (OH.) lead to complete destruction of RNA. Such radicals as originating from peroxidase-hydrogen peroxide reaction cause a partial decomposition of RNA molecules. All RNA species are damaged to the same extent by radicals. Damages due to oxygen radicals can be prevented or reduced by strong radical captors (dimethyl sulfoxide, 1,4-diazabicyclo-(2,2,2)-octane or superoxide dismutase). All these reactions proceed in aqueous solution. Correlations with the use of radicals in radiotherapy are discussed. (orig.)

  10. Atmospheric chemistry of perfluorinated carboxylic acids: Reaction with OH radicals and atmospheric lifetimes

    DEFF Research Database (Denmark)

    Hurley, MD; Andersen, Mads Peter Sulbæk

    2004-01-01

    Relative rate techniques were used to study the kinetics of the reactions of OH radicals with a homologous series of perfluorinated acids, F(CF2)(n)COOH (n = 1, 2, 3, 4), in 700 Torr of air at 296 +/- 2 K. For n > 1, the length of the F(CF2)(n) group had no discernible impact on the reactivity of the molecule. For n = 1, k(OH + F(CF2)(n)COOH) = (9.35 +/- 2.08) x 10(-14) cm(3) molecule(-1) s(-1). For n = 2-4, k(OH + F(CF2)(n)COOH) = (1.69 +/- 0.22) x 10(-13) cm(3) molecule(-1) s(-1). Dimerization constants for 2F(CF2)(n)COOH = (F(CF2)(n)COOH)(2) were determined to be 0.32 +/- 0.03 Torr(-1), 0.30 +/- 0.03 Torr(-1), 0.41 +/- 0.04 Torr(-1), and 0.46 +/- 0.05 Torr(-1) for n = 1, 2, 3. 4, respectively. Atmospheric lifetimes of F(CF2)(n)COOH with respect to reaction with OH radicals are estimated to be approximately 230 days for n = 1 and 130 days for n > 1. Reaction with OH radicals is a minor atmospheric fate of F(CF2)(n)COOH. The major atmospheric removal mechanism for F(CF2)(n)COOH is believed to be wet and dry deposition which probably occurs on a time scale of the order of 10 days.

  11. Hydrogen peroxide and hydroxyl radical formation by methylene blue in the presence of ascorbic acid

    International Nuclear Information System (INIS)

    Using ESR we have demonstrated the formation of the ascorbate free radical from sodium ascorbate, methylene blue and light. In oxygen uptake experiments we have observed the production of hydrogen peroxide while spin trapping experiments have revealed the iron catalyzed production of the hydroxyl free radical in this system. The presence of this highly reactive radical suggests that it could be the radical that initiates free radical damage in this photodynamic system. (orig.)

  12. Free radical reaction pathway, thermohemistry of peracetic acid homolysis and its application for phenol degradation: spectroscopic sti=udy and quantum chemistry calculations

    OpenAIRE

    Rokhina, E.V.; Makarova, K.; Golovina, E.A.; As, H (Henk) van; Virkutyte, J.

    2010-01-01

    The homolysis of peracetic acid (PAA) as a relevant source of free radicals (e.g., •OH) was studied in detail. Radicals formed as a result of chain radical reactions were detected with electron spin resonance and nuclear magnetic resonance spin trapping techniques and subsequently identified by means of the simulation-based fitting approach. The reaction mechanism, where a hydroxyl radical was a primary product of O?O bond rupture of PAA, was established with a complete assessment of rele...

  13. The atmospheric degradation reaction of dehydroabietic acid (DHAA) initiated by OH radicals and O3.

    Science.gov (United States)

    Bai, Jing; Sun, Xiaomin; Zhang, Chenxi; Zhao, Yuyang; Gong, Chen

    2013-08-01

    Dehydroabietic acid (DHAA) is the major marker compound emitted from the burning of conifer. In this paper, the atmospheric mechanism of DHAA initiated by OH radicals and O3 was studied at the MPWB1K/6-31+G(d,p)//MPWB1K/6-311+G(3df,2p) level. For OH radicals, two types of reactions including OH addition and hydrogen abstraction were investigated. The cycloaddition reactions of O3 were considered. The rate constants over the temperature range of 200-400 K were calculated with the Rice-Ramsperger-Kassel-Marcus (RRKM) theory. At 298 K and under the pressure of 760 Torr, the whole rate constants are 0.89×10(-11) cm(3) molecule(-1) s(-1) and 2.29×10(-20) cm(3) molecule(-1) s(-1) for DHAA+OH and DHAA+O3, respectively. This study can be regarded as an attempt to investigate the OH-initiated and O3-initiated photochemical reaction mechanisms of DHAA in the atmosphere. PMID:23561857

  14. The BH3 Mimetic ABT-737 Induces Cancer Cell Senescence

    OpenAIRE

    Song, Jin H.; Kandasamy, Karthikeyan; Zemskova, Marina; Lin, Ying-Wei; Kraft, Andrew S.

    2010-01-01

    ABT-737, a small molecule cell-permeable Bcl-2 antagonist that acts by mimicking BH3 proteins, induces apoptotic cell death in multiple cancer types. However, when incubated with this agent many solid tumor cell lines do not undergo apoptosis. The current study reveals a novel mechanism whereby ABT-737 when added to apoptosis-resistant cancer cells has profound biologic effects. In PV-10 cells, a renal cell carcinoma that does not die after ABT-737 treatment, this agent induces a two-fold cha...

  15. Lewis acid-water/alcohol complexes as hydrogen atom donors in radical reactions.

    Science.gov (United States)

    Povie, Guillaume; Renaud, Philippe

    2013-01-01

    Water or low molecular weight alcohols are, due to their availability, low price and low toxicity ideal reagents for organic synthesis. Recently, it was reported that, despite the very strong BDE of the O-H bond, they can be used as hydrogen atom donors in place of expensive and/or toxic group 14 metal hydrides when boron and titanium(III) Lewis acids are present. This finding represents a considerable innovation and uncovers a new perspective on the paradigm of hydrogen atom transfers to radicals. We discuss here the influence of complex formation and other association processes on the efficacy of the hydrogen transfer step. A delicate balance between activation by complex formation and deactivation by further hydrogen bonding is operative. PMID:23967699

  16. Absolute rate constants of alkoxyl radical reactions in aqueous solution

    International Nuclear Information System (INIS)

    The pulse radiolysis technique was used to generate the alkoxyl radical derived from tert-butyl hydroperoxide (/sup t/BuOOH) in aqueous solution. The reactions of this radical with 2,2'-azinobis(3-ethyl-6-benzothiazolinesulfonate) (ABTS) and promethazine were monitored by kinetic spectroscopy. The unimolecular decay rate constant of the tert-butoxyl radical (/sup t/BuO) was determined to be 1.4 x 106 s-1. On the basis of this value, the rate constants for /sup t/BuO attack on quercetin, crocin, crocetin, ascorbate, isoascorbate, trolox c, glutathione, thymidine, adenosine, guanosine, and unsaturated fatty acids were determined. In addition, the reaction of /sup t/BuO with the polyunsaturated fatty acids (PUFA) was observed by directly monitoring the formation of the fatty acid pentadienyl radicals. Interestingly, the attack of /sup t/BuO on PUFA was found to be faster by about one order of magnitude as compared to the same reaction in a nonpolar solvent

  17. On the ESR detection of the ?-radical RNHC-dot O in irradiated crystals of 5,5-dihydroxybarbituric acid (alloxan) trihydrate

    Science.gov (United States)

    Sagstuen, Einar; Skjærvø, Halvard

    1981-12-01

    In single crystals of 5,5-dihydroxybarbituric acid (alloxan) trihydrate, an ESR absorption was observed after irradiation at 77 K which is ascribed to a ?-radical RNH? = O. Its spectral parameters are described and compared to those from the structurally similar ?-acyl radical in malonic and succinic acid. It is suggested that the radical is formed from the primary oxidation product RC?(OH) through electronic rearrangements leading to an opening of the pyrimidine ring.

  18. Polyphenolic Contents and Free Radical Scavenging Potential of Extracts from Leaves of Ocimum americanum L.

    Directory of Open Access Journals (Sweden)

    A.J. Afolayan

    2013-01-01

    Full Text Available This study assessed the polyphenolic contents and antioxidant activity of ethanol, butanol and ethyl acetate extracts of Ocimum americanum leaves using in vitro models. The ability of the extracts to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH?, 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid (ABTS?+, hydrogen peroxide (H2O2, Nitric Oxide (NO and hydroxyl radical (OH? was investigated. The inhibition of lipid oxidation, reducing power, total flavonoids, phenols and flavonols contents of the extracts were also determined using spectrophotometric methods. The result revealed highest concentration of polyphenolic compounds in the ethanol extract followed by n-butanol while ethyl acetate extract contained the least concentration. Free radical scavenging potentials of the extracts were found to be proportional to their respective polyphenolic contents. This study provides evidence that O. americanum leaves contain biologically active components with effective antioxidant activity and thus could be used for the management of radical related diseases.

  19. Continuous measurement of oxygen consumption by linoleic acid membranes exposed to free radicals generated by ?-radiation

    International Nuclear Information System (INIS)

    Vesicles enclosed by membranes prepared from linoleic acid were exposed in the chamber of an oxygen electrode to free radicals generated by 60Co ?-rays. Oxidation was observed by oxygen consumption, conjugated diene formation, and tri-iodide assay for hydroperoxides. There was a dose-dependent lag period before onset of rapid peroxidation. Radiation chemical yields (G-values) ranged from 4.45 to 19.37 ?-mol J-1 for maximum rates of oxygen consumption and from 2.18 to 16.37 ?mol J-1 for maximum rates of hydroperoxide production when the radiation dose-rate was varied between 5.39 and 0.14 Gy min-1. The magnitude of these G-values and the linear relationship between yield of hydroperoxide and (dose-rate)1/2 were indicative of a chain mechanism for peroxidation operating in membranes. Lack of congruence between the amount of oxygen consumed and hydroperoxide formed suggested that the oxygen consumed in membrane oxidation led to the formation of oxidized derivatives of linoleic acid additional to the hydroperoxides. (author)

  20. Bioactive compounds from several tropical fruits and correlation by multivariate analysis to free radical scavenger activity

    Scientific Electronic Library Online (English)

    Gisela P.M., Barreto; Marta T., Benassi; Adriana Z., Mercadante.

    1856-18-01

    Full Text Available O alto consumo de frutas tem sido associado à baixa incidência de doenças crônico-degenerativas, provavelmente devido à presença de compostos bioativos, como os antioxidantes, nestes alimentos. Os teores de compostos bioativos -ácido ascórbico, fenólicos totais, flavonóides e carotenóides totais - f [...] oram determinados em polpas obtidas a partir de 18 frutas tropicais adquiridas no Brasil. A atividade anti-radical livre foi avaliada pelo método ABTS. As frutas que apresentaram maior teor de compostos bioativos foram buriti, cajá-manga, canistel, murici, physalis, piquia e tucumã. Considerando a composição dos compostos bioativos analisados e as atividades anti-radical livre, as frutas foram divididas em 5 grupos, segundo Análise Hierárquica de Agrupamentos. Aplicando a Análise de Componentes Principais, a atividade anti-radical livre mostrou alta correlação com compostos fenólicos totais (r = 0,99) e flavonóides (r = 0,86); porém, a correlação encontrada foi muito pequena para ácido ascórbico (r = 0,02) e carotenóides totais (r = 0,08). Abstract in english High ingestion of fruits has been associated with low incidence of chronic-degenerative diseases, probably due to the presence of bioactive compounds in these foods, such as antioxidants. The levels of bioactive compounds - ascorbic acid, total phenolics, flavonoids and carotenoids - were determined [...] in 18 pulps obtained from tropical fruits acquired in Brazil. The free radical scavenger activity was evaluated by the ABTS assay. The fruits that showed higher levels of bioactive compounds were buriti, otaheite apple, egg-fruit, golden spoon, physalis, piquia and star nut palm. Considering the composition of bioactive compounds and free radical scavenger capacities the fruits were divided into five groups, according to Hierarchical Cluster Analysis. Applying Principal Component Analysis, free radical scavenger showed high correlation with total phenolic compounds (r = 0.99) and flavonoids (r = 0.86); however, the correlation was found to be very poor with ascorbic acid (r = 0.02) and with total carotenoids levels (r = 0.08).

  1. Manganese(II)-bicarbonate-mediated catalytic activity for hydrogen peroxide dismutation and amino acid oxidation: detection of free radical intermediates.

    OpenAIRE

    Yim, M B; Berlett, B S; Chock, P.B; Stadtman, E R

    1990-01-01

    To examine the structural identities of reactive free radicals and the mechanism of the oxidative modification of proteins, we used EPR and spin-trapping methods to investigate the oxidation of amino acids by H2O2 as well as the decomposition of H2O2 itself catalyzed by Mn(II) ions. Superoxide and hydroxyl radicals (O2-. and OH.) were trapped by a spin trap, 5,5-dimethyl-1-pyrroline-1-oxide (DMPO), in a reaction mixture containing Mn(II) and H2O2 in bicarbonate/CO2 buffer. When Hepes was used...

  2. Bond Dissociation Free Energies (BDFEs) of the Acidic H-A Bonds in HA(*)(-) Radical Anions by Three Different Pathways.

    Science.gov (United States)

    Zhao, Yongyu; Bordwell, Frederick G.

    1996-09-20

    Cleavage of radical anions, HA(*)(-), have been considered to give either H(*) + A(-) (path a) or H(-) + A(*) (path b), and factors determining the preferred mode of cleavage have been discussed. It is conceivable that cleavage to give a proton and a radical dianion, HA(*)(-) right harpoon over left harpoon H(+) + A(*)(2)(-) (path c), might also be feasible. A method, based on a thermodynamic cycle, to estimate the bond dissociation free energy (BDFE) by path c has been devised. Comparison of the BDFEs for cleavage of the radical anions derived from 24 nitroaromatic OH, SH, NH, and CH acids by paths a, b, c has shown that path c is favored thermodynamically. PMID:11667531

  3. Caffeic acid inhibits the formation of 1-hydroxyethyl radical in the reaction mixture of rat liver microsomes with ethanol partly through its metal chelating activity.

    Science.gov (United States)

    Ikeda, Hideyuki; Kimura, Yuka; Masaki, Miho; Iwahashi, Hideo

    2011-05-01

    Effect of caffeic acid on the formation of 1-hydroxyethyl radicals via the microsomal ethanol-oxidizing system pathway was examined. The electron spin resonance spin trapping showed that 1-hydroxyethyl radicals form in the control reaction mixture which contained 0.17 M ethanol, 1 mg protein/ml rat river microsomes, 0.1 M ?-(4-pyridyl-1-oxide)-N-tert-butylnitrone, 5 mM nicotinamide adenine dinucleotide phosphate and 30 mM phosphate buffer (pH 7.4). When the electron spin resonance spectra of the control reaction mixtures with caffeic acid were measured, caffeic acid inhibited the formation of 1-hydroxyethyl radicals in a concentration dependent manner. Gallic acid, dopamine, l-dopa, chlorogenic acid and catechin also inhibited the formation of 1-hydroxyethyl radicals. Above results indicated that the catechol moiety is essential to the inhibitory effect. Caffeic acid seems to chelate of iron ion at the catechol moiety. Indeed, the inhibitory effect by caffeic acid was greatly diminished in the presence of desferrioxamine, a potent iron chelator which removes iron ion in the Fe (III)-caffeic acid complex. Since Fe (III)-desferrioxamine complex is active for the 1-hydroxyethyl radicals formation, caffeic acid inhibits the formation of 1-hydroxyethyl radicals in the reaction mixture partly through its metal chelating activity. PMID:21562637

  4. Dimers in ?-pinene secondary organic aerosol: effect of hydroxyl radical, ozone, relative humidity and aerosol acidity

    Science.gov (United States)

    Kristensen, K.; Cui, T.; Zhang, H.; Gold, A.; Glasius, M.; Surratt, J. D.

    2014-04-01

    The formation of secondary organic aerosol (SOA) from both ozonolysis and hydroxyl radical (OH)-initiated oxidation of ?-pinene under conditions of high nitric oxide (NO) concentrations with varying relative humidity (RH) and aerosol acidity was investigated in the University of North Carolina dual outdoor smog chamber facility. SOA formation from ozonolysis of ?-pinene was enhanced relative to that from OH-initiated oxidation in the presence of initially high-NO conditions. However, no effect of RH on SOA mass was evident. Ozone (O3)-initiated oxidation of ?-pinene in the presence of ammonium sulfate (AS) seed coated with organic aerosol from OH-initiated oxidation of ?-pinene showed reduced nucleation compared to ozonolysis in the presence of pure AS seed aerosol. The chemical composition of ?-pinene SOA was investigated by ultra-performance liquid chromatography/electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-Q-TOFMS), with a focus on the formation of carboxylic acids and high-molecular weight dimers. A total of eight carboxylic acids and four dimers were identified, constituting between 8 and 12% of the total ?-pinene SOA mass. OH-initiated oxidation of ?-pinene in the presence of nitrogen oxides (NOx) resulted in the formation of highly oxidized carboxylic acids, such as 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA) and diaterpenylic acid acetate (DTAA). The formation of dimers was observed only in SOA produced from the ozonolysis of ?-pinene in the absence of NOx, with increased concentrations by a factor of two at higher RH (50-90%) relative to lower RH (30-50%). The increased formation of dimers correlates with an observed increase in new particle formation at higher RH due to nucleation. Increased aerosol acidity was found to have a negligible effect on the formation of the dimers. SOA mass yield did not influence the chemical composition of SOA formed from ?-pinene ozonolysis with respect to carboxylic acids and dimers. The results support the formation of the high-molecular weight dimers through gas-phase reactions of the stabilized Criegee Intermediate (sCI) formed from the ozonolysis of ?-pinene. The high molecular weight and polar nature of dimers formed in the gas phase may explain increased particle number concentration as a result of homogenous nucleation. Since three of these dimers (i.e. pinyl-diaterpenyl dimer (MW 358), pinyl-diaterebyl dimer (MW 344) and pinonyl-pinyl dimer (MW 368)) have been observed in both laboratory-generated and ambient fine organic aerosol samples, we conclude that the dimers observed in this study can be used as tracers for the O3-initiated oxidation of ?-pinene, and are therefore indicative of enhanced anthropogenic activities, and that the high molecular weight and low volatility dimers result in homogenous nucleation under laboratory conditions, increasing the particle number concentration.

  5. Addition and elimination kinetics in OH radical induced oxidation of phenol and cresols in acidic and alkaline solutions

    International Nuclear Information System (INIS)

    The rates of the two consecutive reactions, OH radical addition and H2O/OH- elimination, were studied by pulse radiolysis in highly acidic (pH=1.3-1.9) and alkaline (pH?11) solutions, respectively, for phenol and for the three cresol isomers. The rate coefficient of the addition as measured by the build-up of phenoxyl radical absorbance and by a competitive method is the same (1.4±0.1)x1010 mol-1 dm3 s-1 both in acidic and alkaline solution. The rate coefficient of the H2O elimination in acidic solution is (1.6±0.2)x106 s-1, whereas the coefficient of the OH- elimination in alkaline solutions is 6-8 times higher. The kinetics of the phenoxyl radical formation was described by the two-exponential equation of the consecutive reactions: the first exponential is related to the pseudo-first-order addition, while the second to the elimination reaction. No considerable structure dependence was found in the rate coefficients, indicating that the methyl substitutent in these highly acidic or alkaline solutions influences neither the addition nor the elimination rate

  6. Gallic acid induces vascular smooth muscle cell death via hydroxyl radical production.

    Science.gov (United States)

    Qiu, X; Takemura, G; Koshiji, M; Hayakawa, Y; Kanoh, M; Maruyama, R; Ohno, Y; Minatoguchi, S; Akao, S; Fukuda, K; Fujiwara, T; Fujiwara, H

    2000-01-01

    In the present study, we investigated whether gallic acid (GA) can induce death in cultured vascular smooth muscle cells (VSMCs), and whether production of the hydroxyl radical (.OH) is involved in the process of GA action. GA killed cultured VSMCs from rat aorta, in a dosc- and time-dependent manner. Cytoplasmic shrinkage and nuclear condensation were observed light microscopically in GA-treated VSMCs, which appeared apoptotic. However, the ultrastructure of the VSMC was not typical of apoptosis: nuclear condensation was not glossy, and the plasma membrane and subccellular organelles were disrupted. Although the VSMC were positive for in situ nick end-labeling (TUNEL). they did not show a DNA ladder pattern on gel electrophoresis and were negative for T aq polymerase-based in situ ligation, which is more specific for apoptosis than TUNEL. Moreover. GA-induced cell death was not prevented by Boc-Asp-fmk (a pan-caspase inhibitor). Production of OH was detected in GA-treated VSMCs using high-performance liquid chromatography with salicylic acid as a trapping agent. Lipid peroxidation was also observed. The production of .OH was inhibited by catalase (CAT) and deferoxamine (DFX), and these treatments completely rescued VSMCs from cell death. In a cell-free system, GA produced .OH in the presence of Fe2+-EDTA, which was quenched by CAT and DFX, suggesting involvement of the Haber-Weiss reaction. Oxidative stress by reactive oxygen species, .OH in particular, is one of the mechanisms of GA-induced death of VSMCs, the mode of which was different from typical apoptosis. PMID:11199510

  7. E.S.R. of spin-trapped radicals in aqueous solutions of 5-halo derivatives of nucleic acid constituents: reactions of hydrated electrons, hydroxyl radicals and U.V. photolysis

    International Nuclear Information System (INIS)

    In order to obtain information concerning the mechanism of radio- and photosensitization due to 5-halogen substituted nucleic acid constituents, the free radicals produced in iodo-, bromo-, chloro- and fluoro-derivatives of uracil, uridine and deoxyuridine by reaction with hydrated electrons and with hydroxyl radicals and by direct U.V. photolysis have been studied by e.s.r. and spin-trapping. t-Nitrosobutane was used as the spin-trap. From 5-halogenated bases (except 5-fluorouracil) U.V. photolysis and reactions with hydrated electrons produced the uracilyl radical which was subsequently spin-trapped. When hydroxyl radical reactions were studied, the free radical at the N(1) position of the base was identified. From 5-fluorouracil U.V. photolysis generated the ?-halo radical at the C(5) position of the base. For 5-halogenated ribonucleosides and deoxyribonucleosides, free radicals located on the sugar moiety were observed for reactions with hydrated electrons, hydroxyl radicals and for U.V. photolysis. The implications of these results for understanding the mechanism of radio- and photosensitization by 5-halogenated nucleic acids are discussed. (author)

  8. Spectroscopic studies on the antioxidant activity of p-coumaric acid

    Science.gov (United States)

    Kiliç, Ismail; Ye?ilo?lu, Ye?im

    2013-11-01

    p-coumaric acid (4-hydroxycinnamic acid), a phenolic acid, is a hydroxyl derivative of cinnamic acid. It decreases low density lipoprotein (LDL) peroxidation and reduces the risk of stomach cancer. In vitro radical scavenging and antioxidant capacity of p-coumaric acid were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2?-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. p-Coumaric acid inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 ?g/mL concentration. On the other hand, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), ?-tocopherol and ascorbic acid displayed 66.8%, 69.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, p-coumaric acid had an effective DPPHrad scavenging, ABTSrad + scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, ?-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that p-coumaric acid can be used in the pharmacological and food industry because of these properties.

  9. Effects of precursor concentration and acidic sulfate in aqueous glyoxal-OH radical oxidation and implications for secondary organic aerosol.

    Science.gov (United States)

    Tan, Yi; Perri, Mark J; Seitzinger, Sybil P; Turpin, Barbara J

    2009-11-01

    Previous experiments demonstrated that aqueous OH radical oxidation of glyoxal yields low-volatility compounds. When this chemistry takes place in clouds and fogs, followed by droplet evaporation (or if it occurs in aerosol water), the products are expected to remain partially in the particle phase, forming secondary organic aerosol (SOA). Acidic sulfate exists ubiquitously in atmospheric water and has been shown to enhance SOA formation through aerosol phase reactions. In this work, we investigate how starting concentrations of glyoxal (30-3000 microM) and the presence of acidic sulfate (0-840 microM) affect product formation in the aqueous reaction between glyoxal and OH radical. The oxalic acid yield decreased with increasing precursor concentrations, and the presence of sulfuric acid did not alter oxalic acid concentrations significantly. A dilute aqueous chemistry model successfully reproduced oxalic acid concentrations, when the experiment was performed at cloud-relevant concentrations (glyoxal clouds and in wet aerosols. They validate for the first time the accuracy of model predictions at cloud-relevant concentrations. These results suggest that cloud processing of glyoxal could be an important source of SOA. PMID:19924930

  10. Effects of Precursor Concentration and Acidic Sulfate in Aqueous Glyoxal?OH Radical Oxidation and Implications for Secondary Organic Aerosol

    OpenAIRE

    Tan, Yi; Perri, Mark J.; Seitzinger, Sybil P.; Turpin, Barbara J.

    2009-01-01

    Previous experiments demonstrated that aqueous OH radical oxidation of glyoxal yields low-volatility compounds. When this chemistry takes place in clouds and fogs, followed by droplet evaporation (or if it occurs in aerosol water), the products are expected to remain partially in the particle phase, forming secondary organic aerosol (SOA). Acidic sulfate exists ubiquitously in atmospheric water and has been shown to enhance SOA formation through aerosol phase reactions. In this work, we inves...

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

    OpenAIRE

    Tan, Y.; Lim, Y. B.; Altieri, K. E.; Seitzinger, S. P.; Turpin, B. J.

    2011-01-01

    Previous experiments have demonstrated that the aqueous OH radical oxidation of methylglyoxal produces low volatility products including 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 is an important intermediate in aqueous methylglyoxal oxidation and a ubiquitous product of gas phase photochemistry, making it a potential "aqueous" SOA precursor ...

  12. Thiyl radical-induced cis-trans-isomerization of arachidonic acid inhibits prostaglandin metabolism

    International Nuclear Information System (INIS)

    Complete text of publication follows. Thiyl radicals radiolytically generated from thiophenol in methanolic solution are known to isomerise double bonds of poly-unsaturated fatty acids (PUFA). ?-irradiating of such a system containing all-cis 5,8,11,14 eicosatetraenoic acid (arachidonic acid, AA) with low doses (0.1-0.8 kGy) results in a mixture of 8 to 32% mono-trans-isomers. Here we report about the influence of mono-trans-AA on the primary steps of AA-metabolism and prostaglandin synthesis, catalysed by cyclooxygenase (COX). In the cell-free model system the reaction of COX-1 with AA was analysed by controlling the oxygen level during the enzymatic reaction. As an example, a mixture of a low quantity of mono-trans-isomerized AA (10%) and 90% all-cis-isomer exhibits a marked reduced oxygen consumption by 45%. As further proofs - the yield of reactive oxygen species (ROS) generated by the COX-coupled peroxidase reaction was detected, - and the COX-1 activity in presence of different amounts of trans-AA was characterized using a photometric assay based on the oxidation of TMPD. All these methods indicated semiquantitatively a reduced activity of COX-1, depending on the trans-isomer yield. Therefore, an inhibition of COX-1 activity by only one trans-double-bond in AA could be concluded. Furthermore, in vitro cell-line experiments were performed analysing the influence of mono-trans-isomerized AA on the activity of the cell-own COX-2. Hence, VD3-differentiated and LPS-stimulated monocyte-like cells were incubated with mono-trans-AA and ROS-production was detected by the chemiluminescence measurements mentioned above. Compared to the reaction with all-cis-AA we found a considerable lowered formation of ROS. Likewise, we obtained a reduced PGE2-expression between 15 and 40% for cells treated with 8 to 29% trans-AA. The model as well as in vivo experiments demonstrate an inhibition effect of mono-trans-AA and give rise for postulating an enzyme blocking mechanism for COX-1 and COX-2 by trans-isomers

  13. In vitro effects of arylhydrocoumarin on free radicals and oxidative stress in erythrocytes and Saccharomyces cerevisiae.

    Science.gov (United States)

    de Freitas, Rizângela L M; Oliveira, George L da Silva; de Freitas, Rivelilson M; Barreiros, André L B S; David, Juceni P; Alves, Clayton Q; Pinto, Charleston R; David, Jorge M

    2014-01-01

    Neoflavonoids comprise a group of natural compounds with varied chemical structures and promising pharmacological properties, including antioxidant capacity. This work describes an evaluation of the in vitro antioxidant capacity of a new coumarin derivative, i.e., 7-acetoxy-4-aryl-3,4-dihydrocoumarin, in terms of its ability to quench the 2,2- diphenyl-1-picrylhydrazyl (DPPH•), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+), hydroxyl (OH•) and superoxide anion (O2(•-)) radicals, as well as its capacity to initiate electron transfer by reducing potential and inhibit lipid peroxidation by TBARS (thiobarbituric acid reactive substances) method. In addition, the antioxidant capacity of 7-acetoxy-4-aryl-3,4-dihydrocoumarin was evaluated against oxidative damage induced by hydrogen peroxide in erythrocyte suspensions and S. cerevisiae strains. In all methodologies investigated, high antioxidant capacities above 65% were demonstrated by 7-acetoxy-4-aryl-3,4-dihydrocoumarin against the DPPH(•), ABTS(•+), OH(•) and O2(•-) radicals. The ability of 7-acetoxy-4-aryl-3,4-dihydrocoumarin to inhibit oxidative damage induced by hydrogen peroxide in erythrocytes and S. cerevisiae strains demonstrates the importance of this compound in the protection against oxidative stress at the cellular level. Thus, the results obtained in this study suggest that 7-acetoxy-4-aryl-3,4-dihydrocoumarin can assist the development of new antioxidant products for possible use in the prevention or reduction of diseases related to oxidative stress. PMID:25382304

  14. Influence of fatty acid on lipase-catalyzed synthesis of ascorbyl esters and their free radical scavenging capacity.

    Science.gov (United States)

    Stojanovi?, Marija; Carevi?, Milica; Mihailovi?, Mladen; Veli?kovi?, Dušan; Dimitrijevi?, Aleksandra; Milosavi?, Nenad; Bezbradica, Dejan

    2014-09-15

    Fatty acid ascorbyl esters are recently emerging food, cosmetic, and pharmaceutical additives, which can be prepared in eco-friendly way by using lipases as catalysts. Since they are amphiphilic molecules which possess high free radical scavenging capacity, they can be applied as liposoluble antioxidants, as well as emulsifiers and biosurfactants. In this study, the influence of a wide range of acyl donors on ester yield in lipase-catalyzed synthesis and ester antioxidant activity was examined. Among saturated acyl donors, higher yields and antioxidant activities of esters were achieved when short chain fatty acids were used. Oleic acid gave the highest yield overall and its ester exhibited high antioxidant activity. Optimization of experimental factors showed that the highest conversion (60.5%) in acetone was achieved with 5 g L(-1) of lipase, 50 mM of vitamin C, ten-fold molar excess of oleic acid, and 0.7 mL L(-1) of initial water. Obtained results showed that even short and medium chain ascorbyl esters could be synthesized with high yields and retained (or even exceeded) free radical scavenging capacity of L-ascorbic acid, indicating prospects of broadening their application in emulsions and liposomes. This article is protected by copyright. All rights reserved. PMID:25224149

  15. Kinetics of radical decay in crystalline amino acids. II. High-temperature study

    International Nuclear Information System (INIS)

    Radical decay in x-irradiated L-leucine, and DL-valine, L- and DL-alanine, and L-arginine hydrochloride was studied between 300 and 4300K. Free radical decay was observed to take place with two distinct rates: an initial short duration process having an activation energy of 18 kcal/mole and a second, slower process. In most cases, the fraction of radicals decaying by the faster process is the same as the very slow room-temperature decay previously observed. The major process has a 3--6-kcal/mole higher activation energy. There is no evidence of radical conversion in either the initial or the slower process. However, in at least two cases residual peroxy radicals were observed at the termination of the slower process. Both decays obey second-order rate laws. The peroxy radical in at least one case decayed by a second-order law also. Vacancy controlled bulk diffusion is proposed for the major process, and the initial process is thought to be a conformationally aided bulk diffusion. It was observed that at any given temperature the spin concentration reaches a constant value. Increasing the temperature results in a second decay to a new constant value in a stepwise fashion. In the case of hydrated L-arginine hydrochloride and its partially deuterated derivative, the decay was found to be related to the dehydration process. A rapidly propagating radical transfer mechanism involving hydrogen abstraction is postulated for this decay process this decay process

  16. AVALIAÇÃO DA ATIVIDADE ANTIOXIDANTE DE DIFERENTES CERVEJAS APLICANDO OS MÉTODOS ABTS E DPPH

    Directory of Open Access Journals (Sweden)

    G. L. FREITAS

    2009-01-01

    Full Text Available

    Os compostos fenólicos são substâncias presentes naturalmente nos vegetais que podem atuar como antioxidantes. Na cerveja desempenham um papel importante nas características sensoriais (cor, aroma e sabor e nutricionais da cerveja. O objetivo deste trabalho foi determinar o conteúdo de compostos fenólicos totais e flavonóis em diversos tipos de cervejas comercializada no Brasil, assim como determinar a capacidade antioxidante in vitro realizada por dois métodos, o radical ABTS•+ (ácido 2,2'-azino-bis (3-etilbenzotiazolin 6-sulfônico e o radical DPPH• (2,2-Difenil-1-picrilhidrazilo. Para determinar os polifenóis totais foi utilizado o método de Folin-Ciocalteau e o método DMACA para os flavanóis. Os resultados mostraram que o conteúdo de compostos fenólicos nas cervejas analisadas variou de 249,73 ± 8,44 a 808,58 ± 7,42 mg/L. A cerveja escura de trigo, apresentou os maiores valores de polifenóis totais, seguida das cervejas escura de cevada, da clara de trigo e das cervejas clara de cevada. Foram encontrados resultados significativos para atividade antioxidante aplicando o método ABTS, valores de 911,79 ± 2,21 a 3857,66 ± 6,07 Mol TEAC/L dependendo do tipo de cerveja e pelo método DPPH, de 2840,12 ± 1,09 a 4290,77± 6,19 Mol TEAC/L. O conteúdo de flavanóis (equivalente a mg catequina/L de amostra., variaram em média de 1,93 ± 0,07 mg/L a 2,79 ± 0,08 mg/L para as cervejas claras e de 2,14 ± 0,04 mg/L a 5,09 ± 0,08 mg/L para as cervejas escuras.

  17. Caracterização físico-química de polpas de frutos da Amazônia e sua correlação com a atividade anti-radical livre / Physical and chemical characterization of fruit pulps from Amazonia and their correlation to free radical scavenger activity

    Scientific Electronic Library Online (English)

    Gisele André Baptista, Canuto; Ana Augusta Odorissi, Xavier; Leandro Camargo, Neves; Marta de Toledo, Benassi.

    1196-12-01

    Full Text Available Características físico-químicas (cor, pH, acidez total titulável, sólidos solúveis totais, conteúdo de lipídios e umidade) e níveis de compostos bioativos (ácido ascórbico, fenólicos totais) foram determinados em quinze amostras de polpas de frutos procedentes da região Amazônica (abiu, acerola, aça [...] í, araçá-boi, bacaba, bacuri, buriti, cajá, cajarana, caju, cupuaçu, graviola, murici, noni e tamarindo). A atividade de radicais livres foi avaliada pelo método de ABTS. Algumas polpas apresentaram alta potencialidade antioxidante, associada com a atividade antirradicais livres obtida e os conteúdos dos componentes bioativos como compostos fenólicos e ácido ascórbico, destacando-se acerola e acaí. O conteúdo total de compostos fenólicos foi correlacionado à capacidade antioxidante das polpas. Abstract in english Physical and chemical characteristics (color, pH, titratable acidity, total soluble solids, lipid content, moisture) and levels of bioactive compounds (ascorbic acid, total phenolics) were determined in fifteen samples of fruit pulps from Amazonia (abiu, acerola, açaí, araça-boi, bacaba, bacuri, bur [...] iti, cajá, cajarana, caju, cupuaçu, graviola, murici, noni e tamarindo). The free radical scavenger activity was evaluated by the ABTS assay. Some pulps presented high antioxidant potential, associated with the free radical scavenger activity measured and the content of bioactive components, such as phenolic compounds and ascorbic acid, especialy in acerola and açaí. The total phenolic content was correlated to antioxidant capacity of pulps.

  18. Caracterização físico-química de polpas de frutos da Amazônia e sua correlação com a atividade anti-radical livre Physical and chemical characterization of fruit pulps from Amazonia and their correlation to free radical scavenger activity

    Directory of Open Access Journals (Sweden)

    Gisele André Baptista Canuto

    2010-12-01

    Full Text Available Características físico-químicas (cor, pH, acidez total titulável, sólidos solúveis totais, conteúdo de lipídios e umidade e níveis de compostos bioativos (ácido ascórbico, fenólicos totais foram determinados em quinze amostras de polpas de frutos procedentes da região Amazônica (abiu, acerola, açaí, araçá-boi, bacaba, bacuri, buriti, cajá, cajarana, caju, cupuaçu, graviola, murici, noni e tamarindo. A atividade de radicais livres foi avaliada pelo método de ABTS. Algumas polpas apresentaram alta potencialidade antioxidante, associada com a atividade antirradicais livres obtida e os conteúdos dos componentes bioativos como compostos fenólicos e ácido ascórbico, destacando-se acerola e acaí. O conteúdo total de compostos fenólicos foi correlacionado à capacidade antioxidante das polpas.Physical and chemical characteristics (color, pH, titratable acidity, total soluble solids, lipid content, moisture and levels of bioactive compounds (ascorbic acid, total phenolics were determined in fifteen samples of fruit pulps from Amazonia (abiu, acerola, açaí, araça-boi, bacaba, bacuri, buriti, cajá, cajarana, caju, cupuaçu, graviola, murici, noni e tamarindo. The free radical scavenger activity was evaluated by the ABTS assay. Some pulps presented high antioxidant potential, associated with the free radical scavenger activity measured and the content of bioactive components, such as phenolic compounds and ascorbic acid, especialy in acerola and açaí. The total phenolic content was correlated to antioxidant capacity of pulps.

  19. Free Radical Scavenging Activity of Kielmeyera variabilis (Clusiaceae

    Directory of Open Access Journals (Sweden)

    Dulce Helena Siqueira Silva

    2013-02-01

    Full Text Available As part of our ongoing research on antioxidant agents from Brazilian flora, we screened the free radical scavenging activity of two extracts and eight fractions of Kielmeyera variabilis (Clusiaceae using DPPH· (2,2-diphenyl-1-picrylhydrazyl-hydrate and ABTS·+ [2,2'-azinobis(3-ethylenebenzothiazoline-6-sulfonic acid] colorimetric assays. The ethyl acetate and n-butanol fractions of the leaves of K. variabilis displayed the strongest activity (IC50 of 3.5 ± 0.3 and 4.4 ± 0.2 ?g mL?1 for DPPH· and 6.6 ± 0.4 and 3.1 ± 0.1 ?g mL?1 for ABTS·+, respectively. Chromatographic fractionation of the most potent fractions led to identification of three flavonols with previously described antioxidant activity, quercitrin (1, quercetin-3-O-b-glucoside (3, and quercetin-3-O-b-galactoside (4, and of one biflavone, podocarpusflavone A (2. This is the first time that the presence of these flavonoids in Kielmeyera variabilis has been reported.

  20. In vitro and in vivo antiviral activity and resistance profile of the hepatitis C virus NS3/4A protease inhibitor ABT-450.

    Science.gov (United States)

    Pilot-Matias, Tami; Tripathi, Rakesh; Cohen, Daniel; Gaultier, Isabelle; Dekhtyar, Tatyana; Lu, Liangjun; Reisch, Thomas; Irvin, Michelle; Hopkins, Todd; Pithawalla, Ron; Middleton, Timothy; Ng, Teresa; McDaniel, Keith; Or, Yat Sun; Menon, Rajeev; Kempf, Dale; Molla, Akhteruzzaman; Collins, Christine

    2015-02-01

    The development of direct-acting antiviral agents is a promising therapeutic advance in the treatment of hepatitis C virus (HCV) infection. However, rapid emergence of drug resistance can limit efficacy and lead to cross-resistance among members of the same drug class. ABT-450 is an efficacious inhibitor of HCV NS3/4A protease, with 50% effective concentration values of 1.0, 0.21, 5.3, 19, 0.09, and 0.69 nM against stable HCV replicons with NS3 protease from genotypes 1a, 1b, 2a, 3a, 4a, and 6a, respectively. In vitro, the most common amino acid variants selected by ABT-450 in genotype 1 were located in NS3 at positions 155, 156, and 168, with the D168Y variant conferring the highest level of resistance to ABT-450 in both genotype 1a and 1b replicons (219- and 337-fold, respectively). In a 3-day monotherapy study with HCV genotype 1-infected patients, ABT-450 was coadministered with ritonavir, a cytochrome P450 3A4 inhibitor shown previously to markedly increase peak, trough, and overall drug exposures of ABT-450. A mean maximum HCV RNA decline of 4.02 log10 was observed at the end of the 3-day dosing period across all doses. The most common variants selected in these patients were R155K and D168V in genotype 1a and D168V in genotype 1b. However, selection of resistant variants was significantly reduced at the highest ABT-450 dose compared to lower doses. These findings were informative for the subsequent evaluation of ABT-450 in combination with additional drug classes in clinical trials in HCV-infected patients. (Study M11-602 is registered at ClinicalTrials.gov under registration no. NCT01074008.). PMID:25451053

  1. Amino acid changes in disease-associated variants differ radically from variants observed in the 1000 genomes project dataset.

    Science.gov (United States)

    de Beer, Tjaart A P; Laskowski, Roman A; Parks, Sarah L; Sipos, Botond; Goldman, Nick; Thornton, Janet M

    2013-01-01

    The 1000 Genomes Project data provides a natural background dataset for amino acid germline mutations in humans. Since the direction of mutation is known, the amino acid exchange matrix generated from the observed nucleotide variants is asymmetric and the mutabilities of the different amino acids are very different. These differences predominantly reflect preferences for nucleotide mutations in the DNA (especially the high mutation rate of the CpG dinucleotide, which makes arginine mutability very much higher than other amino acids) rather than selection imposed by protein structure constraints, although there is evidence for the latter as well. The variants occur predominantly on the surface of proteins (82%), with a slight preference for sites which are more exposed and less well conserved than random. Mutations to functional residues occur about half as often as expected by chance. The disease-associated amino acid variant distributions in OMIM are radically different from those expected on the basis of the 1000 Genomes dataset. The disease-associated variants preferentially occur in more conserved sites, compared to 1000 Genomes mutations. Many of the amino acid exchange profiles appear to exhibit an anti-correlation, with common exchanges in one dataset being rare in the other. Disease-associated variants exhibit more extreme differences in amino acid size and hydrophobicity. More modelling of the mutational processes at the nucleotide level is needed, but these observations should contribute to an improved prediction of the effects of specific variants in humans. PMID:24348229

  2. Antioxidant activity and free radical-scavenging capacity of Gynura divaricata leaf extracts at different temperatures

    Directory of Open Access Journals (Sweden)

    Wan Chunpeng

    2011-01-01

    Full Text Available Background: Extraction temperature influences the total phenolic content (TPC, total flavonoid content (TFC of medicinal plant extracts to a great extend. TPC and TFC are the principle activity constituents present in the plant. The effects of extraction temperature on TPC, TFC and free radical-scavenging capacity of Gynura divaricata leaf extracts are worth to study. Materials and Methods: Folin-Ciocalteu and aluminum chloride colorimetric assay were used to determine the TPC and TFC of Gynura divaricata leaf extracts at different temperatures. The antioxidant and free radical-scavenging activity were measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH, 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid (ABTS and phosphomolybdenum methods. Results: TPC and TFC were significantly elevated with increasing extraction temperature (from 40°C to 100°C. However, TPC and TFC were not significantly different (P > 0.05 at the extraction temperatures 90°C and 100°C. Also, the extracts obtained at a higher temperature exhibited a significant free radical-scavenging activity compared with extraction at lower temperatures (P < 0.05. The TPCs (13.95-36.68 mg gallic acid equivalent/g dry material were highly correlated with DPPH (R2 = 0.9229, ABTS (R2 = 0.9951 free radical-scavenging capacity, and total antioxidant activity (R2 = 0.9872 evaluated by phosphomolybdenum method. Conclusion: The TPC and TFC of G. divaricata leaf was significantly influenced by the extraction temperatures, which were the main antioxidant constituents present in the G. divaricata plant.

  3. The Effect of Nitrate as a Radical Scavenger for the Removal of Humic Acid from Aqueous Solutions by Electron Beam Irradiation

    OpenAIRE

    Mohammad Taghi Ghaneian; Mohammad Hassan Ehrampoush; Tahereh Jasemizad; Monireh Kheirkha; Reza Amraei; Fatemeh Sahlabadi

    2013-01-01

    Introduction: Humic acids have adverse effects on the water quality, then should be removed from water resources. The aim of this study was to evaluate the effect of nitrate as a radical scavenger for removal of humic acid from aqueous solutions by electron beam irradiation. Materials and Methods: In this study, after preparation of stock humic acid solution in alkaline condition, different concentrations of humic acid (10, 25 and 50 mg/l) were prepared. Different concentrations of nitrate (2...

  4. Absolute rate constants of alkoxyl radical reactions in aqueous solution. [Tert-butyl hydroperoxide

    Energy Technology Data Exchange (ETDEWEB)

    Erben-Russ, M.; Michel, C.; Bors, W.; Saran, M.

    1987-04-23

    The pulse radiolysis technique was used to generate the alkoxyl radical derived from tert-butyl hydroperoxide (/sup t/BuOOH) in aqueous solution. The reactions of this radical with 2,2'-azinobis(3-ethyl-6-benzothiazolinesulfonate) (ABTS) and promethazine were monitored by kinetic spectroscopy. The unimolecular decay rate constant of the tert-butoxyl radical (/sup t/BuO) was determined to be 1.4 x 10/sup 6/ s/sup -1/. On the basis of this value, the rate constants for /sup t/BuO attack on quercetin, crocin, crocetin, ascorbate, isoascorbate, trolox c, glutathione, thymidine, adenosine, guanosine, and unsaturated fatty acids were determined. In addition, the reaction of /sup t/BuO with the polyunsaturated fatty acids (PUFA) was observed by directly monitoring the formation of the fatty acid pentadienyl radicals. Interestingly, the attack of /sup t/BuO on PUFA was found to be faster by about one order of magnitude as compared to the same reaction in a nonpolar solvent.

  5. Chemical constituents with free-radical-scavenging activities from the stem of Microcos paniculata.

    Science.gov (United States)

    Fan, Hua; Yang, Guang-Zhong; Zheng, Tong; Mei, Zhi-Nan; Liu, Xiang-Ming; Chen, Yu; Chen, Su

    2010-08-01

    The free-radical-scavenging activities of various solvent extracts of Microcos paniculata were evaluated through in vitro model systems, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and Co (II) EDTA-induced luminol chemiluminescence by flow injection. In all three of these systems the ethyl acetate (EtOAc) extract showed the highest free-radical-scavenging activity compared with the other three (n-BuOH, water and petroleum ether) extracts. Free-radical-scavenging assay-guided chromatographic separation of the EtOAc extract, using a normal-phase and reverse-phase silica gel column chromatography yielded five compounds: a new triterpene named methyl 3beta-O-p-hydroxy-E-cinnamoyloxy-2alpha,23-dihydroxyolean-12-en-28-oate (1), whose spectral data are presented for the first time, together with four known compounds, epicatechin (2), 3-trans-feruloyl maslinic acid (3), maslinic acid (4) and sucrose (5). All of the compounds were isolated from Microcos paniculata for the first time. The compounds were identified by spectroscopic methods. Among them, compound 2 displayed significant free-radical-scavenging activity which is similar to that of standard antioxidant ascorbic acid (V(C)) and therefore may be a promising natural antioxidant. PMID:20714312

  6. Chemical Constituents with Free-Radical-Scavenging Activities from the Stem of Microcos paniculata

    Directory of Open Access Journals (Sweden)

    Yu Chen

    2010-08-01

    Full Text Available The free-radical-scavenging activities of various solvent extracts of Microcos paniculata were evaluated through in vitro model systems, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH, 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonate (ABTS and Co (II EDTA-induced luminol chemiluminescence by flow injection. In all three of these systems the ethyl acetate (EtOAc extract showed the highest free-radical-scavenging activity compared with the other three (n-BuOH, water and petroleum ether extracts. Free-radical-scavenging assay-guided chromatographic separation of the EtOAc extract, using a normal-phase and reverse-phase silica gel column chromatography yielded five compounds: a new triterpene named methyl 3b-O-p-hydroxy-E-cinnamoyloxy-2a,23-dihydroxyolean-12-en-28-oate (1, whose spectral data are presented for the first time, together with four known compounds, epicatechin (2, 3-trans-feruloyl maslinic acid (3, maslinic acid (4 and sucrose (5. All of the compounds were isolated from Microcos paniculata for the first time. The compounds were identified by spectroscopic methods. Among them, compound 2 displayed significant free-radical-scavenging activity which is similar to that of standard antioxidant ascorbic acid (VC and therefore may be a promising natural antioxidant.

  7. Radical-scavenging compounds from olive tree (Olea europaea L.) wood.

    Science.gov (United States)

    Pérez-Bonilla, Mercedes; Salido, Sofía; van Beek, Teris A; Altarejos, Joaquín

    2014-01-01

    The purpose of this study was to complete knowledge on the chemical composition and radical-scavenging activity of olive tree wood. Two new monoterpene glycosides, (-)-oleuropeic acid 6'-O-?-D-glucopyranosyl ester (6a) and (-)-perillic acid 1'-O-?-D-primeverosyl ester (8), together with the known compounds (-)-oleuropeic acid (1), (-)-olivil (2), the aldehydic form of oleuropein aglycone (3), (+)-1-hydroxypinoresinol 1-O-?-D-glucopyranoside (4), (-)-oleuropeic acid 1'-O-?-D-glucopyranosyl ester (5), (-)-oleuropeic acid 6'-O-?-D-glucopyranosyl ester (6b), and (-)-olivil 4-O-?-D-glucopyranoside (7) were isolated from an ethyl acetate extract. The radical scavengers found (2-4 and 7) were detected and isolated with the help of the online HPLC-DAD-DPPH/ABTS technique. Compounds 2-4 and 7 displayed a higher antioxidative effect against the free radical DPPH than the reference BHT and lower than hydroxytyrosol, whereas compounds 1, 5, 6a, 6b, and 8 showed no activity. PMID:24328093

  8. Reactions of OH-radicals with hydroxylated and methoxylated benzoic acids and cinnamic acids. Radiation-induced chemical changes in mushrooms

    International Nuclear Information System (INIS)

    In the first part of this work the radiation induced chemical changes of methoxylated and hydroxylated benzoic acids and cinnamic acids were investigated. Methoxylated compounds were also used as model components for acid derivatives with no free-OH groups. The latter are essentials parts of vegetable foodstuff. A comparison of the radiolytic behaviour of single substituted methoxy- and hydroxybenzoic acids was given at first, data of literature was included. The priority of the investigation was the hydroxylation process induced by OH-radicals. The OH-adduct distribution is generally the same for the hydroxy- as well as for the methoxybenzoic acid isomers. This could be proved by oxidation of these OH-adducts with K3Fe(CN)6. In the presence of air 68-77 % of the hydroxybenzoic acids are converted into hydroxylation products, whereas with the methoxylated acids this reaction leads only to about 10%. An explanation gives the different decay pathways of the intermediate peroxylradical. The multiple methoxy- and hydroxybenzoic acids show three different reaction possibilities: hydroxylation, replacement of -OCH3 by -OH and -in case of the cinnamic acids-oxidative decomposition of the rest of the propenic acid under formation of the corresponding benzaldehydes. All these reactions can be expected when irradiating foodstuff, containing these acid compounds. The characteristic formation of these components and their linear dose/concentrationonents and their linear dose/concentration relationship make these substrates very promising for the use as markers for irradiation treatment of foodstuff. The second part of this work deals with the gamma-radiation induced chemical changes in mushrooms. The irradiated and non-irradiated samples were freeze-dried and purified from matrix components chromatographically on polyamid columns. In case of the phenolic compounds for 4-hydroxybenzoic acid and three unknown components linear dose/concentration relationships could be obtained. Two of these unknown compounds seem to be promising for a use as marker for irradiation treatment of mushrooms. (author)

  9. Reactions of amino acids, peptides, and proteins with oxidized metabolites of tris(p-carboxyltetrathiaaryl)methyl radical EPR probes.

    Science.gov (United States)

    Decroos, Christophe; Boucher, Jean-Luc; Mansuy, Daniel; Xu-Li, Yun

    2014-04-21

    Oxidation of the tris(p-carboxyltetrathiaaryl)methyl (TAM) EPR radical probe, TAMa(•), by rat liver microsomes (RLM) + NADPH, or horseradish peroxidase (HRP) + H2O2, or K2IrCl6, led to an intermediate cation, TAMa(+), which was treated with glutathione (GSH), with formation of an adduct, TAMa-SG(•), resulting from the substitution of a TAMa(•) carboxylate group with the SG group. L-?-Amino acids containing a strong nucleophilic residue (NuH), such as L-cysteine or L-histidine, also reacted with TAMa(+), with formation of radical adducts TAMa-Nu(•) in which a carboxylate group of TAMa(•) was replaced with Nu. Other less nucleophilic L-?-amino acids, such as L-arginine, L-serine, L-threonine, L-tyrosine, or L-aspartate, as well as the tetrapeptide H-(Gly)4-OH, reacted with TAMa(+) via their ?-NH2 group, with formation of an iminoquinone methide, IQMa, deriving from an oxidative decarboxylation and amination of TAMa(•). Upon reaction of TAMa(+) with L-proline and L-lysine, N-substituted iminoquinone methide adducts, IQMa-Pro and IQMa-Lys, were formed. Finally, preliminary results showed that oxidation of TAMa(•) in the presence of bovine serum albumin (BSA), led to the covalent binding of TAMa-derived metabolites to BSA. Oxidation of another frequently used TAM probe, TAMb(•) (Oxo63), in the presence of GSH, N-acetyl-cysteine methyl ester, or histidine also led to TAMb-Nu(•) adducts equivalent to the corresponding TAMa-Nu(•) adducts, suggesting that the oxidative metabolism of such TAM(•) probes could lead to protein covalent binding. Moreover, the above data describe an easy access to new TAM radical EPR probes coupled to amino acids, peptides or proteins that could be useful for addressing various biological targets. PMID:24564180

  10. ?-Alkynyl lipid surrogates for polyunsaturated fatty acids: free radical and enzymatic oxidations.

    Science.gov (United States)

    Beavers, William N; Serwa, Remigiusz; Shimozu, Yuki; Tallman, Keri A; Vaught, Melissa; Dalvie, Esha D; Marnett, Lawrence J; Porter, Ned A

    2014-08-13

    Lipid and lipid metabolite profiling are important parameters in understanding the pathogenesis of many diseases. Alkynylated polyunsaturated fatty acids are potentially useful probes for tracking the fate of fatty acid metabolites. The nonenzymatic and enzymatic oxidations of ?-alkynyl linoleic acid and ?-alkynyl arachidonic acid were compared to that of linoleic and arachidonic acid. There was no detectable difference in the primary products of nonenzymatic oxidation, which comprised cis,trans-hydroxy fatty acids. Similar hydroxy fatty acid products were formed when ?-alkynyl linoleic acid and ?-alkynyl arachidonic acid were reacted with lipoxygenase enzymes that introduce oxygen at different positions in the carbon chains. The rates of oxidation of ?-alkynylated fatty acids were reduced compared to those of the natural fatty acids. Cyclooxygenase-1 and -2 did not oxidize alkynyl linoleic but efficiently oxidized alkynyl arachidonic acid. The products were identified as alkynyl 11-hydroxy-eicosatetraenoic acid, alkynyl 11-hydroxy-8,9-epoxy-eicosatrienoic acid, and alkynyl prostaglandins. This deviation from the metabolic profile of arachidonic acid may limit the utility of alkynyl arachidonic acid in the tracking of cyclooxygenase-based lipid oxidation. The formation of alkynyl 11-hydroxy-8,9-epoxy-eicosatrienoic acid compared to alkynyl prostaglandins suggests that the ?-alkyne group causes a conformational change in the fatty acid bound to the enzyme, which reduces the efficiency of cyclization of dioxalanyl intermediates to endoperoxide intermediates. Overall, ?-alkynyl linoleic acid and ?-alkynyl arachidonic acid appear to be metabolically competent surrogates for tracking the fate of polyunsaturated fatty acids when looking at models involving autoxidation and oxidation by lipoxygenases. PMID:25034362

  11. Spectroscopic studies on the antioxidant activity of ellagic acid

    Science.gov (United States)

    Kilic, Ismail; Ye?ilo?lu, Ye?im; Bayrak, Yüksel

    2014-09-01

    Ellagic acid (EA, C14H6O8) is a natural dietary polyphenol whose benefits in a variety of diseases shown in epidemiological and experimental studies involve anti-inflammation, anti-proliferation, anti-angiogenesis, anticarcinogenesis and anti-oxidation properties. In vitro radical scavenging and antioxidant capacity of EA were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2?-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. EA inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 ?g/mL concentration. On the other hand, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), ?-tocopherol and ascorbic acid displayed 69.8%, 66.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, EA had an effective DPPH• scavenging, ABTSrad + scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, ?-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that EA can be used in the pharmacological, food industry and medicine because of these properties.

  12. Atmospheric aqueous phase radical chemistry of the isoprene oxidation products methacrolein, methyl vinyl ketone, methacrylic acid and acrylic acid--kinetics and product studies.

    Science.gov (United States)

    Schöne, Luisa; Schindelka, Janine; Szeremeta, Edyta; Schaefer, Thomas; Hoffmann, Dirk; Rudzinski, Krzysztof J; Szmigielski, Rafal; Herrmann, Hartmut

    2014-04-01

    Kinetic and mechanistic studies were conducted on the isoprene oxidation products methacrolein, methyl vinyl ketone, methacrylic and acrylic acid reacting with hydroxyl and nitrate radicals and sulfate radical anions in aqueous solution by use of the laser flash photolysis technique and a reversed-rate method for kinetics. High-performance liquid chromatography/mass spectrometry was applied for product analysis. The kinetic investigations show the highest reactivity of the hydroxyl radical followed by sulfate and nitrate radicals. For methacrolein and methyl vinyl ketone the following rate constants have been determined at 298 K: k(OH+methacrolein) = (9.4 ± 0.7) × 10(9) M(-1) s(-1), k(OH+methyl?vinyl?ketone) = (7.3 ± 0.5) × 10(9) M(-1) s(-1), k(NO3+methacrolein) = (4.0 ± 1.0) × 10(7) M(-1) s(-1), k(NO3+methyl?vinyl?ketone) = (9.7 ± 3.4) × 10(6) M(-1) s(-1), k(SO4(-)+methacrolein) = (9.9 ± 4.9) × 10(7) M(-1) s(-1) and k(SO4(-)+methyl?vinyl?ketone) = (1.0 ± 0.2) × 10(8) M(-1) s(-1). Temperature and pH dependencies of the reactions of OH, NO3 and SO4(-) with methacrolein, methyl vinyl ketone, methacrylic and acrylic acid as well as Arrhenius parameters have been obtained and discussed. Product studies were performed on the OH radical induced oxidation of methacrolein and methyl vinyl ketone. In the reaction of methacrolein + OH methylglyoxal and hydroxyacetone were identified as first oxidation products with yields of 0.099 and 0.162. Methylglyoxal was primarily produced in the oxidation of methyl vinyl ketone with a yield of 0.052. For both precursor compounds the formation of glycolaldehyde was observed for the first time with yields of 0.051 and 0.111 in the oxidation of methacrolein and methyl vinyl ketone, respectively. Furthermore, highly functionalised C4 compounds were determined from the oxidation of both precursor compounds, but for the first time for methyl vinyl ketone. Reaction schemes were developed based on known peroxyl radical reaction mechanisms. The aqueous phase conversion of the first generation isoprene oxidation products can potentially contribute to tropospheric aqueous phase budgets of important carbonyl and dicarbonyl components which are expected to be conducive to the formation of aqSOA. PMID:24569503

  13. Block-gradient copolymers of styrene and acrylic acid synthesized by nitroxide-mediated radical polymerization.

    Czech Academy of Sciences Publication Activity Database

    Borisova, O.; Billon, L.; Zaremski, M.; Grassl, B.; Bakaeva, Zulfiya; Lapp, A.; Št?pánek, Petr; Borisov, O.

    Granada : European Polymer Federation, 2011. s. 513. ISBN 978-84-694-3124-5. [European Polymer Congress 2011, Congress of the Specialized Group of Polymers /12./. 26.06.2011-01.07.2011, Granada] Institutional research plan: CEZ:AV0Z40500505 Keywords : block-gradient copolymers * radical polymerization Subject RIV: CD - Macromolecular Chemistry

  14. The ABT Methodology Employment For VET of Quality Auditors

    Directory of Open Access Journals (Sweden)

    Liviu Moldovan

    2011-11-01

    Full Text Available This paper presents some achievements of the project entitled ???Disseminating Open and Innovative Tools and Services for Vocational Education and Training in Quality Assurance??? (acronym Do-IT financed by European Commission. The recent developments and results obtained during pilot testing of new pedagogical models and services, in Do-IT project, targeting engineering education in Romania are presented. This includes the activity Based Training methodology (ABT for quality management system audit course according to ISO 19011 and ISO 9001. ABT focuses on delivering theoretical content linking directly theory and practice according to the industrial production path of an object. The testing of the theoretical and practical achievements has been done using Student Response System (SRS, by using individual voting systems

  15. ESR study of photoinduced free radicals by visible light in hair and the effects of ascorbic acid (vitamin C).

    Science.gov (United States)

    Chikvaidze, E; Khachatryan, I

    2011-08-01

    The ESR spectra of melanin's free radicals in natural black and red hair have been investigated. It is shown that the ESR spectrum of black hair is slightly asymmetric singlet with g=2.0037 and ?H=0.5 mTl. The ESR spectrum of red hair with g=2.0053 differs from the spectrum of black hair. Using the method of saturation was shown that ESR spectrum of red hair represents a superposition of two signals: a singlet, relating to the black hair, and a triplet from red hair's pheomelanin. Under the influence of visible light (blue with ?(max) =450 nm, green with ?(max) =510 nm and red with ?(max) =650 nm) in both types of hair (black and red), the photoinduced free radicals appear, which indicates an increase in the intensity of already existing ESR spectrum of hair. It should be noted that the ESR spectra of red hair from various donors are different. The antioxidant ascorbic acid (vitamin C) has the different effect on the photoinduced free radicals. In particular, in the case of black hair, the concentration of photoinduced free radicals is slightly reduced, whereas in red hair, the disappearance of the triplet in the spectrum is observed, and at the same time, the spectrum becomes a singlet, the intensity of which increases sharply. It is assumed that the antioxidants, effective for black hair, may be ineffective for red hair and vice versa. Therefore, in each, specific case is necessary to investigate the effectiveness of an antioxidant separately. PMID:21284658

  16. Combustion Processes as a Source of High Levels of Indoor Hydroxyl Radicals through the Photolysis of Nitrous Acid.

    Science.gov (United States)

    Bartolomei, V; Gomez Alvarez, E; Wittmer, J; Tlili, S; Strekowski, R; Temime-Roussel, B; Quivet, E; Wortham, H; Zetzsch, C; Kleffmann, J; Gligorovski, S

    2015-06-01

    Hydroxyl radicals (OH) are known to control the oxidative capacity of the atmosphere but their influence on reactivity within indoor environments is believed to be of little importance. Atmospheric direct sources of OH include the photolysis of ozone and nitrous acid (HONO) and the ozonolysis of alkenes. It has been argued that the ultraviolet light fraction of the solar spectrum is largely attenuated within indoor environments, thus, limiting the extent of photolytic OH sources. Conversely, the ozonolysis of alkenes has been suggested as the main pathway of OH formation within indoor settings. According to this hypothesis the indoor OH radical concentrations span in the range of only 10(4) to 10(5) cm(-3). However, recent direct OH radical measurements within a school classroom yielded OH radical peak values at moderate light intensity measured at evenings of 1.8 × 10(6) cm(-3) that were attributed to the photolysis of HONO. In this work, we report results from chamber experiments irradiated with varying light intensities in order to mimic realistic indoor lighting conditions. The exhaust of a burning candle was introduced in the chamber as a typical indoor source causing a sharp peak of HONO, but also of nitrogen oxides (NOx). The photolysis of HONO yields peak OH concentration values, that for the range of indoors lightning conditions were estimated in the range 5.7 ×· 10(6) to 1.6 × 10(7) cm(-3). Excellent agreement exists between OH levels determined by a chemical clock and those calculated by a simple PSS model. These findings suggest that significant OH reactivity takes place at our dwellings and the consequences of this reactivity-that is, formation of secondary oxidants-ought to be studied hereafter. PMID:25942056

  17. The ABT Methodology Employment For VET of Quality Auditors

    OpenAIRE

    Liviu Moldovan

    2011-01-01

    This paper presents some achievements of the project entitled ???Disseminating Open and Innovative Tools and Services for Vocational Education and Training in Quality Assurance??? (acronym Do-IT) financed by European Commission. The recent developments and results obtained during pilot testing of new pedagogical models and services, in Do-IT project, targeting engineering education in Romania are presented. This includes the activity Based Training methodology (ABT) for quality management sys...

  18. Radical S-adenosyl methionine epimerases: regioselective introduction of diverse D-amino acid patterns into peptide natural products.

    Science.gov (United States)

    Morinaka, Brandon I; Vagstad, Anna L; Helf, Maximilian J; Gugger, Muriel; Kegler, Carsten; Freeman, Michael F; Bode, Helge B; Piel, Jörn

    2014-08-01

    PoyD is a radical S-adenosyl methionine epimerase that introduces multiple D-configured amino acids at alternating positions into the highly complex marine peptides polytheonamide A and B. This novel post-translational modification contributes to the ability of the polytheonamides to form unimolecular minimalistic ion channels and its cytotoxic activity at picomolar levels. Using a genome mining approach we have identified additional PoyD homologues in various bacteria. Three enzymes were expressed in E. coli with their cognate as well as engineered peptide precursors and shown to introduce diverse D-amino acid patterns into all-L peptides. The data reveal a family of architecturally and functionally distinct enzymes that exhibit high regioselectivity, substrate promiscuity, and irreversible action and thus provide attractive opportunities for peptide engineering. PMID:24943072

  19. Tropospheric chemistry of natural hydrocarbons, aldehydes, and peroxy radicals: Their connections to sulfuric acid production and climate effects

    International Nuclear Information System (INIS)

    Recent work has shown that natural hydrocarbon emissions can significantly affect the levels of urban and regional tropospheric ozone. We report on the reactivities of these biogenic trace gases, particularly isoprene, focusing on their importance in the production of aldehydes and peroxy radicals, leading to increased levels of hydrogen over regional forests. Hydrogen peroxide can lead to the wet oxidation of sulfur dioxide to acidic sulfate in aerosols, fogs, and clouds. In turn, acidic sulfate can act to as a light scattering aerosol and a source of cloud condensation nuclei (CCN), potentially leading to global cooling. Aerosol sulfate and other dissolved organic and inorganic compounds can also play important roles as a greenhouse species in the lower troposphere

  20. Comparison of the capacities of the perhydroxyl and the superoxide radicals to initiate chain oxidation of linoleic acid

    International Nuclear Information System (INIS)

    Since data are accumulating that seem to dispute the role of O2- as a potent agent of biological damage, a study of the previously ignored conjugate acid, the perhydroxyl radical (HO2), a transient species always formed in the presence of O2- in H2O, was undertaken. The results of the systematic studies of the reaction rates of HO2/O2- with a number of biochemicals as a function of pH are tabulated. The data indicated that HO2 reacts faster than O2- with all of the compounds, and the reaction conditions are such that its presence is always assured. The reaction of HO2 with linoleic acid (a C18 unsaturated fatty acid with 2 double bonds) was studied in detail using HO2 formed from O2- generated by photolysis of oxygenated alkaline ethanol solutions in a special apparatus previously described. The present work does not answer the question whether the oxidation of linoleic acid and probably other polyunsaturated fatty acids by HO2 can lead to biological damage, but it can be assumed now that the most obvious sites for damage are the plasma and intracellular membranes

  1. Reactivity of OH radicals with chlorobenzoic acids-A pulse radiolysis and steady-state radiolysis study

    DEFF Research Database (Denmark)

    Zona, Robert; Solar, Sonja

    2010-01-01

    The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k(OH+substrates)=(4.5?6.2)×109 dm3 mol?1 s?1, have been studied by pulse radiolysis in N2O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320?340 nm. Their decay was according to a second-order reaction, 2k=(1?9)×108 dm3 mol?1 s?1. In the presence of N2O/O2 the formation of peroxyl radicals was detectable for 2-, 4-ClBzA and ClBz, k(OH-adduct+O2)=(2?4)×107 dm3 mol?1 s?1, while this reaction for 3-ClBzA was too slow to be registered. In the presence of N2O the degradation rates induced by gamma radiation were very similar for all chlorobenzoic acids, yet the chloride formation was distinctly higher for 3-ClBzA. In the presence of oxygen the initial degradation of 2-and 4-ClBzA equaled the OH-radical concentration, whereas in case of 3-ClBzA only 60% of OH led to degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out.

  2. Reactivity of OH radicals with chlorobenzoic acids-A pulse radiolysis and steady-state radiolysis study

    Energy Technology Data Exchange (ETDEWEB)

    Zona, Robert [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Solar, Sonja, E-mail: sonja.solar@univie.ac.a [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Getoff, Nikola [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Sehested, Knud; Holcman, Jerzy [RISO National Laboratory Environmental Science and Technology Department, DK-4000, Roskilde (Denmark)

    2010-05-15

    The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k({sup c}entre dotOH+substrates)=(4.5-6.2)x10{sup 9} dm{sup 3} mol{sup -1} s{sup -1}, have been studied by pulse radiolysis in N{sub 2}O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320-340 nm. Their decay was according to a second-order reaction, 2k=(1-9)x10{sup 8} dm{sup 3} mol{sup -1} s{sup -1}. In the presence of N{sub 2}O/O{sub 2} the formation of peroxyl radicals was detectable for 2-, 4-ClBzA and ClBz, k(OH-adduct+O{sub 2})=(2-4)x10{sup 7} dm{sup 3} mol{sup -1} s{sup -1}, while this reaction for 3-ClBzA was too slow to be registered. In the presence of N{sub 2}O the degradation rates induced by gamma radiation were very similar for all chlorobenzoic acids, yet the chloride formation was distinctly higher for 3-ClBzA. In the presence of oxygen the initial degradation of 2-and 4-ClBzA equaled the OH-radical concentration, whereas in case of 3-ClBzA only approx60% of {sup c}entre dotOH led to degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out.

  3. Exploring water catalysis in the reaction of thioformic acid with hydroxyl radical: a global reaction route mapping perspective.

    Science.gov (United States)

    Kaur, Gurpreet; Vikas

    2014-06-12

    Hydrogen abstraction pathways, in the gas-phase reaction of tautomers of thioformic acid (TFA), TFA(thiol), and TFA(thione), with hydroxyl radical in the presence and absence of single water molecule acting as a catalyst, is investigated with high-level quantum mechanical calculations at CCSD(T)/6-311++G(2d,2p)//MP2/6-311++G(2d,2p), CCSD(T)/6-311++G(d,p)//DFT/BHandHLYP/6-311++G(d,p), and DFT/B3LYP/6-311++G(2df,2p) levels of the theory. A systematic and automated search of the potential energy surface (PES) for the reaction pathways is performed using the global reaction route mapping (GRRM) method that employs an uphill walking technique to search prereaction complexes and transition states. The computations reveal significant lowering of the PES and substantial reduction in the activation energy for the hydrogen abstraction pathway in the presence of water, thereby proving water as an efficient catalyst in the reaction of both the TFA tautomers with OH radical. The hydrogen-bonding interactions are observed to be responsible for the large catalytic effect of water. Notably, in the case of TFA(thiol), formyl hydrogen abstraction is observed to be kinetically more favorable, while acidic hydrogen abstraction is observed to be thermodynamically more feasible. Interestingly, in the case of TFA(thione), reaction pathways involving only formyl hydrogen abstraction were observed to be feasible. The water-catalyzed hydrogen abstraction reaction of TFA with hydroxyl radical, investigated in this work, can provide significant insights into the corresponding reaction in the biological systems. PMID:24835635

  4. In-vitro free radical scavenging activity of biosynthesized gold and silver nanoparticles using Prunus armeniaca (apricot) fruit extract

    International Nuclear Information System (INIS)

    In-vitro free radical scavenging activity of biosynthesized gold (Au-NPs) and silver (Ag-NPs) nanoparticles was investigated in the present study. Natural precursor Prunus armeniaca (apricot) fruit extract was used as a reducing agent for the nanoparticle synthesis. The free radical scavenging activity of the nanoparticles were observed by modified 1,1?-diphynyl-2-picrylhydrazyl, DPPH and 2,2?-azinobis (3-ethylbenzothiazoline-6-sulfonic acid), ABTS assay. The synthesized nanoparticles were characterized by UV–Visible spectroscopy, dynamic light scattering, transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectroscopy, and fourier transform infrared spectroscopy (FTIR). Appearance of optical absorption peak at 537 nm (2.20 keV) and 435 nm (3 keV) within 0.08 and 0.5 h of reaction time was confirmed the presence of metallic Au and Ag nanoclusters, respectively. Nearly spherical nanoparticles with majority of particle below 20 nm (TEM) for both Au-NPs and Ag-NPs were synthesized. XRD pattern confirmed the existence of pure nanocrystalline Au-NPs while few additional peaks in the vicinity of fcc silver-speculated crystallization of metalloproteins of fruit extract on the surface of the Ag-NPs and vice versa. FTIR spectra was supported the role of amino acids of protein/enzymes of fruit extract for synthesis and stabilization of nanoparticles. Dose-dependent scavenging activity was observed for Au-NPs and Ag-NPs in both DPPH and ABTSNPs and Ag-NPs in both DPPH and ABTS in-vitro assay. 50 % scavenging activity for DPPH were 11.27 and 16.18 mg and for ABTS 3.40 and 7.12 mg with Au-NPs and Ag-NPs, respectively.

  5. In-vitro free radical scavenging activity of biosynthesized gold and silver nanoparticles using Prunus armeniaca (apricot) fruit extract

    Energy Technology Data Exchange (ETDEWEB)

    Dauthal, Preeti; Mukhopadhyay, Mausumi, E-mail: mausumi_mukhopadhyay@yahoo.com [S.V. National Institute of Technology, Department of Chemical Engineering (India)

    2013-01-15

    In-vitro free radical scavenging activity of biosynthesized gold (Au-NPs) and silver (Ag-NPs) nanoparticles was investigated in the present study. Natural precursor Prunus armeniaca (apricot) fruit extract was used as a reducing agent for the nanoparticle synthesis. The free radical scavenging activity of the nanoparticles were observed by modified 1,1 Prime -diphynyl-2-picrylhydrazyl, DPPH and 2,2 Prime -azinobis (3-ethylbenzothiazoline-6-sulfonic acid), ABTS assay. The synthesized nanoparticles were characterized by UV-Visible spectroscopy, dynamic light scattering, transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectroscopy, and fourier transform infrared spectroscopy (FTIR). Appearance of optical absorption peak at 537 nm (2.20 keV) and 435 nm (3 keV) within 0.08 and 0.5 h of reaction time was confirmed the presence of metallic Au and Ag nanoclusters, respectively. Nearly spherical nanoparticles with majority of particle below 20 nm (TEM) for both Au-NPs and Ag-NPs were synthesized. XRD pattern confirmed the existence of pure nanocrystalline Au-NPs while few additional peaks in the vicinity of fcc silver-speculated crystallization of metalloproteins of fruit extract on the surface of the Ag-NPs and vice versa. FTIR spectra was supported the role of amino acids of protein/enzymes of fruit extract for synthesis and stabilization of nanoparticles. Dose-dependent scavenging activity was observed for Au-NPs and Ag-NPs in both DPPH and ABTS in-vitro assay. 50 % scavenging activity for DPPH were 11.27 and 16.18 mg and for ABTS 3.40 and 7.12 mg with Au-NPs and Ag-NPs, respectively.

  6. Oxidation by a reagent H2O2-vanadium complex-pyrazine-2-carboxylic acid. 3. Evidence for hydroxyl radical formation

    International Nuclear Information System (INIS)

    Evidence for the formation of hydroxyl radicals and their participation in the hydrocarbon oxidation by a reagent H2O2-vanadium complex-pyrazine-2-carboxylic acid has been obtained by two different routes: by the application of spin trapping and kinetically by the competitive oxidation of a mixture benzene-aliphatic alcohol. The suggestion has been made that the hydroxyl radicals generate in the reaction of vanadium complex (Bu4N)VO3 with hydrogen peroxide. 22 refs.; 1 fig

  7. In vitro release of arachidonic acid metabolites, glutathione peroxidase, and oxygen-free radicals from platelets of asthmatic patients with and without aspirin intolerance.

    OpenAIRE

    Plaza, V; Prat, J; Rosellò, J.; Ballester, E; Ramis, I; Mullol, J. (J.); Gelpí, E.; Vives-Corrons, J L; Picado, C

    1995-01-01

    BACKGROUND--An abnormal platelet release of oxygen-free radicals has been described in acetylsalicylic acid (aspirin)-induced asthma, a finding which might suggest the existence of an intrinsic, specific platelet abnormality of arachidonic acid metabolism in these patients. The objective of this study was to evaluate platelet arachidonic acid metabolism in asthmatic patients with or without intolerance to aspirin. METHODS--Thirty subjects distributed into three groups were studied: group 1, 1...

  8. Biological Activities of Hominis Placenta Herbal Acupuncture prepared by Hydrochloric Acid Hydrolysis

    Directory of Open Access Journals (Sweden)

    Geun-young Seo

    2010-06-01

    Full Text Available Reactive Oxygen Species(ROS are continuously produced at a high rate as a by-product of aerobic metabolism. Since tissue damage by free radical increases with age, the reactive oxygen species(ROS such as hydrogen peroxide(H2O2, nitric oxide(NO. Several lines of evidence provided that ROS appears to cause to develop aging-related various diseases such as cancer, arthritis, cardiovascular disease. In this study, we have conducted to investigate the biological activities of Hominis Placenta Herbal Acupuncture by measuring total polyphenol content, DPPH radical scavenging, ABTS radical scavenging, Superoxide dismutase(SOD-like activity, Nitrite scavenging ability in vitro. The total polyphenol contents of Hominis Placenta Herbal Acupuncture was 24.6?/?. Elctron donation ability on DPPH was 49.4%. The 2,2'-azinobis-3-ehtlbezothiazoline-6-sulfonic acid radical decolorization (ABTS was 50.01%, similar to the DPPH free radical scavenging. The superoxide dismutase (SOD-like activities of hominis placenta herbal acupuncture was 50.876%. The nitrite scavenging abilities at pH 1.5, pH 3.0, pH 6.0 were 52.8%, 29.4%, 15.4%, respectively; these abilities decreased as pH increased. We conclude that Hominis Placenta Herbal Acupuncture may be useful as potential sources of antioxidant.

  9. Radical Scavenging Activity of the Essential Oil of Silver Fir (Abies alba).

    Science.gov (United States)

    Yang, Seun-Ah; Jeon, Sang-Kyung; Lee, Eun-Jung; Im, Nam-Kyung; Jhee, Kwang-Hwan; Lee, Sam-Pin; Lee, In-Seon

    2009-05-01

    The essential oil of silver fir (Abies alba) is known to help respiratory system and have easing and soothing effect for muscle. In the present study, we investigated the chemical composition, cytotoxicity and its biological activities of silver fir (Abies alba) essential oil. The composition of the oil was analyzed by GC-MS and bornyl acetate (30.31%), camphene (19.81%), 3-carene (13.85%), tricyclene (12.90%), dl-limonene (7.50%), alpha-pinene (2.87%), caryophyllene (2.18%), beta-phellandrene (2.13%), borneol (1.74%), bicyclo[2.2.1]hept-2-ene,2,3-dimethyl (1.64%) and alpha-terpinene (1.24%) were the major components in the oil. The results tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay indicated that the oil showed no cytotoxic effect, at concentrations of 1 and 5%, for as long as 24 and 3 h, respectively. The antiradical capacity was evaluated by measuring the scavenging activity of the essential oil on the 2,20-diphenylpicrylhydrazyl (DPPH) and 2,2'-azino-bis 3-ethyl benzothiazoline-6-sulfonic acid (ABTS) radicals. The oil was able to reduce the both radicals dose-dependently, and the concentration required for 50% reduction (RC(50)) against DPPH radicals (2.7 +/- 0.63%) was lower than ABTS radicals (8.5 +/- 0.27%). The antibacterial activity of the oil was also evaluated using disc diffusion method against Staphylococcus aureus, Streptococcus mutans, Listeria monocytogenes, Acinetobacter baumannii, Escherichia coli, and Vibrio parahaemolyticcus. The oil exhibited no antibacterial activity against all the bacterial strains tested except S. aureus of mild activity. PMID:19430614

  10. Peroxyacetic acid in urban and rural atmosphere: concentration, feedback on PAN-NOx cycle and implication on radical chemistry

    Directory of Open Access Journals (Sweden)

    J. L. Li

    2010-01-01

    Full Text Available Peroxyacetic acid (PAA is one of the most important atmospheric organic peroxides, which have received increasing attention for their potential contribution to the oxidation capacity of the troposphere and the formation of secondary aerosols. We report here, for the first time, a series of data for atmospheric PAA concentrations at urban and rural sites, from five field campaigns carried out in China in summer 2006, 2007 and 2008. For these five measurements, daytime mean (08:00–20:00 LT PAA concentrations on sunlit days were 21.4–148.0 pptv with a maximum level of ~1 ppbv. The various meteorological and chemical parameters influencing PAA concentrations were examined using Principal Factor Analysis. This statistical analysis shows that the local photochemical production was the major source of PAA, and its concentration increased with increasing temperature, solar radiation and ozone but decreased with increasing NOx (NO and NO2, CO, SO2, and relative humidity. Based on the dataset, several issues are highlighted in this study: (i Because PAA is a product from the photochemical oxidation of some specific volatile organic compounds (VOCs that lead to acetyl peroxy radicals, the importance of various VOCs with respect to the PAA formation is therefore ranked using the incremental reactivity method. (ii The contribution of PAN thermal degradation to PAA formation under conditions of different NOx concentrations is estimated based on the chemical kinetics analysis. The result shows that PAN seems to play an important role in the formation of PAA when the NO/NO2 concentration ratio was less than 0.2 and PAA would correspondingly have feedback on the PAN-NOx cycle. (iii PAA and other peroxides, such as methyl hydroperoxide (MHP and H2O2, usually exhibited a similar asymmetric shape typically shifted to the afternoon. However, under some conditions, H2O2 diurnal cycle was out of phase with MHP and PAA. The combination of linear regression and kinetics analysis indicate that the formation and removal processes of H2O2 may be different from those of MHP and PAA. (iv Considering that PAA is the reservior of free radicals, its fate is expected to have an effect on the free radical budget in the atmosphere. A box model based on the CBM-IV mechanism has been performed to access its influence on the radical budget. We suggest that the detailed information on PAA in the atmosphere is of importance to better understand the free radical chemistry.

  11. Peroxyacetic acid in urban and rural atmosphere: concentration, feedback on PAN-NOx cycle and implication on radical chemistry

    Directory of Open Access Journals (Sweden)

    J. L. Li

    2009-10-01

    Full Text Available Peroxyacetic Acid (PAA is one of important atmospheric organic peroxides, which have received increasing attention for their potential contribution to the oxidation capacity of the troposphere and the formation of secondary aerosols. We report here that, for the first time, a series of data for atmospheric PAA concentrations at urban and rural sites, from five field campaigns carried out in China in summer 2006, 2007 and 2008. For these five measurements, daytime mean PAA concentrations on sunlit days were 0.02–0.14 ppbv with a maximum level of ~1 ppbv. The various meteorological and chemical parameters influencing PAA concentrations were examined using the Principal Factor Analysis. This statistical analysis shows that the local photochemical production was the major source of PAA, and its concentration increased with increasing temperature, solar radiation and ozone but decreased with increasing NOx (NO and NO2, CO, SO2, and relative humidity. Based on the dataset, several issues are highlighted in this study: (i because PAA is a product from the photochemical oxidation of some specific volatile organic compounds (VOCs that lead to acetyl peroxy radicals, the importance of various VOCs with respect to the PAA formation is therefore ranked using the incremental reactivity method. (ii The contribution of PAN thermal degradation to PAA formation under conditions of different NOx concentrations is estimated based on the chemical kinetics analysis. The result shows that PAN seems to play an important role in the formation of PAA when the NO/NO2 concentration ratio was less than 0.2 and PAA would correspondingly have feedback on the PAN-NOx cycle. (iii PAA and other peroxides, such as methyl hydroperoxide (MHP and H2O2, usually exhibited a similar asymmetric shape typically shifted to the afternoon. However, at a high SO2 level, H2O2 showed a profile different from those of MHP and PAA. The combination of linear regression and chemical kinetics analysis reveals that a possible unknown pathway results in the significant removal of H2O2 and the extent of H2O2 undergoing this pathway needs a further study. (iv Considering that PAA is the reservior of free radicals, its fate is expected to have an effect on the free radical budget in the atmosphere. A box model based on the CBM-IV mechanism has been performed to access its influence on the radical budget. We suggest that the detailed information on PAA in the atmosphere is of importance to better understand the free radical chemistry.

  12. Phytochemical analysis and in vitro free-radical-scavenging activities of the essential oils from leaf and fruit of Melaleuca leucadendra L.

    Science.gov (United States)

    Pino, Jorge A; Regalado, Erik L; Rodríguez, José L; Fernández, Miguel D

    2010-09-01

    The phytochemical profile of Melaleuca leucadendra L. leaf and fruit oils from Cuba was investigated by GC and GC/MS. Forty-one and sixty-four volatile compounds were identified and quantified, accounting for 99.2 and 99.5% of the leaf-oil and fruit-oil total composition, respectively. The main components were 1,8-cineol (43.0%), viridiflorol (24.2%), ?-terpineol (7.0%), ?-pinene (5.3%), and limonene (4.8%) in the leaf oil, and viridiflorol (47.6%), globulol (5.8%), guaiol (5.3%), and ?-pinene (4.5%) in the fruit oil. The antioxidant capacity of these essential oils was determined by three different in vitro assays (2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, thiobarbituric acid reactive species (TBARS), and 2,2'-Azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation), and significant activities were evidenced for all of them. PMID:20860029

  13. Chemical composition of the essential oil of Ligularia hodgsonii and free radical scavenging activity of the oil and crude extracts.

    Science.gov (United States)

    Zhou, Zihao; Tang, Jun; Song, Xueping

    2014-10-01

    The chemical composition of the essential oil from roots and rhizomes of Ligularia hodgsonii was analyzed by gas chromatography (GC) and GC-mass spectrometry (MS). Forty-seven components were identified, representing 77.0% of the total oil. The main constituents were l-(+)-ascorbic acid 2,6- dihexadecanoate (15.7%), selina-6-en-4-ol (8.4%) and 9,10-dimethyl-1,2,3,4,5,6,7,8-octahydroanthracene (6.6%). The free radical scavenging activities of the essential oil, aqueous extract, ethanolic extract, and crude polysaccharides of L. hodgsonii, as well as some of their major components, were investigated using DPPH and ABTS assays. The essential oil displayed a lower capacity to quench free radicals than the extracts; the ethanolic and aqueous extracts showed considerably higher antioxidant potential that deserves further study. PMID:25522549

  14. A mechanism for NaCl inhibition of Reactive Blue 19 decolorization and ABTS oxidation by laccase.

    Science.gov (United States)

    Champagne, P-P; Nesheim, M E; Ramsay, J A

    2013-07-01

    Laccases produced by white rot fungi have been extensively evaluated for their potential to decolorize textile wastewaters which contain salts like sodium chloride and sodium sulfate. The effect of sodium chloride and sodium sulfate on Trametes versicolor laccase during the decolorization of an anthraquinone dye (Reactive Blue 19) and the oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) were evaluated by steady-state kinetic analysis. The results showed that, while sodium sulfate did not affect laccase activity, sodium chloride inhibited both ABTS oxidation and dye decolorization. However, the type of inhibition was substrate-dependent: it was hyperbolic, noncompetitive with ABTS and parabolic, noncompetitive with Reactive Blue 19. Furthermore, the results suggested that two chlorides may bind to laccase in the presence of the dye unlike recent inhibition models which suggest that there is only one inhibition site. This investigation is the first to provide evidence for and to propose a two-site model of laccase inhibition, providing new insight into NaCl inhibition of laccase. The proposed model is also useful to predict decolorization rates in the presence of sodium chloride and to determine operating conditions that will minimize inhibition. PMID:23129183

  15. Free Radical Reactions in Food.

    Science.gov (United States)

    Taub, Irwin A.

    1984-01-01

    Discusses reactions of free radicals that determine the chemistry of many fresh, processed, and stored foods. Focuses on reactions involving ascorbic acid, myoglobin, and palmitate radicals as representative radicals derived from a vitamin, metallo-protein, and saturated lipid. Basic concepts related to free radical structure, formation, and…

  16. Evaluation of free-radical quenching properties of standard Ayurvedic formulation Vayasthapana Rasayana

    Directory of Open Access Journals (Sweden)

    Bhujbal Akshay

    2011-05-01

    Full Text Available Abstract Background Cellular damage induced by free-radicals like Reactive Oxygen and Nitrogen Species (ROS and RNS has been implicated in several disorders and diseases, including ageing. Hence naturally occurring anti-oxidant rich-herbs play a vital role in combating these conditions. The present study was carried out to investigate the in vitro free-radical quenching capacity of a known Ayurvedic poly-herbal formulation called Vayasthapana Rasayana. Methods Methanol extracts of Vayasthapana Rasayana formulation (VRF were studied for in vitro total antioxidant activity along with phenolic content and reducing power. In vitro assays like DPPH, FRAP, ABTS scavenging to evaluate radical quenching potential were performed. Results The formulation has shown 94% at 0.1 mg/ml DPPH free-radical scavenging activity as against 84% at 0.1 mg/ml for standard ascorbic acid (IC50 value 5.51 ?g/ml for VRF and 39 ?g/ml for standard. It has a significant higher ferric reducing potential also (OD 0.87 at 700 nm & 0.21 at 0.1 mg/ml for VRF and standard, respectively. The total phenolic content (gallic acid equivalent of the VRF is 8.3 mg per g of dry mass. Total antioxidant capacity of the formulation, estimated by FRAP was 1150 ± 5 ?M Fe(II/g dry mass. ABTS radical scavenging activity of VRF was 69.55 ± 0.21% at 100 ?g/ml concentration with a IC50 value of 69.87 ?g/ml as against 9% and 95% by ascorbic acid and Trolox (at 70.452 ?g/ml and 0.250 ?g/ml concentrations, respectively. Conclusion In Indian traditional Ayurvedic system, use of VRF is in regular practice for mainly combating age-related disorders and diseases as many of the components of the Rasayana are known for their free-radical scavenging activity. This study has validated the potential use of VRF as an anti-oxidant to fight age-related problems.

  17. The ABT methodology employment for VET of quality auditors

    Directory of Open Access Journals (Sweden)

    Liviu Moldovan

    2011-12-01

    Full Text Available This paper presents some achievements of the project entitled “Disseminating Open and Innovative Tools and Services for Vocational Education and Training in Quality Assurance” (acronym Do-IT financed by European Commission. The recent developments and results obtained during pilot testing of new pedagogical models and services, in Do-IT project, targeting engineering education in Romania are presented. This include the activity Based Training methodology (ABT for quality management system audit course according to ISO 19011 and ISO 9001 and evaluation of theoretical achievements with Student Response System (SRS.

  18. Vinblastine rapidly induces NOXA and acutely sensitizes primary chronic lymphocytic leukemia cells to ABT-737

    OpenAIRE

    Bates, Darcy J. P.; Danilov, Alexey V.; Lowrey, Christopher H.; Eastman, Alan

    2013-01-01

    Proteins of the BCL2 family provide a survival mechanism in many human malignancies including chronic lymphocytic leukemia (CLL). The BCL2 inhibitor ABT-263 (navitoclax) is active in clinical trials for lymphoid malignancies, yet resistance is expected based on preclinical models. We recently demonstrated that vinblastine can dramatically sensitize several leukemia cell lines to ABT-737 (the experimental congener of ABT-263). The goal of these experiments was to determine the impact of vinbla...

  19. Pulse radiolytic and product analysis studies of the reaction of hydroxyl radicals with cinnamic acid. The relative extent of addition to the ring and side chain

    International Nuclear Information System (INIS)

    Using pulse radiolysis with optical detection and high-pressure liquid chromatography (HPCL), it has been shown that reaction of OH radicals with cinnamic acid (CA in aqueous solutions leads to addition to both the ring and the olefinic group. The relative extent of the above two pathways was estimated as 3:7, respectively. Benzyl- and hydroxycyclohexadienyl-type radicals were observed with absorption maxima at 320 (310) and 370 (365) nm depending on the pH of the solution. In the pH region 4.9 to 5.7 the absorption at 305 to 315 nm decays during the first 5 ?s after the pulse. The dependence of the rate constants and absorption spectra on pH suggests that this decay is due to an equilibration process between acid-base forms of benzyl-type radicals formed through OH addition to te olefinic group

  20. Vinblastine rapidly induces NOXA and acutely sensitizes primary chronic lymphocytic leukemia cells to ABT-737.

    Science.gov (United States)

    Bates, Darcy J P; Danilov, Alexey V; Lowrey, Christopher H; Eastman, Alan

    2013-08-01

    Proteins of the BCL2 family provide a survival mechanism in many human malignancies, including chronic lymphocytic leukemia (CLL). The BCL2 inhibitor ABT-263 (navitoclax) is active in clinical trials for lymphoid malignancies, yet resistance is expected on the basis of preclinical models. We recently showed that vinblastine can dramatically sensitize several leukemia cell lines to ABT-737 (the experimental congener of ABT-263). The goal of these experiments was to determine the impact of vinblastine on ABT-737 sensitivity in CLL cells isolated from peripheral blood and to define the underlying mechanism. Freshly isolated CLL cells from 35 patients, as well as normal lymphocytes and platelets, were incubated with various microtubule-disrupting agents plus ABT-737 to assess sensitivity to the single agents and the combination. ABT-737 and vinblastine displayed a range of sensitivity as single agents, and vinblastine markedly sensitized all CLL samples to ABT-737 within six hours. Vinblastine potently induced the proapoptotic protein PMAIP1 (NOXA) in both time- and dose-dependent manner and this was required for the observed apoptosis. Combretastatin A4, which dissociates microtubules by binding to a different site, had the same effect, confirming that interaction of these agents with microtubules is the initial target. Similarly, vincristine and vinorelbine induced NOXA and enhanced CLL sensitivity to ABT-737. Furthermore, vinblastine plus ABT-737 overcame stroma-mediated resistance to ABT-737 alone. Apoptosis was induced with clinically achievable concentrations with no additional toxicity to normal lymphocytes or platelets. These results suggest that vinca alkaloids may improve the clinical efficacy of ABT-263 in patients with CLL. PMID:23723123

  1. Syntheses, structural characterization, and DPPH radical scavenging activity of cocrystals of caffeine with 1- and 2-naphthoxyacetic acids

    Science.gov (United States)

    Suresh Kumar, G. S.; Seethalakshmi, P. G.; Sumathi, D.; Bhuvanesh, N.; Kumaresan, S.

    2013-03-01

    Caffeine:1-naphthoxyacetic acid [(caf)(1-naa)] and caffeine:2-naphthoxyacetic acid [(caf)(2-naa)] cocrystals have been synthesized and single crystals were grown by slow evaporation technique. The structures of the grown crystals were elucidated using single crystal X-ray diffraction analysis. Both the cocrystals belong to the monoclinic crystallographic system with space group P21/c, Z = 4, and ? = ? = 90°, whereas ? = 111.4244(18)° for [(caf)(1-naa)] and ? = 109.281(6)° for [(caf)(2-naa)]. The crystal packing is predominantly stabilized by hydrogen bonding and ?-? stacking interactions. The presence of unionized -COOH functional group in both the cocrystals was identified by FTIR spectral analysis. Thermal behavior and stability of both the cocrystals were studied by TGA/DTA analyses. Solvent-free formation of these cocrystals was confirmed by powder X-ray diffraction analyses. The theoretical energy of cocrystals showed that the formers have higher energy than cocrystals 1 and 2. DPPH radical scavenging activity of cocrystals 1 and 2 is slightly greater than the formers.

  2. Rate constants for the reactions of halogenated organic radicals

    International Nuclear Information System (INIS)

    Absolute rate constants have been measured by means of pulse radiolysis for the reactions of various halogenated aliphatic compounds (ethane derivatives, including the anaesthetics halothane, enflurane, isoflurane and methoxyflurane) with hydrated electrons and OH anion radicals, the reactions of halogenated carbon-centred radicals, derived thereby, with molecular oxygen, and the reactions of halogenated peroxyl radicals with various antioxidants (ascorbate, chlorpromazine promethazine, propyl gallate, ABTS) in aqueous solutions. All oxygen addition reactions occur essentially diffusion-controlled. This finding is correlated with the stereoelectronic properties of the primary carbon-centred radicals. The oxidative power of the halogenated peroxyl radicals reflects the inductive-l effect of the halogens and accordingly increases with the degree of halogen substitution, with fluorine substituents being particularly effective. The peroxyl radicals derived from freon 113, namely CClF2CClFOO radical and CCl2FCF2OO radical, have been identified as the best oxidants among these species. (author)

  3. Reaction rates of hydroxyl radical with nitric acid and with hydrogen peroxide

    International Nuclear Information System (INIS)

    The rates of the reactions HO+HNO3 ? H2O+NO3, (1), HO+H2O2 ? H2O+HOO (2) have been studied by laser flash photolysis of reactants and resonance fluorescence of hydroxyl radicals. The recently reported high rate constants at room temperature for both reactions and the negative activation energy for Reaction (1) at low temperature have been confirmed. Results obtained here are: k1 = 1.52 x 10-14 exp(644/T) cm3 molecule-1 s-1 from 218--363 K and k2 = 1.81 x 10-12 cm3 molecule-1 s-1 at 298 K. These two reactions have been examined by transition-state theory; (1) is assigned a cyclic and (2) a chainlike transition state. Even with no potential energy barrier, the reaction coordinate of (1) involves a quantum-mechanical, temperature independent frequency; and with this model the low pre-exponential factor and negative activation energy of Reaction (1) can be explained

  4. The structure and properties of free radicals: An electron spin resonance study of radiation damage to nucleic acid and protein components and to some sulfur-substituted derivitives

    International Nuclear Information System (INIS)

    When cellular systems are exposed to ionizing radiation the long-term effects may range from minor disturbances to such dramatic changes as mutations and cell death. The processes leading to these macroscopical injuries are primarily confined at the molecular level. In all models aimed at a description of the action of radiation at the molecular level the formation of free radicals (which are species containing unpaired electrons) is a central concept. The technique of ESR spectroscopy is uniquely suited to study free radicals, as it is based on resonance absorption of energy by unpaired electrons in a magnetic field. ESR spectroscopy makes it possible to detect free radicals and, in some cases, to identify them. In order to study free radicals by ESR it is necessary to build up a sufficient number of unpaired spins in the sample (approximately 1011 or more, depending on the shape of the resonance). This may be different techniques have been used to trap the induced radicals or to attain a sufficient steady state concentration level. A procedure which seems to contain a large amount of information is to irradiate at low temperatures, and, by subsequent heat-treatment of the sample to study the reactions and fate of the induced radicals. In this thesis single crystal studies of aromatic amino acids and pyrimidine derivitives together with some substituted purine derivitives are presented, and the results are discussed in relation to the present knowledge about radical formation in these classes of compounds. Single crystal studies of some sulfur-containing aromatic compounds have been presented with the purpose of shedding light on the electronic structure of sulfur-centred radicals. (JIW)

  5. About formation of radicals by the photolysis of uranyl salts in aliphatic carbon acids

    International Nuclear Information System (INIS)

    The photolysis of UO2(NO3)2x6H2O and UO2(RCOO)2 (R=CH3, C2H5, C3H7, and CH(CH3)2) has been studied by ESR spin trapping technique using nitrosodurene as a spin trap. Evidences for electron transfer from both coordinated anions and carboxylic acid to U(VI) were found. (author)

  6. Free radical transfer in polymers

    International Nuclear Information System (INIS)

    For the present study of free-radical transfer in polymers pulse radiolysis and product studies have been carried out in aqueous solutions using thus far only the water-soluble polymers polyacrylic acid, polymethacrylic acid and polyvinyl alcohol. When OH radicals, generated in the radiolysis of N2O-saturated aqueous solutions, react with polymers the lifetime of the polymer radical thus created very much depends on the number of radicals per polymer chain. When there are a large number of radicals per chain their bimolecular decay may be faster than the corresponding (diffusion controlled) decay of monomeric radicals, but when the macromolecule contains only few or even just one radical their lifetime is considerably prolonged. Highly charged polymers such as polyacrylic acid at high pH attain a rod-like conformation which again favors a long lifetime of the radicals. Under such conditions, radical transfer reactions can occur. For example, in polyacrylic acid OH radicals generate two kinds of radicals side by side. The radical in ?-position to the carboxylate group converts into the thermodynamically more stable ?-radicals by an H-transfer reaction as can be followed by spectrophotometry. Besides radical transfer reactions ?-fragmentation reactions occur causing chain scission. Such reactions can be followed in a pulse radiolysis experiment by conductometry, because counter ions are released upon chain scission. Such a process is especially effective in the case of polymethacrylic acid, where it results in a chain depolymerization. An intramolecular H-abstraction is also observed in the ?-radiolysis of polyacrylic acid with the corresponding peroxyl radicals. This causes a chain reaction to occur. The resulting hydroperoxides are unstable and decarboxylate given rise to acetylacetone-like products. In polyvinyl alcohol the peroxyl radicals in ?-position to the alcohol function undergo HO2-elimination. This prevents a scission of the polymer chain in the bimolecular decay of the peroxyl radicals. (author)

  7. ABT-869, a promising multi-targeted tyrosine kinase inhibitor: from bench to bedside

    Directory of Open Access Journals (Sweden)

    Goh Boon-Cher

    2009-07-01

    Full Text Available Abstract Tyrosine Kinase Inhibitors (TKI have significantly changed the landscape of current cancer therapy. Understanding of mechanisms of aberrant TK signaling and strategies to inhibit TKs in cancer, further promote the development of novel agents. ABT-869, a novel ATP-competitive receptor tyrosine kinase inhibitor is a potent inhibitor of members of the vascular endothelial growth factor (VEGF and platelet derived growth factor (PDGF receptor families. ABT-869 showed potent antiproliferative and apoptotic properties in vitro and in animal cancer xenograft models using tumor cell lines that were "addicted" to signaling of kinases targeted by ABT-869. When given together with chemotherapy or mTOR inhibitors, ABT-869 showed at least additive therapeutic effects. The phase I trial for ABT-869 was recently completed and it demonstrated respectable efficacy in solid tumors including lung and hepatocellular carcinoma with manageable side effects. Tumor cavitation and reduction of contrast enhancement after ABT-869 treatment supported the antiangiogenic activity. The correlative laboratory studies conducted with the trial also highlight potential biomarkers for future patient selection and treatment outcome. Parallel to the clinical development, in vitro studies on ABT-869 resistance phenotype identified novel resistance mechanism that may be applicable to other TKIs. The future therapeutic roles of ABT-869 are currently been tested in phase II trials.

  8. Effect of UV-C irradiation and low temperature storage on bioactive compounds, antioxidant enzymes and radical scavenging activity of papaya fruit.

    Science.gov (United States)

    Rivera-Pastrana, Dulce M; Gardea, Alfonso A; Yahia, Elhadi M; Martínez-Téllez, Miguel A; González-Aguilar, Gustavo A

    2014-12-01

    Mature green 'Maradol' papaya fruits were exposed to ultraviolet (UV)-C irradiation (1.48 kJ·m(-2)) and stored at 5 or 14 °C. Changes in total phenols, total flavonoids, enzymatic activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), as well as the scavenging activity against 2,2-diphenyl-1picrylhydrazyl (DPPH) and 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radicals were investigated in peel and flesh tissues at 0, 5, 10 and 15 days of storage. UV-C irradiation increased significantly (P papaya peel during storage at 5 °C. UV-C irradiation effect on radical scavenging of papaya peel could be attributed to increased flavonoid content. Papaya antioxidant system was activated by UV-C and cold storage by increasing phenolic content and antioxidant enzymatic activities as a defense response against oxidative-stress. PMID:25477649

  9. Free radical derivatives formed from cyclooxygenase-catalyzed dihomo-?-linolenic acid peroxidation can attenuate colon cancer cell growth and enhance 5-fluorouracil?s cytotoxicity

    Directory of Open Access Journals (Sweden)

    Yi Xu

    2014-01-01

    Full Text Available Dihomo-?-linolenic acid (DGLA and its downstream fatty acid arachidonic acid (AA are both nutritionally important ?–6 polyunsaturated fatty acids (?–6s. Evidence shows that, via COX-mediated peroxidation, DGLA and its metabolites (1-series prostaglandins are associated with anti-tumor activity, while AA and its metabolites (2-series prostaglandins could be tightly implicated in various cancer diseases. However, it still remains a mystery why DGLA and AA possess contrasting bioactivities. Our previous studies showed that DGLA could go through an exclusive C-8 oxygenation pathway during COX-catalyzed lipid peroxidation in addition to a C-15 oxygenation pathway shared by both DGLA and AA, and that the exclusive C-8 oxygenation could lead to the production of distinct DGLA?s free radical derivatives that may be correlated with DGLA?s anti-proliferation activity. In the present work, we further investigate the anti-cancer effect of DGLA?s free radical derivatives and their associated molecular mechanisms. Our study shows that the exclusive DGLA?s free radical derivatives from C-8 oxygenation lead to cell growth inhibition, cell cycle arrest and apoptosis in the human colon cancer cell line HCA-7 colony 29, probably by up-regulating the cancer suppressor p53 and the cell cycle inhibitor p27. In addition, these exclusive radical derivatives were also able to enhance the efficacy of 5-Fluorouracil (5-FU, a widely used chemo-drug for colon cancer. For the first time, we show how DGLA?s radical pathway and metabolites are associated with DGLA?s anti-cancer activities and able to sensitize colon cancer cells to chemo-drugs such as 5-FU. Our findings could be used to guide future development of a combined chemotherapy and dietary care strategy for colon cancer treatment.

  10. Dimer esters in ?-pinene secondary organic aerosol: effect of hydroxyl radical, ozone, relative humidity and aerosol acidity

    Science.gov (United States)

    Kristensen, K.; Cui, T.; Zhang, H.; Gold, A.; Glasius, M.; Surratt, J. D.

    2013-12-01

    The formation of secondary organic aerosol (SOA) from both ozonolysis and hydroxyl radical (OH)-initiated oxidation of ?-pinene under conditions of high nitric oxide (NO) concentrations with varying relative humidity (RH) and aerosol acidity was investigated in the University of North Carolina dual outdoor smog chamber facility. SOA formation from ozonolysis of ?-pinene was enhanced relative to that from OH-initiated oxidation in the presence of initially high NO conditions. However, no effect of RH on SOA mass was evident. Ozone (O3)-initiated oxidation of ?-pinene in the presence of ammonium sulfate (AS) seed coated with organic aerosol from OH-initiated oxidation of ?-pinene showed reduced nucleation compared to ozonolysis in the presence of pure AS seed aerosol. The chemical composition of ?-pinene SOA was investigated by ultra-performance liquid chromatography/electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-Q-TOFMS), with a focus on the formation of carboxylic acids and high-molecular weight dimer esters. A total of eight carboxylic acids and four dimer esters were identified, constituting between 8 and 12% of the total ?-pinene SOA mass. OH-initiated oxidation of ?-pinene in the presence of nitrogen oxides (NOx) resulted in the formation of highly oxidized carboxylic acids, such as 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA) and diaterpenylic acid acetate (DTAA). The formation of dimer esters was observed only in SOA produced from the ozonolysis of ?-pinene in the absence of NOx, with increased concentrations by a~factor of two at higher RH (50-90%) relative to lower RH (30-50%). The increased formation of dimer esters correlates with an observed increase in new particle formation at higher RH due to nucleation. Increased aerosol acidity was found to have a negligible effect on the formation of the dimer esters. SOA mass yield did not influence the chemical composition of SOA formed from ?-pinene ozonolysis with respect to carboxylic acids and dimer esters. The results support the formation of the high-molecular weight dimer esters through gas-phase reactions of the stabilized Criegee Intermediate (sCI) formed from the ozonolysis of ?-pinene. The high molecular weight and polar nature of dimer esters formed in the gas-phase may explain increased particle number concentration as a~result of homogenous nucleation. Since three of these dimer esters (i.e., pinyl-diaterpenyl ester (MW 358), pinyl-diaterebyl ester (MW 344) and pinonyl-pinyl ester (MW 368)) have been observed in both laboratory-generated and ambient fine organic aerosol samples, we conclude that the dimer esters observed in this study can be used as tracers for the O3-initiated oxidation of ?-pinene, and are therefore indicative of enhanced anthropogenic activities, and that the high molecular weight and low volatility esters result in homogenous nucleation under laboratory conditions, increasing the particle number concentration.

  11. Melt Free-Radical Grafting of Maleic Anhydride onto Biodegradable Poly(lactic acid by Using Styrene as A Comonomer

    Directory of Open Access Journals (Sweden)

    Piming Ma

    2014-05-01

    Full Text Available Maleic anhydride (MA was grafted onto poly(lactic acid (PLA in the presence of styrene (St by using a free-radical grafting methodology. The grafting degree (Dg of MA was increased from 0.65 wt % to 1.1 wt % with the St/MA ratio up to 2/1, where the grafting efficiency (Eg of MA was 27%. However, both Dg and Eg were decreased with further increasing of the St/MA ratio to 4/1. The Dg of MA increased with MA concentration and showed a maximum at 180 °C in the temperature range of 165 °C–190 °C. The grafting mechanisms of MA in the presence of St are analyzed based on titration, thermogravimetric analysis and infrared results, i.e., MA is grafted onto PLA chains via single monomers and a charge-transfer-complex (CTC at St/MA ratios of ? 1/1, while dominantly via St-co-MA oligomers at St/MA ratios of around 2/1. Copolymerization rather than grafting of St and MA occurs at St/MA ratios of around 4/1. The thermal stability of PLA was compromised to a certain extent by the grafting of MA, resulting in reductions in the decomposition temperature (Td-5% and molecular weight of the PLA. In addition, the crystallization and melting temperatures of the PLA were slightly reduced after the grafting.

  12. Radical Scavenging Capacity and Antioxidant Activity of the Vitamin E Extracted from Palm Fatty Acid Distillate by Sequential Cooling Hexane

    Directory of Open Access Journals (Sweden)

    Ronnakorn Sroynak

    2013-03-01

    Full Text Available The radical scavenging capacity and antioxidant activity of the vitamin E extracted from palm fatty acid distillate by the sequential cooling hexane were compared to those of the synthetic antioxidants including butylated hydroxyanisole (BHA, 2,6-di-tert-butyl-4-methylphenol (BHT, pyrogallol (PG, tert-butylhydroquinone (TBHQ and commercial Alpha-tocopherol. The extracted vitamin E contained 2,509.57, 9.24, 157.85, 6.70, 1,779.92, 3.97, 2,376.38, 818.80 and 7,662.45 ppm of Alpha-, Beta-, Gamma-, Delta-tocopherol and Alpha-, Beta-, Gamma-, Delta-tocotrienol, and total vitamin E, respectively. The maximum 2,2-diphenyl-1-picrylhydrazyl (DPPH scavenging capacity of 20 ppm extracted vitamin E was 89%. The antioxidant activity determined by the methods of reducing power and ferric thiocyanate indicated that the 2.5 ppm extracted vitamin E could inhibit the oxidation of linoleic acid emulsion for more than 80% within 1 day. The superoxide scavenging activity of the extracted vitamin E was greater than those of the BHT, commercial Alpha-tocopherol, and PG, respectively. The antioxidant activity of the extracted vitamin E was 91% which was similar to those of the BHT and synthetic Alpha-tocopherol. The total-vitamin E remained 73% after heating at 190°C for 3 h. The tocopherol derivatives were more heat-stable than the tocotrienol derivatives while Gamma-tocopherol was the most heat-stable derivative. The concentration of total-vitamin E stored at 30°C for 120 days remained about 87% while the concentrations of vitamin E derivatives reduced by 2-20%.

  13. Chemistry of free radical-induced damage of deoxyribonucleic acid model compounds

    International Nuclear Information System (INIS)

    The main objective of this investigation was to identify the principal lesions produced by ionizing radiation and autoxidation processes in DNA model compounds. Synthetic deoxynuclei acid oligomers were subjected to ionizing radiation in aqueous solutions. The damage products of d(ApT) irradiated under N2O saturation were isolated by reverse phase high performance liquid chromatography in different solvent systems. The major components of the HPLC profile were studied mainly by proton Nuclear Magnetic Resonance spectroscopy. The product profile was dramatically altered when mediators such as oxygen were present. One product, identified as a N-formamido derivative of d(ApT), formed due to the breakdown of the thymine base, was predominant. The presence of radiation protectors markedly altered the products obtained from d(ApT). Two stereoisomers of dihydrothymine derivatives were identified. d(ApT) irradiated in the solid state generated direct damage products which were isolated by HPLC and identified by NMR spectroscopy. A comparative study of the degradation of d(ApT) produced by ionizing radiation and by chemical degradation by autoxidizing agents was carried out. The result showed that the autoxidizing agents produced the same profile of damaged products as ionizing radiation with oxygen present

  14. Activities of ABT-773 against Listeria monocytogenes and Coryneform Bacteria of Clinical Interest

    OpenAIRE

    Conejo, Mari?a Del Carmen; Marti?nez-marti?nez, Luis; Pascual, A?lvaro; Sua?rez, Ana Isabel; Perea, Evelio J.

    2003-01-01

    The in vitro activities of ABT-773 were evaluated against 15 Listeria monocytogenes strains and 196 coryneform bacteria isolated from clinical samples. One hundred percent of the L. monocytogenes strains were inhibited by ?0.015 ?g of ABT-773/ml. MICs of ABT-773 (?g/ml) at which 50% of the isolates tested were inhibited (MIC50s) and MIC90s for other organisms were 0.125 and 0.5 (Corynebacterium amycolatum), 1 and >32 (Corynebacterium jeikeium), 0.03 and >32 (Corynebacterium minutissimum),...

  15. The Effect of Nitrate as a Radical Scavenger for the Removal of Humic Acid from Aqueous Solutions by Electron Beam Irradiation

    Directory of Open Access Journals (Sweden)

    Mohammad Taghi Ghaneian

    2013-01-01

    Full Text Available Introduction: Humic acids have adverse effects on the water quality, then should be removed from water resources. The aim of this study was to evaluate the effect of nitrate as a radical scavenger for removal of humic acid from aqueous solutions by electron beam irradiation. Materials and Methods: In this study, after preparation of stock humic acid solution in alkaline condition, different concentrations of humic acid (10, 25 and 50 mg/l were prepared. Different concentrations of nitrate (25, 50 and 100 mg/l added to humic acid samples and then absorption of samples was measured at 254 nm by using UV-Vis spectrophotometer before and after the electron beam irradiation. This study has done at pH= 8 and at different electron beam adsorbed dose of 1, 3, 6, 9 and 15 kGy. Results: The results of this study showed that the increasing of adsorbed dose from 1 to 15 kGy, the removal efficiency of humic acid also increased. By increasing of nitrate concentration from 25 to 100 mg/l, the removal efficiency of humic acid has decreased from 43.8% to 36.6% and nitrate acts as a radical scavenger. By increasing of humic acid concentration from 10 to 50mg/l, removal efficiency decreased in all adsorbed doses. Kinetic analysis of our results showed that the results well fitted with the second - order reaction. Conclusion: We can conclude from this study that electron beam irradiation could be a useful process for the treatment of natural organic matter (humic acid from surface waters.

  16. Radical scavenging and antioxidant activities of methanolic extracts from Hypericum species growing in Bulgaria

    Directory of Open Access Journals (Sweden)

    Zheleva-Dimitrova Dimitrina

    2010-04-01

    Full Text Available Thirteen Hypericum species growing in Bulgaria were investigated for free radical-scavenging activity, antioxidant activity, total tannins and total flavonoids contents. Methanolic extracts from the Hypericum species were analyzed for radical scavenging and antioxidant activities using DPPH-, ABTS- free radicals, total antioxidant activity and inhibition of lipid peroxidation by ferric thiocyanate (FTC method. Butylated hydroxytoluene and ascorbic acid were used as positive controls. Methanolic extracts from H. cerastoides, H. perforatum and H. maculatum demonstrate the highest antioxidant activities and are potential sources of natural antioxidant compounds. The quantification of tannins and flavanoids were determined in Hypericum species using Folin-Chiocalteu reagent and AlCl3, respectively. The amounts of the tannins ranged from 1.30 ± 0.01 mg/100 g dw in H. elegans to 8.67 ± 0.02 g/100 g dw in H. perforatum. The highest concentration of flavonoids was found in H. cerastoides (1.22 ± 0.02 g/100g dw, and the lowest amount was established in H. olympicum (0.20 ± 0.03 g/100g dw.

  17. Modeling nitrous acid and its impact on ozone and hydroxyl radical during the Texas Air Quality Study 2006

    Directory of Open Access Journals (Sweden)

    B. H. Czader

    2012-08-01

    Full Text Available Nitrous acid (HONO mixing ratios for the Houston metropolitan area were simulated with the Community Multiscale Air Quality (CMAQ Model for an episode during the Texas Air Quality Study (TexAQS II in August/September 2006 and compared to in-situ MC/IC (mist-chamber/ion chromatograph and long path DOAS (Differential Optical Absorption Spectroscopy measurements at three different altitude ranges. Several HONO sources were accounted for in simulations, such as gas phase formation, direct emissions, nitrogen dioxide (NO2 hydrolysis, photo-induced formation from excited NO2 and photo-induced conversion of NO2 into HONO on surfaces covered with organic materials. Compared to the gas-phase HONO formation there was about a tenfold increase in HONO mixing ratios when additional HONO sources were taken into account, which improved the correlation between modeled and measured values. Concentrations of HONO simulated with only gas phase chemistry did not change with altitude, while measured HONO concentrations decrease with height. A trend of decreasing HONO concentration with altitude was well captured with CMAQ predicted concentrations when heterogeneous chemistry and photolytic sources of HONO were taken into account. Heterogeneous HONO production mainly accelerated morning ozone formation, albeit slightly. Also HONO formation from excited NO2 only slightly affected HONO and ozone (O3 concentrations. Photo-induced conversion of NO2 into HONO on surfaces covered with organic materials turned out to be a strong source of daytime HONO. Since HONO immediately photo-dissociates during daytime its ambient mixing ratios were only marginally altered (up to 0.5 ppbv, but significant increase in the hydroxyl radical (OH and ozone concentration was obtained. In contrast to heterogeneous HONO formation that mainly accelerated morning ozone formation, inclusion of photo-induced surface chemistry influenced ozone throughout the day.

  18. Atmospheric chemistry of hydrazoic acid (HN3): UV absorption spectrum, HO reaction rate, and reactions of the N3 radical.

    Science.gov (United States)

    Orlando, John J; Tyndall, Geoffrey S; Betterton, Eric A; Lowry, Joe; Stegall, Steve T

    2005-03-15

    Processes related to the tropospheric lifetime and fate of hydrazoic acid, HN3, have been studied. The ultraviolet absorption spectrum of HN3 is shown to possess a maximum near 262 nm with a tail extending to at least 360 nm. The photolysis quantum yield for HN3 is shown to be approximately 1 at 351 nm. Using the measured spectrum and assuming unity quantum yield throughout the actinic region, a diurnally averaged photolysis lifetime near the earth's surface of 2-3 days is estimated. Using a relative rate method, the rate coefficient for reaction of HO with HN3 was found to be (3.9 +/-0.8) x 10(-12) cm3 molecule(-1) s(-1), substantially larger than the only previous measurement. The atmospheric HN3 lifetime with respect to HO oxidation is thus about 2-3 days, assuming a diurnally averaged [HO] of 10(6) molecule cm(-3). Reactions of N3, the product of the reaction of HO with HN3, were studied in an environmental chamber using an FTIR spectrometer for end-product analysis. The N3 radical reacts efficiently with NO, producing N2O with 100% yield. Reaction of N3 with NO2 appears to generate both NO and N2O, although the rate coefficient for this reaction is slower than that for reaction with NO. No evidence for reaction of N3 with CO was observed, in contrast to previous literature data. Reaction of N3 with O2 was found to be extremely slow, k HN3 was measured using a relative rate method, k = (1.0+/-0.2) x 10(-12) cm3 molecule(-1) s(-1). PMID:15819219

  19. Modeling nitrous acid and its impact on ozone and hydroxyl radical during the Texas Air Quality Study 2006

    Directory of Open Access Journals (Sweden)

    B. H. Czader

    2012-02-01

    Full Text Available Nitrous acid (HONO mixing ratios for the Houston metropolitan area were simulated with the Community Multiscale Air Quality (CMAQ model for an episode during the Texas Air Quality Study (TexAQS II in August/September 2006 and compared to in-situ MC/IC (mist-chamber/ion chromatograph and long path DOAS (Differential Optical Absorption Spectroscopy measurements at three different altitudes. Several HONO sources were accounted for in simulations, such as gas phase formation, direct emissions, nitrogen dioxide (NO2* hydrolysis, photo-induced formation from excited NO2* and photo-induced conversion of NO2 into HONO on surfaces covered with organic materials. Compared to the gas-phase HONO formation there was about a tenfold increase in HONO mixing ratios when additional HONO sources were taken into account, which improved the correlation between modeled and measured values. Concentrations of HONO simulated with only gas phase chemistry did not change with altitude, while measured HONO concentrations decrease with height. A trend of decreasing HONO concentration with altitude was well captured with CMAQ predicted concentrations when heterogeneous chemistry and photolytic sources of HONO were taken into account. Heterogeneous HONO production mainly accelerated morning ozone formation, albeit slightly. Also HONO formation from excited NO2 only slightly affected HONO and ozone (O3 concentrations. Photo-induced conversion of NO2 into HONO on surfaces covered with organic materials turned out to be a strong source of daytime HONO. Since HONO immediately photo-dissociates during daytime its ambient mixing ratios were only marginally altered (up to 0.5 ppbv, but significant increase in the hydroxyl radical (OH and ozone concentration was obtained. In contrast to heterogeneous HONO formation that mainly accelerated morning ozone formation, inclusion of photo-induced surface chemistry influenced ozone throughout the day.

  20. Protective effect of aqueous extract from Spirulina platensis against cell death induced by free radicals

    Directory of Open Access Journals (Sweden)

    Radhakrishnan Ammu

    2010-09-01

    Full Text Available Abstract Background Spirulina is a commercial alga well known to contain various antioxidants, especially phycocyanin. Apart from being sold as a nutraceutical, Spirulina is incorporated as a functional ingredient in food products and beverages. Most of the previous reports on antioxidant activity of Spirulina were based on chemical rather than cell-based assays. The primary objective of this study was to assess the antioxidant activity of aqueous extract from Spirulina based on its protective effect against cell death induced by free radicals. Methods The antioxidant activity of the cold water extract from food-grade Spirulina platensis was assessed using both chemical and cell-based assays. In the cell-based assay, mouse fibroblast cells (3T3 cells were incubated for 1 h in medium containing aqueous extract of Spirulina or vitamin C (positive control at 25, 125 and 250 ?g/mL before the addition of 50 ?M 1,1-diphenyl-2-picrylhydrazyl (DPPH or 3-ethylbenzothiazoline-6-sulfonic acid (ABTS. The cells were incubated for another 24 h before being assessed for cell death due to apoptosis using the Cell Death Detection ELISA Kit. Spectrophotometric assays based on DPPH and ABTS were also used to assess the antioxidant activity of the extract compared to vitamin C and vitamin E (positive controls. Results Spirulina extract did not cause cytotoxic effect on 3T3 cells within the range of concentrations tested (0 - 250 ?g/mL. The extract reduced significantly (p Conclusions The results showed that aqueous extract of Spirulina has a protective effect against apoptotic cell death due to free radicals. The potential application of incorporating Spirulina into food products and beverages to enhance their antioxidant capacity is worth exploring.

  1. Chemical composition, fatty acid content and antioxidant potential of meat from goats supplemented with Moringa (Moringa oleifera) leaves, sunflower cake and grass hay.

    Science.gov (United States)

    Qwele, K; Hugo, A; Oyedemi, S O; Moyo, B; Masika, P J; Muchenje, V

    2013-03-01

    The present study determined the chemical composition, fatty acid (FA) content and antioxidant capacity of meat from goats supplemented with Moringa oleifera leaves (MOL) or sunflower cake (SC) or grass hay (GH). The meat from goat supplemented with MOL had higher concentrations of total phenolic content (10.62±0.27 mg tannic acid equivalent E/g). The MOL significantly scavenged 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic-acid (ABTS) radical to 93.51±0.19% (93.51±0.19%) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical to 58.95±0.3% than other supplements. The antioxidative effect of MOL supplemented meat on catalase (CAT), reduced glutathione (GSH), superoxide dismutase (SOD) and lipid oxidation (LO) was significantly (Psupplemented with sunflower seed cake. The present study indicated that the anti-oxidative potential of MOL may play a role in improving meat quality (chemical composition, colour and lipid stability). PMID:23273450

  2. Free Radical Scavenging Profile and Myeloperoxidase Inhibition of Extracts from Antidiabetic Plants: Bauhinia forficata and Cissus sicyoides

    Scientific Electronic Library Online (English)

    NAJEH M, KHALIL; MARIA T, PEPATO; IGUATEMY L, BRUNETTI.

    Full Text Available There is abundant evidence that reactive oxygen species are implicated in several physiological and pathological processes. To protect biological targets from oxidative damage, antioxidants must react with radicáis and other reactive species faster than biological substrates do. The aim of the prese [...] nt study was to determine the in vitro antioxidant activity of aqueous extracts from leaves of Bauhinia forficata Link (Fabaceae - Caesalpinioideae) and Cissus sicyoides L. (Vitaceae) (two medicinal plants used popularly in the control of diabetes mellitus), using several different assay systems, namely, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) decolorization, superoxide anión radical (0(2)•-) scavenging and myeloperoxidase (MPO) activity. In the ABTS assay for total antioxidant activity, B. forficata showed IC50 = 8.00±0.07 ?g/mL, while C. sicyoides showed IC50 = 13.0±0.2 ?g/mL. However, the extract of C. sicyoides had a stronger effect on 0(2)•- (IC50 = 60.0±2.3 ?g/mL) than the extract of B. forficata (IC50 = 90.0±4.4 ?g/ mL). B. forficata also had a stronger inhibitory effect on MPO activity, as measured by guaiacol oxidation, than C. sicyoides. These results indicate that aqueous extracts of leaves of B. forficata and C. sicyoides are a potential source of natural antioxidants and may be helpful in the prevention of diabetic complications associated with oxidative stress.

  3. Growth of ABT-5 bacteria culture in whey supplemented with whey protein concentrate

    OpenAIRE

    Bojan Matijevi?; Rajka Božani?; Ljubica Tratnik

    2010-01-01

    The objective of this research was to decrease the duration of whey fermentation and to analyze the impact of whey protein concentrates (WPC) addition on growth and activity as well as on survival of mixed ABT-5 culture bacteria (Lactobacillus acidophilus, Bifidobacterium spp. and Streptococcus thermophilus) during 28 days of fermented whey cold storage (5 °C). Whey fermentation was observed at 37 °C with and without 1.5 and 3 % WPC addition. Whey fermentation with mixed ABT-5 bacterial cul...

  4. Different catalytic effects of a single water molecule: the gas-phase reaction of formic acid with hydroxyl radical in water vapor.

    Science.gov (United States)

    Anglada, Josep M; Gonzalez, Javier

    2009-12-01

    The effect of a single water molecule on the reaction mechanism of the gas-phase reaction between formic acid and the hydroxyl radical was investigated with high-level quantum mechanical calculations using DFT-B3LYP, MP2 and CCSD(T) theoretical approaches in concert with the 6-311+G(2df,2p) and aug-cc-pVTZ basis sets. The reaction between HCOOH and HO has a very complex mechanism involving a proton-coupled electron transfer process (pcet), two hydrogen-atom transfer reactions (hat) and a double proton transfer process (dpt). The hydroxyl radical predominantly abstracts the acidic hydrogen of formic acid through a pcet mechanism. A single water molecule affects each one of these reaction mechanisms in different ways, depending on the way the water interacts. Very interesting is also the fact that our calculations predict that the participation of a single water molecule results in the abstraction of the formyl hydrogen of formic acid through a hydrogen atom transfer process (hat). PMID:19830768

  5. Damage of aromatic amino acids by the atmospheric free radical oxidant NO3? in the presence of NO2?, N2O4, O3 and O2.

    Science.gov (United States)

    Goeschen, Catrin; Wibowo, Natalia; White, Jonathan M; Wille, Uta

    2011-05-01

    Analysis of the products formed in the reaction of NO(3)? with the N- and C-protected aromatic amino acids 1-5, which was performed under conditions that simulate exposure of biosurfaces to environmental pollutants, revealed insight how this important atmospheric free-radical oxidant can cause irreversible damage. In general, NO(3)? induced electron transfer at the aromatic ring is the exclusive initial pathway in a multi-step sequence, which ultimately leads to nitroaromatic compounds. In the reaction of NO(3)? with tryptophan 5 tricyclic products 12 and 13 are formed through an intramolecular, oxidative cyclization involving the amide moiety. In addition to this, strong indication for formation of N-nitrosamides was obtained, which likely result from reaction with N(2)O(4) through an independent non-radical pathway. PMID:21412525

  6. Biomimetic reagents for the selective free radical and acid-base chemistry of glycans: application to glycan structure determination by mass spectrometry.

    Science.gov (United States)

    Gao, Jinshan; Thomas, Daniel A; Sohn, Chang Ho; Beauchamp, J L

    2013-07-24

    Nature excels at breaking down glycans into their components, typically via enzymatic acid-base catalysis to achieve selective cleavage of the glycosidic bond. Noting the importance of proton transfer in the active site of many of these enzymes, we describe a sequestered proton reagent for acid-catalyzed glycan sequencing (PRAGS) that derivatizes the reducing terminus of glycans with a pyridine moiety possessing moderate proton affinity. Gas-phase collisional activation of PRAGS-derivatized glycans predominately generates C1-O glycosidic bond cleavages retaining the charge on the reducing terminus. The resulting systematic PRAGS-directed deconstruction of the glycan can be analyzed to extract glycan composition and sequence. Glycans are also highly susceptible to dissociation by free radicals, mainly reactive oxygen species, which inspired our development of a free radical activated glycan sequencing (FRAGS) reagent, which combines a free radical precursor with a pyridine moiety that can be coupled to the reducing terminus of target glycans. Collisional activation of FRAGS-derivatized glycans generates a free radical that reacts to yield abundant cross-ring cleavages, glycosidic bond cleavages, and combinations of these types of cleavages with retention of charge at the reducing terminus. Branched sites are identified with the FRAGS reagent by the specific fragmentation patterns that are observed only at these locations. Mechanisms of dissociation as well as application of the reagents for both linear and highly branched glycan structure analysis are investigated and discussed. The approach developed here for glycan structure analysis offers unique advantages compared to earlier studies employing mass spectrometry for this purpose. PMID:23806039

  7. Oil, protein, antioxidants and free radical scavenging activity of stone from wild olive trees (Olea europaea L.).

    Science.gov (United States)

    Hannachi, Hédia; Elfalleh, Walid; Marzouk, Sizaiem

    2013-05-01

    The wild olive trees or oleaster (var. sylvestris) and the cultivated olive trees (var. europaea) constitute the two botanical varieties of Olea europaea L. from Mediterranean. In this study, a partial chemical profile was conducted including the total lipids, the fatty acid profiles, soluble proteins, polyphenols, flavanoids contents and antioxidants activities of stone from six oleaster trees. The comparison was made by two olive cultivars cultivated in the same region. The oleaster and cultivar stones were richer in oil content having an average of 8.99 and 7.38 % dry weight basis (DW), respectively. Qualitatively, all studied oils have the same fatty acids profile with the oleic acid C18:1n-9 as the major fatty acid. The oleaster stone oils were richer in monounsaturated fatty acids having an average of 64.87%. They, also, richer in protein content with an average of 198.86 mg/g DW.The globulin is the major fraction, followed by the albumin, the prolamin and the glutemin fractions. The oleaster stone extracts contain polyphenols, flavonoids with an average of 151.14 and 11.91 mg gallic acid equivalent/100g of DW, respectively. The studied extracts showed antioxidant activity using the free radical scavenging activity determined by DPPH and ABTS. The unexploited oleaster stone seems to be a source of oil with good fatty acids balance, in protein and antioxidants metabolites and would be useful for the formulation of supplements and/or pharmaceutical ingredients. PMID:23625423

  8. Reactivity of beer bitter acids toward the 1-hydroxyethyl radical as probed by spin-trapping electron paramagnetic resonance (EPR) and electrospray ionization-tandem mass spectrometry (ESI-MS/MS).

    Science.gov (United States)

    de Almeida, Natália E C; Homem-de-Mello, Paula; De Keukeleire, Denis; Cardoso, Daniel R

    2011-04-27

    The iso-?-acids or isohumulones are the major contributors to the bitter taste of beer, and it is well-recognized that they are degraded during beer aging. In particular, the trans-isohumulones seem to be less stable than the cis-isohumulones. The major radical identified in beer is the 1-hydroxyethyl radical; however, the reactivity between this radical and the isohumulones has not been reported until now. Therefore, we studied the reactivity of isohumulones toward the 1-hydroxyethyl radical through a competitive kinetic approach. It was observed that both cis- and trans-isohumulones and dihydroisohumulones are decomposed in the presence of 1-hydroxyethyl radicals, while the reactivities are comparable. On the other hand, the tetrahydroisohumulones did not react with 1-hydroxyethyl radicals. The apparent second-order rate constants for the reactions between the 1-hydroxyethyl radical and these compounds were determined by electron paramagnetic resonance (EPR) spectroscopy and electrospray ionization-tandem mass spectrometry [ESI(+)-MS/MS]. It follows that degradation of beer bitter acids is highly influenced by the presence of 1-hydroxyethyl radicals. The reaction products were detected by liquid chromatography-electrospray ionization-ion trap-tandem mass spectrometry (LC-ESI-IT-MS/MS), and the formation of oxidized derivatives of the isohumulones was confirmed. These data help to understand the mechanism of beer degradation upon aging. PMID:21401101

  9. Dihydroasparagusic acid: antioxidant and tyrosinase inhibitory activities and improved synthesis.

    Science.gov (United States)

    Venditti, Alessandro; Mandrone, Manuela; Serrilli, Anna Maria; Bianco, Armandodoriano; Iannello, Carmelina; Poli, Ferruccio; Antognoni, Fabiana

    2013-07-17

    Dihydroasparagusic acid (DHAA) is the reduced form of asparagusic acid, a sulfur-containing flavor component produced by Asparagus plants. In this work, DHAA was synthetically produced by modifying some published protocols, and the synthesized molecule was tested in several in vitro assays (DPPH, ABTS, FRAP-ferrozine, BCB, deoxyribose assays) to evaluate its radical scavenging activity. Results show that DHAA is endowed with a significant in vitro antioxidant activity, comparable to that of Trolox. DHAA was also evaluated for its inhibitory activity toward tyrosinase, an enzyme involved, among others, in melanogenesis and in browning processes of plant-derived foods. DHAA was shown to exert an inhibitory effect on tyrosinase activity, and the inhibitor kinetics, analyzed by a Lineweaver-Burk plot, exhibited a competitive mechanism. Taken together, these results suggest that DHAA may be considered as a potentially active molecule for use in various fields of application, such as pharmaceutical, cosmetics, agronomic and food. PMID:23790134

  10. A new polyphenol, 1, 3-di-O-caffeoyl-5-O-(1-methoxyl-2-O-caffeoyl-4-maloyl)-quinic acid, isolated from cultured cells of Saussurea involucrata.

    Science.gov (United States)

    Zou, Xiao-Wei; Liu, Dan; Liu, Ya-Ping; Xiu, Zhi-Long; Xiao, Hong-Bin

    2015-04-01

    The present study was designed to isolate the polyphenol constituents of cultured cells of Saussurea involucrata. The polyphenol type constituents were isolated using chromatography methods, and then characterized by spectral analysis. 1,1-Diphenyl-2-picrylhydrazyl radical 2,2-Diphenyl-1-(2,4,6-trinitrophenyl)-hydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) free radical scavenging were assayed using Vitamin C as the positive control. One new polyphenol 18, 1, 3-di-O-caffeoyl-5-O-(1-methoxyl-2-O-caffeoyl-4-maloyl)-quinic acid, together with 17 known compounds, was isolated and characterized. In conclusion, Compound 18 was a new caffeoyl maloyl quinic acid type polyphenol and showed desired vitro anti-oxidant activity. Compounds 1-5, 9, 10, 14, 15, and 17 were isolated from cultured cells of Saussurea involucrata for the first time. PMID:25908627

  11. In Vitro Antioxidant Activities, Free Radical Scavenging Capacity, and Tyrosinase Inhibitory of Flavonoid Compounds and Ferulic Acid from Spiranthes sinensis (Pers. Ames

    Directory of Open Access Journals (Sweden)

    Chung Pin Liang

    2014-04-01

    Full Text Available In this study, ultrasound-assisted extraction (UAE and other methods of extracting flavonoid compounds and ferulic acid (FA from S. sinensis were investigated. Five different extraction methods, including water extraction (W, water extraction using UAE (W+U, 75% ethanol extraction (E, 75% ethanol extraction using UAE (E+U, and supercritical CO2 extraction (SFE were applied in the extraction of bioactive compounds (flavonoids and ferulic acid in order to compare their efficiency. The highest yield of flavonoids (4.28 mg/g and ferulic acid (4.13 mg/g content was detected in the E+U extract. Furthermore, S. sinensis extracts obtained by E+U show high antioxidant activity, and IC50 values of 0.47 mg/mL for DPPH radicals and 0.205 mg/mL for metal chelating activity. The total antioxidant assay shows superoxide radical scavenging capacity and in vitro mushroom tyrosinase inhibition in a dose-dependent manner, suggesting that E+U can be used for extraction of bioactive compounds from S. sinensis.

  12. Physiology of free radicals

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    Stevanovi? Jelka

    2011-01-01

    Full Text Available Free radicals imply that every atom, molecule, ion, group of atoms, or molecules with one or several non-paired electrons in outer orbital. Among these are: nitrogenoxide (NO•, superoxide-anion-radical (O2•-, hydroxyl radical (OH•, peroxyl radical (ROO•, alcoxyl radical (RO• and hydroperoxyl radical (HO2•. However, reactive oxygen species also include components without non-paired electrons in outer orbital (so-called reactive non-radical agents, such as: singlet oxygen (1O2, peroxynitrite (ONOO-, hydrogen-peroxide (H2O2, hypochloric acid (eg. HOCl and ozone (O3. High concentrations of free radicals lead to the development of oxidative stress which is a precondition for numerous pathological effects. However, low and moderate concentrations of these matter, which occur quite normally during cell metabolic activity, play multiple significant roles in many reactions. Some of these are: regulation of signal pathways within the cell and between cells, the role of chemoattractors and leukocyte activators, the role in phagocytosis, participation in maintaining, changes in the position and shape of the cell, assisting the cell during adaption and recovery from damage (e.g.caused by physical effort, the role in normal cell growth, programmed cell death (apoptosis and cell ageing, in the synthesis of essential biological compounds and energy production, as well as the contribution to the regulation of the vascular tone, actually, tissue vascularization.

  13. Antioxidant and Free Radical Scavenging Capacity of Crude and Refined Oil Extracted From Azadirachta indica A. Juss.

    Directory of Open Access Journals (Sweden)

    Sunday O. Okoh

    2015-01-01

    Full Text Available Naturally nutritive and non-nutritive occurring antioxidants have been proven potent and safe for management of variety of diseases. This study investigated the antioxidant and free radical scavenging capacity of crude and refined Azadirachta indica (Neem tree oil. The neem crude oil (NCO was extracted from the seeds by mechanical press and degummed. The neem oil was de-pigmented with activated charcoal, and fractionated with silica gel in a capillary column. The ability of the oils to act as hydrogen/electrons donor were determined in-vitro using 2, 2-dipphenyl-1-picrylhydrazyl (DPPH, 2, 2-azinobis - (3-ethylbenzothiazolin - 6-sulfonic acid diammonium salt (ABTS, lipid peroxyl (LP and nitric oxide (NO radicals scavenging assays, at different extract concentrations (0.1, 0.2, 0.3 and 0.4 mg/mL. The IC50 of the NCO oil (1.50 ± 0.10 mg/mL showed that antioxidant activity is comparable to vitamin C and beta-carotene (1.60 ± 0.10 and 1.27 ± 0.12 mg/mL respectively in scavenging DPPH radical. The crude neem oil exhibited superior activity against NO radical, than the refined oil and vitamin C. Generally, in the four antioxidant assays, a significant correlation existed between concentrations of the oils and percentage inhibition of the four different radicals. GC/MS analyses identified monounsaturated and saturated fatty acids, aldehydes and pentanethiol as the major compounds in the oils, these may account for their antioxidant capacity.

  14. Inhibition of radical reactions for an improved potassium tert-butoxide-promoted (11) C-methylation strategy for the synthesis of ?-(11) C-methyl amino acids.

    Science.gov (United States)

    Suzuki, Chie; Kato, Koichi; Tsuji, Atsushi B; Zhang, Ming-Rong; Arano, Yasushi; Saga, Tsuneo

    2015-03-01

    ?-(11) C-Methyl amino acids are useful tools for biological imaging studies. However, a robust procedure for the labeling of amino acids has not yet been established. In this study, the (11) C-methylation of Schiff-base-activated ?-amino acid derivatives has been optimized for the radiosynthesis of various ?-(11) C-methyl amino acids. The benzophenone imine analog of methyl 2-amino butyrate was (11) C-methylated with [(11) C]methyl iodide following its initial deprotonation with potassium tert-butoxide (KOtBu). The use of an alternative base such as tetrabutylammonium fluoride, triethylamine, and 1,8-diazabicyclo[5.4.0]undec-7-ene did not result in the (11) C-methylated product. Furthermore, the KOtBu-promoted (11) C-methylation of the Schiff-base-activated amino acid analog was enhanced by the addition of 1,2,4,5-tetramethoxybenzene or 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and inhibited by the addition of 1,10-phenanthroline. These results suggest that inhibition of radical generation induced by KOtBu improves the ?-(11) C-methylation of the Schiff-base-activated amino acids. The addition of a mixture of KOtBu and TEMPO to a solution of Schiff-base-activated amino acid ester and [(11) C]methyl iodide provided optimal results, and the tert-butyl ester and benzophenone imine groups could be readily hydrolyzed to give the desired ?-(11) C-methyl amino acids with a high radiochemical conversion. This strategy could be readily applied to the synthesis of other ?-(11) C-methyl amino acids. PMID:25690316

  15. Studies on the syntheses, structural characterization, antimicrobial-, and DPPH radical scavenging activity of the cocrystals caffeine:cinnamic acid and caffeine:eosin dihydrate

    Science.gov (United States)

    Suresh Kumar, G. S.; Seethalakshmi, P. G.; Bhuvanesh, N.; Kumaresan, S.

    2013-10-01

    Two organic cocrystals namely, caffeine:cinnamic acid [(caf)(ca)] (1) and caffeine:eosin dihydrate [(caf)(eos)]·2H2O (2) were synthesized and studied by FT-IR, TGA/DTA, and single crystal XRD. The crystal system of cocrystal 1 is triclinic with space group P-1 and Z = 2 and that of cocrystal 2 is monoclinic with space group P21/C and Z = 4. An imidazole-carboxylic acid synthon is observed in the cocrystal 1. The intermolecular hydrogen bond, O-H⋯N and ?-? interactions play a major role in stabilizing 1 whereas the intermolecular hydrogen bonds, O-H⋯O, O-H⋯N, and intramolecular hydrogen bond, O-H⋯Br; along with ?-? interactions together play a vital role in stabilizing the structure of 2. The antimicrobial- and DPPH radical scavenging activities of both the cocrystals were studied.

  16. Effect of free radical spin trap N-tert-butyl-alpha-phenylnitrone (PBN) on seizures induced in immature rats by homocysteic acid.

    Science.gov (United States)

    Folbergrová, Jaroslava; Druga, Rastislav; Otáhal, Jakub; Haugvicová, Renata; Mares, Pavel; Kubová, Hana

    2006-09-01

    The present study has examined the effect of free radical spin trap N-tert-butyl-alpha-phenylnitrone (PBN) in the model of seizures induced in immature 12-day-old rats by bilateral intracerebroventricular infusion of dl-homocysteic acid (dl-HCA, 600 nmol/side). PBN was given i.p. in two doses (100 mg/kg each), 30 min prior and 30 min after dl-HCA infusion. PBN did not significantly influence the severity of seizures, evident both from the behavioral symptoms and EEG recordings. PBN normalized decreased ATP levels in the hippocampus, occurring during the acute phase of seizures ( approximately 45-50 min after infusion) and persisting until the end of the 24-h recovery period. PBN also led to normalization of decreased glucose levels and to a significant reduction of lactate accumulation in the cerebral cortex and hippocampus. The neuroprotective effect of PBN was evaluated after 24 h and 6 days of survival following dl-HCA-induced seizures (Nissl and Fluoro-Jade B staining). The administration of PBN resulted in a partial amelioration of severe damage observed in many brain regions following infusion of dl-HCA alone. The data suggest that increased free radical production is apparently occurring during seizures induced in immature rats by homocysteic acid. Free radical scavenger PBN had a clear-cut protective effect, evident as the improved recovery of brain energy status and as a partial, but significant, attenuation of neuronal degeneration associated with this model of seizures. PMID:16756975

  17. Enzyme inhibitory and radical scavenging effects of some antidiabetic plants of Turkey

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    Nilüfer Orhan

    2014-06-01

    Full Text Available Objective(s:Ethnopharmacological field surveys demonstrated that many plants, such as Gentiana olivieri, Helichrysum graveolens, Helichrysum plicatum ssp. plicatum, Juniperus oxycedrus ssp. oxycedrus, Juniperus  communis var. saxatilis, Viscum album (ssp. album, ssp. austriacum, are used as traditional medicine for diabetes in different regions of Anatolia. The present study was designed to evaluate the in vitro antidiabetic effects of some selected plants, tested in animal models recently. Materials and Methods: ?-glucosidase and ?-amylase enzyme inhibitory effects of the plant extracts were investigated and Acarbose was used as a reference drug. Additionally, radical scavenging capacities were determined using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid ABTS radical cation scavenging assay and total phenolic content of the extracts were evaluated using Folin Ciocalteu method. Results: H. graveolens ethanol extract exhibited the highest inhibitory activity (55.7 % ± 2.2 on ?-amylase enzyme. Additionally, J. oxycedrus hydro-alcoholic leaf extract had potent ?-amylase inhibitory effect, while the hydro-alcoholic extract of J. communis fruit showed the highest ?-glucosidase inhibitory activity (IC50: 4.4 ?g/ml. Conclusion:Results indicated that, antidiabetic effect of hydro-alcoholic extracts of H. graveolens capitulums, J. communis fruit and J. oxycedrus leaf might arise from inhibition of digestive enzymes.

  18. In Vitro and In Vivo Enhancement of Chemoradiation Using the Oral PARP Inhibitor ABT-888 in Colorectal Cancer Cells

    International Nuclear Information System (INIS)

    Purpose: Poly(ADP-ribose) polymerase plays a critical role in the recognition and repair of DNA single-strand breaks and double-strand breaks (DSBs). ABT-888 is an orally available inhibitor of this enzyme. This study seeks to evaluate the use of ABT-888 combined with chemotherapy and radiation therapy (RT) in colorectal carcinoma models. Methods and Materials: RT clonogenic assays were performed on HCT116 and HT29 cells treated with 5-fluorouracil, irinotecan, or oxaliplatin with or without ABT. The surviving fraction at 2 Gy and dose-modifying factor at 10% survival were analyzed. Synergism was assessed by isobologram analysis for combination therapies. ?H2AX and neutral comet assays were performed to assess the effect of therapy on DSB formation/repair. In vivo assessments were made by use of HCT116 cells in a xenograft mouse model. Tumor growth delay was measured at a volume of 500 mm3. Results: Both lines were radiosensitized by ABT alone, and ABT further increased chemotherapy dose-modifying factors to the 1.6 to 1.8 range. All combinations were synergistic (combination indices <0.9). ABT treatment significantly increased DSB after RT (?H2AX, 69% vs 43%; P=.017) and delayed repair. We found tumor growth delays of 7.22 days for RT; 11.90 days for RT and ABT; 13.5 days for oxaliplatin, RT, and ABT; 14.17 days for 5-fluorouracil, RT, and ABT; and 23.81 days for irinotecan, RT, and ABT. Conclusion: ABT-888 radiosensitizes at similar or higher levels compared with classic chemotherapies and acts synergistically with these chemotherapies to enhance RT effects. In vivo confirmation of these results indicates a potential role for combining its use with existing chemoradiation regimens

  19. In Vitro and In Vivo Enhancement of Chemoradiation Using the Oral PARP Inhibitor ABT-888 in Colorectal Cancer Cells

    Energy Technology Data Exchange (ETDEWEB)

    Shelton, Joseph W., E-mail: jwshelt@emory.edu [Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Waxweiler, Timothy V.; Landry, Jerome; Gao, Huiying; Xu, Yanbo; Wang, Lanfang [Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); El-Rayes, Bassel [Department of Hematology and Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Shu, Hui-Kuo G. [Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States)

    2013-07-01

    Purpose: Poly(ADP-ribose) polymerase plays a critical role in the recognition and repair of DNA single-strand breaks and double-strand breaks (DSBs). ABT-888 is an orally available inhibitor of this enzyme. This study seeks to evaluate the use of ABT-888 combined with chemotherapy and radiation therapy (RT) in colorectal carcinoma models. Methods and Materials: RT clonogenic assays were performed on HCT116 and HT29 cells treated with 5-fluorouracil, irinotecan, or oxaliplatin with or without ABT. The surviving fraction at 2 Gy and dose-modifying factor at 10% survival were analyzed. Synergism was assessed by isobologram analysis for combination therapies. ?H2AX and neutral comet assays were performed to assess the effect of therapy on DSB formation/repair. In vivo assessments were made by use of HCT116 cells in a xenograft mouse model. Tumor growth delay was measured at a volume of 500 mm{sup 3}. Results: Both lines were radiosensitized by ABT alone, and ABT further increased chemotherapy dose-modifying factors to the 1.6 to 1.8 range. All combinations were synergistic (combination indices <0.9). ABT treatment significantly increased DSB after RT (?H2AX, 69% vs 43%; P=.017) and delayed repair. We found tumor growth delays of 7.22 days for RT; 11.90 days for RT and ABT; 13.5 days for oxaliplatin, RT, and ABT; 14.17 days for 5-fluorouracil, RT, and ABT; and 23.81 days for irinotecan, RT, and ABT. Conclusion: ABT-888 radiosensitizes at similar or higher levels compared with classic chemotherapies and acts synergistically with these chemotherapies to enhance RT effects. In vivo confirmation of these results indicates a potential role for combining its use with existing chemoradiation regimens.

  20. Peripheral and central nervous system inhibition of 11?-hydroxysteroid dehydrogenase type 1 in man by the novel inhibitor ABT-384.

    Science.gov (United States)

    Katz, D A; Liu, W; Locke, C; Jacobson, P; Barnes, D M; Basu, R; An, G; Rieser, M J; Daszkowski, D; Groves, F; Heneghan, G; Shah, A; Gevorkyan, H; Jhee, S S; Ereshefsky, L; Marek, G J

    2013-01-01

    ABT-384 is a potent, selective inhibitor of 11-beta-hydroxysteroid dehydrogenase type 1 (HSD-1). One milligram of ABT-384 daily fully inhibited hepatic HSD-1. Establishing the dose that fully inhibits central nervous system (CNS) HSD-1 would enable definitive clinical studies in potential CNS indications. [9,11,12,12-(2)H4] cortisol (D4 cortisol), a stable labeled tracer, was used to characterize HSD-1 inhibition by ABT-384. D4 cortisol and its products were measured in the plasma and cerebrospinal fluid (CSF) of healthy male volunteers during D4 cortisol infusions, for up to 40 h after five daily doses of 1-50 mg ABT-384. Similar procedures were conducted in control subjects who received no ABT-384. Peripheral HSD-1 inhibition was calculated from plasma levels of D4 cortisol and its products. CNS HSD-1 inhibition was characterized from plasma and CSF levels of D4 cortisol and its products. ABT-384 regimens ?2 mg daily maintained peripheral HSD-1 inhibition ?88%. ABT-384 1 mg daily maintained peripheral HSD-1 inhibition ?81%. No CNS formation of D3 cortisol (the mass-labeled product of HSD-1) was detected following ABT-384 ?2 mg daily, indicating full CNS HSD-1 inhibition by these regimens. Partial CNS HSD-1 inhibition was associated with 1 mg ABT-384 daily. CNS HSD-1 inhibition was characterized by strong hysteresis and increased with maximum post-dose plasma concentration of ABT-384 and its active metabolites. ABT-384 has a wide potential therapeutic window for potential indications including Alzheimer's disease and major depressive disorder. Stable labeled substrates may be viable tools for measuring CNS effect during new drug development for other enzyme targets. PMID:23982627

  1. Determination of total antioxidant capacity of milk by CUPRAC and ABTS methods with separate characterisation of milk protein fractions.

    Science.gov (United States)

    Çekiç, Sema Demirci; Demir, Asl?; Ba?kan, Kevser Sözgen; Tütem, Esma; Apak, Re?at

    2015-05-01

    Most milk-applied antioxidant assays in literature are based on the isolation and quantification of individual antioxidative compounds, whereas total antioxidant capacity (TAC) gives a more holistic picture due to cooperative action of antioxidants. Recently, the cupric reducing antioxidant capacity (CUPRAC) method has been modified to measure the antioxidant capacities of thiol-containing proteins, where the classical ammonium acetate buffer - that may otherwise precipitate proteins- was replaced with concentrated urea buffer (able to expose embedded thiol groups of proteins to oxidative attack) adjusted to pH 7.0. Thus, antioxidant capacity of milk was investigated with two competing TAC assays, namely CUPRAC and ABTS (2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonic acid))/persulphate, because only these assays were capable of evaluating protein contribution to the observed TAC value. As milk fat caused turbidity, experiments were carried out with skim milk or defatted milk samples. To determine TAC, modified CUPRAC method was applied to whole milk, separated and redissolved protein fractions, and the remaining liquid phase after necessary operations. Both TAC methods were investigated for their dilution sensitivity and antioxidant power assessment of separate milk fractions such as casein and whey. Proteins like ?-lactoglobulin and casein (but not simple thiols) exhibited enhanced CUPRAC reactivity with surfactant (SDS) addition. Addition of milk protein fractions to whole skim milk produced significant 'negative-biased' deviations (up to -26% relative standard error) from TAC absorbance additivity in the application of the ABTS method, as opposed to that of the CUPRAC method less affected by chemical deviations from Beer's law thereby producing much smaller deviations from additivity (i.e. the property of additivity is valid when the measured TAC of a mixture is equal to the sum of individual antioxidant capacities of its constituents). PMID:25731579

  2. Ellagic acid, vitamin C, and total phenolic contents and radical scavenging capacity affected by freezing and frozen storage in raspberry fruit.

    Science.gov (United States)

    de Ancos, B; González, E M; Cano, M P

    2000-10-01

    The ellagic acid, total phenolic, and vitamin C contents in four raspberry cultivars (Heritage, Autumn Bliss, Rubi, and Zeva) grown in Spain were detected and quantified by HPLC in fresh, just frozen, and stored fruits at -20 degrees C for a one year period. Ellagic acid [207-244 mg kg(-)(1) of fresh weight (fw)], total phenolic (137-1776 mg kg(-)(1) of fw), and vitamin C (221-312 mg kg(-)(1) of fw) contents in raw material were higher in the late cultivars Zeva and Rubi than in the early cultivars Autumn Bliss and Heritage. The freezing process slightly affected the values of extracted ellagic acid, total phenolic, and vitamin C content. At the end of long-term frozen storage (12 months), no significant change of total phenolic content extracted was observed, but significant decreases of 14-21% in ellagic acid and of 33-55% in vitamin C were quantified. Free radical scavenging capacity measured as antiradical efficiency (AE) depends on the seasonal period of harvest. Late cultivars, Rubi (6.1 x 10(-)(4)) and Zeva (10.17 x 10(-)(4)), showed higher AE than early cultivars, Heritage (4.02 x 10(-)(4)) and Autumn Bliss (4.36 x 10(-)(4)). The freezing process produced a decrease of AE values in the four cultivars ranging between 4 and 26%. During the frozen storage, the AE values reached after the freezing process remained unchanged. PMID:11052701

  3. Estudio comparativo sobre la capacidad de atrapamiento del catiónradical ABTS+. Por los aceites esenciales de especies aromáticas con alto contenido de trans-ANETOL Y ESTRAGOL

    Directory of Open Access Journals (Sweden)

    Amner Mu\\u00F1oz

    2007-01-01

    Full Text Available Se determinó la composición química de aceites esenciales (AEs y extractos de seis especies aromáticas con alto contenido de trans-anetol y estragol (estragón de invierno, estragón, anís estrellado, anisillo, hinojo y sígueme morado, obtenidos por hidrodestilación asistida por radiación de microondas (MWHD y destilación-extracción simultánea con solvente (SDE. La separación e identificación de los compuestos se realizó por GC-MS en columna apolar DB-5MS, comparando sus espectros de masas con los de las bases de datos ADAMS, NIST02 y Wiley138 e índices de retención de kovàts. Para todos los AEs se evaluó su capacidad del atrapamiento del catión-radical ABTS+. (ácido 2,2? -azino-bis -(3-etiltiazolina-bencenosulfónico-6.

  4. Evaluation of in vitro antioxidant activity and free radical scavenging potential of variety of Tagetes erecta L. flowers growing in Bulgaria

    Directory of Open Access Journals (Sweden)

    Yuliana Markovska

    2012-08-01

    Full Text Available Summary. Marigold (Tagetes erecta L. is well known for its antimicrobial, antiseptic, wound and ulcer healing, antiinflammatory, antioxidant and antiviral properties, and it has a long history of being used as an herbal remedy. T. erecta L. produces a variety of substances that possess pharmacological effects and antioxidant activity. The present study was therefore aimed to analyze the antioxidant activity of extracts and fractions of T. erecta L. flowers, cultivated in Bulgaria. Radical scavenging potential was determined using two different in vitro assays. 1, 1-diphenyl-2-picrylhydrazyl (DPPH and 2, 2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS radicals. The ethyl acetate fraction of T. erecta L. ethanol extract was found to be the most effective in both assays, DPPH (IC50 4.3±0.4 ?g/ml and ABTS (0.8±0.2 TEAC. The greatest total phenolic content was detected in EtOAc fraction from EtOH extract (517.8 mg/g GAE. It was obtained high quantity of ascorbate and ascorbate/dehydroascorbate ratio more than 1. The quantity of glutathione reduced is low and glutathione reduced/glutathione oxidized ratio was lower than 1. A correlation between radical scavenging capacities of samples with total phenolic compound content was observed. The present study revealed that the EtOAc fraction effectively show the best ability to scavenge the free radicals. Industrial relevance. Herbal medicines have gained increasing attention worldwide for the treatment of chronic diseases because of their effectiveness and small side effects as compared to synthetic drugs.Recently, an attention has been directed toward the antioxidant phytochemicals which have proved as protective against cardiovascular diseases and cancer, associated with overproduction of reactive oxygen species. The present investigations focus has been to discover plant extracts and fractions from T. erecta useful to prevent chronic degenerative diseases, especially those mediated by free radicals damages. The great antioxidant activity indicates the potential of the extracts as a source of natural antioxidants or nutraceuticals with possible application to reduce oxidative stress with consequent health benefits. Keywords. Tagetes erecta L.; in vitro antioxidant activity; free radical scavenging potential; phenols; flavonoids; ascorbate, glutathione.

  5. Striatal dopamine level contributes to hydroxyl radical generation and subsequent neurodegeneration in the striatum in 3-nitropropionic acid-induced Huntington's disease in rats.

    Science.gov (United States)

    Pandey, Mritunjay; Borah, Anupom; Varghese, Merina; Barman, Pijus Kanti; Mohanakumar, Kochupurackal P; Usha, Rajamma

    2009-11-01

    We tested the hypothesis that dopamine contributes significantly to the hydroxyl radical (OH)-induced striatal neurotoxicity caused by 3-nitropropionic acid (3-NP) in a rat model of Huntington's disease. Dopamine (10-100 microM) or 3-NP (10-1000 microM) individually caused a significant increase in the generation of hydroxyl radical (OH) in the mitochondria, which was synergistically enhanced when the lowest dose of the neurotoxin (10 microM) and dopamine (100 microM) were present together. Similarly, systemic administration of l-DOPA (100-250 mg/kg) and a low dose of 3-NP (10 mg/kg) potentiated OH generation in the striatum, and the rats exhibited significant decrease in stride length, a direct indication of neuropathology. The pathology was also evident in striatal sections subjected to NeuN immunohistochemistry. The significant changes in stride length, the production of striatal OH and neuropathological features due to administration of a toxic dose of 3-NP (20 mg/kg) were significantly attenuated by treating the rats with tyrosine hydroxylase inhibitor alpha-methyl-p-tyrosine prior to 3-NP administration. These results strongly implicate a major contributory role of striatal dopamine in increased generation of OH, which leads to striatal neurodegeneration and accompanied behavioral changes, in 3-NP model of Huntington's disease. PMID:19410615

  6. Reaction of sulphate radical anion (SO{sub 4}{sup {center_dot}}{sup -}) with cyanuric acid. A potential reaction for its degradation?

    Energy Technology Data Exchange (ETDEWEB)

    Manoj, P.; Varghese, R.; Manoj, V.M.; Aravindakumar, C.T. [Mahatma Gandhi University, School of Chemical Sciences, Kottayam (India)

    2002-01-01

    A novel reaction between sulfate radical anion (SO{sub 4}{sup {center_dot}}{sup -}) and cyanuric acid (CA), a non-degradable end product of the oxidative degradation of the triazine based herbicide, atrazine, is presented using laser flash photolysis and steady state radiolysis techniques at pH 5. A second order rate constant of 1.9x10{sup 7} dm{sup 3} mol{sup -1} s{sup -1} has been determined and the transient intermediate ({lambda}{sub max}=330 nm) is assigned to a radical cation of CA (CA{sup {center_dot}}{sup +}). The degradation profile indicated that about 76% of CA have been decomposed after an absorbed {gamma}-radiation dose of 18 kGy. It is therefore proposed that the reaction of SO{sub 4}{sup {center_dot}}{sup -} could be utilised for the degradation of CA in aqueous medium which is normally stable to any Advanced Oxidation Processes. (author)

  7. A pulse radiolysis study of the reactions of OH radical/O-with linoleic acid in the oxygen-free aqueous solution

    International Nuclear Information System (INIS)

    Absorption spectra of products resulting from the reaction of OH radical and O- with linoleate in an aqueous solution have been measured. An OH radical adduct, absorbing at approx. 240 nm, as well as the allyl and the dienyl radical, were observed. The dienyl radical is formed by the reaction of linoleate with OH radical and O- radicals. The greater selectivity for the formation of dienyl radicals by O- as compared to OH radical is due to the formation of an OH radical adduct. The dependence of the absorption band of the adduct on linoleate concentration can be explained in terms of competition between reactions of OH radical with linoleate molecules in micelles and in solution. It is assumed that OH radicals neither form adducts nor dienyl radicals with micellized linoleate, but still react with these molecules, albeit in a different way. Since the rate constant for the reaction of OH radical with micellized linoleate is comparable to the rate constant for the OH radical addition reaction and much lower than the rate constant for dienyl production, the absorbance at 280 nm (dienyl) is less affected by the linoleate concentration increase than the absorbance at approx. 240 nm (OH adduct). (author)

  8. Nitrogen Oxides in the Nocturnal Boundary Layer: Chemistry of Nitrous Acid (HONO) and the Nitrate Radical (N03)

    Energy Technology Data Exchange (ETDEWEB)

    Jochen Stutz

    2005-05-24

    Summary Chemical processes occurring at night in the lowest part of the urban atmosphere, the so called nocturnal boundary layer (NBL), can influence the composition of the atmosphere during the night as well as the following day. They may impact the budgets of some of the most important pollutants, such as ozone and nitrogen oxides, as well as influence size and composition of particular matter. Few studies have thus far concentrated on the nocturnal chemistry of the urban NBL, most likely due to the strong influence of vertical transport and mixing, which requires the measurement of trace gas profiles instead of simple point observations. Motivated by our lack of observations and understanding of nocturnal chemistry, the focus of this project was the study of the vertical distribution of trace gases and the altitude dependence of nocturnal chemistry under polluted conditions through field observations and modeling studies. The analysis of three field experiments (TEXAQS, Houston, 2000; Phoenix Sunrise Ozone Experiment, 2001; NAPOX, Boston, 2002), two of which were performed in this project, showed that ozone concentrations typically increase with height in the lowest 150m, while NO2 typically decreases. NO3, the dominant nocturnal radical species, showed much higher concentrations in the upper part of the NBL, and was often not present at the ground. With the help of a one-dimensional chemical transport model, developed in this project, we found that the interaction of ground emissions of NOx and hydrocarbons, together with their vertical transport, is responsible for the vertical profiles. The dominant chemical reactions influencing ozone, NO2 and NO3 are the reaction of ozone and NO3 with freshly emitted NO. Sensitivity studies with our model showed that the magnitude of the trace gas gradients depend both on the emission rates and the vertical stability of the NBL. Observations and model analysis clearly show that nocturnal chemistry in urban areas is altitude dependent. Measurements at one altitude, for example at the ground, where most air quality monitoring stations are located, are not representative for the rest of the NBL. Our model also revealed that radical chemistry is, in general, altitude dependent at night. We distinguish three regions: an unreactive, NO rich, ground layer; an upper, O3 and NO3 dominated layer, and a reactive mixing layer, where RO2 radicals are mixed from aloft with NO from the ground. In this reactive layer an active radical chemistry and elevated OH radical levels can be found. The downward transport of N2O5 and HO2NO2, followed by their thermal decay, was also identified as a radical source in this layer. Our observations also gave insight into the formation of HONO in the NBL. Based on our field experiments we were able to show that the NO2 to HONO conversion was relative humidity dependent. While this fact was well known, we found that it is most likely the uptake of HONO onto surfaces which is R.H. dependent, rather than the NO2 to HONO conversion. This finding led to the proposal of a new NO2 to HONO conversion mechanism, which is based on solid physical chemical principles. Noteworthy is also the observation of enhanced NO2 to HONO conversion during a dust storm event in Phoenix. The final activity in our project investigated the influence of the urban canopy, i.e. building walls and surfaces, on nocturnal chemistry. For the first time the surface area of a city was determined based on a Geographical Information System database of the city of Santa Monica. The surface to volume areas found in this study showed that, in the 2 lower part of the NBL, buildings provide a much larger surface area than the aerosol. In addition, buildings take up a considerable amount of the volume near the ground. The expansion of our model and sensitivity studies based on the Santa Monica data revealed that the surface area of buildings considerably influences HONO levels in urban areas. The volume reduction leads to a decrease of O3 and an increase of NO2 near the ground due to the stronger impact o

  9. The effects of ABT-491 administration on visual evoked potentials in rat model of hypoxic ischemic brain injury - Original Article

    Directory of Open Access Journals (Sweden)

    Tolgay Ergeno?lu

    2010-12-01

    Full Text Available Aim: In the present study, we aimed to investigate the effects of ABT-491 on visual evoked potentials (VEP in rat model of hypoxic ischemic brain injury (HIBI. Material and Method: Fifty-seven male Wistar newborn rats were used in this study. Animals were divided into three groups randomly. HIBI was formed on postnatal seventh day according to modified Levine-Rice model in 1st (n=18 and 2nd (n=20 groups. Third group (n=19 served as sham group. After HIBI, ABT-491 was applied intraperitoneally to rats in the 1st group (ABT group and saline was administered to the rats in the 2nd group (saline group. On postnatal 16th weeks, VEPs were recorded from Ag-AgCl disc electrode placed on the occipital region. Results: The latencies of P3 wave were shorter in the ABT group than the saline group (p<0.05. Peak-to-peak amplitudes of P2-N2 and N2-P3 were smaller in the ABT and saline groups compared to the sham group (for all pairwise comparisons p<0.001.Conclusions:It was concluded that HIBI caused a decrement in amplitudes of VEP responses and this change could not be ameliorated with ABT-491. However, shortening in latencies of P3 wave could be ameliorated with ABT-491 treatment after HIBI was formed. (Turk Arch Ped 2010; 45: 319-23

  10. Free-Radical Scavenging Properties and Reducing Power of Grape Cane Extracts from 11 Selected Grape Cultivars Widely Grown in China

    Directory of Open Access Journals (Sweden)

    Ang Zhang

    2011-12-01

    Full Text Available Total phenolic contents (TPC, total flavonoid contents (TFC, related antioxidative and antiradical capabilities of grape cane extracts from 11 varieties (five V. vinifera cultivars and six Chinese wild grapes widely grown in China were evaluated. Antioxidant properties were determined as DPPH and ABTS radical-scavenging abilities, superoxide anion and hydroxyl radical and hydrogen peroxide scavenging assays, as well as reducing power. Phenolic profiles of the extracts were characterized by using high-performance liquid chromatography (HPLC techniques. All extracts exhibited strong antioxidant and effective free radical inhibition activities (EC50 values, which generally correlated negatively with TPC (r = ?0.804 to ?0.918 and TFC (r = ?0.749 to ?0.888. In comparison with gallic acid, Trolox and tert-butylhydroquinone (positive controls, most grape cane extracts showed more efficient scavenging effects toward different reactive oxygen species. HPLC analysis revealed the presence of (+-catechin, (?-epicatechin, and trans-resveratrol as major phenolic components in the extracts. These results suggest that grape cane extracts may serve as a potential source of natural antioxidant for food and pharmaceutical application.

  11. Phenolic acid content and radical scavenging activity of extracts from medlar (Mespilus germanica L.) fruit at different stages of ripening.

    Czech Academy of Sciences Publication Activity Database

    Grúz, Ji?í; Ayaz, F. A.; Torun, H.; Strnad, Miroslav

    2011-01-01

    Ro?. 124, ?. 1 (2011), s. 271-277. ISSN 0308-8146 R&D Projects: GA AV ?R KAN200380801 Institutional research plan: CEZ:AV0Z50380511 Keywords : Phenolic acid s * HPLC * Mass spectrometry * Fruit * Ripening Subject RIV: EF - Botanics Impact factor: 3.655, year: 2011

  12. The Effect of Methyl, Hydroxyl, and Ketone Functional Groups on the Heterogeneous Oxidation of Succinic Acid Aerosol by OH Radicals

    Science.gov (United States)

    Chan, M.; Zhang, H.; Wilson, K. R.

    2013-12-01

    The heterogeneous oxidation of atmospheric organic aerosols can influence their effects on climate, human health, and visibility. During oxidation, functionalization occurs when an oxygenated functional group is added to a molecule, leaving the carbon skeleton intact. Fragmentation involves carbon-carbon bond cleavage and produces two products with smaller carbon numbers than the parent compound. To gain better insights into how the molecular structure of more oxygenated organic compounds affects heterogeneous reactivity, succinic acid aerosols are photo-oxidized in an aerosol flow tube reactor, and the reaction products are analyzed using Direct Analysis in Real Time Mass Spectrometry for online chemical analysis. The effect of various functional groups (CH3, OH, C=O) along the carbon backbone on the heterogeneous reaction mechanisms are also investigated using model compounds. For this series of compounds, the formation of more oxygenated products through functionalization can be explained by well-known condensation-phase reactions such as Russell and Bennett and Summers. The number of fragmentation products is found to increase with the presence of OH and CH3 groups. This can be attributed to the increased number of tertiary carbons, enhancing the fragmentation after multiple oxidation steps. Smaller dicaids (oxalic acid and malonic acid) can be formed through the fragmentation processes in the heterogeneous oxidation of succinic acid. The effect of molecular structure on reaction kinetics, volatilization, and the relative importance of functionalization and fragmentation pathways will be discussed.

  13. Peripheral and central nervous system inhibition of 11?-hydroxysteroid dehydrogenase type 1 in man by the novel inhibitor ABT-384

    OpenAIRE

    Katz, D. A.; Liu, W.; Locke, C.; Jacobson, P.; Barnes, D. M.; Basu, R.; An, G.; Rieser, M. J.; Daszkowski, D.; Groves, F.; Heneghan, G.; Shah, A.; Gevorkyan, H.; Jhee, S. S.; Ereshefsky, L.

    2013-01-01

    ABT-384 is a potent, selective inhibitor of 11-beta-hydroxysteroid dehydrogenase type 1 (HSD-1). One milligram of ABT-384 daily fully inhibited hepatic HSD-1. Establishing the dose that fully inhibits central nervous system (CNS) HSD-1 would enable definitive clinical studies in potential CNS indications. [9,11,12,12-2H4] cortisol (D4 cortisol), a stable labeled tracer, was used to characterize HSD-1 inhibition by ABT-384. D4 cortisol and its products were measured in the plasma and cerebrosp...

  14. ANTIOXIDANT CAPACITY AND AMINO ACID PROFILES OF EGG TOFU

    Directory of Open Access Journals (Sweden)

    Maizura Murad

    2013-01-01

    Full Text Available Tofu contains high quality protein source and antioxidant which could reduce risk of cancer. This research aims to determine the effect of soymilk and egg ratios on the antioxidant capacity, daidzein and genistein content and amino acid profiles of egg tofu. Egg tofu was prepared using soymilk and fresh egg in ratios of 1:1, 2:1, 3:1 and 4:1. Glucono-Delta-Lactone (GDL was added in the egg tofu to act as a coagulating agent. Increased of soymilk at all ratios had significantly (p<0.05 increased in Ferric-Reducing Antioxidant Power (FRAP, daidzein and genistein content of egg tofu. Conversely, decreased in soymilk ratio had significantly (p<0.05 increased the radical scavenging activities of the 2,2-Azino-Bis 3-ethylbenzothiazoline-6-Sulfonic acid (ABTS and 2,2-Diphenyl-2-Picrylhydrazyl (DPPH in egg tofu. Increased of soymilk ratio up to 3:1 caused decreased in amino acid methionine (met and cystein (cys significantly (p<0.05. A significant (p<0.01 and a positive correlation was observed between Total Phenolic Content (TPC and FRAP (r = 0.93. However, there was a negative (p<0.01 correlation between TPC and DPPH (r = -0.83. The antioxidant capacity of egg tofu in DPPH assay showed a positive and significant (p<0.01 correlation with cysteine, methionine and tryptophan with r value of 0.92, 0.93 and 0.96 respectively. Higher content of egg in egg tofu had contributed to the increased of antioxidant capacity as indicated in DPPH assay and ABTS assay as well as amino acid methionine and cysteine.

  15. Changes in optical density, amino acid composition, and fluorescence of papain inactivated by hydroxyl radicals and hydrogen peroxide

    International Nuclear Information System (INIS)

    Chromatography of irradiated papain on an affinity column with the Gly-Gly-Tyr(Bzl)-Arg inhibitor peptide gave rise to three clearly resolved peaks. The first one was relatively small and contained completely inactive nonreparable enzyme, which appeared to have suffered a massive conformational change or loss of several binding sites. The second contained the inactive sulfenic acid derivative, which can be reactivated with cysteine. The third peak was composed of nonrepairable enzyme as well as some repairable enzyme and some fully active papain. Changes in absorbance and amino acid analysis established a significant loss of tyrosine residues, while tryptophan destruction appeared to be insignificant up to 10 krad. Fluorescence measurements indicated changes in the active-site region, which are probably largely due to the inactivating modification of the Cys-25 sulfhydryl group, for which evidence has already been reported

  16. Modeling nitrous acid and its impact on ozone and hydroxyl radical during the Texas Air Quality Study 2006

    OpenAIRE

    Czader, B. H.; Rappenglu?ck, B.; Percell, P.; Byun, D. W.; Ngan, F.; Kim, S.

    2012-01-01

    Nitrous acid (HONO) mixing ratios for the Houston metropolitan area were simulated with the Community Multiscale Air Quality (CMAQ) model for an episode during the Texas Air Quality Study (TexAQS) II in August/September 2006 and compared to in-situ MC/IC (mist-chamber/ion chromatograph) and long path DOAS (Differential Optical Absorption Spectroscopy) measurements at three different altitudes. Several HONO sources were accounted for in simulations, such as gas phase formation, direct emission...

  17. The BH3 mimetic ABT-737 increases treatment efficiency of paclitaxel against hepatoblastoma

    OpenAIRE

    Fuchs Jörg; Warmann Steven W; Kirchner Bettina; Wenz Julia; Eicher Carmen; Lieber Justus; Armeanu-Ebinger Sorin

    2011-01-01

    Abstract Background The primary goal of current chemotherapy in hepatoblastoma (HB) is reduction of tumour volume and vitality to enable complete surgical resection and reduce risk of recurrence or metastatic disease. Drug resistance remains a major challenge for HB treatment. In some malignancies inhibition of anti-apoptotic pathways using small BH3 mimetic molecules like ABT-737 shows synergistic effects in combination with cystotoxic agents in vitro. Now we analysed toxicology and synergis...

  18. The BH3 mimetic ABT-737 increases treatment efficiency of paclitaxel against hepatoblastoma

    Directory of Open Access Journals (Sweden)

    Fuchs Jörg

    2011-08-01

    Full Text Available Abstract Background The primary goal of current chemotherapy in hepatoblastoma (HB is reduction of tumour volume and vitality to enable complete surgical resection and reduce risk of recurrence or metastatic disease. Drug resistance remains a major challenge for HB treatment. In some malignancies inhibition of anti-apoptotic pathways using small BH3 mimetic molecules like ABT-737 shows synergistic effects in combination with cystotoxic agents in vitro. Now we analysed toxicology and synergistic effects of this approach in HB cells and HB xenografts. Methods Viability was monitored in HB cells (HUH6 and HepT1 and fibroblasts treated with paclitaxel, ABT-737 and a combination of both in a MTT assay. HUH6 xenotransplants in NOD/LtSz-scid IL2R?null mice (NSG were treated accordingly. Tumour volume and body weight were monitored. Xenografted tumours were analysed by histology and immunohistochemistry (Ki-67 and TUNEL assay. Results ABT-737 reduced viability in HUH6 and HepT1 cells cultures at concentrations above 1 ?M and also enhanced the cytotoxic effect of paclitaxel when used in combination. Thereby paclitaxel could be reduced tenfold to achieve similar reduction of viability of tumour cells. In contrast no toxicity in fibroblasts was observed at the same regiments. Subcutaneous HB (HUH6 treated with paclitaxel (12 mg/kg body weight, n = 7 led to delayed tumour growth in the beginning of the experiment. However, tumour volume was similar to controls (n = 5 at day 25. Combination treatment with paclitaxel and ABT-737 (100 mg/kg, n = 8 revealed significantly 10 fold lower relative tumour volumes compared to control and paclitaxel groups. Paclitaxel dependent toxicity was observed in this mice strain. Conclusions Our results demonstrate enhancement of chemotherapy by using modulators of apoptosis. Further analyses should include improved pharmacological formulations of paclitaxel and BH3 mimetics in order to reduce toxicological effects. Sensitising HB to apoptosis may also render resistant HB susceptible to established chemotherapy regimens.

  19. The BH3 mimetic ABT-737 increases treatment efficiency of paclitaxel against hepatoblastoma

    Science.gov (United States)

    2011-01-01

    Background The primary goal of current chemotherapy in hepatoblastoma (HB) is reduction of tumour volume and vitality to enable complete surgical resection and reduce risk of recurrence or metastatic disease. Drug resistance remains a major challenge for HB treatment. In some malignancies inhibition of anti-apoptotic pathways using small BH3 mimetic molecules like ABT-737 shows synergistic effects in combination with cystotoxic agents in vitro. Now we analysed toxicology and synergistic effects of this approach in HB cells and HB xenografts. Methods Viability was monitored in HB cells (HUH6 and HepT1) and fibroblasts treated with paclitaxel, ABT-737 and a combination of both in a MTT assay. HUH6 xenotransplants in NOD/LtSz-scid IL2R?null mice (NSG) were treated accordingly. Tumour volume and body weight were monitored. Xenografted tumours were analysed by histology and immunohistochemistry (Ki-67 and TUNEL assay). Results ABT-737 reduced viability in HUH6 and HepT1 cells cultures at concentrations above 1 ?M and also enhanced the cytotoxic effect of paclitaxel when used in combination. Thereby paclitaxel could be reduced tenfold to achieve similar reduction of viability of tumour cells. In contrast no toxicity in fibroblasts was observed at the same regiments. Subcutaneous HB (HUH6) treated with paclitaxel (12 mg/kg body weight, n = 7) led to delayed tumour growth in the beginning of the experiment. However, tumour volume was similar to controls (n = 5) at day 25. Combination treatment with paclitaxel and ABT-737 (100 mg/kg, n = 8) revealed significantly 10 fold lower relative tumour volumes compared to control and paclitaxel groups. Paclitaxel dependent toxicity was observed in this mice strain. Conclusions Our results demonstrate enhancement of chemotherapy by using modulators of apoptosis. Further analyses should include improved pharmacological formulations of paclitaxel and BH3 mimetics in order to reduce toxicological effects. Sensitising HB to apoptosis may also render resistant HB susceptible to established chemotherapy regimens. PMID:21854558

  20. Activities of ABT-773 against Listeria monocytogenes and coryneform bacteria of clinical interest.

    Science.gov (United States)

    Conejo, María del Carmen; Martínez-Martínez, Luis; Pascual, Alvaro; Suárez, Ana Isabel; Perea, Evelio J

    2003-04-01

    The in vitro activities of ABT-773 were evaluated against 15 Listeria monocytogenes strains and 196 coryneform bacteria isolated from clinical samples. One hundred percent of the L. monocytogenes strains were inhibited by amycolatum), 1 and >32 (Corynebacterium jeikeium), 0.03 and >32 (Corynebacterium minutissimum), >32 and >32 (Corynebacterium pseudodiphtheriticum and Corynebacterium urealyticum), 0.125 and >32 (Corynebacterium striatum), and 0.03 and 0.5 (Rhodococcus equi), respectively. PMID:12654678

  1. Growth of ABT-5 bacteria culture in whey supplemented with whey protein concentrate

    Directory of Open Access Journals (Sweden)

    Bojan Matijevi?

    2010-09-01

    Full Text Available The objective of this research was to decrease the duration of whey fermentation and to analyze the impact of whey protein concentrates (WPC addition on growth and activity as well as on survival of mixed ABT-5 culture bacteria (Lactobacillus acidophilus, Bifidobacterium spp. and Streptococcus thermophilus during 28 days of fermented whey cold storage (5 °C. Whey fermentation was observed at 37 °C with and without 1.5 and 3 % WPC addition. Whey fermentation with mixed ABT-5 bacterial culture took about 6.5 hours, and WPC did not affect the fermentation dynamics, regardless of the added amount. The viable cell count of Lactobacillus acidophilus was higher in fermented whey with WPC (about 7.13 log CFU/mL compared to whey without WPC (about 6.63 log CFU/mL. WPC addition did not affect the growth of bacteria Bifidobacterium spp. and Streptococcus thermophilus nor the survival of ABT-5 culture bacteria in fermented whey during 28 days of cold storage (5 °C.

  2. Dosimetry in the megarad range by means of ESR-spectroscopy on free radicals of amino acids

    International Nuclear Information System (INIS)

    Starting from the difficulties in determining doses in the range from 10 krd to 1 Mrd using conventional measuring techniques which are based on optical signals, a non-optical dosimetry technique is described using the paramagnetic absorption of irradiated organic materials whose approximate tissue equivalence allows widely energy independent dose determinations. On the example of the amino acid alanine, dosimetrical details are given and practical experiences with this technique are reported, such as dose-effect relationship, sensitivity scattering within a larger collection of detectors and signal loss with storage time. (author)

  3. Celecoxib-induced apoptosis is enhanced by ABT-737 and by inhibition of autophagy in human colorectal cancer cells

    OpenAIRE

    Huang, Shengbing; Sinicrope, Frank A.

    2010-01-01

    Apoptosis and autophagy have been shown to be negatively regulated by prosurvival Bcl-2 proteins. We determined whether the anticancer agent celecoxib, alone or combined with a small molecule Bcl-2/Bcl-xL antagonist (ABT-737), can induce autophagy in colon cancer cells. Furthermore, we determined whether inhibition of autophagy can drive colon cancer cells into apoptosis. Celecoxib was shown to induce apoptosis that was attenuated by ectopic Bcl-2 or Bax knockout. ABT-737 synergistically enha...

  4. Phase I Study of PARP Inhibitor ABT-888 in Combination with Topotecan in Adults with Refractory Solid Tumors and Lymphomas

    OpenAIRE

    Kummar, Shivaani; Chen, Alice; Ji, Jiuping; Zhang, Yiping; Reid, Joel M.; Ames, Matthew; Jia, Lee; Weil, Marcie; Speranza, Giovanna; Murgo, Anthony J.; Kinders, Robert; Wang, Lihua; Parchment, Ralph E.; Carter, John; Stotler, Howard

    2011-01-01

    A phase I trial of ABT-888 (veliparib), a poly(ADP-ribose) polymerase (PARP inhibitor), in combination with topotecan, a topoisomerase I–targeted agent, was performed to determine maximum tolerated dose (MTD), safety, pharmacokinetics, and pharmacodynamics of the combination in patients with refractory solid tumors and lymphomas. Varying schedules and doses of intravenous topotecan in combination with ABT-888 (10 mg) administered orally twice a day (BID) were evaluated. Plasma and urine pha...

  5. In vitro antioxidant properties, free radicals scavenging activities of extracts and polyphenol composition of a non-timber forest product used as spice: Monodora myristica

    Scientific Electronic Library Online (English)

    Bruno Moukette, Moukette; Constant Anatole, Pieme; Jacques Romain, Njimou; Cabral Prosper Nya, Biapa; Bravi, Marco; Jeanne Yonkeu, Ngogang.

    Full Text Available BACKGROUND: Excessive production of free radicals causes direct damage to biological molecules such as DNA, proteins, lipids, carbohydrates leading to tumor development and progression. Natural antioxidant molecules from phytochemicals of plant origin may directly inhibit either their production or [...] limit their propagation or destroy them to protect the system. In the present study, Monodora myristica a non-timber forest product consumed in Cameroon as spice was screened for its free radical scavenging properties, antioxidant and enzymes protective activities. Its phenolic compound profile was also realized by HPLC. RESULTS: This study demonstrated that M. myristica has scavenging properties against DPPH',OH',NO', and ABTS'radicals which vary in a dose depending manner. It also showed an antioxidant potential that was comparable with that of Butylated Hydroxytoluene (BHT) and vitamin C used as standard. The aqueous ethanol extract of M. myristica barks (AEH); showed a significantly higher content in polyphenolic compounds (21.44 ±0.24 mg caffeic acid/g dried extract) and flavonoid (5.69 ± 0.07 quercetin equivalent mg/g of dried weight) as compared to the other studied extracts. The HPLC analysis of the barks and leaves revealed the presence of several polyphenols. The acids (3,4-OH-benzoic, caffeic, gallic, O- and P- coumaric, syringic, vanillic), alcohols (tyrosol and OH-tyrosol), theobromine, quercetin, rutin, catechine and apigenin were the identified and quantified polyphenols. All the tested extracts demonstrated a high protective potential on the superoxide dismutase (SOD), catalase and peroxidase activities. CONCLUSION: Finally, the different extracts from M. myristica and specifically the aqueous ethanol extract reveal several properties such as higher free radical scavenging properties, significant antioxidant capacities and protective potential effects on liver enzymes.

  6. Radical Catalysis.

    Czech Academy of Sciences Publication Activity Database

    Jahn, Ullrich

    Weinheim : Wiley-VCH, 2013 - (Cornils, B.; Herrmann, W.; Wong, C.; Zanthoff, H.), s. 1894-1895 ISBN 978-3-527-33307-3 Institutional support: RVO:61388963 Keywords : radicals * homogeneous catalysis * single-electron transfer * oxidative addition * ligand transfer Subject RIV: CC - Organic Chemistry

  7. Redox properties of free radicals

    International Nuclear Information System (INIS)

    Results of electron transfer reactions observed and monitored by pulse radiolysis are reported. This technique allows determination of the first one-electron reduction or oxidation of a compound rather than the overall two-electron transfer usually reported. Pulse radiolysis allows the determination of absolute rate constants for reactions of free radicals and helps elucidate the mechanisms involved. Studies using this technique to study radicals derived from quinones, nitro compounds, pyridines, phenols, and anilines are reported. Radicals of biochemical interest arising from riboflavin, ascorbic acid, vitamin K3, vitamin E, MAD+, porphyrins, etc. have also been studied

  8. Grafting of Poly(methyl methacrylate Brushes from Magnetite Nanoparticles Using a Phosphonic Acid Based Initiator by Ambient Temperature Atom Transfer Radical Polymerization (ATATRP

    Directory of Open Access Journals (Sweden)

    Babu Kothandapani

    2008-01-01

    Full Text Available AbstractPoly(methyl methacrylate in the brush form is grown from the surface of magnetite nanoparticles by ambient temperature atom transfer radical polymerization (ATATRP using a phosphonic acid based initiator. The surface initiator was prepared by the reaction of ethylene glycol with 2-bromoisobutyrl bromide, followed by the reaction with phosphorus oxychloride and hydrolysis. This initiator is anchored to magnetite nanoparticles via physisorption. The ATATRP of methyl methacrylate was carried out in the presence of CuBr/PMDETA complex, without a sacrificial initiator, and the grafting density is found to be as high as 0.90 molecules/nm2. The organic–inorganic hybrid material thus prepared shows exceptional stability in organic solvents unlike unfunctionalized magnetite nanoparticles which tend to flocculate. The polymer brushes of various number average molecular weights were prepared and the molecular weight was determined using size exclusion chromatography, after degrafting the polymer from the magnetite core. Thermogravimetric analysis, X-ray photoelectron spectra and diffused reflection FT-IR were used to confirm the grafting reaction.

  9. Preclinical discovery of candidate genes to guide pharmacogenetics during phase I development: the example of the novel anticancer agent ABT-751

    Science.gov (United States)

    Innocenti, Federico; Ramírez, Jacqueline; Obel, Jennifer; Xiong, Julia; Mirkov, Snezana; Chiu, Yi-Lin; Katz, David A.; Carr, Robert A.; Zhang, Wei; Das, Soma; Adjei, Araba; Moyer, Ann M.; Chen, Pei Xian; Krivoshik, Andrew; Medina, Diane; Gordon, Gary B.; Ratain, Mark J.; Sahelijo, Leonardo; Weinshilboum, Richard M.; Fleming, Gini F.; Bhathena, Anahita

    2013-01-01

    Objective ABT-751, a novel orally available antitubulin agent, is mainly eliminated as inactive glucuronide (ABT-751G) and sulfate (ABT-751S) conjugates. We performed a pharmacogenetic investigation of ABT-751 pharmacokinetics using in-vitro data to guide the selection of genes for genotyping in a phase I trial of ABT-751. Methods UDP-glucuronosyltransferase (UGT) and sulfotransferase (SULT) enzymes were screened for ABT-751 metabolite formation in vitro. Forty-seven cancer patients treated with ABT-751 were genotyped for 21 variants in these genes. Results UGT1A1, UGT1A4, UGT1A8, UGT2B7, and SULT1A1 were found to be involved in the formation of inactive ABT-751 glucuronide (ABT-751G) and sulfate (ABT-751S). SULT1A1 copy number (> 2) was associated with an average 34% increase in ABT-751 clearance (P= 0.044), an 18% reduction in ABT-751 AUC (P = 0.045), and a 50% increase in sulfation metabolic ratios (P=0.025). UGT1A8 rs6431558 was associated with a 28% increase in glucuronidation metabolic ratios (P =0.022), and UGT1A4*2 was associated with a 65% decrease in ABT-751 Ctrough (P = 0.009). Conclusion These results might represent the first example of a clinical pharmacokinetic effect of the SULT1A1 copy number variant on the clearance of a SULT1A1 substrate. A-priori selection of candidate genes guided by in-vitro metabolic screening enhanced our ability to identify genetic determinants of interpatient pharmacokinetic variability. PMID:23670235

  10. Radical versus non-radical inventions

    OpenAIRE

    Schoenmakers, Wilfred; Duysters, Geert; Vanhaverbeke, Wim

    2008-01-01

    This paper looks at the special characteristics of radical inventions. It tries to identify those variables that differentiate radical inventions from non-radical inventions. Since radical inventions are very important for the economy as a whole and for the individual firm performances, understanding what makes radical inventions differ from non-radical inventions is very important. For our research we made use of the EPO (European Patent Office) database on patents. We used...

  11. Enzyme-bound pentadienyl and peroxyl radicals in purple lipoxygenase

    International Nuclear Information System (INIS)

    Samples of purple lipoxygenase prepared by addition of either 13-hydroperoxy-9,11-octadecadienoic acid or linoleic acid and oxygen to ferric lipoxygenase contain pentadienyl and/or peroxyl radicals. The radicals are identified by the g values and hyperfine splitting parameters of natural abundance and isotopically enriched samples. The line shapes of their EPR spectra suggest the radicals are conformationally constrained when compared to spectra of the same radicals generated in frozen linoleic acid. Further, the EPR spectra are unusually difficult to saturate. All of this implies that these species are bound to the enzyme, possibly in proximity to the iron. Addition of natural abundance hydroperoxide under 17O-enriched O2 leads to the 17O-enriched peroxyl radical, while the opposite labeling results in the natural abundance peroxyl radical, demonstrating the exchange of oxygen. Both radicals are detected in samples of purple lipoxygenase prepared with either linoleic acid or hydroperoxide under air. Addition of the hydroperoxide in the absence of oxygen favors the pentadienyl radical. The authors propose that addition of either linoleic acid or hydroperoxide to ferric lipoxygenase leads to multiple mechanistically connected enzyme complexes, including those with (hydro)peroxide, peroxide, peroxyl radical, pentadienyl radical, and linoleic acid bound. This hypothesis is essentially identical with the proposed radical mechanism of oxygeth the proposed radical mechanism of oxygenation of polyunsaturated fatty acids by lipoxygenase

  12. Pharmacological properties and procognitive effects of ABT-288, a potent and selective histamine H3 receptor antagonist.

    Science.gov (United States)

    Esbenshade, Timothy A; Browman, Kaitlin E; Miller, Thomas R; Krueger, Kathleen M; Komater-Roderwald, Victoria; Zhang, Min; Fox, Gerard B; Rueter, Lynne; Robb, Holly M; Radek, Richard J; Drescher, Karla U; Fey, Thomas A; Bitner, R Scott; Marsh, Kennan; Polakowski, James S; Zhao, Chen; Cowart, Marlon D; Hancock, Arthur A; Sullivan, James P; Brioni, Jorge D

    2012-10-01

    Blockade of the histamine H(3) receptor (H(3)R) enhances central neurotransmitter release, making it an attractive target for the treatment of cognitive disorders. Here, we present in vitro and in vivo pharmacological profiles for the H(3)R antagonist 2-[4'-((3aR,6aR)-5-methyl-hexahydro-pyrrolo[3,4-b]pyrrol-1-yl)-biphenyl-4-yl]-2H-pyridazin-3-one (ABT-288). ABT-288 is a competitive antagonist with high affinity and selectivity for human and rat H(3)Rs (K(i) = 1.9 and 8.2 nM, respectively) that enhances the release of acetylcholine and dopamine in rat prefrontal cortex. In rat behavioral tests, ABT-288 improved acquisition of a five-trial inhibitory avoidance test in rat pups (0.001-0.03 mg/kg), social recognition memory in adult rats (0.03-0.1 mg/kg), and spatial learning and reference memory in a rat water maze test (0.1-1.0 mg/kg). ABT-288 attenuated methamphetamine-induced hyperactivity in mice. In vivo rat brain H(3)R occupancy of ABT-288 was assessed in relation to rodent doses and exposure levels in behavioral tests. ABT-288 demonstrated a number of other favorable attributes, including good pharmacokinetics and oral bioavailability of 37 to 66%, with a wide central nervous system and cardiovascular safety margin. Thus, ABT-288 is a selective H(3)R antagonist with broad procognitive efficacy in rodents and excellent drug-like properties that support its advancement to the clinical area. PMID:22815533

  13. {sup 3}H-labeling of prokinetic motilide ABT-229 for biodistribution and metabolism studies

    Energy Technology Data Exchange (ETDEWEB)

    Faghih, Ramin; Burnell-Curty, Cynthia; Surber, Bruce; Shoghi, Simin; Borre, Anthony; Ye Yao; Lartey, P.A.; Nellans, H.N. [Abbott Labs., Pharmaceutical Discovery, Abbott Park, IL (United States)

    1996-07-01

    The prokinetic drug candidate, ABT-229, has been successfully [{sup 3}H]-labeled in the macrolactone ring. This was accomplished with [{sup 3}H]-NaBH{sub 4} reduction of the 11-ketone analog in a four step synthetic sequence beginning with the drug candidate. The {sup 3}H-labeled drug was obtained with specific activity of 9.0 Ci/mmol and radiochemical purity > 99%. This constitutes the first methodology for {sup 3}H-labeling of the macrolactone in an erythromycin derivative. (author).

  14. 3H-labeling of prokinetic motilide ABT-229 for biodistribution and metabolism studies

    International Nuclear Information System (INIS)

    The prokinetic drug candidate, ABT-229, has been successfully [3H]-labeled in the macrolactone ring. This was accomplished with [3H]-NaBH4 reduction of the 11-ketone analog in a four step synthetic sequence beginning with the drug candidate. The 3H-labeled drug was obtained with specific activity of 9.0 Ci/mmol and radiochemical purity > 99%. This constitutes the first methodology for 3H-labeling of the macrolactone in an erythromycin derivative. (author)

  15. Activation of dopamine D4 receptors by ABT-724 induces penile erection in rats

    OpenAIRE

    Brioni, Jorge D.; Moreland, Robert B.; Cowart, Marlon; Hsieh, Gin C.; Stewart, Andrew O.; Hedlund, Petter; Donnelly-roberts, Diana L.; Nakane, Masaki; Lynch, James J.; Kolasa, Teodozyi; Polakowski, James S.; Osinski, Mark A.; Marsh, Kennan; Andersson, Karl-erik; Sullivan, James P.

    2004-01-01

    Apomorphine, a nonselective dopamine receptor agonist, facilitates penile erection and is effective in patients suffering from erectile dysfunction. The specific dopamine receptor subtype(s) responsible for its erectogenic effect is not known. Here we report that the dopamine D4 receptor plays a role in the regulation of penile function. ABT-724 is a selective dopamine D4 receptor agonist that activates human dopamine D4 receptors with an EC50 of 12.4 nM and 61% efficacy, with no effect on do...

  16. Synthesis and Biological Evaluation of New 1,3-Thiazolidine-4-one Derivatives of 2-(4-Isobutylphenylpropionic Acid

    Directory of Open Access Journals (Sweden)

    Ioana Mirela Vasincu

    2014-09-01

    Full Text Available New thiazolidine-4-one derivatives of 2-(4-isobutylphenylpropionic acid (ibuprofen have been synthesized as potential anti-inflammatory drugs. The structure of the new compounds was proved using spectral methods (FR-IR, 1H-NMR, 13C-NMR, MS. The in vitro antioxidant potential of the synthesized compounds was evaluated according to the total antioxidant activity, the DPPH and ABTS radical scavenging assays. Reactive oxygen species (ROS and free radicals are considered to be involved in many pathological events like diabetes mellitus, neurodegenerative diseases, cancer, infections and more recently, in inflammation. It is known that overproduction of free radicals may initiate and amplify the inflammatory process via upregulation of genes involved in the production of proinflammatory cytokines and adhesion molecules. The chemical modulation of acyl hydrazones of ibuprofen 3a–l through cyclization to the corresponding thiazolidine-4-ones 4a–n led to increased antioxidant potential, as all thiazolidine-4-ones were more active than their parent acyl hydrazones and also ibuprofen. The most active compounds are the thiazolidine-4-ones 4e, m, which showed the highest DPPH radical scavenging ability, their activity being comparable with vitamin E.

  17. Role of p38 MAPK in enhanced human cancer cells killing by the combination of aspirin and ABT-737.

    Science.gov (United States)

    Zhang, Chong; Shi, Jing; Mao, Shi-ying; Xu, Ya-si; Zhang, Dan; Feng, Lin-yi; Zhang, Bo; Yan, You-you; Wang, Si-cong; Pan, Jian-ping; Yang, You-ping; Lin, Neng-ming

    2015-02-01

    Regular use of aspirin after diagnosis is associated with longer survival among patients with mutated-PIK3CA colorectal cancer, but not among patients with wild-type PIK3CA cancer. In this study, we showed that clinically achievable concentrations of aspirin and ABT-737 in combination could induce a synergistic growth arrest in several human PIK3CA wild-type cancer cells. In addition, our results also demonstrated that long-term combination treatment with aspirin and ABT-737 could synergistically induce apoptosis both in A549 and H1299 cells. In the meanwhile, short-term aspirin plus ABT-737 combination treatment induced a greater autophagic response than did either drug alone and the combination-induced autophagy switched from a cytoprotective signal to a death-promoting signal. Furthermore, we showed that p38 acted as a switch between two different types of cell death (autophagy and apoptosis) induced by aspirin plus ABT-737. Moreover, the increased anti-cancer efficacy of aspirin combined with ABT-737 was further validated in a human lung cancer A549 xenograft model. We hope that this synergy may contribute to failure of aspirin cancer therapy and ultimately lead to efficacious regimens for cancer therapy. PMID:25388762

  18. Chemical Constituents with Free-Radical-Scavenging Activities from the Stem of Microcos paniculata

    OpenAIRE

    Yu Chen; Xiang-Ming Liu; Tong Zheng; Zhi-Nan Mei; Guang-Zhong Yang; Su Chen; Hua Fan

    2010-01-01

    The free-radical-scavenging activities of various solvent extracts of Microcos paniculata were evaluated through in vitro model systems, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and Co (II) EDTA-induced luminol chemiluminescence by flow injection. In all three of these systems the ethyl acetate (EtOAc) extract showed the highest free-radical-scavenging activity compared with the other three (n-BuOH, water and petroleum ether) ext...

  19. The chemistry of peroxy radicals and its implication to radiation biology

    International Nuclear Information System (INIS)

    A review is presented of peroxy radical chemistry and its implication for radiation biology, using the techniques of pulse and steady-state radiolysis. The subject is dealt with in sections, entitled: electron transfer reactions from free radicals; the superoxide radical .02-; formation and detection of organic peroxy radicals; acid-base properties of peroxy radicals; stability of organic peroxy radicals; reactions of electron adducts and O2; slow reactions of radicals and oxygen; decay kinetics of peroxy radicals; intermediates of peroxy radical reactions; formation of hydroperoxides; peroxy radicals and molecular radiation biology; lethality in presence of oxygen; repair of damage. (author)

  20. Strong Inhibition of O-Atom Transfer Reactivity for Mn(IV)(O)(?-Radical-Cation)(Lewis Acid) versus Mn(V)(O) Porphyrinoid Complexes.

    Science.gov (United States)

    Zaragoza, Jan Paulo T; Baglia, Regina A; Siegler, Maxime A; Goldberg, David P

    2015-05-27

    The oxygen atom transfer (OAT) reactivity of two valence tautomers of a Mn(V)(O) porphyrinoid complex was compared. The OAT kinetics of Mn(V)(O)(TBP8Cz) (TBP8Cz = octakis(p-tert-butylphenyl)corrolazinato(3-)) reacting with a series of triarylphosphine (PAr3) substrates were monitored by stopped-flow UV-vis spectroscopy, and revealed second-order rate constants ranging from 16(1) to 1.43(6) × 10(4) M(-1) s(-1). Characterization of the OAT transition state analogues Mn(III)(OPPh3)(TBP8Cz) and Mn(III)(OP(o-tolyl)3)(TBP8Cz) was carried out by single-crystal X-ray diffraction (XRD). A valence tautomer of the closed-shell Mn(V)(O)(TBP8Cz) can be stabilized by the addition of Lewis and Brønsted acids, resulting in the open-shell Mn(IV)(O)(TBP8Cz(•+)):LA (LA = Zn(II), B(C6F5)3, H(+)) complexes. These Mn(IV)(O)(?-radical-cation) derivatives exhibit dramatically inhibited rates of OAT with the PAr3 substrates (k = 8.5(2) × 10(-3) - 8.7 M(-1) s(-1)), contrasting the previously observed rate increase of H-atom transfer (HAT) for Mn(IV)(O)(TBP8Cz(•+)):LA with phenols. A Hammett analysis showed that the OAT reactivity for Mn(IV)(O)(TBP8Cz(•+)):LA is influenced by the Lewis acid strength. Spectral redox titration of Mn(IV)(O)(TBP8Cz(•+)):Zn(II) gives Ered = 0.69 V vs SCE, which is nearly +700 mV above its valence tautomer Mn(V)(O)(TBP8Cz) (Ered = -0.05 V). These data suggest that the two-electron electrophilicity of the Mn(O) valence tautomers dominate OAT reactivity and do not follow the trend in one-electron redox potentials, which appear to dominate HAT reactivity. This study provides new fundamental insights regarding the relative OAT and HAT reactivity of valence tautomers such as M(V)(O)(porph) versus M(IV)(O)(porph(•+)) (M = Mn or Fe) found in heme enzymes. PMID:25964988

  1. Reaction between protein radicals and other biomolecules

    DEFF Research Database (Denmark)

    Østdal, Henrik; Davies, Michael Jonathan

    2002-01-01

    The present study investigates the reactivity of bovine serum albumin (BSA) radicals towards different biomolecules (urate, linoleic acid, and a polypeptide, poly(Glu-Ala-Tyr)). The BSA radical was formed at room temperature through a direct protein-to-protein radical transfer from H(2)O(2)-activated immobilized horseradish peroxidase (im-HRP). Subsequently, each of the three different biomolecules was separately added to the BSA radicals, after removal of im-HRP by centrifugation. Electron spin resonance (ESR) spectroscopy showed that all three biomolecules quenched the BSA radicals. Subsequent analysis showed a decrease in the concentration of urate upon reaction with the BSA radical, while the BSA radical in the presence of poly(Glu-Ala-Tyr) resulted in increased formation of the characteristic protein oxidation product, dityrosine. Reaction between the BSA radical and a linoleic acid oil-in-water emulsion resulted in additional formation of lipid hydroperoxides and conjugated dienes. The results clearly show that protein radicals have to be considered as dynamic species during oxidative processes in biological systems and that protein radicals should not be considered as end-products, but rather as reactive intermediates during oxidative processes in biological systems hereby supporting recent data.

  2. Mathematical Evaluation of the Amino Acid and Polyphenol Content and Antioxidant Activities of Fruits from Different Apricot Cultivars

    Directory of Open Access Journals (Sweden)

    Rene Kizek

    2011-09-01

    Full Text Available Functional foods are of interest because of their significant effects on human health, which can be connected with the presence of some biologically important compounds. In this study, we carried out complex analysis of 239 apricot cultivars (Prunus armeniaca L. cultivated in Lednice (climatic area T4, South Moravia, Czech Republic. Almost all previously published studies have focused only on analysis of certain parameters. However, we focused on detection both primary and secondary metabolites in a selection of apricot cultivars with respect to their biological activity. The contents of thirteen biogenic alpha-L-amino acids (arginine, asparagine, isoleucine, lysine, serine, threonine, valine, leucine, phenylalanine, tryptophan, tyrosine, proline and alanine were determined using ion exchange chromatography with UV-Vis spectrometry detection. Profile of polyphenols, measured as content of ten polyphenols with significant antioxidant properties (gallic acid, procatechinic acid, p-aminobenzoic acid, chlorogenic acid, caffeic acid, vanillin, p-coumaric acid, rutin, ferrulic acid and quercetrin, was determined by high performance liquid chromatography with spectrometric/electrochemical detection. Moreover, content of total phenolics was determined spectrophotometrically using the Folin-Ciocalteu method. Antioxidant activity was determined using five independent spectrophotometric methods: DPPH assay, DMPD method, ABTS method, FRAP and Free Radicals methods. Considering the complexity of the obtained data, they were processed and correlated using bioinformatics techniques (cluster analysis, principal component analysis. The studied apricot cultivars were clustered according to their common biochemical properties, which has not been done before. The observed similarities and differences were discussed.

  3. Formation of semiquinone radical anion and free radical scavenging reactions of plumbagin. A pulse radiolysis study

    International Nuclear Information System (INIS)

    Kinetics and mechanism of scavenging of reducing free radicals by plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) are studied using pulse radiolysis technique. It scavenged superoxide radical, hydroxyethyl radical and hydrated electron with bimolecular rate constants of 8.9 × 107, 2.3 × 109 and 1.6 × 1010 M-1 s-1, respectively in aqueous-alcohol medium. Plumbagin also scavenged linoleic acid peroxyl radical and tyrosyl radical with bimolecular rate constants of 1.0 × 108 and 7.0 × 106 M-1 s-1, respectively. Further, redox properties of plumbagin and its transients are studied using standard redox couples and cyclic voltammetry. (author)

  4. High-molar-mass hyaluronan behavior during testing its radical scavenging capacity in organic and aqueous media: effects of the presence of manganese(II) ions.

    Science.gov (United States)

    Rapta, Peter; Valachová, Katarína; Gemeiner, Peter; Soltés, Ladislav

    2009-02-01

    This study compares the radical scavenging capacity of high-molar-mass hyaluronan (HA) using standardized methods applying 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and 2,2'-azinobis[3-ethylbenzthiazoline sulfonate] (ABTS) radical cations as oxidants. Additionally, spin-trapping technique combined with electron paramagnetic resonance (EPR) was used to evaluate the ability of HA to scavenge reactive radicals. The thermal decomposition of K2S2O8 in pure H2O or in a H2O/dimethyl sulfoxide (DMSO) mixture at 333 K was used as a source of reactive paramagnetic species. We found that HA does not exhibit radical-scavenging activity when DPPH radicals or ABTS(.+) radical cations are used as oxidant, but that HA is an effective radical scavenger at low concentrations, if the oxidation reactions are initiated by the decomposition of K2S2O8. At higher HA concentrations, a more complex behavior and prooxidant HA action was observed. The influence of Mn(II) ions on the reaction mechanisms of radical generation and termination in the K2S2O8/H2O/DMSO system in the presence of HA was studied in detail. PMID:19235158

  5. Radical America

    Science.gov (United States)

    The journal Radical American began in 1967 and was started by the Alternative Education Project in Somerville, Massachusetts. Over their history, they have published a number of issues on a number of compelling topics, ranging from community development to feminism. As part of their Digital Initiatives Project, Brown University has digitized the first fourteen year print run of the journal up to the year 1980. Visitors here can browse the contents of the journal by author or by title. Some of these titles include pieces on American Leninism, Europe's migrant workers, and the "urban crisis" of the 1970s. Visitors can also browse the digitized volumes by clicking on an interactive page that contains the covers of the available issues. Overall, this is a fine resource for social historians and members of the public with a penchant for exploring some of the overlooked facets of contemporary American history.

  6. Radical Women

    Science.gov (United States)

    2012-07-13

    Created as part of the University of Florida Digital Collections program, the Radical Women exhibition "documents the valiant history of women in the Gainesville Women's Liberation Movement." The collection consists of photos, oral histories, self-published newsprints, newsletters, brochures, notes from feminist organizations, and other original documents. Visitors can perform an advanced search across all the items, search via text passages, and also just browse the All Items section. The documents here include scholarly appraisals of the feminist movement in Gainesville during the 1970s, newspaper clippings that provide historical perspective on the subject, and opinion pieces published during this period on a range of subjects related to the struggle for equal rights.

  7. Single- and multiple dose pharmacokinetics and multiple dose pharmacodynamics of oral ABT-116 (a TRPV1 antagonist) in dogs.

    Science.gov (United States)

    Niyom, S; Mama, K R; Gustafson, D L; Rezende, M L

    2015-08-01

    Six dogs were used to determine single and multiple oral dose pharmacokinetics of ABT-116. Blood was collected for subsequent analysis prior to and at 15, 30 min and 1, 2, 4, 6, 12, 18, and 24 h after administration of a single 30 mg/kg dose of ABT-116. Results showed a half-life of 6.9 h, kel of 0.1/h, AUC of 56.5 ?g·h/mL, Tmax of 3.7 h, and Cmax of 3.8 ?g/mL. Based on data from this initial phase, a dose of 10 mg/kg of ABT-116 (no placebo control) was selected and administered to the same six dogs once daily for five consecutive days. Behavioral observations, heart rate, respiratory rate, temperature, thermal and mechanical (proximal and distal limb) nociceptive thresholds, and blood collection were performed prior to and 4, 8, and 16 h after drug administration each day. The majority of plasma concentrations were above the efficacious concentration (0.23 ?g/mL previously determined for rodents) for analgesia during the 24-h sampling period. Thermal and distal limb mechanical thresholds were increased at 4 and 8 h, and at 4, 8, and 16 h respectively, postdosing. Body temperature increased on the first day of dosing. Results suggest adequate exposure and antinociceptive effects of 10 mg/kg ABT-116 following oral delivery in dogs. PMID:25376244

  8. Free Radical Scavenging Activity of Mussaenda glabra

    Directory of Open Access Journals (Sweden)

    K.S. Vidyalakshmi

    2006-01-01

    Full Text Available The flowers of Mussaenda glabra occurring in white and pink have been evaluated for their anti oxidant property. The white (MGW and the pink (MGP varieties showed considerable NO scavenging activity. The IC50 values were found to be 92.79 and 122.45 ?g mL-1, respectively. MGW inhibited lipid peroxidation to a greater extent when compared to MGP. MGW showed 50% inhibition at the concentration of 112.4 ?g mL-1 while MGP at 53.42 ?g mL-1. The reducing power was found in a dose dependent manner. The pink variety showed greater reducing power when compared to white variety. Both the extracts showed hydroxyl radical and ABTS radical scavenging property. The total phenolic content was 17.5 and 8.3 mg g-1 in MGP and MGW, respectively. The HPTLC fingerprinting showed peaks due to flavonoids. The results show that both are having considerable anti oxidant property. The abundance of this flower throughout the year can be used for evaluating its medicinal value.

  9. Targeting CDK9 by wogonin and related natural flavones potentiates the anti-cancer efficacy of the Bcl-2 family inhibitor ABT-263.

    Science.gov (United States)

    Polier, Gernot; Giaisi, Marco; Köhler, Rebecca; Müller, Wolfgang W; Lutz, Christoph; Buss, Eike C; Krammer, Peter H; Li-Weber, Min

    2015-02-01

    Tumor initiation, progression and resistance to therapies are tightly associated with over-expression of anti-apoptotic proteins Bcl-2, Bcl-x(L), Bcl-w and Mcl-1. ABT-263 (Navitoclax), an orally bio-available small-molecule mimetic of the Bcl-2 homology domain 3, inhibits Bcl-2, Bcl-x(L), and Bcl-w and has shown anti-cancer effects mainly on lymphomas and lymphocytic leukemia. Despite promising results obtained from the clinical trials, the use of ABT-263 in patients is dose-limited due to causing thrombocytopenia via inhibition of Bcl-x(L) in platelets. ABT-199 specifically inhibits Bcl-2; however, its use is limited to tumors over-expressing only Bcl-2. Besides, many tumors resist treatment due to high levels of Mcl-1 expression or develop resistance via up-regulation of Mcl-1 during long-term exposure. These obstacles highlight the demand to improve the ABT-263-based therapy. In this study, we show that anti-cancer flavones, e.g., wogonin, baicalein, apigenin, chrysin and luteolin enhance ABT-263-induced apoptosis in different cancer cell lines and in primary AML and ALL cells by down-regulation of Mcl-1 expression. Importantly, wogonin does not enhance the toxicity of ABT-263 to proliferating normal T cells and thrombocytes. Wogonin also potentiates the lethality of ABT-263 in cancer cells which have acquired resistance to ABT-263. Furthermore, we show that combination of wogonin with ABT-263 promotes in vivo tumor regression in a human T-cell leukemia xenograft mouse model. Our study demonstrates that wogonin (and related flavones) reduce the effective dose of ABT-263 thereby possibly decreasing the risk of adverse side effects. PMID:24895203

  10. Antioxidant activities and radical scavenging activities of flavonoids studied by the electrochemical methods and ESR technique based on the novel paramagnetic properties of poly(aniline-co-5-aminosalicylic acid)

    International Nuclear Information System (INIS)

    Graphical abstract: ESR spectra of the PAASA/RGO/graphite electrodes: (1) in the buffer solution consisting of 0.20 M phosphate and methanol (80: 20, v/v), (2) in the buffer solutions containing 150 ?M of (+)-catechin. -- Abstract: Four kinds of flavonoid, viz. flavanone naringenin, Flavone apigenin, flavonol kaempferol, and flavanol (+)-catechin, are used to investigate their antioxidant and radical scavenging activitis in the water-methanol solution of pH 6.3, using the electrochemical methods and electron spin resonance (ESR) technique. Poly(aniline-co-5-aminosalicylic acid) (PAASA) is first used as a radical source that was polymerized on a reduced graphene oxide (RGO)/glassy carbon (GC) disk or on the RGO/graphite fiber electrode. The assessment of the antioxidant activities is performed using both cyclic voltammetry and the open circuit potential measurement. On the basis of results from both electrochemical mathods, the order of the antioxidant actitvities of flavonoids is as follows: (+)-catechin > kaempferol > apigenin > naringenin However, the difference in the antioxidant activities between naringenin and apigenin is very small. On the basis of the ESR signal intensities of PAASA, the order of the radical scavenging activities of flavonoids is in good agreement with that of the above antioxdant activities.Three oxidation peaks on the cyclic voltammograms of (+)-catechin are first detected, which gives us a deep insight into the oxidation mechanism of (+)-catechin

  11. Radicals in Catalysis- Heterogeneous

    OpenAIRE

    GIAMELLO, Elio

    2002-01-01

    Several reactions in heterogeneous catalysis take place via radical intermediates. The present article illustrates the typical aspects of the radical chemistry in heterogeneous catalysis that very often differ from those in the radical chemistry in fluid homogeneous phases because of the role of the surface in the generation, stabilization, and transformation of radical species. The various routes for the formation of radicals on a surface will be taken into consideration including electron t...

  12. Pulse radiolysis and e.s.r. evidence for the formation of an alkene radical cation in aqueous solution

    International Nuclear Information System (INIS)

    Direct pulse radiolysis evidence, complemented by e.s.r. experiments, establishes that the radical cation Me2C+-radical CMe2 is formed by acid-catalysed elimination of OH-from radical CMe2CMe2OH; the radical cation deprotonates to give radical CH2CMe=CMe2 with k 3.9 x 105 S-1. (author)

  13. Pan-Mammalian Target of Rapamycin (mTOR) Inhibitor AZD8055 Primes Rhabdomyosarcoma Cells for ABT-737-induced Apoptosis by Down-regulating Mcl-1 Protein*

    Science.gov (United States)

    Preuss, Ellen; Hugle, Manuela; Reimann, Romy; Schlecht, Marcel; Fulda, Simone

    2013-01-01

    The PI3K/mammalian Target of Rapamycin (mTOR) pathway is often aberrantly activated in rhabdomyosarcoma (RMS) and represents a promising therapeutic target. Recent evaluation of AZD8055, an ATP-competitive mTOR inhibitor, by the Preclinical Pediatric Testing Program showed in vivo antitumor activity against childhood solid tumors, including RMS. Therefore, in the present study, we searched for AZD8055-based combination therapies. Here, we identify a new synergistic lethality of AZD8055 together with ABT-737, a BH3 mimetic that antagonizes Bcl-2, Bcl-xL, and Bcl-w but not Mcl-1. AZD8055 and ABT-737 cooperate to induce apoptosis in alveolar and embryonal RMS cells in a highly synergistic fashion (combination index < 0.2). Synergistic induction of apoptosis by AZD8055 and ABT-737 is confirmed on the molecular level, as AZD8055 and ABT-737 cooperate to trigger loss of mitochondrial membrane potential, activation of caspases, and caspase-dependent apoptosis that is blocked by the pan-caspase inhibitor Z-VAD-fmk. Similar to AZD8055, the PI3K/mTOR inhibitor NVP-BEZ235, the PI3K inhibitor NVP-BKM120 and Akt inhibitor synergize with ABT-737 to trigger apoptosis, whereas no cooperativity is found for the mTOR complex 1 inhibitor RAD001. Interestingly, molecular studies reveal a correlation between the ability of different PI3K/mTOR inhibitors to potentiate ABT-737-induced apoptosis and to suppress Mcl-1 protein levels. Importantly, knockdown of Mcl-1 increases ABT-737-induced apoptosis similar to AZD8055/ABT-737 cotreatment. This indicates that AZD8055-mediated suppression of Mcl-1 protein plays an important role in the synergistic drug interaction. By identifying a novel synergistic interaction of AZD8055 and ABT-737, our findings have important implications for the development of molecular targeted therapies for RMS. PMID:24133218

  14. Hydrogen bond network between amino acid radical intermediates on the proton-coupled electron transfer pathway of E. coli ?2 ribonucleotide reductase.

    Science.gov (United States)

    Nick, Thomas U; Lee, Wankyu; Kossmann, Simone; Neese, Frank; Stubbe, JoAnne; Bennati, Marina

    2015-01-14

    Ribonucleotide reductases (RNRs) catalyze the conversion of ribonucleotides to deoxyribonucleotides in all organisms. In all Class Ia RNRs, initiation of nucleotide diphosphate (NDP) reduction requires a reversible oxidation over 35 Å by a tyrosyl radical (Y122•, Escherichia coli) in subunit ? of a cysteine (C439) in the active site of subunit ?. This radical transfer (RT) occurs by a specific pathway involving redox active tyrosines (Y122 ? Y356 in ? to Y731 ? Y730 ? C439 in ?); each oxidation necessitates loss of a proton coupled to loss of an electron (PCET). To study these steps, 3-aminotyrosine was site-specifically incorporated in place of Y356-?, Y731- and Y730-?, and each protein was incubated with the appropriate second subunit ?(?), CDP and effector ATP to trap an amino tyrosyl radical (NH2Y•) in the active ?2?2 complex. High-frequency (263 GHz) pulse electron paramagnetic resonance (EPR) of the NH2Y•s reported the gx values with unprecedented resolution and revealed strong electrostatic effects caused by the protein environment. (2)H electron-nuclear double resonance (ENDOR) spectroscopy accompanied by quantum chemical calculations provided spectroscopic evidence for hydrogen bond interactions at the radical sites, i.e., two exchangeable H bonds to NH2Y730•, one to NH2Y731• and none to NH2Y356•. Similar experiments with double mutants ?-NH2Y730/C439A and ?-NH2Y731/Y730F allowed assignment of the H bonding partner(s) to a pathway residue(s) providing direct evidence for colinear PCET within ?. The implications of these observations for the PCET process within ? and at the interface are discussed. PMID:25516424

  15. Inhibition of Lipid Oxidation by MRP Antioxidant in Enriched Cooked Beef Patties with Polyunsaturated Fatty Acids

    Directory of Open Access Journals (Sweden)

    Carina Lorena Fernandez

    2012-05-01

    Full Text Available The addition of n3 polyunsaturated fatty acids to foods is an emerging area of commercial and academic interest. However, the incorporation of n3 polyunsaturated fatty acids into food systems is potentially problematic due to their propensity to oxidize easily. The antioxidant capacity of MRP has mostly been studied in vitro, in fresh chicken, mutton and pork, and in precooked ground pork and beef patties and sausages. The aim of this study is to evaluate the antioxidant properties as well as the antioxidant effect of a preformed Maillard Reaction Product (MRP from sarcoplasmic proteins/malondialdehyde, known for its antioxidant effect on water/oil emulsion and on lipid oxidation of beef patties when the level of n3 PUFA is improved. The MRP presented a high reducing power, a low phenolic compound content (9.2 mg gallic acid equivalent/g and 798.3 mg quercetin equivalent/g, and a minor DPPH and ABTS+ radicals scavenging activity (34 % and 23,5 %, respectively. All concentrations of MRP assayed inhibited hydroperoxide formation and thiobarbituric acid reactive substances (TBARS production during refrigerated storage of enriched meat patties. The 3% concentration was the most efficient and exerted an 83 % and 85 % inhibition of peroxidation measured as peroxide value and TBARS, respectively.

  16. Oral and cutaneous thermosensory profile of selective TRPV1 inhibition by ABT-102 in a randomized healthy volunteer trial

    DEFF Research Database (Denmark)

    Rowbotham, Michael C; Nothaft, Wolfram

    2011-01-01

    The capsaicin receptor (TRPV1) antagonist ABT-102 demonstrates efficacy in multiple preclinical pain models. However, evolving clinical data for this compound class suggest potentially profound drug-induced thermosensory impairment. Safety and tolerability of ABT-102 were assessed in a multiple-dose, double-blind, placebo-controlled, randomized healthy volunteer trial. Thirty-six participants were randomized in a 2:1 ratio to ABT-102:placebo in 3 dose groups (1mg, 2mg, and 4mg twice a day) and confined to an inpatient research unit for a 7-day treatment period and 3 follow-up days. Outcome measures included: oral and cutaneous cold detection, warm detection (WDT), and heat pain thresholds (HPT); oral perceived heat intensity (oral liquid test); time to hand withdrawal (water bath test); and cutaneous pain intensity (long thermal stimulus). Significant dose-dependent (placebo- and baseline-adjusted) increases in HPT and reduced painfulness of suprathreshold heat were present from days 1-7. For ABT-102 4mg twice a day, model-based mean differences from placebo (95% confidence interval) were as follows: oral HPT, day 1=2.5°C (0.6-4.4), day 5=4.4°C (2.5-6.3); cutaneous HPT, day 2=3.3°C (1.4-5.3), day 5=5.3°C (3.3-7.2); oral WDT, day 1=2.6°C (0.5-4.7), day 5=2.7°C (0.6-4.9); cutaneous WDT, day 2=1.3 (0.0-2.6), day 5=1.6 (0.3-2.8) (all P

  17. Two radical neuron doctrines

    OpenAIRE

    Hilbert, David R.; Byrne, Alex

    1999-01-01

    Two radical neuron doctrines must be distinguished--strong and weak. G&S direct much of their attack at the former--but the Churchlands only hold the latter. The weak radical neuron doctrine remains a serious possibility.

  18. Reactions of melatonin with radicals in deoxygenated aqueous solution

    International Nuclear Information System (INIS)

    Reactions of melatonin (N-acetyl-5-methoxytryptamine) with radiolytically generated radicals were studied. Reaction of melatonin with OH radicals is diffusion-controlled (k=1.2 x 1010 dm3 mol-1 x s-1), the main (but not the only one) intermediate being the indolyl-type radical, while the rate constant for the reaction with hydrated electrons is k=4.3 x 108 dm3 x mol-1 x s-1. Melatonin is capable of scavenging tert-butanol radicals, while its reactivity towards polymer radicals of poly(acrylic acid) and poly(vinyl pyrrolidone) is very low. (author)

  19. Lesson 28: Radical Equations

    Science.gov (United States)

    2011-01-01

    The lesson begins with an emphasis on isolating the radical expression in a radical equation and then highlights the importance of checking for extraneous solutions that may be generated when the equation is solved by applying even powers. Equations containing two radical expressions and then presented, followed by coverage of taking the nth root of a^n.

  20. Chemotherapeutic drugs sensitize human renal cell carcinoma cells to ABT-737 by a mechanism involving the Noxa-dependent inactivation of Mcl-1 or A1

    Directory of Open Access Journals (Sweden)

    Zantl Niko

    2010-06-01

    Full Text Available Abstract Background Human renal cell carcinoma (RCC is very resistant to chemotherapy. ABT-737 is a novel inhibitor of anti-apoptotic proteins of the Bcl-2 family that has shown promise in various preclinical tumour models. Results We here report a strong over-additive pro-apoptotic effect of ABT-737 and etoposide, vinblastine or paclitaxel but not 5-fluorouracil in cell lines from human RCC. ABT-737 showed very little activity as a single agent but killed RCC cells potently when anti-apoptotic Mcl-1 or, unexpectedly, A1 was targeted by RNAi. This potent augmentation required endogenous Noxa protein since RNAi directed against Noxa but not against Bim or Puma reduced apoptosis induction by the combination of ABT-737 and etoposide or vinblastine. At the level of mitochondria, etoposide-treatment had a similar sensitizing activity and allowed for ABT-737-induced release of cytochrome c. Conclusions Chemotherapeutic drugs can overcome protection afforded by Mcl-1 and A1 through endogenous Noxa protein in RCC cells, and the combination of such drugs with ABT-737 may be a promising strategy in RCC. Strikingly, A1 emerged in RCC cell lines as a protein of similar importance as the well-established Mcl-1 in protection against apoptosis in these cells.

  1. In Vitro Antioxidant Activities, Free Radical Scavenging Capacity, and Tyrosinase Inhibitory of Flavonoid Compounds and Ferulic Acid from Spiranthes sinensis (Pers.) Ames

    OpenAIRE

    Chung Pin Liang; Chia Hao Chang; Chien Cheng Liang; Kuei Yu Hung; Chang Wei Hsieh

    2014-01-01

    In this study, ultrasound-assisted extraction (UAE) and other methods of extracting flavonoid compounds and ferulic acid (FA) from S. sinensis were investigated. Five different extraction methods, including water extraction (W), water extraction using UAE (W+U), 75% ethanol extraction (E), 75% ethanol extraction using UAE (E+U), and supercritical CO2 extraction (SFE) were applied in the extraction of bioactive compounds (flavonoids and ferulic acid) in order to compare their efficiency. The h...

  2. Effect of Bucillamine on Free-Radical-Mediated Degradation of High-Molar-Mass Hyaluronan Induced in vitro by Ascorbic Acid and Cu(II Ions

    Directory of Open Access Journals (Sweden)

    Mária Ba?asová

    2014-10-01

    Full Text Available The bucillamine effect on free-radical-mediated degradation of high-molar-mass hyaluronan (HA has been elucidated. As HA fragmentation is expected to decrease its dynamic viscosity, rotational viscometry was applied to follow the oxidative HA degradation. Non-isothermal chemiluminometry, thermogravimetry, differential scanning calorimetry, and size-exclusion chromatography (SEC were applied to characterize resulting HA fragments. Although bucillamine completely inhibited the HA viscosity decrease caused by oxidative system, indicating HA protection from degradation, SEC analysis suggested that some other mechanisms leading to the bucillamine transformations without the decay of the viscosity may come into a play as well. Nonetheless, the link between the reduction of chemiluminescence intensity and disappearance of the differential scanning calorimetry exotherm at 270 °C for fragmented HAs indicates a particular role of the bucillamine in preventing the decrease of HA viscosity.

  3. Quantificação de compostos fenólicos e ácido ascórbico em frutos e polpas congeladas de acerola, caju, goiaba e morango / Quantification of phenolic compounds and ascorbic acid in fruits and frozen pulp of acerola, cashew, strawberry and guava

    Scientific Electronic Library Online (English)

    Juliana Mesquita, Freire; Celeste Maria Patto de, Abreu; Denise Alvarenga, Rocha; Angelita Duarte, Corrêa; Natália Rodrigues, Marques.

    2291-22-01

    Full Text Available O crescente interesse da população pela promoção da saúde vem despertando a atenção dos consumidores por alimentos ricos em antioxidantes, combinado com a praticidade do consumo de sucos de frutos processados. O presente trabalho objetivou quantificar e avaliar a capacidade antioxidante de compostos [...] fenólicos e ácido ascórbico em frutas in natura e polpas congeladas. As frutas in natura e polpas congeladas obtidas na região de Lavras - MG foram submetidas à quantificação de compostos fenólicos e ácido ascórbico e os respectivos extratos acetônico-etanólico e acetônico-metanólico. Foram determinadas suas atividades antioxidantes pelos métodos radicalares DPPH e ABTS. O extrato acetônico-metanólico foi mais efetivo para extrair os compostos antioxidantes das amostras. Apenas as polpas congeladas de acerola apresentaram uma redução do teor de compostos fenólicos em relação ao fruto. Para o teor de ácido ascórbico, houve uma redução nas polpas congeladas de acerola e goiaba. As amostras de acerola apresentaram os maiores teores de compostos fenólicos, ácido ascórbico e atividade antioxidante em relação aos demais frutos analisados. Abstract in english The growing public interest in health- promotion, has called the attention of consumers for foods rich in antioxidants, combined with the practicality of the consumption of processed fruit juices. Therefore, this study aimed to quantify and evaluate the antioxidant capacity of phenolic compounds and [...] ascorbic acid in fruits "in natura" and frozen pulps. The fruits "in natura" and frozen pulps from region of Lavras-MG, underwent quantification of phenolic compounds, ascorbic acid and the corresponding extracts acetonic-ethanolic and acetonic-methanolic. Their antioxidant activities were evaluated by DPPH and ABTS radical methods. The extract acetonic-methanolic was more effective to extract the antioxidant compounds from samples. Only frozen acerola pulps showed lower content of phenolic compounds in relation to fruit. For ascorbic acid, there was a reduction in the frozen pulp of acerola and guava. Acerola samples showed higher content of phenolic compounds, ascorbic acid and antioxidant activity compared to other fruits analyzed.

  4. Preparation and study of dialkyl nitroxide radicals

    International Nuclear Information System (INIS)

    These radicals are obtained by oxidation of N-hydroxy-imides with lead tetracetate or p-nitro-perbenzoic acid. These imides are prepared by heating dicarboxylic acids anhydrides with benzyloxy-amine followed by catalytic hydrogenation of N-benzyloxy-imides so obtained. Two series of radicals have mainly been studied, the first concerning five-membered cyclic imides, the second six-membered cyclic imides, these molecules having methyls substituents or no on the carbon ring. N. M. R. spectra of some O-benzyl-imides have been analysed. These different results have made it possible to study the conformation and stereochemistry of these imides. (author)

  5. BMX Acts Downstream of PI3K to Promote Colorectal Cancer Cell Survival and Pathway Inhibition Sensitizes to the BH3 Mimetic ABT-737

    Directory of Open Access Journals (Sweden)

    Danielle S. Potter

    2014-02-01

    Full Text Available Evasion of apoptosis is a hallmark of cancer, and reversing this process by inhibition of survival signaling pathways is a potential therapeutic strategy. Phosphoinositide 3-kinase (PI3K signaling can promote cell survival and is upregulated in solid tumor types, including colorectal cancer (CRC, although these effects are context dependent. The role of PI3K in tumorigenesis combined with their amenability to specific inhibition makes them attractive drug targets. However, we observed that inhibition of PI3K in HCT116, DLD-1, and SW620 CRC cells did not induce apoptotic cell death. Moreover, these cells were relatively resistant to the Bcl-2 homology domain 3 (BH3 mimetic ABT-737, which directly targets the Bcl-2 family of apoptosis regulators. To test the hypothesis that PI3K inhibition lowers the apoptotic threshold without causing apoptosis per se, PI3K inhibitors were combined with ABT-737. PI3K inhibition enhanced ABT-737-induced apoptosis by 2.3- to 4.5-fold and reduced expression levels of MCL-1, the resistance biomarker for ABT-737. PI3K inhibition enhanced ABT-737-induced apoptosis a further 1.4- to 2.4-fold in CRC cells with small interfering RNA-depleted MCL-1, indicative of additional sensitizing mechanisms. The observation that ABT-737-induced apoptosis was unaffected by inhibition of PI3K downstream effectors AKT and mTOR, implicated a novel PI3K-dependant pathway. To elucidate this, an RNA interference (RNAi screen of potential downstream effectors of PI3K signaling was conducted, which demonstrated that knockdown of the TEC kinase BMX sensitized to ABT-737. This suggests that BMX is an antiapoptotic downstream effector of PI3K, independent of AKT.

  6. BMX Acts Downstream of PI3K to Promote Colorectal Cancer Cell Survival and Pathway Inhibition Sensitizes to the BH3 Mimetic ABT-73712

    Science.gov (United States)

    Potter, Danielle S; Kelly, Paul; Denneny, Olive; Juvin, Veronique; Stephens, Len R; Dive, Caroline; Morrow, Christopher J

    2014-01-01

    Evasion of apoptosis is a hallmark of cancer, and reversing this process by inhibition of survival signaling pathways is a potential therapeutic strategy. Phosphoinositide 3-kinase (PI3K) signaling can promote cell survival and is upregulated in solid tumor types, including colorectal cancer (CRC), although these effects are context dependent. The role of PI3K in tumorigenesis combined with their amenability to specific inhibition makes them attractive drug targets. However, we observed that inhibition of PI3K in HCT116, DLD-1, and SW620 CRC cells did not induce apoptotic cell death. Moreover, these cells were relatively resistant to the Bcl-2 homology domain 3 (BH3) mimetic ABT-737, which directly targets the Bcl-2 family of apoptosis regulators. To test the hypothesis that PI3K inhibition lowers the apoptotic threshold without causing apoptosis per se, PI3K inhibitors were combined with ABT-737. PI3K inhibition enhanced ABT-737-induced apoptosis by 2.3- to 4.5-fold and reduced expression levels of MCL-1, the resistance biomarker for ABT-737. PI3K inhibition enhanced ABT-737-induced apoptosis a further 1.4- to 2.4-fold in CRC cells with small interfering RNA-depleted MCL-1, indicative of additional sensitizing mechanisms. The observation that ABT-737-induced apoptosis was unaffected by inhibition of PI3K downstream effectors AKT and mTOR, implicated a novel PI3K-dependant pathway. To elucidate this, an RNA interference (RNAi) screen of potential downstream effectors of PI3K signaling was conducted, which demonstrated that knockdown of the TEC kinase BMX sensitized to ABT-737. This suggests that BMX is an antiapoptotic downstream effector of PI3K, independent of AKT. PMID:24709422

  7. BMX acts downstream of PI3K to promote colorectal cancer cell survival and pathway inhibition sensitizes to the BH3 mimetic ABT-737.

    Science.gov (United States)

    Potter, Danielle S; Kelly, Paul; Denneny, Olive; Juvin, Veronique; Stephens, Len R; Dive, Caroline; Morrow, Christopher J

    2014-02-01

    Evasion of apoptosis is a hallmark of cancer, and reversing this process by inhibition of survival signaling pathways is a potential therapeutic strategy. Phosphoinositide 3-kinase (PI3K) signaling can promote cell survival and is upregulated in solid tumor types, including colorectal cancer (CRC), although these effects are context dependent. The role of PI3K in tumorigenesis combined with their amenability to specific inhibition makes them attractive drug targets. However, we observed that inhibition of PI3K in HCT116, DLD-1, and SW620 CRC cells did not induce apoptotic cell death. Moreover, these cells were relatively resistant to the Bcl-2 homology domain 3 (BH3) mimetic ABT-737, which directly targets the Bcl-2 family of apoptosis regulators. To test the hypothesis that PI3K inhibition lowers the apoptotic threshold without causing apoptosis per se, PI3K inhibitors were combined with ABT-737. PI3K inhibition enhanced ABT-737-induced apoptosis by 2.3- to 4.5-fold and reduced expression levels of MCL-1, the resistance biomarker for ABT-737. PI3K inhibition enhanced ABT-737-induced apoptosis a further 1.4- to 2.4-fold in CRC cells with small interfering RNA-depleted MCL-1, indicative of additional sensitizing mechanisms. The observation that ABT-737-induced apoptosis was unaffected by inhibition of PI3K downstream effectors AKT and mTOR, implicated a novel PI3K-dependant pathway. To elucidate this, an RNA interference (RNAi) screen of potential downstream effectors of PI3K signaling was conducted, which demonstrated that knockdown of the TEC kinase BMX sensitized to ABT-737. This suggests that BMX is an antiapoptotic downstream effector of PI3K, independent of AKT. PMID:24709422

  8. Efficacy and safety of the ?4?2 neuronal nicotinic receptor agonist ABT-894 in patients with diabetic peripheral neuropathic pain.

    Science.gov (United States)

    Rowbotham, Michael C; Arslanian, Armen; Nothaft, Wolfram; Duan, W Rachel; Best, Andrea E; Pritchett, Yili; Zhou, Qian; Stacey, Brett R

    2012-04-01

    Preclinical and clinical studies suggest that neuronal nicotinic receptor (NNR) agonists may be a novel and effective therapy for numerous painful conditions. Analgesic efficacy and safety of the highly selective ?(4)?(2) NNR agonist ABT-894 was evaluated in 2 separate randomized, double-blind, multicenter, placebo-controlled clinical trials in patients with diabetic peripheral neuropathic pain (DPNP). Study 1 (280 patients randomized) tested 1, 2, and 4 mg ABT-894 twice daily compared with placebo and 60 mg duloxetine once per day over 8 weeks of treatment. Study 2 (124 patients randomized) tested 6 mg ABT-894 twice daily vs placebo for 8 weeks. The primary efficacy outcome measure in both studies was the weekly mean of the 24-hour average pain score recorded in each patient's diary. In both trials, none of the ABT-894 dose groups showed efficacy compared with placebo, whereas duloxetine achieved a statistically significant improvement over placebo in Study 1. All dose levels of ABT-894 were well tolerated, and no significant safety issues were identified. These results are in contrast to the outcome of a previously reported study of DPNP using the less selective ?(4)?(2) NNR agonist ABT-594, which demonstrated efficacy compared with placebo, albeit with significant tolerability limitations. The failure of the highly selective ?(4)?(2) NNR agonist ABT-894 indicates that it may not be possible to define a therapeutic index for this mechanism or that selectively targeting ?(4)?(2) NNRs may not be a viable approach to treating neuropathic pain. PMID:22386472

  9. YM-155 potentiates the effect of ABT-737 in malignant human glioma cells via survivin and Mcl-1 downregulation in an EGFR-dependent context

    Science.gov (United States)

    Jane, Esther P.; Premkumar, Daniel R.; DiDomenico, Joseph D.; Hu, Bo; Cheng, Shi-Yuan; Pollack, Ian F.

    2013-01-01

    Antiapoptotic proteins are commonly overexpressed in gliomas, contributing to therapeutic resistance. We recently reported that clinically achievable concentrations of the Bcl-2/Bcl-xL inhibitor ABT-737 failed to induce apoptosis in glioma cells, with persistent expression of survivin and Mcl-1. To address the role of these mediators in glioma apoptosis resistance, we analyzed the effects of YM-155, a survivin suppressant, on survival on a panel of glioma cell lines. YM-155 inhibited growth, and downregulated survivin and Mcl-1 in a dose- and cell line-dependent manner. Whereas U373, LN18, LNZ428, T98G, LN229, and LNZ308 cells exhibited an IC50 of 10–75 nM, A172 cells were resistant (IC50 ~ 250 nM). No correlation was found between sensitivity to YM-155 and baseline expression of survivin or cIAP-1/cIAP-2/XIAP. However, strong correlation was observed between EGFR activation levels and YM-155 response, which was confirmed using EGFR-transduced versus wild-type cells. Because we postulated that decreasing Mcl-1 expression may enhance glioma sensitivity to ABT-737, we examined whether cotreatment with YM-155 promoted ABT-737 efficacy. YM-155 synergistically enhanced ABT-737-induced cytotoxicity and caspase-dependent apoptosis. Down-regulation of Mcl-1 using shRNA also enhanced ABT-737-inducing killing, confirming an important role for Mcl-1 in mediating synergism between ABT-737 and YM-155. As with YM-155 alone, sensitivity to YM-155 and ABT-737 inversely correlated with EGFR activation status. However, sensitivity could be restored in highly resistant U87-EGFRvIII cells by inhibition of EGFR or its downstream pathways, highlighting the impact of EGFR signaling on Mcl-1 expression and the relevance of combined targeted therapies to overcome the multiple resistance mechanisms of these aggressive tumors. PMID:23325792

  10. Setting the stage for electron transfer: Molecular basis of ABTS-binding to four laccases from Trametes versicolor at variable pH and protein oxidation state

    DEFF Research Database (Denmark)

    Christensen, Niels Johan; Kepp, Kasper Planeta

    2014-01-01

    Laccases are multi-copper oxidases having exquisite oxidation power, high stability, and multiple industrial applications. Although Km varies ?1000-fold across laccases, the molecular basis of substrate binding is poorly understood. Furthermore, laccase isoenzymes vary substantially in stability and activity for unknown reasons, and are thus useful probes of stability-function trade-offs relevant to protein engineering. We report here the first systematic comparison of ABTS-binding to different proteins, i.e. the four isoforms of Trametes versicolor, using a combination of sequence clustering, density functional theory calculations, homology modeling, and multiple induced-fit docking protocols at variable pH-dependent protonation states and T1-copper oxidation state. Clustering analysis provided a systematic overview of laccases across Trametes and revealed distinct isoenzyme classes (A–J) with the four T. versicolor isoforms belonging to separate classes. The T1 oxidation state had minor effect on ABTS binding, whereas the protonation state of Asp206 was important, consistent with site-directed mutagenesis studies. The absence of active poses for the ?-isoform agrees with its large Km, whereas the ?-isoform with the smallest Km also had most active poses with protonated Asp206 corresponding to its pHopt?2. Protonated Asp can bind to ABTS to form strong, active conformations partially explaining the low pHopt of fungal laccases toward ABTS. We identified several laccase properties optimal for ABTS binding. Notably, very high (R2?0.99) correlation was observed between logKm (ABTS) and binding-pocket charge due to sites 157, 161, 269, 271, and 333, i.e. laccases optimal for ABTS turnover have positively charged anchor points in their pockets. Our work also demonstrates how activity-constraints can markedly improve docking to reduce inactive false positives.

  11. The Thrombospondin-1 Mimetic ABT-510 Increases the Uptake and Effectiveness of Cisplatin and Paclitaxel in a Mouse Model of Epithelial Ovarian Cancer

    Directory of Open Access Journals (Sweden)

    Nicole E. Campbell

    2010-03-01

    Full Text Available Epithelial ovarian cancer (EOC comprises approximately 90% of ovarian cancers and arises from the surface epithelium. Typical treatment of EOC involves cytoreductive surgery combined with chemotherapy. More recent therapies have targeted the tumor vasculature using antiangiogenic compounds such as thrombospondin-1 (TSP-1. TSP-1 mimetic peptides such as ABT-510 have been created and have been in various clinical trials. We have previously shown that ABT-510 reduces abnormal vasculature associated with tumor tissue and increases the presence of mature blood vessels. It has been hypothesized that treatment with antiangiogenic compounds would allow increased delivery of cytotoxic agents and enhance treatment. In this study, we evaluated the potential role of ABT-510 and various chemotherapeutics (cisplatin and paclitaxel on tumor progression, angiogenesis, and the benefits of combinational treatments on tissue uptake and perfusion using an orthotopic syngeneic mouse model of EOC. Animals were treated with ABT-510 (100 mg/kg per day alone or in combination with cisplatin (2 mg/kg per 3 days or paclitaxel (10 mg/kg per 2 days at 60 days after tumor induction. Radiolabeled and fluorescently labeled paclitaxel demonstrated a significant increase in tumor uptake after ABT-510 treatment. Combined treatment with ABT-510 and cisplatin or paclitaxel resulted in a significant increase in tumor cell and tumor endothelial cell apoptosis and a resultant decrease in ovarian tumor size. Combined treatment also regressed secondary lesions and eliminated the presence of abdominal ascites. The results from this study show that through vessel normalization, ABT-510 increases uptake of chemotherapy drugs and can induce regression of advanced ovarian cancer.

  12. Free radical scavenging activity of papaya juice

    International Nuclear Information System (INIS)

    Papaya juice is an efficient scavenger of highly reactive hydroxyl radicals (OH radical) formed during 60Co irradiation of water. The OH anion radicals were detected by the electron spin resonance (ESR) technique of spin trapping using DMPO (5,5-dimethyl-1-pyrroline-N-oxide) or by a colorimetric assay in which salicylate is converted into polyhydroxybenzoic acids. Papaya juice is also able to quench the ESR signal of a stable free radical (TEMPOL) and the ESR signal of the DMPO-OH adduct. The active substance(s) in papaya juice are heat-stable, dialyzable, and soluble in water but not in lipid solvents. The active agents do not appear to be ascorbate, tocopherol, or carotenoids. (author)

  13. Oxygen derived free radicals and synovial fluid hyaluronate.

    OpenAIRE

    Saari, H

    1991-01-01

    High performance liquid chromatography with TSK 5000 PW or TSK 6000 PW size exclusion columns combined with a 125I labelled hyaluronic acid binding protein assay was used to study the effects of oxygen derived free radicals on synovial fluid hyaluronate. A continuous flux of free radicals was generated by the xanthine oxidase/hypoxanthine system. When the free radical flux was generated with xanthine oxidase/hypoxanthine in the presence of the iron chelator desferrioxamine and the hydroxyl ra...

  14. Free-Radical Polymer Science Structural Cancer Model: A Review

    OpenAIRE

    Richard C. Petersen

    2013-01-01

    Polymer free-radical lipid alkene chain-growth biological models particularly for hypoxic cellular mitochondrial metabolic waste can be used to better understand abnormal cancer cell morphology and invasive metastasis. Without oxygen as the final electron acceptor for mitochondrial energy synthesis, protons cannot combine to form water and instead mitochondria produce free radicals and acid during hypoxia. Nonuniform bond-length shrinkage of membranes related to erratic free-radical covalent ...

  15. Oxidation of SO2 by stabilized Criegee intermediate (sCI radicals as a crucial source for atmospheric sulfuric acid concentrations

    Directory of Open Access Journals (Sweden)

    M. Boy

    2013-04-01

    Full Text Available The effect of increased reaction rates of stabilized Criegee intermediates (sCIs with SO2 to produce sulfuric acid is investigated using data from two different locations, SMEAR II, Hyytiälä, Finland, and Hohenpeissenberg, Germany. Results from MALTE, a zero-dimensional model, show that using previous values for the rate coefficients of sCI + SO2, the model underestimates gas phase H2SO4 by up to a factor of two when compared to measurements. Using the rate coefficients recently calculated by Mauldin et al. (2012 increases sulfuric acid by 30–40%. Increasing the rate coefficient for formaldehyde oxide (CH2OO with SO2 according to the values recommended by Welz et al. (2012 increases the H2SO4 yield by 3–6%. Taken together, these increases lead to the conclusion that, depending on their concentrations, the reaction of stabilized Criegee intermediates with SO2 could contribute as much as 33–46% to atmospheric sulfuric acid gas phase concentrations at ground level. Using the SMEAR II data, results from SOSA, a one-dimensional model, show that the contribution from sCI reactions to sulfuric acid production is most important in the canopy, where the concentrations of organic compounds are the highest, but can have significant effects on sulfuric acid concentrations up to 100 m. The recent findings that the reaction of sCI + SO2 is much faster than previously thought together with these results show that the inclusion of this new oxidation mechanism could be crucial in regional as well as global models.

  16. Radical cyclization of ?-bromo aluminum acetals onto alkenes and alkynes (radic[Al] process): a simple access to ?-lactols and 4-methylene-?-lactols.

    Science.gov (United States)

    Boussonnière, Anne; Bénéteau, Romain; Zimmermann, Nicolas; Lebreton, Jacques; Dénès, Fabrice

    2011-05-01

    An efficient preparation of ?-lactols and methylene-?-lactols is described. Highly acid-sensitive lactols are prepared in a concise manner by using a radical cyclization of aluminum acetals. The precursors for the radical reactions are readily prepared from allyl or propargyl alcohols and ?-bromo acids. Functionalization of the resulting ?-lactols and methylene-?-lactols can be achieved following isolation, leading to synthetically useful building blocks, such as 1,4-diols, 1,4-dienes, ?-lactones, and polysubstituted tetrahydrofurans. PMID:21472805

  17. Hydroxyl radical production by H2O2-mediated oxidation of Fe(II) complexed by Suwannee River fulvic acid under circumneutral freshwater conditions.

    Science.gov (United States)

    Miller, Christopher J; Rose, Andrew L; Waite, T David

    2013-01-15

    The Fenton reaction, the oxidation of ferrous iron by hydrogen peroxide (H(2)O(2)), is typically assumed to be a source of hydroxyl radical (HO(•)) in natural systems, however, formation of HO(•) in this process is strongly dependent upon solution pH and the ligand environment, with HO(•) only formed when Fe(II) is organically complexed. In this study we examine the formation of HO(•) when Fe(II)-NOM complexes are oxidized by H(2)O(2) using phthalhydrazide as a probe for HO(•). We demonstrate that HO(•) formation can be quantitatively described using a kinetic model that assumes HO(•) formation occurs solely from the reaction of Fe(II)-NOM complexes with H(2)O(2), even though this reaction is sufficiently slow to play only a negligible role in the overall oxidation rate of total Fe(II). As such, NOM is seen to play a dual role in circumneutral natural systems in stabilizing Fe(II) toward oxidation by H(2)O(2) while enabling the formation of HO(•) through this oxidation process. PMID:23231429

  18. Study of the manganese (II) manganese (III) complexes with quinaldic acid in aprotic medium, mononuclear and binuclear species produced under these conditions and possible formation of radical species upon oxidation or reduction of the ligand

    Energy Technology Data Exchange (ETDEWEB)

    Bodini, E.M.; Funes, M.M.; Valle, M.A. del; Arancibia, V. [Departamento de Quimica Analitica y Electroquimica, Facultad de Quimica, Universidad Catolica de Chile (Switzerland)

    1996-11-01

    The redox chemistry of the ligand Quinaldic acid (2-QA), its monoanion and its complexes with manganese (II) and manganese (III) has studied in dimethylsulphoxide using electrochemical, spectroscopic and magnetic measurements. The protonated ligand is reduce at -1.28 V vs SCE with the transfer of one equivalent of charge the resulting solution presents oxidation peaks at -0.02 V, +0.32 V and +1.14 V vs SCE which is indicative that both radical and dimeric species are involved in the oxidation processes. The combination of the monoanion of the ligand with Mn(II) in a 1:2 mole ratio forms a stable complex which presents a magnetic susceptibility of 5.90B.M. and conditional formation constant of 1.71 x 10``8 M``-2. Its oxidation at +0.76 V vs SCE yields a brown complex of Mn(III) with a magnetic susceptibility of 4.80 B.M. The voltammetric behaviour of the latter species indicates that is probably binuclear. This complex is reduced at +0.60 V vs SCE generating a Mn(II)-Mn(III) mixed-valance complex, and a second reduction at -0.40 V vs SCE regenerating the mononuclear Mn(II) complex. The mixed-valance complex decomposes quickly generating the corresponding Mn(II) and Mn(III) monomers. On the other hand, in the presence of this metal ion as counter-ion, both its +2 or +3 oxidation state, the monoanion of the ligand shows reduction processes that might lead to the stabilization of radical species. the voltammetric and spectroscopic characterization if these species is described. The results may be useful to the understanding of the charge transfer mechanism in biological systems. (Author) 26 refs.

  19. Effect of free radical spin trap N-tert-butyl-alpha-phenylnitrone (PBN) on seizures induced in immature rats by homocysteic acid.

    Czech Academy of Sciences Publication Activity Database

    Folbergrová, Jaroslava; Druga, Rastislav; Otáhal, Jakub; Haugvicová, Renata; Mareš, Pavel; Kubová, Hana

    2006-01-01

    Ro?. 201, ?. 1 (2006), s. 105-119. ISSN 0014-4886 R&D Projects: GA ?R(CZ) GA309/05/2015; GA ?R(CZ) GA309/02/1238 Institutional research plan: CEZ:AV0Z50110509; CEZ:AV0Z50200510 Keywords : DL-homocysteic acid induced seizures * neuronal damage * protection Subject RIV: ED - Physiology Impact factor: 4.156, year: 2006

  20. Radiolysis study of the alloxan-dialuric acid couple. I. The reduction of alloxan by e/sub aq/- and COO- radicals

    International Nuclear Information System (INIS)

    Reduction of alloxan (A) to dialuric acid (AH2) by e/sub aq/- and COO- has been studied by ? and pulse radiolysis. By ? radiolysis, the G-value for dialuric acid formation is equal to G(AH2) = 4.7 +- 0.25 eq/100 eV = G/sub H/ + G/sub e//sub aq/- +G/sub OH/ - 2G/sub H2O/, dialuric acid being oxidized by H2O2. Pulse radiolysis gives evidence for an intermediate AH formation which should be of a semiquinone type, and whose absorption spectrum has been characterized. Its production rate constants by reactions of e/sub aq/- and COO- with alloxan were measured: k(e/sub aq/- + A) = (1.7 +- 0.02) x 1010 M-1 sec-1; k(COO- + A) = (3.7 +- 1.1) x 107 M-1 sec-1. AH disappears by disproportionation with a rate constant 2k = (1.6 +- 0.03) x 108 M-1 sec-1

  1. Radiolysis study of the alloxan-dialuric acid couple. I. The reduction of alloxan by e/sub aq//sup -/ and COO/sup -/ radicals

    Energy Technology Data Exchange (ETDEWEB)

    Houee-Levin, C.; Gardes-Albert, M.; Ferradini, C.; Pucheault, J.

    1980-08-01

    Reduction of alloxan (A) to dialuric acid (AH/sub 2/) by e/sub aq//sup -/ and COO/sup -/ has been studied by ..gamma.. and pulse radiolysis. By ..gamma.. radiolysis, the G-value for dialuric acid formation is equal to G(AH/sub 2/) = 4.7 +- 0.25 eq/100 eV = G/sub H/ + G/sub e//sub aq//sup -/ +G/sub OH/ - 2G/sub H/sub 2/O/, dialuric acid being oxidized by H/sub 2/O/sub 2/. Pulse radiolysis gives evidence for an intermediate AH formation which should be of a semiquinone type, and whose absorption spectrum has been characterized. Its production rate constants by reactions of e/sub aq//sup -/ and COO/sup -/ with alloxan were measured: k(e/sub aq//sup -/ + A) = (1.7 +- 0.02) x 10/sup 10/ M/sup -1/ sec/sup -1/; k(COO/sup -/ + A) = (3.7 +- 1.1) x 10/sup 7/ M/sup -1/ sec/sup -1/. AH disappears by disproportionation with a rate constant 2k = (1.6 +- 0.03) x 10/sup 8/ M/sup -1/ sec/sup -1/.

  2. Aliphatic peptidyl hydroperoxides as a source of secondary oxidation in hydroxyl radical protein footprinting

    OpenAIRE

    Saladino, Jessica; Liu, Mian; Live, David; Sharp, Joshua S.

    2009-01-01

    Hydroxyl radical footprinting is a technique for studying protein structure and binding that entails oxidizing a protein system of interest with diffusing hydroxyl radicals, and then measuring the amount of oxidation of each amino acid. One important issue in hydroxyl radical footprinting is limiting amino acid oxidation by secondary oxidants to prevent uncontrolled oxidation which can cause amino acids to appear more solvent accessible than they really are. Previous work suggested that hydro...

  3. Cistectomía radical robótica / Robotic radical cystectomy

    Scientific Electronic Library Online (English)

    Burak, Turna; Monish, Aron; Georges-Pascal, Haber; Inderbir S., Gill; Jihad H., Kaouk.

    2007-05-01

    Full Text Available Objetivos: En la última década hemos visto un tremendo crecimiento en la implantacion y desarrollo de los robots quirúrgicos. Popularizados por la prostatectomía radical, las técnicas robóticas están siendo, en la actualidad, muy aplicadas en la cistectomía radical. Trataremos aquí de revisar el des [...] arrollo y estado actual de la cistectomía radical robótica (CRR) en la práctica contemporánea de la urología. Métodos: Se ha revisado toda la literatura publicada, entre 1995 y 2007, en la base de datos de la Biblioteca Nacional de Medicina (MEDLINE) utilizando las palabras clave: robótica, asistido por robot, laparoscópica y cistectomía. Desde el primer trabajo en 2003, se han encontrado 9 originales publicados. Se valoraron con respecto a la técnica, ventajas y desventajas perioperatorias y resultados oncológicos. Describimos asimismo nuestra experiencia inicial, aún no publicada. Resultados: En este momento todos los artículos publicados sobre la CRR se basan en un número pequeño de pacientes con seguimientos a corto plazo. No obstante, demuestran la viabilidad de la CRR con resultados perioperatorios esperanzadores. Comparada con la cistectomía radical abierta (CRA), la CRR parece estar asociada con menor pérdida de sangre, estancia hospitalaria y necesidades analgésicas. Estas ventajas se encuentran asimismo en la cistectomía radical laparoscópica (CRL) y son una función del abordaje mínimamente invasivo. El tiempo quirúrgico es mayor, de forma considerable cuando el tiempo intestinal se realiza de manera intracorpórea. Conclusiones: La cistectomía radical robótica está en evolución. La viabilidad técnica ha sido demostrada. Los resultados perioperatorios iniciales son prometedores. Los resultados oncológicos esperan identificar el papel de la misma en el manejo del cáncer de vejiga. Se necesitan ensayos prospectivos y aleatorizados comparando la CRA con la CRR y la CRL. Abstract in english Objectives: The last decade has seen tremendous growth of surgical robotics. Popularized for radical prostatectomy, robotic techniques are now increasingly being applied to radical cystectomy. Herein, we review the development and current status of robotic radical cystectomy (RRC) in contemporary ur [...] ological practice. Methods: Between 1995 and 2007 published literature was reviewed using the National Library of Medicine database and the following key words: robotic, robot-assisted, laparoscopic and cystectomy. Since the first report in 2003, nine published original reports were identified. These were evaluated with regards to the technique, advantages and disadvantages, perioperative and oncological outcomes. Our initial experience, as yet unpublished, is also described. Results: At this writing, all published papers on RRC are based on small number of patients with short-term follow-up. Nevertheless, they have demonstrated the technical feasibility of RRC with encouraging perioperative outcomes. Compared to open radical cystectomy (ORC), RRC appears to be associated with decreased blood loss, hospital stay and analgesic requirement. These advantages are also found with laparoscopic radical cystectomy (LRC) and are a function of the minimally invasive approach. The operating time is longer, markedly so when the bowel work is performed intracorporeally. Conclusions: RRC is in evolution. Technical feasibility has been demonstrated. Initial perioperative outcomes are encouraging. Oncological outcomes are awaited to identify the role of RRC in the management of bladder cancer. Multi-center prospective randomized trials comparing ORC with RRC and LRC are necessary.

  4. Bcl2L12 with a BH3-like domain in regulating apoptosis and TMZ-induced autophagy: a prospective combination of ABT-737 and TMZ for treating glioma.

    Science.gov (United States)

    Yang, Ming-Chang; Loh, Joon-Khim; Li, Yi-Yang; Huang, Wen-Sheng; Chou, Chia-Hua; Cheng, Jiin-Tsuey; Wang, Yeng-Tseng; Lieu, Ann-Shung; Howng, Shen-Long; Hong, Yi-Ren; Chou, An-Kuo

    2015-03-01

    Bcl2L12 as a new member of the Bcl2 family, which contains a BH2 domain and shares a lower amino acid similarity with other Bcl2 family proteins. Bcl2L12 is reported to be involved in apoptosis regulation, but this role remains controversial in different cancer type. Temozolomide (TMZ) is currently used to intervene glioma multiforme (GBM), but an acquired chemotherapeutic resistance maybe occurred due to undesired autophagy. Previous studies uncovered that Bcl2L12 may interact with Bcl-xL and may harbor a BH3-like domain. Therefore, we investigated whether this BH3-like domain is responsible for the Bcl2L12 anti-apoptotic property. Moreover, we tested whether ABT-737, a BH3 mimetic agent, can be combined with TMZ to treat GBM. We aligned Bcl2L12 with Bcl2 family members, compared interacting pattern of BH3 domain and their protein 3D structure. We identified that Bcl2L12 interacts with Bcl-xL and Bcl2 in yeast two-hybrid system. Bcl2L12192-220 was a minimal region for Bcl2L12-Bcl-xL interaction. Five-point mutations with respect to hydrophobic and charge residues were generated to test whether they are the key residue of BH3-like domain. Our data showed that both h1 (L213) and h2 residue (L217) are essential for Bcl2L12 interacting with Bcl2 family proteins. Ectopically expressed h1 or h2 mutant in U87MG cell line resulted in reactivation of cleaved-PARP, caspase-3 and cytochrome c releasing compared to Bcl2L12 wt group. Implementing ABT-737 combined with TMZ provided a superior effect on apoptosis induction in Bcl2L12 wt group, which effectively reactivated apoptotic markers. Altogether, our findings indicated that Bcl2L12 retains a BH3-like domain, which is important for the Bcl2L12 anti-apoptotic property and TMZ-induced autophagy. Our results basically support the idea of using ABT-737 to counteract the anti-apoptotic role of Bcl2L12 and sensitize drug response of the GBM cells to TMZ. PMID:25586056

  5. Radical transfer between proteins: role of tyrosine, tryptophan and protein peroxyl radicals

    International Nuclear Information System (INIS)

    Reaction of the Fe(III) forms of the heme proteins myoglobin (Mb) and horseradish peroxidase (HRP) with H2O2 gives rise to high-oxidation-state heme-derived species which can be described as a Fe(IV)-oxo porphyrin radical-cation ('Compound 1'). In the case of Mb, the Fe(IV)-oxo porphyrin radical-cation undergoes rapid electron transfer with the surrounding protein to give protein (globin)-derived radicals and an Fe(lV)-oxo species ('Compound 2'). The globin-derived radicals have been shown to be located at two (or more) sites: Tyr-103 or Trp-14, with the latter radical known to react with oxygen to give a Trp-derived peroxyl radical (Mb-Trp-OO*). With HRP, the Fe(lV)-oxo porphyrin radical-cation carries out two successive one-electron oxidation reactions at the exposed heme edge to give firstly 'Compound 2' [the Fe(lV)oxo species] and then the resting Fe(III) state of the enzyme. n this study we have investigated whether the Trp-14 peroxyl radical from Mb and the Compound 1 and 2 species from HRP (in the absence and presence of free Tyr) can oxidise amino acids, peptides and proteins. Such reactions constitute intermolecular protein-to-protein radical transfer reactions and hence protein chain-oxidation. We have also examined whether these oxidants react with antioxidants. Reaction of these heme-protein derived oxidants with amino acids, proteins and antioxidants has been carried out at room temperature for defined periods of time before freeze-qor defined periods of time before freeze-quenching to 77K to halt reaction. The radical species present in the reaction system at the time of freezing were subsequently examined by EPR spectroscopy at 77K. Three free amino acids, Tyr, Trp and Cys (with Cys the least efficient) have been shown to react rapidly with Mb-Trp-OO*, as evidenced by the loss of the characteristic EPR features of Mb-Trp-OO* on inclusion of increasing concentrations of the amino acids. All other amino acids are much less reactive. Evidence has also been obtained for (inefficient) hydrogen atom abstraction from ?-carbon sites on peptides; this may give rise to backbone cleavage in the presence of oxygen

  6. Generation and characterization of ABT-981, a dual variable domain immunoglobulin (DVD-Ig(TM)) molecule that specifically and potently neutralizes both IL-1? and IL-1?.

    Science.gov (United States)

    Lacy, Susan E; Wu, Chengbin; Ambrosi, Dominic J; Hsieh, Chung-Ming; Bose, Sahana; Miller, Renee; Conlon, Donna M; Tarcsa, Edit; Chari, Ravi; Ghayur, Tariq; Kamath, Rajesh V

    2015-05-01

    Interleukin-1 (IL-1) cytokines such as IL-1?, IL-1?, and IL-1Ra contribute to immune regulation and inflammatory processes by exerting a wide range of cellular responses, including expression of cytokines and chemokines, matrix metalloproteinases, and nitric oxide synthetase. IL-1? and IL-1? bind to IL-1R1 complexed to the IL-1 receptor accessory protein and induce similar physiological effects. Preclinical and clinical studies provide significant evidence for the role of IL-1 in the pathogenesis of osteoarthritis (OA), including cartilage degradation, bone sclerosis, and synovial proliferation. Here, we describe the generation and characterization of ABT-981, a dual variable domain immunoglobulin (DVD-Ig) of the IgG1/k subtype that specifically and potently neutralizes IL-1? and IL-1?. In ABT-981, the IL-1? variable domain resides in the outer domain of the DVD-Ig, whereas the IL-1? variable domain is located in the inner position. ABT-981 specifically binds to IL-1? and IL-1?, and is physically capable of binding 2 human IL-1? and 2 human IL-1? molecules simultaneously. Single-dose intravenous and subcutaneous pharmacokinetics studies indicate that ABT-981 has a half-life of 8.0 to 10.4 d in cynomolgus monkey and 10.0 to 20.3 d in rodents. ABT-981 exhibits suitable drug-like-properties including affinity, potency, specificity, half-life, and stability for evaluation in human clinical trials. ABT-981 offers an exciting new approach for the treatment of OA, potentially addressing both disease modification and symptom relief as a disease-modifying OA drug. PMID:25764208

  7. Composition of Essential Oil, Radical Scavenging and Antibacterial Properties of Interspecific Hybrid Thymus × oblongifolius Opiz

    Directory of Open Access Journals (Sweden)

    Kristina Lo žien?

    2012-01-01

    Full Text Available Radical scavenging and antibacterial properties of thyme extracts isolated from the two different Thymus × oblongifolius Opiz samples (TO1 and TO2 were studied. The oil of the TO1 was constituted mainly of hydrocarbon terpenes (83.4%, while the oil of the TO2 was composed mainly of oxygenated compounds with a -terpenyl acetate (37.9% being the major one. The extracts isolated with hexane, acetone and ethanol from the whole and deodorized herb were tested for their radical scavenging capacity (RSC in the model reaction systems containing stable radical DPPH • and cation radical ABTS •+. The extracts isolated with ethanol from undeodorized herb possessed the strongest RSC, while hexane extracts were not active. Undeodorized acetone extracts of the TO1 possessed higher RSC than those of the TO2, while undeodorized ethanol extracts of the TO2 were stronger radical scavengers than similar extracts of the TO1. The antibacterial activity of the extracts tested by using seven food pathogenic species depended on the species, extract concentration and extract type. Bacillus cereus, Staphylococcus aureus and St. epidermidis were more sensitive to plant extracts than Micrococcus luteus, Esherichia coli, Salmonella typhimurium and Enterobacter aerogenes.

  8. Oxygen radicals stimulate guinea pig gallbladder glycoprotein secretion in vitro

    International Nuclear Information System (INIS)

    In several animal models of cholelithiasis, and in humans with gallstones, hypersecretion of gallbladder mucin is observed. This study was undertaken to determine the effect of oxygen radicals on guinea pig gallbladder glycoprotein secretion in organ culture. Mucosal explants were incubated with [3H]glucosamine hydrochloride to label glycoproteins, then exposed to oxygen radicals generated by chelated ferric iron and ascorbic acid. Marked stimulation of glycoprotein release was observed after a 30-min exposure to the oxygen radical-generating system, and the effect was inhibited by mannitol. The stimulatory effect of hydroxyl radical was not accompanied by leakage of intracellular lactate dehydrogenase. Parallel experiments with human granulocytes activated with f-Met-Leu-Phe and coincubated with gallbladder explants revealed similar results. These results indicate that oxygen radicals, especially the hydroxyl radical (OH), are capable of stimulating rapid release of mucous-type glycoproteins from gallbladder epithelium

  9. Fenoles totales y capacidad antioxidante estimada con los ensayos DPPH/ABTS en rosas en soluciones preservantes / Total phenols and antioxidant capacity estimated with DPPH/ABTS assays in roses on preservative solutions

    Scientific Electronic Library Online (English)

    Nadia, Zenil Lugo; Ma. Teresa, Colinas León; Cecilio, Bautista Bañuelos; Tito Roque, Vázquez Rojas; Héctor, Lozoya Saldaña; Ma.Teresa, Martínez Damián.

    1029-10-01

    Full Text Available Tallos de rosa 'Freedom' se evaluaron en dos soluciones preservantes: 8-citrato de hidroxiquinoleina (HQC) y Chrysal CLEAR Professional 2® T-bag (CHRYSAL) en un pulso de 24 h a temperatura ambiente (24 ± 2 °C, 75 % HR) y agua como testigo. Se utilizó un diseño completamente al azar con cuatro repeti [...] ciones, la unidad experimental fue un tallo floral. Se evaluó la vida de florero, el contenido de fenoles totales con el método colorimétrico de Folin-Ciocalteauy la capacidad antioxidante total (caT) con los ensayos DPPH y ABTS tanto en hoja como en pétalo. Se realizó el ANOVA y correlaciones simples entre la caT y el contenido de fenoles, y entre ambos ensayos. Los resultados muestran que las soluciones preservantes promueven un aumento en la caT y contenido de fenoles totales en hoja, pero no en pétalo. Las hojas de los tallos florales tratados con CHRYSAL presentaron los mayores contenidos de fenoles totales y caT, mientras que el testigo los menores. La vida media de florero fue de: 13, 11 y 9 días para los tratados con CHRYSAL, HQC y el testigo, respectivamente. El contenido de fenoles totales presentó una estrecha relación positiva (?? 0.01) con la caT: 0.87 y 0.85 medida con el ABTS y 0.92 y 0.85 con el DPPH en hoja y pétalo respectivamente y también ambos métodos se correlacionaron entre sí positiva y significativamente (r= 0.91) en hoja y (r= 0.93) en pétalo. Abstract in english Rose stems 'Freedom' were evaluated in two preservative solutions: 8-hydroxyquinoline citrate (HQC) and Chrysal CLEAR® Professional 2 T-bag (CHRYSAL) in a pulse of 24 h at room temperature (24 ± 2 °C, 75% HR) and water as control. A completely randomized design with four replications was used; the e [...] xperimental unit was a flower stem. Vase life, total phenolic content with the colorimetric method Folin-Ciocalteauy, total antioxidant capacity (caT) with DPPH and ABTS assays in both leaf and petal was evaluated. ANOVA and simple correlations between caT and content of phenols and between both assays was made. The results show that preservative solutions promote an increase in caT and total phenolic content in leaf, but not in petal. The leaves of the flowering stems treated with CHRYSAL had the highest contents of total phenols and caT, while control the lowest. The average vase life was 13, 11 and 9 days for those treated with CHRYSAL, HQC and control, respectively. The total phenolic content showed a strong positive relation (? ?0.01) with caT: 0.87 and 0.85 measured with ABTS and 0.92 and 0.85 with DPPH in leaf and petal respectively and also both methods were correlated positively and significantly with each other (r= 0.91) in leaf and (r= 0.93) in petal.

  10. Prostatectomia radical laparoscópica / Radical laparoscopic prostatectomy

    Scientific Electronic Library Online (English)

    OCTAVIO A, CASTILLO C; IVAR, VIDAL-MORA; RAFAEL, SÁNCHEZ-SALAS.

    2011-04-01

    Full Text Available La Prostatectomia radical laparoscópica (PRL) se ha convertido en una técnica atractiva para el tratamiento quirúrgico del cáncer de próstata localizado. Si bien, los resultados actuales son inicialmente comparables a la prostatectomia radical abierta, es importante mencionar que la tendencia quirúr [...] gica en cáncer de próstata, se ha modificado a pesar de que no hay estudios que confirmen la superioridad del método endoscópico y hoy, el estándar dorado sigue siendo la prostatectomia radical abierta. Dos rutas de acceso quirúrgico pueden ser utilizadas para la realización de PRL, la vía extraperitoneal y la transperitoneal. Un menor sangrado y menor tasa de transfusión, así como, tiempo de hospitalización y recuperación más cortos, son ventajas incuestionables para los procedimientos laparoscópicos. Los resultados oncológicos y funcionales de la prostatectomia laparoscópica son hoy en día comparables, pero en ningún caso mejores que la técnica retropúbica abierta estándar. Recientemente, Hu y colaboradores, en base a una revisión de cerca de 3.000 pacientes tratados en los Estados Unidos, plantean la posibilidad de que los pacientes tratados con prostatectomia laparoscópica (pura o asistida por robot), pudiesen tener mayor riesgo de recurrencia de la enfermedad. Esta es una posición discutible, ya que el análisis, a pesar de ser extenso es limitado para establecer conclusiones finales en el tema. Es importante recordar que la PRL sigue siendo una intervención técnicamente difícil y debiera ser realizada en centros seleccionados con equipos experimentados. La prostatectomía laparoscópica asistida por Robot, facilita el procedimiento y en suma, pareciera mejorar los resultados oncológicos y funcionales. La PRL es hoy en día una alternativa válida a la prostatectomía retropúbica tradicional, con ciertas ventajas adicionales. Abstract in english Radical laparosocpic prostatectomy (RLP) is an attractive therapeutic modality for localized prostate cancer. The results obtained with this technique are similar to those obtained with open radical prostatectomy, which continues to be the gold standard for the treatment of prostate cancer. The surg [...] ical access for RLP can be extra-peritoneal or trans-peritoneal. The advantages of laparoscopy are lower bleeding rates, less need for transfusion and shorter recuperation time and hospital stay. The oncological results of RLP are similar, but in any case better, that those obtained with open retropubic radical prostatectomy. Recent reports raised the concern that laparoscopic prostatectomy could have higher rates of relapse of cancer. However this opinion is questionable. RLP is a difficult technique and should be performed by experienced teams. Robot assistance facilitates the procedure and could improve functional and oncological results. Therefore RLP is nowadays an alternative to traditional retropubic prostatectomy.

  11. Prostatectomia radical laparoscópica Radical laparoscopic prostatectomy

    Directory of Open Access Journals (Sweden)

    OCTAVIO A CASTILLO C

    2011-04-01

    Full Text Available La Prostatectomia radical laparosc?pica (PRL se ha convertido en una técnica atractiva para el tratamiento quirúrgico del cáncer de próstata localizado. Si bien, los resultados actuales son inicialmente comparables a la prostatectomia radical abierta, es importante mencionar que la tendencia quirúrgica en cáncer de próstata, se ha modificado a pesar de que no hay estudios que confirmen la superioridad del método endoscópico y hoy, el estándar dorado sigue siendo la prostatectomia radical abierta. Dos rutas de acceso quirúrgico pueden ser utilizadas para la realización de PRL, la vía extraperitoneal y la transperitoneal. Un menor sangrado y menor tasa de transfusión, así como, tiempo de hospitalización y recuperación más cortos, son ventajas incuestionables para los procedimientos laparoscópicos. Los resultados oncológicos y funcionales de la prostatectomia laparoscópica son hoy en día comparables, pero en ningún caso mejores que la técnica retropúbica abierta estándar. Recientemente, Hu y colaboradores, en base a una revisión de cerca de 3.000 pacientes tratados en los Estados Unidos, plantean la posibilidad de que los pacientes tratados con prostatectomia laparoscópica (pura o asistida por robot, pudiesen tener mayor riesgo de recurrencia de la enfermedad. Esta es una posición discutible, ya que el análisis, a pesar de ser extenso es limitado para establecer conclusiones finales en el tema. Es importante recordar que la PRL sigue siendo una intervención técnicamente difícil y debiera ser realizada en centros seleccionados con equipos experimentados. La prostatectomía laparoscópica asistida por Robot, facilita el procedimiento y en suma, pareciera mejorar los resultados oncológicos y funcionales. La PRL es hoy en día una alternativa válida a la prostatectomía retropúbica tradicional, con ciertas ventajas adicionales.Radical laparosocpic prostatectomy (RLP is an attractive therapeutic modality for localized prostate cancer. The results obtained with this technique are similar to those obtained with open radical prostatectomy, which continues to be the gold standard for the treatment of prostate cancer. The surgical access for RLP can be extra-peritoneal or trans-peritoneal. The advantages of laparoscopy are lower bleeding rates, less need for transfusion and shorter recuperation time and hospital stay. The oncological results of RLP are similar, but in any case better, that those obtained with open retropubic radical prostatectomy. Recent reports raised the concern that laparoscopic prostatectomy could have higher rates of relapse of cancer. However this opinion is questionable. RLP is a difficult technique and should be performed by experienced teams. Robot assistance facilitates the procedure and could improve functional and oncological results. Therefore RLP is nowadays an alternative to traditional retropubic prostatectomy.

  12. Radical chemistry of artemisinin

    International Nuclear Information System (INIS)

    The review summarizes physicochemical characteristics of the natural sesquiterpene peroxide artemisinin. The kinetic schemes of transformations of artemisinin radicals under anaerobic conditions are presented and analyzed. The sequence of radical reactions of artemisinin in the presence of oxygen is considered in detail. Special emphasis is given to the intramolecular chain oxidation resulting in the transformation of artemisinin into polyatomic hydroperoxide. The kinetic characteristics of elementary reaction steps involving alkyl, alkoxyl, and peroxyl radicals generated from artemisinin are discussed. The results of testing of artemisinin and its derivatives for the antimalarial activity and the scheme of the biochemical synthesis of artemisinin in nature are considered.

  13. Radical chemistry of artemisinin

    Science.gov (United States)

    Denisov, Evgenii T.; Solodova, S. L.; Denisova, Taisa G.

    2010-12-01

    The review summarizes physicochemical characteristics of the natural sesquiterpene peroxide artemisinin. The kinetic schemes of transformations of artemisinin radicals under anaerobic conditions are presented and analyzed. The sequence of radical reactions of artemisinin in the presence of oxygen is considered in detail. Special emphasis is given to the intramolecular chain oxidation resulting in the transformation of artemisinin into polyatomic hydroperoxide. The kinetic characteristics of elementary reaction steps involving alkyl, alkoxyl, and peroxyl radicals generated from artemisinin are discussed. The results of testing of artemisinin and its derivatives for the antimalarial activity and the scheme of the biochemical synthesis of artemisinin in nature are considered.

  14. Poly (N-vinyl-2-pyrrolidone-co-acrylic acid): Comparing of Traditional Heating and Microwave-Assisted Free Radical Polymerization

    International Nuclear Information System (INIS)

    In organic chemistry microwave irradiation has become a common heat source and the use of microwave irradiation is also increasingly studied for polymerization reactions. Polymers have been synthesized at long reaction times by classical thermal methods. In contrast, microwave-assisted polymer synthesis is a well-known and most useful method, which is requiring shorter reaction times. In this study, our aims are to compare THPS and MAPS methods between themselves, and investigate the effect of temperature in MAPS method at different parameters such as reaction times, weight average molecular weight (Mw), polydispersity index (PDI), hydrodynamic radius (Rh), intrinsic and Mark Houwink equation constant (a) of copolymers, viscosity Firstly we synthesized N-vinyl-2-pyrrolidone-acrylic acid copolymers (P(VP-co-AA)) both with traditional heating polymer synthesis (THPS) and microwave-assisted polymer synthesis (MAPS) method comparatively in this study. Secondly, to research temperature effect on MAPS method in addition to microwave irradiation power, polymer synthesis at 40 degree C, 50 degree C and 80 degree C were tried. For analyzing of copolymers Fourier Transform Infrared (FT-IR) spectroscopy and Gel Permeation Chromatography (GPC) system with four detectors were used. (author)

  15. Polycarbonate radiolysis: radicals formation

    International Nuclear Information System (INIS)

    Polycarbonate (PC) Durolon, national, amorphous, is used in medical applications and may be sterilized by gamma radiation. The interaction of the radiation with Durolon produce scissions in main chain generating phenoxy and phenyl polymeric radicals observed by Electronic Spin Resonance (ESR). These radicals to become trapped in polymeric matrix absorbing photons in visible range; been, therefore, the cause of the degradation on polymer. It was investigated the influence of additives, presents in formulation, on decay of radicals. ESR spectra of simultaneous irradiated samples, in same conditions, in two environment: vacuum (10 -5 mmHg) and air, shown that the O2 (in air) not produce peroxy radicals in irradiated Durolon, at contrary of polypropylene. (author)

  16. Staining of wool using the reaction products of ABTS oxidation by laccase: synergetic effects of ultrasound and cyclic voltammetry.

    Science.gov (United States)

    Munteanu, Florentina-Daniela; Basto, Carlos; Gübitz, Georg M; Cavaco-Paulo, Artur

    2007-03-01

    The effects of ultrasound on 2,2'-Azinobis(3-ethylbenzothiazoline-6-sulfonate) enzymatic oxidation by laccase (Trametes villosa) has been studied by means of cyclic voltammetry. The reaction was allowed to proceed in the presence of a piece of wool and the coloration depth of the wool fabric was measured by means of K/S. It was observed that cyclic voltammetry is influenced the dyeing process and higher K/S values were obtained when the cyclic voltammetry was combined with the ultrasonic irradiation. Moreover, the K/S value is the sum of the values obtained when the wool staining is done in just the presence of cyclic voltammetry or in just the presence of ultrasound. The results obtained on the indigo carmine decolourization gives information on the importance of controlling the amount of ABTS(+) formed during the ultrasonication process. PMID:16979370

  17. Resveratrol products resulting by free radical attack

    Energy Technology Data Exchange (ETDEWEB)

    Bader, Yvonne; Quint, R.M. [Section Radiation Biology, Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Getoff, Nikola [Section Radiation Biology, Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, UZAII, Althanstrasse 14, A-1090 Vienna (Austria)], E-mail: nikola.getoff@univie.ac.at

    2008-06-15

    Trans-resveratrol (trans-3,4',5-trihydroxystilbene; RES), which is contained in red wine and many plants, is one of the most relevant and extensively investigated stilbenes with a broad spectrum of biological activities. Among other duties, RES has been reported to have anti-carcinogenetic activities, which could be attributed to its antioxidant properties. The degradation of RES was studied under various conditions. The products (aldehydes, carboxylic acids, etc.) generated from RES by the attack of free radicals were registered as a function of the radical concentration (absorbed radiation dose). Based on the obtained data it appears that the OH radicals are initiating the rather complicated process, which involves of the numerous consecutive reactions. A possible starting reaction mechanism is presented.

  18. Resveratrol products resulting by free radical attack

    International Nuclear Information System (INIS)

    Trans-resveratrol (trans-3,4',5-trihydroxystilbene; RES), which is contained in red wine and many plants, is one of the most relevant and extensively investigated stilbenes with a broad spectrum of biological activities. Among other duties, RES has been reported to have anti-carcinogenetic activities, which could be attributed to its antioxidant properties. The degradation of RES was studied under various conditions. The products (aldehydes, carboxylic acids, etc.) generated from RES by the attack of free radicals were registered as a function of the radical concentration (absorbed radiation dose). Based on the obtained data it appears that the OH radicals are initiating the rather complicated process, which involves of the numerous consecutive reactions. A possible starting reaction mechanism is presented

  19. Safety and Efficacy of ABT-089 in Pediatric Attention-Deficit/Hyperactivity Disorder: Results from Two Randomized Placebo-Controlled Clinical Trials

    Science.gov (United States)

    Wilens, Timothy E.; Gault, Laura M.; Childress, Ann; Kratochvil, Christopher J.; Bensman, Lindsey; Hall, Coleen M.; Olson, Evelyn; Robieson, Weining Z.; Garimella, Tushar S.; Abi-Saab, Walid M.; Apostol, George; Saltarelli, Mario D.

    2011-01-01

    Objective: To assess the safety and efficacy of ABT-089, a novel alpha[subscript 4]beta[subscript 2] neuronal nicotinic receptor partial agonist, vs. placebo in children with attention-deficit/hyperactivity disorder (ADHD). Method: Two multicenter, randomized, double-blind, placebo-controlled, parallel-group studies of children 6 through 12 years…

  20. Pomegranate seed oil: Effect on 3-nitropropionic acid-induced neurotoxicity in PC12 cells and elucidation of unsaturated fatty acids composition.

    Science.gov (United States)

    Al-Sabahi, Bushra N; Fatope, Majek O; Essa, Musthafa Mohamed; Subash, Selvaraju; Al-Busafi, Saleh N; Al-Kusaibi, Fatma S N; Manivasagam, Thamilarasan

    2014-09-19

    Background Seed oils are used as cosmetics or topical treatment for wounds, allergy, dandruff, and other purposes. Natural antioxidants from plants were recently reported to delay the onset or progress of various neurodegenerative conditions. Over one thousand cultivars of Punica granatum (Punicaceae) are known and some are traditionally used to treat various ailments. Aim The effect of pomegranate oil on 3-nitropropionic acid- (3-NP) induced cytotoxicity in rat pheochromocytoma (PC12) neuronal cells was analyzed in this study. Furthermore, the analysis of unsaturated fatty acid composition of the seed oil of pomegranate by gas chromatography-electron impact mass spectrometry (GC-MS) was done. Results GC-MS study showed the presence of 6,9-octadecadiynoic acid (C18:2(6,9)) as a major component (60%) as 4,4-dimethyloxazoline derivative. The total extractable oil with light petroleum ether by Soxhlet from the dry seed of P. granatum was 4-6%. The oil analyzed for 48.90 ±?1.50 mg gallic acid equivalents/g of oil, and demonstrated radical-scavenging-linked antioxidant activities in various in vitro assays like the DPPH (2,2-diphenyl-l-picrylhydrazyl, % IP = 35.2 ± 0.9%), ABTS (2,2'-azino-bis-3-ethylene benzothiozoline-6-sulfonic acid, % IP 2.2 ± 0.1%), and ?-carotene bleaching assay (% IP = 26 ± 3%), respectively, which could be due the possible role of one methylene interrupted diynoic acid system for its radical-scavenging/antioxidant properties of oil. The oil also reduced lipid peroxidation, suppressed reactive oxygen species, extracellular nitric oxide, lactate/pyruvate ratio, and lactase dehydrogenase generated by 3-NP- (100 mM) induced neurotoxicity in PC12 cells, and enhanced the levels of enzymatic and non-enzymatic antioxidants at 40 ?g of gallic acid equivalents. Conclusion The protective effect of pomegranate seed oil might be due to the ability of an oil to neutralize ROS or enhance the expression of antioxidant gene. PMID:25238165

  1. MCL-1 and BCL-xL-dependent resistance to the BCL-2 inhibitor ABT-199 can be overcome by preventing PI3K/AKT/mTOR activation in lymphoid malignancies.

    Science.gov (United States)

    Choudhary, G S; Al-Harbi, S; Mazumder, S; Hill, B T; Smith, M R; Bodo, J; Hsi, E D; Almasan, A

    2015-01-01

    Overexpression of anti-apoptotic BCL-2 family members is a hallmark of many lymphoid malignancies, including chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL) that can be targeted with small molecule inhibitors. ABT-199 is a rationally designed BCL-2 homology (BH)-3 mimetic that specifically binds to BCL-2, but not to MCL-1 and BCL-xL. Although the thrombocytopenia that occurs with navitoclax treatment has not been a problem with ABT-199, clinical trials in CLL could benefit by lowering the ABT-199 concentration through targeting other survival pathways. In this study, we investigated the mechanisms of resistance that develops to ABT-199 therapy by generating ABT-199-resistant (ABT199-R) cell lines via chronic exposure of NHL cell lines to ABT-199. Acquired resistance resulted in substantial AKT activation and upregulation of MCL-1 and BCL-xL levels that sequestered BIM. ABT199-R cells exhibited increased MCL-1 stability and failed to activate BAX in response to ABT-199. The ABT-199 acquired and inherent resistant cells were sensitized to treatment with ABT-199 by inhibitors of the PI3K, AKT, and mTOR pathways, NVP-BEZ235 and GS-1101. NVP-BEZ235, a dual inhibitor of p-AKT and mTOR, reduced MCL-1 levels causing BIM release from MCL-1 and BCL-xL, thus leading to cell death by BAX activation. The PI3K? inhibitor GS-1101 (idelalisib) downregulated MCL-1 and sensitized ABT199-R cells through AKT-mediated BAX activation. A genetic approach, through siRNA-mediated down-regulation of AKT, MCL-1, and BCL-xL, significantly decreased cell survival, demonstrating the importance of these cell survival factors for ABT-199 resistance. Our findings suggest a novel mechanism that modulates the expression and activity of pro-survival proteins to confer treatment resistance that could be exploited by a rational combination therapeutic regimen that could be effective for treating lymphoid malignancies. PMID:25590803

  2. Pyridoxal-5'-phosphate as the catalyst for radical isomerization in reactions of PLP-dependent aminomutases.

    Science.gov (United States)

    Frey, Perry A; Reed, George H

    2011-11-01

    PLP catalyzes the 1,2 shifts of amino groups in free radical-intermediates at the active sites of amino acid aminomutases. Free radical forms of the substrates are created upon H atom abstractions carried out by the 5'-deoxyadenosyl radical. In most of these enzymes, the 5'-deoxyadenosyl radical is generated by an iron-sulfur cluster-mediated reductive cleavage of S-adenosyl-(S)-methionine. However, in lysine 5,6-aminomutase and ornithine 4,5-aminomutase, the radical is generated by homolytic cleavage of the cobalt-carbon bond of adenosylcobalamin. The imine linkages in the initial radical forms of the external aldimines undergo radical addition to form azacyclopropylcarbinyl radicals as central intermediates in the catalytic cycles. In the case of lysine 2,3-aminomutase, the multistep catalytic mechanism is corroborated by direct spectroscopic observation and characterization of a product radical trapped during steady-state turnover. Analogues of the substrate-related radical having substituents adjacent to the radical center to stabilize the unpaired electron are also observed and characterized spectroscopically. A functional allylic analogue of the 5'-deoxyadenosyl radical is observed spectroscopically. A high-resolution crystal structure fully supports the mechanistic proposals. Evidence for a similar free radical mediated amino group transfer in the adenosylcobalamin-dependent lysine 5,6-aminomutase is provided by spectroscopic detection and characterization of radicals generated from the 4-thia analogues of the lysine substrates. This article is part of a Special Issue entitled: Pyridoxal Phospate Enzymology. PMID:21435400

  3. Anesthesia for radical prostatectomy

    Directory of Open Access Journals (Sweden)

    Hadži-?oki? J.

    2005-01-01

    Full Text Available Radical prostatectomy is one of most common treatment options currently recommended for clinically localized prostate cancer. Evaluation of intraoperative and postoperative complications is important in evaluation of relative morbidity of this treatment option. Furthermore, investigation of complications of surgical treatment in correlation with not only surgical technique, but comorbidity, ASA stage and anesthetic technique enables improvements in complete perioperative treatment and decrease of incidence of complications resulting from the procedure. Improvement of anesthetic techniques and use of new anesthetic agents contributes to better outcome of surgical treatment. For radical surgery, combined epidural analgesia and general anesthesia reduces postoperative complications and mortality. Benefits can be conferred most likely by altered coagulation activation in surgery, increased blood flow, reduction of operative stress response. Modalities for reduction of intraoperative blood loss during radical prostatectomy are normovolemic haemodilution, preoperative donation of blood for autologus transfusion and use of erythropoietin for increasing red cell mass.

  4. Anesthesia for radical prostatectomy.

    Science.gov (United States)

    Filimonovic, J; Gvozdic, B; Krivic, B; Acimovic, M; Tulic, C; Hadzi Djokic, J

    2005-01-01

    Radical prostatectomy is one of most common treatment options currently recommended for clinically localized prostate cancer. Evaluation of intraoperative and postoperative complications is important in evaluation of relative morbidity of this treatment option. Furthermore, investigation of complications of surgical treatment in correlation with not only surgical technique, but comorbidity, ASA stage and anesthetic technique enables improvements in complete perioperative treatment and decrease of incidence of complications resulting from the procedure. Improvement of anesthetic techniques and use of new anesthetic agents contributes to better outcome of surgical treatment. For radical surgery, combined epidural analgesia and general anesthesia reduces postoperative complications and mortality. Benefits can be conferred most likely by altered coagulation activation in surgery, increased blood flow, reduction of operative stress response. Modalities for reduction of intraoperative blood loss during radical prostatectomy are normovolemic haemodilution, preoperative donation of blood for autologus transfusion and use of erythropoietin for increasing red cell mass. PMID:16673607

  5. Gangs, Terrorism, and Radicalization

    Directory of Open Access Journals (Sweden)

    Scott Decker

    2011-01-01

    Full Text Available What can street gangs tell us about radicalization and extremist groups? At first glance, these two groups seem to push the boundaries of comparison. In this article, we examine the important similarities and differences across criminal, deviant, and extremist groups. Drawing from research on street gangs, this article explores issues such as levels of explanation,organizational structure, group process, and the increasingly important role of technology and the Internet in the context of radicalization. There are points of convergence across these groups, but it is important to understand the differences between these groups. This review finds little evidence to support the contention that American street gangs are becoming increasingly radicalized. This conclusion is based largely on organizational differences between gangs and terror groups.

  6. Radical transpubic prostatectomy.

    Science.gov (United States)

    Kursh, E D; Resnick, M I

    1984-12-01

    Removal of an adequate wedge of symphysis pubis provides considerably improved exposure for radical prostatectomy. It is safer to remove the symphysis subperiosteally and to transect the bone with an oscillating bone saw or osteotome. The transpubic approach to radical prostatectomy affords the urologist the advantages of 1) early direct ligation of the dorsal vein, 2) reduced incidence of injury to the external urethral sphincter and subsequent urinary incontinence owing to visualization of the urogenital diaphragm, 3) simplified urethrovesical anastomosis and 4) increased opportunity for maintenance of potency by protecting the pelvic nerve plexus as they course in the lateral vascular pedicles. PMID:6502802

  7. Matrix isolation of free radicals from carbohydrates

    International Nuclear Information System (INIS)

    Photolytically produced H radical-atoms in 6 mol dm-3 H2SO4/H2O glasses trapped at 77 K react upon annealing to 130 K with dissolved carbohydrates to form carbon-located free radicals by abstraction of carbon-bound protons. Analysis of electron spin resonance (e.s.r.) spectra at various annealing stages from ?- and ?-D-glucose together with 6,6-d2-D-glucose, 6-deoxy-D-glucose, 2-deoxy-D-glucose, glucose-1-phosphate, D-xylose, D-allose and D-mannosse indicates radical formation at all possible carbon sites with a strong preference for Cl and a somewhat enhanced contribution of C4 over the statistical expectation. The corresponding component spectra are analysed either by spectra isolation or simulation and their parameters are given. Intramolecular radical transformation at temperatures of 140-160 K is explained by acid-catalysed H2O-elimination. The findings are discussed in relation to the radiation-chemistry of aqueous glucose solutions. The authors thus show that the system of photolysed Fe2+ in acidic glasses at low temperatures containing 10 mmol dm-3 carbohydrate is suitable for studying H(D radical)-reactions by means of e.s.r. spectroscopy. Unlike previously used glasses containing carbohydrates, contributions of oxidation and reduction by direct effects or mixtures of direct and indirect effects and phase-effects due to incomplete glass formation are avoided. (author)glass formation are avoided. (author)

  8. Impacts of an unknown daytime nitrous acid source on its daytime concentration and budget, as well as those of hydroxyl, hydroperoxyl, and organic peroxy radicals, in the coastal regions of China

    Directory of Open Access Journals (Sweden)

    Y. Tang

    2015-01-01

    Full Text Available Many field experiments have found high nitrous acid (HONO mixing ratios in both urban and rural areas during daytime, but these high daytime HONO mixing ratios cannot be explained well by gas-phase production, suggesting that an unknown daytime HONO source (Punknown could exist. The formula Punknown ≈ 19.60 × NO2 × J(NO2 was obtained using observed data from 13 field experiments across the globe. The additional HONO sources (i.e. the Punknown, HONO emissions, and nighttime hydrolysis conversion of nitrogen dioxide (NO2 on aerosols were coupled into the WRF-Chem model (Weather Research and Forecasting model coupled with Chemistry to assess the Punknown impacts on the concentrations and budgets of HONO and peroxy (hydroxyl, hydroperoxyl, and organic peroxy radicals (ROx (= OH + HO2 + RO2 in the coastal regions of China. Results indicated that the additional HONO sources produced a significant improvement in HONO and OH simulations, particularly in the daytime. Elevated daytime-mean Punknown values were found in the coastal regions of China, with a maximum of 2.5 ppb h?1 in the Beijing–Tianjin–Hebei region. The Punknown produced a 60–250% increase of OH, HO2 and RO2 near the ground in the major cities of the coastal regions of China, and a 5–48% increase of OH, HO2 and RO2 in the daytime meridional-mean mixing ratios within 1000 m above the ground. When the additional HONO sources were included, the photolysis of HONO was dominated in the OH production rate in Beijing, Shanghai and Guangzhou before 10:00 LST with a maximum of 10.01 [7.26 due to the Punknown] ppb h?1 in Beijing, whereas the reaction of HO2 + NO (nitric oxide was dominated after 10:00 LST with a maximum of 9.38 [7.23] ppb h?1 in Beijing. The whole ROx cycle was accelerated by the additional HONO sources, especially the Punknown. The OH production rate was enhanced by 0.67 [0.64] to 4.32 [3.86] ppb h?1 via the reaction of HO2 + NO, and by 0.85 [0.69] to 4.11 [3.61] ppb h?1 via the photolysis of HONO, and the OH loss rate was enhanced by 0.58 [0.55] to 2.03 [1.92] ppb h?1 via the reaction of OH + NO2 and by 0.31 [0.28] to 1.78 [1.64] ppb h?1 via the reaction of OH + CO (carbon monoxide in Beijing, Shanghai and Guangzhou. Similarly, the additional HONO sources produced an increase of 0.31 [0.28] to 1.78 [1.64] ppb h?1 via the reaction of OH + CO and 0.10 [0.09] to 0.63 [0.59] ppb h?1 via the reaction of CH3O2 (methylperoxy radical + NO in the HO2 production rate, and 0.67 [0.61] to 4.32 [4.27] ppb h?1 via the reaction of HO2 + NO in the HO2 loss rate in Beijing, Shanghai and Guangzhou. The above results suggest that the Punknown considerably enhanced the ROx concentrations and accelerated ROx cycles in the coastal regions of China, and could produce significant increases in concentrations of inorganic aerosols and secondary organic aerosols and further aggravate haze events in these regions.

  9. Impacts of an unknown daytime nitrous acid source on its daytime concentration and budget, as well as those of hydroxyl, hydroperoxyl, and organic peroxy radicals, in the coastal regions of China

    Science.gov (United States)

    Tang, Y.; An, J.; Wang, F.; Li, Y.; Qu, Y.; Chen, Y.; Lin, J.

    2015-01-01

    Many field experiments have found high nitrous acid (HONO) mixing ratios in both urban and rural areas during daytime, but these high daytime HONO mixing ratios cannot be explained well by gas-phase production, suggesting that an unknown daytime HONO source (Punknown) could exist. The formula Punknown ? 19.60 × NO2 × J(NO2) was obtained using observed data from 13 field experiments across the globe. The additional HONO sources (i.e. the Punknown, HONO emissions, and nighttime hydrolysis conversion of nitrogen dioxide (NO2) on aerosols) were coupled into the WRF-Chem model (Weather Research and Forecasting model coupled with Chemistry) to assess the Punknown impacts on the concentrations and budgets of HONO and peroxy (hydroxyl, hydroperoxyl, and organic peroxy) radicals (ROx) (= OH + HO2 + RO2) in the coastal regions of China. Results indicated that the additional HONO sources produced a significant improvement in HONO and OH simulations, particularly in the daytime. Elevated daytime-mean Punknown values were found in the coastal regions of China, with a maximum of 2.5 ppb h-1 in the Beijing-Tianjin-Hebei region. The Punknown produced a 60-250% increase of OH, HO2 and RO2 near the ground in the major cities of the coastal regions of China, and a 5-48% increase of OH, HO2 and RO2 in the daytime meridional-mean mixing ratios within 1000 m above the ground. When the additional HONO sources were included, the photolysis of HONO was dominated in the OH production rate in Beijing, Shanghai and Guangzhou before 10:00 LST with a maximum of 10.01 [7.26 due to the Punknown] ppb h-1 in Beijing, whereas the reaction of HO2 + NO (nitric oxide) was dominated after 10:00 LST with a maximum of 9.38 [7.23] ppb h-1 in Beijing. The whole ROx cycle was accelerated by the additional HONO sources, especially the Punknown. The OH production rate was enhanced by 0.67 [0.64] to 4.32 [3.86] ppb h-1 via the reaction of HO2 + NO, and by 0.85 [0.69] to 4.11 [3.61] ppb h-1 via the photolysis of HONO, and the OH loss rate was enhanced by 0.58 [0.55] to 2.03 [1.92] ppb h-1 via the reaction of OH + NO2 and by 0.31 [0.28] to 1.78 [1.64] ppb h-1 via the reaction of OH + CO (carbon monoxide) in Beijing, Shanghai and Guangzhou. Similarly, the additional HONO sources produced an increase of 0.31 [0.28] to 1.78 [1.64] ppb h-1 via the reaction of OH + CO and 0.10 [0.09] to 0.63 [0.59] ppb h-1 via the reaction of CH3O2 (methylperoxy radical) + NO in the HO2 production rate, and 0.67 [0.61] to 4.32 [4.27] ppb h-1 via the reaction of HO2 + NO in the HO2 loss rate in Beijing, Shanghai and Guangzhou. The above results suggest that the Punknown considerably enhanced the ROx concentrations and accelerated ROx cycles in the coastal regions of China, and could produce significant increases in concentrations of inorganic aerosols and secondary organic aerosols and further aggravate haze events in these regions.

  10. New free radical scavenging neolignans from fruits of Piper attenuatum

    Science.gov (United States)

    Reddy, S. Divya; Siva, Bandi; Poornima, B.; Kumar, D. Anand; Tiwari, Ashok K.; Ramesh, U.; Babu, K. Suresh

    2015-01-01

    Objective: The aim was to study and identify free radicals scavenging and antihyperglycemic principles in fruit of Piper attenuatum. Materials and Methods: Bioassay guided identification of extracts possessing potent free radical scavenging activity, and isolation of compounds was done. Chloroform extract of P. attenuatum possessing potent radical scavenging activity was also evaluated for antihyperglycemic activity following oral glucose tolerance test in rats. Results: Nine neolignans namely, denudatin B (1), iso-4’, 5’-dimethoxy-3, 4-methylenedioxy-2’-oxo-?3’,5’,8’-8.1’-lignan (2), lancifolin D (3), denudatin A (4), wallichinin (5), piperenone (6), lancifolin C (7), 2-oxo-piperol B (8), piperkadsin A (9) and a crotepoxide (10) was identified in Chloroform extract of P. attenuatum. Neolignans (1-9) displayed potent 2, 2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) radical and piperkadsin A (9) also displayed 1, 1-diphenyl-2-picrylhydrazyl radical scavenging activity. Analysis of structure-activity relationship revealed that presence of furan ring and methoxy groups is an important criterion to influence 2, 2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging potentials. Chloroform extract of P. attenuatum fruit could not display antihyperglycemic activity following oral glucose tolerance test in rats. Conclusion: Neolignans present in P. attenuatum fruits are potent free radical scavengers and this is the first report identifying these compounds and activities in this fruit. PMID:25829760

  11. Alkoxy radical radiation products

    International Nuclear Information System (INIS)

    Single crystals of ribitol and 6-methylpurine-riboside were x-irradiated at 4.2 0K. Alkoxy radicals were identified in the radiation products. The g tensor and proton coupling tensors, were determined from ENDOR and ESR studies

  12. Alkoxy radical radiation products

    Science.gov (United States)

    Box, Harold C.; Budzinski, Edwin E.

    1982-06-01

    Single crystals of ribitol and 6-methylpurine-riboside were x-irradiated at 4.2 °K. Alkoxy radicals were identified in the radiation products. The g tensor and proton coupling tensors, were determined from ENDOR and ESR studies. (AIP)

  13. Synthesis, molecular modeling and biological evaluation of novel 2-allyl amino 4-methyl sulfanyl butyric acid as ?-amylase and ?-glucosidase inhibitor

    Science.gov (United States)

    Balan, Kannan; Perumal, Perumal; Sundarabaalaji, Narayanan; Palvannan, Thayumanavan

    2015-02-01

    In the present study 2-allyl amino 4-methyl sulfanyl butyric acid (AMSB) was synthesized in good yield. AMSB was characterized by Fourier transforms infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR) (1H and 13C) and Liquid chromatography mass spectrometry (LCMS). The radical scavenging activity and reducing power assay of AMSB was assessed using 1-1-diphenyl 2-picryl hydrazyl (DPPH), 2,2?-azino-bis (3-ethyl benzothiazoline-6-sulfonic acid) (ABTS) and ferric ion reducing antioxidant power assay (FRAP) and was found to be 44.1, 34.71 and 41.7 ?g/ml respectively. The compound showed effective inhibition against ?-amylase and ?-glucosidase. AMSB was identified to be a reversible mixed noncompetitive inhibitor of ?-amylase and ?-glucosidase. The molecular docking study was carried out to evaluate the specific groove binding properties and affords valuable information of AMSB binding mode in the active site of ?-glucosidase the study may lead to the which leads to the rational design of new class of antidiabetic drugs targeting ?-glucosidase based on AMSB in near future.

  14. Prostate Cancer: Radical Prostatectomy (Surgery)

    Science.gov (United States)

    ... Surgery Surgery What is Radical Prostatectomy (Surgery) for Prostate Cancer? Before and after radical prostatectomy Cancer Research UK ... vessels. They filter fluid from the lymph nodes. Prostate cancer usually spreads first to the soft tissues around ...

  15. Atropisomerism of the Asn ? Radicals Revealed by Ramachandran Surface Topology

    DEFF Research Database (Denmark)

    Gerlei, Klára Z.; Jákli, Imre

    2013-01-01

    C radicals are typically trigonal planar and thus achiral, regardless of whether they originate from a chiral or an achiral C-atom (e.g., C-H + (•)OH ? C• + H2O). Oxidative stress could initiate radical formation in proteins when, for example, the H-atom is abstracted from the C?-carbon of an amino acid residue. Electronic structure calculations show that such a radical remains achiral when formed from the achiral Gly, or the chiral but small Ala residues. However, when longer side-chain containing proteogenic amino acid residues are studied (e.g., Asn), they provide radicals of axis chirality, which in turn leads to atropisomerism observed for the first time for peptides. The two enantiomeric extended backbone structures, •?L and •?D, interconvert via a pair of enantiotopic reaction paths, monitored on a 4D Ramachandran surface, with two distinct transition states of very different Gibbs-free energies: 37.4 and 67.7 kJ/mol, respectively. This discovery requires the reassessment of our understanding on radical formation and their conformational and stereochemical behavior. Furthermore, the atropisomerism of proteogenic amino acid residues should affect our understanding on radicals in biological systems and, thus, reframes the role of the D-residues as markers of molecular aging.

  16. Atropisomerism of the Asn ? radicals revealed by Ramachandran surface topology.

    Science.gov (United States)

    Gerlei, Klára Z; Jákli, Imre; Sz?ri, Milán; Jensen, Svend J Knak; Viskolcz, Béla; Csizmadia, Imre G; Perczel, András

    2013-10-17

    C radicals are typically trigonal planar and thus achiral, regardless of whether they originate from a chiral or an achiral C-atom (e.g., C-H + (•)OH ? C• + H2O). Oxidative stress could initiate radical formation in proteins when, for example, the H-atom is abstracted from the C?-carbon of an amino acid residue. Electronic structure calculations show that such a radical remains achiral when formed from the achiral Gly, or the chiral but small Ala residues. However, when longer side-chain containing proteogenic amino acid residues are studied (e.g., Asn), they provide radicals of axis chirality, which in turn leads to atropisomerism observed for the first time for peptides. The two enantiomeric extended backbone structures, •?L and •?D, interconvert via a pair of enantiotopic reaction paths, monitored on a 4D Ramachandran surface, with two distinct transition states of very different Gibbs-free energies: 37.4 and 67.7 kJ/mol, respectively. This discovery requires the reassessment of our understanding on radical formation and their conformational and stereochemical behavior. Furthermore, the atropisomerism of proteogenic amino acid residues should affect our understanding on radicals in biological systems and, thus, reframes the role of the D-residues as markers of molecular aging. PMID:24015919

  17. In vitro free radical scavenging activity of platinum nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Aki; Kajita, Masashi; Kim, Juewon; Kanayama, Atsuhiro; Miyamoto, Yusei [Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Bioscience Building 402, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562 (Japan); Takahashi, Kyoko; Mashino, Tadahiko, E-mail: yusei74@k.u-tokyo.ac.j [Department of Pharmaceutical Sciences, Faculty of Pharmacy, Keio University, 1-5-30 Shibakoen, Minato, Tokyo 105-8512 (Japan)

    2009-11-11

    A polyacrylic acid (PAA)-protected platinum nanoparticle species (PAA-Pt) was prepared by alcohol reduction of hexachloroplatinate. The PAA-Pt nanoparticles were well dispersed and homogeneous in size with an average diameter of 2.0 {+-} 0.4 nm (n = 200). We used electron spin resonance to quantify the residual peroxyl radical AOO. generated from 2,2-azobis (2-aminopropane) dihydrochloride (AAPH) by thermal decomposition in the presence of O{sub 2} and a spectrophotometric method to quantify the residual 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. PAA-Pt scavenged these two radicals in a dose-dependent manner. Platinum was the functional component. PAA-Pt reduced the rate of oxygen consumption required for linoleic acid peroxidation initiated by AOO. generated from AAPH, indicating inhibition of the propagation of linolate peroxidation. A thiobarbituric acid test also revealed dose-dependent inhibition of the linolate peroxidation by PAA-Pt. Fifty micromolar platinum, as PAA-Pt, completely quenched 250 {mu}M DPPH radical for 5 min. Even when twice diluted in half, the PAA-Pt still quenched 100% of the 250 {mu}M DPPH radical. The scavenging activity of PAA-Pt is durable. These observations suggest that PAA-Pt is an efficient scavenger of free radicals.

  18. A Pair of New Antioxidant Phenolic Acid Stereoisomers Isolated from Danshen Injection (Lyophilized Powder)

    OpenAIRE

    Jing Liu; Jianfeng Zhao; Zhong Dai; Ruichao Lin; Gangli Wang; Shuangcheng Ma

    2014-01-01

    A pair of new phenolic acid stereoisomers, (R)-norsalvianolic acid L (1) and (S)-norsalvianolic acid L (2), was isolated from the Danshen Injection (lyophilized powder). The structural elucidation and stereochemistry determination were achieved by spectroscopic and chemical methods including 1D, 2D NMR (1H-1H COSY, HSQC and HMBC) and circular dichroism experiments. Their antioxidant activities were assessed by the DPPH· and ABTS·+ scavenging methods in vitro with microplate assay. The IC50...

  19. A Modified Method for Studying Behavioral Paradox of Antioxidants and Their Disproportionate Competitive Kinetic Effect to Scavenge the Peroxyl Radical Formation

    Science.gov (United States)

    Masood, Nusrat; Fatima, Kaneez; Luqman, Suaib

    2014-01-01

    We have described a modified method for evaluating inhibitor of peroxyl radicals, a well-recognized and -documented radical involved in cancer initiation and promotion as well as diseases related to oxidative stress and ageing. We are reporting hydrophilic and lipophilic as well as natural and synthetic forms of antioxidants revealing a diversified behaviour to peroxyl radical in a dose-dependent manner (1?nM–10??M). A simple kinetic model for the competitive oxidation of an indicator molecule (ABTS) and a various antioxidant by a radical (ROO•) is described. The influences of both the concentration of antioxidant and duration of reaction (70?min) on the inhibition of the radical cation absorption are taken into account while determining the activity. The induction time of the reaction was also proposed as a parameter enabling determination of antioxidant content by optimizing and introducing other kinetic parameters in 96-well plate assays. The test evidently improves the original PRTC (peroxyl radical trapping capacity) assay in terms of the amount of chemical used, simultaneous tracking, that is, the generation of the radical taking place continually and the kinetic reduction technique (area under curve, peak value, slope, and Vmax). PMID:24672395

  20. Radical mechanisms of enzymatic catalysis.

    Science.gov (United States)

    Frey, P A

    2001-01-01

    Two classes of enzymatic mechanisms that proceed by free radical chemistry initiated by the 5'-deoxyadenosyl radical are discussed. In the first class, the mechanism of the interconversion of L-lysine and L-beta-lysine catalyzed by lysine 2,3-aminomutase (LAM) involves four radicals, three of which have been spectroscopically characterized. The reversible formation of the 5'-deoxyadenosyl radical takes place by the chemical cleavage of S-adenosylmethionine (SAM) reacting with the [4Fe-4S]+ center in LAM. In other reactions of SAM with iron-sulfur proteins, SAM is irreversibly consumed to generate the 5'-deoxyadenosyl radical, which activates an enzyme by abstracting a hydrogen atom from an enzymatic glycyl residue to form a glycyl radical. The glycyl radical enzymes include pyruvate formate-lyase, anaerobic ribonucleotide reductase from Escherichia coli, and benzylsuccinate synthase. Biotin synthase and lipoate synthase are SAM-dependent [4Fe-4S] proteins that catalyze the insertion of sulfur into unactivated C-H bonds, which are cleaved by the 5'-deoxyadenosyl radical from SAM. In the second class of enzymatic mechanisms using free radicals, adenosylcobalamin-dependent reactions, the 5'-deoxyadenosyl radical arises from homolytic cleavage of the cobalt-carbon bond, and it initiates radical reactions by abstracting hydrogen atoms from substrates. Three examples are described of suicide inactivation through the formation of exceptionally stable free radicals at enzymatic active sites. PMID:11395404

  1. Resonant cavity spectroscopy of radical species

    Science.gov (United States)

    Ritchie, Grant

    2015-04-01

    Photo-oxidation in the troposphere is highly complex, being initiated by short lived radical species, in the daytime dominated by the hydroxyl radical, OH, with contributions from Cl atoms, and at night by either NO3 radicals or ozone. Chemical oxidation cycles, which couple OH, HO2 and peroxy (RO2) radical species, remove primary emitted trace species which are harmful to humans or to the wider environment. However, many of the secondary products produced by atmospheric photo-oxidation are also directly harmful, for example O3, NO2, acidic and multifunctional species, many of which are of low volatility and are able to partition effectively to the condensed phase, creating secondary organic aerosol (SOA), which contributes a significant fraction of tropospheric aerosol, with associated impacts on climate and human health. The accuracy of atmospheric models to predict these impacts necessarily requires accurate knowledge of the chemical oxidative cycling. Two of the simplest intermediates are the hydroperoxy radical, HO2, and the smallest and dominant organic peroxy radical, CH3O2, formed directly by the reactions of OH with CO/O2 and CH4/O2, respectively, and indirectly following the oxidation of larger VOCs. OH, HO2 and RO2 (collectively known as ROx) are rapidly cycled, being at the centre of tropospheric oxidation, and hence are some of the best targets for models to compare with field data. The reaction of HO2 and RO2 with NO constitutes the only tropospheric in-situ source of O3. Despite their importance, neither HO2 nor CH3O2 is measured directly in the atmosphere. HO2 is only measured indirectly following its conversion to OH and CH3O2 is not measured at all. Typically only the sum of RO2 radicals is measured, making no distinction between different organic peroxy radicals. This contribution will detail recent studies using (i) optical feedback cavity enhanced absorption spectroscopy with both quantum and inter-band cascade lasers in the mid-IR, and (ii) near-IR diode laser based noise immune cavity enhanced heterodyne molecular spectroscopy as potential methods for the direct detection of HO2 and CH3O2 at atmospheric levels.

  2. RADICAL SCAVENGING POTENTIAL OF CLEOME VISCOSA L. AND CLEOME BURMANNI W. & A. (CLEOMACEAE

    Directory of Open Access Journals (Sweden)

    Lakshmi S. Pillai* and Bindu R. Nair

    2013-02-01

    Full Text Available The present study evaluates the reactive oxygen species (ROS scavenging and in vitro antioxidant activities of two species of Cleome, C. viscosa and C. burmanni. The antioxidant potential of the methanol extracts of species of Cleome was tested using different assays such as FRAP, DPPH, ABTS, hydroxyl, superoxide, nitric oxide, and hydrogen peroxide. The extracts gave positive results for all the assays and the radical scavenging ability was detected to be comparable to those of the corresponding standards. Quantitative estimation of antioxidant phytochemicals, such as phenols, flavonoids and proanthocyanidins were also done in both species of Cleome. The results revealed that the phytochemicals content was greater in C. viscosa when compared to C. burmanni.

  3. ABT-737 increases tyrosine kinase inhibitor-induced apoptosis in chronic myeloid leukemia cells through XIAP downregulation and sensitizes CD34(+) CD38(-) population to imatinib.

    Science.gov (United States)

    Airiau, Kelly; Mahon, François-Xavier; Josselin, Marina; Jeanneteau, Marie; Turcq, Beatrice; Belloc, Francis

    2012-05-01

    Chronic myeloid leukemia (CML) tumorigenicity is driven by the oncogenic BCR-ABL tyrosine kinase. Specific tyrosine kinase inhibitors (TKI) have been designed and are now used for the treatment of CML. These TKI induce apoptosis in leukemic cells in a BIM-dependent mechanism. We hypothesized that an increase in BIM activity could sensitize CML cells to TKI. We blocked the anti-apoptotic proteins of the Bcl-2 family by using ABT-737, a Bcl-2 and Bcl-XL inhibitor. ABT-737 modified Bcl-2 protein interactions toward a pro-apoptotic phenotype. Its combination with TKI resulted in a strong synergism in CML cell lines. The association also induced a large decrease in X-linked inhibitor of apoptosis (XIAP), followed by caspase-3 activation. This XIAP decrease was due to post-translational events. The mitochondrial serine protease HtrA2/Omi was identified as being responsible for this off-target effect. Then, ABT-737 and TKI cooperate at several levels to induce apoptosis of CML cells lines, and the benefit of this association was also observed in CML hematopoietic progenitors. Interestingly, a lethal effect was also observed in the more immature CD34(+)CD38(-) TKI-insensitive population. Combination therapy might by an interesting strategy for the treatment of CML patients. PMID:22240609

  4. The Reaction of Acetyl Peroxy Radical with Aldehyde: Impact on the OH Radical Model Simulation

    Science.gov (United States)

    Huang, D.; Chen, Z.

    2014-12-01

    Understanding the budget of OH (hydroxyl radical) is very important for investigating the atmospheric oxidation capacity, aerosol formation and climate change. Recent studies indicate that there may be a great gap between the modeled and measured OH concentrations in some rural forest areas. This gap may result from our incomplete knowledge about the oxidation mechanism of volatile organic compounds (VOCs). Here, we suggest that acetyl peroxy radical (CH3C(O)OO•), the OH-initiated oxidation intermediate of most VOCs, can take the H-atom from the aldehyde group to form corresponding peroxy carboxylic acids. This reaction has not been concerned in the atmosphere. The acetyl peroxy radical may share the "oxidation responsibility" of OH, and help saving OH from being consumed by aldehyde. Using a box model coupled with the isoprene-OH reaction mechanism selected from MCM v3.2, we get OH saving ratio (SROH) when we compare the modeled OH levels in the presence and absence of the reaction of acetyl peroxy radical with aldehyde. We find that SROH is not a constant but a function of OH production rate, reaction time, isoprene concentration and the ratio of aldehyde to isoprene. It is expected that CH3C(O)OO• radical, a non-OH oxidant, plays an important role in maintaining the oxidation capacity of the troposphere.

  5. Gangs, Terrorism, and Radicalization

    OpenAIRE

    Scott Decker; David Pyrooz

    2011-01-01

    What can street gangs tell us about radicalization and extremist groups? At first glance, these two groups seem to push the boundaries of comparison. In this article, we examine the important similarities and differences across criminal, deviant, and extremist groups. Drawing from research on street gangs, this article explores issues such as levels of explanation,organizational structure, group process, and the increasingly important role of technology and the Internet in the context of radi...

  6. Free-Radical-Scavenging, Antityrosinase, and Cellular Melanogenesis Inhibitory Activities of Synthetic Isoflavones.

    Science.gov (United States)

    Lu, Tzy-Ming; Ko, Horng-Huey; Ng, Lean-Teik; Hsieh, Yen-Pin

    2015-06-01

    In this study, we examined the potential of synthetic isoflavones for application in cosmeceuticals. Twenty-five isoflavones were synthesized and their capacities of free-radical-scavenging and mushroom tyrosinase inhibition, as well as their impact on cell viability of B16F10 murine melanoma cells and HaCaT human keratinocytes were evaluated. Isoflavones that showed significant mushroom tyrosinase inhibitory activities were further studied on reduction of cellular melanin formation and antityrosinase activities in B16F10 melanocytes in vitro. Among the isoflavones tested, 6-hydroxydaidzein (2) was the strongest scavenger of both ABTS(.) (+) and DPPH(.) radicals with SC50 values of 11.3±0.3 and 9.4±0.1??M, respectively. Texasin (20) exhibited the most potent inhibition of mushroom tyrosinase (IC50 14.9±4.5??M), whereas retusin (17) showed the most efficient inhibition both of cellular melanin formation and antityrosinase activity in B16F10 melanocytes, respectively. In summary, both retusin (17) and texasin (20) exhibited potent free-radical-scavenging capacities as well as efficient inhibition of cellular melanogenesis, suggesting that they are valuable hit compounds with potential for advanced cosmeceutical development. PMID:26080742

  7. Lycopene inhibits the isomerization of ?-carotene during quenching of singlet oxygen and free radicals.

    Science.gov (United States)

    Heymann, Thomas; Heinz, Philipp; Glomb, Marcus A

    2015-04-01

    The present study aimed to investigate the influence of singlet oxygen and radical species on the isomerization of carotenoids. On the one hand, lycopene and ?-carotene standards were incubated with 1,4-dimethylnaphthalene-1,4-endoperoxide that produced singlet oxygen in situ. (13Z)- and (15Z)-?-carotene were preferentially generated at low concentrations of singlet oxygen, while high concentrations resulted in formation of (9Z)-?-carotene. The addition of different concentrations of lycopene led to the same isomerization progress of ?-carotene, but resulted in a decreased formation of (9Z)-?-carotene and retarded degradation of (all-E)-?-carotene. On the other hand, isomerization of ?-carotene and lycopene was induced by ABTS-radicals, too. As expected from the literature, chemical quenching was observed especially for lycopene, while physical quenching was preferred for ?-carotene. Mixtures of ?-carotene and lycopene resulted in a different isomerization progress compared to the separate ?-carotene model. As long as lycopene was present, almost no isomerization of ?-carotene was triggered; after that, strong formation of (13Z)-, (9Z)-, and (15Z)-?-carotene was initiated. In summary, lycopene protected ?-carotene against isomerization during reactions with singlet oxygen and radicals. These findings can explain the pattern of carotenoid isomers analyzed in fruits and vegetables, where lycopene containing samples showed higher (all-E)/(9Z)-?-carotene ratios, and also in in vivo samples such as human blood plasma. PMID:25803572

  8. Inhibitory activities of soluble and bound millet seed phenolics on free radicals and reactive oxygen species.

    Science.gov (United States)

    Chandrasekara, Anoma; Shahidi, Fereidoon

    2011-01-12

    Oxidative stress, caused by reactive oxygen species (ROS), is responsible for modulating several pathological conditions and aging. Soluble and bound phenolic extracts of commonly consumed millets, namely, kodo, finger (Ravi), finger (local), foxtail, proso, little, and pearl, were investigated for their phenolic content and inhibition of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and ROS, namely, hydroxyl radical, peroxyl radical, hydrogen peroxide (H(2)O(2)), hypochlorous acid (HOCl), and singlet oxygen ((1)O(2)). Inhibition of DPPH and hydroxyl radicals was detrmined using electron paramagnetic resonance (EPR) spectroscopy. The peroxyl radical inhibitory activity was measured using the oxygen radical absorbance capacity (ORAC) assay. The scavenging of H(2)O(2), HOCl, and (1)O(2) was evaluated using colorimetric methods. The results were expressed as micromoles of ferulic acid equivalents (FAE) per gram of grain on a dry weight basis. In addition, major hydroxycinnamic acids were identified and quantified using high-performance liquid chromatography (HPLC) and HPLC-mass spectrometry (MS). All millet varieties displayed effective radical and ROS inhibition activities, which generally positively correlated with phenolic contents, except for hydroxyl radical. HPLC analysis revealed the presence of ferulic and p-coumaric acids as major hydroxycinnamic acids in phenolic extract and responsible for the observed effects. Bound extracts of millet contributed 38-99% to ROS scavenging, depending on the variety and the test system employed. Hence, bound phenolics must be included in the evaluation of the antioxidant activity of millets and other cereals. PMID:21133411

  9. New knowledge on the antiglycoxidative mechanism of chlorogenic acid.

    Science.gov (United States)

    Fernandez-Gomez, Beatriz; Ullate, Monica; Picariello, Gianluca; Ferranti, Pasquale; Mesa, Maria Dolores; Del Castillo, Maria Dolores

    2015-06-10

    The role of chlorogenic acid (CGA) in the formation of advanced glycation end-products (AGEs) (glycoxidation reaction) was studied. Model systems composed of bovine serum albumin (BSA) (1 mg mL(-1)) and methylglyoxal (5 mM) under mimicked physiological conditions (pH 7.4, 37 °C) were used to evaluate the antiglycoxidative effect of CGA (10 mM). The stability of CGA under reaction conditions was assayed by HPLC and MALDI-TOF MS. The glycoxidation reaction was estimated by analysis of free amino groups by the OPA assay, spectral analysis of fluorescent AGEs and total AGEs by ELISA, and colour formation by absorbance at 420 nm. Structural changes in protein were evaluated by analysis of phenol bound to the protein backbone using the Folin reaction, UV-Vis spectral analysis and MALDI-TOF-MS, while changes in protein function were measured by determining the antioxidant capacity using the ABTS radical cation decolourisation assay. CGA was isomerised and oxidised under our experimental conditions. Evidence of binding between BSA and multiple CGA and/or its derivative molecules (isomers and oxidation products) was found. CGA inhibited (p < 0.05) the formation of fluorescent and total AGEs at 72 h of reaction by 91.2 and 69.7%, respectively. The binding of phenols to BSA significantly increased (p < 0.001) its antioxidant capacity. Correlations between free amino group content, phenol bound to protein and antioxidant capacity were found. Results indicate that CGA simultaneously inhibits the formation of potentially harmful compounds (AGEs) and promotes the generation of neoantioxidant structures. PMID:26037734

  10. The role of the acidity of N-heteroaryl sulfonamides as inhibitors of bcl-2 family protein-protein interactions.

    Science.gov (United States)

    Touré, B Barry; Miller-Moslin, Karen; Yusuff, Naeem; Perez, Lawrence; Doré, Michael; Joud, Carol; Michael, Walter; DiPietro, Lucian; van der Plas, Simon; McEwan, Michael; Lenoir, Francois; Hoe, Madelene; Karki, Rajesh; Springer, Clayton; Sullivan, John; Levine, Kymberly; Fiorilla, Catherine; Xie, Xiaoling; Kulathila, Raviraj; Herlihy, Kara; Porter, Dale; Visser, Michael

    2013-02-14

    Overexpression of the antiapoptotic members of the Bcl-2 family of proteins is commonly associated with cancer cell survival and resistance to chemotherapeutics. Here, we describe the structure-based optimization of a series of N-heteroaryl sulfonamides that demonstrate potent mechanism-based cell death. The role of the acidic nature of the sulfonamide moiety as it relates to potency, solubility, and clearance is examined. This has led to the discovery of novel heterocyclic replacements for the acylsulfonamide core of ABT-737 and ABT-263. PMID:24900652

  11. Reaction of radiolytically generated hydroxy radicals with maleic hydrazide

    International Nuclear Information System (INIS)

    Pulse radiolysis has been used to study the reaction of hydroxyl radicals with maleic hydrazide. The rate constants of OH with the neutral hydrazide and its monoanion were found to be (2.9 +- 0.1) x 109 dm3 mol-1 s-1 and (4.2 +- 0.1) x 109 dm3 mol-1 s-1, respectively. In the reaction with the hydrazide monoanion 2/3 of the OH yield diazasemiquinone radicals. The remaining 1/3 of the OH radicals are proposed to yield an OH adduct to the C=C bond. In the reaction with the neutral hydrazide no diazasemiquinone was detected. The radicals generated in this reaction are proposed to be OH adducts. They are found to react with O2 to yield peroxy radicals. From product analysis it is concluded that O2 reacts with the OH adduct of the monoanion to yield a peroxy radical. The reaction of this peroxy radical with the diazasemiquinone is proposed to yield maleic acid. (author)

  12. A novel phenolic acid from the fruits of Rosa soulieana.

    Science.gov (United States)

    He, Wenjun; Yang, Chunyan; Wang, Mingkui; Li, Fu

    2014-01-01

    From the n-BuOH-soluble fraction of a MeOH extract of the fruits of Rosa soulieana, one new phenolic glucoside (1) was isolated along with five known compounds, comprising two lignin glycosides, two flavonoid glycosides and a phenolic glycoside. The chemical structure of the new compound was elucidated by extensive spectroscopic analyses, including ESI-MS, UV, IR, (1)H and (13)C NMR, DEPT and 2D NMR (HSQC and HMBC). All the isolated compounds were evaluated for their antioxidant activity by using ABTS (2,2'-azino-bis(3-ethylbenzoline-6-sulfonic acid)) assay. Among these compounds, 1, 3 and 6 exhibited strong scavenging activity in ABTS(·+)(SC50 = 102.10, 193.85, 65.38 ?mol/L, respectively) compared with the positive control l-ascorbic acid (Vc) (SC50 = 117.16 ?mol/L). PMID:24831176

  13. Antioxidant and Free Radical Scavenging Properties of Twelve Traditionally Used Indian Medicinal Plants

    OpenAIRE

    AQIL, Farrukh; AHMAD, Iqbal; MEHMOOD, Zafar

    2006-01-01

    The methanolic crude extracts of 12 traditionally used Indian medicinal plants were screened for their antioxidant and free radical scavenging properties using a-tocopherol and butylated hydroxy toluene (BHT) as standard antioxidants. Antioxidant activity was measured by ferric thiocyanate (FTC) assay and compared with the thiobarbituric acid (TBA) method. Free radical scavenging activity was evaluated using diphenyl picryl hydrazyl (DPPH) radicals. The overall antioxidant activity of Lawsoni...

  14. Formation of free radicals in the photochemical modification of antifrictional plastic compositions

    International Nuclear Information System (INIS)

    Using ESR spectroscopy the authors investigated the photolysis and radical composition of a plastic lubricant composed of polyethylene, perfluoroalkylpolyester 240, oleic acid, mineral oil, and benzophenone. The spectra are comprehensively analyzed. Hyperfine structure and spin trapping are given for the polyalkyl radicals. The photochemical modification of the lubricant leading to these radicals, and their reaction with oxygen, are determined to be responsible for the enhanced adhesion of the plasticizers to the polymer

  15. Synthesis and radical-scavenging activity of a dimethyl catechin analogue.

    Science.gov (United States)

    Imai, Kohei; Nakanishi, Ikuo; Ohno, Akiko; Kurihara, Masaaki; Miyata, Naoki; Matsumoto, Ken-Ichiro; Nakamura, Asao; Fukuhara, Kiyoshi

    2014-06-01

    Catechin analogue 1 with methyl substituents ortho to the catechol hydroxyl groups was synthesized to improve the antioxidant ability of (+)-catechin. The synthetic scheme involved a solid acid catalyzed Friedel-Crafts coupling of a cinnamyl alcohol derivative to 3,5-dibenzyloxyphenol followed by hydroxylation and then cyclization through an intermediate orthoester. The antioxidative radical scavenging activity of 1 against galvinoxyl radical, an oxyl radical, was found to be 28-fold more potent than (+)-catechin. PMID:24792463

  16. Antioxidant capacity automatic assay based on inline photogenerated radical species from L-glutathione-capped CdTe quantum dots.

    Science.gov (United States)

    Rodrigues, Daniela M C; Ribeiro, David S M; Frigerio, Christian; Rodrigues, S Sofia M; Santos, João L M; Prior, João A V

    2015-08-15

    This work aimed at the development of a methodology implemented in an automatic flow system for determination of the antioxidant capacity in food samples, based on the luminol oxidation by inline photogenerated radical species from cadmium telluride nanoparticles capped with L-glutathione. Radical species were generated inline by a high-power visible light obtained by Light Emitting Diodes (LEDs) assembled in a multipumping flow system (MPFS). The use of visible light instead of UV radiation allowed the development of a new methodology for antioxidant capacity determination, more environment friendly and to circumvent the risk for UV photo-induced degradation of sample antioxidant compounds. Additionally, the formation of superoxide radical species was theoretically predicted considering the variation of the redox potential with the size of CdTe QDs and the values of redox potential of the oxidizing and oxidable species present in the irradiated medium. The obtained results of trolox equivalent antioxidant capacity (TEAC) from the analysis of commercial beverages were compared with the results of ABTS and DPPH batch assays through Spearman's-Rho correlation coefficients and no correlation was found (for ABTS: ?=0.2, p<0.6 and for DPPH: ?=0.5, p<0.1) since the mechanism of action of the proposed methodology was based on the scavenging capacity of ROS species rather than the reduction of a colored oxidant. An analytical linear response range between 0.0001 and 0.005mmol L(-1) of trolox and a limit of detection of 0.00005mmol L(-1) was found. The QDs based MPFS methodology allowed a determination rate of about 79h(-1), a total waste generation of 20.5mL h(-1) and the consumption of 0.100mg h(-1) of QDs and 2.1mg h(-1) of luminol. PMID:25966406

  17. a Free Radical

    Science.gov (United States)

    Carrington, Alan

    2001-10-01

    This chapter describes my research career, spanning the period from 1955 to 2000. My initial PhD work at the University of Southampton was concerned with the electronic structure and spectra of transition metal complexes and included studies of the electronic spin resonance (ESR) spectra of magnetically dilute single crystals. After a year at the University of Minnesota, I went to Cambridge University and for the next six years studied the ESR spectra of liquid phase organic free radicals. I commenced work on the microwave magnetic resonance (MMR) spectra of gaseous free radicals in 1965, and this work continued until 1975. I moved from Cambridge to Southampton in 1967. In 1975 I turned to the study of gas phase molecular ions, using ion beam methods. In the earlier years of this period I concentrated on simple fundamental species like H+2, HD+, and H+3. In the later years until my retirement in 1999, I concentrated on the observation and analysis of microwave spectra involving energy levels lying very close to a dissociation asymptote. DEDICATION This chapter is dedicated to the memory of Harry E. Radford, who died while it was being written. Harry was a quiet and shy man, who often worked alone and never indulged in self-promotion. So far as I know, he was never awarded any medals or prizes, nor elected to any academies or learned societies. Nevertheless he was an experimentalist of the highest originality and quality, a theorist of true intellectual depth, and a remarkable pioneer in many of the techniques of studying free radicals that are now commonplace.

  18. Borra de café colombiano (Coffea arabica) como fuente potencial de sustancias con capacidad antirradicales libres in vitro / Colombian spent coffee grounds (Coffea arabica) as a potential source of substances with free radicals capacity in vitro

    Scientific Electronic Library Online (English)

    Miguel A, Puertas-Mejía; Paola, Villegas-Guzmán; Benjamín, Alberto Rojano.

    2013-09-01

    Full Text Available Introducción: Coffea arabica L., además de su importancia comercial, también se considera una planta medicinal, porque presenta propiedades biológicas diversas, pero por su comercialización como bebida genera muchos subproductos. La borra es uno de estos, que se obtiene por la preparación de la bebi [...] da, contiene una concentración significativa de compuestos polifenólicos y, por tanto, la recuperación de estas sustancias a partir de un residuo sin valor, sería potencialmente útil para la industria farmacéutica y alimentaria. Objetivos: recuperar compuestos fenólicos a partir de la borra de café y darle un valor agregado a un residuo de origen vegetal, como fuente de componentes con capacidad antirradicales libres in vitro. Métodos: la borra de café previamente secada se sometió a extracciones sólido-líquido usando diferentes sistemas de solventes. Se evaluaron las propiedades antioxidantes in vitro usando los métodos del catión radical del ácido 2,2´-azino-bis (3-etilbenzotiazoline-6-sulfónico) y del radical 1,1-difenil-2-picrilhidracilo. Se usó cromatografía líquida de alta resolución acoplada a espectrometría de masas para la caracterizaron de los principales componentes. Resultados: todos los extractos obtenidos mostraron buena capacidad antioxidante, con el extracto de etanol:agua como el mejor, seguido del extracto de metanol acidulado. Sin embargo, la capacidad antioxidante de la fracción en diclorometano del extracto etanol:agua resultó menor que la presentada por la taza de café. Se identificaron los ácidos clorogénico, isoclorogénico y feruloilquínico como los principales componentes de la borra de café. Conclusiones: todos los extractos presentaron buena capacidad protectora contra radicales libres. La borra de café, considerada un desecho obtenido del procesamiento industrial, se puede convertir en materia prima para la recuperación de sustancias antioxidantes; lo cual genera grandes expectativas sobre su posible uso en la industria farmacéutica y alimentaria, y le da al café un valor agregado importante. Abstract in english Introduction: besides its commercial importance, Coffee arabica L. is also considered a medicinal plant due to its various biological properties, but its marketing produces a large amount of residues. Spent coffee grounds are one of these residues, which are obtained after the preparation of the dri [...] nk and contain a significant concentration of polyphenolic compounds. Therefore, the recovery of these substances costless residual will be potentially useful for food and pharmaceutical industry. Objectives: to recover polyphenolic compounds from spent coffee grounds and to give an added value to a vegetable waste as a source of substances with free radicals capacity in vitro. Methods: dehydrated spent coffee grounds were subjected to solid-liquid extraction using different solvent systems. Antioxidant properties were evaluated in vitro using the radical monocation 2,2´-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and the stable free radical 2-2-diphenyl-1-picrylhydrazyl (DPPH). Liquid chromatography coupled to mass spectrometry was applied to characterize the main compounds. Results: all the extracts obtained showed a good antioxidant capacity with ethanol-water extract, followed by acidulated methanol extract. However, the antioxidant capacity of the ethanol-water extract was lower than coffee beverage. Chlorogenic, isochlorogenic and feruloylquinic acids were identified as the main compounds present in spent coffee grounds. Conclusions: all extracts showed a significant protection effect against free radicals; spent coffee ground, which is considered an undesirable solid waste from industrial processing, could be an add-value raw material in the recovery of antioxidant substances which generates great expectations about its possible use in the pharmaceutical and food industry and gives coffee an important added value.

  19. A more radical solution.

    Science.gov (United States)

    Lachmann, Peter J

    2015-01-01

    The current modifications to licensing procedures still leave a basically flawed system in place. A more radical solution is proposed that involves dispensing with Phase 3 trials and making medicines available at the end of Phase 2 to those who are fully informed of the potential risks and benefits and wish to take part in this novel procedure. The advantages include a shorter development time, lower development costs and allowing smaller companies to take medicines to the clinic. The principal obstacle is that medicines are subject to strict liability rather than the tort of negligence - and this will have to be amended in due course. PMID:25925882

  20. Electromeric Rhodium Radical Complexes

    OpenAIRE

    F.F. Puschmann; J. Harmer; Stein, D; H. R\\xfcegger; de Bruin, B; H. Gr\\xfctzmacher

    2010-01-01

    "Chemical Equation Presented" Radical changes: One single P-Rh-P angle determines whether the odd electron in the paramagnetic complex [Rh(trop2PPh)(PPh3)] is delocalized over the whole molecule (see picture, blue) or is localized on the P - Rh unit (red). The two energetically almost degenerate electromers exist in a fast equilibrium, and the "red" complex has the highest spin density at Rh of all low valent Rh complexes observed to date. © 2010 Wiley-VCH Verlag GmbH and Co. KGaA.

  1. Competitive reduction of perferrylmyoglobin radicals by protein thiols and plant phenols.

    Science.gov (United States)

    Jongberg, Sisse; Lund, Marianne N; Skibsted, Leif H; Davies, Michael J

    2014-11-19

    Radical transfer from perferrylmyoglobin to other target species (myofibrillar proteins, MPI) and bovine serum albumin (BSA), extracts from green tea (GTE), maté (ME), and rosemary (RE), and three phenolic compounds, catechin, caffeic acid, and carnosic acid) was investigated by electron paramagnetic resonance (EPR) spectroscopy to determine the concentrations of plant extracts required to protect against protein oxidation. Blocking of MPI thiol groups by N-ethylmaleimide was found to reduce the rate of reaction of MPI with perferrylmyoglobin radicals, signifying the importance of protein thiols as radical scavengers. GTE had the highest phenolic content of the three extracts and was most effective as a radical scavenger. IC50 values indicated that the molar ratio between phenols in plant extract and MPI thiols needs to be >15 in order to obtain efficient protection against protein-to-protein radical transfer in meat. Caffeic acid was found most effective among the plant phenols. PMID:25343706

  2. Competitive reduction of perferrylmyoglobin radicals by protein thiols and plant phenols

    DEFF Research Database (Denmark)

    Jongberg, Sisse; Lametsch, Marianne Lund

    2014-01-01

    Radical transfer from perferrylmyoglobin to other target species (myofibrillar proteins, MPI) and bovine serum albumin (BSA), extracts from green tea (GTE), maté (ME), and rosemary (RE), and three phenolic compounds, catechin, caffeic acid, and carnosic acid) was investigated by electron paramagnetic resonance (EPR) spectroscopy to determine the concentrations of plant extracts required to protect against protein oxidation. Blocking of MPI thiol groups by N-ethylmaleimide was found to reduce the rate of reaction of MPI with perferrylmyoglobin radicals, signifying the importance of protein thiols as radical scavengers. GTE had the highest phenolic content of the three extracts and was most effective as a radical scavenger. IC50 values indicated that the molar ratio between phenols in plant extract and MPI thiols needs to be >15 in order to obtain efficient protection against protein-to-protein radical transfer in meat. Caffeic acid was found most effective among the plant phenols.

  3. The specificities of radical innovation

    OpenAIRE

    Motte, Damien; Yannou, Bernard; Bja?rnemo, Robert

    2011-01-01

    In this paper, we investigate a special case of new product development (NDP), that of radical innovation. When a company desires to go outside a current saturated market, it is necessary to offer a new product which is radically different from the competition. If successful, the offering will create a new market that the company can expect to dominate a least for a while until the competition strikes back. A radical NPD has several characteristics that are quite unique and distinct from othe...

  4. ABT Ballet Dictionary

    Science.gov (United States)

    How many times have you heard or used the terms "pirouette" or "pas de deux" without really knowing what they meant? A number of words related to ballet have made their way into common usage, although many people may not know what they really mean or what they would look like if performed by a trained dancer. The American Ballet Theatre has created this Online Ballet Dictionary of 170 terms with assistance from its own dancers who were asked to "show us how it is supposed to be done." The resulting site combines Quicktime movies of dancers demonstrating steps with terms drawn from the Technical Manual and Dictionary of Classical Ballet. While not every term is accompanied by a movie, each term includes a definition and pronunciation guide, as well as occasional cross references to other terms in the dictionary.

  5. Chemical and radiation-chemical radical reactions in lignocellulose materials

    Science.gov (United States)

    Kuzina, Svetlana I.; Shilova, Irina A.; Mikhailov, Al'fa I.

    2011-09-01

    Chemical and radiation-chemical radical reactions in lignocellulose materials were explored by 3-cm and 2-mm ESR spectroscopy. Background (intrinsic) singlet signals at g=2.003 from wood pulp and lignin and those arising during reaction of lignocellulose materials with acids and chlorine were attributed to radicals with conjugated C?C bonds. The 2-mm ESR signal with 3D anisotropy of g-factor from o-semiquinone radical ions formed in reaction of lignin with NaOH was recorded for the first time. The singlet signals derived from cellulose ?-irradiated at 77 K and marked out during post-thermal reactions were assigned to radicals with conjugated bonds. In wetted cellulose, a triplet signal with ??H?2.7 mT and imposed quadruplet structure (0.5-0.7 mT) from three ?-protons was detected at 300 K and attributed to ? 4-radicals. The triplet signals derived from ? 2- and ? 3-radicals in pyranose cycles of cellulose exhibited higher values of ??H (3.0-3.2 mT) and lower thermal stability (up to 250 K). In radiolyzed cotton pulp, detected were ESR signals derived from formyl radicals formed upon rupture of the ? 5?? 6 bond in pyranose cycles. Heating up irradiated samples under ? 2 was accompanied by formation of peroxide radicals. Photoinduced recombination of trapped electrons with ? 1-radicals was found to proceed as a chain reaction with a kinetic length of about 25 units. Photolysis ( ??360 nm) of radiolyzed cellulose enhanced the disclosure of pyranose cycles and, as a result, the evolution of CO 2 by a factor of 2-2.5.

  6. Chemical and radiation-chemical radical reactions in lignocellulose materials

    International Nuclear Information System (INIS)

    Chemical and radiation-chemical radical reactions in lignocellulose materials were explored by 3-cm and 2-mm ESR spectroscopy. Background (intrinsic) singlet signals at g=2.003 from wood pulp and lignin and those arising during reaction of lignocellulose materials with acids and chlorine were attributed to radicals with conjugated C--C bonds. The 2-mm ESR signal with 3D anisotropy of g-factor from o-semiquinone radical ions formed in reaction of lignin with NaOH was recorded for the first time. The singlet signals derived from cellulose ?-irradiated at 77 K and marked out during post-thermal reactions were assigned to radicals with conjugated bonds. In wetted cellulose, a triplet signal with ??H?2.7 mT and imposed quadruplet structure (0.5-0.7 mT) from three ?-protons was detected at 300 K and attributed to S4-radicals. The triplet signals derived from S2- and S3-radicals in pyranose cycles of cellulose exhibited higher values of ??H (3.0-3.2 mT) and lower thermal stability (up to 250 K). In radiolyzed cotton pulp, detected were ESR signals derived from formyl radicals formed upon rupture of the S5--S6 bond in pyranose cycles. Heating up irradiated samples under O2 was accompanied by formation of peroxide radicals. Photoinduced recombination of trapped electrons with S1-radicals was found to proceed as a chain reaction with a kinetic length in reaction with a kinetic length of about 25 units. Photolysis (??360 nm) of radiolyzed cellulose enhanced the disclosure of pyranose cycles and, as a result, the evolution of CO2 by a factor of 2-2.5.

  7. Hydroxyl radical induced degradation of salicylates in aerated aqueous solution

    Science.gov (United States)

    Szabó, László; Tóth, Tünde; Homlok, Renáta; Rácz, Gergely; Takács, Erzsébet; Wojnárovits, László

    2014-04-01

    Ionizing radiation induced degradation of acetylsalicylic acid, its hydrolysis product salicylic acid and a salicylic acid derivative 5-sulpho-salicylic acid, was investigated in dilute aqueous solutions by UV-vis spectrophotometry, HPLC separation and diode-array or MS/MS detection, chemical oxygen demand, total organic carbon content and by Vibrio fischeri toxicity measurements. Hydroxyl radicals were shown to degrade these molecules readily, and first degradation products were hydroxylated derivatives in all cases. Due to the by-products, among them hydrogen peroxide, the toxicity first increased and then decreased with the absorbed dose. With prolonged irradiation complete mineralization was achieved.

  8. Improved Low-Temperature Aqueous Synthesis of ZnO Nanorods and Their Use in SERS Detection of 4-ABT and RDX

    Directory of Open Access Journals (Sweden)

    Marcia del R. Balaguera-Gelves

    2013-01-01

    Full Text Available The growth-controlled synthesis of zinc oxide nanorods (ZnO NR in the aqueous phase has been investigated. The rods were grown on ZnO films previously deposited onto Si(100 and indium tin oxide (ITO substrates by RF magnetron sputtering. The formation of the rods took place in the presence of hexamethylenetetramine (HMT as habit-control reagent. The grains in the base ZnO film acted as seeds that promoted the longitudinal growth of the oxide. As-synthesized base films and rods were characterized by X-ray diffraction, scanning electron microscopy (SEM, field emission SEM, optical absorption and photoluminescence spectroscopy techniques. Subsequently, a wet chemistry procedure was performed to achieve ZnO NR growth. This methodology was conducive to the formation of rods of a relatively narrow distribution of diameters (60 - 70 nm with lengths in the 1 - 3 ?m range. Photoluminescence spectra were characterized by a dominant near-band-edge (NBE peak followed by a green luminescence (GL broad band, indicative of higher oxygen vacancy concentration in the ZnO NR grown on ZnO/ITO in comparison with those grown on ZnO/Si(100. A UV process was used for coating the ZnO NR with gold (Au. Au coating on ZnO NR was used to evaluate the detection capability by SERS of different analytes such as: 4-aminobenzenethiol (4-ABT and 1,3,5-trinitroperhydro-1,3,5- triazine (RDX at low levels. A strong SERS Raman spectrum was observed for 4-ABT. A limit of detection (LOD of 1 × 10-8M for 4-ABT was achieved corresponding to a minimum of 5.4 × 105molecules detected under the experimental conditions at excitation wavelength of 785 nm with a sensitivity of the ZnO NR in the range of 1.1 × 10-16g under the laser spot.

  9. Co-administration of ABT-737 and SAHA induces apoptosis, mediated by Noxa upregulation, Bax activation and mitochondrial dysfunction in PTEN-intact malignant human glioma cell lines.

    Science.gov (United States)

    Foster, Kimberly A; Jane, Esther P; Premkumar, Daniel R; Morales, Alejandro; Pollack, Ian F

    2014-12-01

    We previously observed that glioma cells are differentially sensitive to ABT-737 and, when used as a single-agent, this drug failed to induce apoptosis. Identification of therapeutic strategies to enhance the efficacy of the Bcl-2 inhibitor ABT-737 in human glioma is of interest. Histone deacetylation inhibitors (HDACI) are currently being assessed clinically in patients with glioma, as regulation of epigenetic abnormalities is expected to produce pro-apoptotic effects. We hypothesized that co-treatment of glioma with a BH3-mimetic and HDACI may induce cellular death. We assessed the combination of ABT-737 and HDACI SAHA in established and primary cultured glioma cells. We found combination treatment led to significant cellular death when compared to either drug as single agent and demonstrated activation of the caspase cascade. This enhanced apoptosis also appears dependent upon the loss of mitochondrial membrane potential and the release of cytochrome c and AIF into the cytosol. The upregulation of Noxa, truncation of Bid, and activation of Bax caused by this combination were important factors for cell death and the increased levels of Noxa functioned to sequester Mcl-1. This combination was less effective in PTEN-deficient glioma cells. Both genetic and pharmacologic inactivation of the PI3K/Akt signaling pathway sensitized PTEN-deleted glioma cells to the combination. This study demonstrates that antagonizing apoptosis-resistance pathways, such as targeting the Bcl-2 family in combination with epigenetic modifiers, may induce cell death. These findings extend our previous observations that targeting the PI3K/Akt pathway may be additionally necessary to promote apoptosis in cancers lacking PTEN functionality. PMID:25139025

  10. Free radical activity of synthetic vitreous fibers: iron chelation inhibits hydroxyl radical generation by refractory ceramic fiber.

    Science.gov (United States)

    Brown, D M; Fisher, C; Donaldson, K

    1998-04-10

    Synthetic vitreous fibers are in widespread use but the parameters that dictate their carcinogenicity are still a matter of scientific debate. The free radical activities of a panel comprising an asbestos sample and five different respirable synthetic vitreous fiber samples were determined, to address the hypothesis that carcinogenic fibers have greater free radical activity than noncarcinogenic fibers. On the basis of recent inhalation studies, the six samples were divided into three carcinogenic fibers-amphibole asbestos, silicon carbide, and refractory ceramic fiber 1 (designated with the abbreviation RCF 1)-and three noncarcinogenic fibers--man-made vitreous fiber 10 (a glass fiber sample designated with the abbreviation MMVF 10), Code 100/475 glass fiber, and RCF4. All experiments were carried out with equal fiber numbers. Of the two assays of free radical activity used, the plasmid assay of DNA scission showed only amosite asbestos to have free radical activity, while the salicylate assay of hydroxyl activity showed that both amosite asbestos and RCF1 release hydroxyl radicals; silicon carbide fibers had no free radical activity in either of the assays. None of the noncarcinogenic fibers demonstrated free radical activity in either of the assays. The differences in the two assays in demonstrating free radical activity with RCF1 may be due to increased release of Fe from RCF1 under the more acid conditions of the salicylate assay, which was confirmed by the fact that soluble iron caused hydroxylation of salicylate. Presence of an iron chelator inhibited the ability of the RCF1 fibers to cause hydroxylation of salicylate, demonstrating that RCF1 generates hydroxyl radical by Fenton chemical reaction in the same way as amphibole asbestos. PMID:9561968

  11. IRON AND FREE RADICAL OXIDATIONS IN CELL MEMBRANES

    OpenAIRE

    Schafer, Freya Q.; Yue Qian, Steven; Buettner, Garry R.

    2000-01-01

    Brain tissue being rich in polyunsaturated fatty acids, is very susceptible to lipid peroxidation. Iron is well known to be an important initiator of free radical oxidations. We propose that the principal route to iron-mediated lipid peroxidations is via iron-oxygen complexes rather than the reaction of iron with hydrogen peroxide, the Fenton reaction. To test this hypothesis, we enriched leukemia cells (K-562 and L1210 cells) with docosahexaenoic acid (DHA) as a model for brain tissue, incre...

  12. A rapid and sensitive method for determination of veliparib (ABT-888) in human plasma, bone marrow cells and supernatant by using LC/MS/MS

    OpenAIRE

    Reinhardt, Sarah; Zhao, Ming; Mnatsakanyan, Aleksander; Xu, Linping; Ricklis, Rebecca M.; Chen, Alice; Karp, Judith E.; Rudek, Michelle A.

    2009-01-01

    A rapid and sensitive method was developed and validated using a liquid chromatographic method with tandem mass spectrometry detection (LC/MS/MS) for determination of veliparib (ABT-888) in plasma, bone marrow supernatant, and bone marrow cells. Sample preparation involved a single protein precipitation step by the addition of the sample with acetonitrile. Separation of veliparib and the internal standard, A620223.69, was achieved on a Atlantis™ dC18 column (100 × 2.1 mm, 3 ?m) column usi...

  13. Degradation of chlorotriazine pesticides by sulfate radicals and the influence of organic matter.

    Science.gov (United States)

    Lutze, Holger V; Bircher, Stephanie; Rapp, Insa; Kerlin, Nils; Bakkour, Rani; Geisler, Melanie; von Sonntag, Clemens; Schmidt, Torsten C

    2015-02-01

    Atrazine, propazine, and terbuthylazine are chlorotriazine herbicides that have been frequently used in agriculture and thus are potential drinking water contaminants. Hydroxyl radicals produced by advanced oxidation processes can degrade these persistent compounds. These herbicides are also very reactive with sulfate radicals (2.2-3.5 × 10(9) M(-1) s(-1)). However, the dealkylated products of chlorotriazine pesticides are less reactive toward sulfate radicals (e.g., desethyl-desisopropyl-atrazine (DEDIA; 1.5 × 10(8) M(-1) s(-1))). The high reactivity of the herbicides is largely due to the ethyl or isopropyl group. For example, desisopropyl-atrazine (DIA) reacts quickly (k = 2 × 10(9) M(-1) s(-1)), whereas desethyl-atrazine (DEA) reacts more slowly (k = 9.6 × 10(8) M(-1) s(-1)). The tert-butyl group does not have a strong effect on reaction rate, as shown by the similar second order reaction rates between desethyl-terbuthylazine (DET; k = 3.6 × 10(8) M(-1) s(-1)) and DEDIA. Sulfate radicals degrade a significant proportion of atrazine (63%) via dealkylation, in which deethylation significantly dominates over deisopropylation (10:1). Sulfate and hydroxyl radicals react at an equally fast rate with atrazine (k (hydroxyl radical + atrazine) = 3 × 10(9) M(-1) s(-1)). However, sulfate and hydroxyl radicals differ considerably in their reaction rates with humic acids (k (sulfate radical + humic acids) = 6.8 × 10(3) L mgC(-1) s(-1) (mgC = mg carbon); k (hydroxyl radical + humic acids) = 1.4 × 10(4) L mgC(-1) s(-1)). Thus, in the presence of humic acids, atrazine is degraded more efficiently by sulfate radicals than by hydroxyl radicals. PMID:25347797

  14. ABT-737 Synergizes with Bortezomib to Induce Apoptosis, Mediated by Bid Cleavage, Bax Activation, and Mitochondrial Dysfunction in an Akt-Dependent Context in Malignant Human Glioma Cell Lines

    Science.gov (United States)

    Premkumar, Daniel R.; Jane, Esther P.; DiDomenico, Joseph D.; Vukmer, Natalie A.; Agostino, Naomi R.

    2012-01-01

    We observed that glioma cells are differentially sensitive to N-{4-[4-(4?-chloro-biphenyl-2-ylmethyl)-piperazin-1-yl]-benzoyl}-4-(3-dimethylamino-1-phenylsulfanylmethyl-propylamino)-3-nitro-benzenesulfonamide (ABT-737) and administration of ABT-737 at clinically achievable doses failed to induce apoptosis. Although elevated Bcl-2 levels directly correlated with sensitivity to ABT-737, overexpression of Bcl-2 did not influence sensitivity to ABT-737. To understand the molecular basis for variable and relatively modest sensitivity to the Bcl-2 homology domain 3 mimetic drug ABT-737, the abundance of Bcl-2 family members was assayed in a panel of glioma cell lines. Bcl-2 family member proteins, Bcl-xL, Bcl-w, Mcl-1, Bax, Bak, Bid, and Noxa, were found to be expressed ubiquitously at similar levels in all cell lines tested. We then examined the contribution of other apoptosis-resistance pathways to ABT-737 resistance. Bortezomib, an inhibitor of nuclear factor-kappaB (NF-?B), was found to enhance sensitivity of ABT-737 in phosphatase and tensin homolog on chromosome 10 (PTEN)-wild type, but not PTEN-mutated glioma cell lines. We therefore investigated the association between phosphatidylinositol 3-kinase (PI3K)/Akt activation and resistance to the combination of ABT-737 and bortezomib in PTEN-deficient glioma cells. Genetic and pharmacological inhibition of PI3K inhibition sensitized PTEN-deficient glioma cells to bortezomib- and ABT-737-induced apoptosis by increasing cleavage of Bid protein, activation and oligomerization of Bax, and loss of mitochondrial membrane potential. Our data further suggested that PI3K/Akt-dependent protection may occur upstream of the mitochondria. This study demonstrates that interference with multiple apoptosis-resistance signaling nodes, including NF-?B, Akt, and Bcl-2, may be required to induce apoptosis in highly resistant glioma cells, and therapeutic strategies that target the PI3K/Akt pathway may have a selective role for cancers lacking PTEN function. PMID:22393246

  15. ESR study of DNA base cation radicals produced by attack of oxidizing radicals

    International Nuclear Information System (INIS)

    ESR investigations of ?-irradiated aqueous glasses (8 M NaClO4, 12 M LiCl) containing DNA bases and analogues show that oxidizing species produced in the glasses (hydroxyl radicals and Cl2-) at 77 K attack a number of the bases and their analogues after warming to produce ?-cation radicals. Compounds which produce ? cations include thymine, uracil, 3-methyluracil, 6-methyluracil, orotic acid, isoorotic acid, guanine, and adenine. Compounds which are not found to produce ? cations are 1-methylthymine, thymidine, and 1-methyluracil. The overall reaction for formation of the ? cations is as follows: base + OH.(Cl2-) ? OH-(2Cl-) + base cation. A pH and substituent dependence is also noted for the pyrimidines. At pHs where the nitrogen at position 1 is protonated, ?-cation radicals are not formed. In addition, when there are substituents at position 1, ? cations are not found. Analysis of the ESR spectra of the DNA base ? cations for hyperfine splittings and g values were performed by aid of computer simulations. The analyses are in agreement with values found for several DNA base cations produced by photolysis and by direct ? irradiation

  16. Ultraviolet absorption spectra of the 2-phenylethyl radical formed during pulse radiolysis

    International Nuclear Information System (INIS)

    2-Phenylethyl radicals were prepared by the decarboxylation reaction of 3-phenylpropanoic acid with sulfate radical ions formed during the pulse radiolysis of aqueous solutions containing peroxydisulfate ions. The ultraviolet absorption spectrum of the transient radicals consisted of a band centred at 309nm with an extinction coefficient of 50001.mol-1cm-1. Attempts were made to form phenylethyl radicals by the electron-attachment dissociation reaction of (2-haloethyl)benzenes. Contrary to literature reports, it was found that the latter reaction does not occur in either cyclohexane, benzene or aqueous solutions of (2-chloroethyl)- and (2-bromoethyl)-benzenes

  17. FREE RADICAL SCAVENGING, IMMUNOMODULATORY ACTIVITY AND CHEMICAL COMPOSITION OF LUFFA ACUTANGULA VAR: AMARA (CUCURBITACEAE) PERICARP

    Scientific Electronic Library Online (English)

    KALASKAR, MOHAN G.; SURANA, SANJAY J..

    2299-23-01

    Full Text Available The Luffa acutangula Var. amara (Cucurbitaceae) is climbing shrub; commonly known as wild ridge gourd. Its aerial parts are used traditionally in diverse health ailments. Four successive extracts of L. amara pericarp (LAP) were evaluated for antioxidant using in vitro for DPPH, ABTS, superoxides rad [...] ical, reducing power and phosphomolybdenum assay. The bioactive ethanol extract was evaluated for immunomodulatory activity by in vivo phagocytosis using carbon clearance and neutrophil adhesion test. The bioactive ethanolic extracts showed potent in vitro antioxidant ability, increased phagocytic index (0.028 ± 0.002), and increased the % neutrophil adhesion (24.63 ± 0.87%). Furthermore, the potent plant phenolics such as gallic acid and p-hydroxybenzoic acid were isolated and identified spectroscopically. The presence of these plant phenolics and like constituents would be responsible for their potent antioxidant and immunomodulatory activity.

  18. Free Radical Scavenging and Antioxidant Activities of Silymarin Components

    Directory of Open Access Journals (Sweden)

    Kevin P. Anthony

    2013-12-01

    Full Text Available Silymarin is an over the counter food supplement that is sold as a liver enhancement and liver protection preparation. It is a major constituent of the seeds of Silybum marianum which is composed of a mixture of seven major components and several minor compounds. The seven major components: taxifolin, silychristin, silydianin, silybin A, silybin B, iso-silybin A and iso-silybin B were isolated and purified from the crude mixture of silymarin using preparative high performance liquid chromatography to determine which were the most effective for liver protection. Free radical scavenging, hydroxyl radical antioxidant capacity, oxygen radical antioxidant capacity, trolox-equivalent antioxidant capacity and total antioxidant capacity antioxidant activities were determined for each of the individual purified components as well as the crude silymarin mixture. Taxifolin was the most effective component for scavenging free radicals in the DPPH assay with an EC50 of 32 µM far more effective than all other components which showed EC50 ranging from 115 to 855 µM. Taxifolin was also found to be the most effective antioxidant in the oxygen radical antioxidant capacity (ORAC assay with a trolox equivalent of 2.43 and the second most effective in the hydroxyl radical antioxidant capacity (HORAC assay with a gallic acid equivalent of 0.57. Other antioxidants assays did not show significant differences between samples.

  19. Study of lipid peroxyl radicals in urea clathrate crystals: Oxygen-17 couplings and rotational averaging

    International Nuclear Information System (INIS)

    This work reports an electron spin resonance investigation of radicals formed after irradiation of a variety of fatty acid esters trapped in urea clathrate structures. Irradiation of saturated fatty acid esters results in carbon-centered radicals at the ?-carbon site, whereas for unsaturated species the expected allylic and bisallylic radicals are found. Exposure of the carbon-centered radicals to oxygen results in their conversion to the corresponding peroxyl radicals. Orientation- and temperature-dependence studies show that at room temperature both the lipid carbon centered and peroxyl radicals rotate or oscillate in urea channels about their long axis. The rotational jump mechanism found for peroxyl radicals in this work usually follows the trigonal symmetry of the low-temperature distorted urea host channels. At room temperature the entrapped molecules rotate freely on their long axis, and as a consequence orientation of samples at the magic angle (54.7 degree) gives isotropic couplings. Oxygen-17 labeling of the peroxyl radicals results in the first reported anisotropic oxygen hyperfine couplings for lipid peroxyl radicals

  20. Electron Paramagnetic Resonance Study Of Radicals Produced In L-Glutamine Hydrochloride

    International Nuclear Information System (INIS)

    In this study, electron paramagnetic resonance spectroscopy was used to investigate free radicals formed in gamma irradiated L-glutamine hydrochloride amino acid powders. The free radicals produced in L-glutamine hydrochloride powders were attributed to the CH2CHCOOH radical. The g-values of the radicals and the hyperfine structure constants of the free electron with the environmental protons were determined. The samples were not displayed before they were not irradiated. The free radicals were found stable at room temperature for more than six months. Some spectroscopic properties and suggestions concerning possible structure of the radicals are discussed in this work.The powders were irradiated at room temperature with a 60Co gamma-ray source of 20 kGy. After irradiation, sample was kept in plastic bags at room temperature in the dark. The EPR spectroscopy was carried out in a Varian model X-band E-109C EPR spectrometer at room temperature.

  1. Hydroxyl radicals form in natural sediments - effects on sedimentary organic matter

    Science.gov (United States)

    Skoog, Annelie; Alejandro Arias-Esquivel, Victor

    2010-05-01

    We show that hydroxyl radicals form at the oxic anoxic interface in marine sediments from ferrous iron reacting with hydrogen peroxide in the Fenton reaction. The aggressive nature of hydroxyl radicals makes it likely that they participate in degradation of sedimentary organic matter (SOM). We used terephthalic acid (TPA) to trap the hydroxyl radicals in sediment cores - TPA reacts with hydroxyl radicals to form the highly fluorescent product TPAOH. Results indicated formation of TPAOH at high concentrations at the oxic-anoxic interface. We also subjected SOM to hydroxyl radicals formed by the Fenton reaction, which resulted in changes in fluorescence properties and chemical composition. This is the first study showing formation of hydroxyl radicals and their effect on SOM, which is a previously unknown mechanism in the global carbon cycle.

  2. Endothelin stimulates vascular hydroxyl radical formation: Effect of obesity

    OpenAIRE

    Mundy, A L; De Haas, E.; Bhattacharya, I; Widmer, C C; Kretz, M.; Baumann, K; M. Barton

    2007-01-01

    Reactive oxygen species (ROS) and endothelin-1 (ET-1) contribute to vascular pathophysiology in obesity. In this context, whether ET-1 modulates hydroxyl radical (*OH) formation and the function of ROS/*OH in obesity is not known. In the present study, formation and function of ROS, including *OH, were investigated in the aorta of lean and leptin-deficient obese ob/ob mice. Hydroxyl radical formation was detected ex vivo using terephthalic acid in intact aortic rings and the involvement of RO...

  3. Radical production in biological systems

    International Nuclear Information System (INIS)

    This paper describes our effort to develop a metric for radiation exposure that is more fundamental than adsorbed dose and upon which a metric for exposure to chemicals could be based. This metric is based on the production of radicals by the two agents. Radicals produced by radiation in biological systems commonly assumed to be the same as those produced in water despite the presence of a variety of complex molecules. This may explain why the extensive efforts to describe the relationship between energy deposition (track structure) and molecular damage to DNA, based on the spectrum of radicals produced, have not been successful in explaining simple biological effects such as cell killing. Current models assume that DNA and its basic elements are immersed in water-like media and only model the production and diffusion of water-based radicals and their interaction with DNA structures; these models lack the cross sections associated with each macro-component of DNA and only treat water-based radicals. It has been found that such models are not realistic because DNA is not immersed in pure water. A computer code capable of simulating electron tracks, low-energy electrons, energy deposition in small molecules, and radical production and diffusion in water like media has been developed. This code is still in at a primitive stage and development is continuing. It is being used to study radical production by radiation, and radical diffusion and interactions in simple molecular systems following their production. We are extending the code to radical production by chemicals to complement our PBPK modeling efforts. It therefore has been developed primarily for use with radionuclides that are in biological materials, and not for radiation fields

  4. Radical scavenging and antioxidant effects of Matricaria chamomilla polyphenolic-polysaccharide conjugates.

    Science.gov (United States)

    Kolodziejczyk-Czepas, Joanna; Bijak, Michal; Saluk, Joanna; Ponczek, Michal B; Zbikowska, Halina M; Nowak, Pawel; Tsirigotis-Maniecka, Marta; Pawlaczyk, Izabela

    2015-01-01

    Matricaria chamomilla L. (MC), a member of the Asteraceae family, is one of the oldest medicinal plants, widely used worldwide for a variety of healing applications. Its recommendations, derived from both traditional and modern medicine, include numerous disorders such as inflammation, ulcers, wounds, gastrointestinal disorders, stomach ache, pharyngitis, rheumatic pain, as well as the other ailments. This work is focused on another aspect of the biological activity of chamomile polyphenolic-polysaccharide conjugates--their antioxidant properties in the protection of blood plasma components against in vitro oxidative stress. Measurements of DPPH and ABTS radical scavenging indicated considerable anti-free radical action of MC. Pre-incubation of blood plasma with MC considerably diminished the extent of ONOO(-)-induced oxidative modifications such as protein carbonyl groups, SH groups, 3-nitrotyrosine, as well as the formation of lipid hydroperoxides. The analysis of the FRAP assay result shows a considerable increase of ferric reducing ability of blood plasma in the presence of MC. The results obtained in this study indicate that polyphenolic-polysaccharide conjugates isolated from M. chamomilla substances possess antioxidant properties. The M. chamomilla macromolecular glycoconjugates may be useful in the creation of new natural-based medications or dietary supplements, helpful in the prevention and treatment of oxidative stress-mediated disorders. PMID:25285848

  5. Guest Editorial: Processes of Radicalization and De-Radicalization

    Directory of Open Access Journals (Sweden)

    Donatella Della Porta

    2012-05-01

    Full Text Available The study of radicalization and de-radicalization, understood as processes leading towards the increased or decreased use of political violence, is central to the question of how political violence emerges, how it can be prevented, and how it can be contained. The focus section of this issue of the International Journal of Conflict and Violence addresses radicalization and de-radicalization, seeking to develop a more comprehensive understanding of the processes, dynamics, and mechanisms involved and taking an interdisciplinary approach to overcome the fragmentation into separate disciplines and focus areas. Contributions by Pénélope Larzillière, Felix Heiduk, Bill Kissane, Hank Johnston, Christian Davenport and Cyanne Loyle, Veronique Dudouet, and Lasse Lindekilde address repressive settings, legitimacy, institutional aspects, organizational outcomes, and dynamics in Europe, Asia, Africa, and North and South America.

  6. Pulse radiolysis study of chlorpromazine and promazine free radicals in aqueous solution

    International Nuclear Information System (INIS)

    .OH radicals may react with chlorpromazine in four different ways, viz. (i) electron transfer to produce the cation radical, (ii) addition to the sulphur atom followed by acid-catalysed OH- elimination to yield the cation radical, (iii) addition to the aromatic rings to produce cyclohexadienyl type radicals, and (iv) abstraction of hydrogen atoms from the - CH2 - which is in the ? position to the ring nitrogen. Electron transfer and addition to the sulphur atom each account for 40% of the .OH radicals. Similar considerations apply to promazine. The hydrated electron may attach itself to either the sulphur atom in promazine or its aromatic system with equal probability. Addition to the sulphur atom probably leads to immediate cleavage of the carbon-sulphur bond whereas addition to the aromatic system probably produces an anion radical. The lifetime of this anion radical is sufficiently long to enable electron transfer between itself and another promazine molecule to occur to produce the promazine cation radical. With chlorpromazine, the hydrated electron probably reacts solely with the aromatic system to eliminate chloride ions by the end of the reaction. The promazine radical which is produced simultaneously may add on to another chlorpromazine molecule to produce a cyclohexadienyl type radical. (author)

  7. The origins of radical mastectomy.

    Science.gov (United States)

    Sakorafas, George H

    2008-10-01

    William halsted is the 19th century surgeon whose name is most frequently associated with the radical mastectomy procedure; however, this type of surgery actually has been performed since the 16th century. The development of radical mastectomy was a long process, and many surgeons over time have contributed valuable insights and alterations to this fundamental treatment for breast cancer. This procedure may be most commonly associated with Halsted because he promoted a meticulous operative technique, synthesized the best points in the techniques suggested by the most famous surgeons of the 19th century, and provided a scientific basis for the performance of radical mastectomy. PMID:18928961

  8. Observation of OH radicals produced by pulsed discharges on the surface of a liquid

    Energy Technology Data Exchange (ETDEWEB)

    Kanazawa, Seiji; Kawano, Hirokazu; Watanabe, Satoshi; Furuki, Takashi; Akamine, Shuichi; Ichiki, Ryuta; Ohkubo, Toshikazu [Department of Electrical and Electronic Engineering, Oita University, 700 Dannoharu, Oita 870-1192 (Japan); Kocik, Marek; Mizeraczyk, Jerzy, E-mail: skana@cc.oita-u.ac.jp [Szewalski Institute of Fluid Flow Machinery, Polish Academy of Sciences Fiszera 14, 80-952, Gdansk (Poland)

    2011-06-15

    The hydroxyl radical (OH) plays an important role in plasma chemistry at atmospheric pressure. OH radicals have a higher oxidation potential compared with other oxidative species such as free radical O, atomic oxygen, hydroperoxyl radical (HO{sub 2}), hydrogen peroxide(H{sub 2}O{sub 2}) and ozone. In this study, surface discharges on liquids (water and its solutions) were investigated experimentally. A pulsed streamer discharge was generated on the liquid surface using a point-to-plane electrode geometry. The primary generation process of OH radicals is closely related to the streamer propagation, and the subsequent secondary process after the discharge has an influence on the chemical reaction. Taking into account the timescale of these processes, we investigated the behavior of OH radicals using two different diagnostic methods. Time evolution of the ground-state OH radicals above the liquid surface after the discharge was observed by a laser-induced fluorescence (LIF) technique. In order to observe the ground-state OH, an OH [A {sup 2}{Sigma}{sup +}(v' = 1) <- X {sup 2}{Pi}(v'' = 0)] system at 282 nm was used. As the secondary process, a portion of OH radicals diffused from gas phase to the liquid surface and dissolved in the liquid. These dissolved OH radicals were measured by a chemical probe method. Terephthalic acid was used as an OH radical trap and fluorescence of the resulting 2-hydroxyterephthalic acid was measured. This paper directly presents visualization of OH radicals over the liquid surface by means of LIF, and indirectly describes OH radicals dissolved in water by means of a chemical method.

  9. Propargyl radical chemistry: renaissance instigated by metal coordination.

    Science.gov (United States)

    Melikyan, Gagik G

    2015-04-21

    Over the last two decades, radical chemistry of propargyl systems was developed into a potent synthetic field providing access to classes of organic compounds that are otherwise hardly accessible. The levels of diastereoselection thus achieved (up to 100%) are unprecedented for free propargyl radicals, as well as for organic radicals ?-bonded to transition metals. These advances were enabled by the coordination of the triple bond to a Co2(CO)6 core that precluded an acetylene-allene rearrangement, stabilized requisite propargyl cations, created conformational constraints at the carbon-carbon bond formation site, configurationally altered the acetylenic moiety allowing for 1,3-steric induction upon the newly formed stereocenters, increased bulkiness of propargyl triads thus controlling the spatial orientation of converging radicals, and allowed for ?-to-? projection of the reaction site and alteration of the transiency of radical intermediates. In the course of these studies, a number of popular "beliefs" were proven to be untrue. First, cobalt-complexed propargyl cations, which have long been considered to be thermally labile species, were engaged in synthetically meaningful transformation at temperatures as high as 147 °C. Second, in radical dimerization reactions, higher reaction temperatures did not adversely impact the yields and levels of d,l-diastereoselectivity. Third, ?-bonded organometallic radicals, deemed unruly, were effectively controlled with complementary mechanistic tools, thus achieving the highest levels of stereoselectivity (up to 100%) in inter- and intramolecular reactions. Fourth, meso stereoisomers, being thermally labile and kinetically disfavored, were discovered to be major products in intramolecular cyclizations induced by cobaltocene. Fifth, propargyl cations were synthesized in the absence of strong acids, thus increasing the functional tolerance and achieving a long sought after compatibility with acid-sensitive functionalities. A concept of sequestered propargyl radicals was introduced to explain disparity in diastereoselectivity data: heterogeneous reducing agents allegedly produce "free" radicals, while homogeneous reductants generate "sequestered" radicals associated with reductant-derived oxidized species. Among mechanistic tools, a 1,3-steric induction was found to be most efficient for controlling the stereoselectivity of radical reactions (up to 100% d,l). In intramolecular reactions, a d,l-to-meso reversal of stereoselectivity was discovered with zinc being replaced with cobaltocene as a reductant. Among efficient tools for controlling the stereoselectivity in intramolecular cyclizations is a rigidity of the carbon tether that provides for an exclusive formation of d,l-diastereomers. Two novel reactions that belong to a new field of unorthodox organometallic radical chemistry were discovered: the spontaneous conversion of cobalt-complexed propargyl cations to radicals and the THF-mediated process wherein a THF molecule assumes a new role of an initiator in radical reactions. A multistep mechanism involves a THF-induced alteration of propargyl cations that facilitates a redox process between metal clusters. Novel stereoselective methods provide access to topologically and functionally diverse 3,4-diaryl and 3,4-dialkyl-1,5-alkadiynes, 3,4-disubstituted 1,5-cycloalkadiynes (C8-C12), 3,4-dialkoxy-1,5-(cyclo)alkadiynes, and 3,7-diene-1,9-alkadiynes, which can be used in targeted syntheses of organic assemblies of relevance to medicinal chemistry, materials science, and natural product syntheses. Novel mechanistic tools and methodologies for controlling stereoselectivity in radical reactions can be expanded toward new types of ?-bonded unsaturated units (dienes, arenes, diynes, and enynes) and transition metals other than cobalt (Fe, Cr, Mo, W, and Mn). PMID:25746443

  10. Peroxy radical partitioning during the AMMA radical intercomparison exercise

    OpenAIRE

    Andrés-Hernández, M.D.; Stone, D.; Brookes,D.M.; Commane, R.; Reeves, C.E.; Huntrieser, H.; Heard, D. E.; Monks, P. S.; Burrows, J. P.; Schlager, H.; Kartal, D.; Evans, M J; Floquet, C. F. A.; Ingham, T.; J. Methven

    2010-01-01

    Peroxy radicals were measured onboard two scientific aircrafts during the AMMA (African Monsoon Multidisciplinary Analysis) campaign in summer 2006. This paper reports results from the flight on 16 August 2006 during which measurements of HO2 by laser induced fluorescence spectroscopy at low pressure (LIF-FAGE) and total peroxy radicals (RO2*=HO2+?RO2, R= organic chain) by two similar instrum...

  11. Peroxy radical partitioning during the AMMA radical intercomparison exercise

    OpenAIRE

    Andrés-Hernández, M.D.; Stone, D.; Brookes,D.M.; Commane, R.; Reeves, C.E.; Huntrieser, H.; Heard, D. E.; Monks, P. S.; Burrows, J. P.; Schlager, H.; Kartal, D.; Evans, M J; Floquet, C. F. A.; Ingham, T.; J. Methven

    2010-01-01

    Peroxy radicals were measured onboard two scientific aircrafts during the AMMA (African Monsoon Multidisciplinary Analysis) campaign in summer 2006. This paper reports results from the flight on 16 August 2006 during which measurements of HO2 by laser induced fluorescence spectroscopy at low pressure (LIF-FAGE) and total peroxy radicals (RO2* = HO2+?RO2, R = organic chain) by two similar instruments b...

  12. INDO calculations of pyrimidine radicals

    International Nuclear Information System (INIS)

    Theoretical coupling constants of the 5-thymyl radical were calculated by the INDO method. The atomic coordinates of its conformation were obtained from a suggested 'mixed geometrical model'. The calculated results agree satisfactorily with the experimental data. (author)

  13. Reactions of HOCO radicals through hydrogen-atom hopping utilizing clathrate hydrates as an observational matrix.

    Science.gov (United States)

    Oshima, Motoi; Tani, Atsushi; Sugahara, Takeshi; Kitano, Katsuhisa; Ohgaki, Kazunari

    2014-02-28

    The carboxyl (HOCO) radical, which is an important species in atmospheric chemistry and combustion, is an intermediate in the reaction: CO + OH ? CO2 + H and serves as a hydrogen donor to the reaction partners. The cis-HOCO radical, one of the ground-state HOCO radicals, is supposed to be decomposed into CO2 and the hydrogen atom by a tunneling effect. In order to prove the hypothesis, we performed electron spin resonance (ESR) measurements to investigate the decay mechanisms of the ground-state HOCO and DOCO radicals in gamma-ray-irradiated CO2 hydrates, which may hold the radicals stably. The ground-state HOCO and DOCO radicals decayed according to a second-order decay model and transformed into formic acid and CO2. The ratio of the decay rate constants of HOCO and DOCO radicals shows a good agreement with that in the kinetic isotope effect for the hydrogen and deuterium abstraction reactions. These results indicate that they react with another HOCO radical in the adjacent hydrate cage without the tunneling effect. This implies that the ground-state HOCO radicals are not decomposed by the tunneling effect but are decayed through reactions with some atoms, molecules, and/or radicals even in the gas phase. In addition, the hydrogen-atom hopping through the temporary hydrogen bonds between the HOCO radical and CO2 results in a seeming diffusion of the HOCO radicals in the CO2 hydrate; this would be an important concept for the studies of the radical diffusions and the supply of hydrogen atoms in gas, liquid, and solid phases. PMID:24430533

  14. An improved chemical amplifier technique for peroxy radical measurements

    Energy Technology Data Exchange (ETDEWEB)

    Cantrell, C.A.; Shetter, R.E.; Lind, J.A.; McDaniel, A.H.; Calvert, J.G. (National Center for Atmospheric Research, Boulder, CO (United States)); Parrish, D.D.; Fehsenfeld, F.C.; Buhr, M.P.; Trainer, M. (National Oceanic and Atmospheric Administration Aeronomy Lab., Boulder, CO (United States))

    1993-02-20

    The chemical amplifier for atmospheric peroxy radical measurements, first described in the early 1980s has been improved relative to these earlier reports. The details of the instrument and a new radical calibration procedure are discussed as they relate to participation in a field study in the southeastern United States in the summer of 1990. The theoretical behavior of the chemical amplifier is also examined with the use of analytical solutions to the relevant kinetic equations as well as with a numerical model. Several issues of atmospheric relevance are addressed including the response of the instrument to organic peroxy radicals, interferences from PAN and peroxynitric acid, accuracy, precision, and detection limits studied through a number of laboratory and field investigations. Some new findings realized since the summer of 1990 are also included. 44 refs., 16 figs., 2 tabs.

  15. Pharmacological actions of melatonin in oxygen radical pathophysiology.

    Science.gov (United States)

    Reiter, R; Tang, L; Garcia, J J; Muñoz-Hoyos, A

    1997-01-01

    Melatonin, the chief secretory product of the pineal gland, was recently found to be a free radical scavenger and antioxidant. This review briefly summarizes the published reports supporting this conclusion. Melatonin is believed to work via electron donation to directly detoxify free radicals such as the highly toxic hydroxyl radical. Additionally, in both in vitro and in vivo experiments, melatonin has been found to protect cells, tissues and organs against oxidative damage induced by a variety of free radical generating agents and processes, e.g., the carcinogen safrole, lipopolysaccharide, kainic acid, Fenton reagents, potassium cyanide, L-cysteine, excessive exercise, glutathione depletion, carbon tetrachloride, ischemia-reperfusion, MPTP, amyloid beta (25-35 amino acid residue) protein, and ionizing radiation. Melatonin as an antioxidant is effective in protecting nuclear DNA, membrane lipids and possibly cytosolic proteins from oxidative damage. Also, melatonin has been reported to alter the activities of enzymes which improve the total antioxidative defense capacity of the organism, i.e., superoxide dimutase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase, and nitric oxide synthase. Most studies have used pharmacological concentrations or doses of melatonin to protect against free radical damage; in a few studies physiological levels of the indole have been shown to be beneficial against oxidative stress. Melatonin's function as a free radical scavenger and antioxidant is likely assisted by the ease with which it crosses morphophysiological barriers, e.g., the blood-brain barrier, and enters cells and subcellular compartments. Whether the quantity of melatonin produced in vertebrate species is sufficient to significantly influence the total antioxidative defense capacity of the organism remains unknown, but its pharmacological benefits seem assured considering the low toxicity of the molecule. PMID:9194681

  16. Free Radicals and Their Role in Different Clinical Conditions: An Overview

    Directory of Open Access Journals (Sweden)

    Abheri Das Sarma

    2010-04-01

    Full Text Available Free Radicals are molecules with an unpaired electron and are important intermediates in natural processes involving cytotoxicity, control of vascular tone, and neurotransmission. Free radicals are very unstable and react quickly with other compounds, and try to capture the needed electron to gain stability. A chain reaction thus gets started. Once the process is started, it can cascade, and inally results in the disruption of a living cell. Generally, harmful effects of reactive oxygen species on the cell are most often like damage of DNA, oxidations of polydesaturated fatty acids in lipids, oxidations of amino acids in proteins, oxidatively inactivate specific enzymes by oxidation of co-factors. Free radicals cause many human diseases like cancer Alzheimer’s disease, cardiac reperfusion abnormalities, kidney disease, fibrosis, etc. The free radicals formed in our body are combated by antioxidants that safely interact with free radicals and terminate the chain reaction before vital molecules are damaged. Excessive exercise has been found to increase the free radical level in the body and causes intense damage to the Regular physical exercise enhances the antioxidant defense system and protects against exercise induced free radical damage. Apart from the destructive effects of free radical they are also responsible for some vital actions like destroy the bacteria and other cells of foreign matter, kill cancer cells, turning on and off of genes and fight infection, to keep our brain alert and in focus.

  17. Free radicals from purine nucleosides after hydroxyl radical attack

    International Nuclear Information System (INIS)

    Free radicals from imidazole, caffeine, guanosine, deoxyguanosine, inosine, adenosine, deoxyadenosine, and adenine, as well as ?-D-ribose and ?-D-deoxyribose, were generated by reaction with OH from H2O2--Ti3+ at pH 1.5-2 and studied by ESR, using a computerized, Q-band, fast-flow system. Purine base radicals, plus sugar radicals in nucleosides, were always observed. Prior deuteration of C8 made possible the assignment of the observed 10--15 gauss doublet splitting to the C8 proton in guanine derivatives, and to the C2 proton in adenine derivatives and inosine. Hueckel calculations (and INDO in a few cases) on possible radical species suggest that hydroxyl addition on nitrogens in the purine ring or on C5 may be responsible for the species which are observed. In imidazole, the radical species is a hydroxyl adduct. An anomalous effect of deuteration of CS on the spectrum obtained with caffeine is also reported

  18. High deuteron polarization in trityl radical doped deuterated polystyrene

    International Nuclear Information System (INIS)

    Deuterated polystyrene for polarized solid targets has been prepared by chemical doping with the trityl radical ‘Finland D36’ (AH 110 355 deutero acid form). Thin foils doped with various radical densities have been produced using tetrahydrofuran as solvent. Dynamic nuclear polarization technique has been applied to polarize deuterons in the samples (98%-D) at the temperature range of about 1 K and magnetic fields of 2.5 T and 5.0 T. A maximum deuteron polarization of ?61.5% with a build-up time of 100 min has been achieved at 5.0 T and about 500 mK at a radical density of 1.16×1019 spins/g. -- Highlights: •Deuterated polystyrene has been prepared by chemical doping with the trityl radical. •Thin foils doped with various radical densities have been produced. •Deuterons are polarized in the samples (98%-D) at about 1 K and 2.5 T and 5.0 T. •Maximum D-polarization of ?61.5% with a Tbu of 100 min has been achieved

  19. Free Radical Scavenging Activity of Some Nigerian Medicinal Plant Extracts

    Directory of Open Access Journals (Sweden)

    M.O. Sofidiya

    2006-01-01

    Full Text Available The present research evaluates the DPPH radical scavenging, total antioxidant activities, reducing power and total contents of phenolic compounds in methanolic leaf extracts of five Nigerian medicinal plants (Dalbergia saxatilis Hook.f. (Papilionacae, Ekebergia senegalensis A.Juss.(Meliaceae, Hymenocardia acida Tul. (Hymenocardiaceae, Icacina tricantha Oliv. (Icacinaceae and Salacia pallescens Oliv.(Celastraceae. Total phenols were analysed according to the Folin-Ciocalteu method. Each sample under assay condition, showed a dose-dependent effect both on free radical scavenging 1,1-diphenyl-2-picrylhydrazyl radical (DPPH and also on Fe3+ reducing power. The antioxidant activity of the plant extracts with the DPPH radical scavenging and reducing power method, were in the order Hymenocardia> Ekebergia> Salacia> Icacina> Dalbergia. H. acida and E. senegalensis possess very high radical scavenging activity in both assays. Potency of H. acida extract was of the same magnitude as that of reference ?-tocopherol. Total phenols in all the samples expressed as GAE (Gallic Acid Equivalent varied from 1.83 to 15.47mg g-1 of dry plant material. Total antioxidant activities correlated with total phenols (R2 = 0.6640 an indication that 66% of the antioxidant capacity of these extracts results from contribution of phenolic compounds. A linear positive relationship existed between the reducing power and total phenolics of the tested plant extracts (R2 = 0.9564.

  20. Hydroxyl radical formation in batch and continuous flow ultrasonic systems.

    Science.gov (United States)

    Juretic, Hrvoje; Montalbo-Lomboy, Melissa; van Leeuwen, J Hans; Cooper, William J; Grewell, David

    2015-01-01

    The creation of free radicals by ultrasonic cavitation is the main mechanism that leads to chemical degradation of target pollutants and the process is considered an alternative advanced oxidation technology. The goal of this study was to compare the effects of batch and continuous flow ultrasonic systems on the formation of hydroxyl radicals. Ultrasonic batch experiments were conducted in two reactors (small and large) using a standard 20kHz catenoidal titanium horn at varying amplitudes and sonication times. The effect of saturating gas was also investigated by introducing helium and air at 1Lmin(-1) into the larger 100mL reactor. In the continuous flow system, the experiments were conducted with a 20kHz, 3.3kW ultrasonic systems using a titanium "donut" horn at varying volumetric flow rates and amplitudes. Formation of hydroxyl radicals was determined using terephthalic acid dosimetry measurements. At the same energy densities, higher hydroxyl radical concentrations were formed in the batch system than in the continuous flow system. Sonication time appeared to be the main factor that influenced the results in batch and continuous flow systems. The two gases (helium and air) did not increase the hydroxyl radical formation at any amplitude or sonication time tested. PMID:25088186

  1. Photochemical synthesis of simple organic free radicals on simulated planetary surfaces - An ESR study

    Science.gov (United States)

    Tseng, S.-S.; Chang, S.

    1975-01-01

    Electron spin resonance (ESR) spectroscopy provided evidence for formation of hydroxyl radicals during ultraviolet photolysis (254 nm) at -170 C of H2O adsorbed on silica gel or of silica gel alone. The carboxyl radical was observed when CO or CO2 or a mixture of CO and CO2 adsorbed on silica gel at -170 C was irradiated. The ESR signals of these radicals slowly disappeared when the irradiated samples were warmed to room temperature. However, reirradiation of CO or CO2, or the mixture CO and CO2 on silica gel at room temperature then produced a new species, the carbon dioxide anion radical, which slowly decayed and was identical with that produced by direct photolysis of formic acid adsorbed on silica gel. The primary photochemical process may involve formation of hydrogen and hydroxyl radicals. Subsequent reactions of these radicals with adsorbed CO or CO2 or both yield carboxyl radicals, CO2H, the precursors of formic acid. These results confirm the formation of formic acid under simulated Martian conditions and provide a mechanistic basis for gauging the potential importance of gas-solid photochemistry for chemical evolution on other extraterrestrial bodies, on the primitive earth, and on dust grains in the interstellar medium.

  2. Adrogolide HCl (ABT-431; DAS-431), a prodrug of the dopamine D1 receptor agonist, A-86929: preclinical pharmacology and clinical data.

    Science.gov (United States)

    Giardina, W J; Williams, M

    2001-01-01

    Adrogolide (ABT-431; DAS-431) is a chemically stable prodrug that is converted rapidly (animal abuse liability studies indicate that adrogolide is unlikely to have abuse potential in man. Adrogolide has also been reported to reverse haloperidol-induced cognitive deficits in monkeys, suggesting that it may be an effective treatment for the cognitive dysfunction associated with aging and disease. Adrogolide undergoes a high hepatic "first-pass" metabolism in man after oral dosing and, as a result, has a low oral bioavailability (approximately 4%). This limitation may potentially be circumvented by oral inhalation formulations for intrapulmonary delivery that greatly increase the bioavailability of adrogolide. As the first full dopamine D1 receptor agonist to show efficacy in PD patients and to reduce the craving and subjective effects of cocaine in cocaine abusers, adrogolide represents an important tool in understanding the pharmacotherapeutic potential of dopamine D1 receptor agonists. PMID:11607045

  3. The role of free radicals in cold injuries

    Science.gov (United States)

    Bhaumik, G.; Srivastava, K. K.; Selvamurthy, W.; Purkayastha, S. S.

    1995-12-01

    Cold injury is a tissue trauma produced by exposure to freezing temperatures and even brief exposure to a severely cold and windy environment. Rewarming of frozen tissue is associated with blood reperfusion and the simultaneous generation of free oxygen radicals. In this review is discussed the current understanding of the mechanism of action of free oxygen radicals as related to cold injury during rewarming. Decreased energy stores during ischaemia lead to the accumulation of adenine nucleotides and liberation of free fatty acids due to the breakdown of lipid membranes. On rewarming, free fatty acids are metabolized via cyclo-oxygenase and adenine nucleotides are metabolized via the xanthine oxidase pathway. These may be the source of free oxygen radicals. Leukocytes may also play a major role in the pathogenesis of cold injury. Oxygen radical scavengers, such as superoxide dismutase and catalase, may help to reduce the cold induced injury but their action is limited due to the inability readily to cross the plasma membrane. Lipid soluble antioxidants are likely to be more effective scavengers because of their presence in membranes where peroxidative reactions can be arrested.

  4. Glutathione peroxidase: effect of superoxide, hydroxyl and bromine free radicals on enzyme activity

    International Nuclear Information System (INIS)

    Glutathione peroxidase, isolated from human blood, was irradiated in aqueous solutions with 0.2 ?s pulses of electrons from a 4MeV linear accelerator. Solvated electrons were scavenged by nitrous oxide, leaving OH as the principal radical present. A comparison was made of enzyme inactivation following irradiation in the presence of superoxide radicals (formate ions + N20/02) and bromine radicals (bromide ions + N20). Dose-response curves showed that superoxide radicals were much less effective than hydroxyl radicals in inactivating the enzyme, whereas irradiation in the presence of excess bromide ions greatly increased the inactivation. Irradiation in the presence of both bromide and formate ions indicated that there is competition between these two ions for hydroxyl radicals, with the resulting formate radical being unreactive but the bromine radical highly damaging towards the active site. The results suggest that since bromine radicals are selective in their reaction with amino acids, one or more of these sites must be essential for the enzyme's activity. (UK)

  5. Peroxy radical partitioning during the AMMA radical intercomparison exercise

    Directory of Open Access Journals (Sweden)

    M. D. Andrés-Hernández

    2010-04-01

    Full Text Available Peroxy radicals were measured onboard two scientific aircrafts during the AMMA (African Monsoon Multidisciplinary Analysis campaign in summer 2006. This paper reports results from the flight on 16 August 2006 during which measurements of HO2 by laser induced fluorescence spectroscopy at low pressure (LIF-FAGE and total peroxy radicals (RO2*=HO2+?RO2, R= organic chain by two similar instruments based on the peroxy radical chemical amplification (PerCA technique were subject of a blind intercomparison. The German DLR-Falcon and the British FAAM-BAe-146 flew wing tip to wing tip for about 30 min making concurrent measurements on 2 horizontal level runs at 697 and 485 hPa over the same geographical area in Burkina Faso. A full set of supporting measurements comprising photolysis frequencies, and relevant trace gases like CO, NO, NO2, NOy, O3 and a wider range of VOCs were collected simultaneously.

    Results are discussed on the basis of the characteristics and limitations of the different instruments used. Generally, no data bias are identified and the RO2* data available agree quite reasonably within the instrumental errors. The [RO2*]/[HO2] ratios, which vary between 1:1 and 3:1, as well as the peroxy radical variability, concur with variations in photolysis rates and in other potential radical precursors. Model results provide additional information about dominant radical formation and loss processes.

  6. Recent advances of transition-metal catalyzed radical oxidative cross-couplings.

    Science.gov (United States)

    Liu, Chao; Liu, Dong; Lei, Aiwen

    2014-12-16

    CONSPECTUS: Oxidative cross-coupling reactions between two nucleophiles are a powerful synthetic strategy to synthesize various kinds of functional molecules. Along with the development of transition-metal-catalyzed oxidative cross-coupling reactions, chemists are applying more and more first-row transition metal salts (Fe, Co, etc.) as catalysts. Since first-row transition metals often can go through multiple chemical valence changes, those oxidative cross-couplings can involve single electron transfer processes. In the meantime, chemists have developed diverse mechanistic hypotheses of these types of reactions. However, none of these hypotheses have led to conclusive reaction pathways until now. From studying both our own work and that of others in this field, we believe that radical oxidative cross-coupling reactions can be classified into four models based on the final bond formations. In this Account, we categorize and summarize these models. In model I, one of the starting nucleophiles initially loses one electron to generate its corresponding radical under oxidative conditions. Then, bond formations between this radical and another nucleophile create a new radical, [Nu(1)-Nu(2)](•), followed by a further radical oxidation step to generate the cross-coupling product. The radical oxidative alkenylation with olefin, radical oxidative arylative-annulation, and radical oxidative amidation are examples of this model. In model II, one of the starting nucleophiles loses its two electrons via two steps of single-electron-transfer to generate an electrophilic intermediate, followed by a direct bond formation with the other nucleophile. For example, the oxidative C-O coupling of benzylic sp(3) C-H bonds with carboxylic acids and oxidative C-N coupling of aldehydes with amides are members of this model group. For model III, both nucleophiles are oxidized to their corresponding radicals. Then, the radicals combine to form the final coupling product. The dioxygen-involved radical oxidative cross-couplings between sulfinic acids and olefins or alkynes belong to this bond formation model. Lastly, in model IV, one nucleophile loses two electrons to generate an electrophilic intermediate, while the other nucleophile loses one electron to generate a radical. Then, a bond forms between the cation and the radical to generate a cationic radical, followed by a one-electron reduction to afford the final coupling product. The oxidative coupling between arylboronic acids and simple ethers was classified in this model. At the current stage, there are only a few examples presented for models III and IV, but they represent two types of potentially important transformations. More and more examples of these two models will be developed in the future. PMID:25364854

  7. Efficient scavenging of ?-carotene radical cations by antiinflammatory salicylates

    DEFF Research Database (Denmark)

    Cheng, Hong; Liang, Ran

    2014-01-01

    The radical cation generated during photobleaching of ?-carotene is scavenged efficiently by the anion of methyl salicylate from wintergreen oil in a second-order reaction approaching the diffusion limit with k = 3.2 × 10 L mol s in 9:1 v/v chloroform-methanol at 23 °C, less efficiently by the anion of salicylic acid with 2.2 × 10 L mol s, but still of possible importance for light-exposed tissue. Surprisingly, acetylsalicylate, the aspirin anion, reacts with an intermediate rate in a reaction assigned to the anion of the mixed acetic-salicylic acid anhydride formed through base induced rearrangements. The relative scavenging rate of the ?-carotene radical cation by the three salicylates is supported by DFT-calculations. © 2014 The Royal Society of Chemistry.

  8. Molecular mechanisms induced by the effects of ionizing radiation on nucleic acids: Free radicals in 5-halogenated uracil derivatives after reaction of radiolysis products of water in low-temperature glass

    International Nuclear Information System (INIS)

    This thesis deals with the molecular mechanisms induced by the effects of ionizing radiation on the DNA. The study has been made for the main purpose of clarifying the possible role of the indirect effect, namely the attack of diffusible water radicals, in the process of radiosensitivity enhancement due to the incorporation of bromouracil instead of thymine into the DNA. The results of the experiments can be summarized by the statement that among the reactions studied in the low-temperature glasses, none revealed such a clear difference between uracil and thymine on the one hand, and the halogenated uracils on the other, that this difference could suffice to explain in terms of quality and quantity the observed in-vivo enhancement of radiosensitivity by halogenated uracils. This conclusion is in agreement with the results of radiobiological measurements on phagae and bacteria which in all cases revealed no or only very slight enhancement of the radiosensitivity in the indirect effect subsequent to bromouracil incorporation. (orig./AJ)

  9. Free radical reduction of fericytochrome-C

    International Nuclear Information System (INIS)

    Rate constants have been determined for the reduction of ferricytochrome-c by free radicals. k values for pyridinyl radicals, benzoate adduct radicals, nitrobenzene and nitrobenzoate anion radicals, ?-hydroxy radicals, formyl anion radical, and superoxide radical show no apparent correlation with size, charge, or structure of the reductant. Some k values change as the pH is increased. The methyl viologen radical is the most reactive; 1-methyl nicotinamide, NAD; is reactive; the pentaerythritol radical is unreactive at pH = 7 but moderately reactive at pH = 9; and 02- becomes less reactive with increasing pH. The results indicate that several mechanisms for electron transfer are operative and that conformers of differing reactivity influence the kinetics in alkaline solutions

  10. Evaluation of radical scavenging activity of antioxidants by means of electrogenerated HO radical

    OpenAIRE

    Oliveira, Raquel Santos; Bento, M. Fátima; Geraldo, M. Dulce

    2013-01-01

    Hydroxyl radical is one of the most reactive radicals. The electrochemical generation of hydroxyl radical by oxidation of water can be achieved using different anode materials. The adsorption of HO radicals at the anode surface has a significant effect on their reactivity. Using materials such as BDD, electrogenerated hydroxyl radicals are weekly adsorbed whereas strongly adsorbed radicals are formed at Pt. Although most of the available studies deal with high oxidation power a...

  11. Profile of Maytenus aquifolium action over free radicals and reactive oxygen species / Perfil de ação da Maytenus aquifolium sobre radicais livres e espécies reativas do oxigênio

    Scientific Electronic Library Online (English)

    José Carlos Rebuglio, Vellosa; Vanessa de Frias, Barbosa; Najeh Maissar, Khalil; Vânia Aparecida de Freitas Formenton Macedo dos, Santos; Maysa, Furlan; Iguatemy Lourenço, Brunetti; Olga Maria Mascarenhas de Faria, Oliveira.

    2007-09-01

    Full Text Available Espécies Reativas do Oxigênio (ERO) e radicais livres têm tido implicações na iniciação e evolução de muitas doenças ou nas causas das mesmas em organismos vivos; há portanto, necessidade contínua por moléculas antioxidantes para inativar ERO/radicais livres. Estudos sobre extratos brutos de plantas [...] têm demonstrado suas ações antioxidante e seqüestradora de radicais livres. Espécies do gênero Maytenus são utilizadas, em vários países, como medicamentos tradicionais no combate a úlceras gástricas, dispepsia e outras desordens gástricas, bem como por suas propriedades antiinflamatórias. Neste estudo, o extrato bruto etanólico da raiz da Maytenus aquifolium (Celastraceae) foi avaliado quanto à sua habilidade em seqüestrar radicais livres e outras espécies reativas do oxigênio. Os resultados são expressos como porcentagem de inibição das espécies ativas. O extrato foi eficiente contra as espécies estudadas: radical DPPH (inibição alcançada = 35,5 ± 1,3 %), ABTS•+ (IC50 = 0,0036 ± 0,0003 mg/mL), HOCl (IC50 = 0,002 ± 0,0001 mg/mL ), O2•- (inibição alcançada = 36,0 ± 2,1 %), and NO· (inibição alcançada = 18,3 ± 0,4 %). Abstract in english Reactive oxygen species (ROS) and free radical species have been implicated in initiating, accompanying or causing many diseases in living organisms; there is thus, a continual need for antioxidants molecules to inactivate ROS/free radicals. Many studies of plants crude extracts have demonstrated fr [...] ee-radical scavenging and antioxidant action. Maytenus species have long been used, in several countries, as traditional medicines against gastric ulcers, dyspepsia and others gastric problems and for their anti-inflammatory properties. In this study, Maytenus aquifolium (Celastraceae) root bark ethanol extract was assessed for its ability to scavenge free radicals and reactive oxygen species. The results were expressed as percentage inhibition of the active species. The extract was efficient against studied reactive species: DPPH radical (obtained inhibition = 35.5 ± 1.3 %), ABTS•+ (IC50 = 0.0036 ± 0.0003 mg/mL), HOCl (IC50 = 0.002 ± 0.0001 mg/mL ), O2•- (obtained inhibition = 36.0 ± 2.1 %), and NO• (obtained inhibition = 18.3 ± 0.4 %).

  12. Mechanism of hydroxyl radical generation from biochar suspensions: Implications to diethyl phthalate degradation.

    Science.gov (United States)

    Fang, Guodong; Zhu, Changyin; Dionysiou, Dionysios D; Gao, Juan; Zhou, Dongmei

    2015-01-01

    This paper investigated hydroxyl radical (OH) generation from biochar suspensions for diethyl phthalate (DEP) degradation in the presence of oxygen. Electron paramagnetic resonance (EPR) coupled with a salicylic acid trapping method were used to detect free radicals in biochar and verify OH generation from biochar suspensions. Free radicals (FRs) in biochar could induce OH generation, and ?12 spins of FRs were consumed to produce one trapped [OH] molecule. The proposed mechanism of OH generation was that FRs in biochar transferred electrons to O2 to produce the superoxide radical anion and hydrogen peroxide, which reacted further with FRs to produce OH. Free radical-quenching studies utilizing superoxide dismutase, catalase, and deferoxamine as scavengers were used to testify this mechanism. Furthermore, OH generated from biochar suspensions could degrade DEP efficiently. These findings of this study provide new insights into the physicochemical properties and environmental implications of biochar. PMID:25461005

  13. ESTIMATION OF HYDROXYL AND HYDROPEROXYL RADICALS CONCENTRATIONS IN THE URBAN ATMOSPHERE OF SANTIAGO

    Scientific Electronic Library Online (English)

    M. Angélica, Rubio; Eduardo, Liss; Guillermo, Villena; Victoria, Caroca; Ernesto, Gramsch; Álvaro, Ruiz.

    2005-06-01

    Full Text Available Photochemical smog episodes are frequent in Santiago of Chile city. We have measured the concentration of the main free radical precursors (formaldehyde, ozone, nitrogen dioxide, peroxyacetyl nitrate and nitrous acid), nitrogen monoxide and the irradiance. Calculations of the rate of OH* production [...] were performed for different periods of the year and at emission (Cerrillos and Estacion Central) and receptor sites (Las Condes). From these data and simple steady state considerations were derived the concentrations of hydroxyl and hydroperoxyl radicals. Daily profiles of both radicals show a noticeable accumulation during early afternoon, the time of most intense oxidants accumulation. During summer time, hydroperoxyl radical concentrations are higher in Las Condes than in Cerrillos. The concentrations calculated for both radicals are higher than those estimated in other cities, suggesting a particularly high photochemical activity in the urban atmosphere of Santiago of Chile

  14. Hydroxyl radical induced cross-linking between phenylalanine and 2-deoxyribose

    International Nuclear Information System (INIS)

    Hydroxy radicals induce cross-linking between phenylalanine (Phe) and 2-deoxyribose (dR) via formation of corresponding free radical intermediates. The cross-linked products were separated and identified by capillary gas chromatography-mass spectrometry. When phenylalanine and 2-deoxyribose radicals were generated in a 1:1 ratio, the predominant interaction was between Phe and dR radicals while the Phe-Phe and dR-dR cross-links were less abundant. The newly discovered cross-linked between 2-deoxyribose and phenylalanine may serve as a model for radiation or free radical induced cross-linking between DNA and proteins and in general between sugar moieties and amino acids

  15. INDO calculations of pyrimidine radicals

    International Nuclear Information System (INIS)

    Theoretical spin-density distributions of the primary radiation products of cytosine have been calculated at INDO level. The atomic coordinates of their conformations have been obtained using a 'mixed geometrical model'. The theoretical values have been compared with those obtained experimentally and also with calculated values given by other authors. The results predict that the molecular skeleton of cytosine probably remains intact after capture or loss of an electron or loss of a hydrogen atom in the formation of the primary radiation products (radical cation and anion and a neutral radical). (author)

  16. VUV Photoionisation of hydrocarbon radicals

    Science.gov (United States)

    Alcaraz, C.; Noller, Bastian; Hemberger, Patrick; Fischer, Ingo; Gans, Bérenger; Boyé-Peronne, Séverine; Douin, Stéphane; Gauyacq, Dolorès; Soldi-Lose, Héloïse; Garcia, Gustavo

    2008-09-01

    Hydrocarbon radicals CxHy are constituents of various planetary atmospheres, in particular Titan, as a result of the methane photochemistry induced by the solar radiation. They contribute to the neutral chemistry, but are also important for the ionosphere through their photoionisation leading to their cations CxHy +. These cations are also produced by ion-molecule reactions starting from the reaction of the primary ions CH4 + and CH3 + which are created in the non-dissociative and dissociative photoionisation of CH4. This work aims at caracterizing the VUV photoionisation of small hydrocarbon radicals as a function of photon energy. The objective is to provide laboratory data for modelers on the spectroscopy, the thermochemistry, and the reactivity of the radicals and their cations. The hydrocarbon radicals are much less caracterized than stable molecules since they have to be produced in situ in the laboratory experiment. We have adapted at Orsay [1-3] a pyrolysis source (Figure 1) well suited to produce cold beams of hydrocarbon radicals to our experimental setups. Available now at Orsay, we have two new sources of VUV radiation, complementary in terms of tunability and resolution, that can be used for these studies. The first one is the DESIRS beamline [4] at the new french synchrotron, SOLEIL. The second one is the VUV laser developped at the Centre Laser de l'Université Paris-Sud (CLUPS) [5]. At SOLEIL, a photoelectron-photoion coincidence spectrometer is used to monitor the photoionisation on a large photon energy range. At the CLUPS, a pulsedfield ionisation (PFI-ZEKE) spectrometer allows studies at higher resolution on selected photon energies. The first results obtained with these new setups will be presented. References [1] Fischer, I., Schussler, T., Deyerl, H.J., Elhanine, M. & Alcaraz, C., Photoionization and dissociative photoionization of the allyl radical, C3H5. Int. J. Mass Spectrom., 261 (2-3), 227-233 (2007) [2] Schüßler, T., Roth, W., Gerber, T., Alcaraz, C. & Fischer, I., The vacuum ultraviolet photochemistry of radicals: C3H3 and C2H5. Phys. Chem. Chem. Phys., 7 (5), 819-825 (2005) [3] Schüßler, T., Deyerl, H. J., Dummler, S., Fischer, I., Alcaraz, C. & Elhanine, M., The vacuum ultraviolet photochemistry of the allyl radical investigated using synchrotron radiation J. Chem. Phys., 118 (20), 9077-80 (2003) [4] DESIRS, http://www.synchrotronsoleil. fr/portal/page/portal/Recherche/LignesLumiere/ DESIRS [5] CLUPS, http://www.clups.u-psud.fr/

  17. Influence of anoxia on the induction of mutations by phenylalanine radicals during ?-irradiation of plasmid DNA in aqueous solution

    International Nuclear Information System (INIS)

    When DNA is irradiated in aqueous solution, most of the damage is inflicted by water-derived radicals. This is called the indirect effect of ionizing radiation. However in whole cells not only the primary formed water radicals play a role, because some cellular compounds form secondary radicals which can also damage DNA. It is known that the amino acid phenylalanine is able to react with water radicals, resulting in the production of secondary phenylalanine radicals which can damage and inactivate DNA. In a previous study the influence of the presence of phenylalanine during ?-irradiation of DNA in aqueous solution under oxic conditions was studied. Under anoxic irradiation conditions different amounts and types of reactive water-derived radicals are formed compared to oxic conditions and also different phenylalanine radicals are formed. Therefore, this study examines the influence of the presence of phenylalanine under anoxic conditions on the ?-radiation-induced mutation spectrum. The results indicate that phenylalanine radicals are damaging to DNA, but less effective compared to primary water radicals. On the mutational level, in the presence of phenylalanine radicals under anoxic conditions, the amount of mutations on G:C base pairs was significantly decreased as compared to oxic conditions. Furthermore, the results of this study indicate that nucleotide excision repair is involved in repair of both inactivating and mutagenic damage induced by phenylalanine radinic damage induced by phenylalanine radicals under anoxic conditions

  18. O conceito de mal radical The concept of radical evil

    Directory of Open Access Journals (Sweden)

    Adriano Correia

    2005-01-01

    Full Text Available A noção de mal radical aparece em Kant no contexto da discussão da religião nos limites da simples razão e busca dar conta da complexa relação entre o respeito pela lei moral e o amor-próprio na definição do móbil para a ação. Na busca por identificar o fundamento da propensão para o mal no homem, Kant se vê diante da dificuldade de ter de articular natureza e liberdade, e ainda que a noção de mal radical possa conservar algumas ambigüidades, permite conceber uma noção de responsabilidade compatível com uma inata propensão para o mal. Neste texto busco explicitar alguns passos fundamentais na construção do conceito por Kant.The concept of radical evil appears in Kant's theory when he discusses the religion in the limits of the mere reason and aims explain the complex relationship between respect for the moral law and the self-love, for establish the motive of the action. By aiming identify the basis of human inclination to evil, Kant is faced with the trouble of have to put nature and freedom in connection. Despite of the concept of radical evil retain some ambiguity, it allows conceive a notion of responsibility suitable to an inherent inclination to evil. In this paper is my purpose to explain some basic moments of Kantian formulation of that notion.

  19. O conceito de mal radical / The concept of radical evil

    Scientific Electronic Library Online (English)

    Adriano, Correia.

    Full Text Available A noção de mal radical aparece em Kant no contexto da discussão da religião nos limites da simples razão e busca dar conta da complexa relação entre o respeito pela lei moral e o amor-próprio na definição do móbil para a ação. Na busca por identificar o fundamento da propensão para o mal no homem, K [...] ant se vê diante da dificuldade de ter de articular natureza e liberdade, e ainda que a noção de mal radical possa conservar algumas ambigüidades, permite conceber uma noção de responsabilidade compatível com uma inata propensão para o mal. Neste texto busco explicitar alguns passos fundamentais na construção do conceito por Kant. Abstract in english The concept of radical evil appears in Kant's theory when he discusses the religion in the limits of the mere reason and aims explain the complex relationship between respect for the moral law and the self-love, for establish the motive of the action. By aiming identify the basis of human inclinatio [...] n to evil, Kant is faced with the trouble of have to put nature and freedom in connection. Despite of the concept of radical evil retain some ambiguity, it allows conceive a notion of responsibility suitable to an inherent inclination to evil. In this paper is my purpose to explain some basic moments of Kantian formulation of that notion.

  20. Electron spin resonance studies on reduction process of nitroxyl spin radicals used in molecular imaging

    International Nuclear Information System (INIS)

    The Electron spin resonance studies on the reduction process of nitroxyl spin probes were carried out for 1mM 14N labeled nitroxyl radicals in pure water and 1 mM concentration of ascorbic acid as a function of time. The electron spin resonance parameters such as signal intensity ratio, line width, g-value, hyperfine coupling constant and rotational correlation time were determined. The half life time was estimated for 1mM 14N labeled nitroxyl radicals in 1 mM concentration of ascorbic acid. The ESR study reveals that the TEMPONE has narrowest line width and fast tumbling motion compared with TEMPO and TEMPOL. From the results, TEMPONE has long half life time and high stability compared with TEMPO and TEMPOL radical. Therefore, this study reveals that the TEMPONE radical can act as a good redox sensitive spin probe for molecular imaging

  1. Pronounced effect of heterogeneous loss of radicals on the kinetics of liquid-phase free-radical chain chemiluminescent reaction

    International Nuclear Information System (INIS)

    Influence of a glass surface on kinetic parameters of chemiluminescent stage of uranium (4) interaction with the air oxygen in perchloric acid aqueous solutions is studied. It is ascertained that considerable reduction of luminescence yield in the presence of a glass is brought about by essential redistribution of radiation and non-radiation reaction courses in favour of the latter one and increase in the share of OH and HO2 radicals destroyed in contact with a solid body surface

  2. The Games Radicals Play: Special Issue on Free Radicals and Radical Ions

    Directory of Open Access Journals (Sweden)

    John C. Walton

    2015-02-01

    Full Text Available Chemistry and Physics have aptly been described as “most excellent children of Intellect and Art” [1]. Both these “children” engage with many playthings, and molecules rank as one of their first favorites, especially radicals, which are amongst the most lively and exciting. Checking out radicals dancing to the music of entropy round their potential energy ballrooms is surely both entertaining and enlightening. Radicals’ old favorite convolutions are noteworthy, but the new styles, modes and arrangements appearing on the scene are even more interesting. Some of these are ephemeral and enjoy only a brief appearance, others are retro-types reappearing in new guises, still others are genuinely new and “go viral” in the scientific world. This Special Issue of Molecules contains the observations and reflections of a select group of chemists and physicists fascinated by this spectacle. It contains an eclectic mix reflecting on new modes and advances as well as on permutations and combinations that revive mature themes. [...

  3. Organic peroxy free radicals as ultimate agents in oxygen toxicity

    International Nuclear Information System (INIS)

    The role of organic peroxy free radicals in the interaction of oxygen with important biomolecules in in vitro radiation damage studies is reviewed. These studies include the reaction of RO2. but not R. or 02-. with NADH, antioxidants, unsaturated fatty acids, anti-inflammatory drugs and amino acids; the effects of 02-. and CCl302. on the survival of bacterio-phage T2 in the absence and presence of several anti-inflammatory drugs; the inactivation of lyzozyme by CCl302-.; the inactivation of alcohol dehydrogenase by RO2. generally but not 02.; and the protection of ADH by antioxidants and superoxide dismutase. (U.K.)

  4. Myeloperoxidase as an effective inhibitor of hydroxyl radical production. Implications for the oxidative reactions of neutrophils.

    OpenAIRE

    Winterbourn, C C

    1986-01-01

    Hydroxyl radicals have been generated from hydrogen peroxide and superoxide (produced with xanthine oxidase), and an iron (EDTA) catalyst, and detected with deoxyribose, or in some cases with benzoate or alpha-keto-gamma-methiolbutyric acid. Purified myeloperoxidase, and neutrophils stimulated with fMet-Leu-Phe and cytochalasin B, strongly inhibited this hydroxyl radical production in a concentration-dependent manner. Supernatants from stimulated cells also inhibited, and inhibition by cells ...

  5. Radical surgery for pilonidal sinus

    OpenAIRE

    Thomson, James P. S.; Lee, Joseph

    1983-01-01

    Pilonidal sinus disease in 72 patients was treated by radical excision and primary wound closure and the results compared with those other currently practised techniques. A number of factors have been examined in an attempt to identify a group of patients in whom the risk of delayed healing is high.

  6. The Other Women: Radicalizing Feminism.

    Science.gov (United States)

    Puigvert, Lidia; Darder, Antonia; Merrill, Barbara; de los Reyes, Eileen; Stromquist, Nelly

    A recent international symposium on radicalizing feminism explored ways of developing a dialogic feminism that emphasizes working in different settings under the common goal of including women who have been invisible in the dominant feminist literature by furthering theories and practices based on the principles of dialogic feminism. The seminar…

  7. Screening of various botanical extracts for antioxidant activity using DPPH free radical method.

    Science.gov (United States)

    Waqas, Muhammad Khurram; Saqib, Najam-Us; Rashid, Saeed-Ur; Shah, Pervaiz Akhtar; Akhtar, Naveed; Murtaza, Ghulam

    2013-01-01

    Aiming at the exploration of herbal use by society, crude extracts of the seeds of some commonly used medicinal plants (Vitis vinifera, Tamarindus indica and Glycin max) were screened for their free radical scavenging properties using ascorbic acid as standard antioxidant. Free radical scavenging activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical. The overall antioxidant activity of grape seeds (Vitis vinifera) was the strongest, followed in descending order by soybean (Glycin max) and tamarind (Tamarindus indica). The seeds extract of Vitis vinifera, Glycin max and Tamarindus indica showed 85.61%, 83.45% and 79.26%, DPPH scavenging activity respectively. PMID:24311867

  8. Generation of OH radicals at palladium oxide nanoparticle modified electrodes, and scavenging by fluorescent probes and antioxidants.

    OpenAIRE

    J Liu; Lagger, G.; Tacchini, P; Girault, H.H.

    2008-01-01

    The reduction of palladium oxide nanoparticles in the presence of hydrogen peroxide or dissolved oxygen gives rise to a catalytic reduction current dependent on the hydrogen peroxide concentration or the oxygen concentration. Using terephthalic acid as an OH radical scavenger yielding the fluorescent 2-hydroxyterephthalic acid, we demonstrate that the catalytic current stems from the freshly exposed palladium metal re-oxidation by OH radicals. A kinetic model is presented to account for thes...

  9. Kinetic Studies of Some Free Radical Reactions Involved in Cloudwater Chemistry.

    Science.gov (United States)

    Waygood, Steven John

    Available from UMI in association with The British Library. The SO_3^-, SO _4^- and SO_5^ - radicals have been proposed as key intermediates in the mechanisms proposed for the oxidation of dissolved SO_2 initiated by both the OH radical and transition metal ions. This study has investigated the reactivity of these radicals in solution using laser flash photolysis and steady-state photolysis techniques. Photolytic precursors for the radicals have been established. Gated diode array spectroscopy has been used to determine the absorption spectra of the radicals. Kinetic spectrophotometric techniques have been employed to investigate the decay of each radical in aqueous solution in the absence of other species. The reactions of the sulphate radical anion, SO_4^-, with other cloudwater constituents, such as ferrous iron, formaldehyde, formic acid and the hydrogen carbonate anion, have also been studied. Where possible, ion chromatography has been used to identify the aqueous-phase reaction products. In addition, it has been proposed that the reaction of OH radicals with hydrated formaldehyde is a major source of tropospheric formic acid, the major acidic component of precipitation at remote sites. This reaction has been studied and a mechanism proposed which accounts for the observed dependence of the rate of oxidation on the oxygen content of the solution. It was necessary to study this reaction before the reaction between the sulphate radical anion and formaldehyde could be rationalized. Using the results of this study, a better characterized mechanism is proposed for the OH-initiated oxidation of dissolved S(IV). When this scheme is used to predict the rate of formation of S(VI) adopting typical cloudwater concentrations, it is shown that the process could be an important route in the acidification of cloudwater. The study of the reaction between SO_4^ - and Fe(II) shows that current cloud chemistry models greatly overpredict the rate of production of Fe(III) by this route and demonstrate that the role of transition metal ions in cloud chemistry is not fully characterized. It has been confirmed that, under atmospheric conditions, formic acid is the only product of the aqueous oxidation of formaldehyde by the OH radical. The SO_4 ^- radical has also been shown to be an oxidant for both formaldehyde and formic acid, but reaction mechanisms which explain all the empirical facts are not obvious.

  10. Radical reactions on semiconductor colloids

    International Nuclear Information System (INIS)

    Corrosion reactions at the semiconductor-electrolyte interface may severely reduce the longevity of a photoelectrochemical cell, yet they may serve a useful purpose in other materials and other energy systems. Photocorrosion of chalcogenides is an example of the former case, which dissolution of iron oxides in reactor cooling systems are an example of the latter situation. The authors report on a mechanistic study of the corrosion of well defined semiconductor colloids using radiation chemistry and photochemistry techniques. Photoinitiated corrosion of sulfide colloids in oxygen containing solutions was studied on CdS and As/sub 2/S/sub 3/ colloids. The latter colloids are composed of amorphous material as revealed by electron diffraction and verified by analysis of their absorption spectra. Nonetheless, this colloid shows strong quantum size effects in spite of its amorphicity. In both cases, conduction band electrons produce O/sub 2/ radical at the particle surface. However, holes in the valance band will eventually generate S/sup -/ radicals at the surface which, in the absence of a repair mechanism by an electron donor, will also proceed to produce O/sub 2//sup -/ radicals. This explains the efficiency of oxygen in the photocorrosion process. Most surprisingly, on As/sub 2/S/sub 3/ colloids (but not on CdS), the O/sub 2//sup -/ radicals provide another corrosion mechanism by hole injection into the colloid. This is equivalent to current doubling previously observeent to current doubling previously observed in a variety of materials. Furthermore, since the holes lead to regeneration of O/sub 2//sup -/ radicals, as mentioned above, a channel for a chain reaction is available in this material. Addition of CdS to the As/sub 2/S/sub 3/ colloids provides a protection mechanism by blocking the O/sub 2//sup -/ reaction

  11. Pulse radiolysis of pyridinecarboxylic acids in aqueous solution

    DEFF Research Database (Denmark)

    Solar, S.; Getoff, N.

    1991-01-01

    The reactivity of OH, e(aq)- and H radicals towards aqueous carboxypyridines: picolinic acid (2-pyridinecarboxylic acid), PA; isonicotinic acid (4-pyridinecarboxylic acid), i-NA; 2,6-pyridinedicarboxylic acid, 2,6-PDCA; and 3,5-pyridinedicarboxylic acid, 3,5-PDCA was investigated in the pH-range 1-13.8. The absorption spectra of the OH-adducts, H-adducts and pyridinyl radicals are given as well as the formation and decay kinetics. In acid (but not in alkaline) solution, the reaction of H-atoms leads to the formation of two distinct products, namely H-adduct and pyridinyl radicals. The yields of pyridinyl radical are: 20% for PA, 75% for i-NA, 60% for 2,6-PDCA and 25% for 3,5-PDCA (a yield of 50% has been found earlier for nicotinic acid, NA).

  12. Transient phenomena in the pulse radiolysis of retinyl polyenes. l. Radical anions

    International Nuclear Information System (INIS)

    The spectra and kinetics of formation and decay of radical anions of a number of retinyl polenes have been studied in methanol and 2-propanol at room temperature, using pulse radiolysis and kinetic spectrophotometry. The bimolecular rate constants for the attachment of solvated electrons, e-/sub MeOH/, to the retinyl polyenes are in the diffusion-controlled limit (8.6 x 109-1.6 x 1010 M-1 s-1). The radical anions of retinol and retinol acetate have their spectral maxima at 370 to 390 nm, and undergo decay very slowly with second-order kinetics. On the other hand, the radical anions of retinal, retinal n-butylamine Schiff base, and retinoic acid/ester have spectral maxima at 430 to 510 nm, and decay by first-order kinetics in methanol with rate constants in the range 1 x 104 - 1 x 106 s-1. The decay rates of radical anions of retinal and retinoic acid/ester become considerably longer on going from methanol to less acidic alcohol, 2-propanol, suggesting that protonation by sovent is the major mode of their decay in protic media. In the case of retinal Schiff base, an additional slow process with bimolecular rate constant 9.0 x 107 M-1 s-1 in methanol is observed for the formation of radical anion and is ascribed to the electron-transfer reaction from the methanol radical, CH2OH. 6 figures

  13. From Radical Translation to Radical Interpretation and Back

    Directory of Open Access Journals (Sweden)

    António Zilhão

    2003-12-01

    Full Text Available Both Quine and Davidson put forth programs of empirical semantics satisfying the conditions that characterize the so-called “standpoint of interpretation.” Quine’s less ambitious program of radical translation rests upon two buttresses: causality and empathy. Davidson’s more ambitious program of radical interpretation replaces causality with truth and empathy with rationality. Although the replacement of causality with intersubjective truth seems to me to be a fully justified move, I nevertheless contend that it is more realistic to develop the work of interpretation drawing upon Quine’s less ambitious requirement of empathy than upon Davidson’s view of human agency as rational agency. In order to substantiate this contention, I present an argument to the effect that Davidson’s characterization of human agency as rational is not compatible with his other requirement that truth should pro-vide the essential link connecting speech with environment and action.

  14. ¿Es sostenible el constructivismo radical? / Is radical constructivism tenable?

    Scientific Electronic Library Online (English)

    Alfredo, Gaete.

    2013-03-01

    Full Text Available En este trabajo intento mostrar que el constructivismo epistemológico radical es un tesis insostenible, no tanto porque los argumentos a favor de dicha tesis sean deficientes sino porque hasta ahora existen problemas cruciales que ningún constructivista parece haber resuelto y que, sin embargo, debe [...] n ser resueltos para poder siquiera formular la tesis en cuestión. También me refiero a una consecuencia que estas consideraciones tienen en educación. Abstract in english In this work I try to show that radical, epistemological constructivism is an untenable thesis. Not so much because the arguments in favor of such a thesis are deficient, but because there are crucial problems that no constructivist seems to have solved and that must be solved in order for it to be [...] possible to even formulate the thesis in question. I also mention a consequence that these considerations have in education.

  15. Radical carbonylations using a continuous microflow system

    Directory of Open Access Journals (Sweden)

    Takahide Fukuyama

    2009-07-01

    Full Text Available Radical-based carbonylation reactions of alkyl halides were conducted in a microflow reactor under pressurized carbon monoxide gas. Good to excellent yields of carbonylated products were obtained via radical formylation, carbonylative cyclization and three-component coupling reactions, using tributyltin hydride or TTMSS as a radical mediator.

  16. Free-radical chemistry of sulfite.

    OpenAIRE

    Neta, P; Huie, R E

    1985-01-01

    The free-radical chemistry of sulfite oxidation is reviewed. Chemical transformations of organic and biological molecules induced by sulfite oxidation are summarized. The kinetics of the free-radical oxidations of sulfite are discussed, as are the kinetics of the reactions of the sulfite-derived radicals SO3 and the peroxy derivative SO5 with organic compounds.

  17. Rate constants and mechanisms of reaction of Cl2- radicals

    International Nuclear Information System (INIS)

    The rate constants for reaction of Cl2- with various organic and inorganic compounds were determined by kinetic spectrophotometric pulse radiolysis. The Cl2- radical can abstract hydrogen from aliphatic compounds with rate constants that vary from 7 x 102M-1s-1 for t-BuOH to 1.9 x 106M-1s-1 for HCO2-. The reaction with olefinic compounds results in Cl atom addition and takes place with generally higher rate constants, ranging from approximately 106M-1s-1 for double bonds deactivated by adjacent cyano or carboxyl groups to approximately 6 x 108M-1s-1 for allyl alcohol and sorbic acid, for example. Addition to an aromatic ring can also take place with kappa 7M-1s-1 but the important reaction of Cl2- with the aromatic compounds is the direct oxidation by electron transfer. Such oxidation is possible when the ring is substituted with OH, OCH3, NH2, and related groups. The cation radical produced from a methoxy substituted compound was identified by both optical and ESR spectra. The cation radicals from hydroxy or amino substituted compounds undergo deprotonation to produce the phenoxyl or anilino radicals. The reaction of Cl2- with inorganic compounds was also found towith inorganic compounds was also found to involve either hydrogen abstraction or one-electron oxidation for the differenr compounds studied. 1 figure, 3 tables

  18. Prostatectomía radical robótica: resultados oncológicos / Radical robot prostatectomy: oncological outcomes

    Scientific Electronic Library Online (English)

    Esequiel, Rodríguez Jr.; Douglas W., Skarecky; Thomas E., Ahlering.

    2007-05-01

    Full Text Available Objetivo: Revisar la literatura actual relacionada con los resultados oncológicos tras prostatectomía radical laparoscópica asistida por robot (PLAR). Métodos: Se realizó una búsqueda sistemática en MEDLINE de los artículos relativos a los resultados oncológicos de la prostatectomía radical laparosc [...] opia asistida por robot. Dos investigadores seleccionaron, por separado, estudios, valoraron su calidad metodológica y extrajeron los datos. Resultados: Los márgenes quirúrgicos positivos en la PLAR son proporcionales a los de las series laparoscópicas y abiertas. La experiencia quirúrgica y el refinamiento de la técnica ayudan a reducir los márgenes positivos. Los resultados de control de PSA a largo plazo (PSA Abstract in english Objectives: To review the current literature on oncologic outcomes following robot-assisted laparoscopic radical prostatectomy. Methods: A systematic MEDLINE search was performed to retrieve articles relating to oncologic outcomes with robot-assisted laparoscopic prostatectomy. Two reviewers indepen [...] dently selected studies, assessed their methodological quality and extracted data. Results: Positive surgical margin rates in RALP are commensurate to contemporary open and standard laparoscopic series. Surgical experience and refinement of technique helped decrease positive margins. Long-term biochemical disease-free survival (PSA

  19. Triphala, an ayurvedic rasayana drug, protects mice against radiation-induced lethality by free-radical scavenging.

    Science.gov (United States)

    Jagetia, Ganesh Chandra; Malagi, Krishna J; Baliga, Manjeshwar Shrinath; Venkatesh, Ponemone; Veruva, Rosi Reddy

    2004-12-01

    The effects of 10 mg/kg of triphala extract (TE) was studied on radiation-induced sickness and mortality in mice exposed to 7-12 Gray (Gy) of gamma-irradiation. Treatment of mice with triphala once daily for 5 consecutive days before irradiation delayed the onset of mortality and reduced the symptoms of radiation sickness when compared with the non-drug double distilled water treated irradiated controls (DDW). Triphala provided protection against both gastrointestinal and hemopoetic death. However, animals of both the TE + irradiation and DDW + irradiation groups did not survive up to 30 days post-irradiation beyond 11 Gy irradiation. The LD50/30 was found to be 8.6 Gy for the DDW + irradiation group and 9.9 Gy for TE + irradiation group. The administration of triphala resulted in an increase in the radiation tolerance by 1.4 Gy, and the dose reduction factor was found to be 1.15. To understand the mechanism of action of triphala, the free radical scavenging activity of the drug was evaluated. Triphala was found to scavenge (.)OH, O(2) (.) 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) diammonium salt (ABTS)(.+) and NO(.) radicals in a dose dependent manner. PMID:15673991

  20. Serum Hydroxyl Radical Scavenging Capacity as Quantified with Iron-Free Hydroxyl Radical Source

    OpenAIRE

    Endo, Nobuyuki; Oowada, Shigeru; Sueishi, Yoshimi; Shimmei, Masashi; Makino, Keisuke; Fujii, Hirotada; Kotake, Yashige

    2009-01-01

    We have developed a simple ESR spin trapping based method for hydroxyl (OH) radical scavenging-capacity determination, using iron-free OH radical source. Instead of the widely used Fenton reaction, a short (typically 5 seconds) in situ UV-photolysis of a dilute hydrogen peroxide aqueous solution was employed to generate reproducible amounts of OH radicals. ESR spin trapping was applied to quantify OH radicals; the decrease in the OH radical level due to the specimen’s scavenging activity was ...

  1. Rate constants for reactions of inorganic radicals in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Ross, A.B.; Neta, P.

    1979-01-01

    Rate constants have been compiled for reactions of various transient inorganic radicals produced by radiolysis or photolysis in aqueous solution. Data are included for the carbonate radical, sulfate radical, phosphate radical, nitrate radical and other nitrogen-, sulfur- and selenium-containing radicals, and the halide and pseudohalide radicals Cl2(-), Br2(-), I2(-), and (SCN)2(-). The radicals react with other inorganic ions, as well as aliphatic, aromatic and heterocyclic compounds.

  2. DNA binding hydroxyl radical probes

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Vicky J.; Konigsfeld, Katie M.; Aguilera, Joe A. [Department of Radiology, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0610 (United States); Milligan, Jamie R., E-mail: jmilligan@ucsd.edu [Department of Radiology, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0610 (United States)

    2012-01-15

    The hydroxyl radical is the primary mediator of DNA damage by the indirect effect of ionizing radiation. It is a powerful oxidizing agent produced by the radiolysis of water and is responsible for a significant fraction of the DNA damage associated with ionizing radiation. There is therefore an interest in the development of sensitive assays for its detection. The hydroxylation of aromatic groups to produce fluorescent products has been used for this purpose. We have examined four different chromophores, which produce fluorescent products when hydroxylated. Of these, the coumarin system suffers from the fewest disadvantages. We have therefore examined its behavior when linked to a cationic peptide ligand designed to bind strongly to DNA. - Highlights: > Examined four aromatic groups as a means to detect hydroxyl radicals by fluorescence. > Coumarin system suffers from the fewest disadvantages. > Characterized its reactivity when linked to a hexa-arginine peptide.

  3. Radical trapping by PBN during reperfusion in rabbit gastric mucosa.

    Science.gov (United States)

    Sonoda, M; Asakuno, G; Matsuki, M; Satomi, A; Ishida, K; Sakagishi, Y

    1993-01-01

    Oxygen free radicals have been considered as a cause of ischemia-reperfusion injury in several organs, but this injury in a stomach, containing acid, may progress to severe damage. Thus, we examined the effect of ischemia-reperfusion and milk-intake on rabbit gastric mucosa. The gastric mucosal blood flow was increased after milk-intake, and gastric rupture was detected. Superoxide dismutase activity measured by an improved nitroblue tetrazolium reduction method and thiobarbituric acid reactive substances in serum is increased during ischemia-reperfusion and milk-intake. By using alpha-phenyl N-tert-butyl nitrone (PBN) as a spin trap and electron paramagnetic resonance (EPR), we detected lipidic radicals from tissue samples in chloroform-methanol solvent only during reperfusion and milk-intake period; no signal was detected before. The EPR signal of spin adducts obtained in the sample after ischemia-reperfusion and milk-intake would be a mixture of peroxyl and alkoxyl radicals from the analysis of coupling constants. PMID:8282223

  4. Radical Prostatectomy Practice in England

    OpenAIRE

    John E McCabe; Hanchanale, Vishwanath S.; Pradip Javlé

    2010-01-01

    PURPOSE: As there is paucity of data on radical prostatectomy (RP) as a primary treatment for patients with localized prostate cancer, we analyzed the trends in the RP practice in England. MATERIALS AND METHODS: This study was carried out on 14 300 patients who underwent RP for carcinoma of the prostate. Database was prepared from hospital episode statistics of the Department of Health in England. National trends in RP practice were summarized as well as volume outcome analysis. RESULTS: Annu...

  5. Radical Stabilization in Dissolved Humates

    Directory of Open Access Journals (Sweden)

    Barbora Bakajová

    2011-11-01

    Full Text Available Quinoid entities, in which quinone and hydroquinone groups equilibrate via a semiquinone radical intermediate, are a common structural feature in humic materials. The electron paramagnetic resonance (EPR signals of these radicals are significantly enhanced in the presence of diamagnetic divalent metal ions such as Mg2+, while monovalent ions do not show the effect. The addition of trivalent ions leads to rapid precipitation, leaving little room for observation. It was noted that the metal ions producing EPR signal enhancement were also underwent effective bridging interactions with humic subunits, forming pseudomicellar structures. Particle growth determined through dynamic light scattering measurements coincided with the onset of EPR signal enhancement, and surface tension measurements further corroborated the coincidence of aggregation. The addition of a chaotrope (urea, which broke up the humic structures, eliminated the EPR signal increases. These observations strongly suggested that bridging interactions by divalent metal ions, and the intramo- lecular aggregation that accompanied it, led to significant stabilization of semiquinone radicals within the humic structure.

  6. Reactions of hydrocarbon radicals and biradicals.

    Science.gov (United States)

    Pilling, Michael J

    2013-05-01

    Experimental measurements of the rate coefficients for several types of gas phase radical reactions are reviewed. They include radical isomerization and dissociation, radical + radical association, and unimolecular reactions of peroxy radicals. Some reactions of methylene in its lowest singlet state are also considered. The links to theories of chemical reaction rates and especially of capture rates for radical + radical reactions are examined. Many of the reactions involve formation of adducts, which can isomerize and dissociate. Such reactions frequently involve energy distributions of the adducts that are far from Boltzmann, and the interpretation of measurements requires the use of master equation techniques. The basis of these methods and the use of matrix diagonalization and eigenvector/eigenvalue analysis to extract phenomenological rate coefficients are discussed. The relevance of the measurements to applications in atmospheric chemistry and, especially, in combustion is briefly considered. PMID:23570237

  7. Inhibition of phosphatidylinositol 3-kinase/AKT signaling by NVP-BKM120 promotes ABT-737-induced toxicity in a caspase-dependent manner through mitochondrial dysfunction and DNA damage response in established and primary cultured glioblastoma cells.

    Science.gov (United States)

    Jane, Esther P; Premkumar, Daniel R; Morales, Alejandro; Foster, Kimberly A; Pollack, Ian F

    2014-07-01

    Identification of therapeutic strategies that might enhance the efficacy of B-cell lymphoma-2 (Bcl-2) inhibitor ABT-737 [N-{4-[4-(4-chloro-biphenyl-2-ylmethyl)-piperazin-1-yl]-benzoyl}-4-(3-dimethylamino-1-phenylsulfanylmethyl-propylamino)-3-nitro-benzenesulfonamide] is of great interest in many cancers, including glioma. Our recent study suggested that Akt is a crucial mediator of apoptosis sensitivity in response to ABT-737 in glioma cell lines. Inhibitors of phosphatidylinositol 3-kinase (PI3K)/Akt are currently being assessed clinically in patients with glioma. Because PI3K/Akt inhibition would be expected to have many proapoptotic effects, we hypothesized that there may be unique synergy between PI3K inhibitors and Bcl-2 homology 3 mimetics. Toward this end, we assessed the combination of the PI3K/Akt inhibitor NVP-BKM120 [5-(2,6-dimorpholinopyrimidin-4-yl)-4-(trifluoromethyl)pyridin-2-amine] and the Bcl-2 family inhibitor ABT-737 in established and primary cultured glioma cells. We found that the combined treatment with these agents led to a significant activation of caspase-8 and -3, PARP, and cell death, irrespective of PTEN status. The enhanced lethality observed with this combination also appears dependent on the loss of mitochondrial membrane potential and release of cytochrome c, smac/DIABLO, and apoptosis-inducing factor to the cytosol. Further study revealed that the upregulation of Noxa, truncation of Bid, and activation of Bax and Bak caused by these inhibitors were the key factors for the synergy. In addition, we demonstrated the release of proapoptotic proteins Bim and Bak from Mcl-1. We found defects in chromosome segregation leading to multinuclear cells and loss of colony-forming ability, suggesting the potential use of NVP-BKM120 as a promising agent to improve the anticancer activities of ABT-737. PMID:24741074

  8. Protonation of the free 2,4,6-triphenylpyranyl radical

    International Nuclear Information System (INIS)

    When dimethylformamide solutions of 2,4,6-triphenylpyranyl radical (obtained from the dimer, which dissociates reversibly in DMFA) and trifluoroacetic acid are mixed under vacuum (10-3 mm Hg), the mixture acquires a green color. The ESR spectra (recorded on a modified RE-1301 radiospectrometer) contain the radical-cation of 2,4,6-triphenyl-4H-pyran. A characteristic feature of the spectrum is the clearly defined doublet character resulting from the significant splitting at the 4H proton. Each component of the doublet consists of seven groups of hfs lines with intensity ratios of 1:4:7:8:7:4:1 (delocalization of the unpaired electron in the phenyl substituent at the p position). In addition, coupling of the unpaired electron with the 3,5 protons of the pyranyl fragment is observed

  9. Molecular Models of Antioxidants and Radicals

    Science.gov (United States)

    This month's featured molecules come from the paper by John M. Berger, Roshniben J. Rana, Hira Javeed, Iqra Javeed, and Sandi L. Schulien (1) describing the use of DPPH to measure antioxidant activity. DPPH was one of the featured molecules in September 2007 (2) and the basics of antioxidant activity were introduced in last month's column (3). In addition, some of the other molecules in the paper are already in the featured molecules collection (4). The remaining structures in the Figure 1 and Table 1 of the paper have been added to the collection. All structures have been optimized at the 6-311G(D,P) level. These molecules suggest a number of possible student activities, some reminiscent of previous columns and some new. (R,R,R)-?-tocopherol is one of the molecules in the mixture that goes by the name vitamin E. These molecules differ in the substituents on the benzene ring and on whether or not there are alternating double bonds in the phytyl tail. In (R,R,R)-?-tocopherol the R's refer to the three chiral carbon atoms in tail while ? refers to the substituents on the ring. (R,R,R)-?-Tocopherol is the form found in nature. An interesting literature problem would be to have students learn more about the vitamin E mixture and the differing antioxidant activity of the various constituents. Additionally they could be asked to explore the difference between the word natural as used by a chemist, and "natural" as used on vitamin E supplements. Can students find regulations governing the use of the term "natural"? Can they suggest alternative legislation, and defend their ideas? If students read about vitamin C they will discover that only L-ascorbic acid is useful in the body. It would be interesting to extend the experiment described in the Berger et al. paper (1) to include D-ascorbic acid. How do the antioxidant abilities of the enantiomers, as determined by reaction with DPPH compare? Is this consistent with the behavior in the body? Why or why not? Berger et al. mention two other stable neutral radicals, TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) and Fremy's salt. In a reversal from the use of stable radicals to measure antioxidant properties, these two molecules have proven to be very versatile oxidation catalysts in organic synthesis, and would make a rich source of research papers for students in undergraduate organic courses.

  10. Nanostructured hybrid hydrogels prepared by a combination of atom transfer radical polymerization and free radical polymerization.

    Science.gov (United States)

    Bencherif, Sidi A; Siegwart, Daniel J; Srinivasan, Abiraman; Horkay, Ferenc; Hollinger, Jeffrey O; Washburn, Newell R; Matyjaszewski, Krzysztof

    2009-10-01

    A new method to prepare nanostructured hybrid hydrogels by incorporating well-defined poly(oligo (ethylene oxide) monomethyl ether methacrylate) (POEO(300)MA) nanogels of sizes 110-120 nm into a larger three-dimensional (3D) matrix was developed for drug delivery scaffolds for tissue engineering applications. Rhodamine B isothiocyanate-labeled dextran (RITC-Dx) or fluorescein isothiocyanate-labeled dextran (FITC-Dx)-loaded POEO(300)MA nanogels with pendant hydroxyl groups were prepared by activators generated electron transfer atom transfer radical polymerization (AGET ATRP) in cyclohexane inverse miniemulsion. Hydroxyl-containing nanogels were functionalized with methacrylated groups to generate photoreactive nanospheres. (1)H NMR spectroscopy confirmed that polymerizable nanogels were successfully incorporated covalently into 3D hyaluronic acid-glycidyl methacrylate (HAGM) hydrogels after free radical photopolymerization (FRP). The introduction of disulfide moieties into the polymerizable groups resulted in a controlled release of nanogels from cross-linked HAGM hydrogels under a reducing environment. The effect of gel hybridization on the macroscopic properties (swelling and mechanics) was studied. It is shown that swelling and nanogel content are independent of scaffold mechanics. In-vitro assays showed the nanostructured hybrid hydrogels were cytocompatible and the GRGDS (Gly-Arg-Gly-Asp-Ser) contained in the nanogel structure promoted cell-substrate interactions within 4 days of incubation. These nanostructured hydrogels have potential as an artificial extracellular matrix (ECM) impermeable to low molecular weight biomolecules and with controlled pharmaceutical release capability. Moreover, the nanogels can control drug or biomolecule delivery, while hyaluronic acid based-hydrogels can act as a macroscopic scaffold for tissue regeneration and regulator for nanogel release. PMID:19592087

  11. Comparison of the radical trapping ability of PBN, S-PPBN and NXY-059.

    Science.gov (United States)

    Maples, K R; Ma, F; Zhang, Y K

    2001-04-01

    The nitrones alpha-phenyl-N-tert-butyl nitrone (PBN), sodium 2-sulfophenyl-N-tert-butyl nitrone (S-PBN) and disodium 2,4-disulfophenyl-N-tert-butyl nitrone (NXY-059) are neuroprotective in a variety of rodent models. The objective of the current studies was to compare the ability of PBN, S-PBN, and NXY-059 to form radical adducts and to prevent salicylate oxidation in an aqueous system. For the electron spin resonance (ESR) studies, hydroxyl radicals were generated with ultraviolet (UV) light and hydrogen peroxide. Secondary radicals were then produced by the addition of methanol, ethanol, isopropanol, dimethylsulfoxide, tetrahydrofuran or 1,4-dioxane. In addition, competition spin trapping studies were performed using PBN-alpha-(13) C and either S-PBN or NXY-059. In the salicylate studies, PBN, S-PBN and NXY-059 were compared to a variety of other antioxidants and reference compounds (cysteine, glutathione, ascorbate, uric acid, Tempo, Trolox, and Tirilizad) for their ability to prevent 2,3- and 2,5-dihydroxybenzoic acid formation induced by hydroxyl radical generating systems. All 3 nitrones trapped carbon- and oxygen-centered radicals to produce ESR-detectable radical adducts. Each nitrone also prevented salicylate oxidation, with PBN being the most effective. The ability of these 3 nitrones to prevent salicylate oxidation resembled that of most of the other compounds tested. PMID:11328677

  12. Development of nitroxide radicals-containing polymer for scavenging reactive oxygen species from cigarette smoke

    Science.gov (United States)

    Yoshitomi, Toru; Kuramochi, Kazuhiro; Binh Vong, Long; Nagasaki, Yukio

    2014-06-01

    We developed a nitroxide radicals-containing polymer (NRP), which is composed of poly(4-methylstyrene) possessing nitroxide radicals as a side chain via amine linkage, to scavenge reactive oxygen species (ROS) from cigarette smoke. In this study, the NRP was coated onto cigarette filters and its ROS-scavenging activity from streaming cigarette smoke was evaluated. The intensity of electron spin resonance signals of the NRP in the filter decreased after exposure to cigarette smoke, indicating consumption of nitroxide radicals. To evaluate the ROS-scavenging activity of the NRP-coated filter, the amount of peroxy radicals in an extract of cigarette smoke was measured using UV-visible spectrophotometry and 1,1-diphenyl-2-picrylhydrazyl (DPPH). The absorbance of DPPH at 517 nm decreased with exposure to cigarette smoke. When NRP-coated filters were used, the decrease in the absorbance of DPPH was prevented. In contrast, both poly[4-(cyclohexylamino)methylstyrene]- and poly(acrylic acid)-coated filters, which have no nitroxide radical, did not show any effect, indicating that the nitroxide radicals in the NRP scavenge the ROS in cigarette smoke. As a result, the extract of cigarette smoke passed through the NRP-coated filter has a lower cellular toxicity than smoke passed through poly[4-(cyclohexylamino)methylstyrene]- and poly(acrylic acid)-coated filters. Accordingly, NRP is a promising material for ROS scavenging from cigarette smoke.

  13. Antioxidant Mechanisms of Polyphenolic Caffeic Acid Oligomers, Constituents of Salvia officinalis

    OpenAIRE

    WOLF BORS; MICHEL CHRISTA; KURT STETTMAIER; LU YINRONG; Yeap, Foo L.

    2004-01-01

    Caffeic acid, rosmarinic acid and oligomers of caffeic acid with multiple catechol groups are all constituents of Salvia officinalis. Their antioxidant potential was investigated with regard to their radical scavenging activity and the stability and structure of the intermediate radicals. Pulse-radiolytic studies revealed very high rate constants with hydroxyl radicals. Evidence from kinetic modeling calculations suggested an unusual complex behavior due to the presence of both O4- and O3-sem...

  14. Online radicalization: the net or the netizen?

    Directory of Open Access Journals (Sweden)

    Femi Richard Omotoyinbo

    2014-10-01

    Full Text Available Purpose - Radicalization has gained some unusual prominence in the academic circles; maintaining a generic existence not only in the political sector. And with the advent of the Information Communication Technology (ICT, radicalization has begun to have some virtual dimension even in the remotest of human communities. This study seeks to mobilize a universal awareness on the collective urgency to oppose Online Radicalization (a radicalization that happens through the internet due to its propensity to engendering conflicts. It also aims at identifying the principal cause of online radicalization and steer a clear course for a practical reversal in the systems of online radicalization.Design/methodology/approach - The study is divided into three primary parts. The general notion of radicalization is the focus of the first part; which is further analysed into the levels of online radicalization with its accompanying developments and segments. The second part utilizes analytic and historical method to pinpoint the principal cause of online radicalization amidst the suspected causal factors (the Net and the Netizen. The final part analytically focuses on the Netizen (a user/citizen of the internet as the primary cause of online radicalization, and how the global community can bring about a corresponding change in the Net by the application of some measures on the Netizen.Findings - By virtue of the analytic plus historical methods employed by this study; it was initially identified that radicalization is basically having two versions which are online and offline. Further emphasis on the online version reveals that its existence is only made possible by the availability of the internet (the Net. Since the Net is a global phenomenon online radicalization is considered to be worldwide: a menace of globalization. However, the study later indicated that the Net is a facilitator and a cause of online radicalization. A view was deduced that the Netizen is of two categories that include the broad category and the jargon category. The Netizen in the former category was later on conceived as the principal cause of online radicalization.Research limitations/implications - The study averred that all attempts/measures to bring about a reversal in the status quo of online radicalization [De-Radicalization measures] should be directly applied to the principal cause, which is the Netizen. Although the content of the de-radicalization measures were not fully provided by this study due to the reason that the contents can best be supplied by almost everyone that has a vivid understanding of online radicalization. The study continues to affirm that the application of the measures of de-radicalization on the Netizen will bring a corresponding ameliorative effect on the Net against its perpetuation of online radicalization.Practical implications - It is important for domain name providers, governments, internet service providers, mass media, NGOs, parents, politicians, religious organisations, schools, teachers, and web hosting companies to collaborate to create practicable contents for a Gradual Online De-Radicalization (G.O.D which will suppress the perturbing rate of Online Radicalization to the minimal. No unit or sector can singly tackle online radicalization effectively. Therefore, measures of De-Radicalization should be governed by international treaties and laws, and there should be credible agents to legislate and execute the laws respectively.Originality and value - This study broadens the possibilities of reducing online radicalization to the barest minimum globally with some novel strategies categorized broadly as Gradual Online De-Radicalization (G.O.D. The analytic methods applied were plausible skills from the realm of Philosophy and Science respectively. Thus, the findings and suggestions of this study are considered reasonable and universally pragmatic.Research type - general review and viewpoint.

  15. ?-Tocopherol impact on oxy-radical induced free radical decomposition of DMSO: Spin trapping EPR and theoretical studies

    Science.gov (United States)

    Jerzykiewicz, Maria; ?wiel?g-Piasecka, Irmina; Witwicki, Maciej; Jezierski, Adam

    2011-05-01

    EPR spin trapping and theoretical methods such as density functional theory (DFT) as well as combined DFT and quadratic configuration interaction approach (DFT/QCISD) were used to identify the radicals produced in the reaction of oxy-radicals and dimethyl sulfoxide (DMSO) in the presence and absence of ?-tocopherol. Additionally, the mixtures of ?-tocopherol with linolenic acid and glyceryl trilinoleate as well as bioglycerols (glycerol fractions from biodiesel production) were tested. ?-Tocopherol inhibited oxidation of the main decomposition product of DMSO, •CH 3 to •OCH 3 but did not prevent the transformation process of N-t-butyl- ?-phenylnitrone (PBN) into 2-methyl-2-nitrosopropane (MNP). Theoretical investigations confirmed the structures of proposed spin adducts and allowed to correlate the EPR parameters observed in the experiment with the spin adducts electronic structure.

  16. A pulse radiolysis study of salicylic acid and 5-sulpho-salicylic acid in aqueous solutions

    International Nuclear Information System (INIS)

    Reactions of H, OH, eaq- and some one-electron oxidants have been studied with salicylic acid and 5-sulpho-salicylic acid in aqueous solutions. Rate constants for the reaction of eaq- with these compounds were of the order of 109dm3mol-1s-1 and this reaction led to the formation of reducing radicals which could transfer electron to methyl viologen. Other one-electron reductants were not able to reduce these compounds. OH radicals reacted with these compounds by addition pathway with very high rate constants (>1010dm3mol-1s-1) while O- radical anions could oxidize these molecules to give phenoxyl type of radicals. Amongst the one-electron oxidants, only N3 radicals and SO4- radicals could oxidize salicylic acid while 5-sulpho-salicylic acid could be oxidized only by SO4- radicals indicating that while one-electron reduction potential for semi-oxidized SA may beo1 for N3? radical), it is more than 1.33V vs. NHE for semi-oxidized SSA species

  17. Free radical kinetics of irradiated durum wheat

    International Nuclear Information System (INIS)

    In the present work, a detailed ESR investigation of characteristic features and kinetic behaviors at three different temperatures of free radicals produced in a species of durum wheat cultivated in Turkey and irradiated at doses of up to 5 kGy by a ? source, is reported. Unirradiated wheat samples exhibit a weak, single-line ESR signal originating from a radical of unknown structure called radical III in this work. Irradiation produces two more radicals identified as hydroxyalkyl (I) and aldehydalkyl (II) radicals beside radical III. The radicals (I, II and III) follow complicated kinetics. Species I and II initially decay very fast after the irradiation followed by slower decay. Radical half-life times depend on whether they were induced in the crystalline or amorphous fractions of the wheat starch. Activation energy values of the radicals were found to follow the order Ea(III)>Ea(II)>Ea(I). ESR parameters of the radical species were determined by simulating experimental spectra recorded following the irradiation. Room temperature dose-response curves and variations of different spectral parameters between 120 and 390 K were also studied

  18. Free radical kinetics of irradiated durum wheat

    Science.gov (United States)

    Korkmaz, M.; Polat, M.

    2000-04-01

    In the present work, a detailed ESR investigation of characteristic features and kinetic behaviors at three different temperatures of free radicals produced in a species of durum wheat cultivated in Turkey and irradiated at doses of up to 5 kGy by a ? source, is reported. Unirradiated wheat samples exhibit a weak, single-line ESR signal originating from a radical of unknown structure called radical III in this work. Irradiation produces two more radicals identified as hydroxyalkyl (I) and aldehydalkyl (II) radicals beside radical III. The radicals (I, II and III) follow complicated kinetics. Species I and II initially decay very fast after the irradiation followed by slower decay. Radical half-life times depend on whether they were induced in the crystalline or amorphous fractions of the wheat starch. Activation energy values of the radicals were found to follow the order Ea(III)> Ea(II)> Ea(I). ESR parameters of the radical species were determined by simulating experimental spectra recorded following the irradiation. Room temperature dose-response curves and variations of different spectral parameters between 120 and 390 K were also studied.

  19. Radical constructivism: Between realism and solipsism

    Science.gov (United States)

    Martínez-Delgado, Alberto

    2002-11-01

    This paper criticizes radical constructivism of the Glasersfeld type, pointing out some contradictions between the declared radical principles and their theoretical and practical development. These contradictions manifest themselves in a frequent oscillation between solipsism and realism, despite constructivist claims to be an anti-realist theory. The paper also points out the contradiction between the relativism of the radical constructivist principles and the constructivist exclusion of other epistemological or educational paradigms. It also disputes the originality and importance of the radical constructivist paradigm, suggesting the idea of an isomorphism between radical constructivist theory and contemplative realism. In addition, some pedagogical and scientific methodological aspects of the radical constructivist model are examined. Although radical constructivism claims to be a rational theory and advocates deductive thinking, it is argued that there is no logical deductive connection between the radical principles of constructivism and the radical constructivist ideas about scientific research and learning. The paper suggests the possibility of an ideological substratum in the construction and hegemonic success of subjective constructivism and, finally, briefly advances an alternative realist model to epistemological and educational radical constructivism.

  20. Interaction of radiation-generated free radicals with collagen and metalloproteins using cesium-137 gamma source

    Science.gov (United States)

    Shieh, James J.; Wierbicki, Eugen

    The interaction of collagen and metalloproteins with radiation-generated radicals has been studied using spectrophotometric, chromatographic, and ESR techniques. The hydroxyl radical (·OH) reacted with and caused polymerization of acid soluble collagen. Similar reactions were also observed in a ferrimyoglobin and cytochrome C system. Insoluble collagen from bovine muscle subjected to radiation is followed by a first-order process for the decay of free radicals, depending on relative humidity of the system. When the samples were irradiated with 3 kGy at 25°C by a Cesium-137 Irradiator, the observed half life (hr) of free radicals in the samples decreased with increase of relative humidity RH: 31% > 69% > 100%. When collagen, previously kept dry or under 31% RH, was irradiated with 3 kGy at 77°K (-196°C), the decay of free radicals reached a plateau with annealing at -120°C or higher. The decay kept decreasing with annealing at -100°C or higher temperature when collagen maintained at 69 and 100% RH was used. It is concluded that the free radicals in moistened collagen from bovine muscle decreased at a higher rate than in dried collagen. This suggests that free radicals may persist for a longer period of time in irradiated dry proteins of food or animal feed than in foods of higher moisture extent.

  1. Study by ESR of free radicals created by irradiation in some organic substances. Application for dosimetry of the measure of free radicals produced in alanine

    International Nuclear Information System (INIS)

    This report complete the results obtained with free radicals created in glycine. The nature and number of these radicals produced by irradiation in cysteine and glutathion have been investigated free radicals generated in alanine have specially been studied. A linear law exists in a large scale of doses between the number of radicals and the absorbed dose. This property in connection with the high stability of these radicals is very interesting for an use of this amino-acid in dosimetry field. The background of non irradiated alanine is a limit for the best sensibility. With 1 g of alanine in powder, it is possible to make ? measurements between 5 rads and 5. 106 rads. For neutrons, the radicals production yield is lower than for ?. By adding paraffin, it is possible to get a larger yield and to realize compacts dosimeters easier for use than alanine in powder. By adjunction of a higher Z constituent (Ca or Ba for example), it would be possible to improve the yield of the dosimeter for ? energy less than 70 keV. (authors)

  2. One-electron reduction of ferriporphyrins and reactions of ferric and ferrous porphyrins with a halothane-derived radical

    International Nuclear Information System (INIS)

    The reduction of ferrideuteroporphyrin by ?-hydroxyisopropyl radicals is investigated in acidic 2-propanol and acidic 2-propanol-water mixtures by means of steady-state and pulse radiolysis. The rate constant of the reaction is much higher (k approx. = 1.3 x 109 M-1s-1) than that reported for neutral solutions emphasizing the effect of the positive charge carried by the ferric porphyrin in acidic solutions (due to protonation of the alkoxide ligand). Competition kinetic experiments using p-nitroacetophenone as a referene solute show that ?-hydroxyisopropyl radicals are readily scavenged by halothane (CF3CHClBr), leading to CF3CHCl radicals. Pulse irradiation of ferriporphyrin solutions containing halothane allows investigation of the reaction of CF3CHCl radicals with either ferric or ferrous prophyrins depending on the halothane concentration. No reaction of CF3CHCl radicals with ferriporphyrin can be detected (k less than or equal to 106 M-1 s-1). On the other hand, a nearly diffusion-controlled reaction is observed between CF3CHCl radicals and ferrous porphyrin leading to the sigma-bonded alkyl complex of the ferric porphyrin (PFe/sup III/CF3CHCl, where CF3CHCl stands for the alkyl anion). These results are discussed with regard to the reactivity of other alkyl radicals. The relevance to biological models of toxicity of hal to biological models of toxicity of halothane (a widely used anesthetic agent) is outlined

  3. Detection of free radicals in gamma-irradiated soybean paste and model system by electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    We have investigated ESR spectra of fermented soybean paste irradiated at 77 K and compared with those of soybean protein isolate and soybean oil. The influences of irradiation dose, moisture content and heating after irradiation on the free radical concentration and species were examined. Four different carbon type free radicals, FR1-FR4, were identified as the product of amino acid decomposition. In the case of FR1, the doublet line arises from the hydrogen atom on the ?-carbon adjacent to the carbonyl free radical. It disappeared at 150 K. FR2 was most abundant and disappeared at 190 K in wet soybean paste (WSP) and at 210 K in dry soybean paste (DSP), respectively. The radical FR4 originated from decarboxylation and deamination of amino acids, which disappeared at 210 K in both WSP and DSP. FR3 was assumed to be formed by the damage of amino acid side chains. The radical ·OH was originated from water molecules, and was not observed in dry system. Sulfur radical was stable even at room temperature observed in both wet and dry systems. Aldehyde radical must be originated from the chemical reactions of enzymatic hydrolysates of soybean

  4. Detection of free radicals in gamma-irradiated soybean paste and model system by electron spin resonance spectroscopy

    Science.gov (United States)

    Lee, Eun-Joo; Volkov, Vitaly I.; Byun, Myung-Woo; Lee, Cherl-Ho

    2002-04-01

    We have investigated ESR spectra of fermented soybean paste irradiated at 77 K and compared with those of soybean protein isolate and soybean oil. The influences of irradiation dose, moisture content and heating after irradiation on the free radical concentration and species were examined. Four different carbon type free radicals, FR1-FR4, were identified as the product of amino acid decomposition. In the case of FR1, the doublet line arises from the hydrogen atom on the ?-carbon adjacent to the carbonyl free radical. It disappeared at 150 K. FR2 was most abundant and disappeared at 190 K in wet soybean paste (WSP) and at 210 K in dry soybean paste (DSP), respectively. The radical FR4 originated from decarboxylation and deamination of amino acids, which disappeared at 210 K in both WSP and DSP. FR3 was assumed to be formed by the damage of amino acid side chains. The radical ·OH was originated from water molecules, and was not observed in dry system. Sulfur radical was stable even at room temperature observed in both wet and dry systems. Aldehyde radical must be originated from the chemical reactions of enzymatic hydrolysates of soybean

  5. Polyphenolic flavanols as scavengers of aqueous phase radicals and as chain-breaking antioxidants.

    Science.gov (United States)

    Salah, N; Miller, N J; Paganga, G; Tijburg, L; Bolwell, G P; Rice-Evans, C

    1995-10-01

    The purpose of this investigation was to establish the relative antioxidant activities in vitro of the flavanolic polyphenols, the catechins, and catechin-gallate esters. The relative antioxidant potentials were measured against radicals generated in the aqueous phase and against propagating lipid peroxyl radicals. The results show that in the aqueous phase their order of effectiveness as radical scavengers is epicatechin gallate (ECG) > epigallocatechin gallate (EGCG) > epigallocatechin (EGC) > gallic acid (GA) > epicatechin congruent to catechin; against propagating lipid peroxyl radical species, epicatechin and catechin are as effective as ECG and EGCG, the least efficacious being EGC and GA. This is consistent with their relative abilities to protect against consumption of LDL alpha-tocopherol. The results are discussed in the context of the most relevant antioxidant constituents of green tea extracts. PMID:7574706

  6. Origin and scope of long-range stabilizing interactions and associated SOMO-HOMO conversion in distonic radical anions.

    Science.gov (United States)

    Gryn'ova, Ganna; Coote, Michelle L

    2013-10-16

    High-level quantum-chemical methods have been used to study the scope and physical origin of the significant long-range stabilizing interactions between nonmutually conjugated anion and radical moieties in SOMO-HOMO converted distonic radical anions. In such species, deprotonation of the acid fragment can stabilize the remote radical by tens of kilojoules, or, analogously, formation of a stable radical (by abstraction or homolytic cleavage reactions) increases the acidity of a remote acid by several pKa units. This stabilization can be broadly classified as a new type of polar effect that originates in Coloumbic interactions but, in contrast to standard polar effects, persists in radicals with no charge-separated (i.e., dipole) resonance contributors, is nondirectional, and hence of extremely broad scope. The stabilization upon deprotonation is largest when a highly delocalized radical is combined with an initially less stable anion (i.e., the conjugate base of a weaker acid), and is negligible for highly localized radicals and/or stable anions. The effect is largest in the gas phase and low-polarity solvents but is quenched in water, where the anion is sufficiently stabilized. These simple rules can be employed to design various switchable compounds able to reversibly release radicals in response to pH for use in, for example, organic synthesis or nitroxide-mediated polymerization. Moreover, given its wide chemical scope, this effect is likely to influence the protonation state of many biological substrates under radical attack and may contribute to enzyme catalysis. PMID:24090128

  7. Side chain chemistry mediates backbone fragmentation in hydrogen deficient peptide radicals.

    Science.gov (United States)

    Sun, Qingyu; Nelson, Hosea; Ly, Tony; Stoltz, Brian M; Julian, Ryan R

    2009-02-01

    A crown ether based, photolabile radical precursor which forms noncovalent complexes with peptides has been prepared. The peptide/precursor complexes can be electrosprayed, isolated in an ion trap, and then subjected to laser photolysis and collision induced dissociation to generate hydrogen deficient peptide radicals. It is demonstrated that these peptide radicals behave very differently from the hydrogen rich peptide radicals generated by electron capture methods. In fact, it is shown that side chain chemistry dictates both the occurrence and relative abundance of backbone fragments that are observed. Fragmentation at aromatic residues occurs preferentially over most other amino acids. The origin of this selectivity relates to the mechanism by which backbone dissociation is initiated. The first step is abstraction of a beta-hydrogen from the side chain, followed by beta-elimination to yield primarily a-type fragment ions. Calculations reveal that those side chains which can easily lose a beta-hydrogen correlate well with experimentally favored sites for backbone fragmentation. In addition, radical mediated side chain losses from the parent peptide are frequently observed. Eleven amino acids exhibit unique mass losses from side chains which positively identify that particular amino acid as part of the parent peptide. Therefore, side chain losses allow one to unambiguously narrow the possible sequences for a parent peptide, which when combined with predictable backbone fragmentation should lead to greatly increased confidence in peptide identification. PMID:19113886

  8. Aromatic-radical oxidation chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Glassman, I.; Brezinsky, K. [Princeton Univ., NJ (United States)

    1993-12-01

    The research effort has focussed on discovering an explanation for the anomalously high CO{sub 2} concentrations observed early in the reaction sequence of the oxidation of cyclopentadiene. To explain this observation, a number of plausible mechanisms have been developed which now await experimental verification. One experimental technique for verifying mechanisms is to probe the reacting system by perturbing the radical concentrations. Two forms of chemical perturbation of the oxidation of cyclopentadiene were begun during this past year--the addition of NO{sub 2} and CO to the reacting mixture.

  9. Laser spectroscopy of hydrocarbon radicals

    Energy Technology Data Exchange (ETDEWEB)

    Chen, P. [Harvard Univ., Cambridge, MA (United States)

    1993-12-01

    The author reports the application of supersonic jet flash pyrolysis to the specific preparation of a range of organic radicals, biradicals, and carbenes in a skimmed molecular beam. Each species was produced cleanly and specifically, with little or no secondary reactions by the thermal dissociation of appropriately designed and synthesized organic precursors. Photoelectron spectra of the three isomeric C{sub 3}H{sub 2} carbenes, ortho-benzyne, and the {alpha},3-dehydrotoluene biradical, were used to establish adiabatic ionization potentials for use in thermochemical determinations.

  10. Iron and iron derived radicals

    International Nuclear Information System (INIS)

    We have discussed some reactions of iron and iron-derived oxygen radicals that may be important in the production or treatment of tissue injury. Our conclusions challenge, to some extent, the usual lines of thought in this field of research. Insofar as they are born out by subsequent developments, the lessons they teach are two: Think fast! Think small! In other words, think of the many fast reactions that can rapidly alter the production and fate of highly reactive intermediates, and when considering the impact of competitive reactions on such species, think how they affect the microenvironment (on the molecular scale) ''seen'' by each reactive molecule. 21 refs., 3 figs., 1 tab

  11. Free radicals trapped in polyethylene matrix

    International Nuclear Information System (INIS)

    The kinetics of the decay of main chain free radicals trapped in polymer matrix in vacuum were investigated. The decay behaviour of alkyl radicals trapped in the lamellar surface of the crystallites of solution grown polyethylene should be different from that of the same radicals trapped in the inner part of the crystallite, and this difference was clearly observed. The analysis of the data of the decay reaction was made, based on three-dimensional diffusion-controlled reaction theory, and reasonable interpretation of the data was made. Alkyl radicals were also observed in an irradiated urea-polyethylene complex and the decay rate of these radicals was very slow in spite of the large mobility. It was concluded that the mechanism of three-dimensional diffusion of the free radicals across the chain may occur in the inner part of the crystallites via hydrogen abstraction reactions. (author)

  12. Biosynthesis of butenoic acid through fatty acid biosynthesis pathway in Escherichia coli.

    Science.gov (United States)

    Liu, Xiping; Yu, Haiying; Jiang, Xu; Ai, Guomin; Yu, Bo; Zhu, Kun

    2015-02-01

    Butenoic acid is a C4 short-chain unsaturated fatty acid mainly used in the preparation of resins, pharmaceuticals, and fine chemicals. However, butenoic acid derived from petroleum is costly and unfriendly to the environment. Here, we report a novel biosynthetic strategy to produce butenoic acid by utilizing the intermediate of fatty acid biosynthesis pathway in engineered Escherichia coli. A thioesterase gene (B. thetaiotaomicron thioesterase (bTE)) from Bacteroides thetaiotaomicron was heterologously expressed in E. coli to specifically convert butenoyl-acyl carrier protein (ACP), a fatty acid biosynthesis intermediate, to butenoic acid. The titer of butenoic acid ranged from 0.07 to 11.4 mg/L in four different E. coli strains with varied expressing vectors. Deletion of endogenous fadD gene (encoding acyl-CoA synthetase) to block fatty acid oxidation improved the butenoic acid production in all strains to some extent. The highest butenoic acid accumulation of 18.7 mg/L was obtained in strain XP-2 (BL21-?fadD/pET28a-bTE). Moreover, partially inhibiting the enoyl-ACP reductase (FabI) of strain XP-2 by triclosan increased butenoic acid production by threefold, and the butenoic acid titer was further increased to 161.4 mg/L by supplying glucose and tryptone in the M9 medium. Fed-batch fermentation of this strain further enhanced butenoic acid production to 4.0 g/L within 48 h. The butenoic acid tolerance assay revealed that this strain could tolerate 15-20 g/L of butenoic acid. PMID:25472435

  13. Hydrogen bonding constrains free radical reaction dynamics at serine and threonine residues in peptides.

    Science.gov (United States)

    Thomas, Daniel A; Sohn, Chang Ho; Gao, Jinshan; Beauchamp, J L

    2014-09-18

    Free radical-initiated peptide sequencing (FRIPS) mass spectrometry derives advantage from the introduction of highly selective low-energy dissociation pathways in target peptides. An acetyl radical, formed at the peptide N-terminus via collisional activation and subsequent dissociation of a covalently attached radical precursor, abstracts a hydrogen atom from diverse sites on the peptide, yielding sequence information through backbone cleavage as well as side-chain loss. Unique free-radical-initiated dissociation pathways observed at serine and threonine residues lead to cleavage of the neighboring N-terminal C?-C or N-C? bond rather than the typical C?-C bond cleavage observed with other amino acids. These reactions were investigated by FRIPS of model peptides of the form AARAAAXAA, where X is the amino acid of interest. In combination with density functional theory (DFT) calculations, the experiments indicate the strong influence of hydrogen bonding at serine or threonine on the observed free radical chemistry. Hydrogen bonding of the side-chain hydroxyl group with a backbone carbonyl oxygen aligns the singly occupied ? orbital on the ?-carbon and the N-C? bond, leading to low-barrier ?-cleavage of the N-C? bond. Interaction with the N-terminal carbonyl favors a hydrogen-atom transfer process to yield stable c and z(•) ions, whereas C-terminal interaction leads to effective cleavage of the C?-C bond through rapid loss of isocyanic acid. Dissociation of the C?-C bond may also occur via water loss followed by ?-cleavage from a nitrogen-centered radical. These competitive dissociation pathways from a single residue illustrate the sensitivity of gas-phase free radical chemistry to subtle factors such as hydrogen bonding that affect the potential energy surface for these low-barrier processes. PMID:24605822

  14. Free-radical-mediated DNA binding.

    OpenAIRE

    O'Brien, P. J.

    1985-01-01

    Free-radical metabolites can be generated metabolically by a one-electron reductase-catalyzed reaction or a "peroxidase" catalyzed oxidation or by photoactivation of a wide variety of aromatic xenobiotics. Radicals may also be generated during lipid peroxidation. Some radicals can react with DNA or bind covalently or noncovalently as a dismutation product or as a dimer, trimer or polymeric product. Modification to the DNA can result in single-strand breaks, loss of template activity, and cros...

  15. Customers as Partners in Radical Service Innovation

    OpenAIRE

    Scupola, Ada; Nicolajsen, Hanne Westh

    2009-01-01

      Purpose- The main purpose of this paper is to investigate customer involvement and related challenges in radical service innovations in engineering consulting services Design/methodology/approach - The paper uses a case study approach and so called rich descriptions to investigate customer involvement, roles and related challenges and conditions in radical service innovations.Findings- One main finding is that customers can engage in radical service innovations in engineering consultancy s...

  16. Towards radical improvement in production systems

    OpenAIRE

    Ga?svaer, Daniel

    2013-01-01

    As the speed of change is increasing, it’s of great importance that manufacturing companies strive to achieve not only incremental improvements, but also radical improvements within their production systems. Thus, more research has to be focused on how to realize radical improvement. In accordance, the objective of the licentiate thesis is to, through theoretical and empirical work, increase the understanding about radical improvement in production and identify what elements need to be cons...

  17. Identity and Islamic Radicalization in Western Europe

    OpenAIRE

    Murshed, S. M.; Pavan, S.

    2009-01-01

    This paper argues that both socio-economic disadvantage and political factors, such as the West’s foreign policy with regard to the Muslim world, along with historical grievances, play a part in the development of Islamic radicalized collective action in Western Europe. We emphasise the role of group identity based individual behaviour in organising collective action within radicalized Muslim groups. Inasmuch as culture plays any role at all in radicalization, it is because individuals feel...

  18. Reorientation dynamics of cyclohexadienyl radicals in zeolites

    International Nuclear Information System (INIS)

    The dynamics of the muonium substituted cyclohexadienyl radical adsorbed on silicalite and NaZSM-5 is investigated by means of avoided level crossing muon spin resonance. The influence of benzene loading on the mobility of the radical is studied. At low loadings the radicals were found to be located on a single adsorption site where they undergo a wobbling type of motion. With increasing loading an additional species adsorbed on a different site is observed

  19. Quantitative determination of atmospheric hydroperoxyl radical

    Science.gov (United States)

    Springston, Stephen R. (Upton, NY); Lloyd, Judith (Westbury, NY); Zheng, Jun (Stony Brook, NY)

    2007-10-23

    A method for the quantitative determination of atmospheric hydroperoxyl radical comprising: (a) contacting a liquid phase atmospheric sample with a chemiluminescent compound which luminesces on contact with hydroperoxyl radical; (b) determining luminescence intensity from the liquid phase atmospheric sample; and (c) comparing said luminescence intensity from the liquid phase atmospheric sample to a standard luminescence intensity for hydroperoxyl radical. An apparatus for automating the method is also included.

  20. Antioxidant and free radical scavenging activity of Spondias pinnata

    Directory of Open Access Journals (Sweden)

    Mandal Nripendranath

    2008-12-01

    Full Text Available Abstract Background Many diseases are associated with oxidative stress caused by free radicals. Current research is directed towards finding naturally-occurring antioxidants of plant origin. The aim of the present study was to evaluate the in vitro antioxidant activities of Spondias pinnata stem bark extract. Methods A 70% methanol extract of Spondias pinnata stem bark was studied in vitro for total antioxidant activity, for scavenging of hydroxyl radicals, superoxide anions, nitric oxide, hydrogen peroxide, peroxynitrite, singlet oxygen and hypochlorous acid, and for iron chelating capacity, reducing power, and phenolic and flavonoid contents. Results The extract showed total antioxidant activity with a trolox equivalent antioxidant concentration (TEAC value of 0.78 ± 0.02. The IC50 values for scavenging of free radicals were 112.18 ± 3.27 ?g/ml, 13.46 ± 0.66 ?g/ml and 24.48 ± 2.31 ?g/ml for hydroxyl, superoxide and nitric oxide, respectively. The IC50 for hydrogen peroxide scavenging was 44.74 ± 25.61 mg/ml. For the peroxynitrite, singlet oxygen and hypochlorous acid scavenging activities the IC50 values were 716.32 ± 32.25 ?g/ml, 58.07 ± 5.36 ?g/ml and 127.99 ± 6.26 ?g/ml, respectively. The extract was found to be a potent iron chelator with IC50 = 66.54 ± 0.84 ?g/ml. The reducing power was increased with increasing amounts of extract. The plant extract (100 mg yielded 91.47 ± 0.004 mg/ml gallic acid-equivalent phenolic content and 350.5 ± 0.004 mg/ml quercetin-equivalent flavonoid content. Conclusion The present study provides evidence that a 70% methanol extract of Spondias pinnata stem bark is a potential source of natural antioxidants.

  1. Anisole nitration during gamma-irradiation of aqueous nitrite and nitrate solutions: Free radical versus ionic mechanisms

    International Nuclear Information System (INIS)

    Radiolytic aromatic nitration mechanisms in the condensed phase are ubiquitous, and especially of interest in atmospheric aerosol chemistry, water treatment by advanced oxidation technologies, and nuclear fuel reprocessing. Here, the radiolytically-induced nitration reactions of anisole, the simplest aryl alkyl ether, were investigated in ?-irradiated acidic nitrate solution, and in neutral nitrate and nitrite solutions. The nitrated anisole product distribution was the same with and without radiation in acidic solution, although more products were formed as a result of irradiation. This suggests that the mechanism of nitration in acidic solution is nitronium ion-induced electrophilic aromatic substitution. The rate of production of nitrated products in neutral nitrate solution was much lower, although the distribution of isomers was similar to that expected for nitronium ion electrophilic nitration. In contrast, the product distribution in neutral nitrite solution approached a statistically random substitution pattern, suggesting a non-electrop