WorldWideScience
1

Synthesis and Verification of Biobased Terephthalic Acid from Furfural  

Science.gov (United States)

Exploiting biomass as an alternative to petrochemicals for the production of commodity plastics is vitally important if we are to become a more sustainable society. Here, we report a synthetic route for the production of terephthalic acid (TPA), the monomer of the widely used thermoplastic polymer poly(ethylene terephthalate) (PET), from the biomass-derived starting material furfural. Biobased furfural was oxidised and dehydrated to give maleic anhydride, which was further reacted with biobased furan to give its Diels-Alder (DA) adduct. The dehydration of the DA adduct gave phthalic anhydride, which was converted via phthalic acid and dipotassium phthalate to TPA. The biobased carbon content of the TPA was measured by accelerator mass spectroscopy and the TPA was found to be made of 100% biobased carbon.

Tachibana, Yuya; Kimura, Saori; Kasuya, Ken-Ichi

2015-02-01

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Mechanochemical synthesis of compounds of terbium and europium with phthalic and terephthalic acids  

International Nuclear Information System (INIS)

Mechanochemical synthesis of Ln2L3·3H2O composition compounds, where Ln = Eu3+, Tb3+, L - phthalic and terephthalic acids is conducted. It is ascertained that the compound yield depends on the molar ratio of reagents, additions, time of mechanical activation. The complex individuality is confirmed by element chemical analysis, IR- and luminescent spectroscopy methods. (author)

3

Synthesis of terephthalic acid via Diels-Alder reactions with ethylene and oxidized variants of 5-hydroxymethylfurfural.  

Science.gov (United States)

Terephthalic acid (PTA), a monomer in the synthesis of polyethylene terephthalate (PET), is obtained by the oxidation of petroleum-derived p-xylene. There is significant interest in the synthesis of renewable, biomass-derived PTA. Here, routes to PTA starting from oxidized products of 5-hydroxymethylfurfural (HMF) that can be produced from biomass are reported. These routes involve Diels-Alder reactions with ethylene and avoid the hydrogenation of HMF to 2,5-dimethylfuran. Oxidized derivatives of HMF are reacted with ethylene over solid Lewis acid catalysts that do not contain strong Brønsted acids to synthesize intermediates of PTA and its equally important diester, dimethyl terephthalate (DMT). The partially oxidized HMF, 5-(hydroxymethyl)furoic acid (HMFA), is reacted with high pressure ethylene over a pure-silica molecular sieve containing framework tin (Sn-Beta) to produce the Diels-Alder dehydration product, 4-(hydroxymethyl)benzoic acid (HMBA), with 31% selectivity at 61% HMFA conversion after 6 h at 190 °C. If HMFA is protected with methanol to form methyl 5-(methoxymethyl)furan-2-carboxylate (MMFC), MMFC can react with ethylene in the presence of Sn-Beta for 2 h to produce methyl 4-(methoxymethyl)benzenecarboxylate (MMBC) with 46% selectivity at 28% MMFC conversion or in the presence of a pure-silica molecular sieve containing framework zirconium (Zr-Beta) for 6 h to produce MMBC with 81% selectivity at 26% MMFC conversion. HMBA and MMBC can then be oxidized to produce PTA and DMT, respectively. When Lewis acid containing mesoporous silica (MCM-41) and amorphous silica, or Brønsted acid containing zeolites (Al-Beta), are used as catalysts, a significant decrease in selectivity/yield of the Diels-Alder dehydration product is observed. PMID:24912153

Pacheco, Joshua J; Davis, Mark E

2014-06-10

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Effects of synthesis conditions on chemical structures and physical properties of copolyesters from lactic acid, ethylene glycol and dimethyl terephthalate  

Directory of Open Access Journals (Sweden)

Full Text Available Lactic acid/ethylene terephthalate copolyesters were synthesized by the standard melt polycondensation of lactic acid (L, ethylene glycol (EG and dimethyl-terephthalate (DMT. Effects of reaction temperatures and types of catalysts on the structures and properties of the copolymers were examined. In addition, feasibility of promoting the copolymerization process by a novel synthesis step of using thermo-stabilizers was investigated. The results show that a reaction temperature of higher than 180°C is necessary to produce copolymers with appreciable molecular weight. However, degradation was observed when the reaction temperature is higher than 220°C. Triphenyl phosphate (TPP shows promising results as a potential thermo-stabilizer to minimize this problem. It was found that Sb2O3 and Tin(II octoate are most effective among 4 types of catalysts employed in this study. 1H-NMR results indicate that copolymers have a random microstructure composed mainly of single L units alternately linked with ET blocks at various sequential lengths. The longer ET sequence in the chain structure leads to the increase in melting temperature of the copolymer. TGA results show that the resulting copolymers possessed greater thermal stability than commercially-available aliphatic PLA, as a result of the inclusion of T (terephthalate units in the chain structure.

2009-07-01

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Synthesis of terephthalic acid via Diels-Alder reactions with ethylene and oxidized variants of 5-hydroxymethylfurfural  

OpenAIRE

Current, plant-based polyethylene terephthalate (PET) is produced from biomass-derived ethylene glycol [the terephthalic acid (PTA) used is not from biomass]. To have a 100% biomass-derived PET, PTA must be produced from biomass. Here, pathways for the production of renewable PTA, using Diels-Alder reactions between ethylene and oxidized derivatives of 5-hydroxymethylfurfural, a biomass-derived chemical, are reported. These pathways are enabled by new catalytic chemistry that may provide rout...

Pacheco, Joshua J.; Davis, Mark E.

2014-01-01

6

Renal handling of terephthalic acid  

International Nuclear Information System (INIS)

By use of the Sperber in vivo chicken preparation method, infusion of radiolabeled terephthalic acid ([14C]TPA) into the renal portal circulation revealed a first-pass excretion of the unchanged compound into the urine. This model was utilized further to characterize the excretory transport of [14C]TPA and provide information on the structural specificity in the secretion of dicarboxylic acids. At an infusion rate of 0.4 nmol/min. 60% of the [14C]TPA which reached the kidney was directly excreted. An infusion rate of 3 or 6 mumol/min resulted in complete removal of [14C]TPA by the kidney. These results indicate that TPA is both actively secreted and actively reabsorbed when infused at 0.4 nmol/min and that active reabsorption is saturated with the infusion of TPA at higher concentrations. The secretory process was saturated with the infusion of TPA at 40 mumol/mn. The excretory transport of TPA was inhibited by the infusion of probenecid, salicylate, and m-hydroxybenzoic acid, indicating that these organic acids share the same organic anion excretory transport process. m-Hydroxybenzoic acid did not alter the simultaneously measured excretory transport of p-aminohippuric acid (PAH), suggesting that there are different systems involved in the secretion of TPA and PAH. The structural specificity for renal secretion of dicarboxylic acids was revealed by the use of o-phthalic acid and m-phthalic acid as possible inhibitors of TPAhthalic acid as possible inhibitors of TPA secretion

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Synthesis and characterizations of degradable aliphatic-aromatic copolyesters from lactic acid, dimethyl terephthalate and diol: Effects of diol type and monomer feed ratio  

Directory of Open Access Journals (Sweden)

Full Text Available Lactic acid-based aliphatic/aromatic copolyesters are synthesized to incorporate the degradability of polylactic acid and good mechanical properties of aromatic species by using polycondensation of lactic acid (LA, dimethyl terephthalate (DMT, and various diols. Effects of diol lengths and comonomer feed ratios on structure and properties of the resulting copolymers are investigated. Three types of diols with different methylene lengths are employed, i.e., ethylene glycol (EG, 1,3-propanediol (PD and 1,4-butanediol (BD. LA/DMT/diol feed ratios of 2:1:2, 1:1:2, and 1:2:4 are used in each diol system. It is found that types of the diols play an important role in the properties of the copolyester, where an increase in diol length results in an increase in the copolymers molecular weight, and a decrease in Tg, Tm and crystallinity, when a constant monomer feed ratio is employed. Monomer feed ratio also has a significant effect on properties of the copolymers, where an increase in the aromatic content leads to formation of copolymers with higher molecular weight, longer aromatic block sequence and high aromatic to aliphatic ratio in the chain structure. These, in turn, lead to an increase in Tg, Tm, crystallinity and thermal stability of the copolymer samples, and a reduction in their solubility.

2010-07-01

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Poly (ethylene terephthalate synthesis with catalysts derived from chrysotile asbestos  

Directory of Open Access Journals (Sweden)

Full Text Available The chrysotile asbestos was converted to the forsterite-type compounds by calcination at 740 and 800ºC (F7-740 and F7-800, which were used as a catalyst for the polycondensation of bis(hydroxyethyl terephthalate affording poly (ethylene terephthalate. The obtained forsterite-type compounds did not show any catalytic activity. However, the products obtained by simply treating them with acetic acid significantly promoted the polymerization that produced a THFinsoluble polymer. It was found that the polymer prepared with the acetic acid-treated F7-740 at 160ºC for 2 h showed a 93% yield and the number average molecular weight of 6.4 × 103. The observed catalytic activity was higher than that for the acetic acid-treated magnesium oxide, as well as the typical polycondensation catalysts, such as magnesium acetate and antimony oxide.

Shigeki Habaue

2010-06-01

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Degradation of terephthalic acid by a newly isolated strain of Arthrobacter sp.0574  

Scientific Electronic Library Online (English)

Full Text Available Terephthalic acid is an important industrial chemical but its production typically generates 3-10 tons of wastewater, which is a significant source of pollution. Although recent research has shown that terephthalic acid can be degraded by physical and chemical methods, these methods are complex and [...] expensive. Microbial degradation of terephthalic acid is a popular alternative because it is environmentally friendly. We isolated a Gram-positive strain capable of growing aerobically on terephthalic acid as the sole carbon and energy source. It was identified as Arthrobacter sp. by 16S rDNA sequencing and its physiological and biochemical characteristics. For terephthalic acid degradation, the optimal temperature of the resting cells was 30 °C, optimal shaking speed was 150 rpm, the most suitable pH was 7.0, and the ability to degrade terephthalic acid was inhibited by concentrations of terephthalic acid above 10 g/L.

Yi-Mei, Zhang; Yao-Qun, Sun; Zhi-Jiang, Wang; Jie, Zhang.

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Synthesis Dibenzyl Terephthalate Through Depolimerization of Poly(ethylene terephthalate as Alternative of Waste Plastics Recycling.  

Directory of Open Access Journals (Sweden)

Full Text Available Synthesis dibenzyl terephathalate were done through PET degradation by refluxing in benzyl alcohol at 145oC temperature for 20, 24, and 28 hours in the presence of zinc acetate catalyst. The result of degradation was purified by recristalization in methanol and then melting point (mp, FTIR, 1H NMR spectra, and TLC spot were determined. The melting point of product degradation for 28 hours was 98-99 oC. Based FTIR spectra known that compunds of product degradation have OH, C=O, C-O, CH, monosubstituted benzene, disubstituted benzene groups, while on 1H NMR spectra showed chemical shift at 8.2 ppm (s, 10 H of monosubtituted benzene, 7.5 ppm (s, 9 H consist of 4 H disubstituted benzene and 5 H of aromatic benzyl alcohol, 5.4 ppm (s, 1 H from OH benzyl alcohol, 4.8 ppm (s, 4 H of methylene, and 2.9 ppm (s, 7 H of other traces. The single spot of TLC plate indicated that product degradation for 28 hours might be a single compund. Based these characterization concluded that compound of product degradation was dibenzyl terephthalate contains benzyl alcohol and other traces.

Dyah Anitasari

2005-04-01

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Sequential pyrolysis of plastic to recover polystyrene, HCl and terephthalic acid  

Science.gov (United States)

A process is described for pyrolyzing plastic waste feed streams containing polyvinyl chloride, polyethylene terephthalate, polystyrene and polyethylene to recover polystyrene, HCl and terephthalic acid comprising: heating the plastic waste feed stream to a first temperature; adding an acid or base catalyst on an oxide or carbonate support; heating the plastic waste feed stream to pyrolyze polyethylene terephthalate and polyvinyl chloride; separating terephthalic acid or HCl; heating to a second temperature to pyrolyze polystyrene; separating styrene; heating the waste feed stream to a third temperature to pyrolyze polyethylene; and separating hydrocarbons. 83 figs.

Evans, R.J.; Chum, H.L.

1995-11-07

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New Titanium-Based Catalysts for the Synthesis of Poly(ethylene terephthalate)  

Energy Technology Data Exchange (ETDEWEB)

Poly(ethylene terephthalate) (PET) is a polymer with relatively low cost and high performance, which is widely used in various applications such as bottles, textile fibers, films and engineering plastics for automobiles and electric industries. Commercial catalysts used for synthesis of PET are in general antimony (Sb) compounds. Antimony(III) oxide, antimony(III) acetate and antimony(III) glycolate are used as a catalyst in 95% of PET manufacturing industries worldwide. The few organoantimony compounds that have been identified in environmental and biological samples are all in the form of methylated Sb-species. The Sb trace element is extremely toxic to mammals, and interferes with embryonic and fetal development, also, carcinogenic to humans. In addition to being found in drinking water, food packaging and soft-drink bottles. According to the World Health Organization (WHO), Sb species concentration lower than 20 ppb are acceptable for drinking water. According to a recent study, in 14 brands of bottled water from Canada, Sb concentrations increased on average 19% during 6 months storage at room temperature, but 48 brands of water from 11 European countries increased on average 90% under identical conditions. Therefore, a very important challenge for polyester catalysis is to come-up with a new Sb-free catalysts with low environmental impact. Intensive efforts have been made to find other stable and more environmental friendly non-antimony catalysts, such as those based on titanium. Titanium-based catalysts have been known for many years and actually are used for polybutylene terephthalate (PBT) and polypropylene terephthalate (PPT) production, however, polycondensation (PC) of PET manufacture is not well studied in literature. To date, only few esterification processes have been applied for the synthesis of PET by titanium catalysts. Herein, we report an efficient synthesis characterization and polymerization of PET for a series of new nontoxic organotitanium catalyst. Titanium metal has strong activity in polyesterification and forms stable complex with heteroatom-containing ligands (Scheme 1). These properties of titanium have been used advantageously in simple methods of syntheses and production of inexpensive metal catalyst. The high activity and selectivity of titanium-containing catalysts, their good solubility, and the absence of acidic effluent, which causes corrosion, are the reasons why these catalysts are frequently used in industry.

Yang, Youngkeun; Yoon, Seungwoong; Hwang, Yongtaek; Song, Bogeun [Honam Petrochemical Corporation, Daejeon (Korea, Republic of)

2012-10-15

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New Titanium-Based Catalysts for the Synthesis of Poly(ethylene terephthalate)  

International Nuclear Information System (INIS)

Poly(ethylene terephthalate) (PET) is a polymer with relatively low cost and high performance, which is widely used in various applications such as bottles, textile fibers, films and engineering plastics for automobiles and electric industries. Commercial catalysts used for synthesis of PET are in general antimony (Sb) compounds. Antimony(III) oxide, antimony(III) acetate and antimony(III) glycolate are used as a catalyst in 95% of PET manufacturing industries worldwide. The few organoantimony compounds that have been identified in environmental and biological samples are all in the form of methylated Sb-species. The Sb trace element is extremely toxic to mammals, and interferes with embryonic and fetal development, also, carcinogenic to humans. In addition to being found in drinking water, food packaging and soft-drink bottles. According to the World Health Organization (WHO), Sb species concentration lower than 20 ppb are acceptable for drinking water. According to a recent study, in 14 brands of bottled water from Canada, Sb concentrations increased on average 19% during 6 months storage at room temperature, but 48 brands of water from 11 European countries increased on average 90% under identical conditions. Therefore, a very important challenge for polyester catalysis is to come-up with a new Sb-free catalysts with low environmental impact. Intensive efforts have been made to find other stable and more environmental friendly non-antimony catalysts, such as those based on titanium. Titanium-based catalysts have been known for many years and actually are used for polybutylene terephthalate (PBT) and polypropylene terephthalate (PPT) production, however, polycondensation (PC) of PET manufacture is not well studied in literature. To date, only few esterification processes have been applied for the synthesis of PET by titanium catalysts. Herein, we report an efficient synthesis characterization and polymerization of PET for a series of new nontoxic organotitanium catalyst. Titanium metal has strong activity in polyesterification and forms stable complex with heteroatom-containing ligands (Scheme 1). These properties of titanium have been used advantageously in simple methods of syntheses and production of inexpensive metal catalyst. The high activity and selectivity of titanium-containing catalysts, their good solubility, and the absence of acidic effluent, which causes corrosion, are the reasons why these catalysts are frequently used in industry

14

A New Esterase from Thermobifida halotolerans Hydrolyses Polyethylene Terephthalate (PET and Polylactic Acid (PLA  

Directory of Open Access Journals (Sweden)

Full Text Available A new esterase from Thermobifida halotolerans (Thh_Est was cloned and expressed in E. coli and investigated for surface hydrolysis of polylactic acid (PLA and polyethylene terephthalate (PET. Thh_Est is a member of the serine hydrolases superfamily containing the -GxSxG- motif with 85–87% homology to an esterase from T. alba, to an acetylxylan esterase from T. fusca and to various Thermobifida cutinases. Thh_Est hydrolyzed the PET model substrate bis(benzoyloxyethylterephthalate and PET releasing terephthalic acid and mono-(2-hydroxyethyl terephthalate in comparable amounts (19.8 and 21.5 mmol/mol of enzyme while no higher oligomers like bis-(2-hydroxyethyl terephthalate were detected. Similarly, PLA was hydrolyzed as indicated by the release of lactic acid. Enzymatic surface hydrolysis of PET and PLA led to a strong hydrophilicity increase, as quantified with a WCA decrease from 90.8° and 75.5° to 50.4° and to a complete spread of the water drop on the surface, respectively.

Georg Steinkellner

2012-02-01

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Polyesters production from the mixture of phthalic acid, terephthalic and glycerol  

International Nuclear Information System (INIS)

Glycerin, a byproduct of biodiesel is currently an environmental and economic problem for producers of this renewable fuel in Brazil and in others parts of the world. In order to offer new proposals for recovery, it is used for the manufacture of polyesters used in applications in diverse areas such as construction and automobile industry. This work reports the production of polymer from the mixture of terephthalic and phthalic acid in three different proportions. The polyesters showed good thermal stability, analyzed by TGA and DSC, with an increase proportional to the terephthalic acid content. The X-ray diffraction patterns show that the samples are semi crystalline polymers. The micrographs indicated the presence of a smoother surface in the polyester that has a larger amount of phthalic acid, as reported in the literature. Therefore, the materials showed good thermal properties and morphological characteristics, so it consists in a new alternative to use glycerin. (author)

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Corrosion resistance of structural materials in solutions of dichloranhydrides of isophthalic and terephthalic acids  

International Nuclear Information System (INIS)

The production of promising thermally stable polymer materials, i.e., aromatic polyamides of Terlom, Phenylone, and polyarylates is associated with the application of solutions and melts of dichloranhydrides of isophthalic and terephthalic acids. Investigations were carried out on the corrosion resistance, in the melts of the dichloranhydrides of the isophthalic and terephthalic acids, of corrosion-resiting austenitic (12Kh18N10T, 10Kh17N13M2T, 08Kh17N15M3T, 06KhN28MDT), austenitic-ferritic (08Kh22N6T, 08Kh18G2N2T, 08Kh21N6M2T), ferritic (08Kh17T, 15Kh25T) steels and alloys, titanium VT1-0, titanium VT5-1 alloy, and welded joints in these materials. The specimens of the corrosion-resisting steels were welded by the electric arc method using the standard filler materials, and titanium and the titanium alloys were welded by argon-arc welding. On the basis of the experimental results, 08Kh21N6M2T steel and 06KhN28MDT alloy are recommended for the construction of equipment working in the melts of the dichloranhydride of the isophthalic acid, whereas equipment working in the melts of the dichloranhydride of the terephthalic acid at 90 C should be constructed from 08Kh21N6M2T steel

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Analysis of impurities in crude and highly-purified terephthalic acid by capillary electrophoresis  

OpenAIRE

In this work, a simple and fast capillary electrophoresis method for the simultaneous analysis of 4-carboxybenzaldehyde (4-CBA), p-toluic acid (pTOL) and benzoic acid (BZ) in industrial batches of crude (CTA) and highly-purified (PTA) terephthalic acid was developed. The electrophoretic conditions comprise: 20 mmol L-1 tetraborate buffer at pH 9, hydrodynamic injection (5 s/17 kPa), applied voltage of +30 kV and direct UV detection at 200 nm. The concentrations of 4-CBA and pTOL in five batch...

Moraes Maria de Lourdes L.; Rubim Joel C.; Realpozo Rene R.; Tavares Marina F. M.

2004-01-01

18

Direct electrospray ionization mass spectrometry quantitative analysis of sebacic and terephthalic acids in biodegradable polymers.  

Science.gov (United States)

A direct, rapid, and easy electrospray ionization mass spectrometry (ESI-MS) method to determine concentrations of sebacic acid (SA) and terephthalic acid (TA) residues in biodegradable copolymers was developed. Copolyester samples were synthesized from 1,4-butanediol and sebacic and terephthalic acids by melt polymerization. Extraction of monomers was performed in methanol. Their concentrations were determined by direct infusion ESI-MS, without chromatographic separation, using 1,12-dodecanedioic acid (DDA) as an internal standard. Calibration curves were obtained by plotting the ratio of the areas of the peaks relative to monomers and DDA standard as a function of their concentration ratio. We validated the method by determining the concentration of TA residue using both the ESI-MS protocol and high-performance liquid chromatography (HPLC) analysis with UV detection. The linearity range and the detection limit of this assay were 0.1-5.0 and 0.01 ppm for SA and 0.1-6.0 and 0.03 ppm for TA. This assay represents a useful alternative to conventional methods currently employed for acid quantification, resulting advantageous for its speed and high sensitivity. PMID:21204561

Rizzarelli, Paola; Zampino, Daniela; Ferreri, Loredana; Impallomeni, Giuseppe

2011-02-01

19

Surface-mediated nucleation in the solid-state polymorph transformation of terephthalic acid.  

Science.gov (United States)

A molecular mechanism for nucleation for the solid-state polymorph transformation of terephthalic acid is presented. New methods recently developed in our group, aimless shooting and likelihood maximization, are employed to construct a model for the reaction coordinate for the two system sizes studied. The reaction coordinate approximation is validated using the committor probability analysis. The transformation proceeds via a localized, elongated nucleus along the crystal edge formed by fluctuations in the supramolecular synthons, suggesting a nucleation and growth mechanism in the macroscopic system. PMID:17385859

Beckham, Gregg T; Peters, Baron; Starbuck, Cindy; Variankaval, Narayan; Trout, Bernhardt L

2007-04-18

20

Novel Tripartite Aromatic Acid Transporter Essential for Terephthalate Uptake in Comamonas sp. Strain E6  

OpenAIRE

It has been suggested that a novel type of aromatic acid transporter, which is similar to the tripartite tricarboxylate transporter (TTT), is involved in terephthalate (TPA) uptake by Comamonas sp. strain E6. This suggestion was based on the presence of the putative TPA-binding protein gene, tphC, in the TPA catabolic operon. The tphC gene is essential for growth on TPA and is similar to the genes encoding TTT-like substrate-binding proteins. Here we identified two sets of E6 genes, tctBA and...

Hosaka, Masaru; Kamimura, Naofumi; Toribami, Shotaro; Mori, Kosuke; Kasai, Daisuke; Fukuda, Masao; Masai, Eiji

2013-01-01

21

Biodegradable poly(terephthalate-co-phosphate)s: synthesis, characterization and drug-release properties  

OpenAIRE

To develop biodegradable polymers with favorable physicochemical and biological properties, we have synthesized a series of poly(terephthalate-co-phosphate)s using a two-step polycondensation. The diol 1,4-bis(2-hydroxyethyl) terephthalate was first reacted with ethylphosphorodichloridate (EOP), and then chain-extended with terephthaloyl chloride (TC). Incorporation of phosphate into the poly(ethylene terephthalate) backbone rendered the co-polymers soluble in chloroform and biodegradable, lo...

Mao, Hai-quan; Shipanova-kadiyala, Irina; Zhao, Zhong; Dang, Wenbin; Brown, Angela; Leong, Kam W.

2005-01-01

22

Biosynthesis of terephthalic acid, isophthalic acid and their derivatives from the corresponding dinitriles by tetrachloroterephthalonitrile-induced Rhodococcus sp.  

Science.gov (United States)

The nitrilase from Rhodococcus sp. CCZU10-1 catalyses the hydrolysis of dinitriles to acids without the formation of amides and cyanocarboxylic acids. It was induced by benzonitrile and its analogues (tetrachloroterephthalonitrile > ?-caprolactam > benzonitrile > phenylacetonitrile), and had activity towards aromatic nitriles (terephthalonitrile > tetrachloroterephthalonitrile > isophthalonitrile > tetrachloroisophthalonitrile > tetrafluoroterephthalonitrile > benzonitrile). After the optimization, the highest nitrilase induction [311 U/(g DCW)] was achieved with tetrachloroterephthalonitrile (1 mM) in the medium after 24 h at 30 °C after optimum enzyme activity was at pH 6.8 and at 30 °C. Efficient biocatalyst recycling was achieved by cell immobilization in calcium alginate, with a product-to-biocatalyst ratios of 776 g terephthalic acid/g DCW and 630 g isophthalic acid/g DCW. PMID:24101250

He, Yu-Cai; Wu, Ya-Dong; Pan, Xue-He; Ma, Cui-Luan

2014-02-01

23

Chemical recycling of poly(ethylene terephthalate). Application to the synthesis of multiblock copolyesters  

OpenAIRE

The chemical recycling of the poly(ethylene terephthalate), (PET), has been successfully carried out by glycolysis in the presence of bis (2-hydroxyethyl) terephthalate (BHET) resulting in the formation of hydroxytelechelic oligomers. These oligomers were then treated with carboxytelechelic poly(?-caprolactone) oligomers of Mn = 2300 and Mn = 730 g•mol–1 molecular weight, in the absence or presence of the titanium tetrabutyloxide (Ti(OBu)4) as a catalyst to get multiblock copolyesters. T...

Malek, F.; El Mejjatti, A.; Harit, T.; Riahi, A.; Khiari, R.; Bouabdallah, I.

2014-01-01

24

Photocatalytic ozonation of terephthalic acid: a by-product-oriented decomposition study.  

Science.gov (United States)

Terephthalic acid (TA) is considered as a refractory model compound. For this reason, the TA degradation usually requires a prolonged reaction time to achieve mineralization. In this study, vanadium oxide (VxOy) supported on titanium oxide (TiO2) served as a photocatalyst in the ozonation of the TA with light-emitting diodes (LEDs), having a bandwidth centered at 452 nm. The modified catalyst (VxOy/TiO2) in combination with ozone and LEDs improved the TA degradation and its by-products. The results obtained by this system were compared with photolysis, single ozonation, catalytic ozonation, and photocatalytic ozonation of VxOy/TiO2 with UV lamp. The LED-based photocatalytic ozonation showed almost the same decomposition efficiency of the TA, but it was better in comparison with the use of UV lamp. The oxalic acid accumulation, as the final product of the TA decomposition, was directly influenced by either the presence of VxOy or/and the LED irradiation. Several by-products formed during the TA degradation, such as muconic, fumaric, and oxalic acids, were identified. Besides, two unidentified by-products were completely removed during the observed time (60 min). It was proposed that the TA elimination in the presence of VxOy/TiO2 as catalyst was carried out by the combination of different mechanisms: molecular ozone reaction, indirect mechanism conducted by ·OH, and the surface complex formation. PMID:24946707

Fuentes, Iliana; Rodríguez, Julia L; Poznyak, Tatyana; Chairez, Isaac

2014-11-01

25

Chemical recycling of poly(ethylene terephthalate. Application to the synthesis of multiblock copolyesters  

Directory of Open Access Journals (Sweden)

Full Text Available The chemical recycling of the poly(ethylene terephthalate, (PET, has been successfully carried out by glycolysis in the presence of bis (2-hydroxyethyl terephthalate (BHET resulting in the formation of hydroxytelechelic oligomers. These oligomers were then treated with carboxytelechelic poly(?-caprolactone oligomers of Mn = 2300 and Mn = 730 g•mol–1 molecular weight, in the absence or presence of the titanium tetrabutyloxide (Ti(OBu4 as a catalyst to get multiblock copolyesters. The chemical structure of the synthesized copolyesters was investigated by size exclusion chromatography (SEC and proton Nuclear Magnetic Resonance (1H NMR spectroscopy. Moreover the differential scanning calorimetry (DSC was used to explore their thermal properties. The ester-ester interchange reaction was observed between the two oligopolyesters, was studied and discussed in detail.

F. Malek

2014-08-01

26

Atmospheric pressure synthesis of photoluminescent hybrid materials by sequential organometallic vapor infiltration into polyethylene terephthalate fibers  

Science.gov (United States)

Exposing a polymer to sequential organometallic vapor infiltration (SVI) under low pressure conditions can significantly modify the polymer's chemical, mechanical, and optical properties. We demonstrate that SVI of trimethylaluminum into polyethylene terephthalate (PET) can also proceed readily at atmospheric pressure, and at 60 °C the extent of reaction determined by mass uptake is independent of pressure between 2.5 Torr and 760 Torr. At 120 °C, however, the mass gain is 50% larger at 2.5 Torr relative to that at 760 Torr, indicating that the precursor diffusion in the chamber and fiber matrix decreases at higher source pressure. Mass gain decreases, in general, as the SVI process temperature increases both at 2.5 Torr and 760 Torr attributed to the faster reaction kinetics forming a barrier layer, which prevents further diffusion of the reactive species. The resulting PET/Al-Ox product shows high photoluminescence compared to untreated fibers. A physical mask on the polymer during infiltration at 760 Torr is replicated in the underlying polymer, producing an image in the polymer that is visible under UV illumination. Because of the reduced precursor diffusivity during exposure at 760 Torr, the image shows improved resolution compared to SVI performed under typical 2.5 Torr conditions.

Akyildiz, Halil I.; Mousa, Moataz Bellah M.; Jur, Jesse S.

2015-01-01

27

Acetate-assisted Synthesis of Chromium(III) Terephthalate and Its Gas Adsorption Properties  

International Nuclear Information System (INIS)

We report a facile synthetic approach of high-quality chromium(III) terephthalate [MIL-101(Cr)] by acetate-assisted method in the absence of toxic HF. Results indicate that the morphology and surface area of the MIL-101(Cr) can be tuned by modifying the molar ratio of acetate/Cr(NO3)3. The Brunauer-Emmett-Teller (BET) surface area of MIL-101(Cr) synthesized at the optimized condition can exceed 3300 m2/g. It is confirmed that acetate could promote the dissolution of di-carboxylic linker and accelerate the nucleation ratio. So the pure and small size of MIL-101(Cr) with clean pores can be obtained. CO2, CH4 and N2 adsorption isotherms of the samples are studied at 298 K and 313 K. Compared with the traditional method, MIL-101(Cr) synthesized by acetate-assisted method possess enhanced CO2 selective adsorption capacity. At 1.0 bar 298 K, it exhibits 47% enhanced CO2 adsorption capacity. This may be attributed to the high surface area together with clean pores of MIL-101(Cr)

28

Polyesters production from the mixture of phthalic acid, terephthalic and glycerol; Producao de poliesteres a partir da mistura de acido ftalico, tereftalico e glicerol  

Energy Technology Data Exchange (ETDEWEB)

Glycerin, a byproduct of biodiesel is currently an environmental and economic problem for producers of this renewable fuel in Brazil and in others parts of the world. In order to offer new proposals for recovery, it is used for the manufacture of polyesters used in applications in diverse areas such as construction and automobile industry. This work reports the production of polymer from the mixture of terephthalic and phthalic acid in three different proportions. The polyesters showed good thermal stability, analyzed by TGA and DSC, with an increase proportional to the terephthalic acid content. The X-ray diffraction patterns show that the samples are semi crystalline polymers. The micrographs indicated the presence of a smoother surface in the polyester that has a larger amount of phthalic acid, as reported in the literature. Therefore, the materials showed good thermal properties and morphological characteristics, so it consists in a new alternative to use glycerin. (author)

Carvalho, A.L.S.; Oliveira, J.C.; Miranda, C.S.; Boaventura, J.S.; Jose, N.M., E-mail: adrianaequfba@gmail.co [Universidade Federal da Bahia (GECIM/UFBA), Salvador, BA (Brazil). Inst. de Quimica. Grupo de Energia e Ciencias dos Materiais; Carvalho, R.F. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Escola Politecnica. Curso de Mestrado em Engenharia Ambiental Urbana

2010-07-01

29

A metal-organic framework assembled from Y(III), Li(I), and terephthalate: hydrothermal synthesis, crystal structure, thermal decomposition and topological studies.  

Science.gov (United States)

A novel metal-organic framework assembled from Y(iii), Li(i), and terephthalate ligand, formulated as [LiY(BDC)2(H2O)·2(H2O)] (1) (H2BDC = terephthalic acid), has been obtained as single phase under hydrothermal conditions. The crystal structure was solved by single-crystal X-ray diffraction and the bulk was characterized by powder X-ray diffraction (PXRD), thermal analyses (TG-MS and DSC), vibrational spectroscopy (FTIR), scanning/transmission electron microscopy (SEM-EDX, TEM, SAED, and BF-STEM-EDX), and powder X-ray thermodiffractometry (HT-XRD). 1 crystallizes in monoclinic space group (P21/c, with a = 11.6415(7) Å, b = 16.0920(4) Å, c = 13.2243(8) Å and ? = 132.23(1)°) and possesses a 3D framework with 1D trigonal channels running along the [101] direction containing water molecules. The structure of 1 is made up of unusual four-membered rings formed by edge- and vertex-shared {YO8} and {LiO4} polyhedra. The four-membered rings are isolated and connected to each other via carboxylate groups. HT-XRD reveals that 1 undergoes phase transformation upon the dehydration process which is a reversible process involving a spontaneous rehydration characterized by fast kinetics. Topological studies were also performed revealing that 1 has a new 2-nodal net. PMID:24562753

Abdelbaky, Mohammed S M; Amghouz, Zakariae; García-Granda, Santiago; García, José R

2014-04-21

30

Inhibitors of Fatty Acid Synthesis and Elongation  

Science.gov (United States)

Fatty acid synthesis and fatty acid elongation are two parts of a critically important pathway in plants. The endproducts are essential components of cell membranes, waxes, and suberin. Two chemical families of herbicide (groups that share similar chemical structures) inhibit fatty acid synthesis, while fatty acid elongation is inhibited by two other families. This lesson will provide an overview of fatty acid synthesis and elongation, and explain where herbicides inhibit the pathway. Mechanisms of resistance to these herbicides will be described.

31

Determination of zinc, cadmium, cobalt and nikel by flame atomic absorption spectrometry after preconcentration by poly(ethylene terephthalate) fibers grafted with methacrylic acid  

Science.gov (United States)

A method for the determination of Zn, Cd, Co and Ni by flame atomic absorption spectrophotometry after preconcentrating on poly(ethylene terephthalate) fibers grafted with methacrylic acid has been developed. The batch adsorption method was used for the preconcentration studies. Effect of pH, amount of adsorbent, concentration and volume of elution solution, shaking time and interfering ions on the recovery of the analytes have been investigated. Recoveries of Zn, Cd, Co and Ni were 97.3±0.4%, 98.3±0.2%, 94.1±0.3% and 96.5±0.6% at 95% confidence level, respectively, at optimum conditions. Langmuir adsorption isotherm curves were also studied for the analytes. The adsorption capacity of the adsorbent was found as 298, 412, 325 and 456 mg/g for Zn, Cd, Co and Ni, respectively. Poly(ethylene terephthalate) fibers grafted with methacrylic acid are suitable for repeated use without loss of capacity for more than thirty cycles. The proposed method was applied to the determination of trace metals in river water and synthetic sea water. Trace metals have been determined with high precision.

Ba?, Hüseyin; Türker, A. Rehber; Co?kun, Ramazan; Saçak, Mehmet; Yi?ito?lu, Mustafa

2000-07-01

32

Dibutylphosphoric acid synthesis  

International Nuclear Information System (INIS)

This work consists on the synthesis of dibutylphosphoric acis (DBP) by reaction of butanol with phosphorus pentoxid and on its separation by liquid-liquid extraction. It also deals with the characterization of DBP by some physicochemical analysis methods such as : chromatography, pH-metry and infrared and ultraviolet spectrophotometries. this study showed essentialy, that DBP can be formed in an appreciable amount (55%) when the reaction is realised with butanol/pentoxid molar ratio upper than 3 at temperature of 95 C

33

Morphology and thermal properties of electrospun fatty acids/polyethylene terephthalate composite fibers as novel form-stable phase change materials  

Energy Technology Data Exchange (ETDEWEB)

The ultrafine fibers based on the composites of polyethylene terephthalate (PET) and a series of fatty acids, lauric acid (LA), myristic acid (MA), palmitic acid (PA), and stearic acid (SA), were prepared successfully via electrospinning as form-stable phase change materials (PCMs). The morphology and thermal properties of the composite fibers were studied by field emission scanning electron microscopy (FE-SEM) and differential scanning calorimetry (DSC), respectively. It was found that the average fiber diameter increased generally with the content of fatty acid (LA) in the LA/PET composite fibers. The fibers with the low mass ratio maintained cylindrical shape with smooth surface while the quality became worse when the mass ratio is too high (more than 100/100). Moreover, the latent heat of the composite fibers increased with the increase of LA content and the phase transition temperature of the fibers have no obvious variations compared with LA. In contrast, both the latent heat and phase transition temperature of the fatty acid/PET composite fibers varied with the type of the fatty acids, and could be well maintained after 100 heating-cooling thermal cycles, which demonstrated that the composite fibers had good thermal stability and reliability. (author)

Chen, Changzhong [Key Laboratory of Cellulose and Lignocellulosics Chemistry, Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Linge [Key Laboratory of Cellulose and Lignocellulosics Chemistry, Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650 (China); Department of Chemistry, University of Sheffield, Sheffield S3 7HF (United Kingdom); Huang, Yong [Key Laboratory of Cellulose and Lignocellulosics Chemistry, Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Guangzhou 510650 (China); State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China)

2008-11-15

34

Synthesis of aminoaldonic acids  

DEFF Research Database (Denmark)

With the aim of synthesising aminoaldonic acids, two 2-acetamido-2-deoxyaldonolactones with D-galacto (6) and D-arabino (11) configuration were prepared from acetylated sugar formazans in analogy with a known procedure. Empolying the same procedure to acetylated sugar phenylhydrazones gave mixtures of 2,5-anhydrides and not the expected 2-acetamido-2-deoxy aldose phenylhydrazones. The acetylated phenylhydrazones were found to eliminate acetic acid when heated in aqueous ethanol and 1-phenylazoalkenes could be isolated by crystallisation. By this method the 17, 20, 23 and 25 were prepared from the phenylhydrazones of D-galactose, D-mannose, L-rhamnose and D-arabinose, respectively. The phenylazoalkenes were selectively reduced with sodium borohydride to give 2-deoxy aldose phenylhydrazones, which were hydrolysed to the corresponding 2-deoxy aldoses. Thus, 2-deoxy-D-lyxo-hexose (33), 2-deoxy-D-arabino-hexose (35), 2,6-dideoxy-L-arabino-hexose (37) and 2-deoxy-D-erythro-hexose (39) were prepared by this new method.Three new 2,3-aziridino-2,3-dideoxyhexonamides 43, 51 and 64 were prepared by a three step procedure from the readily available D-glucono-1,5-lactone, D-gulono-1,4-lactone and L-rhamnono-1,4-lactone, respectively. A 2,3-aziridino-2,3-dideoxypentonamide 70 was also prepared from D-glucono-1,5-lactone. The lactones were converted into methyl 3,4-O-isopropylidene-2-O-sulfonyl esters 42, 50, 62 and 68, which upon treatment with concentrated aqueous ammonia yielded the aziridino compounds. The aziridino amides 43 and 51 were reductively cleaved with hydrazine to give 3-amino-2,3-dideoxyhexonhydrazides 83 and 85, which were easily converted into the corresponding lactone 84 and acid 86. The aziridine ring of 43 and 51 was also opened with acetic acid to give the 3-amino-3-deoxyhexonic acids 79 and 82, respectively. The aminolactone 84 was converted into the corresponding amino sugar 89.With the aim of synthesising substrates for the Pictet-Spengler reaction three 4-aldehydo acetamidodideoxytetronolactones 92, 97and 103 were prepared by periodate cleavage of the corresponding hexonolactones. These compounds did not react with 2-(3,4-dimethoxyphenyl)ethyl amine 105. Instead the commercially available unsubstituted 4-carboxyl tetronolactone 108 was converted into the 2-(3,4-dimethoxyphenyl)ethyl amides 110 and 111 in two steps. These amides were cyclised by the Bischler-Napieralski cyclisation to give the dihydroisoquinoline lactones 113 and 114, which were reduced to give the target tetrahydroisoquinoline lactones 115, 117 and 118.

JØrgensen, Christel Thea

1997-01-01

35

Mechanical properties and morphology of biodegradable poly(lactic acid)/poly(butylene adipate-co-terephthalate) blends compatibilized by transesterification  

International Nuclear Information System (INIS)

Highlights: ? Compatibility between PLA and PBAT is improved through transesterification. ? Elongation at break of PLA was up to almost 300%. ? Both toughness and stiffness of PLA/PBAT blends are improved significantly after the incorporation of TBT. -- Abstract: Biodegradable poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) blends with various tetrabutyl titanate (TBT) concentration were prepared through melt-extrusion. Mechanical properties and morphology were characterized in terms of tensile and impact testing, dynamical mechanical analysis and scanning electron micrograph (SEM). The results indicated that the overall mechanical properties (including tensile strength, elongation at break, toughness and stiffness) of PLA/PBAT blends can be improved significantly after the incorporation of TBT. The SEM micrographs demonstrated that the compatibility and strong interaction between PLA and PBAT was improved via transesterification during melt-extrusion. The interfacial debonding, pullout of PBAT, yielding deformation were the most important mechanisms to improve toughness.

36

Modification of Poly(Ethylene Terephthalate) Fiber by Grafting of Acrylic Acid/Acrylamide for Removal of Pb+2 from Aqueous Solutions  

International Nuclear Information System (INIS)

A new fibrous adsorbent was prepared by grafting Acrylic Acid /Acryl Amide co-monomers onto Poly(Ethylene Terephthalate) fibers. The resulting sorbent has been characterized by Fourier Transform Infrared spectroscopy, Thermo Gravimetric Analysis, Scanning Electron Microscopy and elemental analysis and studied for the preconcentration and determination of trace Pb+2 ion from water sample. The effects of reaction conditions such as monomer mixture ratio, grafting yield, polymerization. The time and temperature on grafting were investigated. Batch adsorption method was used for the pre concentration studies. Recovery of Pb+2 was 100.2% at optimum conditions. The adsorption capacity of the adsorbent was found 44.1 mg/g for Pb+2.

37

Chemical recycling of post-consumer PET: structural characterization of terephthalic acid and the effect of Alkaline Hydrolysis at low temperature  

International Nuclear Information System (INIS)

Due to the environmental impact caused by PET packaging disposal, this material recycling has been thoroughly discussed and evaluated. In particular, chemical recycling enables achievement of the monomers that are used in PET resin manufacture: ethylene glycol (EG) and terephthalic acid (PTA). Therefore, studies for this process optimization are important from environmental and economic points of view. The present study investigated certain parameters that influence the depolymerization reaction of PET post-consumer via alkaline hydrolysis in order to obtain PTA. Assays were performed at 70 °C by varying the concentration of sodium hydroxide and the reaction time. The best results were obtained at 10.82 mol L-1 NaOH and 9 h reaction time. Consequently, it was possible to prove this process viability, once analyses by infrared and nuclear magnetic resonance confirmed that PTA was obtained in all reactions performed. (author)

38

Tetramethylammonium hydrogen terephthalate  

Directory of Open Access Journals (Sweden)

Full Text Available The asymmetric unit of the title salt, C4H12N+·C8H5O4?, contains one half of a tetramethylammonium cation and one half of a hydrogen terephthalate monoanion. The N atom of the ammonium cation lies on a twofold rotation axis and the centre of mass of the terephthalate anion is on a centre of inversion. In the crystal, the centrosymmetric terephthalate ions are linked by a very short symmetric O—H...O hydrogen bond [O...O = 2.4610?(19?Å] into a one-dimensional polymeric chain along [1-12]. The tetramethylammonium cations and terephthalate anions are then connected through a pair of bifurcated acceptor C—H...O hydrogen bonds, generating a three-dimensional supramolecular network. The carboxylate groups at both ends of the terephthalate anion are charge-shared with an equal probability of 0.5.

Leila Dolatyari

2012-10-01

39

Aldehyde-alcohol reactions catalyzed under mild conditions by chromium(III) terephthalate metal organic framework (MIL-101) and phosphotungstic acid composites.  

Science.gov (United States)

Porous materials based on chromium(III) terephthalate metal organic frameworks (MIL-101) and their composites with phosphotungstic acid (PTA) were studied as heterogeneous acid catalysts in aldehyde-alcohol reactions exemplified by acetaldehyde-phenol (A-P) condensation and dimethylacetal formation from benzaldehyde and methanol (B-M reaction). The MIL-101 was synthesized solvothermically in water, and the MIL101/PTA composite materials were obtained by either impregnation of the already prepared MIL-101 porous matrix with phosphotungstic acid solution or by solvothermic treatment of aqueous mixtures of Cr(NO(3))(3), and terephthalic and phosphotungstic acids. The MIL101/PTA materials appeared to be effective catalysts for both A-P and B-M reactions occurring at room temperature, with half-lives ranging from 0.5 h (A-P) to 1.5-2 h (B-M) and turnover numbers over 600 for A-P and over 2900 for the B-M reaction, respectively. A synergistic effect of the strong acidic moieties (PTA) addition to mildly acidic Brønsted and Lewis acid cites of the MIL-101 was observed with the MIL101/PTA composites. The ability of the PTA and MIL101/PTA materials to strongly absorb and condense acetaldehyde vapors was discovered, with the MIL101/PTA absorbing over 10-fold its dry weight of acetaldehyde condensate at room temperature. The acetaldehyde was converted rapidly to crotonaldehyde and higher-molecular-weight compounds while in contact with MIL-101 and MIL101/PTA materials. The stability of the MIL-101 and MIL101/PTA catalysts was assessed within four cycles of the 1-day alcohol-aldehyde reactions in terms of the overall catalyst recovery, PTA or Cr content, and reaction rate constants in each cycle. The loss of the catalyst over 4 cycles was approximately 10 wt % for all tested catalysts due to the incomplete recovery and minute dissolution of the components. The reaction rates in all cycles remained unchanged and the catalyst losses stopped after the third cycle. The developed MIL101/PTA composites appear to be feasible for industrial catalytic applications. PMID:22091761

Bromberg, Lev; Hatton, T Alan

2011-12-01

40

Exposure to the polyester PET precursor--terephthalic acid induces and perpetuates DNA damage-harboring non-malignant human breast cells.  

Science.gov (United States)

Identification of early perturbations induced in cells from non-cancerous breast tissue is critical for understanding possible breast cancer risk from chemical exposure. We have demonstrated previously that exposure to the ubiquitous xenoestrogens, bisphenol A (BPA) and methyl paraben, promotes the hallmarks of cancer in non-malignant human high-risk donor breast epithelial cells (HRBECs) isolated from several donors. Here we show that terephthalic acid (TPA), a major chemical precursor of polyethylene terephthalate (PET) containers used for the storage of food and beverages, increased the ER?: ER? ratio in multiple HRBEC samples, suggesting an estrogenic effect. Although, like BPA and methyl paraben, TPA also promoted resistance to tamoxifen-induced apoptosis, unlike these chemicals instead of inducing an increased S-phase fraction, TPA treatment arrested cell proliferation. DNA-PK, ATM and members of the MRN complex, known to be involved in DNA damage sensor and effector proteins, were elevated indicating induction of DNA strand breaks. Early DNA damage checkpoint response, mediated through p53/p21, led to G1 arrest in TPA-exposed cells. Removal of TPA from the growth medium resulted in the rapid induction of BCL2, increasing the ratio of anti-: pro-apoptotic proteins, together with overexpression of Cyclin A/CDK2 proteins. Consequently, despite elevated p53(pSer15) and H2AX(pSer139), indicating sustained DNA damage, TPA exposed cells resumed robust growth rates seen prior to TPA exposure. The propensity for the perpetuation of DNA aberrations that activate DNA damage pathways in non-malignant breast cells justifies careful consideration of human exposure to TPA, particularly at vulnerable life stages. PMID:25411358

Luciani-Torres, Maria Gloria; Moore, Dan H; Goodson, William H; Dairkee, Shanaz H

2015-01-01

41

Fatty acid synthesis by spinach chloroplasts, 3  

International Nuclear Information System (INIS)

The modes of actions of photosynthetic inhibitors on photosynthesis and fatty acid synthesis were examined. DCMU, an electron transport inhibitor, inhibited fatty acid synthesis and photophosphorylation to the same extent, suggesting dependence of fatty acid synthesis on photosynthesis. The same was also the case with FCCP, a photophosphorylation uncoupler. In contrast, NH4Cl and phlorizin at concentrations completely suppressing ATP formation, only partially inhibited the fatty acid synthesis. These facts suggest that a certain level of high-energy intermediate (state) is responsible for the light enhancement of fatty acid synthesis. This idea is further supported by the fact that the partial inhibition of fatty acid synthesis by NH4Cl was relieved by addition of DCCD at low concentrations suppressing the ATP formation but not completely destroying the high energy intermediate. The lag period in the initial period of fatty acid synthesis was shortened by preillumination of chloroplasts, even in the absence of ADP. This indicates that the light dependent fatty acid synthesis is closely associated with the high-energy intermediate (state), but not directly with ATP formation by photophosphorylation. (author)

42

A new approach of synthesis and morphological control of poly(ethylene terephthalate)-g-polyacrylonitrile composite film with a porous surface  

Science.gov (United States)

Poly(ethylene terephthalate)-g-polyacrylonitrile (PET-g-PAN) composite film with a porous surface was fabricated via gamma-ray-radiation-induced graft polymerization on PET film in an aqueous solution system. The original PET film was first irradiated by gamma ray in the aqueous solution of acrylic acid. Next, the graft polymerization of acrylonitrile (AN) was induced by gamma ray on the surface of the above modified PET film in an aqueous solution of AN. The prepared PET-g-PAN composite film has a smaller static water contact angle than the original PET film. The SEM and AFM images show that the grafted PAN layer on the surface of PET-g-PAN composite film is composed of closely-arranged spherical PAN microspheres with an average diameter of 30 nm. The gaps between the PAN microspheres form fine pores (less than 30 nm) on the surface. The gas barrier property of the PET-g-PAN composite film is much better than that of the original PET film. This work provides a facile and green method to prepare PET-g-PAN composite film with a controllable porous surface morphology by taking advantage of the radiation-induced graft polymerization technique in an aqueous solution system.

Xu, Yongfei; Wang, Yunlong; Wang, Mozhen; Wu, Qichao; Zhou, Xiao; Ge, Xuewu

2015-01-01

43

Synthesis and diagnostic use of ?-substituted fatty acids  

International Nuclear Information System (INIS)

The application, evaluation and synthesis are discussed of the radioiodinated ?-substituted fatty acids used as myocardial imaging agents. The possibilities of the synthesis of all modifications of the radiolabelled fatty acids - ?-halogen acids, ?(p-iodophenyl) acids, ?-5-iodothienyl acids, ?-substituted ?- and ?-methyl-branched fatty acids, ?-iodoalkenyl fatty acids and ?-substituted tellurium fatty acids are demonstrated. The iodination methods are also included. (author)

44

Preparation, morphology and thermal properties of electrospun fatty acid eutectics/polyethylene terephthalate form-stable phase change ultrafine composite fibers for thermal energy storage  

International Nuclear Information System (INIS)

Highlights: ? Electrospun binary fatty acid eutectics/PET ultrafine composite fibers were prepared. ? Fatty acid eutectics had appropriate phase transition temperature and heat enthalpy. ? Their morphological structures and thermal properties were different from each other. ? Composite fibers could be innovative form-stable PCMs for thermal energy storage. - Abstract: The ultrafine composite fibers based on the composites of binary fatty acid eutectics and polyethylene terephthalate (PET) with varied fatty acid eutectics/PET mass ratios (50/100, 70/100, 100/100 and 120/100) were fabricated using the technique of electrospinning as form-stable phase change materials (PCMs). The five binary fatty acid eutectics including LA–MA, LA–PA, MA–PA, MA–SA and PA–SA were prepared according to Schrader equation, and then were selected as an innovative type of solid–liquid PCMs. The results characterized by differential scanning calorimeter (DSC) indicated that the prepared binary fatty acid eutectics with low phase transition temperatures and high heat enthalpies for climatic requirements were more suitable for applications in building energy storage. The structural morphologies, thermal energy storage and thermal stability properties of the ultrafine composite fibers were investigated by scanning electron microscope (SEM), DSC and thermogravimetric analysis (TGA), respectively. SEM images revealed that the electrospun binary fatty acid eutectics/PET ultrafineutectics/PET ultrafine composite fibers possessed the wrinkled surfaces morphologies compared with the neat PET fibers with cylindrical shape and smooth surfaces; the grooves or ridges on the corrugated surface of the ultrafine composite fibers became more and more prominent with increasing fatty acid eutectics amount in the composite fibers. The fibers with the low mass ratio maintained good structural morphologies while the quality became worse when the mass ratio is too high (more than 100/100). DSC measurements suggested that the heat enthalpies of melting and crystallization of the ultrafine composite fibers increased gradually with increasing fatty acid eutectics amounts, but their phase transition temperatures had almost no obvious variation as relative to the corresponding fatty acid eutectics. Meanwhile, the characteristic temperatures and heat enthalpies of the ultrafine composite fibers varied with the different types of binary fatty acid eutectics. TGA results indicated that the degradation of electrospun binary fatty acid eutectics/PET ultrafine composite fibers with representative mass ratio of 100/100 had two steps and corresponded respectively to the degradations of binary fatty acid eutectics and PET polymer chains; and the charred residue at 700 °C of the composite fibers was lower than that of the neat PET fibers. It could be envisioned that the electrospun binary fatty acid eutectics/PET composite fibers would be extensively used for latent heat storage in the field of building energy conservation.

45

Synthesis of derivatives of tetronic acid and pulvinic acid. Total synthesis of norbadione A  

International Nuclear Information System (INIS)

When vegetables like mushrooms are contaminated by radioactive caesium 137, this radioactive caesium is associated to norbadione A, a natural pigment present in two mushroom species and which can be used as a caesium decorporation agent or maybe as protection agent against ionizing radiations. Within this perspective, this research report describes the biosynthesis and the structure and properties of the norbadione A and of pulvinic acids (physicochemical properties, anti-oxidizing properties). Then, it presents the various tetronic acids (3-acyl-, 3-alkyl-, 3-alkoxy-, 3-aryl-tetronic acids and non 3-substituted tetronic acids), their synthesis path as they are described in the literature, and presents a new synthesis approach using a tandem reaction (with different esters or hydroxy esters) and the synthesis of tetronic acids. The author also proposes a new synthesis way for methyl pulvinates, and finally reports the work on the development of a total synthesis of the norbadione A

46

Concise total synthesis of (±)-actinophyllic acid.  

Science.gov (United States)

A concise total synthesis of the complex indole alkaloid (±)-actinophyllic acid was accomplished by a sequence of reactions requiring only 10 steps from readily-available, known starting materials. The approach featured a Lewis acid-catalyzed cascade of reactions involving stabilized carbocations that delivered the tetracyclic core of the natural product in a single chemical operation. Optimal conversion of this key intermediate into (±)-actinophyllic acid required judicious selection of a protecting group strategy. PMID:24882888

Granger, Brett A; Jewett, Ivan T; Butler, Jeffrey D; Martin, Stephen F

2014-07-01

47

Enantioselective total synthesis of plectosphaeroic acid B.  

Science.gov (United States)

The first total synthesis of a member of the plectosphaeroic acid family of fungal natural products is reported. Key steps include the late-stage formation of the hindered N6-C9" bond and stereoselective introduction of the two methylthio substituents. PMID:23452064

Jabri, Salman Y; Overman, Larry E

2013-03-20

48

Synthesis of labelled nordihydroguaiaretic acid  

International Nuclear Information System (INIS)

Meso-2,3-Dimethyl-1,4-bis(3,4-dihydroxyphenyl)butane-1-14C, (meso-nordihydroguaiaretic acid-1-14C, NDGA-1-14C), was prepared. meso-2,3-Dimethyl-1,4-bis(dihydroxy-2,5,6-trideuterophenyl)butane (NDGA-d6, ring labelled) was made from acid exchange of unlabelled natural product and meso-2,3-dimethyl-1,4-bis(3,4-dihydroxyphenyl)-1,1,2,4,4-hexadeuterobutane (NDGA-d6, chain labelled) was prepared from hydrogenation of 3,4-dimethyl-2,5-bis-(3,4-dimethoxyphenyl)furan using deuterium and Pd/C catalyst. (author)

49

Microwave irradiated synthesis and characterization of 1, 4-phenylene bis-oxazoline form bis-(2-hydroxyethyl terephthalamide obtained by depolymerization of poly (ethylene terephthalate (PET bottle wastes  

Directory of Open Access Journals (Sweden)

Full Text Available The aminolytic depolymerization of PET bottle waste with ethanolamine by conventional heating and microwave irradiation heating method was attempted with heterogeneous, recyclable acid catalysts such as beta zeolite (SiO2/ AlO2= 15 Na- form and montmorillonite KSF. The pure product bis-(2-hydroxyethyl terephthalamide (BHETA of aminolysis was obtained in good yield (85- 88%. The BHETA, thus obtained, was subjected to cyclization reaction by heating with polyphosphoric acid as well as by chlorination (using phosphoryl chloride, bromination (using red phosphorous and liquid bromine and nitration (conc. HNO3 + conc. H2SO4 followed by conventional and microwave irradiation heating in N,N- dimethyl formamide/ potassium carbonate solution. The product so obtained was 2, 2’-(1,4-phenylene–bis-(2-oxazoline (PBO, which has applications in polymer synthesis as a chain extender/ chain coupling agent or a cross linker. The productswere analyzed by FTIR, DSC, Mass and NMR (1H and 13C NMR.

Yogesh S. Parab

2012-04-01

50

Synthesis of a conformationally constrained ?-amino acid building block.  

Science.gov (United States)

Conformationally restricted amino acids are important components in peptidomimetics and drug design. Herein, we describe the synthesis of a novel, non-proteinogenic constrained delta amino acid containing a cyclobutane ring, cis-3(aminomethyl)cyclobutane carboxylic acid (ACCA). The synthesis of the target amino acid was achieved in seven steps, with the key reaction being a base induced intramolecular nucleophilic substitution. A small library of dipeptides was prepared through the coupling of ACCA with proteinogenic amino acids. PMID:22851051

O'Reilly, Elaine; Pes, Lara; Ortin, Yannick; Müller-Bunz, Helge; Paradisi, Francesca

2013-02-01

51

Solid-State Condensation Polymerization of Aromatic Oligoesters from Bisphenol A Diphenyl Terephthalate/Isophthalate Mixtures; Bisufenoru A, jifueniruterefutarato/isofutarato kara naru hokozoku origoesuteru no kosoju shukugo  

Energy Technology Data Exchange (ETDEWEB)

Industrially avaliable aromatic polyesters of bisphenol A polyaryate is conventionally produced by the interfacial condensation polymerization of bishenol A and the mixture of terephthaloyl/isophtaloyl chlorides. We now report a new synthetic method without using the acid chloride derivatives. The synthesis of oligomeric polyarylate by the melt condensation polymerization of bisphenol A and diphenyl terephthalate/isophthalate(mole ratio of reactants is 1/0.5/0.5), and the crystallization of this oligomeric polyarylate contacting with the proper solvent have been previously repoted. This crystallized oligomeric pllyarylate could be polymerized by the solid-state condedsation polymerization into a high molwcular weight polymer with excellent color. The key point to obatin a high molwcular weight polymer was to abjust precisely the mole ratio of the edn-grops of -OH and phenyl. The molecular weight of the obtained polymer reached to twice that of the commercial polymer reached to twece that of the commercial polyarylate and the molecular weigt distribution had the most probable distribution of M{sub w}/M{sub n}=2. The high molecular weight polyarylate showed an excellent wear property. The melting points of the obtaned polymers were over 280 , and some polymers showed a melting point over 300degreeC. These values were nearly 40degreeC higher than the reported value of the maximum melting point of the random copolyarylate composed of bisphenol A, terephthalic and isophthalic acid(mole ratio of bisphenol A/terephthalic/isophthalic acid=1/0.5/0.5). (author)

Iwamoto, Takashi.; Kinoshita, Takashi. [Asahi Chemical Industry Corp., Okayama (Japan). Chemicals and Plastics Development Laboratory; Masamoto, Junzo. [Kyoto Institure of Technology, Kyoto (Japan). Department of Ploymer Science Engineering

1999-03-10

52

Hyaluronic acid lipoate: synthesis and physicochemical properties.  

Science.gov (United States)

The synthesis and physicochemical characterisation of mixed lipoic and formic esters of hyaluronan (Lipohyal) are presented in this paper. The synthesis was conducted by activating lipoic acid with 1,1'-carbonyldiimidazole to obtain lipoyl imidazolide, which reacted with hyaluronan (HA) in formamide under basic conditions. This procedure allows researchers to modulate easily the degree of substitution over a range of 0.05-1.8. Radical scavenger properties were analysed by UV-vis spectroscopy, where improved performance was demonstrated for Lipohyal with respect to the HA row material and lipoic acid. The chemical modification also causes HA to show an improved resistance to hyaluronidase digestion. These findings show that Lipohyal is a highly interesting derivative for applications in the tricological and dermo-cosmetic field and as an anti-aging ingredient. Moreover, Lipohyal can be easily crosslinked by UV irradiation, resulting in an innovative hydrogel with distinctive viscoelastic properties that is suitable as both a dermal-filler and as an intra-articular medical device. PMID:23465930

Picotti, Fabrizio; Fabbian, Matteo; Gianni, Rita; Sechi, Alessandra; Stucchi, Luca; Bosco, Marco

2013-03-01

53

Synthesis of novel acid electrolytes for phosphoric acid fuel cells  

Science.gov (United States)

A 40 millimole per hour scale aerosol direct fluorination reactor was constructed. F-Methyl F-4-methoxybutanoate and F-4-methoxybutanoyl fluoride were synthesized by aerosol direct fluorination of methyl 4-methoxybutanoate. Basic hydrolysis of the perfluorinated derivatives produce sodium F-4 methoxybutanoate which was pyrolyzed to F-3-methoxy-1-propene. Purification and shipment of 33 grams of F-3-methoxy-1-propene followed. Syntheses by analogous methods allowed production and shipment of 5 grams of F-3-ethoxy 1-propene, 18 grams of F-3-(2-methoxy.ethoxy) 1-propene, and 37 grams of F-3,3-dimethyl 1-butene. Eighteen grams of F-2,2-dimethyl 1-chloropropane was produced directly and shipped. As suggested by other contractors, 5 grams of F-3-methoxy 1-iodopropane, and 5 grams of F-3-(2-methoxy.ethoxy) 1-iodopropane were produced by converting the respective precursor acid sodium salts produced for olefin synthesis to the silver salts and pyrolyzing them with iodine. Each of these compounds was prepared for the first time by the aerosol fluorination process during the course of the contract. These samples were provided to other Gas Research Institute (GRI) contractors for synthesis of perfluorinated sulfur (VI) and phosphorous (V) acids.

Adcock, James L.

1988-11-01

54

Radiation chemistry of the terephthalate dosimeter  

International Nuclear Information System (INIS)

Cobalt-60 ?-irradiated aqueous sodium terephthalate solutions have been studied; in aerated 4 x 10-4 M sodium hydroxide solutions, the main products are hydroxyterephthalate (HTA) (G = 0.99 +- 0.01), carbonate (G = 1.31 +- 0.08), and peroxides (G = 2.84 +- 0.04). The HTA and carbonate species are formed by hydroxyl radical attack and account for approximately 90% of hydroxyl radical reactions. The ortho-, meta-, and para-hydroxybenzoic acids, if formed at all, cannot have G values greater than 0.03, 0.10, and 0.27, respectively; their formation in concentrations corresponding to the maximum yields will not contribute significantly to the fluorescence attributed to the HTA. Oxygen must be present for efficient conversion of the terephthalate-OH radical adduct to HTA, and oxygenation increases G(HTA) above the aerated solution value; but no evidence was found for HTA and CO2 formation from primary radiolytic species other than the hydroxyl radical. G(HTA) is unaffected by changes in terephthalate concentration between 1 x 10-4 and 1 x 10-2 M in sodium hydroxide solutions at pH 10, but it is affected in the solution pH is decreased. In phosphate-buffered solutions at pH 6.85, G(HTA) is 0.93 +- 0.01; a further decrease in solution pH yields lower values. The lowering of the G(HTA) value is attributed to recombination reactions between the terephthalate-OH radical products and reducing radical products. Support for the recombinadical products. Support for the recombination postulate was obtained from measurement of a parallel decrease in the peroxide yield and the observation of a dose-rate efect on G(HTA). Competition kinetic studies with added solutes carbonate and bicarbonate gave the rate ratios k(OH + TA2-):k(OH + CO32-):k(OH + HCO3-) = 1:0.106:0.0036

55

Scientific Opinion on the safety evaluation of the active substances, terephthalic acid, dimethyl ester , polymer with 1,4-butanediol, cyclized, polymers with glycidyl methacrylate, hydroxyl-terminated polybutadiene, methyl methacrylate and styrene, and cobalt stearate for use in food contact materials  

OpenAIRE

This scientific opinion of EFSA deals with the safety evaluation of the oxygen absorber (terephthalic acid, dimethyl ester, polymer with 1,4-butanediol, cyclized, polymers with glycidyl methacrylate, hydroxyl-terminated polybutadiene, methyl methacrylate and styrene) copolymer (CAS No 1223402-34-3, FCM substance No 1005) and the oxidation catalyst cobalt stearate (CAS No 1002-88-6 and FCM Substance No 1004), intended to be used up to a maximum percentage of 1% in polyethylene terepht...

Efsa Panel On Food Contact Materials, Enzymes

2012-01-01

56

Identification of di-2-ethylhexyl terephthalate (DEHTP) metabolites using human liver microsomes for biomonitoring applications.  

Science.gov (United States)

Di-2-ethylhexyl terephthalate (DEHTP), a structural isomer of the plasticizer di-2-ethylhexyl phthalate (DEHP), is used in food packaging and medical devices, among other applications, and is a potential replacement for DEHP and other ortho-phthalate plasticizers. Identifying sensitive and specific biomarkers of DEHTP is necessary to assess humans' background exposure to DEHTP. Using mass spectrometry, we investigated the metabolism of DEHTP by human liver microsomes to identify in vitro DEHTP metabolites. We unequivocally identified terephthalic acid (TPA) and mono-2-ethylhydroxyhexyl terephthalate (MEHHTP), using authentic standards, and tentatively identified mono-2-ethylhexyl terephthalate (MEHTP) and two other oxidative metabolites of DEHTP: mono-2-ethyloxohexyl terephthalate (MEOHTP), and mono-2-ethyl-5-carboxypentyl terephthalate (MECPTP) from their mass spectrometry fragmentation patterns. We also evaluated the formation of in vitro metabolites of DEHP. DEHTP and DEHP produced similar metabolites, but their metabolite profiles differed considerably. DEHTP metabolized to form TPA, a metabolite of several terephthalates, as the major in vitro metabolite, followed by MEHTP, MEHHTP, MEOHTP and MECPTP. MEHTP, MEHHTP, MEOHTP and MECPTP, which are specific metabolites of DEHTP, may be suitable biomarkers for assessing exposure to DEHTP. Nonetheless, data on the urinary excretion fraction and temporal stability of these metabolites, among other considerations, are needed to demonstrate their utility as exposure biomarkers. PMID:25687528

Silva, Manori J; Samandar, Ella; Calafat, Antonia M; Ye, Xiaoyun

2015-06-01

57

Poli(tereftalato de etileno, PET: uma revisão sobre os processos de síntese, mecanismos de degradação e sua reciclagem Poly(ethylene terephthalate, PET: a review on the synthesis processes, degradation mechanisms and its recycling  

Directory of Open Access Journals (Sweden)

Full Text Available Apresentamos uma revisão sobre o poli(tereftalato de etileno enfatizando os processos de síntese e os mecanismos de degradação. Atualmente o Brasil apresenta um dos maiores índices mundiais de reciclagem mecânica deste polímero, correspondendo a um percentual de 53%. O sucesso desse termoplástico na indústria de reciclagem deve-se à sua ampla diversidade de aplicações, desde a indústria têxtil (multifilamento até as indústrias de alimentos, onde as embalagens recicladas grau alimentício poderão ser misturadas com a resina virgem em diversas proporções e reprocessadas para o uso. Uma abordagem sobre a atual legislação do uso de PET reciclado em contato com alimentos também é mostrada neste trabalho. No processo de síntese do PET realizado em duas ou três etapas, são usados comonômeros e aditivos para otimizar as condições de processamento do material. Entretanto, tanto durante a síntese como no processo de reciclagem, ocorrem reações de degradação (termomecânica e termo-oxidativa e reações secundárias, formando acetaldeído, oligômeros, e o dietileno glicol. A presença desses "contaminantes" acelera o processo de degradação do polímero, afetando a qualidade do produto final.We present a review on poly(ethylene terephthalate, emphasizing the synthesis processes and the degradation mechanisms. Brazil is currently among the countries that most recycle PET, with 53% of this polymer being mechanically recycled. The success of this thermoplastic in the recycling industry is due to its large diversity of applications, from the textile industry to food packaging, where the food grade recycled packages will be mixed with the pristine resin for reprocessing and use. We also discuss the present legal aspects concerning PET recycling and its use in contact with food. In the synthesis of PET, usually done in two or three steps, several co-monomers and additives are used to optimize the final properties and processing conditions. Additionally, during the synthesis, processing and recycling, several degradation (thermomechanical and thermo-oxidation and secondary reactions occur, producing acetaldehydes, oligomers and diethyleneglicol. The presence of these "contaminants" accelerates the degradation process of the polymer affecting the final product characteristics.

Wanderson Romão

2009-06-01

58

Poli(tereftalato de etileno), PET: uma revisão sobre os processos de síntese, mecanismos de degradação e sua reciclagem / Poly(ethylene terephthalate), PET: a review on the synthesis processes, degradation mechanisms and its recycling  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Apresentamos uma revisão sobre o poli(tereftalato de etileno) enfatizando os processos de síntese e os mecanismos de degradação. Atualmente o Brasil apresenta um dos maiores índices mundiais de reciclagem mecânica deste polímero, correspondendo a um percentual de 53%. O sucesso desse termoplástico n [...] a indústria de reciclagem deve-se à sua ampla diversidade de aplicações, desde a indústria têxtil (multifilamento) até as indústrias de alimentos, onde as embalagens recicladas grau alimentício poderão ser misturadas com a resina virgem em diversas proporções e reprocessadas para o uso. Uma abordagem sobre a atual legislação do uso de PET reciclado em contato com alimentos também é mostrada neste trabalho. No processo de síntese do PET realizado em duas ou três etapas, são usados comonômeros e aditivos para otimizar as condições de processamento do material. Entretanto, tanto durante a síntese como no processo de reciclagem, ocorrem reações de degradação (termomecânica e termo-oxidativa) e reações secundárias, formando acetaldeído, oligômeros, e o dietileno glicol. A presença desses "contaminantes" acelera o processo de degradação do polímero, afetando a qualidade do produto final. Abstract in english We present a review on poly(ethylene terephthalate), emphasizing the synthesis processes and the degradation mechanisms. Brazil is currently among the countries that most recycle PET, with 53% of this polymer being mechanically recycled. The success of this thermoplastic in the recycling industry is [...] due to its large diversity of applications, from the textile industry to food packaging, where the food grade recycled packages will be mixed with the pristine resin for reprocessing and use. We also discuss the present legal aspects concerning PET recycling and its use in contact with food. In the synthesis of PET, usually done in two or three steps, several co-monomers and additives are used to optimize the final properties and processing conditions. Additionally, during the synthesis, processing and recycling, several degradation (thermomechanical and thermo-oxidation) and secondary reactions occur, producing acetaldehydes, oligomers and diethyleneglicol. The presence of these "contaminants" accelerates the degradation process of the polymer affecting the final product characteristics.

Wanderson, Romão; Márcia A. S., Spinacé; Marco-A. De, Paoli.

2009-06-01

59

Synthesis of dimethyl-tartaric acid from aqueous solutions of pyruvic acid induced by ?-rays  

International Nuclear Information System (INIS)

The synthesis of 2,3 dimethyl-tartaric acid (DMTA) can be achieved in one step using pyruvic acid as raw material and ionizing radiation as an energy source. The reaction may have synthetic applications because the reduction product was nearly exclusively DMTA (? 73%) which easily can be isolated and purified. Other products were carbon dioxide, acetic acid and some polycarboxylic acids. (author)

60

Facile synthesis of ?-hydroxy carboxylic acids from the corresponding ?-amino acids  

DEFF Research Database (Denmark)

An effective and improved procedure is developed for the synthesis of ?-hydroxy carboxylic acids by treatment of the corresponding protonated ?-amino acid with tert-butyl nitrite in 1,4-dioxane-water. The amino moiety must be protonated and located ? to a carboxylic acid function in order to undergo initial diazotization and successive hydroxylation, since neither ?-amino acids nor acid derivatives such as esters and amides undergo hydroxylations. The method is successfully applied for the synthesis of 18 proteinogenic amino acids. © 2014 Elsevier Ltd. All rights reserved.

Stuhr-Hansen, Nicolai; Padrah, Shahrokh

2014-01-01

61

Mitochondrial Fatty Acid Synthesis Type II: More than Just Fatty Acids*  

OpenAIRE

Eukaryotes harbor a highly conserved mitochondrial pathway for fatty acid synthesis (FAS), which is completely independent of the eukaryotic cytosolic FAS apparatus. The activities of the mitochondrial FAS system are catalyzed by soluble enzymes, and the pathway thus resembles its prokaryotic counterparts. Except for octanoic acid, which is the direct precursor for lipoic acid synthesis, other end products and functions of the mitochondrial FAS pathway are still largel...

Hiltunen, J. Kalervo; Schonauer, Melissa S.; Autio, Kaija J.; Mittelmeier, Telsa M.; Kastaniotis, Alexander J.; Dieckmann, Carol L.

2009-01-01

62

Lysophosphatidic acid synthesis and phospholipid metabolism in rat mast cells  

International Nuclear Information System (INIS)

The role of lysophosphatidic acid in mast cell response to antigen was investigated using an isolated rat serosal mast cell model. The cells were incubated with monoclonal murine immunoglobulin E to the dinitrophenyl hapten and prelabeled with 32P-orthophosphate or 3H-fatty acids. Lysophosphatidic acid was isolated form cell extracts by 2-dimensional thin-layer chromatography, and the incorporated radioactivity was assessed by liquid scintillation counting. Lysophosphatidic acid labeling with 32P was increased 2-4 fold within 5 minutes after the addition of antigen or three other mast cell agonists. Functional group analyses unequivocally showed that the labeled compound was lysophosphatidic acid. Lysophosphatidic acid synthesis was dependent on the activity of diacylglycerol lipase, suggesting formation from monoacylglycerol. In addition, the studies of lysophosphatidic acid synthesis suggest that the addition of antigen to mast cells may initiate more than one route of phospholipid degradation and resynthesis. Whatever the origin of lysophosphatidic acid, the results of this study demonstrated that lysophosphatidic acid synthesis is stimulated by a variety of mast cell agonists. Dose-response, kinetic, and pharmacologic studies showed close concordance between histamine release and lysophosphatidic acid labeling responses. These observations provide strong evidence that lysophosphatidic acid plays an important role in mast cell activplays an important role in mast cell activation

63

Convenient synthesis of N1-substituted orotic acid derivatives.  

Science.gov (United States)

A convenient and efficient method for the synthesis of N1-substituted orotic acid derivatives is reported. The synthetic route utilizes substituted maleimide as synthetic intermediate and takes only four simple steps from readily available starting materials. As a result, orotic acid derivatives with various alkyl and aromatic groups at N1 can be readily synthesized. PMID:25364061

Bowler, Jeannette T; Clausen, Caitlin R; Blackburn, Daniel J; Wu, Weiming

2014-11-19

64

Oleochemical synthesis of an acid cleavable hydrophobe for surfactant use  

Science.gov (United States)

The synthesis of a series of branched hydroxy stearates from commercially available methyl oleate and common organic acids is reported. A variety of different acids, with 3 to 8 carbon atoms, and also varying in their branching and functionality, were used. The kinetics of the ring opening reactio...

65

Synthesis modulation as a tool to increase the catalytic activity of metal-organic frameworks: the unique case of UiO-66(Zr).  

Science.gov (United States)

The catalytic activity of the zirconium terephthalate UiO-66(Zr) can be drastically increased by using a modulation approach. The combined use of trifluoroacetic acid and HCl during the synthesis results in a highly crystalline material, with partial substitution of terephthalates by trifluoroacetate. Thermal activation of the material leads not only to dehydroxylation of the hexanuclear Zr cluster but also to post-synthetic removal of the trifluoroacetate groups, resulting in a more open framework with a large number of open sites. Consequently, the material is a highly active catalyst for several Lewis acid catalyzed reactions. PMID:23875753

Vermoortele, Frederik; Bueken, Bart; Le Bars, Gaëlle; Van de Voorde, Ben; Vandichel, Matthias; Houthoofd, Kristof; Vimont, Alexandre; Daturi, Marco; Waroquier, Michel; Van Speybroeck, Veronique; Kirschhock, Christine; De Vos, Dirk E

2013-08-01

66

Possibilities of enzyme synthesis of radioactive nuclei acid components  

International Nuclear Information System (INIS)

The possibilities of enzyme synthesis of nucleic acid metabolites labelled with 14C or 3H are reviewed. Attention is paid namely to the enzyme synthesis methods of radioactive nucleotides of ribonucleic and deoxyribonucleic acids, especially of the nucleoside-5'-triphosphates of adenine, guanine, uracil, cytosine and thymine which are the direct precursors of nucleic acid biosynthesis. Experimental results obtained in the phosphorylation of radioactive nucleoside-5'-monophosphates catalyzed by purified enzyme preparations from Escherichia coli B are summarized. The possibility of the enzyme preparation of radioactive orotidine-5'-monophosphate and uridine-5'-monophosphate is shown on phosphoribosylation of uracil or orotic acid by the catalytic effect of enzymes present in the cell-free extracts of Brevibacterium ammoniagenes. The methods of the enzyme synthesis of radioactive nucleotides of thymine utilizing the properties of thymine-dependent mutants of Escherichia coli are indicated. (author)

67

Coordination polymers of uranium(IV) terephthalates.  

Science.gov (United States)

A series of tetravalent uranium terephthalates has been solvothermally synthesized in the solvent N,N-dimethylformamide (DMF) at temperature 100-150 °C with different water amounts. Composition diagrams have been determined for the U(4+) metallic cation in the presence of terephthalic acid, and their crystal structures revealed the occurrence of two- or three-dimensional coordination polymers. In the absence of water, a mixture of two polytypes T-U(2)Cl(2)(bdc)(3)(DMF)(4) (1) and M-U(2)Cl(2)(bdc)(3)(DMF)(4) (2) has been identified at low temperature (100-110 °C) for bdc/U = 1-4 (bdc = terephthalate linker). Their structures are built up from isolated uranium centers in nine-fold coordination, surrounded by 6 carboxyl oxygen atoms, 2 oxygen atoms coming from DMF molecules and one chlorine atom. The uranium cations are linked to each other through the bdc ligand in order to generate a 3D framework. By increasing the temperature (130-150 °C), a layered like compound has been isolated, U(2)(bdc)(4)(DMF)(4) (3). It is composed of discrete actinide centers in ten-fold coordination, with 8 carboxyl oxygen atoms and 2 oxygen atoms from DMF molecules. The connection of the UO10 units with the bdc linkers generates 2D sheets. When a controlled amount of water is added to the reaction medium, the crystallization of the UiO-66-like U(6)O(4)(OH)(4)(H(2)O)(6)(bdc)(6)·10DMF solid (containing a hexanuclear sub-unit) is observed for temperature 110-120 °C and the H(2)O/U molar ratio in the range of 2-10. At higher temperature (140-150 °C), a distinct phase appeared, U(2)O(2)(bdc)(2)(DMF) (4), which consists of infinite chains of uranium centers, linked to each other via the bdc ligands. Higher water contents led to the formation of urania UO(2). PMID:25428593

Falaise, Clément; Assen, Ayalew; Mihalcea, Ionut; Volkringer, Christophe; Mesbah, Adel; Dacheux, Nicolas; Loiseau, Thierry

2015-02-14

68

Recent synthesis of aminophosphonic acids as potential biological importance.  

Science.gov (United States)

Aminophosphonic acids are an important group of medicinal compounds, and their synthesis has been a focus of considerable attention in synthetic organic chemistry as well as medicinal chemistry. Although the phosphonic and carboxylic acid groups differ considerably with respect to shape, size, and acidity, alpha-aminophosphonic acids are considered to be structural analogues of the corresponding amino acids and the transition state mimics peptide hydrolysis. This review summarizes recent developments in the synthesis, characterization and biological activity of alpha-aminophosphonic acid and N-analogues. An account of both uses will be presented, emphasizing one of the potential future developments, and some implications in medicinal chemistry are also disclosed. In addition, a brief account on the characterization of N-(phosphonomethyl) glycine derivatives will be presented. PMID:19229586

Naydenova, Emilia D; Todorov, Petar T; Troev, Kolio D

2010-01-01

69

?,?-Unsaturated ?,?-diamino acids as building blocks for the asymmetric synthesis of diverse ?,?-diamino acids.  

Science.gov (United States)

A building block approach for the synthesis of ?,?-diamino acids is described, which involves the diastereodivergent preparation of two sets of orthogonally protected ?,?-unsaturated ?,?-diamino acids as templates for the preparation of 12 new ?,?-diamino acids of biological relevance using simple techniques. PMID:25562112

Saha, Nemai; Chatterjee, Bhaskar; Chattopadhyay, Shital K

2015-02-01

70

Inelastic electron tunnelling spectroscopy—III. A study of the molecular orientation of phthalic, isophthalic and terephthalic acids adsorbed on alumina  

Science.gov (United States)

Inelastic electron tunnelling spectroscopy has been employed to determine the molecular orientation of the three benzene dicarboxylic acids on alumina. All three acids are assigned as coordinating to the alumina via one of their carboxyl groups; the non-adsorbed carboxyl group participating in intermolecular hydrogen bonding with its neighbour.

Lewis, D. M.; Field, B. O.

71

Effects of bile acid administration on bile acid synthesis and its circadian rhythm in man  

International Nuclear Information System (INIS)

In man bile acid synthesis has a distinct circadian rhythm but the relationship of this rhythm to feedback inhibition by bile acid is unknown. We measured bile acid synthesis as release of 14CO2 from [26-14C]cholesterol every 2 hr in three normal volunteers during five separate 24-hr periods. Data were fitted by computer to a cosine curve to estimate amplitude and acrophase of the circadian rhythm. In an additional six volunteers, we measured synthesis every 2 hr from 8:00 a.m. to 4:00 p.m. only. During the control period, amplitude (expressed as percentage of mean synthesis) averaged 52% and acrophase averaged 6:49 a.m. During administration of ursodeoxycholic acid (15 mg per kg per day), synthesis averaged 126% of baseline (p less than 0.1), amplitude averaged 43% and acrophase averaged 6:20 a.m. During administration of chenodeoxycholic acid (15 mg per kg per day), synthesis averaged 43% of baseline (p less than 0.001), amplitude averaged 53% and acrophase averaged 9:04 a.m. Addition of prednisone to this regimen of chenodeoxycholic acid to eliminate release of 14CO2 from corticosteroid hormone synthesis resulted in a mean amplitude of 62% and a mean acrophase of 6:50 a.m., values very similar to those in the baseline period. Administration of prednisone alone also did not significantly alter the baseline amplitude (40%) or acrophase (6:28 a.m.). We conclude that neither chenodeoxycholic acid nor ursodeoxycholic acid significantly alters the circadian rhythm of bilicantly alters the circadian rhythm of bile acid synthesis in man

72

Effects of bile acid administration on bile acid synthesis and its circadian rhythm in man  

Energy Technology Data Exchange (ETDEWEB)

In man bile acid synthesis has a distinct circadian rhythm but the relationship of this rhythm to feedback inhibition by bile acid is unknown. We measured bile acid synthesis as release of 14CO2 from (26-14C)cholesterol every 2 hr in three normal volunteers during five separate 24-hr periods. Data were fitted by computer to a cosine curve to estimate amplitude and acrophase of the circadian rhythm. In an additional six volunteers, we measured synthesis every 2 hr from 8:00 a.m. to 4:00 p.m. only. During the control period, amplitude (expressed as percentage of mean synthesis) averaged 52% and acrophase averaged 6:49 a.m. During administration of ursodeoxycholic acid (15 mg per kg per day), synthesis averaged 126% of baseline (p less than 0.1), amplitude averaged 43% and acrophase averaged 6:20 a.m. During administration of chenodeoxycholic acid (15 mg per kg per day), synthesis averaged 43% of baseline (p less than 0.001), amplitude averaged 53% and acrophase averaged 9:04 a.m. Addition of prednisone to this regimen of chenodeoxycholic acid to eliminate release of 14CO2 from corticosteroid hormone synthesis resulted in a mean amplitude of 62% and a mean acrophase of 6:50 a.m., values very similar to those in the baseline period. Administration of prednisone alone also did not significantly alter the baseline amplitude (40%) or acrophase (6:28 a.m.). We conclude that neither chenodeoxycholic acid nor ursodeoxycholic acid significantly alters the circadian rhythm of bile acid synthesis in man.

Pooler, P.A.; Duane, W.C.

1988-09-01

73

Total synthesis of valerenic acid, a potent GABAA receptor modulator.  

Science.gov (United States)

The first total synthesis of the sesquiterpenoid valerenic acid, a constituent of Valeriana officinalis, is described. The compound is a potent modulator of the GABA(A) receptor and may thus be useful in the treatment of various dysfunctions of the central nervous system. The synthesis is enantio-, diastereo-, and regiocontrolled and utilizes an enyne-RCM, a metal-coordinated Diels-Alder reaction, a hydroxy-directed Crabtree hydrogenation, and a Negishi methylation as key steps. PMID:19178294

Ramharter, Jürgen; Mulzer, Johann

2009-03-01

74

Total synthesis of legionaminic Acid as basis for serological studies.  

Science.gov (United States)

Legionaminic acid is a nine-carbon diamino monosaccharide that is found coating the surface of various bacterial human pathogens. Its unique structure makes it a valuable biological probe, but access via isolation is difficult and no practical synthesis has been reported. We describe a stereoselective synthesis that yields a legionaminic acid building block as well as linker-equipped conjugation-ready legionaminic acid starting from cheap d-threonine. To set the desired amino and hydroxyl group pattern of the target, we designed a concise sequence of stereoselective reactions. The key transformations rely on chelation-controlled organometallic additions and a Petasis multicomponent reaction. The legionaminic acid was synthesized in a form that enables attachment to surfaces. Glycan microarray containing legionaminic acid revealed that human antibodies bind the synthetic glycoside. The synthetic bacterial monosaccharide is a valuable probe to detect an immune response to bacterial pathogens such as Legionella pneumophila, the causative agent of Legionnaire's disease. PMID:25668389

Matthies, Stefan; Stallforth, Pierre; Seeberger, Peter H

2015-03-01

75

Involvement of plasmid deoxyribonucleic acid in indoleacetic acid synthesis in Pseudomonas savastanoi.  

OpenAIRE

Olive (or oleander) knot is a plant disease incited by Pseudomonas savastanoi. Disease symptoms consist of tumorous outgrowths induced in the plant by bacterial production of indole-3-acetic acid (IAA). Synthesis of IAA occurs by the following reactions: L-tryptophan leads to indoleacetamide leads to indoleacetic acid, catalyzed by tryptophan 2-monooxygenase and indoleacetamide hydrolase, respectively. Whereas the enzymology of IAA synthesis is well characterized, nothing is known about the g...

Comai, L.; Kosuge, T.

1980-01-01

76

Synthesis of new fatty acids amides from aminolysis of fatty acid methyl esters (FAMEs)  

International Nuclear Information System (INIS)

Recent biochemical and pharmacological studies have led to the characterization of different fatty acid amides as a new family of biologically active lipids. Here, we describe the synthesis of new amides from C16:0, 18:0, 18:1 and 18:1, OH fatty acids (FFA) families with cyclic and acyclic amines and demonstrate for the first time that these compounds produce cytotoxic effects. Application of this method to the synthesis of fatty acid amides was performed using the esters aminolysis as a key step and various carboxylic amides were prepared in good yield from fatty acid methyl esters (FAMEs). (author)

77

High yielding synthesis of N-ethyl dehydroamino acids.  

Science.gov (United States)

Recently we reported the use of a sequence of alkylation and dehydration methodologies to obtain N-ethyl-?, ?-dehydroamino acid derivatives. The application of this N-alkylation procedure to several methyl esters of ?,?-dibromo and ?-bromo, ?-substituted dehydroamino acids protected with standard amine protecting groups was subsequently reported. The corresponding N-ethyl, ?-bromo dehydroamino acid derivatives were obtained in fair to high yields and some were used as substrates in Suzuki cross-coupling reactions to give N-ethyl, ?,?-disubstituted dehydroalanine derivatives. Herein, we further explore N-ethylation of ?-halo dehydroamino acid derivatives using triethyloxonium tetrafluoroborate as alkylating agent, but substituting N,N-diisopropylethylamine for potassium tert-butoxide as auxiliary base. In these conditions, for all ?-halo dehydroamino acid derivatives, reactions were complete and the N-ethylated derivative could be isolated in high yield. This method was also applied for N-ethylation of non-halogenated dehydroamino acids. Again, with all compounds the reactions were complete and the N-ethyl dehydroamino acid derivatives could be isolated in high yields. Some of these N-ethyl dehydroamino acid methyl ester derivatives were converted in high yields to their corresponding acids and coupled to an amino acid methyl ester to give N-ethyl dehydrodipeptide derivatives in good yields. Thus, this method constitutes a general procedure for high yielding synthesis of N-ethylated dehydroamino acids, which can be further applied in peptide synthesis. PMID:22349761

Monteiro, Luís S; Suárez, Ana S

2012-10-01

78

Differential diagnosis in patients with suspected bile acid synthesis defects  

Directory of Open Access Journals (Sweden)

Full Text Available AIM: To investigate the clinical presentations associated with bile acid synthesis defects and to describe identification of individual disorders and diagnostic pitfalls. METHODS: Authors describe semiquantitative determination of 16 urinary bile acid metabolites by electrospray ionization-tandem mass spectrometry. Sample preparation was performed by solid-phase extraction. The total analysis time was 2 min per sample. Authors determined bile acid metabolites in 363 patients with suspected defects in bile acid metabolism. RESULTS: Abnormal bile acid metabolites were found in 36 patients. Two patients had bile acid synthesis defects but presented with atypical presentations. In 2 other patients who were later shown to be affected by biliary atresia and cystic fibrosis the profile of bile acid metabolites was initially suggestive of a bile acid synthesis defect. Three adult patients suffered from cerebrotendinous xanthomatosis. Nineteen patients had peroxisomal disorders, and 10 patients had cholestatic hepatopathy of other cause. CONCLUSION: Screening for urinary cholanoids should be done in every infant with cholestatic hepatopathy as well as in children with progressive neurological disease to provide specific therapy.

Dorothea Haas

2012-01-01

79

Synthesis of imidazol-1-yl-acetic acid hydrochloride: A key intermediate for zoledronic acid  

Directory of Open Access Journals (Sweden)

Full Text Available A convenient and practical synthesis of imidazol-1-yl-acetic acid hydrochloride was achieved via N-alkylation of imidazole using tert-butyl chloroacetate followed by a non-aqueous ester cleavage of the resulting imidazol-1-yl-acetic acid tert-butyl ester in the presence of titanium tetrachloride. The synthesized imidazol-1-yl-acetic acid hydrochloride was then utilized to prepare zoledronic acid.

2008-11-01

80

Synthesis of (2,3-13C2) erucic acid  

International Nuclear Information System (INIS)

The synthesis of (13C) erucic acid, for use in metabolic studies, is reported. The synthesis employs a repeated 3 step reaction sequence using 13C labeled triethylphosphonoacetate to extend C18:1, oleyl alcohol, by 4 carbons. The (13C) erucic acid, obtained by hydrolysis with alcoholic KOH, gave 13C NMR signals of ? 24.6 and 34.1 ppm for C-3 and C-2 respectively with a J = 34.9 Hz. The overall yield was 5.5%. (author)

81

Comparison of bile acid synthesis determined by isotope dilution versus fecal acidic sterol output in human subjects  

International Nuclear Information System (INIS)

Fecal acidic sterol output has been found to be much lower than bile acid synthesis determined by isotope dilution. Because of this confusing discrepancy, we compared these 2 measurements done simultaneously on 13 occasions in 5 normal volunteers. In contrast to previous findings, bile acid synthesis by the Lindstedt isotope dilution method averaged 16.3% lower than synthesis simultaneously determined by fecal acidic sterol output (95% confidence limit for the difference - 22.2 to -10.4%). When one-sample determinations of bile acid pools were substituted for Lindstedt pools, bile acid synthesis by isotope dilution averaged 5.6% higher than synthesis by fecal acidic sterol output (95% confidence limits -4.9 to 16.1%). These data indicate that the 2 methods yield values in reasonably close agreement with one another. If anything, fecal acidic sterol outputs are slightly higher than synthesis by isotope dilution

82

Selective Synthesis of Citric Acid from Molasses using Aspergillus Niger  

OpenAIRE

Selective synthesis of Citric Acid from local cane molasses using Aspergillus niger was studied. A local stain of A.niger isolated from lemon tree leaves & cultured. A.niger stain ATCC-595 were separately studied for the Bioconversion of local molasses into citric acid. The molasses fermentation was carried out at 30°C in a flask. The results showed increased efficiency for citric acid production when compared with wild type. It produced 210.12 gm/lit of citric acid as compared to wild stain...

Pohnerkar, Jayant K.; Desai, S. A.

2014-01-01

83

Synthesis of itaconic acid from the irradiation of aconitic acid-clay suspensions  

International Nuclear Information System (INIS)

The radiolysis of aconitic acid in aqueous solution and in water-clay suspensions was studied. Among the radiolytic products, itaconic acid (HO2C-C(=CH2)-CH2CO2H) was formed. Itaconic acid is a valuable monomer in the formulation of polymers. The synthesis of itaconic acid can be achieved in one step using aqueous solutions of aconitic acid and in water-clay suspensions exposed to ionizing radiation. The yield of formation does not compete with fermentation procedures for the synthesis of itaconic acid, but for laboratory purposes is a very simple method to prepare it. Other products of the radiolysis were carbon dioxide, tricarballylic and citric/isocitric acids. (Author)

84

Copper-catalyzed aerobic oxidative synthesis of aromatic carboxylic acids.  

Science.gov (United States)

A simple, practical and efficient copper-catalyzed method for synthesis of aromatic carboxylic acids has been developed. The protocol uses inexpensive CuI/L-proline as the catalyst/ligand, and readily available aryl halides and malononitrile as the starting materials, and the corresponding aromatic carboxylic acids were obtained in moderate to good yields. The method is of tolerance towards functional groups in the substrates. PMID:21152586

Yang, Daoshan; Yang, Haijun; Fu, Hua

2011-02-28

85

Synthesis of [14CO]ellagic acid  

International Nuclear Information System (INIS)

[14CO]Ellagic acid with a chemical purity of 98.9% and radiochemical purity of 99.9% was synthesized with an overall yield of 16% (both chemically and radiochemically). Reaction of 14CO2 with lithiated 3,4,5-trimethoxybenzene and demethylation of the resulting 3,4,5-trimethoxybenzoic acid was followed by esterification and coupling of methyl gallate into ellagic acid. Two efficient coupling methods were employed: direct aeration and aeration of methyl gallate in the presence of the phenolic oxidase, tyrosinase. The latter method produced the highest yield and purity. This preparation produced [14CO]ellagic acid with a specific activity of 20 mCi/mmol. The yields of labeled 3,4,5-trimethoxybenzoic acid and ellagic acid based on Ba14CO3 were 65% and 16%, respectively. (author)

86

Cancer chemotherapy: targeting folic acid synthesis  

OpenAIRE

Nicole Hagner, Markus JoergerDepartment of Medical Oncology, Cantonal Hospital, St Gallen, SwitzerlandAbstract: Antifolates are structural analogs of folates, essential one-carbon donors in the synthesis of DNA in mammalian cells. Antifolates are inhibitors of key enzymes in folate metabolism, namely dihydrofolate reductase, ?-glycinamide ribonucleotide transformylase, 5'-amino-4'-imidazolecarboxamide ribonucleotide transformylase, and thymidylate synthetase. Methotre...

Nicole Hagner; Markus Joerger

2010-01-01

87

Synthesis of amorphous acid iron phosphate nanoparticles  

International Nuclear Information System (INIS)

A simple method to precipitate nanoparticles of iron phosphate with acid character has been developed in which the control of pH allows to obtain amorphous nanoparticles. The acid aging of the precipitated amorphous nanoparticles favored the P–O bond strength that contributes to the surface reordering, the surface roughness and the increase of the phosphate acid character. The thermal behavior of the acid iron phosphate nanoparticles has been also studied and the phosphate polymerization at 400 °C produces strong compacts of amorphous nanoparticles with interconnected porosity.

88

Lewis acid-catalysed one pot synthesis of substituted xanthenes.  

Science.gov (United States)

A direct synthesis of substituted xanthenes from salicylaldehydes and cyclohexenones or tetralones has been developed. The reaction is catalysed by Lewis acids like scandium triflate and furnishes substituted xanthenes in good to excellent yields using either microwave or thermal heating. Microwave heating results in significantly shortened reaction times of 30 min and generally higher yields. PMID:21253655

Böss, Esther; Hillringhaus, Tim; Nitsch, Jacqueline; Klussmann, Martin

2011-03-21

89

Modificação química de poli(tereftalato de etileno pós-consumo por reação com ácido sulfúrico: estrutura e propriedades Chemical modification of post consumer poly(ethylene terephthalate by sulfuric acid reaction: structure and properties  

Directory of Open Access Journals (Sweden)

Full Text Available PET pós-consumo foi modificado quimicamente através de reação com ácido sulfúrico por diferentes tempos. O material modificado foi caracterizado por DSC e FTIR-PAS e XPS. Verificou-se que a intensidade relativa do isômero trans diminui enquanto do isômero gauche aumenta para tempos de reação entre 0 e 60 minutos. Após 60 minutos de reação observou-se a presença de endotermas múltiplas que podem ser relacionadas com o desenvolvimento de estruturas intermediárias porque as intensidades relativas dos isômeros trans e gauche não apresentam variação significativa. O valor determinado de capacidade de troca iônica do PET pós-consumo modificado (PETS-pc é comparável com os valores de resinas ácidas comerciais e não é afetado no intervalo de tempo de reação utilizado. Os valores da capacidade máxima de adsorção, qm, e do parâmetro de afinidade entre o adsorvente e o adsorvato, K, (111,18 ppm e 531,91 mg de corante/100g de adsorvente, respectivamente para a adsorção do corante Remazol vermelho na amostra quimicamente modificada por 30 minutos foram calculados a partir da isoterma de adsorção de Langmuir. Os resultados indicam que esse material possui características adsorventes, podendo vir a ser utilizado para tratamento de efluente de indústria de tingimento têxtil.Chemical modification of post consumer PET was carried out by reaction with sulfuric acid. The modified material was characterized by DSC, XPS and FTIR-PAS measurements. The relative intensity of trans isomer increases while it decreases for gauche isomer for reaction times from 0 up to 60 min. After 60 minutes of reaction multiple endotherms were observed, which may be related to the development of an intermediated structure, since the relative intensities of the trans and gauche isomers do not change. The ionic exchange capacity of the modified post consumer poly(ethylene terephthalate, PETS-pc, is comparable to commercial acid resins and is not affected by the reaction time. The maximum adsorption capacity, qm, and the affinity parameter, K, (111.18 ppm and 531.91 mg dye/100g adsorvent, respectively due to the adsorption of Remazol Red were calculated for PET samples chemically modified during 30 minutes from the Langmuir adsorption isotherms. The results indicate that PETS-pc has excellent adsorvent capacity, and can be applied to treatment of textile dye effluents.

Janaína G. Alonso

2005-03-01

90

Modificação química de poli(tereftalato de etileno) pós-consumo por reação com ácido sulfúrico: estrutura e propriedades / Chemical modification of post consumer poly(ethylene terephthalate) by sulfuric acid reaction: structure and properties  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese PET pós-consumo foi modificado quimicamente através de reação com ácido sulfúrico por diferentes tempos. O material modificado foi caracterizado por DSC e FTIR-PAS e XPS. Verificou-se que a intensidade relativa do isômero trans diminui enquanto do isômero gauche aumenta para tempos de reação entre 0 [...] e 60 minutos. Após 60 minutos de reação observou-se a presença de endotermas múltiplas que podem ser relacionadas com o desenvolvimento de estruturas intermediárias porque as intensidades relativas dos isômeros trans e gauche não apresentam variação significativa. O valor determinado de capacidade de troca iônica do PET pós-consumo modificado (PETS-pc) é comparável com os valores de resinas ácidas comerciais e não é afetado no intervalo de tempo de reação utilizado. Os valores da capacidade máxima de adsorção, qm, e do parâmetro de afinidade entre o adsorvente e o adsorvato, K, (111,18 ppm e 531,91 mg de corante/100g de adsorvente, respectivamente) para a adsorção do corante Remazol vermelho na amostra quimicamente modificada por 30 minutos foram calculados a partir da isoterma de adsorção de Langmuir. Os resultados indicam que esse material possui características adsorventes, podendo vir a ser utilizado para tratamento de efluente de indústria de tingimento têxtil. Abstract in english Chemical modification of post consumer PET was carried out by reaction with sulfuric acid. The modified material was characterized by DSC, XPS and FTIR-PAS measurements. The relative intensity of trans isomer increases while it decreases for gauche isomer for reaction times from 0 up to 60 min. Afte [...] r 60 minutes of reaction multiple endotherms were observed, which may be related to the development of an intermediated structure, since the relative intensities of the trans and gauche isomers do not change. The ionic exchange capacity of the modified post consumer poly(ethylene terephthalate), PETS-pc, is comparable to commercial acid resins and is not affected by the reaction time. The maximum adsorption capacity, qm, and the affinity parameter, K, (111.18 ppm and 531.91 mg dye/100g adsorvent, respectively) due to the adsorption of Remazol Red were calculated for PET samples chemically modified during 30 minutes from the Langmuir adsorption isotherms. The results indicate that PETS-pc has excellent adsorvent capacity, and can be applied to treatment of textile dye effluents.

Janaína G., Alonso; Elisabeth C., Molina; Edvani C., Muniz; Adley F., Rubira; Gizilene M. de, Carvalho.

2005-03-01

91

Synthesis of gold nanoparticles using various amino acids.  

Science.gov (United States)

Gold nanoparticles (4-7nm) were synthesized from tetraauric acid using various amino acids as reducing and capping agents. The gold nanoparticles were produced from the incubation of a AuCl4(-) solution with an amino acid at 80°C for 20min. Among the twenty amino acids tested, several amino acids produced gold nanoparticles. The color of the nanoparticle solutions varied with the amino acids used for the reduction. We adopted l-histidine as a reducing agent and investigated the effects of the synthesis conditions on the gold nanoparticles. The His and AuCl4(-) concentrations affected the size of the gold nanoparticles and their aggregates. The pH of the reaction solution also affected the reaction yields and the shape of the gold nanoparticles. PMID:25591824

Maruyama, Tatsuo; Fujimoto, Yuhei; Maekawa, Tetsuya

2015-06-01

92

Stereoselective synthesis of stable-isotope-labeled amino acids  

Energy Technology Data Exchange (ETDEWEB)

For magnetic resonance and vibrational spectroscopies to reach their full potential, they must be used in combination with sophisticated site-specific stable isotope labeling of biological macromolecules. Labeled amino acids are required for the study of the structure and function of enzymes and proteins. Because there are 20 common amino acids, each with its own distinguishing chemistry, they remain a synthetic challenge. The Oppolzer chiral auxiliary provides a general tool with which to approach the synthesis of labeled amino acids. By using the Oppolzer auxiliary, amino acids can be constructed from several small molecules, which is ideal for stable isotope labeling. In addition to directing the stereochemistry at the {alpha}-carbon, the camphorsultam can be used for stereo-specific isotope labeling at prochiral centers in amino acids. By using the camphorsultam auxiliary we have the potential to synthesize virtually any isotopomer of all of the common amino acids.

Unkefer, C.J.; Martinez, R.A.; Silks, L.A. III [Los Alamos National Laboratory, NM (United States); Lodwig, S.N. [Centralia College, WA (United States)

1994-12-01

93

Selective Synthesis of Citric Acid from Molasses using Aspergillus Niger  

Directory of Open Access Journals (Sweden)

Full Text Available Selective synthesis of Citric Acid from local cane molasses using Aspergillus niger was studied. A local stain of A.niger isolated from lemon tree leaves & cultured. A.niger stain ATCC-595 were separately studied for the Bioconversion of local molasses into citric acid. The molasses fermentation was carried out at 30°C in a flask. The results showed increased efficiency for citric acid production when compared with wild type. It produced 210.12 gm/lit of citric acid as compared to wild stain 102.5 gm/lit. The maximum citric acid production is on the 9th day of fermentation by used stain and 11th day by the wild type. This investigation is one of the ecofriendly technology can be used for economic development & environmental protection in india. By recycling & reusing waste material from cane Industries Citric acid production can be easily done.

Jayant.K.Pohnerkar

2014-03-01

94

Synthesis and Characterization of Fatty Acid/Amino Acid Self-Assemblies  

OpenAIRE

In this paper, we discuss the synthesis and self-assembling behavior of new copolymers derived from fatty acid/amino acid components, namely dimers of linoleic acid (DLA) and tyrosine derived diphenols containing alkyl ester pendent chains, designated as “R” (DTR). Specific pendent chains were ethyl (E) and hexyl (H). These poly(aliphatic/aromatic-ester-amide)s were further reacted with poly(ethylene glycol) (PEG) and poly(ethylene glycol methyl ether) of different molecular masses, thus ...

Joanna Gajowy; Durgadas Bolikal; Joachim Kohn; Miroslawa El Fray

2014-01-01

95

Photolabile linker for the synthesis of hydroxamic acids  

DEFF Research Database (Denmark)

The present invention relates to a photolabile hydroxamate linker based on the o - nitroveratryl group and its application for multistep solid-phase synthesis and controlled photolytic release of hydroxamic acids. The invention provides a method for producing a solid support comprising a hydroxylamine - functionalized photolabile linker, and the so produced hydroxylamine - functionalized photolabile solid support. The invention further provides a method for synthesizing a one-bead-one compound library of hydroxamic acid derivatives on a photolabile linker, as well as a method for screening a library of hydroxamic acid derivatives.

Nielsen, Thomas Eiland Technical University of Denmark,

96

On synthesis of silicoaluminotungstic heteropoly acid  

International Nuclear Information System (INIS)

A possibility to preparation of silicoaluminotungstic heteropoly acid using 183W and 27Al NMR method was investigated. Heteropoly acid H5SiW11Al(H2O)O39 is made by two methods: ether extraction and by means of electrodialysis in double-chamber apparatus with semipermeable membrane from cation-exchange resin. Concentrated aqueous solution containing heteropoly acid based on SiW11Al(H2O)O395- anion with impurity of 15 % H4SiW12O40 was obtained by electrodialysis. Conducted study revealed that heteropoly acid H5SiW11Al(H2O)O39 (or its based oligomer) may be prepared as not stable (to heating and prolonged endurance) aqueous solution, other than solid form

97

Pyrenylamino acids : synthesis, photophysical and electrochemical studies  

OpenAIRE

Several beta-pyrenyldehydroamino acids and a pyrenylalanine derivative were synthesized in good to high yields from dehydroamino acids using several types of reactions. A beta-[(pyren-1-yl)methylamino]alanine was prepared treating the methyl ester of N,N-(di-tert-butoxycarbonyl)dehydroalanine with 1-pyrenemethylamine hydrochloride in the presence of an excess of potassium carbonate. The methyl esters of N-(tert-butoxycarbonyl)-beta-(1,2,4-triazol-1-yl) dehydroalanine and dehydroaminobutyric a...

Abreu, Ana S.; Castanheira, Elisabete M. S.; Ferreira, Paula M. T.; Monteiro, Lui?s S.; Pereira, Goreti; Queiroz, Maria Joa?o R. P.

2008-01-01

98

Synthesis of novel adamantyl and homoadamantyl-substituted ?-hydroxybutyric acids.  

Science.gov (United States)

Several new adamantyl and homoadamantyl-substituted [Formula: see text]-hydroxybutyric acids, 2-[2-(1-adamantyl)ethyl]-3-hydroxybutyric acid (2), 2-(3-homoadamantyl)-3-hydroxybutyric acid (3), and 2-(1-homoadamantyl)-3-hydroxybutyric acid (4), analogues of the 2-(1-adamantyl)-3-hydroxybutyric acid (1), have been prepared as mixtures of diastereoisomers using selective reduction of corresponding [Formula: see text]-keto esters or aldol condensation of the corresponding carboxylic acid and acetaldehyde. The rearrangement of adamantylmethyl and 3-homoadamantyl groups provided entry to both 3-homoadamantyl and 1-homoadamantyl-substituted hydroxy acids 3 and 4, respectively. The relative configurations of diastereoisomers 3 and 4 have been determined by NMR spectroscopy comparing the values of coupling constants. Adamantyl-substituted [Formula: see text]-hydroxybutyric acid 2 has also been prepared in enantiomerically pure form by Evan's asymmetric synthesis and the absolute configuration has been determined by X-ray crystallography. Contrary to the long-chain acid 2, the attempt to prepare short-chain hydroxy acids 1 and 4 by the same method failed indicating pronounced sensitivity of the used method to the vicinity of the bulky cage group. PMID:24043584

Matkovi?, Marija; Vukeli?, Stella; Cirimoti?, Ružica; Kragol, Goran; Mol?anov, Krešimir; Mlinari?-Majerski, Kata

2013-11-01

99

Role of Ferrocyanides in the Prebiotic Synthesis of ?-Amino Acids  

Science.gov (United States)

We investigated the synthesis of ?-amino acids under possible prebiotic terrestrial conditions in the presence of dissolved iron (II) in a simulated prebiotic ocean. An aerosol-liquid cycle with a prebiotic atmosphere is shown to produce amino acids via Strecker synthesis with relatively high yields. However, in the presence of iron, the HCN was captured in the form of a ferrocyanide, partially inhibiting the formation of amino acids. We showed how HCN captured as Prussian Blue (or another complex compound) may, in turn, have served as the HCN source when exposed to UV radiation, allowing for the sustained production of amino acids in conjunction with the production of oxyhydroxides that precipitate as by-products. We conclude that ferrocyanides and related compounds may have played a significant role as intermediate products in the prebiotic formation of amino acids and oxyhydroxides, such as those that are found in iron-containing soils and that the aerosol cycle of the primitive ocean may have enhanced the yield of the amino acid production.

Ruiz-Bermejo, Marta; Osuna-Esteban, Susana; Zorzano, María-Paz

2013-06-01

100

Synthesis of an enantiopure isoxazolidine monomer for ?3-aspartic acid in chemoselective ?-oligopeptide synthesis  

Science.gov (United States)

The synthesis of an enantiopure isoxazolidine monomer for the incorporation of ?3-apartic acid residues into ?3-oligopeptides via chemoselective ?-ketoacid–hydroxylamine amide formation. This route involves nitrone cycloaddition of 3-thiophenylpropanal and circumvents limitations of other potential starting materials PMID:20161312

Ishida, Hiroshi; Carrillo, Nancy; Bode, Jeffrey W.

2009-01-01

101

Synthesis of an enantiopure isoxazolidine monomer for ?3-aspartic acid in chemoselective ?-oligopeptide synthesis  

OpenAIRE

The synthesis of an enantiopure isoxazolidine monomer for the incorporation of ?3-apartic acid residues into ?3-oligopeptides via chemoselective ?-ketoacid–hydroxylamine amide formation. This route involves nitrone cycloaddition of 3-thiophenylpropanal and circumvents limitations of other potential starting materials

Ishida, Hiroshi; Carrillo, Nancy; Bode, Jeffrey W.

2009-01-01

102

Inhibition of RNA synthesis by oxolinic acid is unrelated to average DNA supercoiling.  

OpenAIRE

Oxolinic acid reduced RNA synthesis rates whether chromosome supercoiling decreased, increased, or remained unchanged. Thus, inhibition of RNA synthesis by oxolinic acid appears to involve factors other than average DNA supercoiling level. Coumermycin A1 caused RNA synthesis rates to increase or decrease roughly in parallel with DNA supercoiling.

Manes, S. H.; Pruss, G. J.; Drlica, K.

1983-01-01

103

Synthesis of azido derivatives of mucobromic acid  

Directory of Open Access Journals (Sweden)

Full Text Available Mucobromic acid is a highly reactive multicentered molecule. It was converted to its corresponding but unstable diazido derivative by reaction with two equivalents of sodium azide. The resultant 3,4-diazido-5-hydroxyfuran-2(5H-one was obtained in moderate yield (42% but decomposed readily even at low temperatures. Its more stable analogue 3,4-diazido-5-methoxyfuran-2(5H-one was obtained in excellent yield after reacting 5-methoxy-3,4-dibromofuranone with two equivalents of sodium azide. The 4,5-dibromopyridazinones which are in effect masked mucobromic acid derivatives, underwent nucleophilic substitution reactions with various nucleophiles, including azides and afforded corresponding azidopyridazinones in good yields. The synthesized azido-furanone and pyridazinone derivatives are earmarked for click reactions.DOI: http://dx.doi.org/10.4314/bcse.v27i1.17

N. Mbebe

2013-04-01

104

Fatty acid effects on fibroblast cholesterol synthesis  

Energy Technology Data Exchange (ETDEWEB)

Two cell lines of normal (CRL 1475, GM5565) and of familial hypercholesterolemia (FH) (CM 486,488) fibroblasts were preincubated with medium containing the growth factor ITS, 2.5 mg/ml fatty acid-free BSA, or 35.2 ..mu..mol/ml of these fatty acids complexed with 2.5 mg BSA/ml: stearic (18:0), caprylic (8:0), oleic (18:1;9), linoleic (18:2;9,12), linolenic (18:3;9,12,15), docosahexaenoic (22:6;4,7,10,13,16,19)(DHA) or eicosapentaenoic (20:5;5,8,11,14,17)(EPA). After 20 h, cells were incubated for 2 h with 0.2 ..mu..Ci (/sup 14/C)acetate/ml. Cells were hydrolyzed; an aliquot was quantitated for radioactivity and protein. After saponification and extraction with hexane, radioactivity in the aqueous and organic phases was determined. The FH cells always incorporated 30-90% more acetate/mg protein than normal cells but the pattern of the fatty acid effects was similar in both types. When the values were normalized to 1 for the BSA-only group, cells with ITS had the greatest (/sup 14/C)acetate incorporation (1.45) followed by the caprylic group (1.14). Cells incubated with 18:3, 20:6 or 22:6 incorporated about the same amount as BSA-only. Those preincubated with 18:2, 18:1, 18:0 showed the least acetate incorporation (0.87, 0.59 and 0.52, respectively). The percentage of total /sup 14/C counts which extracted into hexane was much greater in FH cells; however, these values varied with the fatty acid, e.g., 1.31(18:0) and 0.84(8:0) relative to 1(BSA).

Shireman, R.B.; Muth, J.; Lopez, C.

1987-05-01

105

Fatty acid synthesis: from CO2 to functional genomics.  

Science.gov (United States)

For over 25 years there has been uncertainty over the pathway from CO(2) to acetyl-CoA in chloroplasts. On the one hand, free acetate is the most effective substrate for fatty acid synthesis by isolated chloroplasts, and free acetate concentrations reported in leaf tissue (0.1-1 mM) appear adequate to saturate fatty acid synthase. On the other hand, a clear mechanism to generate sufficient free acetate for fatty acid synthesis is not established and direct production of acetyl-CoA from pyruvate by a plastid pyruvate dehydrogenase seems a more simple and direct path. We have re-examined this question and attempted to distinguish between the alternatives. The kinetics of (13)CO(2) and (14)CO(2) movement into fatty acids and the absolute rate of fatty acid synthesis in leaves was determined in light and dark. Because administered (14)C appears in fatty acids within 50% oil whereas other seeds store largely carbohydrate or protein. Major control over complex plant biochemical pathways may only become possible by understanding regulatory networks which provide 'global' control over these pathways. To begin to discover such networks and provide a broad analysis of gene expression in developing oilseeds, we have produced microarrays that display approx. 5000 seed-expressed Arabidopsis genes. Sensitivity of the arrays was 1-2 copies of mRNA/cell. The arrays have been hybridized with probes derived from seeds, leaves and roots, and analysis of expression ratios between the different tissues has allowed the tissue-specific expression patterns of many hundreds of genes to be described for the first time. Approx. 10% of the genes were expressed at ratios > or = 10-fold higher in seeds than in leaves or roots. Included in this list are a large number of proteins of unknown function, and potential regulatory factors such as protein kinases, phosphatases and transcription factors. The arrays were also found to be useful for analysis of Brassica seeds. PMID:11171129

Ohlrogge, J; Pollard, M; Bao, X; Focke, M; Girke, T; Ruuska, S; Mekhedov, S; Benning, C

2000-12-01

106

Lipoic acid synthesis and attachment in yeast mitochondria.  

Science.gov (United States)

Lipoic acid is a sulfur-containing cofactor required for the function of several multienzyme complexes involved in the oxidative decarboxylation of alpha-keto acids and glycine. Mechanistic details of lipoic acid metabolism are unclear in eukaryotes, despite two well defined pathways for synthesis and covalent attachment of lipoic acid in prokaryotes. We report here the involvement of four genes in the synthesis and attachment of lipoic acid in Saccharomyces cerevisiae. LIP2 and LIP5 are required for lipoylation of all three mitochondrial target proteins: Lat1 and Kgd2, the respective E2 subunits of pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase, and Gcv3, the H protein of the glycine cleavage enzyme. LIP3, which encodes a lipoate-protein ligase homolog, is necessary for lipoylation of Lat1 and Kgd2, and the enzymatic activity of Lip3 is essential for this function. Finally, GCV3, encoding the H protein target of lipoylation, is itself absolutely required for lipoylation of Lat1 and Kgd2. We show that lipoylated Gcv3, and not glycine cleavage activity per se, is responsible for this function. Demonstration that a target of lipoylation is required for lipoylation is a novel result. Through analysis of the role of these genes in protein lipoylation, we conclude that only one pathway for de novo synthesis and attachment of lipoic acid exists in yeast. We propose a model for protein lipoylation in which Lip2, Lip3, Lip5, and Gcv3 function in a complex, which may be regulated by the availability of acetyl-CoA, and which in turn may regulate mitochondrial gene expression. PMID:19570983

Schonauer, Melissa S; Kastaniotis, Alexander J; Kursu, V A Samuli; Hiltunen, J Kalervo; Dieckmann, Carol L

2009-08-28

107

Synthesis of Bosutinib from 3-Methoxy-4-hydroxybenzoic Acid  

Directory of Open Access Journals (Sweden)

Full Text Available This paper reports a novel synthesis of bosutinib starting from 3-methoxy-4-hydroxybenzoic acid. The process starts with esterification of the starting material, followed by alkylation, nitration, reduction, cyclization, chlorination and two successive amination reactions. The intermediates and target molecule were characterized by 1H-NMR, 13C-NMR, MS and the purities of all the compounds were determined by HPLC.

Xiao Jia Yin

2010-06-01

108

Is acetylcarnitine a substrate for fatty acid synthesis in plants  

Energy Technology Data Exchange (ETDEWEB)

Long-chain fatty acid synthesis from [1-[sup 14]C]acetylcarnitine by chloroplasts isolated from spinach (Spinacia oleracea), pea (Pisum sativum), amaranthus (Amaranthus lividus), or maize (Zea mays) occurred at less than 2% of the rate of fatty acid synthesis from [1-[sup 14]C]acetate irrespective of the maturity of the leaves or whether the plastids were purified using sucrose or Percoll medium. [1-[sup 14]C]Acetylcarnitine was not significantly utilized by highly active chloroplasts rapidly prepared from pea and spinach using methods not involving density gradient centrifugation. [1-[sup 14]C]Acetylcarnitine was recovered quantitatively from chloroplast incubations following 10 min in the light. Unlabeled acetyl-L-carnitine (0.4 mM) did not compete with [1-[sup 14]C]acetate (0.2 mM) as a substrate for fatty acid synthesis by any of the more than 70 chloroplast preparations tested in this study. Carnitine acetyltransferase activity was not detected in any chloroplast preparation and was present in whole leaf homogenates at about 0.1% of the level of acetyl-coenzyme A synthetase activity. When supplied to detached pea shoots and detached spinach, amaranthus, and maize leaves via the transpiration stream, 1 to 4% of the [1-[sup 14]C]acetylcarnitine and 47 to 57% of the [1-[sup 14]C]acetate taken up was incorporated into lipids. Most (78--82%) of the [1-[sup 14]C]acetylcarnitine taken up was recovered intact. It is concluded that acetylcarnitine is not a major precursor for fatty acid synthesis in plants. 29 refs., 5 tabs.

Roughan, G. (Horticulture Research Inst., Auckland (New Zealand)); Post-Beittenmiller, D.; Ohlrogge, J. (Michigan State Univ., East Lansing (United States)); Browse, J. (Washington State Univ., Pullman (United States))

1993-04-01

109

SYNTHESIS OF HYDROGELS CONTAINING INDOLBUTYRIC ACID AS ROOTING AUXIN  

Scientific Electronic Library Online (English)

Full Text Available This article is devoted to the synthesis and characterization of acrylamide-acrylic acid hydrogels containing indolbutyric acid (IBA) as rooting auxin by two different methods. In the first alternative, the hormone is incorporated in the reagents mixture before polymerization, and in the second one, [...] IBA become incorporated through a dry hydrogel hydration in a hormone ethanol-water solution. In both cases the quantity of IBA incorporated to the gel is determined and interrelated with IBA concentration in the mixtures and solutions

DIETER, KLATTENHOFF; RENE, ESCOBAR; EDUARDO, ALISTE.

2006-06-01

110

Microwave-Promoted synthesis of novel N-Arylanthranilic acids  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Nesse trabalho é relatada a síntese de uma série de ácidos N-aril antranílicos inéditos, com bons a excelentes rendimentos, empregando irradiação de microondas como fonte de aquecimento para promover a reação de acoplamento de Ullmann entre ácidos antranílicos e brometos de arila contendo grupos sub [...] stituintes doadores ou aceptores de elétrons. Abstract in english In this paper we report the synthesis of a series of novel N-aryl anthranilic acids, with good to excellent yields, employing microwaves as heat source to promote the Ullmann coupling between anthranilic acids and aryl bromides possessing electron donating or withdrawing groups. [...

Mauro A., Bueno; Larissa R. S. P., Silva; Arlene G., Corrêa.

1264-12-01

111

Cancer chemotherapy: targeting folic acid synthesis  

Directory of Open Access Journals (Sweden)

Full Text Available Nicole Hagner, Markus JoergerDepartment of Medical Oncology, Cantonal Hospital, St Gallen, SwitzerlandAbstract: Antifolates are structural analogs of folates, essential one-carbon donors in the synthesis of DNA in mammalian cells. Antifolates are inhibitors of key enzymes in folate metabolism, namely dihydrofolate reductase, ?-glycinamide ribonucleotide transformylase, 5'-amino-4'-imidazolecarboxamide ribonucleotide transformylase, and thymidylate synthetase. Methotrexate is one of the earliest anticancer drugs and is extensively used in lymphoma, acute lymphoblastic leukemia, and osteosarcoma, among others. Pemetrexed has been approved in combination with cisplatin as first-line treatment for advanced non-squamous-cell lung cancer, as a single agent for relapsed non-small-cell lung cancer after platinum-containing chemotherapy, and in combination with cisplatin for the treatment of pleural mesothelioma. Raltitrexed is approved in many countries (except in the United States for advanced colorectal cancer, but its utilization is mainly limited to patients intolerant to 5-fluorouracil. Pralatrexate has recently been approved in the United States for relapsed or refractory peripheral T-cell lymphoma. This article gives an overview of the cellular mechanism, pharmacology, and clinical use of classical and newer antifolates and discusses some of the main resistance mechanisms to antifolate drugs.Keywords: antifolates, cancer, molecular pharmacology, pemetrexed, methotrexate, folate metabolism

Nicole Hagner

2010-11-01

112

Synthesis and properties of alumosilicotungstic acid  

International Nuclear Information System (INIS)

The saturation method was used to study the interaction of aluminium nitrate with potassium It is shown that a silicoalumotungstic complex is formed with ratio Al:SiW11=1:1. There have been synthesized silicotungstic acid and its sodium, potassium and cesium salts, of the following composition: H5[SiAlW11O39xH2O]x14H2O; Na5[SiAlW11O39xH2O]x14H2O; K5[SiAlW11O39xH2O]x12H2O; Cs5[SiAlW11O39xH2O]x8H2O. Potentiometric titration of the aqueous solutions of the acid has shown that it is pentabasic: H5[SiAlW11O39xH2O]x14H2O. The absorption spectra of the resulting compounds have a maximum at 260 nm

113

Inhibition of fatty acid synthesis in rat hepatocytes by exogenous polyunsaturated fatty acids is caused by lipid peroxidation  

DEFF Research Database (Denmark)

Rat hepatocyte long-term cultures were utilized to investigate the impact of different polyunsaturated fatty acids (PUFA) on the insulin-induced de novo fatty acid synthesis in vitro. The addition of 0.5 mM albumin-complexed oleic, linoleic, columbinic, arachidonic, eicosapentaenoic or docosahexaenoic acid resulted in a marked suppression of fatty acid synthesis. By evaluation of cell viability (determined as the leakage of lactate dehydrogenase (LDH)) it turned our, that the antioxidant used (50 µM a-tocopherol phosphate) had a low antioxidant activity, resulting in cytotoxic effects by the peroxidized PUFA. Arachidonic acid and eicosapentaenoic acid showed a dose- and time-dependent cytotoxicity. Two other antioxidants: 50 µM a-tocopherol acid succinate and 1 µM N,N'-diphenyl-1,4-phenylenediamine, both proved more efficient than a-tocopherol phosphate. There was a significant correlation between LDH-leakage and inhibition of fatty acid synthesis. Lipid peroxidation, measured as thiobarbituric acid-reactive substances, also showed a significant correlation with the degree of inhibition of fatty acid synthesis. Furthermore, PUFA had no inhibitory effect on fatty acid synthesis when peroxidation was minimized by the use of proper antioxidants. These data indicate that PUFA in vitro inhibit the insulin-induced de novo fatty acid synthesis in hepatocytes from starved rats, due to cytotoxic effects caused by lipid peroxidation.

Mikkelsen, L.; Hansen, Harald S.

1993-01-01

114

Biotin and Lipoic Acid: Synthesis, Attachment and Regulation  

Science.gov (United States)

Summary Two vitamins, biotin and lipoic acid, are essential in all three domains of life. Both coenzymes function only when covalently attached to key metabolic enzymes. There they act as “swinging arms” that shuttle intermediates between two active sites (= covalent substrate channeling) of key metabolic enzymes. Although biotin was discovered over 100 years ago and lipoic acid 60 years ago, it was not known how either coenzyme is made until recently. In Escherichia coli the synthetic pathways for both coenzymes have now been worked out for the first time. The late steps of biotin synthesis, those involved in assembling the fused rings, were well-described biochemically years ago, although recent progress has been made on the BioB reaction, the last step of the pathway in which the biotin sulfur moiety is inserted. In contrast, the early steps of biotin synthesis, assembly of the fatty acid-like “arm” of biotin were unknown. It has now been demonstrated that the arm is made by using disguised substrates to gain entry into the fatty acid synthesis pathway followed by removal of the disguise when the proper chain length is attained. The BioC methyltransferase is responsible for introducing the disguise and the BioH esterase for its removal. In contrast to biotin, which is attached to its cognate proteins as a finished molecule, lipoic acid is assembled on its cognate proteins. An octanoyl moiety is transferred from the octanoyl-ACP of fatty acid synthesis to a specific lysine residue of a cognate protein by the LipB octanoyl transferase followed by sulfur insertion at carbons C6 and C8 by the LipA lipoyl synthetase. Assembly on the cognate proteins regulates the amount of lipoic acid synthesized and thus there is no transcriptional control of the synthetic genes. In contrast transcriptional control of the biotin synthetic genes is wielded by a remarkably sophisticated, yet simple, system, exerted through BirA a dual function protein that both represses biotin operon transcription and ligates biotin to its cognate protein. PMID:25414908

Cronan, John E.

2014-01-01

115

Biphasic effect of oleic acid on hepatic cholesterol synthesis  

International Nuclear Information System (INIS)

The authors observed previously that oleic acid (OA) increased cholesterol (C) synthesis by the perfused liver as well as the activity of HMG-CoA reductase (HMGR) measured at the end of 4 hours. Other workers reported reduction in cholesterogenesis in experiments of shorter duration. To determine whether this effect of OA is biphasic, livers from fed male rats were perfused in vitro with a medium containing OA bound to BSA, glucose, and bovine erythrocytes. During the first hour, incorporation of 3H from 3H2O (23 mCi) into C was lower in the presence of OA (3,295±277 dpm/g) than in its absence (4,969±471 dpm/g), while over the 4 hour interval incorporation was elevated by OA (17,088±2,527 vs 10,278±1,288 dpm/g). Incorporation of 3H into fatty acid, was reduced by OA, the rate of C synthesis was sustained over 4 hours, while in its absence, C synthesis declined between the first and the fourth hour. The acute inhibition of C synthesis by OA does not appear to be due to increased phosphorylation of HMGR, since no difference in the activity of this enzyme (in microsomes prepared and incubated in the presence of 50 mM NaF) was apparent after 1 hour of perfusion (137±24 vs 112±34 pmol/minutes/mg for OA and control groups, respectively). The decline in the rate of C synthesis in the absence of OA was matched by a decline in HMGR activity (54±13 pmol/minute/mg after 4 hours), while in the presence of OA, HMGR activity was suresence of OA, HMGR activity was sustained (126±25 pmol/minute/mg). Total HMGR activity (measured in the absence of NaF) paralleled this change

116

Biphasic effect of oleic acid on hepatic cholesterol synthesis  

Energy Technology Data Exchange (ETDEWEB)

The authors observed previously that oleic acid (OA) increased cholesterol (C) synthesis by the perfused liver as well as the activity of HMG-CoA reductase (HMGR) measured at the end of 4 hours. Other workers reported reduction in cholesterogenesis in experiments of shorter duration. To determine whether this effect of OA is biphasic, livers from fed male rats were perfused in vitro with a medium containing OA bound to BSA, glucose, and bovine erythrocytes. During the first hour, incorporation of {sup 3}H from {sup 3}H{sub 2}O (23 mCi) into C was lower in the presence of OA (3,295{plus minus}277 dpm/g) than in its absence (4,969{plus minus}471 dpm/g), while over the 4 hour interval incorporation was elevated by OA (17,088{plus minus}2,527 vs 10,278{plus minus}1,288 dpm/g). Incorporation of {sup 3}H into fatty acid, was reduced by OA, the rate of C synthesis was sustained over 4 hours, while in its absence, C synthesis declined between the first and the fourth hour. The acute inhibition of C synthesis by OA does not appear to be due to increased phosphorylation of HMGR, since no difference in the activity of this enzyme (in microsomes prepared and incubated in the presence of 50 mM NaF) was apparent after 1 hour of perfusion (137{plus minus}24 vs 112{plus minus}34 pmol/minutes/mg for OA and control groups, respectively). The decline in the rate of C synthesis in the absence of OA was matched by a decline in HMGR activity (54{plus minus}13 pmol/minute/mg after 4 hours), while in the presence of OA, HMGR activity was sustained (126{plus minus}25 pmol/minute/mg). Total HMGR activity (measured in the absence of NaF) paralleled this change.

Fungwe, T.V.; Cagen, L.M.; Wilcox, H.G.; Heimberg, M. (Univ. of Tennessee, Memphis (United States))

1990-02-26

117

Photochemical Synthesis of the Bioconjugate Folic Acid-Gold Nanoparticles  

DEFF Research Database (Denmark)

In this paper we present a rapid and simple onepot method to obtain gold nanoparticles functionalized with folic acid using a photochemistry method. The bioconjugate folic acid-gold nanoparticle was generated in one step using a photo-reduction method, mixing hydrogen tetrachloroaurate with folic acid in different ratios and varying the illumination time of a mercury lamp (?= 255 nm). Scanning electron microscopy showed a particle size of around 40-50nm and dynamic light scattering exhibited that the zeta potential varies from -41 to -50mV with different illumination times. Storage in the dark at 4°C prolongs the stability of folic acid-gold nanoparticle suspensions to up to 26 days. Ultraviolet visible and Fourier transform infrared spectroscopy showed a surface plasmon band of around 534nm and fluorescence spectroscopy exhibited a quenching effect on gold nanoparticles in the fluorescence emission of folic acid and thus confirmed the conjugation of folic acid to the surface of gold nanoparticles. In this study we demonstrate the use of a photochemistry method to obtain folic acid-gold nanoparticles in a simple and rapid way without the use of surfactants and long reaction times. The photochemical synthesis of FA-AuNPs opens new perspectives for creating novel functional nanomaterials for biomedical applications.

León, John Jairo Castillo; Bertel, Linda

2013-01-01

118

Synthesis and characterization of magnetite nanoparticles coated with lauric acid  

Energy Technology Data Exchange (ETDEWEB)

Understanding the process of synthesis of magnetic nanoparticles is important for its implementation in in vitro and in vivo studies. In this work we report the synthesis of magnetic nanoparticles made from ferrous oxide through coprecipitation chemical process. The nanostructured material was coated with lauric acid and dispersed in aqueous medium containing surfactant that yielded a stable colloidal suspension. The characterization of magnetic nanoparticles with distinct physico-chemical configurations is fundamental for biomedical applications. Therefore magnetic nanoparticles were characterized in terms of their morphology by means of TEM and DLS, which showed a polydispersed set of spherical nanoparticles (average diameter of ca. 9 nm) as a result of the protocol. The structural properties were characterized by using X-ray diffraction (XRD). XRD pattern showed the presence of peaks corresponding to the spinel phase of magnetite (Fe{sub 3}O{sub 4}). The relaxivities r{sub 2} and r{sub 2}* values were determined from the transverse relaxation times T{sub 2} and T{sub 2}* at 3 T. Magnetic characterization was performed using SQUID and FMR, which evidenced the superparamagnetic properties of the nanoparticles. Thermal characterization using DSC showed exothermic events associated with the oxidation of magnetite to maghemite. - Highlights: • Synthesis of magnetic nanoparticles coated with lauric acid • Characterization of magnetic nanoparticles • Morphological, structural, magnetic, calorimetric and relaxometric characterization.

Mamani, J.B., E-mail: javierbm@einstein.br [Instituto do Cérebro-InCe, Hospital Israelita Albert Einstein-HIAE, 05651-901 São Paulo (Brazil); Costa-Filho, A.J. [Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto (Brazil); Cornejo, D.R. [Instituto de Física Universidade de São Paulo, USP, São Paulo (Brazil); Vieira, E.D. [Instituto de Física, Universidade Federal de Goiás, Goiânia (Brazil); Gamarra, L.F. [Instituto do Cérebro-InCe, Hospital Israelita Albert Einstein-HIAE, 05651-901 São Paulo (Brazil)

2013-07-15

119

Synthesis and characterization of magnetite nanoparticles coated with lauric acid  

International Nuclear Information System (INIS)

Understanding the process of synthesis of magnetic nanoparticles is important for its implementation in in vitro and in vivo studies. In this work we report the synthesis of magnetic nanoparticles made from ferrous oxide through coprecipitation chemical process. The nanostructured material was coated with lauric acid and dispersed in aqueous medium containing surfactant that yielded a stable colloidal suspension. The characterization of magnetic nanoparticles with distinct physico-chemical configurations is fundamental for biomedical applications. Therefore magnetic nanoparticles were characterized in terms of their morphology by means of TEM and DLS, which showed a polydispersed set of spherical nanoparticles (average diameter of ca. 9 nm) as a result of the protocol. The structural properties were characterized by using X-ray diffraction (XRD). XRD pattern showed the presence of peaks corresponding to the spinel phase of magnetite (Fe3O4). The relaxivities r2 and r2* values were determined from the transverse relaxation times T2 and T2* at 3 T. Magnetic characterization was performed using SQUID and FMR, which evidenced the superparamagnetic properties of the nanoparticles. Thermal characterization using DSC showed exothermic events associated with the oxidation of magnetite to maghemite. - Highlights: • Synthesis of magnetic nanoparticles coated with lauric acid • Characterization of magnetic nanoparticles • Morphological, structural, magnetic, calorimetric and relaxometric characterization

120

Synthesis of 3-oxaterpenoids and its application in the total synthesis of (±)-moluccanic acid methyl ester.  

Science.gov (United States)

Cascades: An InBr(3)-catalyzed intermolecular polyene cyclization initiated by a Prins reaction provides a concise approach to 3-oxaterpenoid derivatives. The reaction is compatible with various aldehydes, ketones, and polyolefin-alcohol substrates. In addition, the total synthesis of (±)-moluccanic acid methyl ester was achieved in seven steps by using such a Prins-polyene cyclization as the key step. PMID:22987395

Li, Bin; Lai, Yin-Chang; Zhao, Yujun; Wong, Yiu-Hang; Shen, Zhi-Liang; Loh, Teck-Peng

2012-10-15

121

Bioorganic Synthesis; Monosodium Glutamate and Other Amino Acids  

Science.gov (United States)

The March featured molecules are discussed in the article "The Monosodium Glutamate Story: The Commercial Production of MSG and Other Amino Acids". This paper provides a number of opportunities for introducing students to the importance of stereochemistry in bioorganic synthesis. The collection here includes all of the relevant molecules in the synthesis of ?-amino-?-aminocaprolactam (ACL). The introduction of two chiral centers in the reaction of cyclohexene with NOCl results in four diastereomers, and it is instructive to ask students to predict the relative abundance of those isomers and the dependence of that distribution on the extent to which the reaction is syn- or anti-addition, and to account for the fact that the resultant oxime, and the ACL, are obtained as racemates.

122

Energetics of Amino Acid Synthesis in Alkaline Hydrothermal Environments  

Science.gov (United States)

Alkaline hydrothermal systems have received considerable attention as candidates for the origin and evolution of life on the primitive Earth. Nevertheless, sufficient information has not yet been obtained for the thermodynamic properties of amino acids, which are necessary components for life, at high temperatures and alkaline pH. These properties were estimated using experimental high-temperature volume and heat capacity data reported in the literature for several amino acids, together with correlation algorithms and the revised Helgeson-Kirkham-Flowers (HKF) equations of state. This approach enabled determination of a complete set of the standard molal thermodynamic data and the revised HKF parameters for the 20 protein amino acids in their zwitterionic and ionization states. The obtained dataset was then used to evaluate the energetics of amino acid syntheses from simple inorganic precursors (CO2, H2, NH3 and H2S) in a simulated alkaline hydrothermal system on the Hadean Earth. Results show that mixing between CO2-rich seawater and the H2-rich hydrothermal fluid can produce energetically favorable conditions for amino acid syntheses, particularly in the lower-temperature region of such systems. Together with data related to the pH and temperature dependences of the energetics of amino acid polymerizations presented in earlier reports, these results suggest the following. Hadean alkaline hydrothermal settings, where steep pH and temperature gradients may have existed between cool, slightly acidic Hadean ocean water and hot, alkaline hydrothermal fluids at the vent-ocean interface, may be energetically the most suitable environment for the synthesis and polymerization of amino acids.

Kitadai, Norio

2015-03-01

123

Antimicrobial polyurethane thermosets based on undecylenic acid: synthesis and evaluation.  

Science.gov (United States)

In the present study, plant oil-derived surface-modifiable polyurethane thermosets are presented. Polyol synthesis is carried out taking advantage of thiol-yne photopolymerization of undecylenic acid derivatives containing methyl ester or hydroxyl moieties. The prepared methyl ester-containing polyurethanes allow surface modification treatment to enhance their hydrophilicity and impart antimicrobial activity through the following two steps: i) grafting poly(propylene glycol) monoamine (Jeffamine M-600) via aminolysis and ii) Jeffamine M-600 layer complexation with iodine. The antimicrobial activity of the iodine-containing polyurethanes is demonstrated by its capacity to inhibit the growth of Staphylococcus aureus, and Candida albicans in agar media. PMID:24799194

Lluch, Cristina; Esteve-Zarzoso, Braulio; Bordons, Albert; Lligadas, Gerard; Ronda, Juan C; Galià, Marina; Cádiz, Virginia

2014-08-01

124

Enzymatic synthesis of astaxanthin n-octanoic acid esters.  

Science.gov (United States)

We examined the enzymatic synthesis of astaxanthin n-octanoic acid esters. Carriers for the immobilized enzyme and reaction conditions such as water content, reaction temperature, and time were examined using Candida cylindracea lipase (Lipase OF). Lipase OF) immobilized by a hydrophobic anion exchange resin (10% w/w content of lipase) gave the best yield in the esterification reaction of astaxanthin. Two milligrams of astaxanthin per 750 microL tri-n-octanoin (ca. 0.3%) was optimum because of the low solubility of tri-n-octanoin. The esters were obtained in a yield of 36.4% under the optimal reaction conditions. PMID:18536505

Nakao, Masahiro; Sumida, Motoo; Katano, Kenji; Fukami, Harukazu

2008-01-01

125

Optimization of Butylphosphate synthesis from O-Phosphoric Acid  

International Nuclear Information System (INIS)

This work was carried out in order to confirm results of previous work and to enhance the yield of TBP synthesis. This, many reactions have been realised under differents experimental condition (temperature, acid/ alcool molar ratio, pressure and the quantity of promoter agent 'POCL3'). the TBP yield variations as function the experimental parameters, has been expressed, using the 2n factorial plan mathematical model. The experimental results were compared to those given by the theoritical model, and the optimal conditions were then drawn out

126

Efficient synthesis of anacardic acid analogues and their antibacterial activities.  

Science.gov (United States)

Anacardic acid derivatives exhibit a broad range of biological activities. In this report, an efficient method for the synthesis of anacardic acid derivatives was explored, and a small set of salicylic acid variants synthesised retaining a constant hydrophobic element (a naphthyl tail). The naphthyl side chain was introduced via Wittig reaction and the aldehyde installed using directed ortho-metalation reaction of the substituted o-anisic acids. The failure of ortho-metalation using unprotected carboxylic acid group compelled us to use directed ortho-metalation in which a tertiary amide was used as a strong ortho-directing group. In the initial route, tertiary amide cleavage during final step was challenging, but cleaving the tertiary amide before Wittig reaction was beneficial. The Wittig reaction with protected carboxylic group (methyl ester) resulted in side-products whereas using sodium salt resulted in higher yields. The novel compounds were screened for antibacterial activity and cytotoxicity. Although substitution on the salicylic head group enhanced antibacterial activities they also enhanced cytotoxicity. PMID:23416004

Mamidyala, Sreeman K; Ramu, Soumya; Huang, Johnny X; Robertson, Avril A B; Cooper, Matthew A

2013-03-15

127

Synthesis of a conformationally constrained delta-amino acid building block  

OpenAIRE

Conformationally restricted amino acids are important components in peptidomimetics and drug design. Herein, we describe the synthesis of a novel, non-proteinogenic constrained delta amino acid containing a cyclobutane ring, cis-3(aminomethyl)cyclobutane carboxylic acid (ACCA). The synthesis of the target amino acid was achieved in seven steps, with the key reaction being a base induced intramolecular nucleophilic substitution. A small library of dipeptides was prepared through the coupling o...

O Reilly, Elaine; Pes, Lara; Ortin, Yannick; Mueller-bunz, Helge; Paradisi, Francesca

2013-01-01

128

Synthesis and characterization of acidic mesoporous borosilicate thin films.  

Science.gov (United States)

Work on the synthesis and characterization of acidic wormhole-like ordered mesoporous borosilicate thin films (MBSTFs) on silicon wafers is described in this paper. The MBSTFs coated by the dip-coating method were prepared through an evaporation-induced self-assembly (EISA) process using nonionic block copolymers as structure-directing agents. Fourier transform infrared (FT-IR) spectroscopy confirmed the formation of borosiloxane bonds (Si-O-B). High-resolution transmission electron microscopy (HRTEM) and N2 sorption evidenced a wormhole-like mesoporous structure in the MBSTFs obtained. Scanning electron microscopy (SEM) images of the cross sections and surfaces of the samples showed that MBSTFs on silicon wafers were continuous, homogeneous and did not crack. The acidic properties of the MBSTFs were characterized by FT-IR spectra of chemisorbed pyridine. The MBSTFs thus prepared may find their future applications in many fields including chemical sensors, catalysis, optical coating, molecule separation, etc. PMID:19441565

Xiu, Tongping; Liu, Qian; Wang, Jiacheng

2009-02-01

129

Lewis Acidic Ionic Liquids As New Addition Catalyst For Oleic Acid To Monoestolide Synthesis  

Directory of Open Access Journals (Sweden)

Full Text Available Estolide compound has a large potential in many industrial applications such as biodegradable lubricants and in cosmetic formulation. In this study, monoestolide can be prepared by addition reaction of oleic acid under vacuum-reflux and solvent free condition for 10 hours at 85 °C in the presence of solid zinc chloride anhydrous (ZnCl2, choline chloride (ChCl and ionic liquids (IL ChCl-ZnCl2, ChCl-FeCl3, ChCl-SnCl2, ChCl-CuCl2 as homogenous acid catalysts. These reactions were compared with common homogenous catalyst namely sulfuric acid (H2SO4. The FTIR analysis show that addition reaction using the above catalysts showed the presence of three new peaks at 1732 cm-1 for C=O ester, 967.0 cm-1 for trans-CH=CH and 1176 cm-1 for C-O-C which confirmed the existence of monoestolide. The LC-MS results showed peak for the present of new monoestolides at retention time (tR 12.3 min corresponding to m/z 563.48. Among the IL, ChCl-ZnCl2 surprisingly exhibited higher activity which is 98 % acid oleic conversion and 80 % selective for the synthesis of monoestolides. As a result, this IL gave two potential functions as a solvent as well as a green catalyst for monoestolide synthesis from oleic acid.

Nadia Farhana Adnan

2011-09-01

130

Docosahexaenoic acid synthesis in human skin fibroblasts involves peroxisomal retroconversion of tetracosahexaenoic acid.  

Science.gov (United States)

The purpose of this study was to determine whether the formation of docosahexaenoic acid in human cells occurs through a pathway that involves 24-carbon n-3 fatty acid intermediates and retroconversion. Normal human skin fibroblasts synthesized radiolabeled docosahexaenoic acid from [1-(14)C]18:3n-3, [3-(14)C]22:5n-3, [3-(14)C]24:5n-3, and [3-(14)C]24:6n-3. The amount of docosahexaenoate formed was reduced in fibroblasts defective in peroxisomal biogenesis, by 90-100% in Zellweger's syndrome and by 50-75% in infantile Refsum's disease. Fatty acid elongation and desaturation were intact in these mutant cells. No decrease in radiolabeled docosahexaenoic acid production occurred in mutant fibroblasts defective in peroxisomal alpha-oxidation or mitochondrial beta-oxidation, or in normal fibroblasts treated with methyl palmoxirate to inhibit mitochondrial beta-oxidation. Therefore, the retroconversion step in docosahexaenoic acid formation occurs through peroxisomal beta-oxidation in normal human cells. These results demonstrate that the pathway for docosahexaenoic acid synthesis in human cells involves 24-carbon intermediates. The limited ability to synthesize docosahexaenoic acid may underlie some of the pathology that occurs in genetic diseases involving peroxisomal beta-oxidation. PMID:8656081

Moore, S A; Hurt, E; Yoder, E; Sprecher, H; Spector, A A

1995-11-01

131

Cyclic diguanylic acid and cellulose synthesis in Agrobacterium tumefaciens  

International Nuclear Information System (INIS)

The occurrence of the novel regulatory nucleotide bis(3',5')-cyclic diguanylic acid (c-di-GMP) and its relation to cellulose biogenesis in the plant pathogen Agrobacterium tumefaciens was studied. c-di-GMP was detected in acid extracts of 32P-labeled cells grown in various media, and an enzyme responsible for its formation from GTP was found to be present in cell-free preparations. Cellulose synthesis in vivo was quantitatively assessed with [14C]glucose as a tracer. The organism produced cellulose during growth in the absence of plant cells, and this capacity was retained in resting cells. Synthesis of a cellulosic product from UDP-glucose in vitro with membrane preparations was markedly stimulated by c-di-GMP and its precursor GTP and was further enhanced by Ca2+. The calcium effect was attributed to inhibition of a c-di-GMP-degrading enzyme shown to be present in the cellulose synthase-containing membranes

132

Synthesis and scavenging role of furan fatty acids.  

Science.gov (United States)

Fatty acids play important functional and protective roles in living systems. This paper reports on the synthesis of a previously unidentified 19 carbon furan-containing fatty acid, 10,13-epoxy-11-methyl-octadecadienoate (9-(3-methyl-5-pentylfuran-2-yl)nonanoic acid) (19Fu-FA), in phospholipids from Rhodobacter sphaeroides. We show that 19Fu-FA accumulation is increased in cells containing mutations that increase the transcriptional response of this bacterium to singlet oxygen ((1)O2), a reactive oxygen species generated by energy transfer from one or more light-excited donors to molecular oxygen. We identify a previously undescribed class of S-adenosylmethionine-dependent methylases that convert a phospholipid 18 carbon cis unsaturated fatty acyl chain to a 19 carbon methylated trans unsaturated fatty acyl chain (19M-UFA). We also identify genes required for the O2-dependent conversion of this 19M-UFA to 19Fu-FA. Finally, we show that the presence of (1)O2 leads to turnover of 19Fu-Fa in vivo. We propose that furan-containing fatty acids like 19Fu-FA can act as a membrane-bound scavenger of (1)O2, which is naturally produced by integral membrane enzymes of the R. sphaeroides photosynthetic apparatus. PMID:25092314

Lemke, Rachelle A S; Peterson, Amelia C; Ziegelhoffer, Eva C; Westphall, Michael S; Tjellström, Henrik; Coon, Joshua J; Donohue, Timothy J

2014-08-19

133

Regulation of bile acid synthesis in rat hepatocyte monolayer cultures  

International Nuclear Information System (INIS)

Primary hepatocyte monolayer cultures (PHC) were prepared and incubated in serum free media. Cells from a cholestyramine fed rat converted exogenous [14C]-cholesterol into [14C]-bile acids at a 3-fold greater rate than rats fed a normal diet. PHC synthesize bile acids (BA) at a rate of approximately 0.06 ?g/mg protein/h. The major bile acid composition, as determined by GLC, was ?-muricholic acid (BMC) and cholic acid (CA) in a 3:1 ratio, respectively. PHC rapidly converted free BA and BA intermediates into taurine conjugated trihydroxy-BA up to 87h after plating. 3-Hydroxy-3-methylglutaryl-coenzyme A-reductase activity assayed in microsomes prepared from PHC, decreased during the initial 48h, then remained constant. Cholesterol 7?-hydroxylase activity decreased during the initial 48h, then increased during the next 48h. This occurred while whole cells produced BA at a linear rate. The effect of individual BA on bile acid synthesis (BAS) was also studied. Relative rates of BAS were measured as the conversion of [14C]-cholesterol into [14C]-BA. BA combinations were tested in order to simulate the composition of the enterohepatic circulation. The addition of TCA (525 ?M) plus TCDCA (80?M), in concentrations which greatly exceed the concentration of BA (60?M) in rate portal blood, failed to inhibit BAS. BA plus phospholipid and/or cholesterol also did not inhibit BAS. Surprisingly, crude rat bile with a final concentratioe rat bile with a final concentration comparable to those in the synthetic mix inhibited [14C]-cholesterol conversion into [14C]-BA

134

Synthesis under Microwave Irradiation, Characterization and Application of Alkyliminodimethylenediphosphonic Acids in Solvent Extraction of Uranium (VI)  

OpenAIRE

The synthesis under microwave irradiation, characterization and application of new alkyliminodimethylenediphosphonic acids in solvent extraction of uranium (VI) have been investigated. The alkyliminodimethylenediphosphonic acids synthesized were: hexadecyliminodimethylenediphosphonic acid (HIDMP, H4L1) and decyliminodimethylenediphosphonic acid (DIDMP, H4L2). After purification, these products were cha...

Bouhoun Ali, M.; Badjah Hadj Ahmed, A. Y.; Attou, M.; Elias, A.; Didi, M. A.

2011-01-01

135

ETBE synthesis over silicotungstic acid and tungstophosphoric acid catalysts calcined at different temperatures  

Energy Technology Data Exchange (ETDEWEB)

Vapor phase ethyl tertiary butyl ether synthesis was investigated using heat treated heteropoly acid catalysts, namely silicotungtsic acid (STA) and tungstophosphoric acid-Keggin (TPA-K) and these results were compared with the results obtained with untreated catalysts. ETBE synthesis experiments showed that heat treatment of TPA-K at temperatures over 473 K had caused significant decrease of its catalytic activity. Activity of STA was more stable and deactivation of this catalyst was observed by heat treatment at 673 K and above. Heat treatment at high temperatures caused loss of constitutional water of STA and TPA-K, causing loss of protons, consequently the loss of acidity of the catalysts, resulting deactivation. FT-IR, TGA-DTA and DRIFTS analyses on pyridine-adsorbed catalysts supported the conclusions related to structural changes of STA and TPA-K with heat treatment. Highest ETBE yields were obtained at around 368 K, while at temperatures over 423 K formation of DEE and ethylene were observed due to dehydration of ethanol. (author)

Degirmenci, Levent; Oktar, Nuray; Dogu, Gulsen [Department of Chemical Engineering, Gazi University, 06570 Maltepe, Ankara (Turkey)

2010-07-15

136

Synthesis of decapeptide of L-aspartic acid and benzyl-L-aspartic acid by solid phase peptide synthesis.  

Science.gov (United States)

Polyene macrolide amphotericin B (AmB) is the drug of choice for the treatment of disseminated fungal infections. However, because of its pronounced side effects, the drug has limited applicability. There are few interesting reports, which state that co-administration of the drug with homo-peptide of polyaspartic acid reduces the side effects of the drug. In our present study, an approach has been made to systematically synthesize low molecular weight heteropeptides consisting of L-aspartic acid and its derivative. It was hypothesized that such heteropeptides will reduce the toxic side effects of the drug by facile hydrophobic binding between the polymer and the drug. We have employed the strategy of solid phase peptide synthesis (SPPS) to synthesize low molecular weight hetero-peptides by using L-aspartic acid and benzyl-L-aspartic acid to induce the hydrophobic binding between the peptide and the drug. In future, the proposed methodology can be employed to tailor other polypeptides substituted with benzyl groups to reduce the nephrotoxicity of AmB. PMID:16114487

Yoo, Bong K; Miah, M A Jalil; Lee, Eung-Seok; Han, Kun

2005-07-01

137

Expression of fatty acid synthesis genes and fatty acid accumulation in haematococcus pluvialis under different stressors  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Biofuel has been the focus of intensive global research over the past few years. The development of 4th generation biofuel production (algae-to-biofuels based on metabolic engineering of algae is still in its infancy, one of the main barriers is our lacking of understanding of microalgal growth, metabolism and biofuel production. Although fatty acid (FA biosynthesis pathway genes have been all cloned and biosynthesis pathway was built up in some higher plants, the molecular mechanism for its regulation in microalgae is far away from elucidation. Results We cloned main key genes for FA biosynthesis in Haematococcus pluvialis, a green microalga as a potential biodiesel feedstock, and investigated the correlations between their expression alternation and FA composition and content detected by GC-MS under different stress treatments, such as nitrogen depletion, salinity, high or low temperature. Our results showed that high temperature, high salinity, and nitrogen depletion treatments played significant roles in promoting microalgal FA synthesis, while FA qualities were not changed much. Correlation analysis showed that acyl carrier protein (ACP, 3-ketoacyl-ACP-synthase (KAS, and acyl-ACP thioesterase (FATA gene expression had significant correlations with monounsaturated FA (MUFA synthesis and polyunsaturated FA (PUFA synthesis. Conclusions We proposed that ACP, KAS, and FATA in H. pluvialis may play an important role in FA synthesis and may be rate limiting genes, which probably could be modified for the further study of metabolic engineering to improve microalgal biofuel quality and production.

Lei Anping

2012-03-01

138

Malonic ester and acetoacetic ester synthesis of 2-[11,14C]methyl-fatty acids  

International Nuclear Information System (INIS)

Suitable conditions were sought for the synthesis of various 2-[11,14C]methyl-fatty acids by malonic ester synthesis and acetoacetic ester synthesis, both involving radio-methylation with [11,14C]CH3I. The malonic ester synthesis gave 2-[11C]methyl-fatty acids with over 60% decay-corrected yields in about 40 min and the [14C]products with somewhat higher yields at a longer time. In the acetoacetic ester synthesis, several 2-[14C]methyl-fatty acids were synthesized in 50-70% yields by the hydrolysis of the radio-methylated acetoacetates with a concentrated potassium hydroxide solution, together with by-product ketones. This hydrolysis was completed in 5 min at 70oC, whereas rather drastic conditions or a longer time were needed for the thermal decarboxylation in the malonic ester synthesis. (author)

139

21 CFR 870.3470 - Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or...  

Science.gov (United States)

...Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or polytetrafluoroethylene...Intracardiac patch or pledget made of polypropylene, polyethylene terephthalate, or polytetrafluoroethylene...intracardiac patch or pledget made of polypropylene, polyethylene terephthalate,...

2010-04-01

140

Inhibition of cell-free protein synthesis by analogues of aurintricarboxylic acid.  

Science.gov (United States)

Aurintricarboxylic acid is a potent inhibitor of cell-free protein synthesis by the post-mitochondrial supernatant of chick brain and the translation of mRNA by wheat germ lysate. Comparison of commercially available and chemically synthesized analogues of aurintricarboxylic acid indicates that the unique aurin triphenyl methane ring system and the carboxylic acid groups are both necessary for inhibition of cell-free protein synthesis in both systems. PMID:750075

Kreamer, B L; Anderson, J; Liu, D S; Sparks, M B; Richardson, A

1978-12-01

141

Electron beam induced modification of poly(ethylene terephthalate) films  

International Nuclear Information System (INIS)

Electron beam processing of poly(ethylene terephthalate) (PET) films is found to promote significant changes in the melting heat, intrinsic viscosity and polymer film-liquid (water, isooctane and toluene) boundary surface tension. These properties are featured with several maximums depending on the absorbed dose and correlating with the modification of PET surface functionality. Studies using adsorption of acid-base indicators and IR-spectroscopy revealed that the increase of PET surface hydrophilicity is determined by the oxidation of methylene and methyne groups. Electron beam treatment of PET films on the surface of N-vinylpyrrolidone aqueous solution provided graft copolymerization with this comonomer at optimum process parameters (energy 700 keV, current 1 mA, absorbed dose 50 kGy)

142

Electron beam induced modification of poly(ethylene terephthalate) films  

Energy Technology Data Exchange (ETDEWEB)

Electron beam processing of poly(ethylene terephthalate) (PET) films is found to promote significant changes in the melting heat, intrinsic viscosity and polymer film-liquid (water, isooctane and toluene) boundary surface tension. These properties are featured with several maximums depending on the absorbed dose and correlating with the modification of PET surface functionality. Studies using adsorption of acid-base indicators and IR-spectroscopy revealed that the increase of PET surface hydrophilicity is determined by the oxidation of methylene and methyne groups. Electron beam treatment of PET films on the surface of N-vinylpyrrolidone aqueous solution provided graft copolymerization with this comonomer at optimum process parameters (energy 700 keV, current 1 mA, absorbed dose 50 kGy)

Vasiljeva, I.V. [Technology Center RADIANT, 10, Kurchatova Str., 194223 St. Petersburg (Russian Federation)]. E-mail: radiant@skylink.spb.ru; Mjakin, S.V. [Technology Center RADIANT, 10, Kurchatova Str., 194223 St. Petersburg (Russian Federation); Makarov, A.V. [St.-Petersburg State University of Cinema and Television, 13, ul. Pravdy, 191126 St. Petersburg (Russian Federation); Krasovsky, A.N. [St.-Petersburg State University of Cinema and Television, 13, ul. Pravdy, 191126 St. Petersburg (Russian Federation); Varlamov, A.V. [St.-Petersburg State University of Cinema and Television, 13, ul. Pravdy, 191126 St. Petersburg (Russian Federation)

2006-10-15

143

Immobilization of silver nanoparticles on polyethylene terephthalate  

OpenAIRE

Two different procedures of grafting with silver nanoparticles (AgNP) of polyethylene terephthalate (PET), activated by plasma treatment, are studied. In the first procedure, the PET foil was grafted with biphenyl-4,4?-dithiol and subsequently with silver nanoparticles. In the second one, the PET foil was grafted with silver nanoparticles previously coated with the same dithiol. X-ray photoelectron spectroscopy and electrokinetic analysis were used for characterization of the polymer surfac...

Reznickova, Alena; Novotna, Zdenka; Kolska, Zdenka; Svorcik, Vaclav

2014-01-01

144

Fatty Acid Biosynthesis IX. : Fatty Acid Synthesis from Enzymically and Chemically Acetylated Rabbit Mammary Gland Fatty Acid Synthetase.  

DEFF Research Database (Denmark)

# 1. I. [I-14C]Acetate was covalently bound to rabbit mammary gland fatty acid synthetase by enzymic transacylation from [I-14C]acetyl-CoA. Per mole of enzyme 2 moles of acetate were bound to thiol groups and up to I mole of acetate was bound to non-thiol groups. # 2. 2. The acetyl-fatty acid synthetase complex was isolated free from acetyl-CoA. It was rapidly hydrolysed at 30°C, but hydrolysis was greatly diminished at o°C and triacetic lactone synthesis occurred. In the presence of malonyl-CoA and NADPH, all the acetate bound to fatty acid synthetase was incorporated into long-chain fatty acids. Hydrolysis of bound acetate and incorporation of bound acetate into fatty acids were inhibited to the same extent by guanidine hydrochloride. # 3. 3. Acetate was also covalently bound to fatty acid synthetase by chemical acetylation with [I-14C]acetic anhydride in the absence of CoASH. A total of 60 moles of acetate were bound per mole of fatty acid synthetase, with 20–25 moles being bound to thiol groups per mole of enzyme. Acylation did not inhibit enzyme activity. The majority of the bound acetate was stable to hydrolysis at o °C. Out of the 60 moles of acetate bound per mole of acetylated enzyme, up to 20 moles were incorporated into fatty acids in the presence of malonyl-CoA and NADPH. # 4. 4. Due to the rapid hydrolysis of acetyl-fatty acid synthetase prepared from both acetyl-CoA and acetic anhydride, direct carboxylation of acetyl-fatty acid synthetase to form malonyl-fatty acid synthetase could not be demonstrated by CO2 fixation under the experimental conditions used. With acetic anhydride as acetyl donor, there was a low rate of incorporation of acetate into fatty acids in the presence of NADPH but absence of added malonyl-CoA. This could be due to direct carboxylation of the acetate bound to fatty acid synthetase or, if any CoA were associated with the fatty acid synthetase, to carboxylation of acetyl-CoA formed by chemical acetylation of this CoA.

Carey, E. M.; Hansen, Heinz Johs. Max

1972-01-01

145

Synthesis and testing of partially lipophilic polyaminocarboxylic acids  

International Nuclear Information System (INIS)

Polyaminocarboxylic acids derived from diethylenetriamine and triethylenetetramine containing a lipophilic group have been synthesized. Compounds derived from triethylenetetramine were more effective in removing Pu in vitro from liver constituents labeled in vivo than those derived from diethylenetriamine. Alkylated acids showed a greater efficacy than their nonsubstituted counterparts. The greater efficacy was confirmed in a pilot experiment in rats with aged burdens of 241Am. The relative effectiveness of a number of structurally related chelons as well as combinations of chelating agents for the removal of 239Pu and 241Am from high molecular weight liver proteins has been reported earlier. The efficacy of a chelating agent for the decorporation of potentially harmful metal ions is dependent on three factors: the affinity of the chelon for the respective metal ion, the ability of the chelon to reach the site of metal deposition in vivo and the toxicity of the agent itself. Present experiments are directed towards the synthesis and testing of agents which have balanced hydrophilic and lipophilic properties

146

Synthesis of Enantiomerically Pure Cyclopropanes from Cyclopropylboronic Acids.  

Science.gov (United States)

A general method for the stereocontrolled synthesis of cyclopropanes is described. Various, highly stable, enantiomerically pure alkenylboronic esters 13 have been conveniently synthesized by the direct hydroboration of alkynes 11 using the new chiral 1,3,2-dioxaborolane 15. The high stability was also demonstrated by the selective deprotection of a tert-butyldimethylsilyl protecting group without hydrolyzing the boronic ester. The diastereoselective cyclopropanation of the olefins was achieved by the palladium(II) acetate catalyzed decomposition of diazomethane. This process was optimized giving cyclopropylboronic esters 20/21 in high yield (89-99%) and with good to excellent diastereomeric ratios (up to 95:5). The diastereomers were separated by means of MPLC and their configurations determined by X-ray crystallography (compound 21c), by transformation to known cyclopropanols, and by correlation of NMR data. Treatment with LiAlH(4) followed by acidic hydrolysis yielded the enantiomerically pure cyclopropylboronic acid 27 for the first time and allowed the nearly quantitative recovery of the chiral auxiliary 3. Different protocols for the Suzuki coupling reaction of compound 27 were investigated. PMID:11674750

Luithle, Joachim E. A.; Pietruszka, Jörg

1999-10-29

147

The selective generation of acetic acid directly from synthesis gas  

International Nuclear Information System (INIS)

The authors conclude that each of the ruthenium, cobalt and iodide-containing catalyst components have very specific roles to play in the ''melt'' catalyzed conversion of synthesis gas to acetic acid. C1-Oxygenate formation is only observed in the presence of ruthenium carbonyls - [Ru(CO)3I3]- is here the dominant species - and there is a direct relationship between liquid yield, ?OAc-productivity and [Ru(CO)3I3]- content. Controlled quantities of iodide ensure that initially formed MeOH is rapidly converted to the more reactive methyl iodide. Subsequent cobalt-catalyzed carbonylation to acetic acid may be preparatively attractive (>80% selectivity, good yields) relative to competing syntheses, where the [Co(CO)4]- concentration is maximized that is, where the Co/Ru ratio is >1, the syngas feedstock is rich in CO, and the initial iodide/cobalt ratios are ca. unity. Formation of cobalt-iodide species appears to be a competing, inhibitory step in this catalysis

148

Synthesis of new polyphosphonic acids, uranium extracting agents in a phosphoric medium  

International Nuclear Information System (INIS)

Synthesis of organic phosphorus compounds for liquid-liquid extraction of traces of uranium in concentrated phosphoric acid is studied in view of industrial applications. Diphosphonic acids and monoesters and also triphosphonic acids and related compounds are synthetized. Extraction tests show a better efficiency than OPPA

149

Synthesis of hyaluronic acid oligosaccharides and exploration of a fluorous-assisted approach  

OpenAIRE

The synthesis of hyaluronic acid oligomers (tri- and tetrasaccharide) is described. We have followed a pre-glycosylation oxidation strategy. Glucuronic acid units were directly employed in coupling reactions with suitably protected glucosamine derivatives. In order to simplify the puri?cation of synthetic intermediates, a ?uorous-assisted strategy has been also explored. Using this approach, a hyaluronic acid trisaccharide was prepared.

Macchione, Giuseppe; Paz, Jose? L.; Nieto, Pedro M.

2014-01-01

150

Isolation, structure, and synthesis of viridic acid, a new tetrapeptide mycotoxin of Penicillium viridicatum Westling  

International Nuclear Information System (INIS)

The isolation of a new toxic metabolite, viridic acid, from Penicillium viridicatum Westling is described. The chemical and spectroscopic properties of the compound are interpreted in terms of the tetrapeptide structure (N,N-dimethyl-o-aminobenzoyl)-glycyl-(N'-methyl-L-valyl)-o-aminobenzoic acid. The structure and chirality of viridic acid were confirmed by total synthesis

151

Inhibition of fatty acid synthesis in Escherichia coli in the absence of phospholipid synthesis and release of inhibition by thioesterase action.  

OpenAIRE

The effects of inhibition of Escherichia coli phospholipid synthesis on the accumulation of intermediates of the fatty acid synthetic pathway have been previously investigated with conflicting results. We report construction of an E. coli strain that allows valid [14C]acetate labeling of fatty acids under these conditions. In this strain, acetate is a specific precursor of fatty acid synthesis and the intracellular acetate pools are not altered by blockage of phospholipid synthesis. By use of...

Jiang, P.; Cronan, J. E.

1994-01-01

152

Effect of fatty acids on the synthesis and secretion of apolipoprotein B by rat hepatocytes  

International Nuclear Information System (INIS)

The modulation of apolipoprotein B synthesis and secretion by fatty acids in rat hepatocytes was studied. Maximum apolipoprotein B production was obtained in the case of oleic acid followed by linoleic, stearic and palmitic/linolenic acid when compared to control which was not supplemented with any fatty acids. Oleic acid was found to exert a concentration dependent increase in the secretion of [3H] apolipoprotein B into the medium while that associated with the cell layer was not affected. Pulse chase experiments in the presence of oleic acid showed that it caused an increase in the secretion of apolipoprotein B into the medium. 14C-acetate incorporation into cholesterol and cholesteryl ester associated with the cell layer and secreted very low density lipoproteins also showed an increase in the presence of oleic acid indicating an increase in cholesterogenesis. The effect of oleic acid on [3H] apolipoprotein B and very low density lipoprotein secretion appeared to be mediated through cholesterol as (i)ketoconazole, an inhibitor of cholesterol synthesis caused significant reduction in the stimulatory effect of oleic acid on apolipoprotein secretion and (ii) mevinolin, another inhibitor of cholesterol synthesis also reversed the stimulatory effect of oleic acid on apolipoprotein B secretion. These results indicated that oleic acid may influence apolipoprotein B synthesis and secretion in hepatocytes probably by affecting cholesterol/chcytes probably by affecting cholesterol/cholesteryl ester formation which may be a critical component in the secretion of apolipoprotein B as lipoproteins. (author). 21 refs., 4 figs., 2 tabs

153

Silicotungstic Acid Modified Bentonite: An Efficient Catalyst for Synthesis of Acetal Derivatives of Aldehydes and Ketones  

OpenAIRE

Acetals and ketals are among the important materials of organic synthesis and as protecting agent of carbonyl functionality. A milder, efficient and green synthesis of acetals and ketals has been developed using Silicotungstic acid modified Bentonite (STA-Ben) as a catalyst. STA-Ben has been synthesized and characterized by various analytical techniques. It has been found to be an efficient and reusable catalyst for the synthesis of acetyl derivatives in excellent yield...

Reshu Chaudhary; Monika Datta

2013-01-01

154

Synthesis of acid-functionalized composite via surface deposition of acid-containing amorphous carbon  

Science.gov (United States)

A synthetic procedure, including two steps: a hydrothermal treatment using H2SO4 solution and a thermal treatment with concentrated H2SO4 in Teflon-lined stainless autoclaves was developed to synthesize acid-functionalized composite. In this process, the carbonization of glucose which contributed to the formation of carbon species with acid functional groups occurred on the silica surface. The resultant composite, investigated by powder XRD, low temperature N2 sorption and TEM, possessed well-defined mesostructure. And it was determined by XPS that amorphous carbon was deposited at the silica surface of SBA-15. The presence of multi-functional groups in the composite was confirmed by FT-IR results. Furthermore, carboxylic and sulfonic groups could be incorporated into the composite material via the covalent bond. The composite was employed as the catalyst for the acetalization of carbonyl compounds. It was suggested that acid sites were well dispersed, which was responsible for the good performance in the catalytic test. According to these facts, a synthesis route for mesostructured composite with acid functional groups has been proposed.

Du, Bin; Zhang, Xuan; Lou, Lan-Lan; Dong, Yanling; Liu, Gaixia; Liu, Shuangxi

2012-07-01

155

Synthesis of L-ascorbic acid in the phloem  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Although plants are the main source of vitamin C in the human diet, we still have a limited understanding of how plants synthesise L-ascorbic acid (AsA and what regulates its concentration in different plant tissues. In particular, the enormous variability in the vitamin C content of storage organs from different plants remains unexplained. Possible sources of AsA in plant storage organs include in situ synthesis and long-distance transport of AsA synthesised in other tissues via the phloem. In this paper we examine a third possibility, that of synthesis within the phloem. Results We provide evidence for the presence of AsA in the phloem sap of a wide range of crop species using aphid stylectomy and histochemical approaches. The activity of almost all the enzymes of the primary AsA biosynthetic pathway were detected in phloem-rich vascular exudates from Cucurbita pepo fruits and AsA biosynthesis was demonstrated in isolated phloem strands from Apium graveolens petioles incubated with a range of precursors (D-glucose, D-mannose, L-galactose and L-galactono-1,4-lactone. Phloem uptake of D-[U-14C]mannose and L-[1-14C]galactose (intermediates of the AsA biosynthetic pathway as well as L-[1-14C]AsA and L-[1-14C]DHA, was observed in Nicotiana benthamiana leaf discs. Conclusions We present the novel finding that active AsA biosynthesis occurs in the phloem. This process must now be considered in the context of mechanisms implicated in whole plant AsA distribution. This work should provoke studies aimed at elucidation of the in vivo substrates for phloem AsA biosynthesis and its contribution to AsA accumulation in plant storage organs.

Haupt Sophie

2003-11-01

156

Retinoic acid synthesis and hindbrain patterning in the mouse embryo.  

Science.gov (United States)

Targeted disruption of the murine retinaldehyde dehydrogenase 2 (Raldh2) gene precludes embryonic retinoic acid (RA) synthesis, leading to midgestational lethality (Niederreither, K., Subbarayan, V., Dolle, P. and Chambon, P. (1999). Nature Genet. 21, 444-448). We describe here the effects of this RA deficiency on the development of the hindbrain and associated neural crest. Morphological segmentation is impaired throughout the hindbrain of Raldh2-/- embryos, but its caudal portion becomes preferentially reduced in size during development. Specification of the midbrain region and of the rostralmost rhombomeres is apparently normal in the absence of RA synthesis. In contrast, marked alterations are seen throughout the caudal hindbrain of mutant embryos. Instead of being expressed in two alternate rhombomeres (r3 and r5), Krox20 is expressed in a single broad domain, correlating with an abnormal expansion of the r2-r3 marker Meis2. Instead of forming a defined r4, Hoxb1- and Wnt8A-expressing cells are scattered throughout the caudal hindbrain, whereas r5/r8 markers such as kreisler or group 3/4 Hox genes are undetectable or markedly downregulated. Lack of alternate Eph receptor gene expression could explain the failure to establish rhombomere boundaries. Increased apoptosis and altered migratory pathways of the posterior rhombencephalic neural crest cells are associated with impaired branchial arch morphogenesis in mutant embryos. We conclude that RA produced by the embryo is required to generate posterior cell fates in the developing mouse hindbrain, its absence leading to an abnormal r3 (and, to a lesser extent, r4) identity of the caudal hindbrain cells. PMID:10654602

Niederreither, K; Vermot, J; Schuhbaur, B; Chambon, P; Dollé, P

2000-01-01

157

A Facile and Efficient Synthesis of N-aryl Imides Using Trifluoroacetic Acid  

Directory of Open Access Journals (Sweden)

Full Text Available An efficient protocol has been demonstrated for the synthesis of pthalimides, maleimides and succinimides in excellent yield using trifluoroacetic acid as the reaction medium and promoter.

Sunita B. Shinde

2011-04-01

158

The Synthesis of an Amino Acid Derivative and Spectroscopic Monitoring of Dipeptide Formation.  

Science.gov (United States)

Described are experiments to give students experience in the synthesis of peptides from amino acids and to use visible spectroscopy to measure a rate of reaction. The activities were designed for undergraduate courses. (RH)

Simmonds, Richard J.

1987-01-01

159

Synthesis of unsymmetrical imidazolium salts by direct quaternization of N-substituted imidazoles using arylboronic acids.  

Science.gov (United States)

Imidazolium salts were conveniently prepared by direct aryl quaternization using arylboronic acids. This process features the tolerance of a broad range of functional groups and excellent chemoselectivity, and is especially effective for the synthesis of unsymmetrical imidazolium salts. PMID:24599288

Li, Shiqing; Yang, Fan; Lv, Taiyong; Lan, Jingbo; Gao, Ge; You, Jingsong

2014-04-18

160

Decreased nucleic acid synthesis in low-dose-irradiated lymphocytes--effect of TCGF addition  

International Nuclear Information System (INIS)

Flow cytometry was used to evaluate nucleic acid synthesis in irradiated mixed lymphocyte cultures (MLC) compared to nonirradiated control cultures. Two staining methods were used (propidium iodide and acridine orange). We showed that RNA and DNA synthesis are retarded in MLC receiving 0.2 Gy. This effect was reversed by lymphocyte growth factor

161

Delftia tsuruhatensis sp. nov., a terephthalate-assimilating bacterium isolated from activated sludge.  

Science.gov (United States)

A terephthalate-assimilating bacterium was isolated from activated sludge collected from a domestic wastewater treatment plant in Japan by enrichment with terephthalate as sole carbon source. The isolate, designated strain T7(T), was a Gram-negative, short rod-shaped micro-organism. A phylogenetic study based on 16S rRNA gene sequences indicated that strain T7(T) should be placed in the genus DELFTIA: A DNA-DNA hybridization value of 69 % was determined between strain T7(T) and Delftia acidovorans ATCC 15668(T). Major cellular fatty acids of strain T7(T) were C(16 : 0), C(16 : 1) and C(18 : 1). Substantial amounts of cyclopropanoic acid (C(17 : 0)), 3-OH C(10 : 0), C(12 : 0), C(15 : 0) and C(14 : 0) were also detected. The total DNA G+C content of strain T7(T) was 66.2 mol%. Strain T7(T) could utilize the following compounds as carbon sources: acetamide, beta-alanine, citrate, D-fructose, glycerol, isobutyrate, isophthalate, D(-)-mannitol, maleate, malonate, phenylacetate, propionate, protocatechuate, terephthalate, D-tryptophan and L-tryptophan. Comparisons of phenotypic and genotypic characteristics with other known species belonging to the genus Delftia suggest that strain T7(T) represents a novel species, for which the name Delftia tsuruhatensis sp. nov. is proposed; strain T7(T) is the type strain (=IFO 16741(T)=ATCC BAA-554(T)). PMID:13130036

Shigematsu, Toru; Yumihara, Kazuyo; Ueda, Yutaka; Numaguchi, Masaki; Morimura, Shigeru; Kida, Kenji

2003-09-01

162

Efficient Synthesis of Suitably Protected ?-Difluoroalanine and ?-Difluorothreonine from L-Ascorbic Acid  

OpenAIRE

Fluorinated amino acids are useful building blocks for the preparation of biologically active peptides and peptidomimetics with increased metabolic stability. We report here the synthesis of two fluorinated amino acids, ?-difluoroalanine and ?-difluorothreonine as analogs of Ser and Thr, respectively. These compounds were suitably protected for Fmoc-based solid phase peptide synthesis. Once incorporated into peptides, they may serve as alternative substrates or inhibitors of lantibiotic syn...

Li, Gongyong; Donk, Wilfred A.

2007-01-01

163

Highly Efficient Procedure for the Synthesis of Fructone Fragrance Using a Novel Carbon based Acid  

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Full Text Available The novel carbon based acid has been synthesized via one-step hydrothermal carbonization of furaldehyde and hydroxyethylsulfonic acid. A highly efficient procedure for the synthesis of fructone has been developed using the novel carbon based acid. The results showed that the catalyst possessed high activity for the reaction, giving a yield of over 95%. The advantages of high activity, stability, reusability and low cost for a simple synthesis procedure and wide applicability to various diols and ?-keto esters make this novel carbon based acid one of the best choices for the reaction.

Xuezheng Liang

2010-08-01

164

The synthesis and characterisation of some ortho-substituted phenoxyalkanoic acids and their derivatives  

OpenAIRE

The synthesis of 2-phenoxyalkanoic acids (ethanoic, propanoic, butanoic) was realised by the reaction of ortho-hydroxybenzamide respectively N-phenyl-o-hydroxybenzamide with a-halogenated acids in aqueous sodium hydroxide solution. 2-[o-(carbamoyl)phenoxy]-2-methyl- and 2-[o-(phenylcarbamoyl)phenoxy]-2-methyl- propanoic acids were obtained by reaction of the appropriate amide with acetone, chloroform and sodium hydroxide. Ethyl esters of 2-phenoxyalkanoic acids were obtained by the reaction o...

VALENTIN BADEA; IOANA IENASCU; CORNELIU TARABASANU; IULIANA POPESCU; ALFA XENIA LUPEA

2006-01-01

165

The involvement of amino acids in latex lipid synthesis in Euphorbia lathyris seedlings  

OpenAIRE

The breakdown of triglycerides and proteins in the endosperm of Euphorbia lathyris was assayed in a 14 day germination period. Six days after germination, the average daily production was 2.7 ?mol of amino acids. Arginine, glutamine, asparagine and glutamic acid accounted for 53% of the total amino acids. Excised cotyledons with 1 cm hypocotyls were used for amino acid uptake and their involvement in terpenoid synthesis was studied. Glutamine and aspartate were hardly involved in apolar lipi...

Groeneveld, H. W.; Elings, J.

1984-01-01

166

Synthesis and characterization of mesoporous titanium modified with tungstosilicic acid  

International Nuclear Information System (INIS)

The synthesis of titania uses urea to form pores, with sol-gel type reactions catalyzed by HCI. During the gelation process an alcoholic solution of tungstosilicic acid (TSA) is added. The amount of acid varied in order to obtain TSA contents of 0%, 10%, 20% and 30 % in weight in the material (TiTSA00, TiTSA10, TiTSA20 and TiTSA30, respectively). The urea was extracted with water and the solid thus obtained was treated at 100, 200, 300, 400, 500 y 600oC. The solids obtained were determined to be mesoporous with a pore diameter (Dp) greater than 3.0 nm. The specific area (SBET) decreases and the Dp increases when the TSA content is increased. When the calcination temperature increases SBET decreases and this reduction is less when the TSA content in the solids increases. The XRD diagrams of the samples modified with TSA only display the characteristic peaks of the anatase phase. The crystal size (DC) of the solids treated at 100oC, does not depend on the content of TSA and they are about 5.0 nm. While the crystallinity and DC increase with the increase in the temperature of calcination. According to the FT-IR spectrum the [SiW12O40]4- type is mostly present in the solids. The DRS spectrums of the samples TiTSA00T100, TiTSA10T100, TiTSA20T100 and TiTSA30T100 show continuous shift to the network of the threshtinuous shift to the network of the threshold at the beginning of the absorption band as a result of the addition of TSA. The band gap values obtained from the DRS UV-VIS spectrums are slightly less than those reported for the anatase (au)

167

Preparation, characterization and catalytic properties of MCM-48 supported tungstophosphoric acid mesoporous materials for green synthesis of benzoic acid  

Energy Technology Data Exchange (ETDEWEB)

MCM-48 and tungstophosphoric acid (HPW) were prepared and applied for the synthesis of HPW/MCM-48 mesoporous materials. The characterization results showed that HPW/MCM-48 obtained retained the typical mesopore structure of MCM-48, and the textural parameters decreased with the increase loading of HPW. The catalytic oxidation results of benzyl alcohol and benzaldehyde with 30% H{sub 2}O{sub 2} indicated that HPW/MCM-48 was an efficient catalyst for the green synthesis of benzoic acid. Furthermore, 35 wt% HPW/MCM-48 sample showed the highest activity under the reaction conditions. Highlights: • 5–45 wt% HPW/MCM-48 mesoporous catalysts were prepared and characterized. • Their catalytic activities for the green synthesis of benzoic acid were investigated. • HPW/MCM-48 was approved to be an efficient catalyst. • 5 wt% HPW/MCM-48 exhibited the highest catalytic activity.

Wu, Hai-Yan; Zhang, Xiao-Li; Chen, Xi; Chen, Ya; Zheng, Xiu-Cheng, E-mail: zhxch@zzu.edu.cn

2014-03-15

168

Preparation, characterization and catalytic properties of MCM-48 supported tungstophosphoric acid mesoporous materials for green synthesis of benzoic acid  

International Nuclear Information System (INIS)

MCM-48 and tungstophosphoric acid (HPW) were prepared and applied for the synthesis of HPW/MCM-48 mesoporous materials. The characterization results showed that HPW/MCM-48 obtained retained the typical mesopore structure of MCM-48, and the textural parameters decreased with the increase loading of HPW. The catalytic oxidation results of benzyl alcohol and benzaldehyde with 30% H2O2 indicated that HPW/MCM-48 was an efficient catalyst for the green synthesis of benzoic acid. Furthermore, 35 wt% HPW/MCM-48 sample showed the highest activity under the reaction conditions. Highlights: • 5–45 wt% HPW/MCM-48 mesoporous catalysts were prepared and characterized. • Their catalytic activities for the green synthesis of benzoic acid were investigated. • HPW/MCM-48 was approved to be an efficient catalyst. • 5 wt% HPW/MCM-48 exhibited the highest catalytic activity

169

Polyethylene terephthalate thin films; a luminescence study  

Science.gov (United States)

Polyethylene Terephthalate (PET) films doped with Rare Earths (RE3+) have been deposited on glass by spray pyrolysis technique at 240 °C, using recycled PET and (RE3+) chlorides as precursors. Cerium, terbium, dysprosium and europium were used as dopants materials, these dopants normally produce luminescent emissions at 450, 545, 573 and 612 nm respectively; the doped films also have light emissions at blue, green, yellow and red respectively. All RE3+ characteristic emissions were observed at naked eyes. Every deposited films show a high transmission in the visible range (close 80% T), films surfaces are pretty soft and homogeneous. Films thickness is around 3 ?m.

Carmona-Téllez, S.; Alarcón-Flores, G.; Meza-Rocha, A.; Zaleta-Alejandre, E.; Aguilar-Futis, M.; Murrieta S, H.; Falcony, C.

2015-04-01

170

Approaches toward high oxygen barrier poly(ethylene terephthalate) and preparation of di-isocyanate infused clay aerogel composites  

Science.gov (United States)

The first part of this dissertation discusses the synthesis and characterization of new poly(ethylene terephthalate) (PET) copolymers produced with 5-adamantylisophthalic acid monomer. Both monomer and copolymer syntheses are given in detail. Differential scanning calorimetry analyses of copolymers showed decreased melt transition temperatures with increased comonomer incorporation (0 to 5 mol-%), while copolymer glass transition temperatures increased slightly. Oxygen permeability was shown to increase with higher 5-adamantylisophthalic acid incorporation in the copolymers relative to virgin PET. The second part of this dissertation discusses PET-montmorillonite clay layered nanocomposites. Most commercially available, organically modified clays (OMCs) do not exhibit sufficient thermal stability for processing in commodity polymers such as poly(ethylene terephthalate). Surfactant degradation often leads to polymer discoloration and may be partially responsible for incomplete dispersion of the OMCs into PET. Our goal was to study the thermal stability of 4-(dimethylamino)pyridinium and 1,2-dimethylimidazolium surfactants, with a variety of long aliphatic hydrocarbon based tails on sodium exchanged montmorillonite, laponite, and fluoromica. Surfactant-sodium ion exchange resulted in increased onset of mass loss (OML) temperatures for surfactants on clays. Solvent extraction of unbound surfactant from OMC and lower percent surfactant-sodium ion exchange resulted in increased OML temperatures. Clay substrate also affects the OML temperature and mass loss profile. Preliminary experiments with these new OMCs and PET, at low incorporation via autoclave polymerization and melt-mixing, showed limited dispersion of silicate layers into the PET matrix and negligible changes to polymer thermal properties. The final part of this dissertation discusses diisocyanate infused montmorillonite aerogel composites. A process for the conversion of clay powder to organically modified clay aerogels (OMAs) is reported. The results show that stable OMAs are formed from stable clay-surfactant hydrogels. Isolated OMAs were then infused with diisocyanate monomers and cured to produce OMA composites. Rigid composites were formed with retained aerogel structure. The specific compression modulus of OMAs was improved with the infiltration and curing of diisocyanate monomer. Such aerogel structures and composites may be useful in polymer silicate layered composites, insulation applications and perhaps as supports for biologically active molecules.

Somlai, Louis Steven

171

Synthesis and characterization of Fatty acid/amino Acid self-assemblies.  

Science.gov (United States)

In this paper, we discuss the synthesis and self-assembling behavior of new copolymers derived from fatty acid/amino acid components, namely dimers of linoleic acid (DLA) and tyrosine derived diphenols containing alkyl ester pendent chains, designated as "R" (DTR). Specific pendent chains were ethyl (E) and hexyl (H). These poly(aliphatic/aromatic-ester-amide)s were further reacted with poly(ethylene glycol) (PEG) and poly(ethylene glycol methyl ether) of different molecular masses, thus resulting in ABA type (hydrophilic-hydrophobic-hydrophilic) triblock copolymers. We used Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies to evaluate the chemical structure of the final materials. The molecular masses were estimated by gel permeation chromatography (GPC) measurements. The self-organization of these new polymeric systems into micellar/nanospheric structures in aqueous environment was evaluated using ultraviolet/visible (UV-VIS) spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). The polymers were found to spontaneously self-assemble into nanoparticles with sizes in the range 196-239 nm and critical micelle concentration (CMC) of 0.125-0.250 mg/mL. The results are quite promising and these materials are capable of self-organizing into well-defined micelles/nanospheres encapsulating bioactive molecules, e.g., vitamins or antibacterial peptides for antibacterial coatings on medical devices. PMID:25347356

Gajowy, Joanna; Bolikal, Durgadas; Kohn, Joachim; Fray, Miroslawa El

2014-01-01

172

Suppression of glycosaminoglycan synthesis by articular cartilage, but not of hyaluronic acid synthesis by synovium, after exposure to radiation  

International Nuclear Information System (INIS)

We recently found that injection of 2 mCi of yttrium 90 (90Y; approximately 23,000 rads) into normal canine knees stimulated glycosaminoglycan (GAG) synthesis by femoral condylar cartilage. The present investigation was conducted to determine whether radiation affects cartilage metabolism directly. Rates of GAG synthesis and degradation in normal canine articular cartilage were studied following irradiation. Cultured synovium from the same knees was treated similarly, to determine the effects of irradiation on hyaluronic acid synthesis. Twenty-four hours after exposure to 1,000 rads, 10,000 rads, or 50,000 rads, 35S-GAG synthesis by the cartilage was 93%, 69%, and 37%, respectively, of that in control, nonirradiated cartilage. The effect was not rapidly reversible: 120 hours after exposure to 50,000 rads, GAG synthesis remained at only 28% of the control level. Autoradiography showed marked suppression of 35S uptake by chondrocytes after irradiation. Cartilage GAG degradation was also increased following irradiation: 4 hours and 8 hours after exposure to 50,000 rads, the cartilage GAG concentration was only 66% and 54%, respectively, of that at time 0, while corresponding values for control, nonirradiated cartilage were 90% and 87%. In contrast to its effects on cartilage GAG metabolism, radiation at these levels had no effect on synovial hyaluronic acid synthesis

173

Scientific Opinion on the safety evaluation of the active substances, terephthalic acid, dimethyl ester , polymer with 1,4-butanediol, cyclized, polymers with glycidyl methacrylate, hydroxyl-terminated polybutadiene, methyl methacrylate and styrene, and cobalt stearate for use in food contact materials  

Directory of Open Access Journals (Sweden)

Full Text Available

This scientific opinion of EFSA deals with the safety evaluation of the oxygen absorber (terephthalic acid, dimethyl ester, polymer with 1,4-butanediol, cyclized, polymers with glycidyl methacrylate, hydroxyl-terminated polybutadiene, methyl methacrylate and styrene copolymer (CAS No 1223402-34-3, FCM substance No 1005 and the oxidation catalyst cobalt stearate (CAS No 1002-88-6 and FCM Substance No 1004, intended to be used up to a maximum percentage of 1% in polyethylene terephtalate (PET for absorbing oxygen from the food environment. All starting substances of the oxygen absorber formulation and cobalt stearate have been evaluated and approved for use as additives in plastic food contact materials. Methyl methacrylate, glycidyl methacrylate and cobalt stearate were not detected at the detection limits of 0.6, 0.006 and 0.0005 mg/kg food simulant, respectively. Butadiene was not detected in the PET bottles at a detection limit of 0.33 mg/kg plastic. For PET formulated with the maximum 1% of the active copoymer, the migration of the low molecular weight fraction (LMWF of the copolymer was estimated to be less than 35 µg/kg food. The CEF Panel concluded that the use of the copolymer up to 1% w/w in PET for contact with all types of foods at temperature up to 95°C and the use of cobalt stearate as oxidation catalyst in PET, is not of safety concern for the consumer.

EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF

2012-10-01

174

Synthesis of the Demospongic Compounds, (6Z, 11Z-Octadecadienoic Acid and (6Z, 11Z-Eicosadienoic Acid  

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Full Text Available A stereoselective synthesis of (6Z, 11Z-octadecadienoic acid (1 and (6Z, 11Z-eicosadienoic acid (2 from easily accessible pentane-1,5-diol (3 is described. Thus, compound 3 on pyranylation and oxidation gave the aldehyde 5 which was converted to the acid 7 by Wittig reaction with a suitable phosphorane. Its depyranylation and oxidation furnished the key aldehyde 9 which upon Wittig reaction with n-heptylidene and n-nonylidene phosphoranes, respectively followed by alkaline hydrolysis afforded the title acids.

V. R. Mamdapur

1997-01-01

175

Characterization of a novel N-acetylneuraminic acid lyase favoring N-acetylneuraminic acid synthesis.  

Science.gov (United States)

N-Acetylneuraminic acid lyase (NAL, E.C. number 4.1.3.3) is a Class I aldolase that catalyzes the reversible aldol cleavage of N-acetylneuraminic acid (Neu5Ac) from pyruvate and N-acetyl-D-mannosamine (ManNAc). Due to the equilibrium favoring Neu5Ac cleavage, the enzyme catalyzes the rate-limiting step of two biocatalytic reactions producing Neu5Ac in industry. We report the biochemical characterization of a novel NAL from a "GRAS" (General recognized as safe) strain C. glutamicum ATCC 13032 (CgNal). Compared to all previously reported NALs, CgNal exhibited the lowest kcat/Km value for Neu5Ac and highest kcat/Km values for ManNAc and pyruvate, which makes CgNal favor Neu5Ac synthesis the most. The recombinant CgNal reached the highest expression level (480?mg/L culture), and the highest reported yield of Neu5Ac was achieved (194?g/L, 0.63?M). All these unique properties make CgNal a promising biocatalyst for industrial Neu5Ac biosynthesis. Additionally, although showing the best Neu5Ac synthesis activity among the NAL family, CgNal is more related to dihydrodipicolinate synthase (DHDPS) by phylogenetic analysis. The activities of CgNal towards both NAL's and DHDPS' substrates are fairly high, which indicates CgNal a bi-functional enzyme. The sequence analysis suggests that CgNal might have adopted a unique set of residues for substrates recognition. PMID:25799411

Ji, Wenyan; Sun, Wujin; Feng, Jinmei; Song, Tianshun; Zhang, Dalu; Ouyang, Pingkai; Gu, Zhen; Xie, Jingjing

2015-01-01

176

Formation of cobalt(II) piperazine supramolecular systems under different organic acid mediums: synthesis, characterization and crystal structures  

Science.gov (United States)

The reactions of CoCl 2 salt and piperazine ( L) in the presence of different organic acid mediums afford a series of cobalt(II) complexes, the solid structures (determined by X-ray diffraction techniques) of which are controlled by the nature of the specific acid. When terephthalic acid was used, a novel mononuclear molecule [Co(H L) 2Cl 3]·Cl·(H 2O) ( 1) was obtained [orthorhombic, Pnma, a=24.604(16) Å, b=9.882(7) Å, c=6.609(4) Å, Z=4], in which the Co II center takes the unusual compressed trigonal-bipyramidal coordination geometry (CoN 2Cl 3) and multiple hydrogen-bonding interactions extend this structure into a three-dimensional supramolecular network. However, with the replacement of terephthalic acid with malonic acid in the above reaction, a one-dimensional coordination polymer [Co LCl 2] n ( 2) was obtained [monoclinic, P2 1/ n, a=6.363(3) Å, b=10.244(5) Å, c=12.124(5) Å, ?=103.560(8)°, Z=4], in which the tetrahedral Co II centers (CoCl 2N 2) are linked by the bidentate-coordinated piperazine molecules to form a zigzag chain array and these coordination chains are further expanded to a three-dimensional hydrogen-bonding architecture. In addition, a mononuclear complex [Co(gly) 3]·(H 2O) ( 3) [monoclinic, P2 1/ c, a=6.261(5) Å, b=14.280(9) Å, c=12.182(8) Å, ?=101.450(14)°, Z=4] was yielded when glycine was used in the similar procedure. A three-dimensional framework is also observed through the hydrogen-bonding interactions between [Co(gly) 3] moieties, in which the guest water molecules are included. These results unequivocally indicate that the nature of the organic acid templates play the key role in formation of these complexes.

Zhao, Xiao-Jun; Du, Miao; Wang, Ying; Bu, Xian-He

2004-04-01

177

Synthesis of ?-amino acids based on chiral tricycloiminolactone derived from natural (+)-camphor.  

Science.gov (United States)

Amino acids are one of the most important classes of the building blocks of life: they are the structural subunits of proteins, peptides, and many secondary metabolites. In addition to the 20 ?-amino acids that constitute the backbone of proteins, hundreds of other natural ?-amino acids have been discovered either in free form or as components in natural products. The difference between these molecules is the substituents at the chiral carbon situated between the amino and carboxyl moieties; this carbon (and any atom along a chain attached to it) is thus an important synthetic target. Because tailor-made ?-amino acids are increasingly popular in biochemistry and organic synthesis, further refinement in synthetic methods to generate both natural (L-configuration) and unnatural (D-configuration) amino acids is a very active area of current research. In this Account, we examine the tricycloiminolactones, which are versatile glycine equivalents derived from natural camphor. We have developed the tricycloiminolactones in our laboratory and used them in the synthesis of several kinds of enantiopure ?-amino acids. As nucleophiles, enolated tricycloiminolactones were shown to successfully participate in alkylations, Aldol reactions, Michael additions, and Mannich reactions. These reactions all gave excellent stereoselectivities and high yields. Simple conversion of the products offered ?-alkyl-?-amino acids, ?,?-dialkyl-?-amino acids, ?-hydroxy-?-amino acids, ?,?-diamino acids, and ?,?-diamino acids. One particular advantage is that the same electrophile can react with two chiral templates in the same way, thus affording access to both enantiomeric amino acids. In other words, some natural (L-configuration) ?-amino acids and their unnatural (D-configuration) counterparts can be prepared very conveniently. The relation between substrate structures and product stereoconformations derived from our investigations serves as a convenient guide in the synthesis of useful chiral amino acids. In addition, highly stereoselective 1,3-diploar cycloadditions between alkenes and chiral nitrones derived from tricycloiminolactones provide a potential method for the synthesis of ?-hydroxy-?-amino acids. We also discuss applications of our methods in the synthesis of complex natural products, including conagenin, polyoxamic acid, lactacystin, and sphingofungin F. The preparation of some clinically important drug molecules, such as thiaphenicol, florfenicol, and chloramphenicol, was greatly simplified with our methods. The tricycloiminolactones offer a number of advantages in the synthesis of both natural and unnatural ?-amino acids and provide many useful building blocks in the synthetic pursuit of complex molecules. PMID:20672798

Luo, Yong-Chun; Zhang, Huan-Huan; Wang, Yao; Xu, Peng-Fei

2010-10-19

178

A new synthesis of double labeled [7,9-13C2] folic acid  

International Nuclear Information System (INIS)

A convenient small scale chemical synthesis of double labeled folic acid with 13C at positions C-7 and C-9 is reported. [1,3-13C2] acetone was converted into folic acid in two steps, with [1, 1, 3]-trichloroacetone as the labeled intermediate. (Author)

179

4-Dimenthylaminopyridine or Acid-Catalyzed Synthesis of Esters: A Comparison  

Science.gov (United States)

A set of highly atom-economic experiments was developed to highlight the differences between acid- and base-catalyzed ester syntheses and to introduce the principles of atom economy. The hydrochloric acid-catalyzed formation of an ester was compared with the 4-dimethylaminopyradine-catalyzed ester synthesis.

van den Berg, Annemieke W. C.; Hanefeld, Ulf

2006-01-01

180

INFLUENCE OF THE SYNTHESIS PARAMETERS ON SOME TEXTURAL PROPERTIES OF ROMANIAN ACID ACTIVATED BENTONITE  

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Full Text Available This paper presents the influence of synthesis parameters (concentration of acid solution and the solid: liquid ratio on textural characteristics of bentonite activated clays: nitrogen adsorption/desorption isotherms, surface and pore size distribution. Acid activated clays present higher specific surface area than the natural bentonite used as feed stock and a better adsorption capacity.

URSU ALINA VIOLETA

2010-08-01

181

Synthesis and characterization of some N-substituted amides of salicylic acid  

OpenAIRE

The synthesis of some N-substituted aromatic amides in the salicylic acid series was achieved, by direct reaction between primary amines and salicylic acid in inert organic solvent, in the presence of PCl3. The compounds that were obtained, partially not described in literature, were characterized by chemical-physical methods.

Lupea Xenia Alfa; Padure Mirabela

2003-01-01

182

Exogenous fatty acids affect CDP-choline pathway to increase phosphatidylcholine synthesis in granular pneumocytes  

International Nuclear Information System (INIS)

Regulation of phosphatidylcholine (PC) synthesis in rat granular pneumocytes isolated by tryptic digestion of lungs and maintained in primary culture for 24 h was investigated by following effects of exogenous fatty acids on [3H-methyl]choline incorporation into PC and disaturated PC (DSPC). At 0.1 mM choline, the rate of choline incorporation into PC and DSPC was 440 +/- and 380 +/- 50 pmol/h/ug Pi (mean +/- SE, n=3-5), respectively, and was linear for up to 3 h. PC synthesis was significantly increased by 0.1 mM each of palmitic, oleic, linoleic, or linolenic acid. However, synthesis of DSPC was increased only by palmitic acid and this increase was prevented by addition of oleic acid suggesting lack of effect on the remodeling pathway. Pulse-chase experiments with choline in absence or presence of palmitic or oleic acid showed that the label declined in choline phosphate and increased in PC more rapidly in presence of either of the fatty acids, suggesting rapid conversion of choline phosphate to PC. Microsomal choline phosphate cytidyltransferase activity in cells preincubated without or with palmitic acid for 3 h was 0.81 +/- 0.07 and 1.81 +/- 0.09 nmol choline phosphate converted/min/mg protein (n=4). These results suggest that in granular pneumocytes, exogenous fatty acids modulate PC synthesis by increasing choline phosphate cytidyltransferase activity

183

Exogenous fatty acids affect CDP-choline pathway to increase phosphatidylcholine synthesis in granular pneumocytes  

Energy Technology Data Exchange (ETDEWEB)

Regulation of phosphatidylcholine (PC) synthesis in rat granular pneumocytes isolated by tryptic digestion of lungs and maintained in primary culture for 24 h was investigated by following effects of exogenous fatty acids on (/sup 3/H-methyl)choline incorporation into PC and disaturated PC (DSPC). At 0.1 mM choline, the rate of choline incorporation into PC and DSPC was 440 +/- and 380 +/- 50 pmol/h/ug Pi (mean +/- SE, n=3-5), respectively, and was linear for up to 3 h. PC synthesis was significantly increased by 0.1 mM each of palmitic, oleic, linoleic, or linolenic acid. However, synthesis of DSPC was increased only by palmitic acid and this increase was prevented by addition of oleic acid suggesting lack of effect on the remodeling pathway. Pulse-chase experiments with choline in absence or presence of palmitic or oleic acid showed that the label declined in choline phosphate and increased in PC more rapidly in presence of either of the fatty acids, suggesting rapid conversion of choline phosphate to PC. Microsomal choline phosphate cytidyltransferase activity in cells preincubated without or with palmitic acid for 3 h was 0.81 +/- 0.07 and 1.81 +/- 0.09 nmol choline phosphate converted/min/mg protein (n=4). These results suggest that in granular pneumocytes, exogenous fatty acids modulate PC synthesis by increasing choline phosphate cytidyltransferase activity.

Chander, A.; Gullo, J.; Reicherter, J.; Fisher, A.

1987-05-01

184

Stereoselective synthesis of a-hydroxy-b-amino acids: the chiral pool approach  

Directory of Open Access Journals (Sweden)

Full Text Available A method for the stereoselective homologation of a-amino acids into syn-a-hydroxy-b-amino acids is described, based on the conversion of stereoisomeric cyanohydrins into trans-oxazolines. The synthetic potential of the method is illustrated in the enantioselective formal synthesis of Bestatin.

RADOMIR N. SAICIC

2004-11-01

185

INFLUENCE OF THE SYNTHESIS PARAMETERS ON SOME TEXTURAL PROPERTIES OF ROMANIAN ACID ACTIVATED BENTONITE  

OpenAIRE

This paper presents the influence of synthesis parameters (concentration of acid solution and the solid: liquid ratio) on textural characteristics of bentonite activated clays: nitrogen adsorption/desorption isotherms, surface and pore size distribution. Acid activated clays present higher specific surface area than the natural bentonite used as feed stock and a better adsorption capacity.

URSU ALINA VIOLETA; JINESCU GHEORGHITA; NISTOR ILEANA DENISA; GEORGESCU ANA MARIA; MUNTIANU GHIMICIU GABRIELA; SILION MIHAELA

2010-01-01

186

Diesters from Oleic Acid: Synthesis, Low Temperature Properties, and Oxidation Stability  

Science.gov (United States)

Several diesters were prepared from commercially available oleic acid and common organic acids. The key step in the three step synthesis of oleochemical diesters entails a ring opening esterification of alkyl 9,10-epoxyoctadecanoates (alkyl: propyl, iso-propyl, octyl, 2-ethylhexyl) using propionic a...

187

The suppression of eicosanoid synthesis by peritoneal macrophages is influenced by the ratio of dietary docosahexaenoic acid to linoleic acid.  

Science.gov (United States)

The efficacy of docosahexaenoic acid (DHA) in suppressing eicosanoid synthesis by peritoneal macrophages in vivo was influenced by the relative amount of dietary DHA when linoleic acid (LA) was held constant. Increasing DHA from 0 to 37% of the fatty acids in diets containing 10 weight % fat (of which LA was 40%) caused an eleven-fold increase in the DHA content of macrophages. Limited retroconversion of DHA to eicosapentaenoic acid was observed. Macrophages in animals consuming DHA synthesized significantly lower amounts of leukotriene E4, prostaglandin E2 and 6-keto prostaglandin F1 alpha in vivo upon stimulation with zymosan. The maximum inhibition of eicosanoid synthesis was observed when the dietary DHA/LA ratio was 0.16 and no further inhibition occurred when the ratio was increased up to 0.81. PMID:2528666

Lokesh, B R; Black, J M; Kinsella, J E

1989-07-01

188

Radiotracer studies on the synthesis of prorennin and rennin using 14C-amino acids  

International Nuclear Information System (INIS)

In vivo incorporation of 14C-amino acids into the prorennin and rennin fractions of the abomasal tissue of the intact animal (i.e. calf) has been investigated by : (1) intravenous injection of the label and subsequent isolation of rennin and prorennin fractions from the excised abomasum and (2) feeding. of milk whey fortified with the label to a fistulated kid and subsequent processing of the abomasal juice for rennet extraction. Prorennin incorporates more radioactivity than rennin. This indicates that abomasal tissue uses blood amino acids for prorennin synthesis, but amino acids fed through dietary channels may not be used for rennin synthesis. (M.G.B.)

189

Selective inhibition of leukotriene C4 synthesis in human neutrophils by ethacrynic acid  

International Nuclear Information System (INIS)

Addition of glutathione S-transferase inhibitors, ethyacrynic acid (ET), caffeic acid (CA), and ferulic acid (FA) to human neutrophils led to inhibition of leukotriene C4 (LTC4) synthesis induced by calcium ionophore A23187. ET is the most specific of these inhibitors for it had little effect on LTB4, PGE2, and 5-HETE synthesis. The inhibition of LTC4 was irreversible and time dependent. ET also had little effect on 3H-AA release from A23187-stimulated neutrophils

190

Potency of individual bile acids to regulate bile acid synthesis and transport genes in primary human hepatocyte cultures.  

Science.gov (United States)

Bile acids (BAs) are known to regulate their own homeostasis, but the potency of individual bile acids is not known. This study examined the effects of cholic acid (CA), chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), lithocholic acid (LCA) and ursodeoxycholic acid (UDCA) on expression of BA synthesis and transport genes in human primary hepatocyte cultures. Hepatocytes were treated with the individual BAs at 10, 30, and 100?M for 48 h, and RNA was extracted for real-time PCR analysis. For the classic pathway of BA synthesis, BAs except for UDCA markedly suppressed CYP7A1 (70-95%), the rate-limiting enzyme of bile acid synthesis, but only moderately (35%) down-regulated CYP8B1 at a high concentration of 100?M. BAs had minimal effects on mRNA of two enzymes of the alternative pathway of BA synthesis, namely CYP27A1 and CYP7B1. BAs increased the two major target genes of the farnesoid X receptor (FXR), namely the small heterodimer partner (SHP) by fourfold, and markedly induced fibroblast growth factor 19 (FGF19) over 100-fold. The BA uptake transporter Na(+)-taurocholate co-transporting polypeptide was unaffected, whereas the efflux transporter bile salt export pump was increased 15-fold and OST?/? were increased 10-100-fold by BAs. The expression of the organic anion transporting polypeptide 1B3 (OATP1B3; sixfold), ATP-binding cassette (ABC) transporter G5 (ABCG5; sixfold), multidrug associated protein-2 (MRP2; twofold), and MRP3 (threefold) were also increased, albeit to lesser degrees. In general, CDCA was the most potent and effective BA in regulating these genes important for BA homeostasis, whereas DCA and CA were intermediate, LCA the least, and UDCA ineffective. PMID:25055961

Liu, Jie; Lu, Hong; Lu, Yuan-Fu; Lei, Xiaohong; Cui, Julia Yue; Ellis, Ewa; Strom, Stephen C; Klaassen, Curtis D

2014-10-01

191

Synthesis of deuterium-labelled methylphenidate, p-hydroxy-methylphenidate, ritalinic acid and p-hydroxyritalinic acid  

Energy Technology Data Exchange (ETDEWEB)

The synthesis of threo-dl-methylphenidate (Ritalin 1), threo-dl-p-hydroxy-methylphenidate (3), threo-dl-ritalinic acid (2), and threo-dl-p-hydroxyritalinic acid (4) with deuterium incorporated in the piperidine ring is described. These compounds were synthesized for use as internal standards for mass fragmentographic assays of methylphenidate and its metabolites. The synthetic scheme described resulted in less than 0.05% /sup 2/H/sub 0/ in the piperidine ring in any of the preparations.

Patrick, K.; Kilts, C.; Breese, G. (North Carolina Univ., Chapel Hill (USA). School of Medicine)

1982-04-01

192

The Prebiotic Synthesis of Ethylenediamine Monoacetic Acid, The Repeating Unit of Peptide Nucleic Acids  

Science.gov (United States)

The polymerization of ribonucleic acids or their precursors constitutes an important event in prebiotic chemistry. The various problems using ribonucleotides to make RNA suggest that there may have been a precursor. An attractive possibility are the peptide nucleic acids (PNA). PNAs are nucleotide analogs that make use of a polymer of ethylenediamine monoacetic acid (EDMA or 2-amninoethyl glycine) with the bases attached by an acetic acid. EDMA is an especially attractive alternative to the ribose phosphate or deoxyribose phosphate backbone because it contains no chiral centers and is potentially prebiotic, but there is no reported prebiotic synthesis. We have synthesized both EDMA and ethylenediamine diacetic acid (EDDA) from the prebiotic compounds ethylenediamine, formaldehyde, and hydrogen cyanide. The yields of EDMA range from 11 to 79% along with some sEDDA and uEDDA. These reactions work with concentrations of 10(exp -1)M and as low as 10(exp -4)M, and the reaction is likely to be effective at even lower concentrations. Ethylenediamine is a likely prebiotic compound, but it has not yet been demonstrated, although compounds such as ethanolamine and cysteamine have been proven to be prebiotic. Under neutral pH and heating at l00 C, EDMA is converted to the lactam, monoketopiperazine (MKP). The cyclization occurs and has an approximate ratio of MKP/EDMA = 3 at equilibrium. We have measured the solubilities of EDMA center dot H20 as 6.4 m, EDMA center dot HCl center dot H20 as 13.7 m, and EDMA center dot 2HCl center dot H20 as 3.4 m. These syntheses together with the high solubility of EDMA suggest that EDMA would concentrate in drying lagoons and might efficiently form polymers. Given the instability of ribose and the poor polymerizability of nucleotides, the prebiotic presence of EDMA and the possibility of its polymerization raises the possibility that PNAs are the progenitors of present day nucleic acids. A pre-RNA world may have existed in which PNAs or polymers with related peptide backbones were the dominant information macromolecules.

Nelson, Kevin E.; Miller, Stanley L.

1992-01-01

193

Synthesis of new indolecarboxylic acids related to the plant hormone indoleacetic acid IAA  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A síntese dos ácidos 5,6-metilenodioxi-indol-3-il-metanóico 8 e 5,6-metilenodioxi-indol-3-il-acético 13 é descrita. Piperonal foi empregado como material de partida, sendo a construção do heterociclo altamente regioespecífica e está fundamentada na reação de Hemetsberger do correspondente beta-azido [...] estireno. O composto 8 foi obtido como intermediário pivotal na preparação de 13, tendo-se conduzida a reação de Mannich para a introdução da cadeia lateral alquílica. A rota sintética empregada englobou oito etapas e conduziu a formação de 13 com rendimento total de 26%. A formação do heterociclo indólico via ciclização redutiva de o,beta-dinitroestireno é também apresentada. Abstract in english The synthesis of 5,6-methylenedioxy-indol-3-yl-methanoic acid 8 and 5,6-methylenedioxy-indol-3-yl-acetic acid 13 is described. Piperonal was employed as starting material, and the construction of the heterocyclic ring based on the Hemetsberger reaction of the corresponding beta-azidostyrene was high [...] ly regiospecific. Compound 8 was obtained as a key intermediate towards 13, and a Mannich reaction was used to introduce the required alkyl side chain. The route comprised eight steps giving 13 in 26% overall yield. The formation of the indolic ring via reductive cyclisation of o,beta-dinitrostyrene is also presented.

Flávia A. F. da, Rosa; Ricardo A., Rebelo; Maria G., Nascimento.

2003-01-01

194

Decreased hepatotoxic bile acid composition and altered synthesis in progressive human nonalcoholic fatty liver disease  

International Nuclear Information System (INIS)

Bile acids (BAs) have many physiological roles and exhibit both toxic and protective influences within the liver. Alterations in the BA profile may be the result of disease induced liver injury. Nonalcoholic fatty liver disease (NAFLD) is a prevalent form of chronic liver disease characterized by the pathophysiological progression from simple steatosis to nonalcoholic steatohepatitis (NASH). The hypothesis of this study is that the ‘classical’ (neutral) and ‘alternative’ (acidic) BA synthesis pathways are altered together with hepatic BA composition during progression of human NAFLD. This study employed the use of transcriptomic and metabolomic assays to study the hepatic toxicologic BA profile in progressive human NAFLD. Individual human liver samples diagnosed as normal, steatosis, and NASH were utilized in the assays. The transcriptomic analysis of 70 BA genes revealed an enrichment of downregulated BA metabolism and transcription factor/receptor genes in livers diagnosed as NASH. Increased mRNA expression of BAAT and CYP7B1 was observed in contrast to decreased CYP8B1 expression in NASH samples. The BA metabolomic profile of NASH livers exhibited an increase in taurine together with elevated levels of conjugated BA species, taurocholic acid (TCA) and taurodeoxycholic acid (TDCA). Conversely, cholic acid (CA) and glycodeoxycholic acid (GDCA) were decreased in NASH liver. These findings reveal a potential shift toward the alternative pathway of BA synthesis during NASH, mediated by increased mRNA and protein expression of CYP7B1. Overall, the transcriptomic changes of BA synthesis pathway enzymes together with altered hepatic BA composition signify an attempt by the liver to reduce hepatotoxicity during disease progression to NASH. - Highlights: ? Altered hepatic bile acid composition is observed in progressive NAFLD. ? Bile acid synthesis enzymes are transcriptionally altered in NASH livers. ? Increased levels of taurine and conjugated bile acids are observed in NASH. ? Hepatic bile acid synthesis shifts toward the alternative pathway in NASH

195

Decreased hepatotoxic bile acid composition and altered synthesis in progressive human nonalcoholic fatty liver disease  

Energy Technology Data Exchange (ETDEWEB)

Bile acids (BAs) have many physiological roles and exhibit both toxic and protective influences within the liver. Alterations in the BA profile may be the result of disease induced liver injury. Nonalcoholic fatty liver disease (NAFLD) is a prevalent form of chronic liver disease characterized by the pathophysiological progression from simple steatosis to nonalcoholic steatohepatitis (NASH). The hypothesis of this study is that the ‘classical’ (neutral) and ‘alternative’ (acidic) BA synthesis pathways are altered together with hepatic BA composition during progression of human NAFLD. This study employed the use of transcriptomic and metabolomic assays to study the hepatic toxicologic BA profile in progressive human NAFLD. Individual human liver samples diagnosed as normal, steatosis, and NASH were utilized in the assays. The transcriptomic analysis of 70 BA genes revealed an enrichment of downregulated BA metabolism and transcription factor/receptor genes in livers diagnosed as NASH. Increased mRNA expression of BAAT and CYP7B1 was observed in contrast to decreased CYP8B1 expression in NASH samples. The BA metabolomic profile of NASH livers exhibited an increase in taurine together with elevated levels of conjugated BA species, taurocholic acid (TCA) and taurodeoxycholic acid (TDCA). Conversely, cholic acid (CA) and glycodeoxycholic acid (GDCA) were decreased in NASH liver. These findings reveal a potential shift toward the alternative pathway of BA synthesis during NASH, mediated by increased mRNA and protein expression of CYP7B1. Overall, the transcriptomic changes of BA synthesis pathway enzymes together with altered hepatic BA composition signify an attempt by the liver to reduce hepatotoxicity during disease progression to NASH. - Highlights: ? Altered hepatic bile acid composition is observed in progressive NAFLD. ? Bile acid synthesis enzymes are transcriptionally altered in NASH livers. ? Increased levels of taurine and conjugated bile acids are observed in NASH. ? Hepatic bile acid synthesis shifts toward the alternative pathway in NASH.

Lake, April D. [University of Arizona, Department of Pharmacology and Toxicology, Tucson, AZ 85721 (United States); Novak, Petr [Biology Centre ASCR, Institute of Plant Molecular Biology, Ceske Budejovice 37001 (Czech Republic); Shipkova, Petia; Aranibar, Nelly; Robertson, Donald; Reily, Michael D. [Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, NJ 08543 (United States); Lu, Zhenqiang [The Arizona Statistical Consulting Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Lehman-McKeeman, Lois D. [Pharmaceutical Candidate Optimization, Bristol-Myers Squibb Co., Princeton, NJ 08543 (United States); Cherrington, Nathan J., E-mail: cherrington@pharmacy.arizona.edu [University of Arizona, Department of Pharmacology and Toxicology, Tucson, AZ 85721 (United States)

2013-04-15

196

Increased amino acid clearance and urea synthesis in a patient with glucagonoma.  

OpenAIRE

Fasting concentrations, clearance of exogenous infused amino acids, and lean body mass were studied in a patient with glucagonoma syndrome (fasting glucagon = 380 pmol/l, normal range 15-45 pmol). The fasting concentrations of all amino acids were reduced. The clearances of alanine, arginine, glycine, isoleucine, leucine, lysine, methionine, proline, serine, threonine, and tyrosine were increased. The urea synthesis rate during amino acid infusion was 27 mumols/kg per minute (normal range 20-...

Almdal, T. P.; Heindorff, H.; Bardram, L.; Vilstrup, H.

1990-01-01

197

Synthesis of novel (1-alkanoyloxy-4-alkanoylaminobutylidene-1,1-bisphosphonic acid derivatives  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract A novel strategy for the synthesis of (1-alkanoyloxy-4-alkanoylaminobutylidene-1,1-bisphosphonic acid derivatives (1a-d via (1-hydroxy-4-alkanoylaminobutylidene-1,1-bisphosphonic acid derivatives (2a-d, starting from alendronate has been developed with reasonable 51–77% overall yields. Intermediate products, (1-hydroxy-4-alkanoylaminobutylidene-1,1-bisphosphonic acid derivatives (2a-d, were prepared in water with reasonable to high yields (52–94%.

Vepsäläinen Jouko J

2006-02-01

198

Rosmarinic acid synthesis in transformed callus culture of Coleus blumei benth.  

Science.gov (United States)

Agrobacteria mediated Coleus blumei tumour tissues were cultured in vitro on MS medium. Sixteen diversified transformed callus cultures were maintained for several years in the absence of plant growth regulators and antibiotics without affecting the growth rate. Rosmarinic acid was detected spectrophotometrically in all tissue lines but in different quantities. The highest rosmarinic acid accumulation detected was 11% of dry tissue mass. The relation between culture growth and rosmarinic acid production was investigated in three callus lines. The lines showed different rosmarinic acid accumulation in relation to their growth rate; it was either parallel or inversely related to the tissue growth. The effects of certain medium constituents on the callus growth and rosmarinic acid accumulation were examined in four tumour cell lines. Addition of 4% or 5% sucrose stimulated rosmarinic acid synthesis and decreased callus growth. Nitrogen reduction to one half or one quarter of initial concentration did not affect rosmarinic acid synthesis and decreased callus growth in three lines, while it increased rosmarinic acid accumulation and callus growth in one line. Addition of 0.1 mg/l Phe stimulated rosmarinic acid production in two lines but had little effect on the rosmarinic acid level in others. Rosmarinic acid production was significantly improved on modified macronutrients, where the Ac2 line produced 16.5 mg of rosmarinic acid per tube (0.2 g of dry wt) after being in culture for 35 days. PMID:15813379

Bauer, Natasa; Leljak-Levanic, Dunja; Jelaska, Sibila

2004-01-01

199

Synthesis and characterization of humic acids with distinct redox capacities  

International Nuclear Information System (INIS)

Various humic acids with distinct redox capacities were synthesized, based on the oxidation of hydroquinone in alkaline solution in the presence or absence of amino acids. The synthesized humic acids show Fe(III) redox capacities which are up to 10 times higher than that of natural humic acid from Aldrich. (orig.)

200

Synthesis of 18F-FDG using improved single-pot acid hydrolysis process  

International Nuclear Information System (INIS)

In order to explore an optimum condition to increase the synthesis yield of 2-18F-2-deoxy-?-D-glucose (18F-FDG) by using improved single-pot acid hydrolysis Chemistry Process Control Unit (CPCU), various production conditions such as the reaction temperature, the time of acid hydrolysis and others were tested. The results showed that the determinant factor which affects the synthesis yield was the quantities of water present in reaction media. The total 18F-FDG synthesis time could be minimized by effective dehydration step and regulating the amount of hydrogen chloride. The synthesis yield could be increased by improving the production conditions of 18F-FDG. (authors)

201

Synthesis and Proteasome Inhibition of Glycyrrhetinic Acid Derivatives  

OpenAIRE

This study discovered that glycyrrhetinic acid inhibited the human 20S proteasome at 22.3 µM. Esterification of the C-3 hydroxyl group on glycyrrhetinic acid with various carboxylic acid reagents yielded a series of analogs with marked improved potency. Among the derivatives, glycyrrhetinic acid 3-O-isophthalate (17) was the most potent compound with IC50 of 0.22 µM, which was approximately 100-fold more potent than glycyrrhetinic acid.

Huang, Li; Yu, Donglei; Ho, Phong; Qian, Keduo; Lee, Kuo-hsiung; Chen, Chin-ho

2008-01-01

202

Calorie restriction increases fatty acid synthesis and whole body fat oxidation rates  

OpenAIRE

Calorie restriction (CR) increases longevity and retards the development of many chronic diseases, but the underlying metabolic signals are poorly understood. Increased fatty acid (FA) oxidation and reduced FA synthesis have been hypothesized to be important metabolic adaptations to CR. However, at metabolic steady state, FA oxidation must match FA intake plus synthesis; moreover, FA intake is low, not high, during CR. Therefore, it is not clear how FA dynamics are altered during CR. Accordin...

Bruss, Matthew D.; Khambatta, Cyrus F.; Ruby, Maxwell A.; Aggarwal, Ishita; Hellerstein, Marc K.

2009-01-01

203

Characterizing Elongation of Protein Synthesis and Fusidic Acid Resistance in Bacteria  

OpenAIRE

Protein synthesis is a highly complex process executed by the ribosome in coordination with mRNA, tRNAs and translational protein factors. Several antibiotics are known to inhibit bacterial protein synthesis by either targeting the ribosome or the proteins factors involved in translation. Fusidic acid (FA) is a bacteriostatic antibiotic that blocks polypeptide chain elongation by locking elongation factor-G (EF-G) on the ribosome. Mutations in fusA, the gene encoding bacterial EF-G, confer hi...

Koripella, Srihari Nagendra Ravi Kiran

2013-01-01

204

Synthesis of Boron Carbide from Boric Acid and Carbon-Containing Precursors  

OpenAIRE

The paper compares low-temperature techniques for boron carbide synthesis. Boron carbide was syn-thesized via reaction between boric acid and various carbon precursors, e.g. phenol-formaldehyde resin, su-crose, carbon black, and potato starch. Initial compositions and carbon precursor preparation techniques were selected for synthesis. The resulting products were characterized by IR spectrometry, X-ray diffrac-tion (XRD) and scanning electron microscopy. Possible boron carbide yields up to 95...

Genusova T.N.; Zakharova K.; Mednikova A.; Rumyantsev V.

2013-01-01

205

Solvent-free lipase-catalyzed synthesis of a novel hydroxyl-fatty acid derivative of kojic acid.  

Science.gov (United States)

The aim of this work was the synthesis of a novel hydroxyl-fatty acid derivative of kojic acid rich in kojic acid monoricinoleate (KMR) which can be widely used in the cosmetic and food industry. The synthesis of KMR was carried out by lipase-catalysed esterification of ricinoleic and kojic acids in solvent-free system. Three immobilized lipases were tested and the best KMR yields were attained with Lipozyme TL IM and Novozym 435. Since Lipozyme TL IM is the cheapest, it was selected to optimize the reaction conditions. The optimal reaction conditions were 80 °C for the temperature, 1:1 for the alcohol/acid molar ratio, 600 rpm for stirring speed and 7.8% for the catalyst concentration. Under these conditions, the reaction was scaled up in a 5×10?³ m³ stirred tank reactor. ¹H-¹³C HMBC-NMR showed that the primary hydroxyl group of kojic acid was regioselectively esterified. The KMR has more lipophilicity than kojic acid and showed antioxidant activity that improves the oxidation stability of biodiesel. PMID:24411455

El-Boulifi, Noureddin; Ashari, Siti Efliza; Serrano, Marta; Aracil, Jose; Martínez, Mercedes

2014-02-01

206

Synthesis of ester-linked lithocholic acid dimers.  

Science.gov (United States)

Four lithocholic acid dimers were synthesised via esterification. The ester-linked dimer, 3-oxo-5beta-cholan-24-oic acid (cholan-24-oic acid methyl ester)-3-yl ester, (3alpha,5beta), was obtained by condensation of methyl lithocholate with 3-oxo-5beta-cholan-24-oic acid. Borohydride reduction of this ester-linked dimer gave 3alpha-hydroxy-5beta-cholan-24-oic acid (cholan-24-oic acid methyl ester)-3-yl ester, (3alpha,5beta), which was acetylated to 3alpha-acetoxy-5beta-cholan-24-oic acid (cholan-24-oic acid methyl ester)-3-yl ester, (3alpha,5beta). Reaction of methyl lithocholate with oxalyl chloride yielded the oxalate dimer, bis(5beta-cholan-24-oic acid methyl ester)-3alpha-yl oxalate. PMID:14643877

Nahar, Lutfun; Turner, Alan B

2003-12-01

207

Effect of retinoic acid on melanoma cell-derived factor stimulation of fibroblast glycosaminoglycan synthesis.  

Science.gov (United States)

The hyaluronan-rich matrix that surrounds many tumours and facilitates tumour cell growth and invasion is thought to be predominantly synthesized by normal stromal cells stimulated by tumour cell-derived factors. This study examines the possibility that the production of tumour cell-derived factors that stimulate fibroblast glycosaminoglycan (GAG) synthesis may be blocked by exposure to differentiation-inducing agents such as retinoic acid. We have demonstrated that Hs294T, C8161 and A375 human melanoma cell lines release factors into their medium that stimulate normal fibroblast GAG synthesis. Exposure of these melanoma cells to retinoic acid failed to mediate any significant reduction in growth over a 7-day period. Retinoic acid failed to block the tumour cell production of GAG-stimulating activities and even enhanced the activities produced by the C8161 cell line, particularly at low retinoic acid concentrations (48% stimulation at 10(-9) M retinoic acid; P < 0.02). Addition of retinoic acid directly to fibroblast cultures exposed to fibroblast-conditioned medium resulted in an inhibition of GAG synthesis with a 33% inhibition observed at 10(-5) M. Addition of retinoic acid to fibroblast cultures exposed to the tumour cell-conditioned medium failed to inhibit the stimulation of GAG synthesis. Other differentiation-inducing agents, such as hexamethylene-bis-acetamide and butyrate, also failed to block the production of tumour cell-derived GAG-stimulating activities. These results demonstrate that retinoic acid and other differentiation-inducing agents fail to inhibit melanoma cell production of fibroblast GAG synthesis-stimulating factors or their action upon fibroblasts. PMID:9195557

Edward, M; Godden, J L; Alexander, C L; MacKie, R M

1997-06-01

208

Synthesis of [1-{sup 11}C]-2-octynoic acid, [1-{sup 11}C]-2-decynoic acid and [1-{sup 11}C]-3-(R,S)-methylocatanoic acid  

Energy Technology Data Exchange (ETDEWEB)

[1-{sup 11}C]-2-Octynoic acid, [1-{sup 11}C]-2-decynoic acid and [1-{sup 11}C]-3-(R,S)-methyloctanoic acid have been synthesized in order to evaluate these compounds as PET (Positron Emission Tomography) tracers for imaging in vivo medium-chain acyl-CoA dehydrogenase and medium-chain fatty acid utilization. The synthesis was performed by the Grignard reaction between alkylmagnesium bromides and [{sup 11}C]CO{sub 2}. The radiochemical yields of [1-{sup 11}C]-2-octynoic acid, [1-{sup 11}C]-2-decynoic acid, and [1-{sup 11}C]-3-(R,S)-methyloctanoic acid were 10, 7 and 1% based on the [{sup 11}C]CO{sub 2} used, respectively. Radiochemical purity was >99% in all cases. (UK).

Kawashima, Hidefumi; Yajima, Kazuyoshi; Kuge, Yuji; Hashimoto, Naoto; Miyake, Yoshihiro [National Cardiovascular Center, Osaka (Japan). Institute for Biofunctional Research Co. Ltd.

1997-03-01

209

Epoxy Resin and Polyurethane Compositions from Glycolized Poly (ethylene terephthalate Wastes  

Directory of Open Access Journals (Sweden)

Full Text Available The possibility to use poly(ethylene terephthalate (PET bottles production waste as raw material for compositions with high adhesion ability has been investigated. PET waste was glycolyzed with polypropylene glycol and three kinds of oligoesters were formed after depolymerization reaction. The polydispersity of product formed was 1.05. The possibilities to use PET glycolysis products – oligoesters for epoxy resin and polyurethanes were studied. Two-step reaction of oligoesters with epichlorohydrin was chosen for epoxy resin synthesis, while glycolyzed PET reaction with aliphatic isocyanate was used for polyurethane synthesis. The structure and properties of the obtained polymers were investigated. DOI: http://dx.doi.org/10.5755/j01.ms.19.3.5237

Gintaras MACIJAUSKAS

2013-09-01

210

Synthesis of sup(123m)Te labeled fatty acids  

International Nuclear Information System (INIS)

Four sup(123m)Te labeled fatty acid analogues were synthesized: 17-tellura-9-octadecenoic acid, 17-tellura-9-nonadecenoic acid, 18-methyl-17-tellura-9-nonadecenoic acid and 3-tellura-nonadecanoic acid. Tellurium-123m metal was solubilized in water with NaBH4. The inorganic nucleophiles produced, NaHTe or Na2Te2 were reacted with 16-bromo-9-hexadecenoic acid in a one or two step procedure to produce the sodium alkyl telluride. To this was added either methyl iodide, ethyl bromide or isopropyl bromide and the resulting 17-tellura-fatty acids isolated and formulated. Tellurium-123m labeled 3-tellura-nonadecanoic acid was synthesized via the dihexadecanyl ditelluride or the sodium hexadecanyl telluride route. (author)

211

A convenient procedure for the solid-phase synthesis of hydroxamic acids on PEGA resins  

DEFF Research Database (Denmark)

An efficient method for the solid-phase synthesis of hydroxamic acids is described. The method comprises the nucleophilic displacement of esters immobilized on PEGA resins with hydroxylamine/sodium hydroxide in isopropanol. The hydroxyaminolysis protocol is compatible with a broad range of PEGA-supported peptide and peptidomimetic esters. The methodology was found to be compatible with two new strategies for the synthesis of solid-supported lactams and diketopiperazines, respectively, both relying on the high inter- and intramolecular reactivity of cyclic N-acyliminium ions with electron-rich aromatics and heteroaromatics, ultimately affording hydroxamic acid derivatives in high purities.

Nandurkar, Nitin Subhash; Petersen, Rico

2011-01-01

212

Camphor Sulfonic Acid-hydrochloric Acid Codoped Polyaniline/polyvinyl Alcohol Composite: Synthesis and Characterization  

Scientific Electronic Library Online (English)

Full Text Available Se utilizó un sistema de dopaje complementario formado por ácido clorhídrico y ácido canforsulfónico (ACS) en la síntesis in-situ de un material compuesto polianilina (PANI)/alcohol polivi-nílico (APV). Las mediciones de conductividad mostraron que el uso de ACS ya sea como dopante o codopante resul [...] tó en un decremento en la conductividad total de hasta 2 órdenes de magnitud así como una mejora en la estabilidad térmica. Los compósitos PANi/APV fueron caracterizados mediante análisis térmicos y espectroscópicos. La formación de la sal esmeraldina conductora fue confirmada por espectroscopia UV-Visible e Infrarroja de Transformada de Fourier. El análisis microestructural se llevó a cabo por MEB. Abstract in english A complementary dopant system formed by hydrochloric and camphor sulfonic (CSA) acids was used in the in-situ synthesis of a polyaniline (PANi)/polyvinyl alcohol (PVA) composite. The conductivity measurements showed that the use of CSA either as single dopant or codopant caused a decrement up to 2 o [...] rders of magnitude on the overall conductivity as well as an improvement on thermal stability. The PANi/PVA composites were characterized by spectro-scopic and thermal analysis. Conducting emeraldine salt formation was confirmed by UV-VIS and FTIR spectroscopy. Microstructure analysis was performed by SEM imaging.

Jorge Enrique, Osorio-Fuente; Carlos, Gómez-Yáñez; María de los Ángeles, Hernández-Pérez; Fidel, Pérez-Moreno.

2014-03-01

213

Kinetics of Ethyl Acetate Synthesis Catalyzed by Acidic Resins  

Science.gov (United States)

A low-cost experiment to carry out the second-order reversible reaction of acetic acid esterification with ethanol to produce ethyl acetate is presented to illustrate concepts of kinetics and reactor modeling. The reaction is performed in a batch reactor, and the acetic acid concentration is measured by acid-base titration versus time. The…

Antunes, Bruno M.; Cardoso, Simao P.; Silva, Carlos M.; Portugal, Ines

2011-01-01

214

Emanation thermal analysis for characterizing diffusion properties of Ba-phthalate, -isophthalate and -terephthalate  

International Nuclear Information System (INIS)

Emanation thermal analysis (ETA) is used for characterizing Ba-salts of phthalic, isophthalic and terephthalic acids. It is shown that the emanation thermal characteristics measured in the temperature range between 298 and 373 K are suitable for estimating diffusion properties of studied organic solids. The ETA results are supplied by TG/DTG and DTA curves and surface area measurements. An apparatus for determining emanation-thermal characteristics is proposed. Thorium-228 and radium-224 are used for labelling. The released radon is measured by scintillation counting

215

Determination of potential migrants from commercial amber polyethylene terephthalate bottle wall.  

Science.gov (United States)

Potential migrants were isolated from commercial polyethylene terephthalate (PET) bottles using Soxhlet extraction. The concentrated extract was then subjected to GC/MS analysis. A total of 19 migrants has been identified. The majority of compounds appeared to be intermediate reaction products or residual monomers of their dehydration and transesterification products. Several processing aids such as fatty acids and commonly used plasticizers were also identified. The amount of seven compounds present in the major portion of exhaustive extract of the PET bottle wall ranged from 800 micrograms/g polymer to as low as 0.6 microgram/g. PMID:2137912

Kim, H; Gilbert, S G; Johnson, J B

1990-02-01

216

Characterization of the Terephthalate Degradation Genes of Comamonas sp. Strain E6  

OpenAIRE

We isolated Comamonas sp. strain E6, which utilizes terephthalate (TPA) as the sole carbon and energy source via the protocatechuate (PCA) 4,5-cleavage pathway. Two almost identical TPA degradation gene clusters, tphRICIA2IA3IBIA1I and tphRIICIIA2IIA3IIBIIA1II, were isolated from this strain. Based on amino acid sequence similarity, the genes tphR, tphC, tphA2, tphA3, tphB, and tphA1 were predicted to code, respectively, for an IclR-type transcriptional regulator, a periplasmic TPA binding re...

Sasoh, Mikio; Masai, Eiji; Ishibashi, Satoko; Hara, Hirofumi; Kamimura, Naofumi; Miyauchi, Keisuke; Fukuda, Masao

2006-01-01

217

Synthesis of aliphatic polyesters by polycondensation using inorganic acid as catalyst  

OpenAIRE

An effective route for the synthesis of aliphatic polyesters made from adipic or sebacic acid and alkanediols, using inorganic acid as a catalyst is reported. The monomer composition, reaction time, catalyst type, and reaction conditions were optimized to yield polyesters with weight average molecular weights of 23,000 for adipic acid and 85,000 for sebacic acid-based polyesters. The polymers melt at temperatures of 52–65°C and possess melt viscosity in the range of 5600–19,400cP. This r...

Sokolsky-papkov, Marina; Langer, Robert; Domb, Abraham J.

2009-01-01

218

Synthesis of aliphatic polyesters by polycondensation using inorganic acid as catalyst.  

Science.gov (United States)

An effective route for the synthesis of aliphatic polyesters made from adipic or sebacic acid and alkanediols, using inorganic acid as a catalyst is reported. The monomer composition, reaction time, catalyst type, and reaction conditions were optimized to yield polyesters with weight average molecular weights of 23,000 for adipic acid and 85,000 for sebacic acid-based polyesters. The polymers melt at temperatures of 52-65°C and possess melt viscosity in the range of 5600-19,400cP. This route represents an alternative method for producing aliphatic polyesters for possible use in the preparation of degradable disposable medical supplies. PMID:25473252

Sokolsky-Papkov, Marina; Langer, Robert; Domb, Abraham J

2011-04-01

219

Síntese de glicoaminoácidos de interesse biológico / Synthesis of glycosyl-amino acids of biological interest  

Scientific Electronic Library Online (English)

Full Text Available [...] Abstract in english This work describes the synthesis of the glycosylated amino acids ?GlcNAc-Thr, ?GlcNAc-Thr and ?LacNAc-Thr by the glycosylation reaction of the amino acid threonine with the corresponding glycosyl donors ?GlcNAcCl and ?LacN3Cl. The glycosylated amino acids containing the sugar units ?-D-GlcNAc and ? [...] -D-LacNAc O-linked to threonine amino acids are related to O-glycans found in mucins of the parasite Trypanosoma cruzi, while the corresponding ?-D-GlcNAc isomer is involved in cellular signaling events.

Vanessa Leiria, Campo; Ivone, Carvalho.

1027-10-01

220

Reciclagem química do PET pós-consumo: caracterização estrutural do ácido tereftálico e efeito da hidrólise alcalina em baixa temperatura / Chemical Recycling of Post-consumer PET: Structural characterization of terephthalic acid and the effect of Alkaline Hydrolysis at low temperature  

Scientific Electronic Library Online (English)

Full Text Available Devido ao impacto ambiental causado pelo descarte de embalagens PET, a reciclagem desse material tem sido bastante discutida e avaliada. Em particular, a reciclagem química viabiliza a obtenção dos monômeros utilizados na fabricação da resina PET: o etilenoglicol (EG) e o ácido tereftálico (PTA). Po [...] r isso, estudos de otimização desse processo são importantes tanto do ponto de vista ambiental, quanto econômico. Neste trabalho foram investigados certos parâmetros que influenciam a reação de despolimerização do PET pós-consumo via hidrólise alcalina, a fim de obter o PTA. Os ensaios foram realizados à temperatura de 70 °C, variando a concentração da solução de hidróxido de sódio e o tempo de reação. Os melhores resultados foram obtidos para concentração de NaOH 10,82 mol L-1 e tempo de reação de 9 h. Consequentemente, foi possível comprovar a viabilidade do processo, uma vez que as análises por infravermelho e Ressonância Magnética Nuclear confirmaram a obtenção do PTA em todas as reações realizadas. Abstract in english Due to the environmental impact caused by PET packaging disposal, this material recycling has been thoroughly discussed and evaluated. In particular, chemical recycling enables achievement of the monomers that are used in PET resin manufacture: ethylene glycol (EG) and terephthalic acid (PTA). There [...] fore, studies for this process optimization are important from environmental and economic points of view. The present study investigated certain parameters that influence the depolymerization reaction of PET post-consumer via alkaline hydrolysis in order to obtain PTA. Assays were performed at 70 °C by varying the concentration of sodium hydroxide and the reaction time. The best results were obtained at 10.82 mol L-1 NaOH and 9 h reaction time. Consequently, it was possible to prove this process viability, once analyses by infrared and nuclear magnetic resonance confirmed that PTA was obtained in all reactions performed.

Talitha Granja, Fonseca; Yeda Medeiros Bastos de, Almeida; Glória Maria, Vinhas.

2014-10-01

221

Mutants of Escherichia coli with cold-sensitive deoxyribonucleic acid synthesis.  

Science.gov (United States)

Ten cold-sensitive mutants defective in deoxyribonucleic acid (DNA) synthesis at 20 C have been identified among 218 cold-sensitive mutants isolated from a mutagenized population of Escherichia coli K-12. Four of the ten mutant alleles, dna-339 dna-340, dna-341, and dna-342, cotransduce with serB(+) and hence may be dnaC mutants. Two of these, dna-340 and dna-341, are recessive to their wild-type allele. The gene product of their wild-type allele is trans acting. Complementation tests have demonstrated that dna-340 and dna-341 are in the same cistron. The mapping of the remaining six mutations is in progress. In an attempt to determine whether LW4 and LW21 were initiator mutants, cultures of these strains were starved of an essential amino acid at 37 C and then incubated at 15 C with the essential amino acid. The amount of DNA synthesis observed under these circumstances was insignificant. These data are consistent with the idea that LW4 and LW21 are initiator mutants. However, attempts to integratively suppress LW4 and LW21 with F' factors were unsuccessful. To resolve the question of whether or not LW4 and LW21 are initiator mutants, more specific tests and criteria are required. Cultures of LW4 and LW21 were toluene treated and used to measure in vitro DNA synthesis. If the cells were incubated either at 15 or 20 C before toluene treatment, they were capable of markedly less DNA synthesis than if preincubation had not occurred. The amount of in vitro DNA synthesis is directly proportional to the amount of DNA synthesis occurring during preincubation in vivo; i.e., more DNA synthesis is observed at 20 than at 15 C. The fact that the cold-sensitive mutants are unable to synthesize DNA when supplied with deoxyribonucleoside triphosphates, DNA precursors, is evidence they are not defective in precursor synthesis. PMID:4597994

Waskell, L; Glaser, D A

1974-06-01

222

Relationship of lipogenic enzyme activities to the rate of rat liver fatty acid synthesis  

International Nuclear Information System (INIS)

The mechanism by which diet regulates liver lipogenesis is unclear. Here the authors report how dietary alterations effect the activities of key enzymes of fatty acid (FA) synthesis. Male Sprague-Dawley rats, 400-500 g, were fasted for 48h and then refed a fat-free, high carbohydrate (HC) diet (75% cal. from sucrose) for 0,3,9,24 and 48h, or refed a HC diet for 48h, then fed a high-fat (HF) diet (44% cal. from corn oil) for 3,9,24 and 48h. The FA synthesis rate and the activities of acetyl CoA carboxylase (AC), fatty acid synthase (FAS), ATP citrate lyase (CL), and glucose 6-phosphate dehydrogenase (G6PDH) were determined in the livers. FA synthesis was assayed with 3H2O, enzyme activities were measured spectrophotometrically except for AC which was assayed with 14C-bicarbonate. There was no change in the activity of AC during fasting or on the HC diet. Fasting decreased the rate of FA synthesis by 25% and the activities of FAS and CL by 50%; refeeding the HC diet induced parallel changes in FA synthesis and the activities of FAS, CL, and G6PDH. After 9h on the HF diet, FA synthesis had decreased sharply, AC activity increased significantly while no changes were detected in the other activities. Subsequently FA synthesis did not change while the activities of the enzymes decreased slowly. These enzymes did not appear to regulate FA synthesis during inhibition of lipogenesis, but FAS, CL or G6PDH may be rate limiting in the induction phase. Other key factors may regulate FA synthesis during dietary alterations

223

Increased Production of Fatty Acids and Triglycerides in Aspergillus oryzae by Enhancing Expressions of Fatty Acid Synthesis-Related Genes  

Energy Technology Data Exchange (ETDEWEB)

Microbial production of fats and oils is being developedas a means of converting biomass to biofuels. Here we investigate enhancing expression of enzymes involved in the production of fatty acids and triglycerides as a means to increase production of these compounds in Aspergillusoryzae. Examination of the A.oryzaegenome demonstrates that it contains twofatty acid synthases and several other genes that are predicted to be part of this biosynthetic pathway. We enhancedthe expressionof fatty acid synthesis-related genes by replacing their promoters with thepromoter fromthe constitutively highly expressedgene tef1. We demonstrate that by simply increasing the expression of the fatty acid synthasegenes we successfullyincreasedtheproduction of fatty acids and triglyceridesby more than two fold. Enhancement of expression of the fatty acid pathway genes ATP-citrate lyase and palmitoyl-ACP thioesteraseincreasedproductivity to a lesser extent.Increasing expression ofacetyl-CoA carboxylase caused no detectable change in fatty acid levels. Increases in message level for each gene were monitored usingquantitative real-time RT-PCR. Our data demonstrates that a simple increase in the abundance of fatty acid synthase genes can increase the detectable amount of fatty acids.

Tamano, Koichi; Bruno, Kenneth S.; Karagiosis, Sue A.; Culley, David E.; Deng, Shuang; Collett, James R.; Umemura, Myco; Koike, Hideaki; Baker, Scott E.; Machida, Masa

2013-01-01

224

Thorium Terephthalates Coordination Polymers Synthesized in Solvothermal DMF/H2O System.  

Science.gov (United States)

A series of thorium-based terephthalates have been solvothermaly synthesized in N,N-dimethylformamide (DMF) with different amounts of water and various temperatures (100-150 °C). Without the addition of water, the Th-H2bdc-DMF system gives rise to the formation of two phases, Th(bdc)2(DMF)2 (1) and Th6O4(OH)4(H2O)6(bdc)6·6DMF·12H2O (3) (bdc = 1,4-benzenedicarboxylate or terephthalate). Their structures are built up of isolated thorium centers ThO8(DMF)2 for (1) and the hexanuclear core Th6O4(OH)4(H2O)6 for (3). The latter adopts the UiO-66 metal-organic framework topology and exhibits a very high porosity for an actinides-based porous material (BET surface up to 730(6) m(2)·g(-1)). The synthesis of (3) is also favored upon adding water. However, for pure aqueous solutions or for a very low amount of water, a third solid Th(bdc)2 (2) crystallizes and contains thorium monomers ThO8. The main similitude with the parent system dedicated to tetravalent uranium concerns the possibility to stabilize the An6O8(H2O)6 core by terephthalate linkers and to reproduce An(bdc)2(DMF)2 for both actinides U(4+) and Th(4+). The thermal treatment of the latter shows a structural transition into the crystalline Th(bdc)2 (2) solid. PMID:25668215

Falaise, Clément; Charles, Jean-Sébastien; Volkringer, Christophe; Loiseau, Thierry

2015-03-01

225

Somatostatin inhibits gastric acid secretion after gastric mucosal prostaglandin synthesis inhibition by indomethacin in man.  

OpenAIRE

The inhibitory effect of indomethacin, 200 + 200 mg administered per os over 24 hours, on the prostaglandin E2 generative capacity of gastric mucosal tissue was determined in healthy male volunteers. The effect of prostaglandin synthesis inhibition on somatostatin induced suppression of food-stimulated acid secretion was tested. Peptone meal stimulated acid secretion was quantified in five healthy volunteers by intragastric titration with and without indomethacin pretreatment. Somatostatin do...

Mogard, M. H.; Maxwell, V.; Kovacs, T.; Deventer, G.; Elashoff, J. D.; Yamada, T.; Kauffman, G. L.; Walsh, J. H.

1985-01-01

226

SYNTHESIS OF TRIFLUOROMETHYL-IMINES BY SOLID ACID/SUPERACID CATALYZED MICROWAVE ASSISTED APPROACH  

OpenAIRE

A new solid acid/superacid catalyzed microwave assisted synthesis of trifluoromethyl-imines is described. Various ?,?,?-trifluoromethylketones react readily with primary amines to produce the corresponding imines. Two different strategies have been employed; one is the application of microwave irradiation coupled with solvent-free solid acid catalysis. The other method, for highly deactivated substrates includes the use of a pressure vessel at 175 °C temperature, with solid superacid cata...

Abid, Mohammed; Savolainen, Markku; Landge, Shainaz; Hu, Jinbo; Surya Prakash, G. K.; Olah, George A.; To?ro?k, Be?la

2007-01-01

227

5[prime] to 3[prime] nucleic acid synthesis using 3[prime]-photoremovable protecting group  

Science.gov (United States)

The present invention relates, in general, to a method of synthesizing a nucleic acid, and, in particular, to a method of effecting 5[prime] to 3[prime] nucleic acid synthesis. The method can be used to prepare arrays of oligomers bound to a support via their 5[prime] end. The invention also relates to a method of effecting mutation analysis using such arrays. The invention further relates to compounds and compositions suitable for use in such methods.

Pirrung, M.C.; Shuey, S.W.; Bradley, J.C.

1999-06-01

228

5'to 3' nucleic acid synthesis using 3'-photoremovable protecting group  

Science.gov (United States)

The present invention relates, in general, to a method of synthesizing a nucleic acid, and, in particular, to a method of effecting 5' to 3' nucleic acid synthesis. The method can be used to prepare arrays of oligomers bound to a support via their 5' end. The invention also relates to a method of effecting mutation analysis using such arrays. The invention further relates to compounds and compositions suitable for use in such methods.

Pirrung, Michael C. (Houston, TX); Shuey, Steven W. (Durham, NC); Bradley, Jean-Claude (Durham, NC)

1999-01-01

229

Synthesis of 14C-labeled halogen substituted indole-3-acetic acids  

International Nuclear Information System (INIS)

A general method for microscale synthesis of 14C-labeled indole-3-acetic acids with halogen substitutions in the benzene ring is described. The method utilizes halogen substituted phenylhydrazines reacted with [14C]-2-oxoglutarate to generate the halogenated indole-3-acetic acid. 3-Chlorophenyl-hydrazine yielded a mixture of the 4 and 6 chloro compounds that was resolved by C18-reverse phase high performance liquid chromatography. (author)

230

Glycomimetic building blocks: a divergent synthesis of epimers of shikimic acid  

Science.gov (United States)

A divergent synthesis of (?)-4-epi-shikimic acid was developed. This route features a one-pot zinc-mediated reductive ring opening of an arabinofuranose followed by a Barbier reaction and culminates in a ring-closing metathesis. Functionalization of (?)-4-epi-shikimic acid via conjugate addition of a thiol occurs in high diastereoselectivity to afford a product with the features of fucosylated glycans. PMID:21711006

Grim, Joseph C.; Garber, Kathleen C. A.

2011-01-01

231

Synthesis of 2-[11C]cyano-isonicotinic acid hydrazide  

International Nuclear Information System (INIS)

Isonicotinic acid hydrazide (isoniazid), a drug used in treating tuberculosis has been labelled with carbon-11 at the 2-position. The labelling synthesis starts with methyl isonicotinate treated with dimethyl sulfate. The resulting salt solution is loaded onto silica gel and dried, followed by treatment with carbon-11 labelled hydrocyanic acid. Work-up gave the labelled compound with an average 32% radiochemical yield. Subsequent treatment with hydrazine hydrate yielded isoniazid

232

Synthesis and Reactivity of alpha-Trialkylsilyl alpha-Amino Acids  

OpenAIRE

This work deals with the synthesis and reactivity of alpha-trialkylsilyl alpha-amino acids. They were synthesised using an established protocol involving rhodium(II)-catalysed insertion reactions of alpha-trialkylsilyl alpha-diazo esters into N-H bonds of carbamates. As an extension to this procedure, it was accounted that a diastereoselective approach to N-protected alpha-trialkylsilyl alpha-amino acids precursors may lead, after deprotection, to the formation of enantiomerically-pure alpha-...

Veri, Elisabetta

2006-01-01

233

Organocatalysed multicomponent synthesis of pyrazolidinones: Meldrum's acid approach.  

Science.gov (United States)

We discovered a novel organocatalysed multicomponent domino Knoevenagel-aza-Michael-cyclocondensation reaction leading to an unprecedented straightforward synthesis of 1,5-diazabicyclo[3.3.0]octane-2,6-diones. The specific capability of the (DHQ)2PHAL organocatalyst in this process was also highlighted to eventually furnish the corresponding bicyclopyrazolidinones with up to 96?:?4 er. PMID:25056763

Pair, Etienne; Berini, Christophe; Noël, Romain; Sanselme, Morgane; Levacher, Vincent; Brière, Jean-François

2014-09-14

234

Photochemical Synthesis of the Bioconjugate Folic Acid-Gold Nanoparticles  

OpenAIRE

In this paper we present a rapid and simple onepot method to obtain gold nanoparticles functionalized with folic acid using a photochemistry method. The bioconjugate folic acid-gold nanoparticle was generated in one step using a photo-reduction method, mixing hydrogen tetrachloroaurate with folic acid in different ratios and varying the illumination time of a mercury lamp (?= 255 nm). Scanning electron microscopy showed a particle size of around 40-50nm and dynamic li...

John Castillo; Linda Bertel; Edgar Páez-Mozo; Fernando Martínez

2013-01-01

235

Cesium salts of phosphotungstic acid: Comparison of surface acidity, leaching stability and catalytic activity for the synthesis of ?-ketoenol ethers  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Catalytic activity of Cs xH3-xPW12O40 catalysts were investigated in the synthesis of ?-ketoenol ethers. It was found that activity; acidity, solubility and consequently, recoverability of these catalysts are related to cesium content. A series of ?-ketoenol ether derivatives were synthesized by usi [...] ng Cs25H0.5PW12O40 catalyst in high to excellent yields. This catalyst showed highest surface acidity and lowest solubility in reaction media in comparison with the other cesium content salts.

Ezzat, Rafiee; Masoud, Kahrizi.

2013-08-01

236

Cesium salts of phosphotungstic acid: Comparison of surface acidity, leaching stability and catalytic activity for the synthesis of ?-ketoenol ethers  

Scientific Electronic Library Online (English)

Full Text Available Catalytic activity of Cs xH3-xPW12O40 catalysts were investigated in the synthesis of ?-ketoenol ethers. It was found that activity; acidity, solubility and consequently, recoverability of these catalysts are related to cesium content. A series of ?-ketoenol ether derivatives were synthesized by usi [...] ng Cs25H0.5PW12O40 catalyst in high to excellent yields. This catalyst showed highest surface acidity and lowest solubility in reaction media in comparison with the other cesium content salts.

Ezzat, Rafiee; Masoud, Kahrizi.

2013-08-01

237

Synthesis of hyper branched polyol from palm oil oleic acid  

International Nuclear Information System (INIS)

Hyper branched polyol from oleic acid of palm oil has been synthesized by a two-step reaction. Dipentaerythritol was initially reacted with 2, 2-bis (hydroxymethyl) propionic acid in a solution medium aided by p-toluene sulfonic acid as a catalyst. This mixture was then used as core and reacted with the oleic acid. Optimization parameters such as processing temperature and reaction time, and chemical analysis (for example OHV, AV, FTIR, NMR and GPC) of the macromolecule synthesized is presented in this paper. (author)

238

Development of Escherichia coli MG1655 strains to produce long chain fatty acids by engineering fatty acid synthesis (FAS) metabolism.  

Science.gov (United States)

The goal of this research was to develop recombinant Escherichia coli to improve fatty acid synthesis (FAS). Genes encoding acetyl-CoA carboxylase (accA, accB, accC), malonyl-CoA-[acyl-carrier-protein] transacylase (fabD), and acyl-acyl carrier protein thioesterase (EC 3.1.2.14 gene), which are all enzymes that catalyze key steps in the synthesis of fatty acids, were cloned and over-expressed in E. coli MG1655. The acetyl-CoA carboxylase (ACC) enzyme catalyzes the addition of CO(2) to acetyl-CoA to generate malonyl-CoA. The enzyme encoded by the fabD gene converts malonyl-CoA to malonyl-[acp], and the EC 3.1.2.14 gene converts fatty acyl-ACP chains to long chain fatty acids. All the genes except for the EC 3.1.2.14 gene were homologous to E. coli genes and were used to improve the enzymatic activities to over-express components of the FAS pathway through metabolic engineering. All recombinant E. coli MG1655 strains containing various gene combinations were developed using the pTrc99A expression vector. To observe changes in metabolism, the in vitro metabolites and fatty acids produced by the recombinants were analyzed. The fatty acids (C16) from recombinant strains were produced 1.23-2.41 times higher than that from the wild type. PMID:22112270

Jeon, Eunyoung; Lee, Sunhee; Won, Jong-In; Han, Sung Ok; Kim, Jihyeon; Lee, Jinwon

2011-06-10

239

Easy synthesis of graphene sheets from alfalfa plants by treatment of nitric acid  

International Nuclear Information System (INIS)

Highlights: ? An easy method for synthesis of graphene sheets using alfalfa plants was introduced. ? An novelty formation mechanism of graphene sheets using alfalfa plants was proposed. ? This method exploits a new carbon source and provides a novel idea to synthesize graphene sheets. -- Abstract: This letter focuses on synthesis of graphene sheets from alfalfa plants by treatment of nitric acid. The transmission electron microscopy image (TEM) demonstrates that the graphene sheets are agglomerated and overlapped, the energy dispersive spectrum (EDS) indicates that the products are pure, and the Raman spectrum shows the graphene sheets are well graphitized. In addition, the formation mechanism of the graphene sheets from alfalfa plants by treatment nitric acid is discussed. These findings inspire the search for a new strategy for synthesis of graphene sheets from renewable natural products, and the lower cost of this new process and carbon source may facilitate industrial production

240

Easy synthesis of graphene sheets from alfalfa plants by treatment of nitric acid  

Energy Technology Data Exchange (ETDEWEB)

Highlights: ? An easy method for synthesis of graphene sheets using alfalfa plants was introduced. ? An novelty formation mechanism of graphene sheets using alfalfa plants was proposed. ? This method exploits a new carbon source and provides a novel idea to synthesize graphene sheets. -- Abstract: This letter focuses on synthesis of graphene sheets from alfalfa plants by treatment of nitric acid. The transmission electron microscopy image (TEM) demonstrates that the graphene sheets are agglomerated and overlapped, the energy dispersive spectrum (EDS) indicates that the products are pure, and the Raman spectrum shows the graphene sheets are well graphitized. In addition, the formation mechanism of the graphene sheets from alfalfa plants by treatment nitric acid is discussed. These findings inspire the search for a new strategy for synthesis of graphene sheets from renewable natural products, and the lower cost of this new process and carbon source may facilitate industrial production.

Qu, Jiao, E-mail: qujiao@bhu.edu.cn [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); School of Urban and Environmental Sciences, Northeast Normal University, Changchun 130024 (China); Luo, Chunqiu, E-mail: fplj_lcq@163.com [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); Zhang, Qian; Cong, Qiao [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); Yuan, Xing [School of Urban and Environmental Sciences, Northeast Normal University, Changchun 130024 (China)

2013-04-01

241

Studying synthesis kinetics of nanocomposite PANi/TiO2 in H2SO4 acid  

International Nuclear Information System (INIS)

Polyaniline (PANi) films have been electrochemically synthesized on stainless steel 316 L in H2SO4 acid solution using cyclic voltammetry. On the CV curve there are three oxidative potential regions. Adding nano titanium oxide in the solution affects strongly the synthesis process due to the formation of PANi/TiO2 nanocomposite. Kinetics of the synthesis reaction was studied basing on variation of the total anodic polarisation charges quantity Qa redox peaks parameters as anodic peak current JPa and electric quantity QPa and derivation dJ/dC for the entire synthesis ranges, in regard to the nano titanium oxide concentration. It was found that the kinetics of the synthesis reaction of the nanocomposite depends closely on the [TiO2] from 0 g/l to 5 g/l. (author)

242

Formic acid electro-synthesis from carbon dioxide in a room temperature ionic liquid.  

Science.gov (United States)

The novel synthesis of formic acid has been achieved in a room temperature ionic liquid via the reaction of electro-activated carbon dioxide and protons on pre-anodised platinum. Only mild reaction conditions of room temperature and 1 atm CO(2) were used. This work highlights the effect of pre-anodisation on Pt surfaces. PMID:22622393

Martindale, Benjamin C M; Compton, Richard G

2012-07-01

243

Formic acid electro-synthesis from carbon dioxide in a room temperature ionic liquid.  

OpenAIRE

The novel synthesis of formic acid has been achieved in a room temperature ionic liquid via the reaction of electro-activated carbon dioxide and protons on pre-anodised platinum. Only mild reaction conditions of room temperature and 1 atm CO(2) were used. This work highlights the effect of pre-anodisation on Pt surfaces.

Martindale, Bc; Compton, Rg

2012-01-01

244

Synthesis, Characterization, and Saccharide Binding Studies of Bile Acid ? Porphyrin Conjugates  

Directory of Open Access Journals (Sweden)

Full Text Available Synthesis and characterization of bile acid-porphyrin conjugates (BAPs are reported. Binding of saccharides with BAPs in aqueous methanol was studied by monitoring changes in the visible absorption spectral of the porphyrin-moieties. Although these studies clearly showed absorbance changes, suggesting quite high if non-selective binding, the mass spectral studies do not unambiguously support these results.

Vladimír Král

2007-01-01

245

Synthesis, Characterization, and Saccharide Binding Studies of Bile Acid ? Porphyrin Conjugates  

OpenAIRE

Synthesis and characterization of bile acid-porphyrin conjugates (BAPs) are reported. Binding of saccharides with BAPs in aqueous methanol was studied by monitoring changes in the visible absorption spectral of the porphyrin-moieties. Although these studies clearly showed absorbance changes, suggesting quite high if non-selective binding, the mass spectral studies do not unambiguously support these results.

Vladimír Král; Erkki Kolehmainen; Elina Sievänen; Juha Koivukorpi

2007-01-01

246

Synthesis, Characterization, and Saccharide Binding Studies of Bile Acid − Porphyrin Conjugates  

OpenAIRE

Synthesis and characterization of bile acid-porphyrin conjugates (BAPs) are reported. Binding of saccharides with BAPs in aqueous methanol was studied by monitoring changes in the visible absorption spectral of the porphyrin-moieties. Although these studies clearly showed absorbance changes, suggesting quite high if non-selective binding, the mass spectral studies do not unambiguously support these results.

Vladimír Král; Erkki Kolehmainen; Elina Sievänen; Juha Koivukorpi

2007-01-01

247

Tannic acid Catalyzed an Efficient Synthesis of 2,4,5-Triaryl-1H-Imidazole  

Directory of Open Access Journals (Sweden)

Full Text Available Tannic acid (C76H52O46 has been found to be an efficient catalyst for one-pot synthesis of 2,4,5-triaryl substituted imidazoles by the reaction of an arylaldehyde, benzyl/benzoin and an ammonium acetate. The short reaction time and excellent yields making this protocol practical and economically attractive.

Shitole Nana Vikram

2013-05-01

248

Synthesis of 2,2'-Dipyrryl Ketones from Pyrrole-2-carboxylic Acids with Trifluoroacetic Anhydride  

International Nuclear Information System (INIS)

An efficient synthesis of 2,2'-dipyrryl ketones has been carried out from pyrrole-2-carboxylic acids using trifluoroacetic anhydride (TFAA). Simultaneous generation of both mixed anhydride and 2-unsubstituted pyrrole, via facile decarboxylation with in-situ generated TFA, made their cross reaction (intermolecular Friedel-Crafts acylation) possible and efficient

249

(Het)aroylpyruvic acids and their derivatives as promising building blocks for organic synthesis  

Energy Technology Data Exchange (ETDEWEB)

Methods of synthesis of (het)aroylpyruvic acids and their acyclic derivatives (esters, amides and hydrazides), and their reactions with various C-, N-, O-, S-nucleophiles are described. Problems of tautomerism and biological activity of (het)aroylpyruvates and products of their transformation are briefly considered. The bibliography includes 191 references.

Perevalov, Sergei G; Burgart, Yanina V; Saloutin, Viktor I; Chupakhin, Oleg N [I. Ya. Postovsky Institute of Organic Synthesis, Urals Branch of the Russian Academy of Sciences, Ekaterinburg (Russian Federation)

2001-11-30

250

(Het)aroylpyruvic acids and their derivatives as promising building blocks for organic synthesis  

International Nuclear Information System (INIS)

Methods of synthesis of (het)aroylpyruvic acids and their acyclic derivatives (esters, amides and hydrazides), and their reactions with various C-, N-, O-, S-nucleophiles are described. Problems of tautomerism and biological activity of (het)aroylpyruvates and products of their transformation are briefly considered. The bibliography includes 191 references.

251

POLYSTYRENE SULFONIC ACID CATALYZED GREENER SYNTHESIS OF HYDRAZONES IN AQUEOUS MEDIUM USING MICROWAVES  

Science.gov (United States)

An environmentally benign aqueous protocol for the synthesis of cyclic, bi-cyclic, and heterocyclic hydrazones using polystyrene sulfonic acid (PSSA) as a catalyst has been developed; the simple reaction proceeds efficiently in water in the absence of any organic solvent under mi...

252

Synthesis of the ?-D-glucosyl ester of [carbonyl-13C]-indole-3-acetic acid  

International Nuclear Information System (INIS)

An efficient, operationally simple synthetic approach to 1-O-([carbonyl-13C]-indole-3'-ylacetyl)-?-D-glucopyranose is described. The synthesis was carried out by fusing a fully benzylated 1-O-glucosylpseudourea intermediate with [carbonyl-13C]-indole-3-acetic acid, followed by hydrogenolytic removal of the protective groups. (Author)

253

Phosphotungstic Acid: An Efficient, Cost-effective and Recyclable Catalyst for the Synthesis of Polysubstituted Quinolines  

Directory of Open Access Journals (Sweden)

Full Text Available Phosphotungstic acid (H3PW12O40 was used as an efficient and recyclable catalyst for the synthesis of polysubstituted quinolines through the Friedländer condensation of 2-aminoarylketone with carbonyl compounds, which was achieved by conventional heating under solvent-free conditions.

Sahareh Bashiribod

2009-03-01

254

Oxidative allylic rearrangement of cycloalkenols: Formal total synthesis of enantiomerically pure trisporic acid B  

Directory of Open Access Journals (Sweden)

Full Text Available Enantiomerically highly enriched unsaturated ?-ketoesters bearing a quaternary stereocenter can be utilized as building blocks for the synthesis of natural occurring terpenes, i. a., trisporic acid and its derivatives. An advanced building block has been synthesized in a short reaction sequence, which involves an oxidative allylic rearrangement initiated by pyridinium dichromate (PDC as the key step.

Bernhard Westermann

2011-04-01

255

Synthesis and biological evaluation of new salicylate macrolactones from anacardic acids  

International Nuclear Information System (INIS)

In connection with our ongoing investigation in the search for new bioactive compounds using non-isoprenoid phenolic lipids from Anacardium occidentale as starting material, we describe the synthesis and cytotoxicity screening of some novel salicylate macrolactones prepared from anacardic acids, the major constituents of natural cashew nut-shell liquid (CNSL). (author)

256

Conversion of pollutants to fertilisers: ion exchange synthesis of potassium sulphate from acidic mine waters.  

Science.gov (United States)

The paper reports the results obtained by the development of ion exchange synthesis of K2SO4 from the natural acidic mine waters (AMW) of Rio Tinto area (Huelva, Spain). The process flowsheet includes several sequential stages permitting production of potassium sulphate and desalinated water along with the recovery of four metals. PMID:12926638

Muraviev, D

2003-01-01

257

Synthesis of deuterated [D32 ]oleic acid and its phospholipid derivative [D64 ]dioleoyl-sn-glycero-3-phosphocholine.  

Science.gov (United States)

Oleic acid and its phospholipid derivatives are fundamental to the structure and function of cellular membranes. As a result, there has been increasing interest in the availability of their deuterated forms for many nuclear magnetic resonance, infrared, mass spectroscopy and neutron scattering studies. Here, we present for the first time a straightforward, large-scale (gram quantities) synthesis of highly deuterated [D32 ]oleic acid by using multiple, yet simple and high yielding reactions. The precursors for the synthesis of [D32 ]oleic acid are [D14 ]azelaic acid and [D17 ]nonanoic acid, which were obtained by complete deuteration (>98% D) of their (1) H forms by using metal catalysed hydrothermal H/D exchange reactions. The oleic acid was produced with ca. 94% D isotopic purity and with no contamination by the trans-isomer (elaidic acid). The subsequent synthesis of [D64 ]dioleoyl-sn-glycero-3-phosphocholine from [D32 ]oleic acid is also described. PMID:24285531

Darwish, Tamim A; Luks, Emily; Moraes, Greta; Yepuri, Nageshwar R; Holden, Peter J; James, Michael

2013-01-01

258

21 CFR 878.5000 - Nonabsorbable poly(ethylene terephthalate) surgical suture.  

Science.gov (United States)

...ethylene terephthalate) surgical suture. 878.5000 Section 878.5000 Food and Drugs FOOD AND DRUG ADMINISTRATION...PLASTIC SURGERY DEVICES Surgical Devices § 878.5000 Nonabsorbable poly(ethylene terephthalate)...

2010-04-01

259

76 FR 18519 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Amended Final Results of...  

Science.gov (United States)

...Terephthalate Film, Sheet, and Strip From Taiwan: Amended Final Results of Antidumping...sheet, and strip (PET Film) from Taiwan.\\1\\ The period of review (POR) is...Terephthalate Film, Sheet, and Strip From Taiwan: Final Results of Antidumping Duty...

2011-04-04

260

Synthesis of locked cyclohexene and cyclohexane nucleic acids (LCeNA and LCNA) with modified adenosine units.  

Science.gov (United States)

We describe here the preparation of conformationally locked cyclohexane nucleic acids designed as hybrids between locked nucleic acids (LNAs) and cyclohexene nucleic acids (CeNAs), both of which excel in hybridization with complementary RNAs. We have accomplished the synthesis of these adenine derivatives starting from a simple ketoester and installed all four chiral centres by means of total synthesis. The acquired monomers were incorporated into nonamer oligonucleotides. PMID:25594585

Šála, Michal; Dejmek, Milan; Procházková, Eliška; H?ebabecký, Hubert; Rybá?ek, Ji?í; Dra?ínský, Martin; Novák, Pavel; Rosenbergová, Šárka; Fukal, Ji?í; Sychrovský, Vladimír; Rosenberg, Ivan; Nencka, Radim

2015-02-18

261

Comparison of the effects of various amino acids on glycogen synthesis, lipogenesis and ketogenesis in isolated rat hepatocytes.  

OpenAIRE

Several amino acids were found to stimulate glycogen synthesis and lipogenesis, and to inhibit ketogenesis in isolated rat hepatocytes. When hepatocytes were incubated in the presence of 20 mM-glucose, the amino acids could be classified in decreasing order of efficiency as follows: glutamine and proline, alanine, aminoisobutyric acid, asparagine and histidine for stimulation of glycogen synthesis; glutamine, proline and alanine for stimulation of lipogenesis; proline and glutamine for inhibi...

Baquet, A.; Lavoinne, A.; Hue, Louis

1991-01-01

262

Synthesis of 2-naphtalene-d7-sulfonic acid  

International Nuclear Information System (INIS)

2-Naphthalene-d7-sulfonic acid, required as an internal standard for the analysis of organic compounds in water by gas chromatography/mass spectrometry, was synthesized in one step from commercially available naphthalene-d8 and sulfuric acid-d2. (author)

263

ACID CATALYZED SYNTHESIS OF HYPERBRANCHED POLY(GLYCEROL-DIACID) OLIGOMERS  

Science.gov (United States)

Novel oligomeric prepolymers were synthesized by acid-catalyzed condensation of glycerol with iminodiacetic, azelaic, or succinic acid. The prepolymers were obtained, on average, in 62% yield and were characterized by 13C NMR, 1H NMR, MALDI-TOF mass spectrometry, and GPC. The synthesized oligomer...

264

SYNTHESIS OF NEW MULTIFUNCTIONAL POLYOLS FROM AN OLEIC ACID DERIVATIVE  

Science.gov (United States)

Sophorolipids (SL) can be obtained in abundant yield from fermentation of inexpensive agricultural coproducts. Acid alcoholysis of SL removes the sugar portion to give 17- and 18-hydroxy fatty acid esters, usually stearate and oleate, essentially quantitatively. Linoleic products result when saffl...

265

EFFECT OF LEAD ON GAMMA AMINO BUTYRIC ACID SYNTHESIS  

Science.gov (United States)

The project studies the inhibitory effect of lead on the enzymatic activity of brain glutamic amino acid decarboxylase (GADC). The enzyme is responsible for the catalytic formation of gamma amino butyric acid (GABA) inhibitory neurons which is believed to be involved with the tra...

266

Synthesis of amino acids by arc-discharge experiments  

International Nuclear Information System (INIS)

Discharge was performed against ammonia water using a graphite rod as the anode and a silver thread as the cathode under an Ar atmosphere. HPLC and thin layer chromatograph (TLC) analyses showed that three kinds of amino acids were produced in the reaction mixture. As the graphite anode is the solitary source of carbon in the system, it is considered that amino acids have been produced by synthetic reaction between graphite and ammonia water. Thus, our results provide a possible way of formation of amino acids from elemental carbon on the primitive earth. In addition, the mechanism for the production of amino acids is discussed and the yields of different amino acids are presented

267

Inhibition of FASN reduces the synthesis of medium-chain fatty acids in goat mammary gland.  

Science.gov (United States)

Fatty acid synthase (FASN) is known as a crucial enzyme of cellular de novo fatty acid synthesis in mammary gland which has been proved as the main source of short and medium-chain fatty acids of milk. However, the regulatory role of FASN in goat-specific milk fatty acids composition remains unclear. We cloned and analyzed the full-length of FASN gene from the mammary gland of Capra hircus (Xinong Saanen dairy goat) (DQ 915966). Comparative gene expression analysis suggested that FASN is predominantly expressed in fat, small intestine and mammary gland tissues, and expresses higher level at lactation period. Inhibition of FASN activity by different concentrations (0, 5, 15, 25 and 35 ?M) of orlistat, a natural inhibitor of FASN, resulted in decreased expression of acetyl-CoA carboxylase ? (ACC?), lipoprotein lipase and heart-type fatty acid binding protein (H-FABP) in a concentration-dependent manner in goat mammary gland epithelial cells (GMEC). Similar results were also obtained by silencing of FASN. Additionally, reduction of FASN expression also led to apparent decline of the relative content of decanoic acid (C10:0) and lauric acid (C12:0) in GMEC. Our study provides a direct evidence for inhibition of FASN reduces cellular medium-chain fatty acids synthesis in GMEC. PMID:24909980

Zhu, J J; Luo, J; Wang, W; Yu, K; Wang, H B; Shi, H B; Sun, Y T; Lin, X Z; Li, J

2014-09-01

268

New synthesis of (11C)labeled fatty acid from H11CN  

International Nuclear Information System (INIS)

(11C)labeled palmitic acid has been used for the quantitative measurement of both regional myocardial perfusion and regional fatty acid metabolism with a PET imaging system. 3-Methyl-(1-11C)heptadecanoic acid, a fatty acid analog designed to inhibit the ?-oxidation process by preventing the formation of corresponding ?-ketoacyl SCoA has also been a useful myocardial metabolic tracer for PET. These (11C)labeled fatty acids have been synthesized by the use of the Grignard reaction. However this method has disadvantages such as the need for absolutely anhydrous solvent and the requirement for a lot of starting material (alkyl bromide). Therefore we proposed a new synthesis of (11C)labeled fatty acid by the use of H11CN which resulted in a better radiochemical yield and reproducibility. (author)

269

Novel hybrid DHPM-fatty acids: Synthesis and activity against glioma cell growth in vitro.  

Science.gov (United States)

We described the first synthesis of fatty acid 3,4-dihydropyrimidinones (DHPM-fatty acids) using the Biginelli multicomponent reaction. Antiproliferative activity on two glioma cell lines (C6 rat and U-138-MG human) was also reported. The novel DHPM-fatty acids reduced glioma cell viability relative to temozolomide. Hybrid oxo-monastrol-palmitic acid was the most potent, reducing U-138-MG human cell viability by ca. 50% at 10 ?M. In addition, the DHPM-fatty acids showed a large safety range to neural cells, represented by the organotypic hippocampal culture. These results suggest that the increased lipophilicity of DHPM-fatty acids offer a promising approach to overcoming resistance to chemotherapy and may play an important role in the development of new antitumor drugs. PMID:25863023

Treptow, Tamara G M; Figueiró, Fabrício; Jandrey, Elisa H F; Battastini, Ana M O; Salbego, Christianne G; Hoppe, Juliana B; Taborda, Priscila S; Rosa, Sabrina B; Piovesan, Luciana A; Montes D'Oca, Caroline Da R; Russowsky, Dennis; Montes D'Oca, Marcelo G

2015-05-01

270

Bispidine Derivatives : Synthesis and Interactions with Lewis Acids  

OpenAIRE

In this thesis, the improved synthesis and investigations into the properties of some 3,7-diazabicyclo[3.3.1]nonane (bispidine) derivatives are described. These compounds are structurally related to the naturally occurring lupanine alkaloids, they are of interest because of their cardiac antiarrhythmic function as well as their use as bases or ligands in organic chemical reactions. Their chemical properties are related to the presence of a rigid molecular scaffold with two nitrogen atoms that...

Toom, Lauri

2006-01-01

271

Synthesis of 5'-deoxy-5'-nucleosideacetic acid derivatives  

Science.gov (United States)

Several new 5'-deoxy-5'-nucleosideacetic acid derivatives have been synthesized by the reactions of alkoxycarbonylmethylene triphenylphosphoranes with nucleoside 5'-aldehydes. The oligomerization of adenine derivatives IIa, IIIa, IV, V and guanine derivatives IIc and IIIc in aqueous solution was studied using a water-soluble carbodiimide as a condensing agent. It is found that the saturated acid (IV) tends to cyclize to the lactone, while IIa and unsaturated acids (IIIa and V) oligomerized efficiently, especially in the presence of poly (U) as a template.

Harada, Kazuo; Orgel, Leslie E.

1990-01-01

272

Retinoic acid synthesis and functions in early embryonic development  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Retinoic acid (RA is a morphogen derived from retinol (vitamin A that plays important roles in cell growth, differentiation, and organogenesis. The production of RA from retinol requires two consecutive enzymatic reactions catalyzed by different sets of dehydrogenases. The retinol is first oxidized into retinal, which is then oxidized into RA. The RA interacts with retinoic acid receptor (RAR and retinoic acid X receptor (RXR which then regulate the target gene expression. In this review, we have discussed the metabolism of RA and the important components of RA signaling pathway, and highlighted current understanding of the functions of RA during early embryonic development.

Kam Richard Kin Ting

2012-03-01

273

A convenient synthesis of cis/trans-3-chloroacrylic acid-UL-14C  

International Nuclear Information System (INIS)

A convenient method for oxidation of allylic alcohols to the corresponding carboxylic acids is described. A two phase (methylene chloride/aqueous) silver oxide oxidation circumvents isolation of the intermediate aldehydes, thus making the procedure well suited to microscale carbon-14 synthesis. Although we required a mixture of cis/trans-3-chloro-acrylic acid-UL-14C and thus began the preparation with cis/trans-3-chloroallyl alcohol-UL-14C, the reaction sequence can be carried out starting with either isomer to provide the isomerically pure carboxylic acids. (author)

274

One pot, rapid and efficient synthesis of water dispersible gold nanoparticles using alpha-amino acids  

Science.gov (United States)

A detailed study on the synthesis of spherical and monodispersed gold nanoparticles (AuNPs) using all of the 20 naturally occurring ?-amino acids has been reported. The synthesized nanoparticles have been further characterized using various techniques such as absorbance spectroscopy, transmission electron microscopy, dynamic light scattering and nuclear magnetic resonance. Size control of the nanoparticles has been achieved by varying the ratio of the gold ion to the amino acid. These monodispersed water soluble AuNPs synthesized using non-toxic, naturally occurring ?-amino acids as reducing and capping/stabilizing agents serve as a remarkable example of green chemistry.

Wangoo, Nishima; Kaur, Sarabjit; Bajaj, Manish; Jain, D. V. S.; Sharma, Rohit K.

2014-10-01

275

Double-helical nucleic acids with cross-linked strands: synthesis and applications in molecular biology  

Energy Technology Data Exchange (ETDEWEB)

Data on the methods employed for cross-linking of DNA strands and for the synthesis of oligonucleotide duplexes with cross-links between strands are summarised. Existing methods are systematised; their advantages and drawbacks are discussed. The examples of applications of DNA duplexes with covalently cross-linked chains for the study of protein-nucleic acid recognition and mechanisms of action of nucleic acid-binding proteins for gaining information about the spatial structure of nucleic acids, and for the solution of other problems of molecular biology are given. The bibliography includes 131 references.

Antsypovitch, Sergei I; Oretskaya, Tat' yana S [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

1998-03-31

276

Synthesis and biological evaluation of novel pyrrolidine acid analogs as potent dual PPAR?/? agonists.  

Science.gov (United States)

The design, synthesis and structure-activity relationships of a novel series of 3,4-disubstituted pyrrolidine acid analogs as PPAR ligands is outlined. In both the 1,3- and 1,4-oxybenzyl pyrrolidine acid series, the preferred stereochemistry was shown to be the cis-3R,4S isomer, as exemplified by the potent dual PPAR?/? agonists 3k and 4i. The N-4-trifluoromethyl-pyrimidinyl pyrrolidine acid analog 4i was efficacious in lowering fasting glucose and triglyceride levels in diabetic db/db mice. PMID:25686852

Zhang, Hao; Ding, Charles Z; Lai, Zhi; Chen, Sean S; Devasthale, Pratik; Herpin, Tim; Morton, George; Qu, Fucheng; Ryono, Denis; Smirk, Rebecca; Wang, Wei; Wu, Shung; Ye, Xiang-Xang; Li, Yi-Xin; Apedo, Atsu; Farrelly, Dennis; Wang, Tao; Gu, Liqun; Morgan, Nathan; Flynn, Neil; Chu, Cuixia; Kunselman, Lori; Lippy, Jonathan; Locke, Kenneth; O'Malley, Kevin; Harrity, Thomas; Cap, Michael; Zhang, Lisa; Hosagrahara, Vinayak; Kadiyala, Pathanjali; Xu, Carrie; Doweyko, Arthur M; Zahler, Robert; Hariharan, Narayanan; Cheng, Peter T W

2015-03-15

277

Synthesis of 13C- and 14C-labeled methanesulfinic and methanesulfonic acids  

International Nuclear Information System (INIS)

The enzyme catalyzed displacement of the methyl sulfonyl group from pentachlorophenyl methyl sulfone, the m-chloroperoxybenzoic acid oxidation of methyl mercaptan and the reaction of methyllithium with sulfur dioxide and methods described for the synthesis of isotopically labeled methanesulfinic acid. The first two methods can be carried out on a milligram scale and are suitable for high specific activity preparations while the latter method is suitable for preparations on a gram scale. Conditions are also given for the preparation of isotopically labeled methanesulfonic acid. (author)

278

Synthesis of /sup 18/F-labeled 6- and 7-fluoropalmitic acids  

Energy Technology Data Exchange (ETDEWEB)

In order to investigate the uptake characteristics of palmitic (hexadecanoic) acid labeled with /sup 18/F at positions within the alkyl chain, (/sup 18/F)6- and 7-fluoropalmitates were synthesized. A precursor synthesis of several steps was followed by no-carrier-added (/sup 18/F) fluoride displacement of a methanesulfonate group and cleavage of the fatty acid benzyl ester. Preliminary myocardial uptake characteristics of the labeled compounds in rats were not markedly different from those of unsubstituted /sup 11/C labeled palmitic acid.

Berridge, M.S.; Tewson, T.J.; Welch, M.J. (Washington Univ., St. Louis, MO (USA). Edward Mallinckrodt Inst. of Radiology)

1983-04-01

279

De novo fatty acid synthesis controls the fate between regulatory T and T helper 17 cells.  

Science.gov (United States)

Interleukin-17 (IL-17)-secreting T cells of the T helper 17 (TH17) lineage play a pathogenic role in multiple inflammatory and autoimmune conditions and thus represent a highly attractive target for therapeutic intervention. We report that inhibition of acetyl-CoA carboxylase 1 (ACC1) restrains the formation of human and mouse TH17 cells and promotes the development of anti-inflammatory Foxp3(+) regulatory T (Treg) cells. We show that TH17 cells, but not Treg cells, depend on ACC1-mediated de novo fatty acid synthesis and the underlying glycolytic-lipogenic metabolic pathway for their development. Although TH17 cells use this pathway to produce phospholipids for cellular membranes, Treg cells readily take up exogenous fatty acids for this purpose. Notably, pharmacologic inhibition or T cell-specific deletion of ACC1 not only blocks de novo fatty acid synthesis but also interferes with the metabolic flux of glucose-derived carbon via glycolysis and the tricarboxylic acid cycle. In vivo, treatment with the ACC-specific inhibitor soraphen A or T cell-specific deletion of ACC1 in mice attenuates TH17 cell-mediated autoimmune disease. Our results indicate fundamental differences between TH17 cells and Treg cells regarding their dependency on ACC1-mediated de novo fatty acid synthesis, which might be exploited as a new strategy for metabolic immune modulation of TH17 cell-mediated inflammatory diseases. PMID:25282359

Berod, Luciana; Friedrich, Christin; Nandan, Amrita; Freitag, Jenny; Hagemann, Stefanie; Harmrolfs, Kirsten; Sandouk, Aline; Hesse, Christina; Castro, Carla N; Bähre, Heike; Tschirner, Sarah K; Gorinski, Nataliya; Gohmert, Melanie; Mayer, Christian T; Huehn, Jochen; Ponimaskin, Evgeni; Abraham, Wolf-Rainer; Müller, Rolf; Lochner, Matthias; Sparwasser, Tim

2014-11-01

280

Synthesis and characterisation of fatty acid bearing technetium complexes and their precursor stages  

International Nuclear Information System (INIS)

Over the past 25 years numerous research groups have studied the synthesis of 99mTc-coordinated fatty acids as a means of assessing the metabolic state of individual areas of the heart. Diverse chelate groups have been used for binding the radiometal to a fatty acid skeleton. As yet, however, the use of such 99mTc preparations in nuclear medicine has not been possible due to insufficient accumulation rates and poor substrate recognition during ? oxidation. The present study is therefore intended as a contribution to the study of new developments in technetium coordination chemistry and their suitability for the biocompatible marking of fatty acids. The focal areas of the present study were therefore as follows: synthesis and characterisation of ? functionalised fatty acid derivatives, which according to various coordination concepts should be suitable for binding to technetium; synthesis and structural characterisation of the relevant metal complexes using rhenium, an element similar to technetium in terms of its coordination chemistry which allows experimentation without radioactivity; and transfer of the coordination chemistry of the nonradioactive rhenium reference compound to the no-carrier-added 99mTc complex and provision of suitable 99mTc marked fatty acid preparations for a first assessment in the Langendorff perfused heart model

281

Stereocontrolled synthesis of syn-?-Hydroxy-?-amino acids by direct aldolization of pseudoephenamine glycinamide.  

Science.gov (United States)

?-Hydroxy-?-amino acids figure prominently as chiral building blocks in chemical synthesis and serve as precursors to numerous important medicines. Reported herein is a method for the synthesis of ?-hydroxy-?-amino acid derivatives by aldolization of pseudoephenamine glycinamide, which can be prepared from pseudoephenamine in a one-flask protocol. Enolization of (R,R)- or (S,S)-pseudoephenamine glycinamide with lithium hexamethyldisilazide in the presence of LiCl followed by addition of an aldehyde or ketone substrate affords aldol addition products that are stereochemically homologous with L- or D-threonine, respectively. These products, which are typically solids, can be obtained in stereoisomerically pure form in yields of 55-98?%, and are readily transformed into ?-hydroxy-?-amino acids by mild hydrolysis or into 2-amino-1,3-diols by reduction with sodium borohydride. This new chemistry greatly facilitates the construction of novel antibiotics of several different classes. PMID:24692320

Seiple, Ian B; Mercer, Jaron A M; Sussman, Robin J; Zhang, Ziyang; Myers, Andrew G

2014-04-25

282

Photosynthesis In Elodea canadensis Michx: Four-Carbon Acid Synthesis.  

Science.gov (United States)

Experiments to determine the early labeled photosynthetic products in Elodea canadensis show that after 2 seconds of exposure to NaH(14)CO(3), 45% of the (14)C incorporated is located in malate and aspartate. Phosphoglyceric acid and sugars account for 27% of the label during similar exposures. Equivalent amounts of organic acids and C(3) cycle products are present after 8 seconds. Four-carbon acids remain relatively unchanged throughout the first 45 seconds of exposure, while sugars increase in a linear fashion. Enzyme assays indicate that ribulose diphosphate and phosphoenolpyruvate carboxylase enzymes are present in a ratio of approximately 2:1. It appears that E. canadensis is able to synthesize significant amounts of four-carbon acids via beta-carboxylation and this may play a role in maintaining a pH favorable for carboxylation in aquatic plants. PMID:16660008

Degroote, D; Kennedy, R A

1977-06-01

283

New multifunctional phosphonic acid for metal phosphonate synthesis  

Science.gov (United States)

A new heterotopic phosphonic acid, 3-amino-5-(dihydroxyphosphoryl)benzoic acid (1) has been synthesized and obtained in the crystalline form. Second multifunctional phosphonic acid - namely 3-(dihydroxyphosphoryl)-5-nitrobenzoic acid (2) has also been obtained, following a different synthetic route than previously reported. Compound 1 crystallizes in a centrosymmetric space group of the triclinic system as monohydrate, sbnd C6H3(NH2)(COOH)PO3H2·H2O -1a. The molecule in the crystal exists in a zwitterionic form, in which one of the proton of the phosphonic group is transferred to the amine group. The zwitterionic molecules interact to each other and with water molecules via Nsbnd H…O and Osbnd H…O hydrogen bonds forming a three-dimensional network.

Garczarek, Piotr; Janczak, Jan; Zo?, Jerzy

2013-03-01

284

Synthesis and properties of acetylene esters of oil naphtenic acids  

International Nuclear Information System (INIS)

Full text: A number of new compound esters of acetylenic raw by etherification of oil naphtenic acids with acetylene alcohols and glycols in the presence of the catalyst of cat ion exchange resin KY-2 have been synthesized. It is shown that obtained acetylene esters easily enter into the reaction of hydrosillicylatig, aminoomethylating, of oxidizing, dimerization and hydration generating the new derivatives of oil naphtenic acids and may be applied as anticorrosive additives to motor oils

285

Biotransformation and Stereoselective Synthesis of Pharmaceutical Molecules from Linoleic Acid  

OpenAIRE

The biotransformation of linoleic acid 1 using immobilised soybean lipoxygenase in a dimethyl sulfoxide (DMSO) containing medium followed by sodium borohydride reduction afforded 13(S)-hydroxy-octadeca-9(Z),11(E)-dienoic acid 13(S)-HODE 2 in 69% yield. After methylation, methyl 13(S)-HODE was subjected to epoxidation using tert-butyl hydroperoxide (TBHP) in the presence of vanadyl acetylacetonate or titanium (IV) isopropoxide with D-(-)- or L-(+)-diisopropyl tartrate. Epoxidation catalysed by...

Muhammad Nor bin Omar; Nor, Nor Nazuha M.; Humphrey Moynihan; Richard Hamilton

2007-01-01

286

Biotin and Lipoic Acid: Synthesis, Attachment and Regulation  

OpenAIRE

Two vitamins, biotin and lipoic acid, are essential in all three domains of life. Both coenzymes function only when covalently attached to key metabolic enzymes. There they act as “swinging arms” that shuttle intermediates between two active sites (= covalent substrate channeling) of key metabolic enzymes. Although biotin was discovered over 100 years ago and lipoic acid 60 years ago, it was not known how either coenzyme is made until recently. In Escherichia coli the synthetic pathways f...

Cronan, John E.

2014-01-01

287

The synthesis and characterisation of some ortho-substituted phenoxyalkanoic acids and their derivatives  

Directory of Open Access Journals (Sweden)

Full Text Available The synthesis of 2-phenoxyalkanoic acids (ethanoic, propanoic, butanoic was realised by the reaction of ortho-hydroxybenzamide respectively N-phenyl-o-hydroxybenzamide with a-halogenated acids in aqueous sodium hydroxide solution. 2-[o-(carbamoylphenoxy]-2-methyl- and 2-[o-(phenylcarbamoylphenoxy]-2-methyl- propanoic acids were obtained by reaction of the appropriate amide with acetone, chloroform and sodium hydroxide. Ethyl esters of 2-phenoxyalkanoic acids were obtained by the reaction of the amide with ethyl esters of a-halogenated acids in different reaction media. Starting from the ethyl esters of 2-[2-(N-phenylcarbamoyl phenoxy]alkanoic acids with hydrazine 2-[2-(N-phenylcarbamoylphenoxy]alkanoic acids hydrazides were obtained, which are considered key intermediates for the synthesis of several series of new compounds. Schiff bases and N-imido-derivatives were obtained by condensation of hydrazide with substituted aromatic aldehydes respectively maleic anhydride. The synthesized compounds were characterized by physico-chemical methods (FTIR, NMR and mass spectrometry.

VALENTIN BADEA

2006-12-01

288

Synthesis of new fatty acids amides from aminolysis of fatty acid methyl esters (FAMEs); Sintese de novas amidas graxas a partir da aminolise de esteres metilicos  

Energy Technology Data Exchange (ETDEWEB)

Recent biochemical and pharmacological studies have led to the characterization of different fatty acid amides as a new family of biologically active lipids. Here, we describe the synthesis of new amides from C16:0, 18:0, 18:1 and 18:1, OH fatty acids (FFA) families with cyclic and acyclic amines and demonstrate for the first time that these compounds produce cytotoxic effects. Application of this method to the synthesis of fatty acid amides was performed using the esters aminolysis as a key step and various carboxylic amides were prepared in good yield from fatty acid methyl esters (FAMEs). (author)

Lopes, Carolina R.; Montes D' Oca, Caroline da Ros; Duarte, Rodrigo da C.; Kurz, Marcia H.S.; Primel, Ednei G.; Clementin, Rosilene M.; Villarreyes, Joaquin Ariel M.; Montes D' Oca, Marcelo G., E-mail: dqmdoca@furg.b [Universidade Federal do Rio Grande, RS (Brazil). Escola de Quimica e Alimentos

2010-07-01

289

Automated synthesis of 11C-acetoacetic acid, a key alternate brain fuel to glucose  

International Nuclear Information System (INIS)

An automated, one-pot radio-synthesis module for the routine preparation of 1-[11C]acetoacetic acid has been developed. The enolate anion of acetone was reacted with [11C]CO2 in tetrahydrofuran (THF), followed by hydrolysis and purification by ion-exchange chromatography. The total synthesis time was 18 min and radiochemical yield was 34% after decay correction. HPLC analysis showed ?3% impurities while residual THF (?200 ppm) and ethanol (?500 ppm) were well under the tolerable limits for human studies

290

Silver Colloid Synthesis in Linear and Branched Anionic Polymer Matrices by Using Ascorbic Acid as Reductant  

Directory of Open Access Journals (Sweden)

Full Text Available Silver colloids were synthesized in linear and branched anionic polymer matrices at different pH reducing by ascorbic acid. The template role of the host polymers in anionic form was studied at pH = 7 and pH = 12. Linear Polyacrylamide and star-like copolymers Dextran-graft-Polyacrylamide after alkaline hydrolysis were used as matrices. Silver colloids were studied by UV-Vis spectrophotometry just after synthesis and in 3 months. It is shown that branched polymer matrices are more efficient in comparison with linear one for in situ silver nanoparticle synthesis. The pH value affects the process of formation was investigated.

Korychenska O.

2013-09-01

291

Synthesis of dopamine analogue containing benzeneboronic acid group, a target compound for BNCT  

Energy Technology Data Exchange (ETDEWEB)

Melanin synthesis is accentuated in the melanoma cells. DOPA is one of the melanin precursors, and has been found to be the substrates for tyrosinase. Since Dopamine has the similar structure to DOPA, we have thought that the Dopamine containing boron atom has a possibility to be incorporated into the melanin synthesis pathway, resulting in both higher {sup 10}B-delivery and long lasting {sup 10}B-accumulation in melanoma. Thus, we tried to synthesize a new amide compound between Dopamine and p-carboxybenzeneboronic acid (PCBA). (author)

Mizuno, T.; Yoshino, K. [Shinshu Univ., Faculty of Science, Matsumoto, Nagano (Japan); Hiratsuka, J. [Kawasaki Medical School, Dept. of Radiation Oncology, Kurashiki, Okayama (Japan); Ichihashi, M. [Kobe Univ. (Japan). School of Medicine

2000-10-01

292

Synthesis of dopamine analogue containing benzeneboronic acid group, a target compound for BNCT  

International Nuclear Information System (INIS)

Melanin synthesis is accentuated in the melanoma cells. DOPA is one of the melanin precursors, and has been found to be the substrates for tyrosinase. Since Dopamine has the similar structure to DOPA, we have thought that the Dopamine containing boron atom has a possibility to be incorporated into the melanin synthesis pathway, resulting in both higher 10B-delivery and long lasting 10B-accumulation in melanoma. Thus, we tried to synthesize a new amide compound between Dopamine and p-carboxybenzeneboronic acid (PCBA). (author)

293

Synthesis and properties of radiation stabilized poly(?-amino acid)  

International Nuclear Information System (INIS)

In previous papers, one of the authors reported that modified poly(vinyl chloride) containing dithiocarbamate group has an excellent antiradiation property against ?-irradiation from the viewpoint of a negligibly small gaseous product, especially hydrogen chloride which was generated by radiolysis. Our studies of antiradiation polymers have now been extended to examine the stability of modified poly(?-amino acid) against ?-irradiation. Poly(?-amino acid) membranes have already been shown to be biologically compatible with blood and tissue. However, for practical uses of synthetic biomaterials, they would be required to be stable in the sterilization processing. The sterilization by ?-irradiation is more profitable for poly(?-amino acid) membranes which are less thermally stable. On the other hand, the transport of oxygen through poly(?-amino acid) membranes is of special interest because of the importance as a biomaterial for artificial lungs, skin and corneas. The purpose of the present study is to synthesize the antiradiation poly(?-amino acid) membranes by dithiocarbamate substitution, as well as to study the effect of dithiocarbamate substitution on the transport property of gases. (author)

294

Synthesis, purification and characterization of [3,5 D] p - aminobenzoic acid  

International Nuclear Information System (INIS)

This paper refers to the synthesis, purification and characterization of [3,5 D] p-aminobenzoic acid. The p-aminobenzoic acid is used in treatment of various rheumatoid arthrites and dermatological affections. The advantage of deuterium labelling of p-aminobenzoic acid is that some biomedical important aspects of collagen's behaviour are made clear. The introduction of deuterium in the p-aminobenzoic acid molecule is done on in this way: - The bromination with elementary bromine into 3 and 5 positions of p-aminobenzoic acid; - The replacement of bromine with deuterium through catalytic debromination reaction. The purification has been carried out through the selective extraction and the characterization of the product has been carried out through Nuclear Magnetic Resonance and other physico-chemical methods. (authors)

295

Synthesis of starch-g-lactic acid copolymer with high grafting degree catalyzed by ammonia water.  

Science.gov (United States)

The study of starch-g-lactic acid copolymer has gained much attention for its completely degradable property, but its intricate synthetic procedure and low graft degree inhibited its further application. In this work, the synthesis of starch-g-lactic acid copolymer was attempted via the catalysis of ammonia water by one-step process, and the structure of starch-g-lactic acid copolymer was characterized by means of IR, (13)C NMR and HMBC. The synthetic conditions were optimized as follows, the starch was activated for 2h at 80°C at first, starch and lactic acid with weight ratios of 1:4 reacted for 4h at 90°C in vacuum. The starch-g-lactic acid copolymer can be finally obtained with graft degree of starch 58.9%. PMID:25542110

Hu, Yingmo; Tang, Mingru

2015-03-15

296

Convergent synthesis of degradable dendrons based on L-malic acid  

DEFF Research Database (Denmark)

New degradable polyester dendrons based on the cellular tricarboxylic acid cycle component L-malic acid were synthesized up to the third generation by convergent synthesis. The dendron wedges could be introduced in a stepwise, highly regioselective fashion. HMBC-NMR revealed that the C1-carbonyl on malic acid was exclusively esterified, before the reaction of the second dendron wedge at C4 took place. Degradation studies on a first generation dendron analyzed by HPLC showed that hydrolytic degradation of the dendron most profoundly takes place at pH 4 and pH 9 with the highest degradation rate at alkaline pH. NMR shows that the dendron degrades to malic acid and fumaric acid derivatives. Preliminary studies performed in the cell culture show low toxicity of the dendrons in concentrations of up to 50 ?g mL-1.

Meyhoff, Ulrich; Riber, Ulla

2015-01-01

297

Thermal synthesis of amino acids and the origin of life  

Science.gov (United States)

The recent review by Marshall (1994) of the production of amino acids from the interstellar components, formaldehyde and ammonia, is placed in the larger context of the origin of life. Thermal energy, being ubiquitous in the Earth, emerges as the sole necessary form of energy. To appreciate the overview of the natural evolutionary sequence it is necessary to recognize stepwiseness in evolution, a principle that has however been often ignored. Since self organization of thermal protein to cells is instantaneous, but only one step in a geochemical ladder, individual steps may be regarded as instantaneous, while the sequence requires measurable time. Two steps indicated are extrusion of a hot, dry organic magma of amino acids ? peptides into an aqueous environment in which occurs a second step of self organization. In this paper, spinoffs of the defensible theory for the origin of life have been briefly reviewed as a fundamental consequence of nonrandom thermal copolymerization of amino acids.

Fox, Sidney W.

1995-03-01

298

Synthesis and anticancer activity of quinopimaric and maleopimaric acids’ derivatives.  

Science.gov (United States)

A series of quinopimaric and maleopimaric acids’ derivatives modified in the E-ring, at the carbonyl- and carboxyl-groups were synthesized and their in vitro cytotoxic activity was evaluated at the National Cancer Institute, USA. Methyl esters of dihydroquinopimaric, 1a,4a-dehydroquinopimaric, 2,3-epoxyquinopimaric, 1-ethylenketal-dihydroquinopimaric, 1-ethylenketal-4-hydroxyiminodihydroquinopimaric acids displayed an activity on renal cancer, leukemia, colon cancer and breast cancer cell lines in concentration 10(?5) M. Methyl 1,4-dihydroxyiminodihydroquinopimarate showed both a potent and broad spectrum of cytotoxic activity against NSC lung cancer, colon cancer, breast cancer, renal cancer and leukemia and revealed in vivo antineoplastic activity towards mouse solid transplantable mammary carcinoma Ca755 and colon adenocarcinoma AKATOL. The information about antineoplastic activity of the studied quinopimaric and maleopimaric acids’ derivatives will be used for hit to lead optimization in these chemical series. PMID:25440729

Tretyakova, Elena V; Smirnova, Irina E; Kazakova, Oxana B; Tolstikov, Genrikh A; Yavorskaya, Nadejda P; Golubeva, Irina S; Pugacheva, Rujena B; Apryshko, Galina N; Poroikov, Vladimir V

2014-11-15

299

Synthesis of potential Schistosomicides: new 2-(alkylamino)-1-octometiosulfuric acids  

International Nuclear Information System (INIS)

Four new 2-(alkylamino)-1-octanethiosulfuric acids (1) were synthesized from 1-octene. 1-Octene was epoxidized with MCPBA or with a two-phase system composed of H2O2, sodium tungstate, phosphoric acid, 1-octene and a phase transfer agent. Reaction of the 1,2-epoxyoetane with primary amines furnished 1-(alkylamino)-2octanols which were converted to the respective N-alkyl-2-bromo-1-octanamine hydrobromides by reaction with hydrobromic acid, followed by phosphorus tribromide. Finally, substitution of the bromide ion with sodium thiosulfate was accompanied by rearrangement via an aziridine intermediate, resulting in formation of the product. 1. The intermediates and the final products were screened for activity against infection by Schistosoma mansoni, only the final products in which the N-alkyl group was sec-butyl or isopropyl exhibited activity. Nuclear magnetic resonance and infrared and mass spectroscopy analysis are presented. (author)

300

Radiation synthesis and characterization of polyacrylic acid hydrogels  

International Nuclear Information System (INIS)

The pH-sensitive polyacrylic acid (PAA) hydrogels were synthesized by gamma-ray irradiation at an ambient temperature. The influences of dose, monomer concentration, cross-linking agent content, pH, and ionic strength on the swelling ratio (SR) of the PAA hydrogels were investigated in detail. The results show that the SR of the hydrogel decreases with an increase in the dose, monomer concentration, and cross-linking agent content. In alkaline solution, the SR of the hydrogels is much higher than that in acid solution. Also, the ionic strength can influence the SR of the hydrogels. The more the concentration, the lower the SR. (authors)

301

Synthesis and in vitro Cytotoxicity of Novel Ursolic Acid Derivatives  

Directory of Open Access Journals (Sweden)

Full Text Available In an effort to improve potential hepatoprotective and anti-tumor activities, eight novel ursolic acid (UA derivatives were designed and synthesized with substitution at positions of C-3, C-11and C-28 of UA. Their structures were confirmed using IR, MS and 1H-NMR and elemental analysis. Their in vitro cytotoxicity against various cancer cell lines (HeLa, SKOV3 and BGC-823 was evaluated by the standard MTT assay. Among them, compound 13 exhibited more potent cytotoxicity than ursolic acid.

Yanqiu Meng

2010-06-01

302

Synthesis, characterization and analytical application of a hydroxamic acid resin.  

Science.gov (United States)

A chelating ion-exchange resin with hydroxamic acid functional groups was synthesized from styrene-maleic acid co-polymer cross-linked with divinylbenzene. A resin prepared from equimolar amounts of styrene and maleic anhydride with 0.75 mole% divinylbenzene gives the best sorption characteristics. The selectivity of the resin for metal ions is copper(II) > cobalt(II) > zinc(II) > nickel(II) > manganese(II) > chromium(III) > iron(III) > vanadium(V). Copper(II), chromium(III) and iron(III) in chromium plating baths can be separated by use of the resin and determined spectrophotometrically. PMID:18964984

Mendez, R; Pillai, V N

1990-06-01

303

SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF OXIME ESTERS FROM DIHYDROCUMIC ACID  

Directory of Open Access Journals (Sweden)

Full Text Available Dihydrocumic acid was prepared from ?-pinene through oxidation and dehydration. Then, ten oxime esters from dihydrocumic acid were synthesized. Reaction conditions of the oxime esters were adjusted and their structures were characterized by IR, 1H-NMR, MS, and elemental analysis. The antibacterial activity of these newly synthesized oxime esters against Gram-negative bacteria and Gram-positive bacteria was also investigated using the inhibition zone method. The preliminary results indicated that seven compounds displayed better antibacterial activity against Gram-negative bacteria compared with bromogeramine, a commercially available antibacterial agent.

Yanqing Gao,

2012-07-01

304

High-yield, enzymatic synthesis of 14C- or 3H-labeled 1-O-valproyl-?-D-glucopyranuronic acid, the main metabolite of valproic acid in human  

International Nuclear Information System (INIS)

A simple and high yield synthesis of radiolabeled 1-O-valproyl-?-D-glucopyranuronic acid was developed with the use of UDP-glucuronosyltransferase. Valproic acid, UDP-glucuronic acid, and UDP-glucuronosyltransferase were incubated for 48 h at an optimum pH of 8.5. The enzymatic synthesis followed by column purification gave 51.8% and 52.5% yields of 14C- and 3H- labeled 1-O-valproyl-?-D-glucopyranuronic acid, respectively. The radiochemical purities of the 14C- and 3H-labeled substances were 98.8% and 99.2%, respectively. In contrast, the chemical synthesis using 2,3,4,6-tetrabenzyl-D-glucopyranose and valproic acid resulted in much lower yield (6.8%). (author)

305

A C2-symmetric chiral pool-based flexible strategy: synthesis of (+)- and (-)-shikimic acids, (+)- and (-)-4-epi-shikimic acids, and (+)- and (-)-pinitol.  

Science.gov (United States)

Via combination of a novel acid-promoted rearrangement of acetal functionality with the controlled installation of the epoxide unit to create the pivotal epoxide intermediates in enantiomerically pure form, a simple, concise, flexible, and readily scalable enantiodivergent synthesis of (+)- and (-)-shikimic acids and (+)- and (-)-4-epi-shikimic acids has emerged. This simple strategy not only provides an efficient approach to shikimic acids but also can readily be adopted for the synthesis of (+)- and (-)-pinitols. These concise total syntheses exemplify the use of pivotal allylic epoxide 14 and its enantiomer ent-14. A readily available inexpensive C2-symmetric L-tartaric acid (7) served as key precursor. In general, the strategy here provides a neat example of the use of a four-carbon chiron and offers a good account of the synthesis of functionalized cyclohexane targets. PMID:24617456

Ananthan, Bakthavachalam; Chang, Wan-Chun; Lin, Jhe-Sain; Li, Pin-Hui; Yan, Tu-Hsin

2014-04-01

306

Highly Stereoselective Brønsted Acid-Catalyzed Synthesis of Spirooxindole Pyrans  

Science.gov (United States)

A Brønsted acid-catalyzed Prins-type cyclization sequence to construct spirooxindole pyrans in high yields and excellent diastereoselectivity has been developed. The combination of a ?-hydroxy dioxinone fragment and isatin dimethyl acetal generate oxa-spirooxindoles efficiently. These compounds are diversifiable scaffolds that tap into the rich chemistry of dioxinones. PMID:21591768

Wang, Jingqi; Crane, Erika A.

2011-01-01

307

Highly stereoselective Brønsted acid catalyzed synthesis of spirooxindole pyrans.  

Science.gov (United States)

A Brønsted acid-catalyzed Prins-type cyclization sequence to construct spirooxindole pyrans in high yields and excellent diastereoselectivity has been developed. The combination of a ?-hydroxy dioxinone fragment and isatin dimethyl acetal generate oxa-spirooxindoles efficiently. These compounds are diversifiable scaffolds that tap into the rich chemistry of dioxinones. PMID:21591768

Wang, Jingqi; Crane, Erika A; Scheidt, Karl A

2011-06-17

308

Synthesis of [1,2-C-14]trichloroacetic acid.  

Czech Academy of Sciences Publication Activity Database

Ro?. 44, ?. 11 (2001), s. 811-814. ISSN 0362-4803 R&D Projects: GA ?R GA522/99/1465 Institutional research plan: CEZ:AV0Z5038910 Keywords : [1,2-C-14]trichloroacetic acid Subject RIV: CE - Biochemistry Impact factor: 0.839, year: 2001

Bubner, M.; Fuksová, K.; Matucha, Miroslav; Heise, K.; Bernhard, G.

2001-01-01

309

The use of poly(ethylene terephthalate)-poly(aniline) composite for trypsin immobilisation  

Energy Technology Data Exchange (ETDEWEB)

This paper presents trypsin immobilisation on strips of poly(ethylene terephthalate)-poly(aniline), activated with glutaraldehyde (PET-PANIG) composite. The photomicrography of the material showed changes corresponding to the chemical modifications produced in the steps of synthesis. The immobilisation process was very efficient under optimal conditions (18.6%). The immobilised and free enzyme presented the same pH and temperature optimum. PET-PANIG-trypsin was able to hydrolyse casein, albumin, gelatine, and skimmed milk. Km{sub app} value for PET-PANIG-trypsin was very close to Km of the free enzyme for casein. Immobilised trypsin showed higher stability than the free enzyme, with 100% activity after 14 days of storage at 4 deg. C and 100% operational stability after 4 cycles of use.

Caramori, S.S. [Laboratorio de Quimica de Proteinas, Departamento de Bioquimica e Biologia Molecular, Instituto de Ciencias Biologicas, Universidade Federal de Goias, Cx. Postal 131, 74001-970 Goiania-GO (Brazil)], E-mail: samanthabio@hotmail.com; Fernandes, K.F. [Laboratorio de Quimica de Proteinas, Departamento de Bioquimica e Biologia Molecular, Instituto de Ciencias Biologicas, Universidade Federal de Goias, Cx. Postal 131, 74001-970 Goiania-GO (Brazil)], E-mail: katia@icb.ufg.br

2008-08-01

310

The use of poly(ethylene terephthalate)-poly(aniline) composite for trypsin immobilisation  

International Nuclear Information System (INIS)

This paper presents trypsin immobilisation on strips of poly(ethylene terephthalate)-poly(aniline), activated with glutaraldehyde (PET-PANIG) composite. The photomicrography of the material showed changes corresponding to the chemical modifications produced in the steps of synthesis. The immobilisation process was very efficient under optimal conditions (18.6%). The immobilised and free enzyme presented the same pH and temperature optimum. PET-PANIG-trypsin was able to hydrolyse casein, albumin, gelatine, and skimmed milk. Kmapp value for PET-PANIG-trypsin was very close to Km of the free enzyme for casein. Immobilised trypsin showed higher stability than the free enzyme, with 100% activity after 14 days of storage at 4 deg. C and 100% operational stability after 4 cycles of use

311

The solubilities of benzene polycarboxylic acids in water  

International Nuclear Information System (INIS)

The solubilities in water of all benzene polycarboxylic acids are discussed, using data determined in this work (benzoic, terephthalic, trimellitic, trimesic, and pyromellitic acids) and available from the literature (benzoic, phthalic, isophthalic, terephthalic, hemimellitic, trimelitic, trimesic, mellophanic, prehnitic, pyromellitic, benzene-pentacarboxylic and mellitic acids). The apparent molar enthalpies of solution at the saturation point for these benzene polycarboxylic acids were determined from the temperature dependence of the solubilities

312

The solubilities of benzene polycarboxylic acids in water  

Energy Technology Data Exchange (ETDEWEB)

The solubilities in water of all benzene polycarboxylic acids are discussed, using data determined in this work (benzoic, terephthalic, trimellitic, trimesic, and pyromellitic acids) and available from the literature (benzoic, phthalic, isophthalic, terephthalic, hemimellitic, trimelitic, trimesic, mellophanic, prehnitic, pyromellitic, benzene-pentacarboxylic and mellitic acids). The apparent molar enthalpies of solution at the saturation point for these benzene polycarboxylic acids were determined from the temperature dependence of the solubilities.

Apelblat, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel)]. E-mail: apelblat@bgu.ac.il; Manzurola, Emanuel [Department of Chemical Engineering, Ben Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel); Abo Balal, Nazmia [Negev Academic College of Engineering, Beer Sheva (Israel)

2006-05-15

313

Polyaniline-dodecylhydrogensulfate-acid salt: synthesis and characterization  

International Nuclear Information System (INIS)

Polyaniline salts such as polyaniline-dodecylhydrogensulfate-sulfuric acid (PANI-DHS-H2SO4), polyaniline-dodecylhydrogensulfate-nitric acid (PANI-DHS-HNO3) and polyaniline-dodecylhydrogensulfate-hydrochloric acid salt (PANI-DHS-HCl) in chloroform were synthesized by chemical oxidative polymerization of aniline using pyridinium chloro chromate (PCC) as an oxidizing agent in aqueous-organic medium in presence of mineral acid and sodiumdodecylsulfate (SDS) surfactant. This process is being reported for the first time. PANI-DHS-H2SO4 was also synthesized in different organic solvents such as benzene, xylene and toluene. This polymerization pathway leads to incorporation of both acid and surfactant groups into the polyaniline chain as dopants. Incorporation of SDS surfactant in to the polyaniline chain solubilizes the polyaniline salt in organic solvents. In this polymerization SDS plays a dual role as efficient surfactant and as dopant. Polyaniline in the powder form was recovered by adding acetone to the organic solvent containing polyaniline salt. The polyaniline samples were characterized by Fourier transform-infrared, electronic absorption, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and conductivity measurements. The yield of PANI-DHS-H2SO4, PANI-DHS-HNO3 and PANI-DHS-HCl in chloroform solvent was 1.25g, 1.15g and 1.20g, respectively. However5g, 1.15g and 1.20g, respectively. However, the conductivity of PANI-DHS-H2SO4 was found to be high (0.1Scm-1) when compared to PANI-DHS-HNO3 (0.07Scm-1) and PANI-DHS-HCl (0.04Scm-1). The conductivity (0.1-0.2Scm-1) and yield (1.20-1.25g) of PANI-DHS-H2SO4 salts prepared using different solvents were almost the same

314

Improved conventional synthesis for 14C-labeled polyglutamates of folic acid  

International Nuclear Information System (INIS)

The majority of folates existing in nature are of the pteroylpolyglutamyl form and are unable to support Lactobacillus casei growth until the ?-linked glutamyls are digested by conjugase enzymes. Most studies involving folate absorption have utilized monoglutamyl forms of folate, primarily folic acid. Synthetic pteroylpolyglutamates prepared by solid phase or conventional synthesis provided conjugated materials with which to study the absorption and metabolism of natural derivatives; however, the synthetic hepataglutamates support microbiological growth prior to enzymatic hydrolysis whereas the natural conjugates do not. Incomplete purification of intermediate peptides during the synthesis would be the most likely explanation of this growth phenomenon. A modified solution synthesis has been developed which improves upon intermediate peptide condensations, increases product yields, and provides a heptapeptide which does not support microbiological growth until after enzymatic hydrolysis. (author)

315

Effects of Long Chain Fatty Acid Synthesis and Associated Gene Expression in Microalga Tetraselmis sp.  

Directory of Open Access Journals (Sweden)

Full Text Available With the depletion of global fish stocks, caused by high demand and effective fishing techniques, alternative sources for long chain omega-3 fatty acids are required for human nutrition and aquaculture feeds. Recent research has focused on land-based cultivation of microalgae, the primary producers of omega-3 fatty acids in the marine food web. The effect of salinity on fatty acids and related gene expression was studied in the model marine microalga, Tetraselmis sp. M8. Correlations were found for specific fatty acid biosynthesis and gene expression according to salinity and the growth phase. Low salinity was found to increase the conversion of C18:4 stearidonic acid (SDA to C20:4 eicosatetraenoic acid (ETA, correlating with increased transcript abundance of the ?-6-elongase-encoding gene in salinities of 5 and 10 ppt compared to higher salinity levels. The expression of the gene encoding ?-ketoacyl-coenzyme was also found to increase at lower salinities during the nutrient deprivation phase (Day 4, but decreased with further nutrient stress. Nutrient deprivation also triggered fatty acids synthesis at all salinities, and C20:5 eicosapentaenoic acid (EPA increased relative to total fatty acids, with nutrient starvation achieving a maximum of 7% EPA at Day 6 at a salinity of 40 ppt.

T. Catalina Adarme-Vega

2014-06-01

316

Synthesis and Screening of New Enantiomeracally Enriched Non-Protein (S) and (R)-? -Amino Acids, Peptides and Polymers  

International Science & Technology Center (ISTC)

Synthesis and Screening of New Potentially Pharmacologically Active Enantiomerically Enriched Non-Protein (S) and (R)-? -Amino Acids, Peptides and Polymers Containing Acetylenic Groups in the Side-Chain Radical

317

Association of plasma insulin concentration to fatty acid distribution between milk fat and membrane synthesis.  

Science.gov (United States)

We examined the association between plasma insulin concentration and fatty acid distribution to milk fat and membrane fractions (triglyceride and phospholipid, respectively) in dairy cows. Thirty-seven Holstein cows at 60 to 70 d postpartum were synchronized by 2 PGF(2?) injections 14 d apart. Plasma samples were taken before morning and evening milkings and milk samples were obtained at morning milking. Plasma insulin concentrations were determined and cows were retrospectively assigned to low insulin (LI; 2.8±0.2 ng/mL, n=6) or high insulin (HI; 5.9±0.6 ng/mL, n=7) experimental groups. Fatty acid analysis of milk samples demonstrated a possible association between plasma insulin concentration and the fatty acid composition in phospholipid and triglyceride fractions. In the HI group, monounsaturated fatty acid concentration tended to be higher in the triglyceride (Tg) fraction than the phospholipids (Pl) fraction. In the LI group, the concentrations of short- and medium-chain saturated fatty acids (triglyceride fraction than the phospholipid fraction. These results imply that the primary source of saturated fatty acids for phospholipid synthesis, in both HI and LI groups, is the circulation, as reflected by a higher concentration of longer saturated fatty acids (>16 carbon chain length) in the phospholipid fraction. Finally, the phospholipid-to-triglyceride ratio was higher in the HI group than in the LI group. Together, the results indicate that fatty acid distribution between phospholipid (membrane) and triglyceride (fat) synthesis by the mammary gland is associated with fatty acid length, degree of unsaturation, and origin, and might be subject to metabolic hormone regulation. Furthermore, a lower triglyceride-to-phospholipid ratio in the HI group implies that high plasma insulin and low milk fat concentrations are associated with a shift in the size distribution of milk fat globules. PMID:22459825

Mesilati-Stahy, R; Malka, H; Argov-Argaman, N

2012-04-01

318

Synthesis of fluorescent D-amino acids and their use for probing peptidoglycan synthesis and bacterial growth in situ.  

Science.gov (United States)

Fluorescent D-amino acids (FDAAs) are efficiently incorporated into the peptidoglycans (PGs) of diverse bacterial species at the sites of PG biosynthesis, allowing specific and covalent probing of bacterial growth with minimal perturbation. Here we provide a protocol for the synthesis of four FDAAs emitting light in blue (HCC-amino-D-alanine, HADA), green (NBD-amino-D-alanine, NADA, and fluorescein-D-lysine, FDL) or red (TAMRA-D-lysine, TDL) and for their use in PG labeling of live bacteria. Our modular synthesis protocol gives easy access to a library of different FDAAs made with commercially available fluorophores and diamino acid starting materials. Molecules can be synthesized in a typical chemistry laboratory in 2-3 d using standard chemical transformations. The simple labeling procedure involves the addition of the FDAAs to a bacterial sample for the desired labeling duration and stopping further label incorporation by fixing the cells with cold 70% (vol/vol) ethanol or by washing away excess dye. We discuss several scenarios for the use of these labels in fluorescence microscopy applications, including short or long labeling durations, and the combination of different labels in pure culture (e.g., for 'virtual time-lapse' microscopy) or in situ labeling of complex environmental samples. Depending on the experiment, FDAA labeling can take as little as 30 s for a rapidly growing species such as Escherichia coli. PMID:25474031

Kuru, Erkin; Tekkam, Srinivas; Hall, Edward; Brun, Yves V; Van Nieuwenhze, Michael S

2015-01-01

319

Synthesis of a nano-crystalline solid acid catalyst from fly ash and its catalytic performance  

Energy Technology Data Exchange (ETDEWEB)

The synthesis of nano-crystalline activated fly ash catalyst (AFAC) with crystallite size of 12 nm was carried out by chemical and thermal treatment of fly ash, a waste material generated from coal-burning power plants. Fly ash was chemically activated using sulfuric acid followed by thermal activation at 600{sup o}C. The variation of surface and physico-chemical properties of the fly ash by activation methods resulted in improved acidity and therefore, catalytic activity for acid catalyzed reactions. The AFAC was characterized by X-ray diffraction, FT-IR spectroscopy, N{sub 2}-adsorption-desorption isotherm, scanning electron microscopy, flame atomic absorption spectrophotometry and sulfur content by CHNS/O elemental analysis. It showed amorphous nature due to high silica content (81%) and possessed high BET surface area (120 m{sup 2}/g). The catalyst was found to be highly active solid acid catalyst for liquid phase esterification of salicylic acid with acetic anhydride and methanol giving acetylsalicylic acid and methyl salicylate respectively. A maximum yield of 97% with high purity of acetylsalicylic acid (aspirin) and a very high conversion 87% of salicylic acid to methyl salicylate (oil of wintergreen) was obtained with AFAC. The surface acidity and therefore, catalytic activity in AFAC was originated by increased silica content, hydroxyl content and higher surface area as compared to fly ash. The study shows that coal generated fly ash can be converted into potential solid acid catalyst for acid catalyzed reactions. Furthermore, this catalyst may replace conventional environmentally hazardous homogeneous liquid acids making an ecofriendly; solvent free, atom efficient, solid acid based catalytic process. 27 refs., 5 figs., 2 tabs.

Chitralekha Khatri; Ashu Rani [Government P.G. College, Kota (India). Environmental Chemistry Laboratory

2008-10-15

320

Synthesis and characterization of the hexenuronic acid model methyl 4-deoxy-beta-L-threo-hex-4-enopyranosiduronic acid.  

Science.gov (United States)

A facile synthetic scheme for the preparation of methyl 4-deoxy-beta-L-threo-hex-4-enopyranosiduronic acid utilizing the commercially available methyl alpha-D-galactopyranoside as starting material has been developed. The synthesis sequence comprises six high yielding reaction steps: TEMPO oxidation, acetylation, methanolysis of the lactone, acetylation, beta-elimination, and final removal of the protecting groups. Only one column chromatographic purification is needed throughout the whole sequence. The overall yield is 60%. The final product has been characterized by NMR, Raman, UVRR, FTIR, and HRMS. PMID:16876146

Adorjan, Immanuel; Jääskeläinen, Anna-Stiina; Vuorinen, Tapani

2006-10-16

321

First synthesis of thia steroids from cholic acid.  

Science.gov (United States)

Heterosteroids remain interesting due to their potential biological activities. This prompted us to synthesize novel thia steroids possessing the heteroatom in the A-ring. We set out to describe a new and versatile method for preparing 3-thia steroids from cholic acid via a selective oxidation of one hydroxyl group, a Baeyer-Villiger oxidation and a photolysis as the key steps. The characteristic (1)H and (13)C NMR spectroscopic features of the synthesized compounds are reported. PMID:20435053

Ibrahim-Ouali, Malika; Rocheblave, Luc

2010-10-01

322

Synthesis and curing of alkyd enamels based on ricinoleic acid  

OpenAIRE

A combination of an alkyd resin with a melamine-formaldehyde resin gives a cured enamel film with the flexibility of the alkyd constituent and the high chemical resistance and hardness of the melamine resin at the same time. The melamine resin is a minor constituent and plays the role of a crosslinking agent. In this paper, alkyd resins of high hydroxyl numbers based on trimethylolpropane, ricinoleic acid and phthalic anhydride were synthesized. Two alkyds having 30 and 40 wt% of ricino...

Jovi?i? Mirjana C.; Z?, Radic?evic? Radmila; Simendi? Vesna B.

2010-01-01

323

Liquid-Phase Synthesis of Cyanuric Acid from Urea  

OpenAIRE

The focus of this paper was to identify a cheaper solvent from among diesel fuel, kerosene, sulfolane or a mixture of sulfolane and cyclohexanol for the preparation of cyanuric acid heterocyclization of urea. To obtain a higher yield, the effects of catalyst (sodium, ammonium, calcium and zinc salts) and temperature (160 °C to 220 °C) on the trimerization of urea were also carefully studied. We established the optimal reaction conditions and further validated them in our scale-up experiments.

Fen-Ming Li; Chun-Jiu Li; Qi-Liang Huang; Hai-Lin Yu; Dong-Mei She

2010-01-01

324

Synthesis and aromatisation of cyclic enediyne-containing amino acids.  

Science.gov (United States)

A series of cyclic enediyne-containing amino acids with ring sizes varying from 10 to 12 atoms have been prepared starting from propargylglycine and homopropargylglycine. Their reactivity towards Bergman cyclisation under elevated temperatures has been explored. The enediynes displayed marked differences in cyclisation half-lives depending on the olefinic substituent and the ring size. A potential candidate for incorporation into peptides has been identified. PMID:19194585

Kaiser, Jasper; van Esseveldt, Bart C J; Segers, Margot J A; van Delft, Floris L; Smits, Jan M M; Butterworth, Sam; Rutjes, Floris P J T

2009-02-21

325

Evolution of Abscisic Acid Synthesis and Signaling Mechanisms  

OpenAIRE

The plant hormone abscisic acid (ABA) mediates seed dormancy, controls seedling development and triggers tolerance to abiotic stresses, including drought. Core ABA signaling components consist of a recently identified group of ABA receptor proteins of the PYRABACTIN RESISTANCE (PYR)/REGULATORY COMPONENT OF ABA RECEPTOR (RCAR) family that act as negative regulators of members of the PROTEIN PHOSPHATASE 2C (PP2C) family. Inhibition of PP2C activity enables activation of SNF1-RELATED KINASE 2 (S...

Hauser, Felix; Waadt, Rainer; Schroeder, Julian I.

2011-01-01

326

Synthesis of cyclic hydroxamic acids through -NOH insertion of ketones.  

Science.gov (United States)

Treatment of cyclobutanone or cyclopentanone with N-hydroxybenzenesulfonamide under basic conditions yields the ring-expanded cyclic hydroxamic acid in 18-69% yield. Reactions of substituted cyclobutanones give ring expanded products where the -NOH group regio- and stereoselectively inserts to the more substituted position. This expansion likely proceeds through a mechanism that includes addition of the N-anion of N-hydroxybenzenesulfonamide to the ketone and a C-nitroso intermediate that rearranges to the final product. PMID:19743817

Banerjee, Ranjan; King, S Bruce

2009-10-15

327

Synthesis, Preliminary Bioevaluation and Computational Analysis of Caffeic Acid Analogues  

OpenAIRE

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

Zhiqian Liu; Jianjun Fu; Lei Shan; Qingyan Sun; Weidong Zhang

2014-01-01

328

Synthesis and characterization of deoxyribonucleic acid-conjugated gold nanoparticles.  

Science.gov (United States)

Gold nanoparticles functionalized with thiol-modified single-stranded oligonucleotides are highly useful reagents for a variety of applications, ranging from materials science to bioanalytics. In this chapter, the preparation of citrate stabilized 15-nm Au nanoparticles is described. The nanoparticles are conjugated with 3'-thiol-modified deoxyribonucleic acid oligomers and the resulting conjugates are characterized by determining their shape, size, and surface coverage. The hybridization capabilities are quantified in a microplate assay. PMID:15197320

Hazarika, Pompi; Giorgi, Tatiana; Reibner, Martina; Ceyhan, Buelent; Niemeyer, Christof M

2004-01-01

329

New and Efficient Synthesis of Amides from Acid Chlorides Using Diisobutyl(amino)aluminum  

International Nuclear Information System (INIS)

In conclusion, we have developed a facile, alternative method for the formation of secondary and tertiary amides including morpholine amides from acid chlorides by using diisobutyl(amino)aluminum under mild reaction conditions. The advantages of the present method include the high product yields, simple experimental procedure, short reaction time (10 min), and the fact that an excess amount of amine is not required. This result suggests that our new method can provide an alternative method for the synthesis of useful amides from acid chlorides. Amides are valuable functional groups in biological, agrochemical, and pharmaceutical molecules. Several amides such as Weinreb amides, morpholine amides, and pyrrolidine amides are useful intermediates for the synthesis of aldehydes or ketones. Among them, morpholine amides are a cheap and good substitute for Weinreb amides

330

Continuous-flow reactor-based synthesis of carbohydrate and dihydrolipoic acid-capped quantum dots.  

Science.gov (United States)

A detailed protocol for the large-scale synthesis of carbohydrate and dihydrolipoic acid (DHLA)-coated CdSe/ZnS and CdTe/ZnS nanoparticles using continuous flow reactors is described here. Three continuous flow microreaction systems, operating at three different temperatures, are used for the synthesis of mannose-, galactose- or DHLA-functionalized quantum dots (QDs). In the first step of synthesis, the CdSe and CdTe nanoparticles are prepared. The size and spectral properties of the CdSe core of the nanoparticles are controlled by adjustment of the residence time and the temperature. As a second step, the zinc sulfide capping under homogenous conditions is carried out at a substantially lower temperature than is required for nanoparticle growth in batch processes. Finally, the trioctylphosphine/oleic acid ligand is effectively replaced with either carbohydrate PEG-thiol moieties or DHLA at 60 °C. This new protocol allows the synthesis of biologically active fluorescent QDs in 4 d. PMID:21799489

Laurino, Paola; Kikkeri, Raghavendra; Seeberger, Peter H

2011-08-01

331

Increase of uric acid synthesis in irradiated chicken's embryos  

International Nuclear Information System (INIS)

Several important intermediate and end products of uric acid metabolism as well as their corresponding enzymatic reactions were studied in 16 day-old chicken embryos which had been one or more times irradiated or respectively treated with ammonium chloride. After sublethal X-irradiation and at the time of the second irradiation with 800 R, the activity of the glutamine synthetase and the xanthin dehydrogenase in the kidneys of the embryos was increased. In contrast to this the glutamate dehydrogenase activity was moderately decreased. Two hours after the main irradiation the uric acid values as well as the amount of fixed nitrogen in the blood serum of previously-irradiated embryos are noticeably higher than the comparative data in non-previously irradiated animals. The glutamic acid values increase after the second irradiation, but still remain lower than with the non-previously irradiated animals. I achieved concuring ressults when I treated the embryos with ammonium chloride instead of radiation. (orig./MG)

332

Creating carbon-carbon bonds with samarium diiodide for the synthesis of modified amino acids and peptides  

DEFF Research Database (Denmark)

In this perspective, an overview of our experiences on the application of samarium diiodide in organic synthesis for the preparation of amino acid and peptide analogues is presented. Three different carbon-carbon bond forming reactions are discussed, including side chain introductions, gamma-amino acid synthesis and acyl-like radical additions for the construction of C-C mimics of the peptidic bonds.

Ebran, Jean-Philippe; Jensen, Christina M

2006-01-01

333

ENANTIOSPECIFIC SYNTHESES OF INTERMEDIATES IN THE TOTAL SYNTHESIS OF PSEUDOMONIC ACIDS  

OpenAIRE

Enantiospecific syntheses of 1S,6S-3,7-dioxabicyclo[4.3.0]non-4-en-8-one (1) and of the enantiomer (2) from D- and L-arabinose respectively have been achieved by two different routes. The conversion of (1) to 6S-(3R-acetanilido)-3,6-dihydro-2H-pyranyl-N,N-dimethylacetamide (3), a key intermediate in the synthesis of pseudomonic acids, is described. © 1982.

Fleet, G.; Gough, M.

1982-01-01

334

Synthesis of methylphosphonic acid by marine microbes: a source for methane in the aerobic ocean  

OpenAIRE

Relative to the atmosphere, much of the aerobic ocean is supersaturated with methane; however, the source of this important greenhouse gas remains enigmatic. Catabolism of methylphosphonic acid by phosphorus-starved marine microbes, with concomitant release of methane, has been suggested to explain this phenomenon, yet methylphosphonate is not a known natural product, nor has it been detected in natural systems. Further, its synthesis from known natural products would require unknown biochemi...

Metcalf, William W.; Griffin, Benjamin M.; Cicchillo, Robert M.; Gao, Jiangtao; Janga, Sarath Chandra; Cooke, Heather A.; Circello, Benjamin T.; Evans, Bradley S.; Martens-habbena, Willm; Stahl, David A.; Donk, Wilfred A.

2012-01-01

335

Exercise, Amino Acids and Aging in the Control of Human Muscle Protein Synthesis  

OpenAIRE

In this review we discuss recent research in the field of human skeletal muscle protein metabolism characterizing the acute regulation of mammalian target of rapamycin complex (mTORC) 1 signaling and muscle protein synthesis (MPS) by exercise, amino acid nutrition and aging. Resistance exercise performed in the fasted state stimulates mixed MPS within 1 h post-exercise, which can remain elevated for 48 h. We demonstrate that the activation of mTORC1 signaling (and subsequently enhanced transl...

Walker, Dillon K.; Dickinson, Jared M.; Timmerman, Kyle L.; Drummond, Micah J.; Reidy, Paul T.; Fry, Christopher S.; Gundermann, David M.; Rasmussen, Blake B.

2011-01-01

336

Biaryl synthesis via decarboxylative Pd-catalyzed reactions of arenecarboxylic acids and diaryliodonium triflates.  

Science.gov (United States)

A novel simple and efficient synthesis of biaryls via a Pd-catalyzed decarboxylative cross-coupling reaction of arenecarboxylic acids and diaryliodonium triflates is described. The PdCl2/DPEphos catalytic system in the presence of Ag2CO3 in DMSO was found to be the most efficient. Various biaryls, including sterically hindered biaryls, were synthesized with yields ranging from 37 to 85%. PMID:18553969

Becht, Jean-Michel; Le Drian, Claude

2008-07-17

337

Lewis acid free high speed synthesis of nimesulide-based novel N-substituted cyclic imides  

Energy Technology Data Exchange (ETDEWEB)

The first synthesis of nimesulide-based novel cyclic imides has been accomplished via the reaction of an amine prepared from nimesulide with appropriate anhydrides in the presence of sodium acetate. Using this process a variety of N-substituted cyclic imides was prepared in good yields in glacial acetic acid. Some of the compounds synthesized showed anti-inflammatory activities when tested in vivo. (author)

Kankanala, Kavitha; Mukkanti, Khagga [JNT University Hyderabad, Kukatpally (India); Pal, Sarbani, E-mail: sarbani277@yahoo.co [MNR Degree and PG College, Kukatpally, Hyderabad (India). Dept. of Chemistry; Reddy, Vangala Ranga [Dr. Reddy' s Laboratories Ltd. Integrated Product Development, Bachupally, Hyderabad (India)

2010-07-01

338

[Synthesis and properties of nuclear hydroxylated derivatives of flufenamic acid and etofenamate (author's transl)].  

Science.gov (United States)

Synthesis of six nuclear hydroxylated derivatives of flufenamic acid and etofenamate (5-OH-, 4'-OH and 5,4'-(OH2) on a preparative scale is described. All compounds show low toxicity, but only weak anti-inflammatory activity in the rat paw kaolin edema test as compared to 2-(2-hydroxyethoxy)ethyl-N-(a,a,a-trifluoro-m-tolyl)-anthranilate (etofenamate, active substance of Rheumon Gel). PMID:7200776

Boltze, K H; Bäcker, U; Kreisfeld, H

1982-01-01

339

NOVEL 3-ACETYLCOUMARIN SCHIFF’S BASE SYNTHESIS FROM DIFFERENT ACID HYDRAZIDE  

Directory of Open Access Journals (Sweden)

Full Text Available A new series of Schiff’s bases, SB1, SB2 and SB3 were synthesized from 3-acetylcoumarin and different acid hydrazides. The 3-acetyl coumarin was synthesized starting from salicylaldehyde and ethylacetoacetate. The structures of the synthesized compounds have been established on the basis of physical and spectral data. They shows a prominent absorption of -(C=N- in FTIR. A survey of existing literature revealed that there are no reports describing the synthesis of such hydrazones.

Anees Pangal

2013-10-01

340

Microwave-assisted synthesis of indole-2-carboxylic acid esters in ionic liquid  

International Nuclear Information System (INIS)

An improved procedure for the synthesis of indole-2-carboxylic acid esters in excellent yields has been achieved by the condensation of 2-halo aryl aldehydes or ketones and ethyl isocyanoacetate using ionic liquid under controlled microwave irradiation (100 W) at 50 deg C. This method offers a number of advantages in terms of methodology, high-product yield, short period of conversion, mild reaction conditions and easy workup. (author)

341

Microwave-assisted synthesis of indole-2-carboxylic acid esters in ionic liquid  

Energy Technology Data Exchange (ETDEWEB)

An improved procedure for the synthesis of indole-2-carboxylic acid esters in excellent yields has been achieved by the condensation of 2-halo aryl aldehydes or ketones and ethyl isocyanoacetate using ionic liquid under controlled microwave irradiation (100 W) at 50 deg C. This method offers a number of advantages in terms of methodology, high-product yield, short period of conversion, mild reaction conditions and easy workup. (author)

Gu, Lijun [Key Laboratory of Ethnic Medicine Resource Chemistry, Yunnan University of Nationalities, State Ethnic Affairs Commission and Ministry of Education of P. R. China, Kunming (China); Li, Xiangguang [Department of Chemistry, Northwest University, Xi' an (China)

2011-09-15

342

Total synthesis of the novel, biologically active epoxyquinone dimer (+/-)-torreyanic acid: a biomimetic approach.  

Science.gov (United States)

[reaction: see text] A total synthesis of the complex, biologically active, dimeric natural product (+/-)-torreyanic acid, which is composed of seven rings and laced with dense, variegated oxy-functionalization, has been accomplished from readily available allyl-substituted p-benzoquinone 8. Our synthetic stratagem involves crafting an epoxyquinone monomer for use in a biomimetic cascade process involving tandem a 6pi electrocyclization and a Diels-Alder dimerization. PMID:15496080

Mehta, Goverdhan; Pan, Subhas Chandra

2004-10-28

343

Efficient synthesis of gamma-alkylidenetetronic esters by sequential Lewis acid catalyzed.  

Science.gov (United States)

A new approach for the synthesis of gamma-alkylidenetetronic acids and esters is reported which involves Me3SiOTf-catalyzed, regio- and stereoselective cyclization of 4-alkoxy-1,3-bis(trimethylsilyloxy)-1,3-butadienes with oxalyl chloride. The alpha-hydroxy group of the butenolides is efficiently functionalized by palladium-catalyzed cross-coupling reactions via the corresponding enol triflates. PMID:11281759

Langer, P; Eckardt, T; Schneider, T; Göbel, C; Herbst-Irmer, R

2001-04-01

344

Synthesis, Crystal Structure and Biological Activity of 2-Hydroxyethylammonium Salt of p-Aminobenzoic Acid  

OpenAIRE

p-Aminobenzoic acid (pABA) plays important roles in a wide variety of metabolic processes. Herein we report the synthesis, theoretical calculations, crystallographic investigation, and in vitro determination of the biological activity and phytotoxicity of the pABA salt, 2-hydroxyethylammonium p-aminobenzoate (HEA-pABA). The ability of neutral and anionic forms of pABA to interact with TIR1 pocket was investigated by calculation of molecular electrostatic potential maps on the accessible surfa...

Crisan, Manuela E.; Bourosh, Paulina; Maffei, Massimo E.; Forni, Alessandra; Pieraccini, Stefano; Sironi, Maurizio; Chumakov, Yurii M.

2014-01-01

345

Enzymatic synthesis of arbutin undecylenic acid ester and its inhibitory effect on melanin synthesis.  

Science.gov (United States)

Transesterification of arbutin and undecylenic acid vinyl ester was catalyzed by alkaline protease, Bioprase, in dimethylformamide to get arbutin derivative having undecylenic acid at 6-position of glucose moiety, 6-O-undecylenoyl p-hydroxyphenyl beta-D-glucopyranoside. The reaction rate increased with increase of arbutin concentration, and when its concentration was 0.9 M, the conversion rate was more than 90% under addition of 2 M undecylenic acid vinyl ester. The obtained arbutin ester significantly suppressed melanin production in murine B16 melanoma cells. PMID:17418566

Tokiwa, Yutaka; Kitagawa, Masaru; Raku, Takao; Yanagitani, Shusaku; Yoshino, Kenji

2007-06-01

346

Synthesis and sintering of nanocrystalline hydroxyapatite powders by citric acid sol-gel combustion method  

International Nuclear Information System (INIS)

The citric acid sol-gel combustion method has been used for the synthesis of nanocrystalline hydroxyapatite (HAP) powder from calcium nitrate, diammonium hydrogen phosphate and citric acid. The phase composition of HAP powder was characterized by X-ray powder diffraction analysis (XRD). The morphology of HAP powder was observed by transmission electron microscope (TEM). The HAP powder has been sintered into microporous ceramic in air at 1200 deg. C with 3 h soaking time. The microstructure and phase composition of the resulting HAP ceramic were characterized by scanning electron microscope (SEM) and XRD, respectively. The physical characterization of open porosity and flexural strength have also been carried out

347

Synthesis and NMR elucidation of novel octa-amino acid resorcin[4]arenes derivatives  

Scientific Electronic Library Online (English)

Full Text Available The synthesis of nine novel protected amino acid cavitands is reported. All have four pendant M-undecyl chains and 'headgroups' connected by a two-carbon spacer at eight positions on the aromatic rings. The amino acids employed are glycine, alanine, phenylalanine, leucine, proline, tryptophan, serin [...] e, glutamine and lysine. The structures of the compounds were elucidated using one and two-dimensional NMR techniques which verified that all octa-substituted cavitands have symmetrical C2v conformation at room temperature. These compounds have potential synthetic ion channel applications.

Iman, Elidrisi; Pralav V., Bhatt; Thavendran, Govender; Hendrik G., Kruger; Glenn E. M., Maguire.

348

Concise and Straightforward Asymmetric Synthesis of a Cyclic Natural Hydroxy-Amino Acid  

Directory of Open Access Journals (Sweden)

Full Text Available An enantioselective total synthesis of the natural amino acid (2S,4R,5R-4,5-di-hydroxy-pipecolic acid starting from D-glucoheptono-1, 4-lactone is presented. The best sequence employed as a key step the intramolecular nucleophilic displacement by an amino function of a 6-O-p-toluene-sulphonyl derivative of a methyl D-arabino-hexonate and involved only 12 steps with an overall yield of 19%. The structures of the compounds synthesized were elucidated on the basis of comprehensive spectroscopic (NMR and MS and computational analysis.

Mario J. Simirgiotis

2014-11-01

349

Biological synthesis of ferulic and sinapic acids labelled with 14C  

International Nuclear Information System (INIS)

14CH3 labelled ferulic and sinapic acids have been synthesized through an enzymic methylation of caffeic and 5-hydroxyferulic acids using labelled S-adenosyl methionine as 14CH3 donor. The methyltransferases involved which were extracted from stems of Poplar catalyse these reactions with a good efficiency. A purification procedure of 14C S-adenosyl methionine is described which allows the recycling of 14CH3 donor. The yield of the overall process is therefore greatly improved. This method allows the synthesis of products with high specific radioactivity. (author)

350

1,4-Diazoniabicyclo[2.2.2]octane terephthalate  

OpenAIRE

In the title compound, C6H14N2+·C8H4O42?, the protonated 1,4-diazoniabicyclo[2.2.2]octane cations and the deprotonated terephthalate anions are alternately linked by N—H...O hydrogen bonds into chains.

Jian-Wei Zhu; Xu-Chun Song; Yang, E.

2008-01-01

351

Radiation effect in polyethylene terephthalate under charged particle action  

International Nuclear Information System (INIS)

The modification of polyethylene terephthalate (PET) composition under high-energy electrons and heavy charged particles bombardment by the methods of Rutherford backscattering and recoiling are studied. The changes in composition of oxygen and hydrogen, optical transparency of PET during ion irradiation are presented

352

Deposition of multilayered protein coating onto poly(ethylene terephthalate).  

Czech Academy of Sciences Publication Activity Database

Ro?. 45, 9-10 (2003), s. 267-271. ISSN 1560-0904 R&D Projects: GA AV ?R IAA4050006; GA ?R GA203/02/1326 Institutional research plan: CEZ:AV0Z4050913 Keywords : protein multilayers * poly(ethylene terephthalate) Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.405, year: 2003

Solovyev, A.; Brynda, Eduard; Houska, Milan; Bleha, Miroslav; Shataeva, L.

2003-01-01

353

76 FR 8770 - Polyethylene Terephthalate (Pet) Film From Korea  

Science.gov (United States)

...terephthalate (PET) film from Korea...antidumping order on PET film from Korea would be likely to lead to a...antidumping order on PET film from Korea. For further information concerning...202-205- 1810. Persons with mobility impairments who will need...

2011-02-15

354

Synthesis of Oligomers of 12-Acryloyloxydodecanoic Acid via Reversible Addition Fragmentation Transfer (RAFT Polymerisation  

Directory of Open Access Journals (Sweden)

Full Text Available A long chain fatty acid carrying an acryloyl functionality, 12-acryloyloxydodecanoic acid (12-ADA, was preparedfrom 11-hydroxydodecanoic acid and acryloyl chloride and used as monomer in the synthesis of oligomers of 12-ADAvia the RAFT controlled polymerisation process. Reversible Addition Fragmentation Transfer (RAFT reagents wereprepared and used to control the polymerisation process and produced an oligomeric product with few monomeric unitsinstead of a high molecular weight polymer of 12-ADA. The transfer reagents were prepared from Grignardintermediates from a reaction of dithioacids with free radical initiators 2,2-azobisisobutyronitrile (AIBN and4,4-azobis(4-cyanopropanoic acid (ACP. It was found that short-chain oligomers in the form of dimers and trimerscharacterized by Electrospray Mass Spectrometry, ESMS and Gel Permeation chromatography, GPC were the majorproducts obtained when RAFT reagents had been used in the controlled polymerisation. As a control, polymerisationwas carried out in the absence of RAFT reagents and high molecular-weight polymers were obtained. This confirmedthe effectiveness of the prepared RAFT reagents as polymerisation controllers and provided a way for the synthesis ofoligomers. Here, the preparation of oligomers of 12-ADA using AIBN-RAFT reagents is reported. The method isexpected to provide one way of preparing oligomers of controlled chain length/molecular mass which also carry acarboxylic acid functional group at one end.

Lilian Tichagwa

2009-07-01

355

Ionic liquids as novel solvents for the synthesis of sugar fatty acid ester.  

Science.gov (United States)

Sugar fatty acid esters are bio-surfactants known for their non-toxic, non-ionic, and high biodegradability . With great emulsifying and conditioning effects, sugar fatty acids are widely used in the food, pharmaceutical, and cosmetic industries. Biosynthesis of sugar fatty acid esters has attracted growing attention in recent decades. In this study, the enzymatic synthesis of sugar fatty acid esters in ionic liquids was developed, optimized, and scaled up. Reaction parameters affecting the conversion yield of lipase-catalyzed synthesis of glucose laurate from glucose and vinyl laurate (i.e. temperature, vinyl laurate/glucose molar ratio, and enzyme loads) were optimized by response surface methodology (RSM). In addition, production was scaled up to 2.5 L, and recycling of enzyme and ionic liquids was investigated. The results showed that under optimal reaction conditions (66.86 °C, vinyl laurate/glucose molar ratio of 7.63, enzyme load of 73.33 g/L), an experimental conversion yield of 96.4% was obtained which is close to the optimal value predicted by RSM (97.16%). A similar conversion yield was maintained when the reaction was carried out at 2.5 L. Moreover, the enzymes and ionic liquids could be recycled and reused effectively for up to 10 cycles. The results indicate the feasibility of ionic liquids as novel solvents for the biosynthesis of sugar fatty acid esters. PMID:25124865

Mai, Ngoc Lan; Ahn, Kihun; Bae, Sang Woo; Shin, Dong Woo; Morya, Vivek Kumar; Koo, Yoon-Mo

2014-12-01

356

On the synthesis of 11C-labelled aromatic amino acids  

International Nuclear Information System (INIS)

The use of 11C-labelled aromatic amino acids in positron emission tomography (PET) and their importance in physiological studies, especially cerebral protein synthesis or their role as precursors of neurotransmitters, is discussed. The synthesis of 11-C-labelled aromatic amino acids by various routes is presented and new 11C-labelled precursors, aromatic and aliphatic 11C-aldehydes, are reported. The 11C-aldehydes were obtained in 60-95% radiochemical yield and reaction times were of the order of 5 min. The 11C-aldehydes have been used in condensation reactions with 2-aryl-5-oxazolones in the presence of a tertiary amine, diazabicyclooctane (DABCO), to produce the corresponding [?-11C]-4-arylene-2-aryl-5-oxazolones. Ring opening, hydrogenation and removal of protecting groups were carried out in one step to produce the racemic [3-11C]-labelled aromatic amino acids in 8-30% radiochemical yield. The total reaction time was 52-60 min. L-[3-11C]Phenylalanine was obtained by a seven-step synthesis in 80% e.e. (enantiomeric excess) and 60% e.e., respectively, in 10-15% radiochemical yield within 60 min, by use of the chiral rhodium complex of (R)-1,2-bis(diphenylphosphino)propane ((R)-PROPHOS) or (+)-2,3-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane ((+)-DIOP) in the hydrogenation reaction. Racemic [2-11C]-labelled aromatic amino acids were producedbelled aromatic amino acids were produced by a high-pressure, high-temperature modification of the Buechere-Strecker synthesis. [2-11C]Phenylglycine was obtained in 20% radiochemical yield within 50 min. [3-11C]Phenylpyruvic acid was prepared via the aldehyde-oxyzolone condensation reaction in 40% radiochemical yield within 40 min (not including LC separation). Its use in the synthesis of [3-11C]-phenylalanine by enzymatic transamination is also discussed. With 32 refs.(Author)

357

Synthesis of [2-[sup 14]C] griseolic acid 9'-(4-acetoxy-3-methoxybenzyl)ester, a antiglaucoma agent  

Energy Technology Data Exchange (ETDEWEB)

Starting from [[sup 14]C] ethyl orthoformate an amidine derivative derived from griseolic acid in 6 steps, the synthesis of [2-[sup 14]C] griseolic acid 9'-(4-acetoxy-3-gethoxybenzyl)ester [14C], a promising antiglaucoma agent with its regioisomer [2-[sup 14]C] griseolic acid 8'-(4-acetoxy-3-gethoxybenzyl)ester and [2-[sup 14]C] griseolic acid [14C] has been achieved. (Author).

Sato, Susumu; Mikoshiba, Isamu; Kawai, Kenji; Hirai, Koichi (Sankyo Co. Ltd., Tokyo (Japan))

1993-01-01

358

Synthesis of [2-14C] griseolic acid 9'-(4-acetoxy-3-methoxybenzyl)ester, a antiglaucoma agent  

International Nuclear Information System (INIS)

Starting from [14C] ethyl orthoformate an amidine derivative derived from griseolic acid in 6 steps, the synthesis of [2-14C] griseolic acid 9'-(4-acetoxy-3-gethoxybenzyl)ester [14C], a promising antiglaucoma agent with its regioisomer [2-14C] griseolic acid 8'-(4-acetoxy-3-gethoxybenzyl)ester and [2-14C] griseolic acid [14C] has been achieved. (Author)

359

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

International Nuclear Information System (INIS)

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

360

Construction of recombinant Bacillus subtilis strains for efficient pimelic acid synthesis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english As a precursor, pimelic acid plays an important role in biotin biosynthesis pathway of Bacillus subtilis. Fermentations supplemented with pimelic acid could improve the production of biotin, however, with a disadvantage-high cost. So it is necessary to improve the biosynthesis of pimelic acid via ge [...] netic engineering in B. subtilis. In this study, we constructed a recombinant B. subtilis strain for improving the synthesis of pimelic acid, in which a maltose-inducible Pglv promoter was inserted into the upstream of the cistron bioI-orf2-orf3 and, meanwhile, flanked by the tandem cistrons via a single crossover event. The copy number of the integrant was amplified by high-concentration resistance screen and increased to 4-5 copies. The production of pimelic acid from multiple copies integrant was about 4 times higher than that from single copy (1017.13 ?g/ml VS. 198.89 ?g/ml). And when induced by maltose the production of pimelic acid was about 2 times of that under non-induction conditions (2360.73 ?g/ml VS. 991.59 ?g/ml). Thus, these results demonstrated that the production of pimelic acid was improved obviously through reconstructed B. subtilis. It also suggested that our expression system provided a convenient source of pimelic acid that would potentially lower the cost of production of biotin from engineered B. subtilis.

Wei-Wei, Zhang; Ming-Ming, Yang; Heng-xin, Li; Dun, Wang.

2011-11-15

361

[Design, synthesis and antitumor activity of valproic acid salicylanilide esters].  

Science.gov (United States)

A series of valproic acid salicylanilide esters were designed and synthesized based on the principle of prodrug. The structures of the target compounds were confirmed by MS, 1H NMR and 13C NMR. Anti-tumor activities of these compounds against K562, A549, A431 cells in vitro were investigated by MTT assay and SRB assay. The results indicated that the compounds 6h-6j were found to have stronger cell growth inhibitory action than gefitinib, and comparable to niclosamide, which are worth to be intensively studied further. PMID:23984521

Yuan, Ming; Li, Jia-Ming; He, Guang-Wei; Zhong, Guo-Chen; Zhang, Yan-Chun

2013-06-01

362

Synthesis and scale inhibitor performance of polyaspartic acid.  

Science.gov (United States)

Polyaspartic acid (PASP) has been extensively studied in recent years as a green scale inhibitor. PASP was synthesized by thermal polycondensation of maleic anhydride and ammonium carbonate in this study. The optimal polycondensation reaction conditions were the raw material (maleic anhydride and ammonium carbonate) molar ratio of 1.0:1.2, the polymerization temperature of 180°C and reaction time of 2.0 hr. The results showed that PASP exhibits very good scale inhibiting performance. The inhibition rate was 95% for calcium carbonate and 90% for calcium sulfate by the application of 5 mg/L PASP. PMID:25084581

Liu, Zhengyan; Sun, Yonghong; Zhou, Xiaohui; Wu, Tao; Tian, Ying; Wang, Yingzhan

2011-06-01

363

Kinetics and mechanism of coupled synthesis of cyclohexanecarboxylic acid  

Science.gov (United States)

The effect of the nature of the anion in a palladium salt on a coupled process involving the oxidation of CO and hydrocarboxylation of cyclohexene in the PdX2-CuBr2-THF-H2O system was studied. The kinetics was investigated under the steady-state conditions. The kinetic isotope effects (H2O/D2O) for the rates of formation of CO2 and cyclohexanecarboxylic acid were measured. The mechanism of the coupled processes of hydrocarboxylation of cyclohexene involving the formation of palladium hydride complexes and their transformations was suggested. The kinetic model of the processes was obtained.

Putin, A. Yu.; Bychkova, E. Yu.; Trunilina, K. V.; Zakgeim, A. Yu.; Katsman, E. A.; Shishilov, O. N.; Akhmadullina, N. S.; Oshanina, I. V.; Temkin, O. N.; Bruk, L. G.

2015-03-01

364

Synthesis, Preliminary Bioevaluation and Computational Analysis of Caffeic Acid Analogues  

Directory of Open Access Journals (Sweden)

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

Zhiqian Liu

2014-05-01

365

A Direct, Biomass-Based Synthesis of Benzoic Acid: Formic Acid-Mediated Deoxygenation of the Glucose-Derived Materials Quinic Acid and Shikimic Acid  

Energy Technology Data Exchange (ETDEWEB)

An alternative biomass-based route to benzoic acid from the renewable starting materials quinic acid and shikimic acid is described. Benzoic acid is obtained selectively using a highly efficient, one-step formic acid-mediated deoxygenation method.

Arceo, Elena; Ellman, Jonathan; Bergman, Robert

2010-05-03

366

Effect of addition of tartaric acid on synthesis of boron carbide powder from condensed boric acid–glycerin product  

Energy Technology Data Exchange (ETDEWEB)

Highlights: •B{sub 4}C powder was synthesized from a condensed H{sub 3}BO{sub 3}-glycerin product with tartaric acid added. •A precursor consisting of B{sub 2}O{sub 3} and carbon was prepared by the thermal decomposition in air. •The precursors had a three-dimensional bicontinuous B{sub 2}O{sub 3}/carbon network structure. •The dispersion state became more homogeneous and finer with the addition of tartaric acid. •The complete formation of B{sub 4}C powder was achieved at 1250 °C within a shorter heat treatment time. -- Abstract: The effect of the addition of tartaric acid on the synthesis of boron carbide (B{sub 4}C) powder from a condensed boric acid (H{sub 3}BO{sub 3})–glycerin product was investigated in this study. The condensed product was prepared by dehydration condensation after directly mixing equimolar amounts of H{sub 3}BO{sub 3} and glycerin with the addition of 0–50 mol% tartaric acid (based on glycerin), which was followed by thermal decomposition in air to obtain a precursor powder from which excess carbon had been eliminated. The dispersion state of the boron oxide (B{sub 2}O{sub 3}) and carbon components in the precursor prepared from the condensed product with 25 mol% tartaric acid added was finer than that without tartaric acid added, in which both precursors had a three-dimensional bicontinuous B{sub 2}O{sub 3}/carbon network structure. The complete formation of crystalline B{sub 4}C powder was achieved at 1250 °C within a shorter heat treatment time for the precursor with a fine dispersion state. The synthesized B{sub 4}C powders became fine owing to the increased number of nucleation sites.

Tahara, Naoki; Kakiage, Masaki, E-mail: kakiage@apc.saitama-u.ac.jp; Yanase, Ikuo; Kobayashi, Hidehiko

2013-10-05

367

Effect of addition of tartaric acid on synthesis of boron carbide powder from condensed boric acid–glycerin product  

International Nuclear Information System (INIS)

Highlights: •B4C powder was synthesized from a condensed H3BO3-glycerin product with tartaric acid added. •A precursor consisting of B2O3 and carbon was prepared by the thermal decomposition in air. •The precursors had a three-dimensional bicontinuous B2O3/carbon network structure. •The dispersion state became more homogeneous and finer with the addition of tartaric acid. •The complete formation of B4C powder was achieved at 1250 °C within a shorter heat treatment time. -- Abstract: The effect of the addition of tartaric acid on the synthesis of boron carbide (B4C) powder from a condensed boric acid (H3BO3)–glycerin product was investigated in this study. The condensed product was prepared by dehydration condensation after directly mixing equimolar amounts of H3BO3 and glycerin with the addition of 0–50 mol% tartaric acid (based on glycerin), which was followed by thermal decomposition in air to obtain a precursor powder from which excess carbon had been eliminated. The dispersion state of the boron oxide (B2O3) and carbon components in the precursor prepared from the condensed product with 25 mol% tartaric acid added was finer than that without tartaric acid added, in which both precursors had a three-dimensional bicontinuous B2O3/carbon network structure. The complete formation of crystalline B4C powder was achieved at 1250 °C within a shorter heat treatment time for the precursor with a fine dispersion state. The synthesized B4C powders became fine owing to the increased number of nucleation sites

368

Enantiopure synthesis of dihydrobenzo[1,4]-oxazine-3-carboxylic acids and a route to benzoxazinyl oxazolidinones.  

Science.gov (United States)

A two step protocol is developed for the efficient synthesis of enantiopure N-Boc-dihydrobenzo[b]-1,4-oxazine-3-carboxylic acids from serine derived cyclic sulfamidate via intramolecular arylamination. The RuPhos Palladacycle along with additional RuPhos ligand is found to be an efficient catalyst for the arylamination of ?-(2-bromoaryloxy)amino acids to provide easy and direct access to a variety of dihydrobenzo[b]-1,4-oxazine-3-carboxylic acids with complete retention of enantiopurity in moderate to high yields. Dihydrobenzo[b]-1,4-oxazine-3-carboxylic acids are not only important unnatural amino acids, but are key precursors for the synthesis of important compounds such as benzoxazinyl oxazolidinones. A general approach for the synthesis of benzoxazinyl oxazolidinone is presented. PMID:25645529

Malhotra, Rajesh; Dey, Tushar K; Basu, Sourav; Hajra, Saumen

2015-03-01

369

Biotransformation and Stereoselective Synthesis of Pharmaceutical Molecules from Linoleic Acid  

Directory of Open Access Journals (Sweden)

Full Text Available The biotransformation of linoleic acid 1 using immobilised soybean lipoxygenase in a dimethyl sulfoxide (DMSO containing medium followed by sodium borohydride reduction afforded 13(S-hydroxy-octadeca-9(Z,11(E-dienoic acid 13(S-HODE 2 in 69% yield. After methylation, methyl 13(S-HODE was subjected to epoxidation using tert-butyl hydroperoxide (TBHP in the presence of vanadyl acetylacetonate or titanium (IV isopropoxide with D-(-- or L-(+-diisopropyl tartrate. Epoxidation catalysed by titanium (IV isopropoxide/D-(--isopropyl tartarate gave predominantly epoxide 3 (in 75% yield while treatment of 2 with TBHP in the presence of titanium (IV isopropoxide and L-(+-diisopropyl tartrate gave preferentially epoxide 4 in 73% yield. Meanwhile, epoxidation of 2 with TBHP in the presence of vanadyl acetylacetonate gave predominantly epoxide 3 in 72% yield. The fluoro-derivatives 8, 9 and 10 were obtained in high yield when hydroxy-derivative 2, 3 and 4 were converted into their trimethylsilyl derivatives 5, 6 and 7 before treating with diethylaminosulphur trifluoride. Treatment of epoxide 4 with acetamide in dimethyl formamide (DMF afforded a heterocyclic 2-oxazoline 11 in 73% yield.

Muhammad Nor bin Omar

2007-01-01

370

Trans-10, cis-12 conjugated linoleic acid decreases de novo lipid synthesis in human adipocytes.  

Science.gov (United States)

Conjugated linoleic acid (CLA) reduces adiposity in vivo. However, mechanisms mediating these changes are unclear. Therefore, we treated cultures of human adipocytes with trans-10, cis-12 (10,12) CLA, cis-9, trans-11 (9,11) CLA or other trans fatty acids (FA), and measured indices of lipid metabolism. The lipid-lowering effects of 10,12 CLA were unique, as other trans FA did not reduce TG content to the same extent. Using low levels of [(14)C]-CLA isomers, it was shown that both isomers were readily incorporated into acylglycerols and phospholipids, albeit at lower levels than [(14)C]-oleic or [(14)C]-linoleic acids. When using [(14)C]-acetic acid and [(14)C]-pyruvic acid as substrates, 30 ?M 10,12 CLA, but not 9,11 CLA, decreased de novo synthesis of triglyceride, free FA, diacylglycerol, cholesterol esters, cardiolipin, phospholipids and ceramides within 3-24 h. Treatment with 30 ?M 10,12 CLA, but not 9,11 CLA, decreased total cellular lipids within 3 days and the ratio of monounsaturated FA (MUFA) to saturated FA, and increased C18:0 acyl-CoA levels within 24 h. Consistent with these data, stearoyl-CoA desaturase (SCD)-1 mRNA and protein levels were down-regulated by 10,12 CLA within 7-12 h, respectively. The mRNA levels of liver X receptor (LXR)? and sterol regulatory element binding protein (SREBP)-1c, transcription factors that regulate SCD-1, were decreased by 10,12 CLA within 5 h. These data suggest that the isomer-specific decrease in de novo lipid synthesis by 10,12 CLA is due, in part, to the rapid repression of lipogenic transcription factors that regulate MUFA synthesis, suggesting an anti-obesity mechanism unique to this trans FA. PMID:21775116

Obsen, Thomas; Faergeman, Nils J; Chung, Soonkyu; Martinez, Kristina; Gobern, Semone; Loreau, Olivier; Wabitsch, Martin; Mandrup, Susanne; McIntosh, Michael

2012-06-01

371

Synthesis of an acid addition salt of delta-aminolevulinic acid from 5-bromo levulinic acid esters  

Energy Technology Data Exchange (ETDEWEB)

A process is disclosed for preparing an acid addition salt of delta-aminolevulinic acid comprising. The process involves dissolving a lower alkyl 5-bromolevulinate and an alkali metal diformylamide in an organic solvent selected from the group consisting of acetonitrile, methanol, tetrahydrofuran, 2-methyltetrahydrofuran and methylformate or mixtures to form a suspension of an alkyl 5-(N,N-diformylamino) levulinate ester; and hydrolyzing the alkyl 5-(N,N-diformylamino) levulinate with an inorganic acid to form an acid addition salt of delta-amino levulinic acid.

Moens, L.

1999-05-25

372

THE USE OF FATTY ACID-ESTERS TO ENHANCE FREE ACID SOPHOROLIPID SYNTHESIS  

Science.gov (United States)

Fatty acid esters were prepared by transesterification of soy oil with methanol (methyl-soyate, Me-Soy), ethanol (ethyl-soyate, Et-Soy) and propanol (propyl-soyate, Pro-Soy) and used with glycerol as fermentation substrates to enhance production of free-acid sophorolipids (SLs). Fed-batch fermentat...

373

Synthesis and biological activity of amino acid conjugates of abscisic acid.  

Science.gov (United States)

We prepared 19 amino acid conjugates of the plant hormone abscisic acid (ABA) and investigated their biological activity, enzymatic hydrolysis by a recombinant Arabidopsis amidohydrolases GST-ILR1 and GST-IAR3, and metabolic fate in rice seedlings. Different sets of ABA-amino acids induced ABA-like responses in different plants. Some ABA-amino acids, including some that were active in bioassays, were hydrolyzed by recombinant Arabidopsis GST-IAR3, although GST-ILR1 did not show hydrolysis activity for any of the ABA-amino acids. ABA-L-Ala, which was active in all the bioassays, an Arabidopsis seed germination, spinach seed germination, and rice seedling elongation assays, except in a lettuce seed germination assay and was hydrolyzed by GST-IAR3, was hydrolyzed to free ABA in rice seedlings. These findings suggest that some plant amidohydrolases hydrolyze some ABA-amino acid conjugates. Because our study indicates the possibility that different plants have hydrolyzing activity toward different ABA-amino acids, an ABA-amino acid may function as a species-selective pro-hormone of ABA. PMID:21310619

Todoroki, Yasushi; Narita, Kenta; Muramatsu, Taku; Shimomura, Hajime; Ohnishi, Toshiyuki; Mizutani, Masaharu; Ueno, Kotomi; Hirai, Nobuhiro

2011-03-01

374

Diphenylparabanic acid as a synthon for the synthesis of ?-diketones and ?-ketocarboxylic acids.  

Science.gov (United States)

Diphenylparabanic acid was found to react with >2 equiv of organolithiums at -78 °C to effectively give the corresponding symmetrical ?-diketones. However, upon treatment with 1 equiv of organolithium, the parabanic acid gave mainly 5-substituted 5-hydroxyimidazolidine-2,4-diones. On the other hand, Grignard reagents were less reactive toward the parabanic acid at low temperature, and selectively gave the corresponding 5-hydroxyimidazolidine-2,4-diones even if more than 1 equiv of the reagents was used. A tandem process in which the parabanic acid was first reacted with a Grignard reagent and then reacted in one-pot with an organolithium effectively gave the unsymmetrical ?-diketone. 5-Substituted 5-hydroxyimidazolidine-2,4-diones were useful as versatile precursors for preparing ?-ketocarboxylic acids as well as unsymmetrical ?-diketones. PMID:22136154

Watanabe, Nobuko; Hamano, Mitsutaka; Todaka, Shota; Asaeda, Takahiro; Ijuin, Hisako K; Matsumoto, Masakatsu

2012-01-01

375

Synthesis of nalidixic acid based hydrazones as novel pesticides.  

Science.gov (United States)

Thirty-one substituted hydrazones of nalidixic acid hydrazide were synthesized and characterized by spectral techniques. These compounds were evaluated for various biological activities, namely, fungicidal, insecticidal, and nitrification inhibitory activities. The antifungal activity was evaluated against five pathogenic fungi, namely, Rhizoctonia bataticola , Sclerotium rolfsii , Rhizoctonia solani , Fusarium oxysporum , and Alternaria porii . They showed maximum inihibition against A. porii with ED(50) = 34.2-151.3 microg/mL. The activity was comparable to that of a commercial fungicide, hexaconazole (ED(50) = 25.4 microg/mL). They were also screened for insecticidal activity against third-instar larvae of Spodoptera litura and adults of Callosobruchus maculatus and Tribollium castaneum . Most of them showed 70-100% mortality against S. litura through feeding method at 0.1% dose. These compounds were not found to be effective nitrification inhibitors. PMID:20131903

Aggarwal, Nisha; Kumar, Rajesh; Srivastva, Chitra; Dureja, Prem; Khurana, J M

2010-03-10

376

Synthesis of tyrosine derivatives containing boric acid moiety  

Energy Technology Data Exchange (ETDEWEB)

While p-boronophenylalanine (p-BPA) is known as a useful pharmaceutical for Boron Neutron Capture Therapy (BNCT), it is also reported that the boron content after it is accumulated in melanomas decreases gradually with time. 2-hydroxy-5-(2' carboxy-2'-aminoethyl) phenyl boric acid (HBPA) is suggested for alternative candidate to be used, as the compound (HBPA) resembles more in chemical nature to tyrosine and is more difficult to be oxidized by tyrosinase than p-BPA. The authors tried to synthesize HBPA via isocyanoethylacetate, employing 1-bromo-2-methoxy-5-methylbenzene as a starting material. The structure of the synthesized compounds at each steps in the course of the scheme was determined using {sup 1}H, {sup 13}C and {sup 11}B NMR spectrometer. (S. Ohno)

Kitazawa, M.; Yoshino, Kazuo [Shinshu Univ., Faculty of Science, Matsumoto, Nagano (Japan); Kimura, M.

1998-12-01

377

Synthesis of tyrosine derivatives containing boric acid moiety  

International Nuclear Information System (INIS)

While p-boronophenylalanine (p-BPA) is known as a useful pharmaceutical for Boron Neutron Capture Therapy (BNCT), it is also reported that the boron content after it is accumulated in melanomas decreases gradually with time. 2-hydroxy-5-(2' carboxy-2'-aminoethyl) phenyl boric acid (HBPA) is suggested for alternative candidate to be used, as the compound (HBPA) resembles more in chemical nature to tyrosine and is more difficult to be oxidized by tyrosinase than p-BPA. The authors tried to synthesize HBPA via isocyanoethylacetate, employing 1-bromo-2-methoxy-5-methylbenzene as a starting material. The structure of the synthesized compounds at each steps in the course of the scheme was determined using 1H, 13C and 11B NMR spectrometer. (S. Ohno)

378

Radiation synthesis of nanosilver nanohydrogels of poly(methacrylic acid)  

Science.gov (United States)

Nanosilver nanohydrogels (nSnH) of poly(methacrylic acid) were synthesized and stabilized using gamma irradiation. The main objective of this study was to develop silver nanoparticles and to evaluate the antimicrobial activity. Radiation helps in the polymerization, crosslinking and reduction of silver nitrate as well. Highly stable and uniformly distributed silver nanoparticles have been obtained within hydrogel network by water in oil nanoemulsion polymerization and were evaluated by dynamic light scattering (DLS) and transmission electron microscopy (TEM) respectively. TEM showed almost spherical and uniform distribution of silver nanoparticles through the hydrogel network. The mean size of silver nanoparticles ranging is 10-50 nm. The nanohydrogels showed good swelling in water. Antibacterial studies of nSnH suggest that it can be a good candidate as coating material in biomedical applications.

Gupta, Bhuvanesh; Gautam, Deepti; Anjum, Sadiya; Saxena, Shalini; Kapil, Arti

2013-11-01

379

Synthesis and cholinesterase inhibition of cativic acid derivatives.  

Science.gov (United States)

Alzheimer's disease (AD) is a neurodegenerative disorder associated with memory impairment and cognitive deficit. Most of the drugs currently available for the treatment of AD are acetylcholinesterase (AChE) inhibitors. In a preliminary study, significant AChE inhibition was observed for the ethanolic extract of Grindelia ventanensis (IC??=0.79 mg/mL). This result prompted us to isolate the active constituent, a normal labdane diterpenoid identified as 17-hydroxycativic acid (1), through a bioassay guided fractionation. Taking into account that 1 showed moderate inhibition of AChE (IC??=21.1 ?M), selectivity over butyrylcholinesterase (BChE) (IC??=171.1 ?M) and that it was easily obtained from the plant extract in a very good yield (0.15% w/w), we decided to prepare semisynthetic derivatives of this natural diterpenoid through simple structural modifications. A set of twenty new cativic acid derivatives (3-6) was prepared from 1 through transformations on the carboxylic group at C-15, introducing a C2-C6 linker and a tertiary amine group. They were tested for their inhibitory activity against AChE and BChE and some structure-activity relationships were outlined. The most active derivative was compound 3c, with an IC?? value of 3.2 ?M for AChE. Enzyme kinetic studies and docking modeling revealed that this inhibitor targeted both the catalytic active site and the peripheral anionic site of this enzyme. Furthermore, 3c showed significant inhibition of AChE activity in SH-SY5Y human neuroblastoma cells, and was non-cytotoxic. PMID:25017625

Alza, Natalia P; Richmond, Victoria; Baier, Carlos J; Freire, Eleonora; Baggio, Ricardo; Murray, Ana Paula

2014-08-01

380

TORC1 inhibits GSK3-mediated Elo2 phosphorylation to regulate very long chain fatty acid synthesis and autophagy.  

Science.gov (United States)

Very long chain fatty acids (VLCFAs) are essential fatty acids with multiple functions, including ceramide synthesis. Although the components of the VLCFA biosynthetic machinery have been elucidated, how their activity is regulated to meet the cell's metabolic demand remains unknown. The goal of this study was to identify mechanisms that regulate the rate of VLCFA synthesis, and we discovered that the fatty acid elongase Elo2 is regulated by phosphorylation. Elo2 phosphorylation is induced upon inhibition of TORC1 and requires GSK3. Expression of nonphosphorylatable Elo2 profoundly alters the ceramide spectrum, reflecting aberrant VLCFA synthesis. Furthermore, VLCFA depletion results in constitutive activation of autophagy, which requires sphingoid base phosphorylation. This constitutive activation of autophagy diminishes cell survival, indicating that VLCFAs serve to dampen the amplitude of autophagy. Together, our data reveal a function for TORC1 and GSK3 in the regulation of VLCFA synthesis that has important implications for autophagy and cell homeostasis. PMID:24239358

Zimmermann, Christine; Santos, Aline; Gable, Kenneth; Epstein, Sharon; Gururaj, Charulatha; Chymkowitch, Pierre; Pultz, Dennis; Rødkær, Steven V; Clay, Lorena; Bjørås, Magnar; Barral, Yves; Chang, Amy; Færgeman, Nils J; Dunn, Teresa M; Riezman, Howard; Enserink, Jorrit M

2013-11-27

381

TORC1 Inhibits GSK3-Mediated Elo2 Phosphorylation to Regulate Very Long Chain Fatty Acid Synthesis and Autophagy  

DEFF Research Database (Denmark)

Very long chain fatty acids (VLCFAs) are essential fatty acids with multiple functions, including ceramide synthesis. Although the components of the VLCFA biosynthetic machinery have been elucidated, how their activity is regulated to meet the cell's metabolic demand remains unknown. The goal of this study was to identify mechanisms that regulate the rate of VLCFA synthesis, and we discovered that the fatty acid elongase Elo2 is regulated by phosphorylation. Elo2 phosphorylation is induced upon inhibition of TORC1 and requires GSK3. Expression of nonphosphorylatable Elo2 profoundly alters the ceramide spectrum, reflecting aberrant VLCFA synthesis. Furthermore, VLCFA depletion results in constitutive activation of autophagy, which requires sphingoid base phosphorylation. This constitutive activation of autophagy diminishes cell survival, indicating that VLCFAs serve to dampen the amplitude of autophagy. Together, our data reveal a function for TORC1 and GSK3 in the regulation of VLCFA synthesis that has important implications for autophagy and cell homeostasis.

Zimmermann, Christine; Santos, Aline

2013-01-01

382

Synthesis of acrylate functional telechelic poly(lactic acid) oligomer by transesterification.  

Science.gov (United States)

The controlled synthesis of low molecular weight (Mn from 700 to 10 000 g/mol) poly(lactic acid) (PLA) telechelic oligomers end-capped with acrylate groups by a one-step reaction was investigated. A transesterification reaction was carried out in solution with a Lewis acid titanium catalyst using a high molecular weight PLA and a low molar mass diacrylate. End-functionalization was demonstrated by proton NMR spectroscopy which was also used for quantitative analysis and number average molecular weight determination using the ratio between the acrylic chain ends to the main groups of poly(D,L-lactic acid). The formation of low molar mass oligomers from high molecular weight poly(lactic acid) was verified by gel permeation chromatography. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry showed that the above oligomerization was accompanied by the formation of cyclic compounds. By these means the feasability of a simple transesterification for a controlled synthesis of telechelic oligomers with molecular mass being a function of the added amount of diacrylate has been demonstrated. The glass transition temperatures of the elaborated oligomers varied from -35 to -5 degrees C. Subsequent thermal crosslinking was performed using benzoyl peroxide which enabled the formation of amorphous networks with Tg's close to the body temperature of 40 degrees C. Upon storage in a humid atmosphere the initially fairly hard and brittle networks became, due to hydrolysis, progressively more flexible thus demonstrating the potential biodegradability of these materials. PMID:15348001

Coullerez, G; Lowe, C; Pechy, P; Kausch, H H; Hilborn, J

2000-08-01

383

The use of fatty acid esters to enhance free acid sophorolipid synthesis.  

Science.gov (United States)

Fatty acid esters were prepared by transesterification of soy oil with methanol (methyl-soyate, Me-Soy), ethanol (ethyl-soyate, Et-Soy) and propanol (propyl-soyate, Pro-Soy) and used with glycerol as fermentation substrates to enhance production of free-acid sophorolipids (SLs). Fed-batch fermentations of Candida bombicola resulted in SL yields of 46 +/- 4 g/l, 42 +/- 7 g/l and 18 +/- 6 g/l from Me-Soy, Et-Soy, and Pro-Soy, respectively. Liquid chromatography with atmospheric pressure ionization mass spectrometry (LC/API-MS) showed that Me-Soy resulted in 71% open-chain SLs with 59% of those molecules remaining esterified at the carboxyl end of the fatty acids. Et-Soy and Pro-Soy resulted in 43% and 80% open-chain free-acid SLs, respectively (containing linoleic acid and oleic acid as the principal fatty acid species linked to the sophorose sugar at the omega-1 position), with no evidence of residual esterification. PMID:16555009

Ashby, Richard D; Solaiman, Daniel K Y; Foglia, Thomas A

2006-02-01

384

Facile synthesis of multiamino vinyl poly(amino acid)s for promising bioapplications.  

Science.gov (United States)

We presented a general and facile strategy to prepare biocompatible multiamino polymers. Series of new monomers were synthesized by esterification of 2-hydroxyethyl methacrylate (HEMA) and Boc-amino acids, such as Boc-l-phenylalanine, Boc-glycine, Boc-l-alanine, Boc-l-valine, and Boc-l-lysine. Subsequent vinyl polymerization of monomers gave rise to vinyl poly(amino acid)s with a side primary amino group at each unit if deprotected. Both atom transfer radical polymerization (ATRP) and conventional free radical polymerization (FRP) were employed to prepare the multiamino polymers. A well controlled effect upon molecular weight with the standard first-order kinetics was achieved in cases of ATRP, and high molecular weight polymers were obtained via FRP. MTT assay showed that cell survival rates for the multiamino polymers were almost maintained above 90% and that their cytotoxicities were much lower than that of linear PEI (PEI 25000). Zeta potential measurements demonstrated that the vinyl poly(amino acid)s are electropositive, and AFM measurements showed that the vinyl poly(amino acid)s could tightly condense DNA into granular structures at a suitable concentration. The combination of facile availability, controlled productivity, low cytotoxicity and strong binding ability with DNA promises the great potential of the novel multiamino polymers in bioapplications. PMID:21114313

Sun, Haiyan; Gao, Chao

2010-12-13

385

Radiation synthesis of nanosilver nanohydrogels of poly(methacrylic acid)  

International Nuclear Information System (INIS)

Nanosilver nanohydrogels (nSnH) of poly(methacrylic acid) were synthesized and stabilized using gamma irradiation. The main objective of this study was to develop silver nanoparticles and to evaluate the antimicrobial activity. Radiation helps in the polymerization, crosslinking and reduction of silver nitrate as well. Highly stable and uniformly distributed silver nanoparticles have been obtained within hydrogel network by water in oil nanoemulsion polymerization and were evaluated by dynamic light scattering (DLS) and transmission electron microscopy (TEM) respectively. TEM showed almost spherical and uniform distribution of silver nanoparticles through the hydrogel network. The mean size of silver nanoparticles ranging is 10–50 nm. The nanohydrogels showed good swelling in water. Antibacterial studies of nSnH suggest that it can be a good candidate as coating material in biomedical applications. - Highlights: • Nanosilver nanohydrogels of PMAA were synthesized and stabilized using ?-irradiation. • The mean size of silver nanoparticles ranging is 10–50 nm. • Antibacterial studies of nSnH suggest it to be a good candidate for biomedical applications

386

Synthesis of aminocarbonyl N-acylhydrazones by a three-component reaction of isocyanides, hydrazonoyl chlorides, and carboxylic acids.  

Science.gov (United States)

A novel one-pot multicomponent synthesis of ?-aminocarbonyl N-acylhydrazones starting from readily available hydrazonoyl chlorides, isocyanides, and carboxylic acids is reported. The strategy exploits the ability of the carboxylic acid as a third component to suppress all competing reactions between nitrile imines and isocyanides, channeling the course of the reaction toward the formation of this novel class of compounds. PMID:25259417

Giustiniano, Mariateresa; Meneghetti, Fiorella; Mercalli, Valentina; Varese, Monica; Giustiniano, Francesco; Novellino, Ettore; Tron, Gian Cesare

2014-10-17

387

Manganese-Catalyzed Synthesis of cis-?-Amino Acid Esters through Organometallic C?H Activation of Ketimines.  

Science.gov (United States)

Manganese-catalyzed C?H functionalization reactions of ketimines set the stage for the expedient synthesis of cis-?-amino acid esters through site- and regioselective alkene annulations. The organometallic C?H activation occurred efficiently with high functional group tolerance, delivering densely functionalized ?-amino acid derivatives with ample scope. PMID:25663350

Liu, Weiping; Zell, Daniel; John, Michael; Ackermann, Lutz

2015-03-23

388

Direct synthesis of formic acid from carbon dioxide by hydrogenation in acidic media.  

Science.gov (United States)

The chemical transformation of carbon dioxide into useful products becomes increasingly important as CO2 levels in the atmosphere continue to rise as a consequence of human activities. In this article we describe the direct hydrogenation of CO2 into formic acid using a homogeneous ruthenium catalyst, in aqueous solution and in dimethyl sulphoxide (DMSO), without any additives. In water, at 40?°C, 0.2?M formic acid can be obtained under 200?bar, however, in DMSO the same catalyst affords 1.9?M formic acid. In both solvents the catalysts can be reused multiple times without a decrease in activity. Worldwide demand for formic acid continues to grow, especially in the context of a renewable energy hydrogen carrier, and its production from CO2 without base, via the direct catalytic carbon dioxide hydrogenation, is considerably more sustainable than the existing routes. PMID:24886955

Moret, Séverine; Dyson, Paul J; Laurenczy, Gábor

2014-01-01

389

Determination of protein and amino acid digestibility in foods including implications of gut microbial amino acid synthesis.  

Science.gov (United States)

To meet the protein and amino acid requirements of individuals and of populations requires information not only about their requirements but also about the capacity of available foods to meet those requirements. Most of our current knowledge of the digestibility of food proteins and the methods to estimate it has been derived from work with animals. Because the microbiota of the large intestine alter the amino acid composition of the digesta, and because only trivial quantities of amino acids are absorbed intact from the large intestine, the current method of choice for assessing amino acid digestibility is ileal digestibility corrected for basal endogenous losses, that is, standardized ileal digestibility. For protein as a whole, however, because nitrogen absorbed in forms other than as amino acids can contribute to the nitrogen economy, the absorption of nitrogen over the whole digestive tract is the more appropriate measure. Most of the methods developed for estimating ileal amino acid outflow in animals are not directly applicable to man: the exception is the use of volunteers with an ileostomy. The flow and composition of ileal digesta in human subjects can also be measured by the infusion of a marker and withdrawal of samples through a naso-intestinal tube. However, this method is too demanding for routine use and is likely to be restricted to validating the application to humans of digestibility data obtained either from animals, of which the pig seems most suitable, or in vitro methods. Microbial activity in the gastrointestinal (GI) tract is not confined to the large intestine: the numbers and metabolic activity of the upper GI microbiota lead to substantial amounts of microbial protein leaving the ileum. It appears however that a large proportion of the amino acids used by the upper GI microbiota are preformed - from the diet or from endogenous materials - rather than from de novo synthesis. Although there are still uncertainties about the impact of microbial activity in the upper GI tract, the amino acid composition of ileal digesta provides the best available basis for estimating the proportion of dietary amino acids available for metabolism. PMID:23107534

Fuller, Malcolm

2012-08-01

390

Radiation synthesis of hydrogels with diprotic acid moieties and their use in the adsorption of biomolecules  

CERN Document Server

Radiation synthesis of diprotic acid moieties containing poly (N-vinyl 2- pyrrolidone) and polyacrylamide hydrogels and their use in the adsorption of biomolecules such as enzymes, proteins and drugs have been investigated. Hydrogels with varying cross-linked densities and ionic moieties were prepared from the ternary systems of N-vinyl 2-pyrrolidone/itaconic acid/water and acrylamide/maleic acid/water by irradiating with gamma rays at ambient temperature. For the characterization of network structure of hydrogels new equations were derived. Determination of average molecular weight between cross-links of hydrogels sensitive to pH changes of the swelling medium was investigated. In order to explain the influence of other external stimuli such as temperature and ionic strength of the swelling medium and the type of the buffer solution on the equilibrium swelling properties were investigated. The effect of these external stimuli on the biomolecule adsorption capacity of hydrogels were investigated for bovine se...

Sen, M

1996-01-01

391

Phenylalanine ammonia lyase catalyzed synthesis of amino acids by an MIO-cofactor independent pathway.  

Science.gov (United States)

Phenylalanine ammonia lyases (PALs) belong to a family of 4-methylideneimidazole-5-one (MIO) cofactor dependent enzymes which are responsible for the conversion of L-phenylalanine into trans-cinnamic acid in eukaryotic and prokaryotic organisms. Under conditions of high ammonia concentration, this deamination reaction is reversible and hence there is considerable interest in the development of PALs as biocatalysts for the enantioselective synthesis of non-natural amino acids. Herein the discovery of a previously unobserved competing MIO-independent reaction pathway, which proceeds in a non-stereoselective manner and results in the generation of both L- and D-phenylalanine derivatives, is described. The mechanism of the MIO-independent pathway is explored through isotopic-labeling studies and mutagenesis of key active-site residues. The results obtained are consistent with amino acid deamination occurring by a stepwise E1 cB elimination mechanism. PMID:24692092

Lovelock, Sarah L; Lloyd, Richard C; Turner, Nicholas J

2014-04-25

392

Synthesis of optically active dodecaborate-containing L-amino acids for BNCT  

Energy Technology Data Exchange (ETDEWEB)

A convenient and simple synthetic method of dodecaboratethio-L-amino acid, a new class of tumor-seeking boron carrier for BNCT, was accomplished from S-cyanoethylthioundecahydro-closo-dodecaborate (S-cyanoethyl-{sup 10}BSH, [{sup 10}B{sub 12}H{sub 11}]{sup 2-}SCH{sub 2}CH{sub 2}CN) and bromo-L-{alpha}-amino acids by nearly one step S-alkylation. An improved synthesis of S-cyanoethyl-{sup 10}BSH, a key starting compound for S-alkylation, was also performed by Michael addition of {sup 10}BSH with acryronitrile in high yield. Four kinds of new dodecaboratethio-L-amino acids were obtained in optically pure form without the need for any optical resolution.

Kusaka, Shintaro [Department of Bioscience and Informatics, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai (Japan); Hattori, Yoshihide, E-mail: y0shi_hattori@riast.osakafu-u.ac.jp [Department of Bioscience and Informatics, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai (Japan); Uehara, Kouki; Asano, Tomoyuki [Stella Pharma Corporation, ORIX Kouraibashi Bldg. 5F 3-2-7 Kouraibashi, Chuo-ku, Osaka (Japan); Tanimori, Shinji; Kirihata, Mitsunori [Department of Bioscience and Informatics, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai (Japan)

2011-12-15

393

Chemical synthesis of a synthetic analogue of the sialic acid-binding lectin siglec-7.  

Science.gov (United States)

As a basis for the development of an artificial carbohydrate-binding lectin, we chemically synthesized a domain of siglec-7, a well-characterized sialic-acid-binding lectin. The full polypeptide (127 amino acids) was constructed by sequential native chemical ligation (NCL) of five peptide segments. Because of poor cysteine availability for NCL, cysteine residues were introduced at suitable ligation sites; these cysteine residues were alkylated in order to mimic native glutamine or asparagine residues, or converted to an alanine residue by desulfurization after NCL. After folding the full-length polypeptide, the sialic-acid-binding activity of the synthetic siglec-7 was clearly demonstrated by STD NMR and ELISA experiments. We succeeded in the synthesis of siglec-7 by installing three extra cysteine residues with side-chain modifications and found that these modifications did not affect the binding activity. PMID:25277834

Izumi, Masayuki; Otsuki, Akihisa; Nishihara, Mika; Okamoto, Ryo; Kajihara, Yasuhiro

2014-11-24

394

Synthesis, characterization and spectroscopic study of Eu(III) complexes with 3-aminopicolinic acid derivatives  

International Nuclear Information System (INIS)

The synthesis, characterization and spectroscopic properties of lipophilic Eu(III) complexes of 3-aminopicolinic acid derivatives are reported. The stable complexes of Eu(III) with the ligands 3-dodecanoylaminopicolinic acid (3-NHCORpic) and 3-dodecanoylaminopicolinic acid N-oxide (3-NHCORpicNO) exhibit a remarkably high solubility in most common solvents and have enhanced luminescence and spectroscopic properties when compared with their parent 3-amino complexes. A strong absorption in the UV range, intense emission in the visible range, reasonable quantum yield and a long luminescence lifetime are observed. The results obtained show that these complexes can be used as light-conversion molecular devices either in solid state or in solution

395

Synthesis, characterization and spectroscopic study of Eu(III) complexes with 3-aminopicolinic acid derivatives  

Energy Technology Data Exchange (ETDEWEB)

The synthesis, characterization and spectroscopic properties of lipophilic Eu(III) complexes of 3-aminopicolinic acid derivatives are reported. The stable complexes of Eu(III) with the ligands 3-dodecanoylaminopicolinic acid (3-NHCORpic) and 3-dodecanoylaminopicolinic acid N-oxide (3-NHCORpicNO) exhibit a remarkably high solubility in most common solvents and have enhanced luminescence and spectroscopic properties when compared with their parent 3-amino complexes. A strong absorption in the UV range, intense emission in the visible range, reasonable quantum yield and a long luminescence lifetime are observed. The results obtained show that these complexes can be used as light-conversion molecular devices either in solid state or in solution.

Bejan, C.C.C. [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, Cidade Universitaria, 50670-901 Recife, CCEN-UFPE PE-Brazil (Brazil); Rocha, G.B. [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, Cidade Universitaria, 50670-901 Recife, CCEN-UFPE PE-Brazil (Brazil); Albuquerque, R.Q. [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, Cidade Universitaria, 50670-901 Recife, CCEN-UFPE PE-Brazil (Brazil); Demnitz, F.W.J. [Poseidon Pharmaceuticals A/S, 93 Pederstrupvej, 2750 Ballerup (Denmark); Sa, G.F. de [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, Cidade Universitaria, 50670-901 Recife, CCEN-UFPE PE-Brazil (Brazil); Alves, S. [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, Cidade Universitaria, 50670-901 Recife, CCEN-UFPE PE-Brazil (Brazil)]. E-mail: salvesjr@ufpe.br

2005-05-15

396

Direct synthesis of formic acid from carbon dioxide by hydrogenation in acidic media  

OpenAIRE

The chemical transformation of carbon dioxide into useful products becomes increasingly important as CO2 levels in the atmosphere continue to rise as a consequence of human activities. In this article we describe the direct hydrogenation of CO2 into formic acid using a homogeneous ruthenium catalyst, in aqueous solution and in dimethyl sulphoxide (DMSO), without any additives. In water, at 40?°C, 0.2?M formic acid can be obtained under 200?bar, however, in DMSO the same catalyst afford...

Moret, Se?verine; Dyson, Paul J.; Laurenczy, Ga?bor

2014-01-01

397

Synthesis of guanidinoacetate and creatine from amino acids by rat pancreas.  

Science.gov (United States)

Creatine is an important molecule involved in cellular energy metabolism. Creatine is spontaneously converted to creatinine at a rate of 1·7% per d; creatinine is lost in the urine. Creatine can be obtained from the diet or synthesised from endogenous amino acids via the enzymes arginine:glycine amidinotransferase (AGAT) and guanidinoacetate N-methyltransferase (GAMT). The liver has high GAMT activity and the kidney has high AGAT activity. Although the pancreas has both AGAT and GAMT activities, its possible role in creatine synthesis has not been characterised. In the present study, we examined the enzymes involved in creatine synthesis in the pancreas as well as the synthesis of guanidinoacetate (GAA) and creatine by isolated pancreatic acini. We found significant AGAT activity and somewhat lower GAMT activity in the pancreas and that pancreatic acini had measurable activities of both AGAT and GAMT and the capacity to synthesise GAA and creatine from amino acids. Creatine supplementation led to a decrease in AGAT activity in the pancreas, though it did not affect its mRNA or protein abundance. This was in contrast with the reduction of AGAT activity and mRNA and protein abundance in the kidney, suggesting that the regulatory mechanisms that control the expression of this enzyme in the pancreas are different from those in the kidney. Dietary creatine increased the concentrations of GAA, creatine and phosphocreatine in the pancreas. Unexpectedly, creatine supplementation decreased the concentrations of S-adenosylmethionine, while those of S-adenosylhomocysteine were not altered significantly. PMID:24103317

da Silva, Robin P; Clow, Kathy; Brosnan, John T; Brosnan, Margaret E

2014-02-01

398

Investigation of phospholipid synthesis and the disposition of amino acid and carbohydrate  

International Nuclear Information System (INIS)

The synthesis of pulmonary phospholipids by offspring of diabetic female rats was assessed by means of high performance liquid chromatography combined with automated phosphate analysis. No changes in the pool sizes of the major phospholipids or their precursors were observed. However, offspring of both insulin-treated and untreated diabetic mothers displayed increased pulmonary lyso-phosphatidylcholine. The concentration of glycerylphosphorylcholine, the metabolic product of lyso-phosphatidylcholine, was also increased in these offspring, providing further evidence of a reduced reacylation pathway in the offspring of diabetic mothers. The concentration of phosphatidylglycerol was reduced in the lungs from offspring of diabetic mothers. Preliminary investigation suggested that the mechanism of insulin action on lungs from offspring of diabetic rats may be the diversion of substrate from lipid synthetic pathways into protein synthesis. The utilization of [14C]-labeled amino acids and carbohydrates by normal fetal rat lung, however, revealed no direct insulin effect on protein synthesis. The ability of the fetal lung to convert amino acids into Krebs Cycle intermediates was demonstrated

399

Compromised Mitochondrial Fatty Acid Synthesis in Transgenic Mice Results in Defective Protein Lipoylation and Energy Disequilibrium  

Science.gov (United States)

A mouse model with compromised mitochondrial fatty acid synthesis has been engineered in order to assess the role of this pathway in mitochondrial function and overall health. Reduction in the expression of mitochondrial malonyl CoA-acyl carrier protein transacylase, a key enzyme in the pathway encoded by the nuclear Mcat gene, was achieved to varying extents in all examined tissues employing tamoxifen-inducible Cre-lox technology. Although affected mice consumed more food than control animals, they failed to gain weight, were less physically active, suffered from loss of white adipose tissue, reduced muscle strength, kyphosis, alopecia, hypothermia and shortened lifespan. The Mcat-deficient phenotype is attributed primarily to reduced synthesis, in several tissues, of the octanoyl precursors required for the posttranslational lipoylation of pyruvate and ?-ketoglutarate dehydrogenase complexes, resulting in diminished capacity of the citric acid cycle and disruption of energy metabolism. The presence of an alternative lipoylation pathway that utilizes exogenous free lipoate appears restricted to liver and alone is insufficient for preservation of normal energy metabolism. Thus, de novo synthesis of precursors for the protein lipoylation pathway plays a vital role in maintenance of mitochondrial function and overall vigor. PMID:23077570

Smith, Stuart; Witkowski, Andrzej; Moghul, Ayesha; Yoshinaga, Yuko; Nefedov, Michael; de Jong, Pieter; Feng, Dejiang; Fong, Loren; Tu, Yiping; Hu, Yan; Young, Stephen G.; Pham, Thomas; Cheung, Carling; Katzman, Shana M.; Brand, Martin D.; Quinlan, Casey L.; Fens, Marcel; Kuypers, Frans; Misquitta, Stephanie; Griffey, Stephen M.; Tran, Son; Gharib, Afshin; Knudsen, Jens; Hannibal-Bach, Hans Kristian; Wang, Grace; Larkin, Sandra; Thweatt, Jennifer; Pasta, Saloni

2012-01-01

400

An Efficient Synthesis of 1-Alkyl-2-phenyl-4-quinolones from 2-Halobenzoic Acids  

International Nuclear Information System (INIS)

The present method offers an efficient synthesis of 1-alkyl-2-phenyl-4-quinolones from 2-haloben-zoic acids. It has the advantages with respect to (i) synthesis of 2 equiv of alkynones 5 from 1 equiv of 4,6-pyrimidyl di(2-halobenzoates) 3, (ii) synthesis of versatile 1-alkyl-2-phenyl-4-quinolones in high overall yields, and (iii) use of readily available and cheap starting materials. Therefore, this method could be utilized as a practical synthesis of 1-alkyl-2-phenyl-4-quinolones. Several methods have been developed to synthesize 1-alkyl-2-phenyl-4-quinolones from 2'-substituted acetophenones, anilines, and 2-halobenzoyl chlorides as starting materials. The reaction of N-methylisatoic anhydride with the lithium enolate of an 4'-methoxyacetophenone afforded the 1-methyl-2-phenyl-4-quinolone in a short sequence, but the yield was low. N-(2-Acetylphenyl)benzamides, prepared by Friedel-Crafts acylation of N-phenyl benzamides with acetyl chloride or benzoylation of 2'-aminoacetophenones with benzoyl chlorides,8 were cyclized with potassium t-butoxide to yield 2-aryl-4-quinolones, which were further alkylated with alkyl iodides to give 1-alkyl-2-aryl-4-quinolones

401

An Efficient Synthesis of 1-Alkyl-2-phenyl-4-quinolones from 2-Halobenzoic Acids  

Energy Technology Data Exchange (ETDEWEB)

The present method offers an efficient synthesis of 1-alkyl-2-phenyl-4-quinolones from 2-haloben-zoic acids. It has the advantages with respect to (i) synthesis of 2 equiv of alkynones 5 from 1 equiv of 4,6-pyrimidyl di(2-halobenzoates) 3, (ii) synthesis of versatile 1-alkyl-2-phenyl-4-quinolones in high overall yields, and (iii) use of readily available and cheap starting materials. Therefore, this method could be utilized as a practical synthesis of 1-alkyl-2-phenyl-4-quinolones. Several methods have been developed to synthesize 1-alkyl-2-phenyl-4-quinolones from 2'-substituted acetophenones, anilines, and 2-halobenzoyl chlorides as starting materials. The reaction of N-methylisatoic anhydride with the lithium enolate of an 4'-methoxyacetophenone afforded the 1-methyl-2-phenyl-4-quinolone in a short sequence, but the yield was low. N-(2-Acetylphenyl)benzamides, prepared by Friedel-Crafts acylation of N-phenyl benzamides with acetyl chloride or benzoylation of 2'-aminoacetophenones with benzoyl chlorides,8 were cyclized with potassium t-butoxide to yield 2-aryl-4-quinolones, which were further alkylated with alkyl iodides to give 1-alkyl-2-aryl-4-quinolones.

Song, Yoon Ju; Choi, Jin Sun; Lee, Jae In [Duksung Women' s Univ., Seoul (Korea, Republic of)

2013-10-15

402

SYNTHESIS AND EVALUATION OF ANTHELMINTIC AND INSECTICIDAL ACTIVITIES OF 4-AMINO-ANTIPYRINE DERIVATIVES OF AMINO ACIDS AND PEPTIDES  

OpenAIRE

Antipyrine has been drawn as promising structural units in the field of medicinal and agricultural chemistry. The enzymatic synthesis of Z-L-aminoacyl-antipyrine amides from Z-protected amino acid esters and 4-aminoantipyrine (AAP) was accomplished by papain in aqueous-organic and biphasic media as well as in suspension. Hence, an attempt is made towards the synthesis of 4-Aminoantipyrine derivatives of amino acid and peptides i.e. 3-(4-antipyryl)benzoyl-amino acids/peptides) using solution p...

Himaja M; Kailash Rai; Anish K.V.; Ramana M V; Karigar A A

2012-01-01

403

One-Pot Synthesis of Novel Chiral ?-Amino Acid Derivatives by Enantioselective Mannich Reactions Catalyzed by Squaramide Cinchona Alkaloids  

Directory of Open Access Journals (Sweden)

Full Text Available An ef?cient one-pot synthesis of novel ?-amino acid derivatives containing a thiadiazole moiety was developed using a chiral squaramide cinchona alkaloid as organocatalyst. The reactions afforded chiral ?-amino acid derivatives in moderate yields and with moderate to excellent enantioselectivities. The present study demonstrated for the first time the use of a Mannich reaction catalyzed by a chiral bifunctional organocatalyst for the one-pot synthesis of novel ?-amino acid derivatives bearing a 1,3,4-thiadiazole moiety on nitrogen.

Kankan Zhang

2013-05-01

404

Amino acids attached to 2'-amino-LNA: Synthesis of DNA mixmer oligonucleotides with increased duplex stability  

DEFF Research Database (Denmark)

The synthesis of 2'-amino-LNA (locked nucleic acid) opens up exciting possibilities for modification of nucleic acids by conjugation to the 2'-nitrogen. Incorporation of unmodified and N-functionalized 2'-amino-LNA nucleotides improve duplex stability compared to unmodified DNA. 2'-Amino-LNA nucleosides derivatized with amino acids have been synthesized and incorporated into DNA oligonucleotides. Following oligonucleotide synthesis, peptides have been added using solid phase peptide coupling chem. Modification of oligonucleotides with pos. charged residues greatly improves thermal stability.

Johannsen, Marie Willaing; Wengel, Jesper

405

Monoestolides Synthesis From Ricinoleic-Oleic Acids Using Silicotungstic Acid Sol-Gel Catalyst  

Directory of Open Access Journals (Sweden)

Full Text Available Sol-gel silica-supported hydrated silicotungstic acid (STA sol-gel, prepared by incorporating hydrated silicotungstic acid (STA into silica via sol-gel technique, was used as an efficient heterogeneous catalyst for condensation reaction of a mixture ricinoleic acid (RA and oleic acid (OA. The activity and selectivity of STA sol-gel for the condensation reaction of a mixture RA and OA have been investigated and compared with unsupported STA and homogeneous perchloric acid. STA sol-gel and bulk STA catalysts surface were characterized using X-ray Photoelectron Spectroscopy (XPS analysis. The reactions were carried out under vacuum (2 mBar for 10 hours at 70 0C under solvent-less conditions. The Liquid Chromatography-Mass Spectrometry (LC-MS of reaction products results showed chromatographic peaks for the presence of three new monoestolides at retention times (tR 9.2 min (m/z 577.48, as [M-H]-, 11.2 min (m/z 559.46, [M-H]- and 12.6 min (m/z 561.48, [M-H]-. STA sol-gel catalyst is new promising heterogenous catalyst that can be used for producing estolide compounds from a mixture of RA and OA. STA sol-gel gave 100 % conversion with 60.62 % selectivity to ricinoleic-ricinoleic monoestolide acid (m/z 577.48, [M-H]-, 25.69 % selectivity to ricinoleic-linoleic monoestolide acid (m/z 559.47, [M-H]- and 13.65 % selectivity to ricinoleic-oleic monoestolide (m/z 561.48, [M-H]-.

Nor Asikin Mohamad Nordin

2011-09-01

406

Effect of penicillin on fatty acid synthesis and excretion in Streptococcus mutans BHT  

International Nuclear Information System (INIS)

Treatment of exponentially growing cultures of Streptococcus mutans BHT with growth-inhibitory concentrations (0.2 microgram/ml) of benzylpenicillin stimulates the incorporation of [2-14C] acetate into lipids excreted by the cells by as much as 69-fold, but does not change the amount of 14C incorporated into intracellular lipids. At this concentration of penicillin cellular lysis does not occur. The radioactive label is incorporated exclusively into the fatty acid moieties of the glycerolipids. During a 4-hr incubation in the presence of penicillin, the extracellular fatty acid ester concentration increases 1.5 fold, even though there is no growth or cellular lysis. An indication of the relative rate of fatty acid synthesis was most readily obtained by placing S. mutans BHT in a buffer containing 14C-acetate. Under these nongrowing conditions free fatty acids are the only lipids labeled, a factor which simplifies the assay. The addition of glycerol to the buffer causes all of the nonesterified fatty acids to be incorporated into glycerolipid. The cells excrete much of the lipid whether glycerol is present or not. Addition of penicillin to the nongrowth supporting buffer system does not stimulate the incorporation of [14C]-acetate into fatty acids

407

Synthesis of ?-amino[4-11C]butyric acid (GABA)  

International Nuclear Information System (INIS)

A one-pot synthesis of no-carrier added ?-amino[4-11C]butyric acid (GABA) starting with hydrogen [11C]cyanide prepared from [11C]carbon dioxide, is presented. Hydrogen [11C]cyanide was trapped in tetrahydrofuran/potassium hydroxide in the presence of the amino polyether Krytofix 2.2.2. A Michael addition with ethyl acrylate followed by a selective reduction and hydrolysis of the resulting amino ester gave [4-11C]GABA. The radiochemical purity of GABA was higher than 99% and the decay corrected radiochemical yield was 60-65% based on the amount of H[11C]CN used. The total synthesis time including purification was around 40 min, counted from the start of the Michael addition reaction. (Author)

408

Synthesis and characterization of copolymer hydrogels of chitosan, itaconic acid and N-isopropilacrylamide  

Directory of Open Access Journals (Sweden)

Full Text Available This paper deals with synthesis of copolymer hydrogels of N-isopropilacrylamide, itaconic acid and chitosan. During synthesis, pH of the reaction solution and temperature were varied. It was found that reaction at higher temperature, above lower critical solution temperature (LCST value of N-isopropilacrylamide resulted in a formation of polymer rich domains or aggregates in the matrix of loosely tied network, which cause a higher degree of swelling. Moreover, reaction pH also affects the degree of swelling and contraction of hydrogels owing to the different ionization of the ionic groups presence in hydrogel. The values of diffusion exponent, n, indicate non-Fickian kinetics corresponding to diffusion and relaxation of polymer chains. These hydrogels could be classified as macroporous hydrogels. Hence, it is possible to synthetize hydrogels of desired functionality which allow their application in different fields.

Milosavljevi? Nedeljko B.

2011-01-01

409

Synthesis and disappearance of cholesterol and bile acids in miniature swine  

International Nuclear Information System (INIS)

Minerature swine were fitted with indwelling cannulae at two sites in the gut and catheters in the aorta, portal vein and posterior vena cava. Radioactive acetate, alanine and glucose were administered via the duodenal cannula or the portal vein catheter and synthesis of cholesterol by gut or liver monitored via the aortic serum cholesterol specific activity. Ring labeled cholesterol was administered via jejunum and portal vein and various parameters of disappearance measured during 17 to 66 days. Conversion of cholesterol to bile acids and their subsequent disappearance from gut lumen were measured. Differences were observed in substrate preference of gut and liver and in fate of newly synthesized cholesterol. Cholesterol disappearance was found to follow a two component exponential in serum and a three component exponential in gut. Serum curves were similar to those reported for humans. Two hepatic pools of cholesterol, one accessible to lipoprotein synthesis (anabolic) and another accessible to enterohepatic circulation and 7-?-hydroxylase, were inducated

410

Cybernetic model for synthesis of poly-beta-hydroxybutyric acid in Alcaligenes eutrophus.  

Science.gov (United States)

The pathway of poly-beta-hydroxybutyric acid (PHB) exhibits a mode of transcriptional control induced by environmental stress. A new cybernetic model for coordinated regulation of stress-induced metabolism was developed to predict the growth and the synthesis of PHB in Alcaligenes eutrophus. A plausible objective for this control is optimization of acetyl-CoA utilization so that the cells have a high degree of flexibility in their catabolism. The state equation for key protein synthesis was assumed to have a dependence on the nonlinear control variable. The proposed model can demonstrate the mixed-growth-associated synythesis of PHB. Reported unstructured models were compared statistically with the result of the simulation derived from the proposed model using the experimental data of this study and the literature. The proposed model appeared to provide an excellent description for the overall fermentation range. (c) 1994 John Wiley & Sons, Inc. PMID:18615515

Yoo, S; Kim, W S

1994-05-01

411

Synthesis of the mono- and di(4-(1,1,3,3-tetramethylbutyl)) phosphoric acids  

International Nuclear Information System (INIS)

This work is related to the synthesis of organophosphorus extracting agents used in purification of heavy metals such as uranium. The mono- and di (4-(1,1,3,3- tetramethylbutyl)) phenyl phosphoric acids, respectively MOPPA and DOPPA, are synthesizd by reaction of phosphorus pentoxid with 4(1,1,3,3-tetramethylbuthyl)) phenol. the separation of MOPPA from DOPPA is realised by liquid-liquid extraction. The Characterization, carried out by infrared uv-visible spectrophotometries, ph-metry and mass spectrometry, has confirmed the identity of the synthesized products. This study also showed that the products proportions are comporable to those of the homologous products obtained with 2-ethylbexanol in the same synthesis conditions

412

Influence of gamma radiation on arachidonic acid release and prostacyclin synthesis  

International Nuclear Information System (INIS)

Cultured pulmonary artery endothelial cells produce PGI2 as their primary prostaglandin. Conditions which inhibit cell division have been shown to accelerate the synthesis of this compound. Exposure of endothelial cells to gamma radiation results in an irreversible cessation of growth and enhanced production of PGI2. The level of PGI2 measured after radiation exposure exceeds that observed in cultures rendered quiescent by serum reduction. This indicates a role for gamma radiation in the elevation of PGI2 levels which is distinct from its effect on cell division. Results presented indicate that exposure to gamma radiation does not, in and of itself, elevate PG levels but capacitates cells for enhanced production when presented with appropriate stimuli. Increased PGI2 synthesis appears to be a result of an observed increase in arachidonic acid release and an activation of cyclooxygenase

413

Engineering methylaspartate ammonia lyase for the asymmetric synthesis of unnatural amino acids  

Science.gov (United States)

The redesign of enzymes to produce catalysts for a predefined transformation remains a major challenge in protein engineering. Here, we describe the structure-based engineering of methylaspartate ammonia lyase (which in nature catalyses the conversion of 3-methylaspartate to ammonia and 2-methylfumarate) to accept a variety of substituted amines and fumarates and catalyse the asymmetric synthesis of aspartic acid derivatives. We obtained two single-active-site mutants, one exhibiting a wide nucleophile scope including structurally diverse linear and cyclic alkylamines and one with broad electrophile scope including fumarate derivatives with alkyl, aryl, alkoxy, aryloxy, alkylthio and arylthio substituents at the C2 position. Both mutants have an enlarged active site that accommodates the new substrates while retaining the high stereo- and regioselectivity of the wild-type enzyme. As an example, we demonstrate a highly enantio- and diastereoselective synthesis of threo-3-benzyloxyaspartate (an important inhibitor of neuronal excitatory glutamate transporters in the brain).

Raj, Hans; Szyma?ski, Wiktor; de Villiers, Jandré; Rozeboom, Henriëtte J.; Veetil, Vinod Puthan; Reis, Carlos R.; de Villiers, Marianne; Dekker, Frank J.; de Wildeman, Stefaan; Quax, Wim J.; Thunnissen, Andy-Mark W. H.; Feringa, Ben L.; Janssen, Dick B.; Poelarends, Gerrit J.

2012-06-01

414

Chitosan/poly (vinyl pyrollidone) coatings improve the antibacterial properties of poly(ethylene terephthalate)  

Energy Technology Data Exchange (ETDEWEB)

Chitosan/poly (vinyl pyrollidone) (CHI/PVP) coatings were prepared to improve the antibacterial properties of poly (ethylene terephthalate) (PET) by a simple dip-coating method. The binding capability of CHI/PVP coatings was enhanced by successively pretreatment of PET by polyetherimide and polyacrylic acid and crosslinking. Measurements of water contact angle and atomic force microscope revealed that the coatings created a highly hydrophilic surface with low roughness. Adherences of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) on PET with CHI/PVP coating were significantly reduced. Bactericidal activity of CHI/PVP coatings was good against E. coli and S. aureus and the adding of PVP obviously increased its antiadhesion property. In vitro cytotoxicity tests, cell morphology and activity evaluation of human umbilical vein endothelial cells showed that CHI/PVP coatings had good biocompatibility.

Wang Bailiang; Wang Jinlei; Li Dandan; Ren Kefeng [MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Ji Jian, E-mail: jijian@zju.edu.cn [MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

2012-08-01

415

Synthesis and biological evaluation of phenoxyacetic acid derivatives as novel free fatty acid receptor 1 agonists.  

Science.gov (United States)

Free fatty acid receptor 1 (FFA1) is a new potential drug target for the treatment of type 2 diabetes because of its role in amplifying glucose-stimulated insulin secretion in pancreatic ?-cell. In the present studies, we identified phenoxyacetic acid derivative (18b) as a potent FFA1 agonist (EC50=62.3 nM) based on the structure of phenylpropanoic acid derivative 4p. Moreover, compound 18b could significantly improve oral glucose tolerance in ICR mice and dose-dependently reduced glucose levels in type 2 diabetic C57BL/6 mice without observation of hypoglycemic side effect. Additionally, compound 18b exhibited acceptable PK profiles. In summary, compound 18b with ideal PK profiles exhibited good activity in vitro and in vivo, and might be a promising drug candidate for the treatment of diabetes mellitus. PMID:25481394

Wang, Xuekun; Zhao, Tianxiao; Yang, Baowei; Li, Zheng; Cui, Jian; Dai, Yuxuan; Qiu, Qianqian; Qiang, Hao; Huang, Wenlong; Qian, Hai

2015-01-01

416

Synthesis and optical resolution of the neurotoxin 2-amino-3-([15N]-methylamino)propanoic acid (BMAA)  

International Nuclear Information System (INIS)

The synthesis of 2-amino-3-([15N]-methylamino)propanoic acid (synonyms, BMAA, ?-N-mehylamino-alanine) from ?-acetamidoacrylic acid and [15N]-methylamine is described. Enantioselective hydrolysis of the acetamide group, mediated by the enzyme Acylase 1 (EC 3.5.1.14), yielded (R)-BMAA and the (S)-?-acetamido derivative. Acid hydrolysis of the latter compound yielded (S)-BMAA. (author)

417

Synthesis and optical resolution of the neurotoxin 2-amino-3-([[sup 15]N]-methylamino)propanoic acid (BMAA)  

Energy Technology Data Exchange (ETDEWEB)

The synthesis of 2-amino-3-([[sup 15]N]-methylamino)propanoic acid (synonyms, BMAA, [beta]-N-mehylamino-alanine) from [alpha]-acetamidoacrylic acid and [[sup 15]N]-methylamine is described. Enantioselective hydrolysis of the acetamide group, mediated by the enzyme Acylase 1 (EC 3.5.1.14), yielded (R)-BMAA and the (S)-[alpha]-acetamido derivative. Acid hydrolysis of the latter compound yielded (S)-BMAA. (author).

Yulin Hu; Ziffer, H. (National Inst. of Diabetes and Digestive and Kidney Diseases, Bethesda, MD (United States))

1990-05-01

418

The effect of delta-aminolevulinic acid on the synthesis and metabolism of GABA in rabbit brain homogenates  

International Nuclear Information System (INIS)

The porphyrin precursor delta-aminolevulinic acid (delta-ALA) is a structural analogue of the putative amino acid neurotransmitter, ?-aminobutyric acid (GABA). This study has demonstrated that delta-ALA has no effect on glutamate decarboxylase activity and only a small inhibitory effect on GABA aminotransferase activity. This would suggest that if accumulation of delta-ALA is related to development of the acute attack of porphyria, it is not via an effect on GABA synthesis and metabolism

419

Synthesis and coating of nanosilver by vanillic acid and its effects on Dunaliella salina Teod.  

Directory of Open Access Journals (Sweden)

Full Text Available Plant phenolics have high reducing capacity which can be exploited in the synthesis of nanomaterials. In the present study, phytoreductant vanillic acid is used to produce and coat silver nanoparticles. The effects of Ag nanoparticles on the unicellular green algae D. Salina were then investigated. Under optimum pH and temperature, silver ions were reduced to silver metal by vanillic acid. The absorption spectra of the silver nanoparticles showed a maximum band of 410 nm, which is characteristic of the surface plasmon resonance of silver nanoparticles. Dynamic light scattering (DLS showed a narrow distribution size with an average of 52 nm. High concentrations of Ag nanoparticles reduced growth, total carotenoids, chlorophyll content, phenolics and antioxidant activity of the algae. Based on these results, phytoreductant vanillic acid can be used for synthesis and coating of nanosilver. Due to the projected increase in quantities and types of nanomaterials which leads to their elevated release into the environment and also because of the toxicity of nanomaterials, an urgent need to evaluate the impacts of nano-sized particles on the environment and living organisms is felt.

Hajar Zamani

2013-09-01

420

Robust Identification of Polyethylene Terephthalate (PET) Plastics through Bayesian Decision  

OpenAIRE

Recycling is one of the most efficient methods for environmental friendly waste management. Among municipal wastes, plastics are the most common material that can be easily recycled and polyethylene terephthalate (PET) is one of its major types. PET material is used in consumer goods packaging such as drinking bottles, toiletry containers, food packaging and many more. Usually, a recycling process is tailored to a specific material for optimal purification and decontamination to obtain high g...

Zulkifley, Mohd Asyraf; Mustafa, Mohd Marzuki; Hussain, Aini; Mustapha, Aouache; Ramli, Suzaimah

2014-01-01

421

The radiation chemistry of aqueous sodium terephthalate solutions  

International Nuclear Information System (INIS)

The radiation chemistry of cobalt-60 gamma-irradiated aqueous sodium terephthalate solutions has been studied. In aerated 4 x 10-4M sodium hydroxide solutions, the main products are hydroxyterephthalate (HTA) (G = 0.99 +- 0.01), carbonate (G = 1.31 +- 0.08), and peroxides (G = 2.84 +- 0.04). The HTA and carbonate species are both formed as a result of hydroxyl radical attack and account for approximately 90 per cent of hydroxyl radical reactions. Oxygen needs to be present for efficient conversion of the terephthalate-OH radical adduct to HTA and oxygenation increases G(HTA) above the aerated solution value. G(HTA) is unaffected by changes in terephthalate concentration between 1 x 10-4M and 1 x 10-2M in sodium hydroxide solutions at pH 10. Decreasing the solution pH does however affect G(HTA). In phosphate buffered solutions pH 6.85, G(HTA) is 0.93 +- 0.01 and lower values are obtained with further decrease in solution pH. The lowering of the G(HTA) value is attributed to recombination reactions between the terephthalate-OH radical products and reducing radical products. Experimental evidence supporting the recombination postulate was obtained from the measurement of a parallel decrease in the peroxide yield and the observation of a dose rate effect on G(HTA). Competition kinetic studies with the added solutes carbonate and bicarbonate gave the rate ratios k (OH + TA2-) : k(OH + CO32-) : k(OH + HCO3-) = 1 : 0.105 : 0.0036

422

Waste polyethylene terephthalate as an aggregate in concrete  

OpenAIRE

This paper reports the strength behaviour of concrete containing three types of recycled polyethylene terephthalate (PET) aggregate. Results are also analysed to determine the PET-aggregate's effect on the relationship between the flexural and splitting tensile strengths and compressive strength and to know whether the relationships between compressive strength and other strength characteristics given in European design codes are applicable to concrete made with PET-aggregates. The compressiv...

Nabajyoti Saikia; Jorge Brito

2013-01-01

423

High Speed Deformation of the Poly(Ethylene Terephthalate)  

OpenAIRE

Mechanical behaviour of amorphous and semi-crystalline polyethylene terephthalate films is studied over five decades of strain rates, at temperatures below and above the glass transition. The data were obtained by combining measurements from conventional Instron machine with data from a high-speed tensile machine. The activation parameters are determined and compared with the activation process of the ? relaxation. Different modes of failure have been identified and the occurrence of an inte...

Ladouce, L.; Perez, J.; Vassoille, R.

1996-01-01

424

A study on nucleic acid synthesis and nuclear chromatin of uterine cervical carcinoma  

International Nuclear Information System (INIS)

1. Specimens from cervical carcinoma taken prior to radiotherapy showed mean labeling index of 29.9% for 3H-TdR and 63.4% for 3H-UdR, indicating that small cell undifferntiated type carcinoma have relatively prominent activity of nucleic acid synthesis as compared to large cell non-keratinizing or keratinizing type carcinoma. 2. Even with biopsy specimens, chromatin patterns of most unirradiated tumors were predominantly of active type whereas tumors in which degenerative patterns of chromatin predominated were only rarely encountered. Active chromatin patterns were frequently conspicuous in small cell undifferentiated type carcinoma. 3. Both the 3H-TdR and 3H-UdR labeling index of cervical carcinoma decreased following irradiation, the diminution of the former being progressively greater with increasing cumulative dosis of radiation. Small cell undifferentiated type carcinoma showed a more marked diminution of the labeling index than large cell type carcinomas. 4. Degenerative patterns of chromatin increased progressively to become predominant over active patterns, with increasing dose of radiation. This shift to predominance of degenerative patterns was more conspicuous in small cell undifferentiated type carcinoma than in large cell type carcinomas. 5. There was a noticeably close interrelation between the nucleic acid synthesis and the chromatin pattern of cervical carcinoma cells before as well as after irradiation. Hows before as well as after irradiation. However, the tumor cell responses to radiation appeared to show a slight time lag between the morphologic aspect, or nucleic acid synthesis, and the morphologic aspect, or chromatin patterns, the former preceding the latter. (J.P.N.)

425

Inhibitors of Fatty Acid Synthesis Induce PPAR?-Regulated Fatty Acid ?-Oxidative Genes: Synergistic Roles of L-FABP and Glucose  

OpenAIRE

While TOFA (acetyl CoA carboxylase inhibitor) and C75 (fatty acid synthase inhibitor) prevent lipid accumulation by inhibiting fatty acid synthesis, the mechanism of action is not simply accounted for by inhibition of the enzymes alone. Liver fatty acid binding protein (L-FABP), a mediator of long chain fatty acid signaling to peroxisome proliferator-activated receptor-? (PPAR?) in the nucleus, was found to bind TOFA and its activated CoA thioester, TOFyl-CoA, with high affinity wh...

Huang, Huan; Mcintosh, Avery L.; Martin, Gregory G.; Petrescu, Anca D.; Landrock, Kerstin K.; Landrock, Danilo; Kier, Ann B.; Schroeder, Friedhelm

2013-01-01

426

Rational design, synthesis, and pharmacological evaluation of 2-azanorbornane-3-exo,5-endo-dicarboxylic acid : a novel conformationally restricted glutamic acid analogue  

DEFF Research Database (Denmark)

The design and synthesis of conformationally restricted analogues of alpha-amino acids is an often used strategy in medicinal chemistry research. Here we present the rational design, synthesis, and pharmacological evaluation of 2-azanorbornane-3-exo,5-endo-dicarboxylic acid (1), a novel conformationally restricted (S)-glutamic acid (Glu) analogue intended as a mimic of the folded Glu conformation. The synthesis of 1 was completed in its racemic form in eight steps from commercially available starting materials. As a key step, the first facially selective hydroboration of a 5-methylidene[2.2.1]bicyclic intermediate was investigated. In this transformation, the catalytic methodology of Wilkinson's/catechol borane proved superior to stoichiometric borane or dialkyl borane reagents, in terms of higher diastereomeric excess and chemical yield. To our surprise (+/-)-1 did not show affinity in binding studies on native 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) (IC(50) > 300 microM, [(3)H]AMPA)or kainic acid (IC(50) > 160 microM, [(3)H]kainic acid) receptors nor in binding studies on the cloned iGluR5,6 subtypes (IC(50) > 300 microM, [(3)H]kainic acid).

Bunch, Lennart; Liljefors, Tommy

2003-01-01

427

Lyso(bis)phosphatidic acid: a preferred donor of arachidonic acid for macrophage-synthesis of eicosanoids  

International Nuclear Information System (INIS)

In order to dissect mechanisms of arachidonic acid (20:4) metabolism, two cell populations were investigated, resident (AM) and Bacillus Calmette-Guerin-activated (BCG-AM) rabbit alveolar macrophages. After purified AM were labeled overnight with [3H]20:4, radioactivity was localized primarily within lyso(bis)phosphatidic acid [L(bis)PA] (13.1%), phosphatidylethanolamine (PE) (22.8%) and phosphatidylcholine (PC) (26.7%), with lesser amounts recovered in phosphatidyl-serine (PS) plus phosphatidylinositol (PI) (9.2%). By contrast, analysis of the phospholipid classes from prelabeled BCG-AM revealed that the mass of L(bis)PA as well as its [3H]20:4 content was profoundly decreased while other BCG-AM phospholipids remained unchanged. When [3H]20:4-labeled AM were stimulated with 1 ?M 12-0-tetradecanoyl-phorbol-13-acetate (TPA), a loss of [3H]20:4 was observed from L(bis)PA, PE, PC, and PS/PI with a corresponding increase in eicosanoid synthesis. BCG-AM exposed to either TPA or 3.8 ?M Ca+2 ionophore A23187 liberated [3H]20:4 solely from Pe and PC. BCG-AM, which exhibited depressed eicosanoid formation, consistently failed to deacylate [3H]20:4 from L(bis)PA or PI. Their evidence suggests that the diminution of eicosanoid synthesis by BCG-AM may be due to the reduction of 20:4 contained within specific phospholipid pools, namely L(bis)PA

428

Lyso(bis)phosphatidic acid: a preferred donor of arachidonic acid for macrophage-synthesis of eicosanoids  

Energy Technology Data Exchange (ETDEWEB)

In order to dissect mechanisms of arachidonic acid (20:4) metabolism, two cell populations were investigated, resident (AM) and Bacillus Calmette-Guerin-activated (BCG-AM) rabbit alveolar macrophages. After purified AM were labeled overnight with (/sup 3/H)20:4, radioactivity was localized primarily within lyso(bis)phosphatidic acid (L(bis)PA) (13.1%), phosphatidylethanolamine (PE) (22.8%) and phosphatidylcholine (PC) (26.7%), with lesser amounts recovered in phosphatidyl-serine (PS) plus phosphatidylinositol (PI) (9.2%). By contrast, analysis of the phospholipid classes from prelabeled BCG-AM revealed that the mass of L(bis)PA as well as its (/sup 3/H)20:4 content was profoundly decreased while other BCG-AM phospholipids remained unchanged. When (/sup 3/H)20:4-labeled AM were stimulated with 1 ..mu..M 12-0-tetradecanoyl-phorbol-13-acetate (TPA), a loss of (/sup 3/H)20:4 was observed from L(bis)PA, PE, PC, and PS/PI with a corresponding increase in eicosanoid synthesis. BCG-AM exposed to either TPA or 3.8 ..mu..M Ca/sup +2/ ionophore A23187 liberated (/sup 3/H)20:4 solely from Pe and PC. BCG-AM, which exhibited depressed eicosanoid formation, consistently failed to deacylate (/sup 3/H)20:4 from L(bis)PA or PI. Their evidence suggests that the diminution of eicosanoid synthesis by BCG-AM may be due to the reduction of 20:4 contained within specific phospholipid pools, namely L(bis)PA.

Cochran, F.; Roddick, V.; Connor, J.; Waite, M.

1986-05-01

429

Asymmetric synthesis of quaternary aryl amino acid derivatives via a three-component aryne coupling reaction  

Directory of Open Access Journals (Sweden)

Full Text Available A method was developed for the synthesis of ?-alkyl, ?-aryl-bislactim ethers in good to excellent yields and high diastereoselectivities, consisting of a facile one-pot procedure in which the aryl group is introduced by means of a nucleophilic addition to benzyne and the alkyl group by alkylation of a resultant benzylic anion. Hydrolysis of the sterically less hindered adducts gave the corresponding quaternary amino acids with no racemization, whereas hydrolytic ring opening gave the corresponding valine dipeptides from bulkier bislactims.

Elizabeth P. Jones

2011-11-01

430

Synthesis of 2-(Hetero)aryl-5-(trimethylsilylethynyl)oxazoles from (Hetero)arylacrylic Acids.  

Science.gov (United States)

A three-step method for the synthesis of 2-(hetero)aryl-5-(trimethylsilylethynyl)oxazoles is described. Easily accessible bis(trimethylsilyl)acetylene and acrylic acid derivatives are used as starting materials for the preparation of mono- and disubstituted 5-(trimethylsilyl)pent-1-en-4-yn-3-ones. Oxidative phthalimidoaziridination of these enynones provides the key 2-acyl-1-phthalimidoaziridines that are further utilized in the thermal expansion of the three-membered ring to furnish the target functionalizable oxazoles. PMID:25840023

Pankova, Alena S; Stukalov, Alexander Yu; Kuznetsov, Mikhail A

2015-04-17

431

A novel synthesis of the N-13 labeled atmospheric trace gas peroxynitric acid  

International Nuclear Information System (INIS)

Radioactively labeled trace gases have been successfully used to study heterogeneous chemistry of atmospheric relevance. Here we present a new synthesis of gas-phase peroxynitric acid labeled with 13N (H13NO4) to study the interaction of HNO4 with ice and snow surfaces. A yield of about 30% for HNO4 was determined. The main by-products were HNO3 and HNO2. Exposure of an ice packed bed flow tube to these species revealed that the interaction with the surface scale in the order HNO3 > HNO4 = HNO2 > NO2. (orig.)

432

Synthesis, characterization and catalytic activity of oxovanadium (IV) complexes of heterocyclic acid hydrazones  

International Nuclear Information System (INIS)

Two acid hydrazones, Furan-2-carbaldehyde nicotinic hydrazone (L1) and Furan-2-carbaldehyde benzhydrazone (L2) have been synthesised and they are characterized by elemental analysis, IR, NMR and UV spectral analysis. Oxovanadium (IV) complexes of these two hydrazones were synthesised and characterised by elemental analysis, IR, UV, EPR, molar conductivity and magnetic susceptibility measurements. Conductivity measurements reveal that the complexes are nonelectrolytes. Spectral data indicates the square pyramidal geometry for the monomeric give coordinated oxovanadium (IV) complexes with the general formula (VO(L)(OCH3)). The complex was studied for its catalytic activity and was found to be a good catalyst in quinoxaline synthesis. (author)

433

Semi-synthesis of new antimicrobial esters from the natural oleanolic and maslinic acids.  

Science.gov (United States)

In this article, we report an effective procedure for the selective isolation of oleanolic acid 1 and maslinic acid 2 (3.4 and 8.5mg/g DW, respectively) from pomace olive (Olea europaea L.) using an ultrasonic bath, and the synthesis of a series of new triterpenic acid esters. The compounds were characterized by their spectral data and were evaluated for their antimicrobial activity. Among the compounds tested, those having sulfur and chlorine atoms were found to be antibacterial. They showed activity against two Gram-positive bacteria Staphylococcus aureus and Enterococcus faecalis and two Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa (MICs within a range of 5-25?g/mL). The fungus Penicillium italicum was found to be the most sensitive to both sulfur derivatives: (3?)-3-((thiophene-2-carbonyl)oxy)-olean-12-en-28-oic acid (1a) (IZ=22mm) and (2?,3?-2,3-bis((thiophene-2-carbonyl)oxy)olean-12-en-28-oic acid (2a) (IZ=24mm). PMID:25863603

Chouaïb, Karim; Hichri, Fayçal; Nguir, Asma; Daami-Remadi, Majda; Elie, Nicolas; Touboul, David; Ben Jannet, Hichem; Hamza, M'hamed Ali

2015-09-15

434

Expanding mesoporosity of triblock-copolymer-templated silica under weak synthesis acidity.  

Science.gov (United States)

With initial aging at low temperature for enough time, silicas with large mesoporosity were synthesized using triblock copolymer as template agent under weak acidities. SBA-15 with periodic mesostructure and short mesochannels could be synthesized at pH 2.5-3.0 within weak acidity range, and the surface areas, pore diameters and pore volumes reached up to ca. 1000m(2)/g, 8.8nm and 2.0cm(3)/g, respectively, which were significantly higher than those of the conventional SBA-15 synthesized under strong acidities. Mesoporous silica with wormhole structure and abundant textural porosity was formed at pH approximately 3.5. The increased hydrophobic volume of the copolymer micelles at elevated pH values was responsible for the enlargement of mesoporosity in the products. The materials synthesized under weak acidities showed lower hexagonal ordering in comparison to the general SBA-15 synthesized under strong acidities because the decreased hydronium ion concentration induced relatively weaker assembly forces during the synthesis. Nonetheless, the short mesochannels and large pore diameter in the products might be beneficial to some applications in which fast diffusion of molecules is required. PMID:19683247

Li, Jinjun; Hu, Qin; Tian, Hua; Ma, Chunyan; Li, Landong; Cheng, Jie; Hao, Zhengping; Qiao, Shizhang

2009-11-01

435

Synthesis of anaerobic degradation biomarkers alkyl-, aryl- and cycloalkylsuccinic acids and their mass spectral characteristics.  

Science.gov (United States)

Anaerobic biodegradation of petroleum hydrocarbons has been reported to proceed predominantly via fumarate addition to yield substituted succinate metabolites. These metabolites, commonly regarded as signature biomarkers, are specific indicators of anaero- bic hydrocarbon degradation by microbial activity. To the best of our knowledge, mass spectrometry information for 2-(1-methylalkylj succinic acids, 2-arylsuccinic acids, 2-cycloalkylsuccinic acids and/or their derivatives is still incomplete, especially for the analysis of environmental samples. Here, a novel approach is proposed for the successful synthesis of five hydrocarbon-derived succinic acids. The characteristic fragments of 2-[1-methylalkyllsuccinic acid diesters were investigated by four derivatization processes (methyl, ethyl, n-butyl and trimethylsilyl esterification], some of which are not available in official Libraries. Under electron ionization mass spec- trometry conditions, informative fragments of various molecular masses have been obtained. Results confirmed characteristic differ- ences among the derivatization processes of the chemically synthesized compounds. In the case of 2-[cyclo)alkylsuccinate esters, four intermediate fragments were observed at m/z 114 + 14n, 118 + 28n, [M - [17 + 14n1

Bian, Xin-Yu; Mbadinga, Serge Maurice; Yang, Shi-Zhong; Gu, Ji-Dong; Ye, Ru-Qiang; Mu, Bo-Zhong

2014-01-01

436

Lanthanide nitrates as Lewis acids in the one-pot synthesis of 1,2,4-oxadiazole derivatives  

Energy Technology Data Exchange (ETDEWEB)

In this work we report the use of lanthanide nitrates [Ln(NO{sub 3}){sub 3}] acting as catalyst in direct one pot synthesis of 3-benzoyl- and 3-acetyl-1,2,4-oxadiazoles derivatives from ketones, nitriles and nitric acid. This is the first example of one-pot synthesis of benzoyl- and acetyl 1,2,4-oxadiazoles derivatives preparation using acetophenones derivates with electron-donator groups. (author)

Vale, Juliana A.; Faustino, Wagner M., E-mail: julianadqf@yahoo.com.br [Departamento de Quimica, Universidade Federal da Paraiba, Joao Pessoa, PB (Brazil); Zampieri, Davila de S.; Moran, Paulo J.S.; Rodrigues, Jose A.R. [Instituto de Quimica, Universidade Estadual de Campinas, SP (Brazil); Sa, Gilberto F. de [Departamento de Quimica Fundamental, CCEN, Universidade Federal de Pernambuco, Recife, PE (Brazil)

2012-08-15

437

Lanthanide nitrates as Lewis acids in the one-pot synthesis of 1,2,4-oxadiazole derivatives  

International Nuclear Information System (INIS)

In this work we report the use of lanthanide nitrates [Ln(NO3)3] acting as catalyst in direct one pot synthesis of 3-benzoyl- and 3-acetyl-1,2,4-oxadiazoles derivatives from ketones, nitriles and nitric acid. This is the first example of one-pot synthesis of benzoyl- and acetyl 1,2,4-oxadiazoles derivatives preparation using acetophenones derivates with electron-donator groups. (author)

438

An easy and direct method for the synthesis of 1,2,4-triazole derivatives through carboxylic acids and hydrazinophthalazine  

Directory of Open Access Journals (Sweden)

Full Text Available We have developed an easy method for the synthesis of thirteen compounds derived from 1,2,4-triazoles through a carboxylic acid and hydrazinophthalazine reaction, with a 75-85% yield mediated by the use of agents such as 1-ethyl-3-(3'-dimethylaminopropyl-carbodiimide hydrochloride and 1-hydroxybenzotriazole. The operational simplicity of this method and the good yield of products make it valuable for the synthesis of new compounds with pharmacological activity.

Gildardo Rivera

2008-01-01

439

A urinary metabolite of ?1-tetrahydrocannabinol. The first synthesis of 4''-hydroxy-?1-tetrahydrocannabinol-7-oic acid labelled with deuterium  

International Nuclear Information System (INIS)

The first synthesis of 4''-hydroxy-?-1-THC-7-oic acid, one of the three major metabolites of ?1-THC identified in human urine is discussed. Methyl 4-(3,5-dihydroxyphenyl)butanoate was prepared from 3,5-diydroxybenzoic acid in an overall yield of 15% was condensed with a terpene synthon under acidic conditions followed by hydrolysis and conversion of the 4''-carboxylic acid function to the corresponding methyl ketone using methyllithium. Reduction with NaBH4 afforded the secondary alcohol in the side-chain. Acetylation and removal of the 1,3-dithiane masking group gave the aldehyde in C-7-position which was further oxidized using NaClO2 followed by deacetylation to give the desired metabolite. The same procedure may be used for the synthesis of unlabelled 4''-hydroxy-?1-THC-7-oic acid. (author)

440

Bed rest impairs skeletal muscle amino acid transporter expression, mTORC1 signaling, and protein synthesis in response to essential amino acids in older adults  

OpenAIRE

Skeletal muscle atrophy during bed rest is attributed, at least in part, to slower basal muscle protein synthesis (MPS). Essential amino acids (EAA) stimulate mammalian target of rapamycin (mTORC1) signaling, amino acid transporter expression, and MPS and are necessary for muscle mass maintenance, but there are no data on the effect of inactivity on this anabolic mechanism. We hypothesized that bed rest decreases muscle mass in older adults by blunting the EAA stimulation of MPS through reduc...

Drummond, Micah J.; Dickinson, Jared M.; Fry, Christopher S.; Walker, Dillon K.; Gundermann, David M.; Reidy, Paul T.; Timmerman, Kyle L.; Markofski, Melissa M.; Paddon-jones, Douglas; Rasmussen, Blake B.; Volpi, Elena

2012-01-01

441

A new and concise strategy to the enantioselective synthesis of (S)-2-amino-4-oxo-4-(pyridine-2-yl) butanoic acid from aspartic acid  

Energy Technology Data Exchange (ETDEWEB)

The alpha-amino acid (S)-5 was synthesized using in the key step a chemoselective nucleophilic substitution between a diester derived from L-aspartic acid and 2-lithium pyridine. The overall yield (13%, 5 steps) was similar to those previously described by our group for the R isomer (the first exogen full agonist of the NMDA receptors) from D-mannitol (12%, 10 steps) and by Lovey and Copper for the racemic synthesis (17%, 5 steps). (author)

Lima, Evanoel Crizanto de; Souza, Carolina C. de; Maior, Marta C.L.S.; Costa, Paulo R.R., E-mail: prrcosta@ism.com.b [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Centro de Ciencias da Saude. Nucleo de Pesquisas de Produtos Naturais; Lima, Paulo G. de [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Quimica; Dias, Ayres G. [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Inst. de Quimica

2010-07-01

442

Toxicological characterization of phthalic Acid.  

Science.gov (United States)

There has been growing concern about the toxicity of phthalate esters. Phthalate esters are being used widely for the production of perfume, nail varnish, hairsprays and other personal/cosmetic uses. Recently, exposure to phthalates has been assessed by analyzing urine for their metabolites. The parent phthalate is rapidly metabolized to its monoester (the active metabolite) and also glucuronidated, then excreted. The objective of this study is to evaluate the toxicity of phthalic acid (PA), which is the final common metabolic form of phthalic acid esters (PAEs). The individual PA isomers are extensively employed in the synthesis of synthetic agents, for example isophthalic acid (IPA), and terephthalic acid (TPA), which have very broad applications in the preparation of phthalate ester plasticizers and components of polyester fiber, film and fabricated items. There is a broad potential for exposure by industrial workers during the manufacturing process and by the general public (via vehicle exhausts, consumer products, etc). This review suggests that PA shows in vitro and in vivo toxicity (mutagenicity, developmental toxicity, reproductive toxicity, etc.). In addition, PA seems to be a useful biomarker for multiple exposure to PAEs in humans. PMID:24278572

Bang, Du Yeon; Lee, In Kyung; Lee, Byung-Mu

2011-12-01

443

Evidence for transport intermediates in aromatic amino acid synthesis of non-green tissues  

International Nuclear Information System (INIS)

Quinate (QA) is the predominant pre-aromatic compound formed at high rates in leaves of many plants at the early vegetation stage and transported through the phloem. The transfer of 3-dehydroquinate, 3-dehydroshikimate and (SkA) across the plastidial membranes has been evidenced. The question was whether the rate of QA uptake is comparable to that of the 3 SkA-pathway intermediates. To demonstrate this, /U-14C/QA and /U-14C/SkA were applied to Brassica rapa roots. Both compounds were uptaken at considerable rates and incorporated into aromatic amino acids (Phe + Tyr + Trp formation, in nmol/g fresh wt x h: applying 145 ?mol QA: 21.2; applying 156 ?mol Ska: 31.8). Thus, QA is a possible candidate for transport into non-green tissues for aromatic amino acid synthesis

444

Origin of fatty acid synthesis - Thermodynamics and kinetics of reaction pathways  

Science.gov (United States)

The primitiveness of contemporary fatty acid biosynthesis was evaluated by using the thermodynamics and kinetics of its component reactions to estimate the extent of its dependence on powerful and selective catalysis by enzymes. Since this analysis indicated that the modern pathway is not primitive because it requires sophisticated enzymatic catalysis, an alternative pathway of primitive fatty acid synthesis is proposed that uses glycolaldehyde as a substrate. In contrast to the modern pathway, this primitive pathway is not dependent on an exogenous source of phosphoanhydride energy. Furthermore, the chemical spontaneity of its reactions suggests that it could have been readily catalyzed by the rudimentary biocatalysts available at an early stage in the origin of life.

Weber, Arthur L.

1991-01-01

445

Synthesis of 2, 4-- dichloro phenoxy acetic acid [ Carboxy- 14 C] as herbicide  

International Nuclear Information System (INIS)

One of the important herbicide, that can be used for the practical mechanism investigations and studies of metabolism functions of different plants is 2,4 dichlorophenoxy acetic acid compound. In this article, the production method for labeling the titled compound is explained. At the first stage of this research work, barium[14C] carbonate is converted into potassium [14C] by using potassium azid at a reasonable temperature. Then, after a few synthesis reaction, the compound 2,4 dichlorophenoxy methyl iodide is produced via 2,4 dichlorophenoxy as a starting material. At the next stage, the real material as a herbicide: 2,4 dichlorophenoxy acetic acid [carboxy- 14C] is prepared and produced, by the coupling reaction between 2,4 dichlorophenoxy methyl iodide and potassium [14C] cyanide, and then the resulting nitrile has been hydrolyzed

446

Convenient Synthesis and Antimicrobial Activity of Some Novel Amino Acid Coupled Triazoles  

Directory of Open Access Journals (Sweden)

Full Text Available This study describes a promising one-pot synthesis of [2-(5-benzyl-4-phenyl-4H-[1,2,4]triazol-3-thio-acetyl]-amino acid methyl esters 6a-h and dipeptides 10a-e, which were successfully synthesized starting from amino acid esters 5a-h, 9a-e and azides 4, 8a,b, respectively. On the other hand, azide 4 underwent Curtius rearrangement to the corresponding isocyanate, which subsequently reacted with selected aliphatic amine and/or aniline derivatives to give the corresponding urea derivatives 11 and 12a,b. Reactions of the isocyanate with secondary amines gave amide derivatives 13a,b. The structural elucidation of products is reported and some of the products were also screened for their antimicrobial activity.

S. M. El Rayes

2010-09-01

447

Summarization on the synthesis and radionuclide-labeling of peptide nucleic acid for an oligonucleotide analogue  

International Nuclear Information System (INIS)

Peptide nucleic acid (PNA), which is one kind of antisense nucleic acid compounds and an oligonucleotide analogue that binds strongly to DNA and RNA in a sequence specific manner, has its unique advantages in the field of molecular diagnostics and treatment of diseases. Now, people gradually attach more importance to PNA. To optimize the application of PNA in genetic re- search and therapy, a great number of backbone modifications on the newly- type structures of PNA were synthesized to improve its physicochemical proper- ties, such as hybridization speciality, solubility in biofluid, or cell permeability. The modified PNA labeled with radionuclides, which can obtain the aim at specific target and minimal non-target trauma, has important role in research and application of tumorous genitherapy. Here a review on the basic synthesis idea and several primary synthetic methods of PNA analogs was given, and also correlative studies and expectation on the compounds belonging to PNA series labeled with radionuclides were included. (authors)