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

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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.

2014-01-01

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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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Poly (ethylene terephthalate synthesis with catalysts derived from chrysotile asbestos  

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

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

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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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Chemical Recycling of Pop Bottles: The Synthesis of Dibenzyl Terephthalate from the Plastic Polyethylene Terephthalate  

Science.gov (United States)

A laboratory procedure involving the chemical recycling of the plastic polyethylene terephthalate (PET or PETE) from 2-L pop bottles is described. A transesterification reaction is employed to depolymerize PET. At atmospheric pressure in refluxing benzyl alcohol in the presence of a catalyst, PET is converted to dibenzyl terephthalate in moderate yields. This procedure models an industrial process that involves the transesterification reaction of PET with methanol at high temperature and pressure, conditions not normally accessible in an undergraduate laboratory, to yield dimethyl terephthalate and ethylene glycol. A second method of preparing dibenzyl terephthalate starting with terephthaloyl chloride is also described. The diester from these two approaches is characterized using melting points, TLC, and IR and NMR spectroscopy. This experiment has been used in a general chemistry sequence that has sections on organic chemistry and polymer chemistry, but is also well suited for an introductory organic chemistry laboratory course or a polymer chemistry laboratory course. This lab experiment is part of a larger effort to develop a general chemistry sequence for engineering students using the theme of chemistry and the automobile. Student results are presented.

Donahue, Craig J.; Exline, Jennifer A.; Warner, Cynthia

2003-01-01

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4,4?-Bipyridine–terephthalic acid (1/1  

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Full Text Available The asymmetric unit of the title compound, C10H8N2·C8H6O4, consists of one half-molecule of each moiety, 4,4?-bipyridine (bpy and terephthalic acid (bdc, both being located on crystallographic inversion centers. They are linked together via strong intermolecular O—H...N hydrogen bonds, forming infinite chains propagating along [1-21]. The chains are further connected through C—H...O interactions giving sheets in (012. The sheets are linked via ?–? interactions between the bpy rings and the bdc–bpy rings [centroid–centroid distances = 3.690?(2 and 3.869?(2?Å], resulting in the formation of a three-dimensional supramolecular layer-like structure.

Vandavasi Koteswara Rao

2012-06-01

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High rate treatment of terephthalic acid production wastewater in a two-stage anaerobic bioreactor.  

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The feasibility was studied of anaerobic treatment of wastewater generated during purified terephthalic acid (PTA) production in two-stage upflow anaerobic sludge blanket (UASB) reactor system. The artificial influent of the system contained the main organic substrates of PTA-wastewater: acetate, benzoate, and terephthalate. Three parallel operated reactors were used for the second stage, and seeded with a suspended terephthalate degrading culture, with and without additional methanogenic granular sludge (two different types). The first stage UASB-reactor was seeded with methanogenic granular sludge. Reactors were operated at 37 degrees C and pH 7. During the first 300 days of operation a clear distinction between the biomass grown in both reactor stages was obtained. In the first stage, acetate and benzoate were degraded at a volumetric loading rate of 40 g-COD/L . day at a COD-removal efficiency of 95% within the first 25 days of operation. No degradation of terephthalate was obtained in the first stage during the first 300 days of operation despite operation of the reactor at a decreased volumetric loading rate with acetate and benzoate of 9 g-COD/L . day from day 150. Batch incubation of biomass from the reactor with terephthalate showed that the lag-phase prior to terephthalate degradation remained largely unchanged, indicating that no net growth of terephthalate degrading biomass occurred in the first stage reactor. From day 300, however, terephthalate degradation was observed in the first stage, and the biomass in this reactor could successfully be enriched with terephthalate degrading biomass, resulting in terephthalate removal capacities of 15 g-COD/L . day. Even though no single reason could be identified why (suddenly) terephthalate degradation was obtained after such a long period of operation, it is suggested that the solid retention time as well the prevailing reactor concentrations acetate and benzoate may have played an important role. From day 1 of operation, terephthalate was degraded in the second stage. In presence of methanogenic granular biomass, high terephthalate removal capacities were obtained in these reactors (15 g-COD/L . day) after approximately 125 days of operation. From the results obtained it is concluded that terephthalate degradation is the bottleneck during anaerobic treatment of PTA-wastewater. Pre-removal of acetate and benzoate in staged bioreactor reduces the lag-phase prior to terephthalate degradation in latter stages, and enables high rate treatment of PTA-wastewater. PMID:15889396

Kleerebezem, Robbert; Beckers, Judith; Hulshoff Pol, Look W; Lettinga, Gatze

2005-07-20

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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

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

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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, monos...

Dyah Anitasari; Agus Salim; Crys Fajar Partana; Suwardi

2005-01-01

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Rapid determination of terephthalic acid in the hydrothermal decomposition product of poly(ethylene terephthalate) by thermochemolysis-gas chromatography in the presence of tetramethylammonium acetate.  

Science.gov (United States)

Thermochemolysis-gas chromatography in the presence of tetramethylammonium acetate was applied to the direct determination of terephthalic acid (TPA) contained in solid decomposition products obtained from the hydrothermal recycling process of poly(ethylene terephthalate) (PET). On the chromatograms of the hydrothermal decomposition products of PET, a sharp peak of the TPA component was clearly observed as its corresponding dimethyl ester formed through the thermochemolysis reaction. Based on the peak intensities, the contents of TPA in the decomposition products were determined precisely and rapidly without using any cumbersome sample pretreatments. PMID:21985932

Ishida, Yasuyuki; Ohsugi, Kei; Taniguchi, Kohei; Ohtani, Hajime

2011-01-01

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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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Preparation of polymer blends from glycerol, fumaric acid and of poly(ethylene terephthalate) (PET) recycled  

International Nuclear Information System (INIS)

Polymer blends based on recycled poly(ethylene terephthalate) (PET) and poly(glycerol fumarate) polyesters were prepared in different PET concentrations. The PET powder was dispersed during the poly(glycerol fumarate) synthesis at 260 deg C. The resulting blends were characterized by X-ray diffraction. The thermal stability of the materials was evaluated by thermogravimetric analysis and differential scanning calorimetry. The morphology was studies by scanning electron microscopy. The blends were clearly immiscible. The possibility of (interfacial) compatibilization of the PET domains, caused by transesterification reactions between PET and glycerol were discussed. (author)

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Biodegradability enhancement of purified terephthalic acid wastewater by coagulation-flocculation process as pretreatment.  

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In this work, the coagulation-flocculation process was used as pretreatment for purified terephthalic acid (PTA) wastewater with the objective of improving its overall biodegradability. PTA production generates wastewaters with toxicants p-xylene [1,4-dimethyl-benzene (C8H10)], a major raw material used in the production process, along with some of the intermediates, viz., p-toluic acid, benzoic acid, 4-carboxybenzaldehyde, phthalic acid and terephthalic acid. These compounds affect the bio-oxidation process of wastewater treatment; hence removal of these constituents is necessary, prior to conventional aerobic treatment. This paper addresses the application of coagulation-flocculation process using chemical coagulants, viz., aluminium sulphate (alum), polyaluminium chloride (PAC), ferrous sulphate and ferric chloride in combination with anionic polyelectrolyte. Polyaluminium chloride (PAC) in conjunction with lime and polyelectrolyte removed about 63.1% chemical oxygen demand (COD) and 45.2% biochemical oxygen demand (BOD) from PTA wastewater. Coagulation-flocculation process coupled with aerobic bio-oxidation treatment of PTA wastewater achieved, COD & BOD removals of 97.4% and 99.4%, respectively. The biodegradability enhancement evaluated in terms of the BOD5/COD ratio, increased from 0.45 to 0.67 at the optimum conditions. The results obtained from these studies indicate that the coagulation-flocculation process could be a suitable pretreatment method in reducing toxicity of PTA wastewater whilst enhancing biodegradability for aerobic biological treatment scheme. PMID:18054427

Karthik, Manikavasagam; Dafale, Nishant; Pathe, Pradyumna; Nandy, Tapas

2008-06-15

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1,4-Bis(imidazol-1-ylbenzene–terephthalic acid (1/1  

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Full Text Available In the title compound, C12H10N4·C8H6O4, 1,4-bis(imidazol-1-ylbenzene and terephthalic acid molecules are joined via strong O—H...N hydrogen bonds to form infinite zigzag chains. Both molecules are located on crystallographic inversion centers. The O—H...N hydrogen-bonded chains are assembled into two-dimensional layers through weak C—H...O and strong ?–? stacking interactions [centroid–centroid distance = 3.818?(2?Å], leading to the formation of a three-dimensional supramolecular structure.

Yurong Tang

2009-01-01

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Adsorption behavior of terephthalic acid on Au(1 0 0), Au(1 1 1) and Au(1 1 0) electrodes in neutral solution  

International Nuclear Information System (INIS)

Adsorption of terephthalic acid on Au(1 0 0), Au(1 1 1) and Au(1 1 0) electrodes in neutral solution has been investigated using in situ Fourier transform infrared (FT-IR) spectroscopy, differential capacity measurements and scanning tunneling microscopy (STM). At negative potentials, the terephthalate anions in solution adsorb in a flat orientation onto the electrode via the ? electrons of the aromatic ring. At positive potentials, the terephthalate anions adsorb in a vertical orientation via the oxygen atoms of one of the carboxyl groups as a form of dianion. At more positive potentials, the anions adsorb in a vertical orientation as a form of hydrogen terephthalate. For the three electrodes examined, the overtone and/or combination bands, due to vertically oriented hydrogen terephthalate, were observed at 2642 and 2517 cm-1, respectively. For the Au(1 1 1) electrode, STM observations indicated a flat orientation in the form of terephthalic acid

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Effect of oral administration of terephthalic acid on testicular functions of rats  

International Nuclear Information System (INIS)

To investigate the toxic effect of terephthalic acid (TPA) on testicular functions of rats, male Sprague-Dawley rats were orally administered TPA in diet at the levels 0 (control), 0.2, 1 and 5% for 90 days. Testicular functions were assessed by histopathology, testicular sperm head counts, daily sperm production, sperm motility (measured by computer-assisted sperm analysis, CASA), biochemical indices (marker testicular enzymes), and serum testosterone. Oral feeding with terephthalic acid did not cause body and testes weight loss in TPA-treated groups. Histopathologically, damages of spermatogenic cells and Sertoli cells were observed by electron microscope, testicular sperm head counts, daily sperm production, and activities of sorbitol dehydrogenase (SDH) were decreased significantly in the 5% TPA group. The motility of spermatozoa was reduced significantly in all treated groups, which was correlated with administration doses. Serum testosterone concentrations were not declined in treated groups. In conclusion, TPA can cause impairment of testicular functions. The primary sites of action may be spermatogenic cells and Sertoli cells. The results of the present study provide first information of TPA on testicular functions in male rats

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First layer compression and transition to standing second layer of terephthalic acid on Cu(100).  

Science.gov (United States)

Terephthalic acid on metal surfaces is a system of high interest for interfacial layers as well as for use in generating surface nanostructures by supramolecular self-assembly. Here we demonstrate structural transitions upon compression of the first layer as well as a significant transition from a flat lying chemisorbed first monolayer to a standing second layer. The second layer structure is stable at 150 °C, but a weakly bound state is observed to desorb molecularly below that temperature, likely a transient mobile state during annealing. Molecular resolution scanning tunnelling microscopy is complemented by X-ray photoelectron spectroscopy and thermal desorption spectroscopy in this study. These results provide general insight in the development of self-assembled organic thin films at surfaces, especially with regard to the nature of the metal/organic interface and growth transitions to maximize first layer packing and obtain a second layer that bridges commensurability with the substrate and a more bulk-like structure. PMID:22546738

Tait, Steven L; Lim, Hyuna; Theertham, Arjun; Seidel, Peter

2012-06-14

 
 
 
 
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Ultrafiltration membranes from waste polyethylene terephthalate and additives: synthesis and characterization  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The synthesis and characterization of asymmetric ultrafiltration membranes from recycled polyethylene terephthalate (PET) and polyvinylpyrrolidone (PVP) is reported. PET is currently used in many applications, including the manufacture of bottles and tableware. Monomer extraction from waste PET is e [...] xpensive, and this process has not yet been successfully demonstrated on a viable scale. Hence, any method to recycle or regenerate PET once it has been used is of significant importance from scientific and environmental research viewpoints. Such a process would be a green alternative due to reduced raw monomer consumption and the additional benefit of reduced manufacturing costs. The membranes described here were prepared by a phase-inversion process, which involved casting a solution containing PET, m-cresol as solvent, and polyethylene glycol (PEG) of different molecular weights as additives. The membranes were characterized in terms of pure water permeability (PWP), molecular weight cut-off (MWCO), and flux and membrane morphology. The results show that the addition of PEG with high molecular weights leads to membranes with higher PWP. The presence of additives affects surface roughness and membrane morphology.

Smitha, Rajesh; Zagabathuni Venkata Panchakshari, Murthy.

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Assessing human exposure to phthalic acid and phthalate esters from mineral water stored in polyethylene terephthalate and glass bottles  

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Abstract Abstract. Phthalic acid and phthalates esters present a growing interest due to a large use and to their potential toxicity. Polyethylene terephthalate (PET) and glass are both widely used materials for the bottling of drinking water. In this study, phthalic acid (PhA), bis(2-ethylhexyl) phthalate (DEHP), dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DiisoBP) and dibutyl phthalate (DBP) were analyzed in a large pool of Italian bottled water sampl...

2008-01-01

23

Kinetic evaluation and process performance of an upflow anaerobic filter reactor degrading terephthalic acid.  

Science.gov (United States)

The anaerobic degradation of terephthalic acid (TA) as the sole organic carbon source was studied in an upflow anaerobic filter (UAF) reactor. The reactor was seeded with biomass obtained from a full-scale upflow anaerobic sludge bed (UASB) reactor and was used to treat wastewater from a petrochemical facility producing dimethyl terephthalate. The UAF reactor was operated for 252 d with a constant hydraulic retention time of 24 h, and the organic loading rate (OLR) was gradually increased from 1 to 10 g-chemical oxygen demand (COD)/L d. After a lag period of approximately 40 d, the COD removal efficiency increased exponentially and high removal rate values (?90%) were obtained, except for at highest OLR (10 g-COD/L d). The high removal rates and the robustness of the reactor performance could be attributed to the formation of biofilm as well as granular sludge. The methane production rates (0.22 to 2.15 L/d) correlated well with the removed OLRs (0.3 to 6.8 g-COD/L d) during the various phases of treatment, indicating that the main mechanism of TA degradation occurs via methanogenic reactions. The average methane content of the produced biogas was 70.3%. The modified Stover-Kincannon model was found to be applicable for the anaerobic degradation of TA in UAFs (Umax = 64.5, KB = 69.1 g-COD/L d and Ymax = 0.27 L-CH4/g-CODremoved). These results suggest that UAF reactors are among the most effective reactor configurations for the anaerobic degradation of TA. PMID:24960022

Davutluoglu, Orkun I; Seckin, Galip

2014-01-01

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

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Full Text Available 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 batches of CTA and four batches of PTA as determined by the proposed CE methodology were in agreement with the results from gas chromatography and polarography methods in current use in Tereftalatos Mexicanos S.A. (TEMEX. Levels of BZ were determined only by the CE methodology and ranged from 60 - 300 ppm in CTA and 5 - 7 ppm in PTA. Several impurities deriving from the incomplete oxidation of p-xylene were investigated. So far the positive identification of 4-hydroxymethylbenzoic acid was accomplished by comparison with pure standards.

Moraes Maria de Lourdes L.

2004-01-01

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The induction of bladder stones by terephthalic acid, dimethyl terephthalate, and melamine (2,4,6-triamino-s-triazine) and its relevance to risk assessment.  

Science.gov (United States)

Terephthalic acid (TPA), dimethyl terephthalate (DMT), and melamine (MA) induced calculi and transitional cell hyperplasia in urinary bladders of rats. A high incidence of calculi was induced in weanling rats, but the incidence was much lower in adult rats ingesting the same dietary concentration of the chemical. The dose-response curves for the induction of urolithiasis in weanling rats were extremely steep, consistent with the fact that the formation calculi can occur in urine that is supersaturated, but not in urine that is undersaturated with respect to the stone components. In the cases of TPA and DMT, stones were composed primarily of calcium terephthalate (CaTPA). By determining the solubility of CaTPA, the concentration of TPA that would be required to achieve urinary saturation was calculated, and a conservative estimate of the amount of TPA or DMT that would have to be absorbed in order to induce calculi was derived. TPA and MA induced bladder tumors in rats in chronic feeding studies. However, it is likely that these tumors were secondary to the development of calculi. TPA and MA are apparently nongenotoxic, and they do not appear to be metabolized. Increased cell replication in the urothelium of the bladder caused by chronic physical injury was probably a major factor in the mechanism of induction of bladder tumors by bladder stones. Bladder neoplasms occurred primarily in the high dose groups, and they were usually, although not invariably, associated with stones. The possibility that stones were passed or were lost during processing of tissues for histopathologic examination could explain the absence of calculi from some of the neoplastic bladders. The formation of bladder calculi is an example of a threshold effect. Although there is strong evidence linking bladder stones with the induction of tumors, the existence of thresholds in chemical carcinogenesis continues to be controversial. A decision by the U.S. Environmental Protection Agency concerning the levels of MA allowed to occur in the food chain indicates that data regarding thresholds, even in the case of urolithiasis, are not being utilized in the risk assessment process. PMID:3903881

Heck, H D; Tyl, R W

1985-09-01

26

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

27

Terephthalic acid–2,2?-dimethyl-1,1?-(butane-1,4-diyldibenzimidazole (2/3  

Directory of Open Access Journals (Sweden)

Full Text Available In the crystal structure of the title compound, 2C8H6O4·3C20H22N4, there are three independent 2,2?-dimethyl-1,1?-(butane-1,4-diyldibenzimidazole molecules, each of which lies on an inversion centre. The terephthalic acid molecules are linked to adjacent 2,2?-dimethyl-1,1?-(butane-1,4-diyldibenzimidazole molecules via O—H...N hydrogen bonds.

Xian-Wu Dong

2008-05-01

28

The selective recycling of mixed plastic waste of polylactic acid and polyethylene terephthalate by control of process conditions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The glycolysis of postconsumer polyethylene terephthalate (PET) waste was evaluated with catalysts of zinc acetate, zinc stearate and zinc sulfate, showing that zinc acetate was the most soluble and effective. The chemical recycling by solvolysis of polylactic acid (PLA) and PET waste in either methanol or ethanol was investigated. Zinc acetate as a catalyst was found to be necessary to yield an effective depolymerization of waste PLA giving lactate esters, while with the same reaction condit...

Carne? Sa?nchez, Arnau; Collinson, Simon R.

2011-01-01

29

Investigation of hydrogen bonds properties in the terephthalic acid crystal, using molecular dynamics method.  

Science.gov (United States)

The aim of this study was to perform calculations using the method of Car-Parrinello molecular dynamics, leading to the optimized geometry of the molecules of 1,4-benzenedicarboxylic acid (terephthalic acid) in crystals, for the hydrogen form and three variants of substitution of deuterium atoms inside a carboxyl group. Based on the results, trajectories and dipole moments were calculated, what makes possible to simulate vibrations in different systems, and to make calculation of theoretical infrared spectra and atomic power spectra. Theoretical results were compared with the experimental spectra, which verifies the correctness of the method and also was compared with the results obtained by quantum-mechanical calculations using DFT for the isolated dimer. Comparison of the spectra of different forms, allowed for in-depth analysis of the effect of isotopic substitution on the frequency of vibrations and shapes of bands, and confirm the presence of possible coupling effects and intra- and intermolecular interactions. Comparison with the DFT results for the dimer show influence of the crystal structure on the spectra. PMID:24813277

Wierzbicka, Ewa; Boczar, Marek; Wójcik, Marek J

2014-09-15

30

Catalytic Synthesis Lactobionic Acid  

Directory of Open Access Journals (Sweden)

Full Text Available Gold nanoparticles are obtained, characterized and deposited on the carrier. Conducted catalytic synthesis of lactobionic acid from lactose. Received lactobionic acid identify on the IR spectrum.

V.G. Borodina

2014-07-01

31

In situ energy-dispersive X-ray diffraction for the synthesis optimization and scale-up of the porous zirconium terephthalate UiO-66.  

Science.gov (United States)

The synthesis optimization and scale-up of the benchmarked microporous zirconium terephthalate UiO-66(Zr) were investigated by evaluating the impact of several parameters (zirconium precursors, acidic conditions, addition of water, and temperature) over the kinetics of crystallization by time-resolved in situ energy-dispersive X-ray diffraction. Both the addition of hydrochloric acid and water were found to speed up the reaction. The use of the less acidic ZrOCl2·8H2O as the precursor seemed to be a suitable alternative to ZrCl4·xH2O, avoiding possible reproducibility issues as a consequence of the high hygroscopic character of ZrCl4. ZrOCl2·8H2O allowed the formation of smaller good quality UiO-66(Zr) submicronic particles, paving the way for their use within the nanotechnology domain, in addition to higher reaction yields, which makes this synthesis route suitable for the preparation of UiO-66(Zr) at a larger scale. In a final step, UiO-66(Zr) was prepared using conventional reflux conditions at the 0.5 kg scale, leading to a rather high space-time yield of 490 kg m(-3) day(-1), while keeping physicochemical properties similar to those obtained from smaller scale solvothermally prepared batches. PMID:24527942

Ragon, Florence; Horcajada, Patricia; Chevreau, Hubert; Hwang, Young Kyu; Lee, U-Hwang; Miller, Stuart R; Devic, Thomas; Chang, Jong-San; Serre, Christian

2014-03-01

32

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Neste trabalho, foi desenvolvido um método simples e rápido, utilizando eletroforese capilar (CE), para a análise simultânea de 4-carboxibenzaldeído (4-CBA), ácido p-toluóico (pTOL) e ácido benzóico (BZ), em lotes industriais de ácido tereftálico cru (CTA) e purificado (PTA). As condições eletroforé [...] ticas de análise foram: tampão tetraborato a 20 mmol L-1 (pH 9), injeção hidrodinâmica (5 s, 17 kPa), tensão aplicada de +30 kV e detecção direta em 200 nm. Foram analisados cinco lotes de CTA e quatro lotes de PTA nos teores de 4-CBA e pTOL pela metodologia proposta e as metodologias utilizadas na empresa Tereftalatos Mexicanos S.A. (TEMEX), que são cromatografia gasosa para pTOL e polarografia para 4-CBA, mostrando concordância entre os valores encontrados. Os níveis de BZ foram determinados apenas pela metodologia CE, apresentando no CTA, valores compreendidos entre 60 e 300 ppm, enquanto que no PTA, 5 a 7 ppm. Várias impurezas derivadas da oxidação incompleta do p-xileno foram investigadas, constatando-se a presença do ácido 4-hidroximetilbenzóico por comparação com padrões. Abstract in english 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 c [...] omprise: 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 batches of CTA and four batches of PTA as determined by the proposed CE methodology were in agreement with the results from gas chromatography and polarography methods in current use in Tereftalatos Mexicanos S.A. (TEMEX). Levels of BZ were determined only by the CE methodology and ranged from 60 - 300 ppm in CTA and 5 - 7 ppm in PTA. Several impurities deriving from the incomplete oxidation of p-xylene were investigated. So far the positive identification of 4-hydroxymethylbenzoic acid was accomplished by comparison with pure standards.

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

2004-06-01

33

Biohydrogen production from purified terephthalic acid (PTA) processing wastewater by anaerobic fermentation using mixed microbial communities  

Energy Technology Data Exchange (ETDEWEB)

Purified terephthalic acid (PTA) processing wastewater was evaluated as a fermentable substrate for hydrogen (H{sub 2}) production with simultaneous wastewater treatment by dark-fermentation process in a continuous stirred-tank reactor (CSTR) with selectively enriched acidogenic mixed consortia under continuous flow condition in this paper. The inoculated sludge used in the reactor was excess sludge taken from a second settling tank in a local wastewater treatment plant. Under the conditions of the inoculants not less than 6.3 gVSS/L, the organic loading rate (OLR) of 16 kgCOD/m{sup 3} d, hydraulic retention time (HRT) of 6 h and temperature of (35 {+-} 1) C, when the pH value, alkalinity and oxidation-reduction potential (ORP) of the effluent ranged from 4.2 to 4.4, 280 to 350 mg CaCO{sub 3}/L, and -220 to -250 mV respectively, soluble metabolites were predominated by acetate and ethanol, with smaller quantities of propionate, butyrate and valerate. Stable ethanol-type fermentation was formed with the sum of ethanol and acetate concentration ratio of 70.31% to the total liquid products after 25 days operation. The H{sub 2} volume content was estimated to be 48-53% of the total biogas and the biogas was free of methane throughout the study. The average biomass concentration was estimated to be 10.82 gVSS/L, which favored H{sub 2} production efficiently. The rate of chemical oxygen demand (COD) removal reached at about 45% and a specific H{sub 2} production rate achieved 0.073 L/gMLVSS d in the study. This CSTR system showed a promising high-efficient bioprocess for H{sub 2} production from high-strength chemical wastewater. (author)

Zhu, Ge-Fu; Wu, Peng; Wei, Qun-Shan; Lin, Jian-yi; Liu, Hai-Ning [Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Gao, Yan-Li [China University of Geosciences, Wuhan 430074 (China)

2010-08-15

34

A New Process Modeling Method Based on Extension Theory and Its Application in Purified Terephthalic Acid Solvent System  

Science.gov (United States)

Owing to the complexity and nonlinearity of chemical process, the intelligent process modeling has become a hot issue. For the purified terephthalic acid (PTA) solvent system, the acetic acid consumption is a crucial production index that has received much more attention in monitoring and guiding the production conditions. In this work, the focus is on the understanding and modeling the influence of operating conditions on acetic acid consumption, which is composed of matter-element model, extension transformation and general regression neural network (GRNN).Thus it comes to an extension engineering method for process modeling of chemical industry. Through the actual application in PTA solvent system of a chemical plant, cases studies show that the proposed method enables us to understand matters in an overall way, to describe thinking process of human beings in a formalized way, to model the chemical process precisely, which exploits a new way to simulate and guide the production process in chemical industry.

Yuan, Xu; Qunxiong, Zhu

35

[Study on the injury of liver induced by terephthalic acid ethylene glycol and/or dowtherm A in rats].  

Science.gov (United States)

The joint injury actions and mechanisms of terephthalic acid (TPA), ethylene glycol (EG) and/or dowtherm A (DOW) on liver in rats were investigated. A subchronic toxicity study was designed by a 2(3) factorial method. Some enzymes, biochemical and morphologic indices reflecting the injury of liver were studied. The results showed that serum ALT and serum total bile acid (TBA) of rats in the combined intoxication groups were significantly higher than those in the groups with single toxic agent and control group. The results of factorial analysis showed that the joint action induced by TPA, EG and/or DOW were characterized as additive (TPA + EG), synergistic (EG + DOW), synergistic (TPA + DOW) and additive(TPA + EG + DOW) actions. The deduction was identified by morphologic observations. PMID:12561562

Yao, Hongwei; Wang, Xinru; Xu, Xikun; Shi, Aimin

2002-02-01

36

Morphology, melting behavior, and non-isothermal crystallization of poly(butylene terephthalate)/poly(ethylene-co-methacrylic acid) blends  

Energy Technology Data Exchange (ETDEWEB)

The morphology, melting behavior, and non-isothermal crystallization of poly(butylene terephthalate) (PBT) and poly(ethylene-co-methacrylic acid) (PEMA) blends were studied with scanning electron microscopy, X-ray diffraction and differential scanning calorimetry (DSC). PEMA forms immiscible, yet compatible, blends with PBT. Subsequent DSC scans on melt-crystallized samples exhibited two melting endotherms (T{sub mI} and T{sub mII}). The presence of PEMA would facilitate the recrystallization during heating scan and retard PBT molecular chains to form a perfect crystal in cooling crystallization. The dispersion phases of molten PEMA acts as nucleating agents to enhance the crystallization rate of PBT. The solidified PBT could act as nucleating agents to enhance the crystallization of PEMA, but also retard the molecular mobility to reduce crystallization rate. The U* and K{sub g} of Hoffman-Lauritzen theory were also determined by Vyazovkin's methods to support the interpretation.

Huang, J.-W. [Department of Styling and Cosmetology, Tainan University of Technology, 529 Chung Cheng Rd., Yung Kang City 710, Taiwan (China)], E-mail: jw.huang@msa.hinet.net; Wen, Y.-L. [Department of Nursing, Meiho Institute of Technology, 23 Ping Kuang Rd., Neipu Hsiang, Pingtung 912, Taiwan (China); Department of Resources Engineering, National Cheng Kung University, No. 1, University Rd., Tainan City 701, Taiwan (China); Kang, C.-C. [R and D Center, Hi-End Polymer Film Co., Ltd. 15-1 Sin Jhong Rd., Sin Ying City 730, Taiwan (China); Yeh, M.-Y. [Department of Chemistry, National Cheng Kung University, No. 1, University Rd., Tainan City 701, Taiwan (China); Sustainable Environment Research Centre, National Cheng Kung University, Taiwan (China); Wen, S.-B. [Department of Nursing, Meiho Institute of Technology, 23 Ping Kuang Rd., Neipu Hsiang, Pingtung 912, Taiwan (China); Department of Resources Engineering, National Cheng Kung University, No. 1, University Rd., Tainan City 701, Taiwan (China)

2007-12-15

37

In situ synthesis of TiO{sub 2}/polyethylene terephthalate hybrid nanocomposites at low temperature  

Energy Technology Data Exchange (ETDEWEB)

TiO{sub 2} nanoflowers were in situ grown on polyethylene terephthalate (PET) non-woven fabric by hydrolysis of TiCl{sub 4} in aqueous solution in the presence of nanocrystal cellulose grafted PET fabric (NCC-g-PET) at a low temperature of 70 Degree-Sign C. Nanocrystal cellulose (NCC) pre-grafted on PET fabric acted as hydrophilic substrate and morphology inducing agent to promote the nucleation and crystal growth of TiO{sub 2}. Detailed information on the synthetic process was presented. The resulting samples were characterized using FE-SEM, EDS, ATR-IR, Raman microscopy, XRD and TG analysis. The photocatalytic activity of the samples was evaluated by the degradation of orange methyl under solar light. Characteristic results indicate that rutile TiO{sub 2} nanoflowers have grown abundantly on PET non-woven fabric, and the established hydrogen bonding strengthens the interfacial interaction between the inorganic particles and the polymeric substrates. The methyl orange decoloration test under natural solar light demonstrates that this TiO{sub 2}/PET hybrid nanocomposites exhibit excellent self-cleaning performance which is expected to have a good potential for commercialization.

Peng Xinyan [College of Materials Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510640 (China); Ding Enyong, E-mail: eyding@scut.edu.cn [College of Materials Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510640 (China); Xue Feng [College of Materials Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510640 (China)

2012-06-15

38

In situ synthesis of TiO2/polyethylene terephthalate hybrid nanocomposites at low temperature  

Science.gov (United States)

TiO2 nanoflowers were in situ grown on polyethylene terephthalate (PET) non-woven fabric by hydrolysis of TiCl4 in aqueous solution in the presence of nanocrystal cellulose grafted PET fabric (NCC-g-PET) at a low temperature of 70 °C. Nanocrystal cellulose (NCC) pre-grafted on PET fabric acted as hydrophilic substrate and morphology inducing agent to promote the nucleation and crystal growth of TiO2. Detailed information on the synthetic process was presented. The resulting samples were characterized using FE-SEM, EDS, ATR-IR, Raman microscopy, XRD and TG analysis. The photocatalytic activity of the samples was evaluated by the degradation of orange methyl under solar light. Characteristic results indicate that rutile TiO2 nanoflowers have grown abundantly on PET non-woven fabric, and the established hydrogen bonding strengthens the interfacial interaction between the inorganic particles and the polymeric substrates. The methyl orange decoloration test under natural solar light demonstrates that this TiO2/PET hybrid nanocomposites exhibit excellent self-cleaning performance which is expected to have a good potential for commercialization.

Peng, Xinyan; Ding, Enyong; Xue, Feng

2012-06-01

39

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

40

Gaseous species as reaction tracers in the solvothermal synthesis of the zinc oxide terephthalate MOF-5.  

Science.gov (United States)

Gaseous species emitted during the zinc oxide/zinc hydroxide 1,4-benzenedicarboxylate metal organic framework synthesis (MOF-5, MOF-69c) have been used to investigate the reaction scheme that leads to the framework creation. Changes of the gas-phase composition over time indicate that the decomposition of the solvent diethylformamide occurs at least via two competing reaction pathways that can be linked to the reaction's overall water and pH management. From isotope exchange experiments, we deduce that one of the decomposition pathways leads to the removal of water from the reaction mixture, which sets the conditions when the synthesis of an oxide-based (MOF-5) instead of an hydroxide-based MOF (MOF-69c) occurs. A quantitative account of most reactants and byproducts before and after the MOF-5/MOF-69c synthesis is presented. From the investigation of the reaction intermediates and byproducts, we derive a proposal of a basic reaction scheme for the standard synthesis zinc oxide carboxylate MOFs. PMID:17455926

Hausdorf, Steffen; Baitalow, Felix; Seidel, Jürgen; Mertens, Florian O R L

2007-05-24

 
 
 
 
41

Development of a bioprocess to convert PET derived terephthalic acid and biodiesel derived glycerol to medium chain length polyhydroxyalkanoate.  

Science.gov (United States)

Sodium terephthalate (TA) produced from a PET pyrolysis product and waste glycerol (WG) from biodiesel manufacture were supplied to Pseudomonas putida GO16 in a fed-batch bioreactor. Six feeding strategies were employed by altering the sequence of TA and WG feeding. P. putida GO16 reached 8.70 g/l cell dry weight (CDW) and 2.61 g/l PHA in 48 h when grown on TA alone. When TA and WG were supplied in combination, biomass productivity (g/l/h) was increased between 1.3- and 1.7-fold and PHA productivity (g/l/h) was increased 1.8- to 2.2-fold compared to TA supplied alone. The monomer composition of the PHA accumulated from TA or WG was predominantly composed of 3-hydroxydecanoic acid. PHA monomers 3-hydroxytetradeeanoic acid and 3-hydroxytetradecenoic acid were not present in PHA accumulated from TA alone but were present when WG was supplied to the fermentation. When WG was either the sole carbon source or the predominant carbon source supplied to the fermentation the molecular weight of PHA accumulated was lower compared to PHA accumulated when TA was supplied as the sole substrate. Despite similarities in data for the properties of the polymers, PHAs produced with WG present in the PHA accumulation phase were tacky while PHA produced where TA was the sole carbon substrate in the polymer accumulation phase exhibited little or no tackiness at room temperature. The co-feeding of WG to fermentations allows for increased utilisation of TA. The order of feeding of WG and TA has an effect on TA utilisation and polymer properties. PMID:22581066

Kenny, Shane T; Runic, Jasmina Nikodinovic; Kaminsky, Walter; Woods, Trevor; Babu, Ramesh P; O'Connor, Kevin E

2012-08-01

42

Synthesis of rigid polyurethane foams from oligoester alcohols based on the residues from the distillation of crude dimethyl terephthalate and recrystallization of the dimethyl terephthalate/dimethyl isophthalate fraction  

Energy Technology Data Exchange (ETDEWEB)

Oligoester alcohols are synthesized from the residues from the distillation of crude dimethyl terephthalate and recrystallization of the fraction dimethyl terephthalate/dimethyl isophthalate, diols, triols, tetrols, and tall oil. The polyol component containing various oligoester alcohols is suitable for preparing rigid polyurethane foams with good thermal stability and improved resistance to combustion.

Troev, K. (Bulgarian Academy of Sciences, Sofia); Todorov, K.; Borisov, G.

1983-08-01

43

Chemical recycling of industrial poly(ethylene terephthalate) waste: synthesis of aromatic polyester polyols, their properties and use  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study, the generation points, reasons and properties of industrial PET waste were examined in detail. Different chemical recycling ways were suggested for each kind of industrial PET waste. Under glycolysis of industrial PET waste by ethylene glycol, the yield of the main product bis(2-hidroxyethylene) terephthalate was higher than 85 %. Several series of aromatic polyester polyols (APP) were synthesized by transesterification of industrial PET waste using diethyleneglycol (DEG) in th...

Vitkauskiene?, Irena

2011-01-01

44

Bile acids: regulation of synthesis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Bile acids are physiological detergents that generate bile flow and facilitate intestinal absorption and transport of lipids, nutrients, and vitamins. Bile acids also are signaling molecules and inflammatory agents that rapidly activate nuclear receptors and cell signaling pathways that regulate lipid, glucose, and energy metabolism. The enterohepatic circulation of bile acids exerts important physiological functions not only in feedback inhibition of bile acid synthesis but also in control o...

Chiang, John Y. L.

2009-01-01

45

Comparative study of thermophilic and mesophilic anaerobic treatment of purified terephthalic acid (PTA wastewater  

Directory of Open Access Journals (Sweden)

Full Text Available The paper provides a critical comparison between mesophilic and thermophilic anaerobic treatment of PTA wastewater through diagnosis of a case study. Aspects covered are bioavailability, biodegradability, microbial population, thermodynamics, kinetics involved and bio-reactor design for PTA wastewater treatment. The results of the case study suggests that one- stage thermophilic anaerobic reactor coupled with coagulation-flocculation pre-treatment unit and an aerobic post treatment unit could be techno-economically viable for PTA wastewater treatment to ensure that the final effluent quality conforms to the international standard. The in-formation emanated from this study could be useful and thought provoking to the professionals and academia in the area of PTA wastewater treatment and can serve as impetus toward the development of research lines in similar problems like the treatment of other petrochemical wastewater such as phenol-con- taining wastewater, benzene/benzoic acid-con- taining wastewater or wastewater from other similar industrial settings.

Adeniyi G. Adeogun

2011-05-01

46

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

47

Quantification of tetramethyl-terephthalic acid in rat liver, spleen and urine matrices by liquid-liquid phase extraction and HPLC-photodiode array detection.  

Science.gov (United States)

Tetramethyl-terephthalate (TMT) is the constitutive linker of the flexible porous iron(III) carboxylate Metal Organic Framework (MOF) MIL-88B_4CH? based drug nanocarrier (MIL stands for Material from Institut Lavoisier). A method for the determination of the concentration of tetramethyl-terephthalic acid has been developed in different biological rat matrices (liver, spleen and urine) using a liquid-liquid phase extraction and high-performance liquid chromatography (HPLC) coupled to photodiode array detection with 4-aminosalicylic acid as internal standard. The extraction conditions of TMT have been varied from urine to tissue depending on the complexity of the biological matrices. The chromatographic separation was performed with a gradient elution. In all matrices, the limits of detection and quantification of TMT was 0.01 and 0.05 ?g ml?¹, respectively. The recovery of the TMT reached 86, 89 and 97% for urine, spleen and liver tissues, respectively. The linearity of the calibration curves in urine and tissues was satisfactory in all cases as evidenced by correlation coefficients >0.990. The within-day and between-day precisions were MIL-88B_4CH? nanoparticles. PMID:22608098

Baati, Tarek; Horcajada, Patricia; David, Olivier; Gref, Ruxandra; Couvreur, Patrick; Serre, Christian

2012-01-01

48

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

49

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

50

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.

51

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

52

Surface modification of poly(ethylene terephthalate) (PET) film by gamma-ray induced grafting of poly(acrylic acid) and its application in antibacterial hybrid film  

International Nuclear Information System (INIS)

Acrylic acid (AA) was facilely grafted onto poly(ethylene terephthalate) (PET) film through gamma-ray induced graft copolymerization. Silver nanoparticles produced by the chemical reduction of silver ions were then immobilized by carboxylic anions and embedded on the surface of PET-g-PAA film. It was found that the DG of PAA on PET film increases with the absorbed dose and would finally control the amount of loaded silver nanoparticles. The prepared PET-g-PAA/Ag hybrid films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The bactericidal activity of the PET-g-PAA/Ag hybrid film was evaluated by the efficiency of killing Escherichia coli. The results showed that the PET-g-PAA/Ag hybrid film has a strong and stable antibacterial activity.

53

Coexistence of one- and two-dimensional supramolecular assemblies of terephthalic acid on Pd(111) due to self-limiting deprotonation  

International Nuclear Information System (INIS)

The adsorption of terephthalic acid [C6H4(COOH)2, TPA] on a Pd(111) surface has been investigated by means of scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy, and near-edge x-ray absorption fine structure spectroscopy under ultrahigh vacuum conditions at room temperature. We find the coexistence of one- (1D) and two-dimensional (2D) molecular ordering. Our analysis indicates that the 1D phase consists of intact TPA chains stabilized by a dimerization of the self-complementary carboxyl groups, whereas in the 2D phase, consisting of deprotonated entities, the molecules form lateral ionic hydrogen bonds. The supramolecular growth dynamics and the resulting structures are explained by a self-limiting deprotonation process mediated by the catalytic activity of the Pd surface. Our models for the molecular ordering are supported by molecular mechanics calculations and a simulation of high resolution STM images

54

Surface modification of poly(ethylene terephthalate) (PET) film by gamma-ray induced grafting of poly(acrylic acid) and its application in antibacterial hybrid film  

Energy Technology Data Exchange (ETDEWEB)

Acrylic acid (AA) was facilely grafted onto poly(ethylene terephthalate) (PET) film through gamma-ray induced graft copolymerization. Silver nanoparticles produced by the chemical reduction of silver ions were then immobilized by carboxylic anions and embedded on the surface of PET-g-PAA film. It was found that the DG of PAA on PET film increases with the absorbed dose and would finally control the amount of loaded silver nanoparticles. The prepared PET-g-PAA/Ag hybrid films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The bactericidal activity of the PET-g-PAA/Ag hybrid film was evaluated by the efficiency of killing Escherichia coli. The results showed that the PET-g-PAA/Ag hybrid film has a strong and stable antibacterial activity.

Ping Xiang [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wang Mozhen, E-mail: pstwmz@ustc.edu.c [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Xuewu Ge, E-mail: xwge@ustc.edu.c [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2011-04-15

55

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.

56

1,4-Bis(4,5-dihydro-1H-imidazol-2-ylbenzene–terephthalic acid–water (1/1/4  

Directory of Open Access Journals (Sweden)

Full Text Available The asymmetric unit of the title compound, C12H14N4·C8H6O4·4H2O, consists of one half of the 1,4-bis(4,5-dihydro-1H-imidazol-2-ylbenzene (bib molecule, one half of the terephthalic acid (TA molecule and two water molecules. Both the bib and the TA molecules reside on crystallographic inversion centers, which coincide with the centroids of the respective benzene rings. The bib and the TA, together with the water molecules, are linked through intermolecular O—H...O, O—H...N and N—H...O hydrogen bonds, forming a three-dimensional network of stacked layers. Weak intermolecular C—H...O contacts support the stability of the crystal structure.

Shao-Ming Shang

2009-11-01

57

Total synthesis of (+)-lysergic acid.  

Science.gov (United States)

We report the enantioselective total synthesis of (+)-lysergic acid using two different strategies, which featured three metal-catalyzed reactions for the construction of the BCD three rings, involving Pd-catalyzed indole synthesis for the construction of the B ring, a ring-closing metathesis reaction for the formation of the D ring, and an intramolecular Heck reaction to forge the C ring. In synthetic strategy I, the synthesis was achieved in 20 steps following the ring construction sequence of BDC. In synthetic strategy II, the synthetic route was shortened to only 12 steps by following the ring construction sequence of DBC and using a 4-chlorotryptophan derivative for the intramolecular Heck reaction. Moreover, we also discussed an unsuccessful synthetic strategy. PMID:24111583

Liu, Qiang; Zhang, Yu-An; Xu, Ping; Jia, Yanxing

2013-11-01

58

Preparation of polymer blends from glycerol, fumaric acid and of poly(ethylene terephthalate) (PET) recycled; Preparacao de blendas polimericas a partir do glicerol, acido fumarico e do politereftalato de etileno (PET) pos consumo  

Energy Technology Data Exchange (ETDEWEB)

Polymer blends based on recycled poly(ethylene terephthalate) (PET) and poly(glycerol fumarate) polyesters were prepared in different PET concentrations. The PET powder was dispersed during the poly(glycerol fumarate) synthesis at 260 deg C. The resulting blends were characterized by X-ray diffraction. The thermal stability of the materials was evaluated by thermogravimetric analysis and differential scanning calorimetry. The morphology was studies by scanning electron microscopy. The blends were clearly immiscible. The possibility of (interfacial) compatibilization of the PET domains, caused by transesterification reactions between PET and glycerol were discussed. (author)

Medeiros, Marina A.O.; Guimaraes, Danilo H.; Brioude, Michel M.; Jose, Nadia M. [Instituto de Quimica, Universidade Federal da Bahia, Salvador, BA (Brazil); Prado, Luis A.S. de A. [Institut fuer Kunststoffe und Verbundwerkstoffe - Technische Universitaet Hamburg-Harburg, Hamburg (Germany)

2011-07-01

59

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.

60

Corrosion of an amorphous indium tin oxide film on polyethylene terephthalate at low concentrations of acrylic acid  

International Nuclear Information System (INIS)

Highlights: ? Corrosion of ITO film on polymer substrate. ? Removal of In from ITO in acrylic acid. ? Degradation of conductivity of ITO film with acrylic adhesives. - Abstract: The corrosion behavior of ITO film deposited at low temperature on a polymer substrate by DC magnetron sputtering is studied in 0.05 M acrylic acid to investigate possible corrosion in contact with acrylic adhesives, which are employed in the fabrication of flexible optoelectronic devices. The shift in steady state open circuit potential (OCP) to negative values in electrochemical measurements suggests the increase in dissolution of ITO film with increasing immersion time. The potentiodynamic polarization results show an increase in Ecorr and a decrease in Icorr to lower values with time. This suggests that the electro-activity of ITO film decreases with increasing immersion time. Scanning electron microscopy shows corrosion of the ITO film. X-ray photoelectron spectroscopy analysis indicates a gradual removal of indium from the ITO layer. Electrochemical impedance spectroscopy analysis reveals two time constants and an increase in the charge transfer resistance of the Nyquist plot which suggests a decrease in the conductivity of ITO film with increasing immersion time. Both the electrochemical and surface characterization studies suggest a degradation of the conductivity of ITO film with increasing immersion time in 0.05 M acrylic acid.c acid.

 
 
 
 
61

Corrosion of an amorphous indium tin oxide film on polyethylene terephthalate at low concentrations of acrylic acid  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer Corrosion of ITO film on polymer substrate. Black-Right-Pointing-Pointer Removal of In from ITO in acrylic acid. Black-Right-Pointing-Pointer Degradation of conductivity of ITO film with acrylic adhesives. - Abstract: The corrosion behavior of ITO film deposited at low temperature on a polymer substrate by DC magnetron sputtering is studied in 0.05 M acrylic acid to investigate possible corrosion in contact with acrylic adhesives, which are employed in the fabrication of flexible optoelectronic devices. The shift in steady state open circuit potential (OCP) to negative values in electrochemical measurements suggests the increase in dissolution of ITO film with increasing immersion time. The potentiodynamic polarization results show an increase in E{sub corr} and a decrease in I{sub corr} to lower values with time. This suggests that the electro-activity of ITO film decreases with increasing immersion time. Scanning electron microscopy shows corrosion of the ITO film. X-ray photoelectron spectroscopy analysis indicates a gradual removal of indium from the ITO layer. Electrochemical impedance spectroscopy analysis reveals two time constants and an increase in the charge transfer resistance of the Nyquist plot which suggests a decrease in the conductivity of ITO film with increasing immersion time. Both the electrochemical and surface characterization studies suggest a degradation of the conductivity of ITO film with increasing immersion time in 0.05 M acrylic acid.

Bejitual, T.S.; Ramji, K.; Kessman, A.J.; Sierros, K.A. [Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, West Virginia 26506 (United States); Cairns, D.R., E-mail: darran.cairns@mail.wvu.edu [Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, West Virginia 26506 (United States)

2012-02-15

62

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

63

Synthesis of tritium labelled fluorescent eicosapolyenoic acids  

International Nuclear Information System (INIS)

A synthesis of tritium labelled fluorescent eicosapolyenoic acids from /5, 6, 8, 9, 11, 12, 14, 15 - 3H8/ -arachidonic acid is described. The bromination-debromination steps resulted in a mixture of tritiated eicosapolyenoic acids with a system of five conjugated double bonds and ?max at 330 nm. Reaction products were separated by RP-HPLC and their fluorescent parameters were measured. Fluorescent eicosapolyenoic acids had emission max at 470 nm ( ?ex 346 nm). The molar radioactivity of acids obtained was in the range 3.3 - 5.6 TBq/mmol. (author). 3 refs

64

Fatty acid synthesis by spinach chloroplasts, 2  

International Nuclear Information System (INIS)

y acids than acetylCoA, it is unlikely that pyruvate decarboxylation to acetylCoA is due to mitochondria contaminating the chloroplast preparation. On the basis of measurements of 3H2O incorporation in the light and dark, the activity of fatty acid synthesis in spincah leaves appears to be shared by the activities in chloroplasts (87%) and other organelles (13%). (author)

65

Synthesis and NMR characterization of aliphatic-aromatic copolyesters by reaction of poly(ethylene terephthalate post-consumer and poly(ethylene adipate  

Directory of Open Access Journals (Sweden)

Full Text Available An aliphatic-aromatic copolyester of poly(ethylene terephthalate, PET, and poly(ethylene adipate, PEA, PET-co-PEA, was synthesized by the high temperature melt reaction of post-consumer PET and PEA. As observed by NMR spectroscopy, the reaction yielded random copolyesters in a few minutes through ester-interchange reactions, even without added catalyst. The copolyesters obtained in the presence of a catalyst presented higher intrinsic viscosity than that obtained without the addition of catalyst, due to simultaneous polycondensation and ester-interchange reactions. The structure of the aliphatic-aromatic copolyesters obtained in different PET/PEA ratio is random as observed by NMR analysis.

Alessandra F. Baldissera

2005-03-01

66

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

67

Preparation and characterization of polymer blends based on recycled PET and polyester derived by terephthalic acid; Preparacao e caracterizacao de blendas polimericas a base de PET reciclado e poliester derivado do acido tereftalico  

Energy Technology Data Exchange (ETDEWEB)

Environmentally friendly materials, made from industrial waste, are being increasingly used as a solution to the growing amount of waste generated by society, but also as a cheaper alternative to replace conventional materials for use in construction. In this work were investigated the properties of polymer blends based on recycled PET and a polyester derived from terephthalic acid and glycerin, a co-product of biodiesel. The samples were characterized by XRD, TGA, DSC, FTIR and SEM. The polyester synthesized showed a degradation event near 300 deg C. The blends with higher ratio of PET showed thermal behavior similar to pure PET. The X-ray diffraction showed that the polymer blends are semicrystalline materials. The micrographs presents the presence of a smooth surface, indicating the possibility of miscibility between the arrays. Therefore, the blending makes possible the fabrication of low-cost materials with applications in several areas. (author)

Ohara, L.; Miranda, C.S.; Fiuza, R.P.; Luporini, S.; Carvalho, R.F.; Jose, N.M., E-mail: leandro.ohara@gmail.co [Universidade Federal da Bahia (GECIM/UFBA), Salvador, BA (Brazil). Inst. de Quimica. Grupo de Energia e Ciencias dos Materiais

2010-07-01

68

Features of fatty acid synthesis in higher plants  

International Nuclear Information System (INIS)

In the biosynthesis of fatty acid in the presence of 3H2O, 3H is incorporated into the hydrocarbon chain of the fatty acid. The features in the fatty acid synthesis of higher plants were investigated by applying 3H2O method to the measurement of the ability of spinach leaves synthesizing fatty acid. Sucrose, acetate, pyruvate, PGA, PEP, OAA, citrate, etc. were employed as the substrates of fatty acid synthesis to trace the process of synthesis of each fatty acid. The demand of various cofactors related to the ability of spinach chloroplast fatty acid synthesizing was also examined. Light dependence of the fatty acid synthesis of chloroplast as well as the influences of N,N'-dicyclohexyl carbodiimide, carbonylcyanide-4-trifluoromethoxy phenyl hydrazone and NH4Cl were discussed. The results were compared with the reports on the fatty acid synthesis of avocado pear, castor bean, etc. (Kobatake, H.)

69

On the Diels-Alder approach to solely biomass-derived polyethylene terephthalate (PET): conversion of 2,5-dimethylfuran and acrolein into p-xylene.  

Science.gov (United States)

Polyethylene terephthalate (PET) is a polymeric material with high global demand. Conventionally, PET is produced from fossil-fuel-based materials. Herein, we explored the feasibility of a sustainable method for PET production by using solely bio-renewable resources. Specifically, 2,5-dimethylfuran (derived from lignocellulosic biomass through 5-(hydroxymethyl)furfural) and acrolein (produced from glycerol, a side product of biodiesel production) were converted into the key intermediate p-xylene (a precursor of terephthalic acid). This synthesis consists of a sequential Diels-Alder reaction, oxidation, dehydration, and decarboxylation. In particular, the pivotal first step, the Diels-Alder reaction, was studied in detail to provide useful kinetic and thermodynamic data. Although it was found that this reaction requires low temperature to proceed efficiently, which presents a limitation on economic feasibility on an industrial scale, the concept was realized and bio-derived p-xylene was obtained in 34% overall yield over four steps. PMID:21922576

Shiramizu, Mika; Toste, F Dean

2011-10-24

70

Regulation of ascorbic acid synthesis in plants.  

Science.gov (United States)

Ascorbic acid (AsA) is a major antioxidant and plays an important role in plant growth and development. There are two aspects to improve AsA content, including de novo synthesis and recycling from its oxidized form. However, the knowledge of regulatory mechanisms of AsA synthesis pathways and metabolism still remains limited. We have determined that AsA synthesis process was modulated on both transcriptional and post-transcriptional levels in Arabidopsis. GDP-mannose pyrophosphorylase (VTC1) is the initial AsA biosynthetic enzyme in L-galactose pathway, we previously showed that Arabidopsis ERF98 transcriptionally activates gene expression of VTC1 to improve AsA content and respond salt stress; recent discovery of the interaction between photomorphogenic factor COP9 signalosome (CSN) subunit CSN5B and VTC1 indicates that CSN5B promotes VTC1 degradation in the dark, which keeps the change of AsA content from day to night. This mini-review integrates previous reports and recent evidence to better understand the regulatory mechanisms involved in AsA synthesis. PMID:23603957

Wang, Juan; Zhang, Zhijin; Huang, Rongfeng

2013-06-01

71

Synthesis of bis-(?-trifluoromethylphenyl) dithiophosphinic acid  

International Nuclear Information System (INIS)

The synthetic method of bis-(?-trifluoromethylphenyl) dithiophosphinic acid has been improved during the synthetic research of various dithiophosphinic acids. The optimized synthesis has been realized with PCl3 and (?-F3CC6H4) MgBr as starting materials and via a continuous three-step method including Grignard reaction, sulfuration and substitution reaction. The FTIR spectrum of product shows the presence of substituted aromatic ring, C-F bond, P-S single bond and P=S double bond. The interpretation result f 31P NMR, 1H NMR and 13C NMR of the product, as well as MS, is completely in line with the structure of the targeted compound bis-(?-trifluoromethylphenyl) dithiophosphinic acid. (authors)

72

High-rate treatment of terephthalate in anaerobic hybrid reactors.  

Science.gov (United States)

The anaerobic degradation of terephthalate as sole substrate was studied in three anaerobic upflow reactors. Initially, the reactors were operated as upflow anaerobic sludge bed (UASB) reactors and seeded with suspended methanogenic biomass obtained from a full-scale down-flow fixed film reactor, treating wastewater generated during production of purified terephthalic acid. The reactors were operated at 30, 37, and 55 degrees C. The terephthalate removal capacities remained low in all three reactors (<4 mmolxL-1xday-1, or 1 g of chemical oxygen demand (COD)xL-1xday-1) due to limitations in biomass retention. Batch experiments with biomass from the UASB reactors revealed that, within the mesophilic temperature range, optimal terephthalate degradation is obtained at 37 degrees C. No thermophilic terephthalate-degrading culture could be obtained in either continuous or batch cultures. To enhance biomass retention, the reactors were modified to anaerobic hybrid reactors by introduction of two types of reticulated polyurethane (PUR) foam particles. The hybrid reactors were operated at 37 degrees C and seeded with a mixture of biomass from the UASB reactors operated at 30 and 37 degrees C. After a lag period of approximately 80 days, the terephthalate conversion capacity of the hybrid reactors increased exponentially at a specific rate of approximately 0.06 day-1, and high removal rates were obtained (40-70 mmolxL-1xday-1, or 10-17 g of CODxL-1xday-1) at hydraulic retention times between 5 and 8 h. These high removal capacities could be attributed to enhanced biomass retention by the development of biofilms on the PUR carrier material as well as the formation of granular biomass. Biomass balances over the hybrid reactors suggested that either bacterial decay or selective wash-out of the terephthalate fermenting biomass played an important role in the capacity limitations of the systems. The presented results suggest that terephthalate can be degraded at high volumetric rates if sufficiently long sludge ages can be maintained, and the reactor pH and temperature are close to their optima. PMID:10356251

Kleerebezem, R; Ivalo, M; Hulshoff Pol, L W; Lettinga, G

1999-01-01

73

Chemical synthesis of a hyaluronic acid decasaccharide.  

Science.gov (United States)

The chemical synthesis of a hyaluronic acid decasaccharide using the preactivation-based chemoselective glycosylation strategy is described. Assembly of large oligosaccharides is generally challenging due to the increased difficulties in both glycosylation and deprotection. Indeed, the same building blocks previously employed for hyaluronic acid hexasaccharide syntheses failed to yield the desired decasaccharide. After extensive experimentation, the decasaccharide backbone was successfully constructed with an overall yield of 37% from disaccharide building blocks. The trichloroacetyl group was used as the nitrogen protective group for the glucosamine units, and the addition of TMSOTf was found to be crucial to suppress the formation of trichloromethyl oxazoline side product and enable high glycosylation yield. For deprotections, the combination of a mild basic condition and the monitoring methodology using (1)H NMR allowed the removal of all base-labile protective groups, which facilitated the generation of the fully deprotected HA decasaccharide. PMID:19764799

Lu, Xiaowei; Kamat, Medha N; Huang, Lijun; Huang, Xuefei

2009-10-16

74

Catalysis of the Carbonylation of Alcohols to Carboxylic Acids Including Acetic Acid Synthesis from Methanol.  

Science.gov (United States)

Monsanto's highly successful synthesis of acetic acid from methanol and carbon monoxide illustrates use of new starting materials to replace pretroleum-derived ethylene. Outlines the fundamental aspects of the acetic acid process and suggests ways of extending the synthesis to higher carboxylic acids. (JN)

Forster, Denis; DeKleva, Thomas W.

1986-01-01

75

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

76

Fatty acid synthesis by spinach chloroplasts, 1  

International Nuclear Information System (INIS)

Intact chloroplasts (about 70% Class I chloroplasts) isolated from spinach leaves incorporated 150 nmoles of [1-14C] acetate into fatty acids per mg chlorophyll in 1 hr at pH 8.3, 250C and 25,000 lux. On electron and phase-contrast microscopies combined with hypotonic treatment of chloroplasts, this synthetic activity was shown to be proportional to the percentage of Class I chloroplasts in the preparation. Light was necessary for the synthesis, the activity in the complete reaction mixture in the dark being only 2% of that in the light. The synthetic activity increased with increasing intensities of light to reach saturation at 6000 lux. CoA and ATP were most effective as cofactors, HCO3-, HPO42-, Mg2+ and Mn2+ were less effective. ATP could be replaced by ADP in the presence of Pi, suggesting possible supply of ATP by photophosphorylation. Omission of the NADPH-generation system and NADH did not affect the synthesis, indicating sufficient provision of endogenous NADPH and NADH in intact chloroplasts under light. Addition of DTE did not cause recovery of the synthetic activity of intact chloroplasts in the dark. (author)

77

Synthesis of Diaminopimelic Acid, Lysine and Pipecolic Acid from Spartic Acid by Rumen Microorganisms  

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Full Text Available The current study was examined the formation of the three Stereoisomers (SI of 2, 6-Diaminopimelic Acid (DAP, lysine and pipecolic acid from aspartic acid by mixed rumen bacteria and protozoa. Mixed rumen bacteria and protozoa were isolated from the rumen of sheep given concentrate mixture and hay and incubated with and without aspartic acid (5 mM. The microbial suspensions were anaerobically incubated at 39°C for 12 h. The results showed that mixed rumen bacteria produced meso-DAP by 0.221 mM, LL-DAP by 0.013 mM, lysine by 0.211 mM during the 12 h incubation periods. This is the first finding to show the synthesis of DAP-SI and lysine from aspartic acid by rumen bacteria. Mixed rumen protozoa produced meso-DAP by 0.231 mM, lysine by 0.443 mM and pipecolic acid by 0.042 mM during the 12 h incubation periods. DD-DAP was not detected during the incubation periods of mixed rumen bacteria and protozoa and also LL-DAP was not detected by mixed rumen protozoa. The synthesis meso-DAP from aspartic acid by rumen protozoa was demonstrated for the first time. The results indicated that mixed rumen bacteria have the ability to synthesis meso-DAP, LL-DAP and lysine from aspartic acid meanwhile, the mixed rumen protozoa have the ability to produced meso-DAP, lysine and pipecolic acid from aspartic acid.

A.M. El-Waziry

2012-01-01

78

Synthesis of bile acid coenzyme a thioesters in the amino acid conjugation of bile acids.  

Science.gov (United States)

Bile acids are converted to their glycine and taurine N-acyl amidates by enzymes in the liver in a two-step process. This conjugation reaction increases the aqueous solubility of bile acids, particularly in the acidic environment of the initial portion of the small intestine. In the first step, bile acid coenzyme A (CoA) thioesters are formed by a bile acid CoA ligase (BAL). This chapter describes the methods used to purify BAL from rat liver microsomes and to isolate and clone the cDNAs encoding BAL from a rat liver cDNA library, the expression of BAL, the assays used to measure its activities, and the chemical synthesis of bile acid CoA thioesters. PMID:16399360

Shonsey, Erin M; Wheeler, James; Johnson, Michelle; He, Dongning; Falany, Charles N; Falany, Josie; Barnes, Stephen

2005-01-01

79

Tetramethylammonium hemi(terephthalate) dihydrate  

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In the title compound, (CH3)4N+·0.5C8H4O42?·2H2O, the complete terephthalate dianion is completed by twofold symmetry and has a dihedral angle of 23.5?(2)° between the carboxylate group and its parent ring. Two independent water molecules serve as both donors and acceptor in the construction of undulating hydrogen-bonded host layers with various O—H...O contacts ocurring between the anion and two water molecules. At the same time, the t...

Yunxia Yang; Laipeng Shi

2011-01-01

80

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

 
 
 
 
81

Microwave-Promoted synthesis of novel N-Arylanthranilic acids  

International Nuclear Information System (INIS)

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. (author)

82

Microwave-Promoted synthesis of novel N-Arylanthranilic acids  

Energy Technology Data Exchange (ETDEWEB)

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. (author)

Bueno, Mauro A.; Silva, Larissa R.S.P.; Correa, Arlene G. [Universidade Federal de Sao Carlos (UFSCAR), Sao Carlos, SP (Brazil). Dept. de Quimica]. E-mail: agcorrea@power.ufscar.br

2008-07-01

83

The Two Carboxylases of Corynebacterium glutamicum Essential for Fatty Acid and Mycolic Acid Synthesis? †  

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The suborder Corynebacterianeae comprises bacteria like Mycobacterium tuberculosis and Corynebacterium glutamicum, and these bacteria contain in addition to the linear fatty acids, unique ?-branched ?-hydroxy fatty acids, called mycolic acids. Whereas acetyl-coenzyme A (CoA) carboxylase activity is required to provide malonyl-CoA for fatty acid synthesis, a new type of carboxylase is apparently additionally present in these bacteria. It activates the ?-carbon of a linear fatty acid by carb...

2007-01-01

84

Nucleic acid arrays and methods of synthesis  

Energy Technology Data Exchange (ETDEWEB)

The present invention generally relates to high density nucleic acid arrays and methods of synthesizing nucleic acid sequences on a solid surface. Specifically, the present invention contemplates the use of stabilized nucleic acid primer sequences immobilized on solid surfaces, and circular nucleic acid sequence templates combined with the use of isothermal rolling circle amplification to thereby increase nucleic acid sequence concentrations in a sample or on an array of nucleic acid sequences.

Sabanayagam, Chandran R. (Allston, MA); Sano, Takeshi (Needham, MA); Misasi, John (Syracuse, NY); Hatch, Anson (Seattle, WA); Cantor, Charles (Del Mar, CA)

2001-01-01

85

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  

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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

86

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.

87

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 bile acid synthesis in man

88

Fatty Acid Synthesis by Indonesian Marine Diatom, Chaetoceros gracilis  

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Full Text Available Since the primary storage nutrients in diatoms consist of lipid, they are potential for the industrial fatty acid production. High value fatty acids include arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid. This study aimed to analyze fatty acid synthesis by Chaetoceros gracilis diatom during growth. There was a large increase in lipid yield from 4pg cell-1 mass of lipid per cell at the exponential phase to 283pg cell-1 at stationary phase. The lipid concentrations also increased significantly from the stationary phase to the death phase, but not significantly from the end exponential phase to the stationary phase. The relative percentage of saturated fatty acid (SAFA of the total fatty acid was higher than that of monounsaturated fatty acid (MUFA and polyunsaturated fatty acid (PUFA at all of growth phase. The highest PUFA was found at stationary phase at the same time when SAFA was being the lowest. The majority of SAFA was palmitic acid (24.03-40.35%. MUFA contained significant proportion of oleic acid (19.6-20.9%. Oleic acid, linoleic acid and ?-linolenic acid were found at every stage growth. These fatty acids are considered as precursor for production of long chain PUFA-Docosahexaenoic acid (DHA/22:6?3 through series of desaturation and elongation step with all of desaturase enzyme (?8-D, ?9-D, ?12-D, ?15-D, ?17-D, ?6-D, ?5-D, and ?4-D and elongase enzyme (E.

ALBERTA RIKA PRATIWI

2009-12-01

89

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

90

Synthesis and characterization of polyamide and polyester, from glycerol and dicarboxylic acids, polymeric blends  

International Nuclear Information System (INIS)

In this work were prepared and characterized polyamide and polyester blends. The polyester, called PAT, was produced in a becker equipped with high-torque mechanical stirrer, thermometer and condenser Claisen, by adding of glycerol, adipic acid, terephthalic acid and catalyst. The blends films were prepared by physical mixture followed by thermal compression. The polymeric blends and the pure materials were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the blends are semi-crystalline and have good thermal behavior, besides, it evidences that the PAT and polyamide phases are immiscible. (author)

91

Kinetic investigation of erucamide synthesis using fatty acid and urea.  

Science.gov (United States)

Fatty acid amides like erucamide are mainly used for lubrication and as slip agent to decrease friction in polymer and plastic industry. Erucamide is normally synthesized by ammonolysis of triglycerides or fatty acids at 200 degrees C and at high pressure (345-690 kPa.). However using urea in place of ammonia the economic synthesis of erucamide is possible at atmospheric pressure at approx 190 degrees C. In present investigation, the kinetics of synthesis of erucamide by ammonolysis of erucic acid has been investigated. The optimum conditions for the synthesis of erucamide have also been determined. 1:4 molar ratio of erucic acid to urea, 190 degrees C temperature and catalyst [P2O5 with (NH4)2H PO4, {(1:1) w/w }] concentration 3% (by wt. of erucic acid) were the optimum condition for synthesis of erucamide from erucic acid and can obtain a maximum yield of 92% of pure erucamide. Some other catalysts as titanium-iso -propoxide, phosphorus pent oxide were also tried but these catalysts were not economical. PMID:18685229

Awasthi, Neeraj Praphulla; Upadhayay, Santosh K; Singh, R P

2008-01-01

92

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)

93

Differential diagnosis in patients with suspected bile acid synthesis defects  

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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

94

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

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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

95

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)

96

Lipase-catalyzed synthesis of fatty acid amide (erucamide) using fatty acid and urea.  

Science.gov (United States)

Ammonolysis of fatty acids to the corresponding fatty acid amides is efficiently catalysed by Candida antartica lipase (Novozym 435). In the present paper lipase-catalysed synthesis of erucamide by ammonolysis of erucic acid and urea in organic solvent medium was studied and optimal conditions for fatty amides synthesis were established. In this process erucic acid gave 88.74 % pure erucamide after 48 hour and 250 rpm at 60 degrees C with 1:4 molar ratio of erucic acid and urea, the organic solvent media is 50 ml tert-butyl alcohol (2-methyl-2-propanol). This process for synthesis is economical as we used urea in place of ammonia or other amidation reactant at atmospheric pressure. The amount of catalyst used is 3 %. PMID:17898456

Awasthi, Neeraj Praphulla; Singh, R P

2007-01-01

97

Synthesis and antituberculosis activity of new fatty acid amides.  

Science.gov (United States)

This work reports the synthesis of new fatty acid amides from C16:0, 18:0, 18:1, 18:1 (OH), and 18:2 fatty acids families with cyclic and acyclic amines and demonstrate for the first time the activity of these compounds as antituberculosis agents against Mycobacterium tuberculosis H(37)Rv, M. tuberculosis rifampicin resistance (ATCC 35338), and M. tuberculosis isoniazid resistance (ATCC 35822). The fatty acid amides derivate from ricinoleic acid were the most potent one among a series of tested compounds, with a MIC 6.25 microg/mL for resistance strains. PMID:20667727

D'Oca, Caroline Da Ros Montes; Coelho, Tatiane; Marinho, Tamara Germani; Hack, Carolina Rosa Lopes; Duarte, Rodrigo da Costa; da Silva, Pedro Almeida; D'Oca, Marcelo Gonçalves Montes

2010-09-01

98

Biodegradation of dimethyl terephthalate by Pasteurella multocida Sa follows an alternative biochemical pathway.  

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Pasteurella multocida Sa, a bacterial strain isolated from mangrove sediment by enrichment technique, was capable of transforming dimethyl terephthalate (DMT). Biodegradation of DMT was shown to take place as a series of sequential steps involving the hydrolysis of two ester linkages between the carboxyl groups of the terephthalate and the methyl side-chain initially to produce mono-methyl terephthalate (MMT) and then terephthalic acid (TA), respectively. However, with ethanol as the carrying solvent, there was a formation of one metabolite previously not observed. The two metabolites were characterized by high performance-liquid chromatography-electron ionization mass spectrometry as MMT and mono-ethyl terephthalate (MET), suggesting the existence of an alternative biochemical pathway in the degradation of DMT by P. multocida Sa. Since the presence of MMT and ethanol in culture inoculated with P. multocida Sa was prerequisites for the formation of MET, biologically mediated trans-esterification was proposed as a mechanism for the novel biochemical process observed. PMID:16676217

Li, Jiaxi; Gu, Ji-Dong

2006-05-01

99

Network dimensionality and ligand flexibility in lanthanide terephthalate hydrates  

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Various lanthanide open framework materials incorporating the terephthalate (TP) entity were prepared using hydrothermal synthesis methods at a moderate temperature of 170 °C. The compounds Nd 2(TP) 3(H 2O) 4( 1), Er 2(TP) 3(H 2O) 4( 2), Yb 2(TP) 3(H 2O) 2( 3), Yb 2(TP) 3(H 2O) 6( 4), and Yb 2(TP) 3(H 2O) 8·2H 2O ( 5), were characterized by single crystal structural analysis and FT-IR spectroscopy. While compounds 1 and 2 have been reported before on the basis of powder X-ray diffraction, the structural characterization of any ytterbium terephthalate species is unprecedented. Compounds 1- 5 crystallize in triclinic settings with space group P-1. The compounds are compared with their previously reported Er and Tb-counterparts and the reduction of the dimensionality of the resulting networks from 3D over 2D to 1D with increasing level of hydration is discussed. Compounds 1, 2, and 3 with the lowest water content assemble in three-dimensional network lattices. Compounds 4 and 5, however, form 2D layered systems and 1D rod like chains, respectively, which are held together by hydrogen bonds originating from coordinating H 2O. The crystal lattices of the 3D networks experience higher levels of tension as can be seen by increasing out-of-plane torsion with regard to the terephthalate carboxylate groups. Moreover, there seems to be a correlation between the level of strain on the aromatic ligands and the reduction of the number of carboxylate oxygen atoms that are part of the coordination polyhedra.

Zehnder, Ralph A.; Renn, Robert A.; Pippin, Ethan; Zeller, Matthias; Wheeler, Kraig A.; Carr, Jason A.; Fontaine, Nick; McMullen, Nathan C.

2011-01-01

100

An efficient synthesis of tetramic acid derivatives with extended conjugation from L-Ascorbic Acid  

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Full Text Available Abstract Background Tetramic acids with polyenyl substituents are an important class of compounds in medicinal chemistry. Both solid and solution phase syntheses of such molecules have been reported recently. Thiolactomycin, a clinical candidate for treatment of tuberculosis has led to further explorations in this class. We have recently developed an efficient synthesis of tetramic acids derivatives from L- ascorbic acid. In continuation of this work, we have synthesised dienyl tetramic acid derivatives. Results 5,6-O-Isopropylidene-ascorbic acid on reaction with DBU led to the formation of tetronolactonyl allyl alcohol, which on oxidation with pyridinium chlorochromate gave the respective tetranolactonyl allylic aldehydes. Wittig olefination followed by reaction of the resulting tetranolactonyl dienyl esters with different amines resulted in the respective 5-hydroxy lactams. Subsequent dehydration of the hydroxy lactams with p-toluene sulphonic acid afforded the dienyl tetramic acid derivatives. All reactions were performed at ambient temperature and the yields are good. Conclusion An efficient and practical method for the synthesis of dienyl tetramic acid derivatives from inexpensive and easily accessible ascorbic acid has been developed. The compounds bear structural similarities to the tetramic acid based polyenic antibiotics and thus this method offers a new and short route for the synthesis of tetramic acid derivatives of biological significance.

Bisht Surendra S

2006-12-01

 
 
 
 
101

Cyclic phosphatidic acid and lysophosphatidic acid induce hyaluronic acid synthesis via CREB transcription factor regulation in human skin fibroblasts.  

Science.gov (United States)

Cyclic phosphatidic acid (cPA) is a naturally occurring phospholipid mediator and an analog of the growth factor-like phospholipid lysophosphatidic acid (LPA). cPA has a unique cyclic phosphate ring at the sn-2 and sn-3 positions of its glycerol backbone. We showed before that a metabolically stabilized cPA derivative, 2-carba-cPA, relieved osteoarthritis pathogenesis in vivo and induced hyaluronic acid synthesis in human osteoarthritis synoviocytes in vitro. This study focused on hyaluronic acid synthesis in human fibroblasts, which retain moisture and maintain health in the dermis. We investigated the effects of cPA and LPA on hyaluronic acid synthesis in human fibroblasts (NB1RGB cells). Using particle exclusion and enzyme-linked immunosorbent assays, we found that both cPA and LPA dose-dependently induced hyaluronic acid synthesis. We revealed that the expression of hyaluronan synthase 2 messenger RNA and protein is up-regulated by cPA and LPA treatment time dependently. We then characterized the signaling pathways up-regulating hyaluronic acid synthesis mediated by cPA and LPA in NB1RGB cells. Pharmacological inhibition and reporter gene assays revealed that the activation of the LPA receptor LPAR1, Gi/o protein, phosphatidylinositol-3 kinase (PI3K), extracellular-signal-regulated kinase (ERK), and cyclic adenosine monophosphate response element-binding protein (CREB) but not nuclear factor ?B induced hyaluronic acid synthesis by the treatment with cPA and LPA in NB1RGB cells. These results demonstrate for the first time that cPA and LPA induce hyaluronic acid synthesis in human skin fibroblasts mainly through the activation of LPAR1-Gi/o followed by the PI3K, ERK, and CREB signaling pathway. PMID:24845645

Maeda-Sano, Katsura; Gotoh, Mari; Morohoshi, Toshiro; Someya, Takao; Murofushi, Hiromu; Murakami-Murofushi, Kimiko

2014-09-01

102

Synthesis of amorphous acid iron phosphate nanoparticles  

Energy Technology Data Exchange (ETDEWEB)

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 Degree-Sign C produces strong compacts of amorphous nanoparticles with interconnected porosity.

Palacios, E., E-mail: epalacios@icv.csic.es; Leret, P.; Fernandez, J. F.; Aza, A. H. De; Rodriguez, M. A. [Instituto de Ceramica y Vidrio, ICV-CSIC (Spain)

2012-10-15

103

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.

104

Synthesis of 1,2,3,4-butanetetracarboxylic acid from the irradiation of aqueous succinic acid  

International Nuclear Information System (INIS)

This paper deals with the action of ionizing radiation on diluted aqueous solutions of succinic acid in order to synthesize 1,2,3,4-butanetetracarboxylic acid. This compound has a variety of industrial and agricultural applications. The chemical synthesis of this compound involves several steps. In contrast the radiation-induced synthesis can be achieved in one step and with a good yield. The results obtained show that one of the most important reactions was the dimerization of the target compound yielding the tetracarboxylic acid. (author)

105

Microscale synthesis of volatile, 14C-labeled acid chlorides  

International Nuclear Information System (INIS)

A method for the microscale (one mmole) synthesis of volatile, 14C-labelled acid chlorides from Ba14CO3 using vacuum line techniques is described. By a judicious choice of reagents, desired intermediates and products may be isolated in high yield by simple vacuum transfer techniques without fractionation. (author)

106

Synthesis and Evaluation of Photoreactive Tetrazole Amino Acids  

Science.gov (United States)

Six photoreactive tetrazole amino acids were efficiently synthesized either by the de novo Kakehi tetrazole synthesis method or by alkylation of a glycine Schiff base with tetrazole-containing alkyl halides, and four of them showed excellent reactivity toward a simple alkene in the photoinduced 1,3-dipolar cycloaddition reaction in acetonitrile/PBS buffer (1:1) mixture. PMID:19637915

Wang, Yizhong; Lin, Qing

2009-01-01

107

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

108

Stereoselective synthesis of stable-isotope-labeled amino acids  

International Nuclear Information System (INIS)

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 ?-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

109

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

110

Synthesis and chirality of amino acids under interstellar conditions.  

Science.gov (United States)

Amino acids are the fundamental building blocks of proteins, the biomolecules that provide cellular structure and function in all living organisms. A majority of amino acids utilized within living systems possess pre-specified orientation geometry (chirality); however the original source for this specific orientation remains uncertain. In order to trace the chemical evolution of life, an appreciation of the synthetic and evolutional origins of the first chiral amino acids must first be gained. Given that the amino acids in our universe are likely to have been synthesized in molecular clouds in interstellar space, it is necessary to understand where and how the first synthesis might have occurred. The asymmetry of the original amino acid synthesis was probably the result of exposure to chiral photons in the form of circularly polarized light (CPL), which has been detected in interstellar molecular clouds. This chirality transfer event, from photons to amino acids, has been successfully recreated experimentally and is likely a combination of both asymmetric synthesis and enantioselective photolysis. A series of innovative studies have reported successful simulation of these environments and afforded production of chiral amino acids under realistic circumstellar and interstellar conditions: irradiation of interstellar ice analogues (CO, CO2, NH3, CH3OH, and H2O) with circularly polarized ultraviolet photons at low temperatures does result in enantiomer enriched amino acid structures (up to 1.3% ee). This topical review summarizes current knowledge and recent discoveries about the simulated interstellar environments within which amino acids were probably formed. A synopsis of the COSAC experiment onboard the ESA cometary mission ROSETTA concludes this review: the ROSETTA mission will soft-land on the nucleus of the comet 67P/Churyumov-Gerasimenko in November 2014, anticipating the first in situ detection of asymmetric organic molecules in cometary ices. PMID:22976459

Giri, Chaitanya; Goesmann, Fred; Meinert, Cornelia; Evans, Amanda C; Meierhenrich, Uwe J

2013-01-01

111

Synthesis and anticonvulsant activity of novel bicyclic acidic amino acids  

DEFF Research Database (Denmark)

Bicyclic acidic amino acids (+/-)-6 and (+/-)-7, which are conformationally constrained homologues of glutamic acid, were prepared via a strategy based on a 1,3-dipolar cycloaddition. The new amino acids were tested toward ionotropic and metabotropic glutamate receptor subtypes; both of them behaved as antagonists at mGluR1,5 and as agonists at mGluR2. Furthermore, whereas (+/-)-6 was inactive at all ionotropic glutamate receptors, (+/-)-7 displayed a quite potent antagonism at the NMDA receptors. In the in vivo tests on DBA/2 mice, the compounds displayed an anticonvulsant activity. The interesting pharmacological profile of (+/-)-7 qualifies it as a lead of novel neuroprotective agents.

Conti, Paola; De Amici, Marco

2003-01-01

112

A refined synthesis of enantiomerically pure 2-aminocyclobutanecarboxylic acids.  

Science.gov (United States)

The synthesis of enantiomerically pure 2-aminocyclobutanecarboxylic acids has been refined to improve both the efficiency and the simplicity. These improvements provide a shorter and easier access to the racemic cis-cyclobutane ?-amino acid core. Derivatization of this material with a chiral non-racemic oxazolidin-2-one allows easy diastereoisomeric separation and presents the advantage of allowing the non-destructive cleavage of the chiral auxiliary either by hydrolysis or by ammonolysis, thus providing an efficacious access to N-protected derivatives of all four stereoisomers of Boc-2-aminocyclobutanecarboxylic acid. PMID:21541680

Declerck, Valérie; Aitken, David J

2011-08-01

113

Synthesis of new C?-tetrasubstituted ?-amino acids  

Directory of Open Access Journals (Sweden)

Full Text Available C?-Tetrasubstituted ?-amino acids are important building blocks for the synthesis of peptidemimetics with stabilized secondary structure, because of their ability to rigidify the peptide backbone. Recently our group reported a new class of cyclic C?-tetrasubstituted tetrahydrofuran ?-amino acids prepared from methionine and aromatic aldehydes. We now report the extension of this methodology to aliphatic aldehydes. Although such aldehydes are prone to give aldol products under the reaction conditions used, we were able to obtain the target cyclic amino acids in low to moderate yields and in some cases with good diastereoselectivity.

Andreas A. Grauer

2009-02-01

114

Synthesis of and tautomerism in 3-acyltetramic acids.  

Science.gov (United States)

The synthesis of 3-acyltetramic acids, the substructure of bioactive natural products, via O-acylation of tetramic acids with carboxylic acids followed by acyl migration, has been investigated. This acylation sequence is mediated by N,N'-dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP) and is very sensitive to the nature of the nitrogen substituent (R(1)), the nature of the carboxylic acid (R(2)CO(2)H), and the amount of DMAP. Acylation of N-acyl tetramic acids with an alkyl carboxylic acid using 1.3 equiv of DMAP (with 1.1 equiv of DCC) unexpectedly gave the 3-acyltetramic acid directly as a result of acyl migration induced by excess amounts of DMAP. On the other hand, N-unsubstituted, N-alkyl, and N-acyl tetramic acids with alkyl and aromatic carboxylic acids gave the O-acyl tetramic acids by using only 0.1 equiv of DMAP (with 1.1 equiv of DCC); these could be further rearranged to the acyl product by treatment with excess DMAP. The tautomeric equilibrium of these 3-acyltetramic acids in solution was found to strongly depend on the nitrogen substituent group (R(1)) rather than the 3-acyl group. PMID:21250713

Jeong, Yong-Chul; Moloney, Mark G

2011-03-01

115

Enantioselective total synthesis of pinnaic acid and halichlorine.  

Science.gov (United States)

The enantioselective total synthesis of the bioactive marine natural products pinnaic acid and halichlorine is reported in detail. Our total synthesis features the construction of the five-membered ring and C9 and C13 stereogenic centers through a palladium-catalyzed trimethylenemethane [3+2] cyclization; the installation of the nitrogen atom through a regioselective Beckmann rearrangement of a poorly reactive ketone; the stereoselective cyclization of the spiro ring through a four-step, one-pot hydrogenation-cyclization; and efficient connection of the sterically hindered lower chain through a reduced-pressure cross olefin metathesis reaction. PMID:24136879

Xu, Shu; Unabara, Daisuke; Uemura, Daisuke; Arimoto, Hirokazu

2014-01-01

116

Tormentic acid derivatives: synthesis and apoptotic activity.  

Science.gov (United States)

Several derivatives of tormentic acid have been prepared and tested for their antitumor activity. The dichloroacetate 14 is an excellent antitumor active agent acting by an apoptose inducing pathway as demonstrated by OA/PI staining, DNA laddering experiments as well as by an annexin V binding assay. PMID:22995818

Csuk, René; Siewert, Bianka; Dressel, Christian; Schäfer, Renate

2012-10-01

117

Fatty acid phytyl ester synthesis in chloroplasts of Arabidopsis.  

Science.gov (United States)

During stress or senescence, thylakoid membranes in chloroplasts are disintegrated, and chlorophyll and galactolipid are broken down, resulting in the accumulation of toxic intermediates, i.e., tetrapyrroles, free phytol, and free fatty acids. Chlorophyll degradation has been studied in detail, but the catabolic pathways for phytol and fatty acids remain unclear. A large proportion of phytol and fatty acids is converted into fatty acid phytyl esters and triacylglycerol during stress or senescence in chloroplasts. We isolated two genes (PHYTYL ESTER SYNTHASE1 [PES1] and PES2) of the esterase/lipase/thioesterase family of acyltransferases from Arabidopsis thaliana that are involved in fatty acid phytyl ester synthesis in chloroplasts. The two proteins are highly expressed during senescence and nitrogen deprivation. Heterologous expression in yeast revealed that PES1 and PES2 have phytyl ester synthesis and diacylglycerol acyltransferase activities. The enzymes show broad substrate specificities and can employ acyl-CoAs, acyl carrier proteins, and galactolipids as acyl donors. Double mutant plants (pes1 pes2) grow normally but show reduced phytyl ester and triacylglycerol accumulation. These results demonstrate that PES1 and PES2 are involved in the deposition of free phytol and free fatty acids in the form of phytyl esters in chloroplasts, a process involved in maintaining the integrity of the photosynthetic membrane during abiotic stress and senescence. PMID:22623494

Lippold, Felix; vom Dorp, Katharina; Abraham, Marion; Hölzl, Georg; Wewer, Vera; Yilmaz, Jenny Lindberg; Lager, Ida; Montandon, Cyrille; Besagni, Céline; Kessler, Felix; Stymne, Sten; Dörmann, Peter

2012-05-01

118

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

119

Tracer investigations of the synthesis of 2-chlorethylphosphonic acid  

International Nuclear Information System (INIS)

Using single steps of the synthesis of 2-chloroethylphosphonic acid (I), it is shown that in certain cases accurate information about reaction mechanisms in chemical multicomponent systems can only be obtained with the aid of labelled compounds. Acidolysis of bis-(2-chloroethyl)-2-chloroethylphosphonate (II) with gaseous HCl has been found to proceed in a complex mechanism including rearrangements caused by shifting of ?-chloroethyl groups. Results obtained are discussed and reaction rate constants have been calculated for single steps. Vinylphosphonic acid (III), a by-product of the synthesis of (I), is most probably formed by a preceding thermal dehydrohalogenation of (II), followed by acidolysis of the intermediate bis-(2-chloroethyl)vinylphosphonate. (author)

120

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

 
 
 
 
121

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

122

SYNTHESIS OF HYDROGELS CONTAINING INDOLBUTYRIC ACID AS ROOTING AUXIN  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english 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

123

Synthesis of rosin acid starch catalyzed by lipase.  

Science.gov (United States)

Rosin, an abundant raw material from pine trees, was used as a starting material directly for the synthesis of rosin acid starch. The esterification reaction was catalyzed by lipase (Novozym 435) under mild conditions. Based on single factor experimentation, the optimal esterification conditions were obtained as follows: rosin acid/anhydrous glucose unit in the molar ratio 2:1, reaction time 4 h at 45°C, and 15% of lipase dosage. The degree of substitution (DS) reaches 0.098. Product from esterification of cassava starch with rosin acid was confirmed by FTIR spectroscopy and iodine coloration analysis. Scanning electron microscopy and X-ray diffraction analysis showed that the morphology and crystallinity of the cassava starch were largely destroyed. Thermogravimetric analysis indicated that thermal stability of rosin acid starch decreased compared with native starch. PMID:24977156

Lin, Rihui; Li, He; Long, Han; Su, Jiating; Huang, Wenqin

2014-01-01

124

Induction of phytic acid synthesis by abscisic acid in suspension-cultured cells of rice.  

Science.gov (United States)

A pathway of phytic acid (PA) synthesis in plants has been revealed via investigations of low phytic acid mutants. However, the regulation of this pathway is not well understood because it is difficult to control the environments of cells in the seeds, where PA is mainly synthesized. We modified a rice suspension culture system in order to study the regulation of PA synthesis. Rice cells cultured with abscisic acid (ABA) accumulate PA at higher levels than cells cultured without ABA, and PA accumulation levels increase with ABA concentration. On the other hand, higher concentrations of sucrose or inorganic phosphorus do not affect PA accumulation. Mutations in the genes RINO1, OsMIK, OsIPK1 and OsLPA1 have each been reported to confer low phytic acid phenotypes in seeds. Each of these genes is upregulated in cells cultured with ABA. OsITPK4 and OsITPK6 are upregulated in cells cultured with ABA and in developing seeds. These results suggest that the regulation of PA synthesis is similar between developing seeds and cells in this suspension culture system. This system will be a powerful tool for elucidating the regulation of PA synthesis. PMID:24467907

Matsuno, Koya; Fujimura, Tatsuhito

2014-03-01

125

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

126

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

127

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

2013-01-01

128

Lipase-catalyzed synthesis of fattythioic acids from palm oil.  

Science.gov (United States)

The present work focuses on the synthesis of fattythioic acids (FTAs) by a one-step lipase catalyzed reaction of palm oil with carbonothioic S,S-acid using Lipozyme. The product was characterized using Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance ((1)H NMR) technique and elemental analysis. The effects of various reaction parameters such as reaction time, temperature, amount of enzyme, molar ratio of substrates, and various organic solvents of the reaction system were investigated. The optimum conditions to produce FTAs were respectively, incubation time, 20 h, temperature, 40°C, amount of enzyme, 0.05 g and molar ratio of carbonothioic S,S-acid to palm oil, 5.0:1.0. Hexane was the best solvent for this reaction. The conversion of the products at optimum conditions was around 91%. PMID:21178316

Al-Mulla, Emad A Jaffar

2011-01-01

129

Plasma-chemical modification of the structure and properties of poly(ethylene terephthalate) track membranes  

International Nuclear Information System (INIS)

A process of extraction of the low-molecular products of the synthesis from the poly(ethylene terephthalate) track membranes modified by plasma has been investigated. It is shown that the deposition of a thin polymeric hydrocarbon film by cyclohexane plasma on the membrane surface with preliminary treatment in a plasma of non-polymerizing gases, for example oxygen, allows one to produce membranes possessing a high productivity. Their advantages are much better hydrodynamic properties and a small amount of the low-molecular products of the synthesis extracted by organic solvents

130

Plasma-chemical modification of the structure and properties of poly(ethylene terephthalate) track membranes  

Energy Technology Data Exchange (ETDEWEB)

A process of extraction of the low-molecular products of the synthesis from the poly(ethylene terephthalate) track membranes modified by plasma has been investigated. It is shown that the deposition of a thin polymeric hydrocarbon film by cyclohexane plasma on the membrane surface with preliminary treatment in a plasma of non-polymerizing gases, for example oxygen, allows one to produce membranes possessing a high productivity. Their advantages are much better hydrodynamic properties and a small amount of the low-molecular products of the synthesis extracted by organic solvents.

Kravets, L I [Joint Institute for Nuclear Research, Flerov Laboratory of Nuclear Reactions, 141980 Dubna (Russian Federation); Dmitriev, S N [Joint Institute for Nuclear Research, Flerov Laboratory of Nuclear Reactions, 141980 Dubna (Russian Federation); Dinescu, G [National Institute for Laser, Plasma and Radiation Physics, 77125 Magurele, Bucharest (Romania); Lazea, A [National Institute for Laser, Plasma and Radiation Physics, 77125 Magurele, Bucharest (Romania); Sleptsov, V V [Tsiolkovsky Moscow State Aviation Technological University, 121552 Moscow (Russian Federation); Elinson, V M [Tsiolkovsky Moscow State Aviation Technological University, 121552 Moscow (Russian Federation)

2007-04-15

131

A Novel Approach in Cinnamic Acid Synthesis: Direct Synthesis of Cinnamic Acids from Aromatic Aldehydes and Aliphatic Carboxylic Acids in the Presence of Boron Tribromide  

Directory of Open Access Journals (Sweden)

Full Text Available Cinnamic acids have been prepared in moderate to high yields by a new direct synthesis using aromatic aldehydes and aliphatic carboxylic acids, in the presence of boron tribromide as reagent, 4-dimethylaminopyridine (4-DMAP and pyridine (Py as bases and N-methyl-2-pyrolidinone (NMP as solvent, at reflux (180-190°C for 8-12 hours.

M. Onciu

2005-02-01

132

Senescense: association of synthesis of Acid phosphatase with banana ripening.  

Science.gov (United States)

During ripening of banana (Musa sapientum L., var. Gros Michel or Valery) acid phosphatase activity increases 13-to 26-fold in the precipitate and 2- to 4-fold in the supernatant fraction of tissue homogenates. These increases are closely correlated with the onset and peak of the climacteric. The precipitate enzyme may be extracted with Triton X-100, CaCl(2) or NaCl; about 80% of it is in a 500g precipitate. Studies on effect of tonicity of the grinding medium indicate that the precipitate enzyme is desorbed from membrane or cell wall surfaces, and is not released as a result of lysis of membranes. The development of acid phosphatase during aging of tissue slices is the same as in intact fruit. Short term studies of tissue slices with cycloheximide and actinomycin D indicate that the increase in activity is owed to new enzyme synthesis, which is dependent upon synthesis of RNA. The possible effects of the increase in acid phosphatase on ripening are discussed. PMID:16657436

De Leo, P; Sacher, J A

1970-08-01

133

Depolymerization of polyethylene terephthalate in supercritical methanol  

Science.gov (United States)

The degradation of polyethylene terephthalate (PET) in supercritical methanol was investigated with the aim of developing a process for chemical recycling of waste plastics. A batch reactor was used at temperatures of 573-623 K under an estimated pressure of 20 MPa for a reaction time of 2-120 min. PET was decomposed to its monomers, dimethyl terephthalate and ethylene glycol, by methanolysis in supercritical methanol. The reaction products were analysed using size-exclusion chromatography, gas chromatography-mass spectrometry, and reversed-phase liquid chromatography. The molecular weight distribution of the products was obtained as a function of reaction time. The yields of monomer components of the decomposition products including by-products were measured. Continuous kinetics analysis was performed on the experimental data.

Goto, Motonobu; Koyamoto, Hiroshi; Kodama, Akio; Hirose, Tsutomu; Nagaoka, Shoji

2002-11-01

134

Lipid synthesis in lactation: diet and the fatty acid switch.  

Science.gov (United States)

The lipid component of milk provides the critical nutritional source for generating both energy and essential nutrients to the growth of the newborn. Three types of substrate are utilized to synthesize milk triacylglycerides (TAG): dietary fat, fatty acids mobilized from adipose tissue stores, and lipids synthesized de novo synthesis from glucose and other dietary precursors, a process often referred to as de novo lipogenesis. The utilization of these various sources for TAG synthesis by the mammary epithelial cells is influenced by both the stage of lactation and the diet. From studies of gene expression in FVB mice, we observed that genes for beta-oxidation of fatty acids are downregulated along with the expression of Acyl-CoA thioesterase 1 (ACOT1). As a control mechanism we propose that during pregnancy ACOT1 provides a supply of cytoplasmic free fatty acids which increase the activation of PPARgamma. Ligand-induced activation of the PPAR/RXR transcription factor complex by free fatty acids, upregulates expression of genes required for beta-oxidation of fatty acids. The fall in ACOTs at secretory activation may facilitate the switch to lipogenesis perhaps mediated by activation of the LXR/RXR transcription factor complex. The response to changes in the supply of dietary lipids, on the other hand, is likely to be mediated by SREBP1, possibly acting through modulation of Spot 14. Stability of SREBP1 may be enhanced by a significant increase in Akt at secretory activation. These regulatory pathways may be critical to the production of milk with a balanced TAG composition to support neonatal development of the newborn. PMID:18027074

Rudolph, Michael C; Neville, Margaret C; Anderson, Steven M

2007-12-01

135

An improved synthesis of [15N] 16-Doxyl stearic acid  

International Nuclear Information System (INIS)

An improved method for the synthesis of [15N] 16-Doxyl stearate, a fatty-acid spin label, is reported. The method requires only one mole of [15N] 2-amino-2-methyl propanol per mole of methyl keto stearate with an overall yield of about 50%. In contrast, the previous method produced only 1-3% yield. The great improvement in yield was achieved mainly through the reduction of reaction volume which increases the reaction rate by the law of mass action. (author)

136

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

137

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

138

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

139

Synthesis of 14C-labeled perfluorooctanoic and perfluorodecanoic acids; Purification of perfluorodecanoic acid  

Energy Technology Data Exchange (ETDEWEB)

Perfluorooctanoic and -decanoic acids are representative of a series of perfluorinated acids that have been used for a variety of industrial purposes primarily due to their surfactant properties. The toxicity of these compounds is being investigated in a number of laboratories. 14C-labeled materials would be useful in these studies but are not commercially available. Johncock prepared unlabeled PFOA in low yield by carbonation of the unstable perfluoroheptyllithium at -90 degrees Centigrade. We anticipated several problems in applying this procedure to the synthesis of the 14C-labeled material. Johncock's procedure was run on a fairly large scale (10 mmol) with excess CO2.

Reich, I.L.; Reich, H.J.; Menahan, L.A.; Peterson, R.E.

1987-01-01

140

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

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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

 
 
 
 
141

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

142

Ascorbic Acid Efficiently Enhances Neuronal Synthesis of Norepinephrine from Dopamine  

Science.gov (United States)

Ascorbic acid enhances synthesis of norepinephrine from dopamine in adrenal chromaffin cells by serving as a co-factor for chromaffin granule dopamine ?-hydroxylase (D?H). However, there is controversy regarding in situ kinetics of the ascorbate effect in chromaffin cells, as well as whether they apply to neuronal cells. In this study we evaluated the stimulation of norepinephrine synthesis from dopamine in cultured SH-SY5Y neuroblastoma cells. These cells contained neither ascorbate nor norepinephrine in culture, but when provided with dopamine, they generated intracellular norepinephrine at rates that were stimulated several fold by intracellular ascorbate. Ascorbate-induced increases in norepinephrine synthesis in dopamine-treated cells were linear over 60 minutes, despite saturation of intracellular ascorbate. Norepinephrine accumulation after 60 minutes of incubation with 100 ?M dopamine was half-maximal at intracellular ascorbate concentrations of 0.2 – 0.5 mM, which fits well with the literature Km for ascorbate of D?H using dopamine as a substrate. Moreover, these ascorbate concentrations were generated by initial extracellular ascorbate concentrations of less than 25 ?M due to concentrative accumulation by the ascorbate transporter. Treatment with 100 ?M dopamine acutely increased cellular superoxide generation, which was prevented by ascorbate loading, but associated with a decrease in intracellular ascorbate when the latter was present at concentrations under 1 mM. These results show that ascorbate promptly enhances norepinephrine synthesis from dopamine by neuronal cells, that it does so at physiologic intracellular concentrations in accord with the kinetics of D?H, and that it both protects cells from superoxide and by providing electrons to D?H. PMID:23022576

May, James M.; Qu, Zhi-chao; Nazarewicz, Rafal; Dikalov, Sergey

2012-01-01

143

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

144

Decrease in calcium concentration triggers neuronal retinoic acid synthesis during homeostatic synaptic plasticity  

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Blockade of synaptic activity induces homeostatic plasticity, in part by stimulating synthesis of all-trans retinoic acid (RA), which in turn increases AMPA receptor synthesis. However, the synaptic signal that triggers RA synthesis remained unknown. Using multiple activity-blockade protocols that induce homeostatic synaptic plasticity, here we show that RA synthesis is activated whenever postsynaptic Ca2+-entry is significantly decreased, and that RA is required for up-regulation of synaptic...

Wang, Hui-li; Zhang, Zhenjie; Hintze, Maik; Chen, Lu

2011-01-01

145

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

Science.gov (United States)

A process of preparing an acid addition salt of delta-aminolevulinc acid comprising: a) dissolving a lower alkyl 5-bromolevulinate and hexamethylenetetramine in a solvent selected from the group consisting of water, ethyl acetate, chloroform, acetone, ethanol, tetrahydrofuran and acetonitrile, to form a quaternary ammonium salt of the lower alkyl 5-bromolevulinate; and b) hydrolyzing the quaternary ammonium salt with an inorganic acid to form an acid addition salt of delta-aminolevulinic acid.

Moens, Luc (Lakewood, CO)

2003-06-24

146

One-step synthesis of 12-ketoursodeoxycholic acid from dehydrocholic acid using a multienzymatic system.  

Science.gov (United States)

12-ketoursodeoxycholic acid (12-keto-UDCA) is a key intermediate for the synthesis of ursodeoxycholic acid (UDCA), an important therapeutic agent for non-surgical treatment of human cholesterol gallstones and various liver diseases. The goal of this study is to develop a new enzymatic route for the synthesis 12-keto-UDCA based on a combination of NADPH-dependent 7?-hydroxysteroid dehydrogenase (7?-HSDH, EC 1.1.1.201) and NADH-dependent 3?-hydroxysteroid dehydrogenase (3?-HSDH, EC 1.1.1.50). In the presence of NADPH and NADH, the combination of these enzymes has the capacity to reduce the 3-carbonyl- and 7-carbonyl-groups of dehydrocholic acid (DHCA), forming 12-keto-UDCA in a single step. For cofactor regeneration, an engineered formate dehydrogenase, which is able to regenerate NADPH and NADH simultaneously, was used. All three enzymes were overexpressed in an engineered expression host Escherichia coli BL21(DE3)?7?-HSDH devoid of 7?-hydroxysteroid dehydrogenase, an enzyme indigenous to E. coli, in order to avoid formation of the undesired by-product 12-chenodeoxycholic acid in the reaction mixture. The stability of enzymes and reaction conditions such as pH value and substrate concentration were evaluated. No significant loss of activity was observed after 5 days under reaction condition. Under the optimal condition (10 mM of DHCA and pH 6), 99 % formation of 12-keto-UDCA with 91 % yield was observed. PMID:22899496

Liu, Luo; Braun, Michael; Gebhardt, Gabi; Weuster-Botz, Dirk; Gross, Ralf; Schmid, Rolf D

2013-01-01

147

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

148

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

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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

149

Synthesis of the isofatty acid 13-methyl-tetradecanoic acid and its triglyceride  

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Full Text Available A new and more convenient synthesis of the isofatty acid 13-methyl-tetradecanoic acid and its triglyceride is described here. This isofatty acid is prepared through elongation of the undecanoic acid chain with isobutyraldehyde according to Wittig by the reaction between bromo-undecanoic acid ethyl ester-triphenylphosphonium salt and sodium methoxide followed by the addition of isobutyraldehyde. Its triglyceride is formed by the esterification of the free isofatty acid with glycerin without catalyst. Its purity was over 99% after high refining over activated silica gel. Total yield was estimated to be 22,8%.

Una nueva y práctica síntesis del ácido graso iso-13-metil- tetradecanoico y sus triglicéridos se describe aquí. Este iso- ácido graso se prepara a través de la elongación de la cadena del ácido undecanoico con isobutiraldehido según Wittig por reacción entre la sal de bromuro de undecanoico etil-éster trifenilfosfonio y metilato sódio seguido de la adición de isobutiraldehido. Su triglicérido está formado por la esterificación del iso ácido graso libre con glicerina sin catalizador. Su pureza es superior al 99%, después de una alta refinación sobre gel de sílice activado. El rendimiento total se estimó en el 22,8%.

Zlatanos, S.

2011-12-01

150

Injury-induced inhibition of small intestinal protein and nucleic acid synthesis  

International Nuclear Information System (INIS)

Small intestinal mucosal weight and nutrient absorption are significantly diminished early after cutaneous thermal injuries. Because these intestinal properties are highly dependent on rates of nucleic acid and protein synthesis, in vivo incorporation of thymidine, uridine, and leucine into small intestinal deoxyribonucleic acid, ribonucleic acid, and proteins were measured. Deoxyribonucleic acid synthesis was markedly decreased with the lowest thymidine incorporation in the jejunum (p less than 0.01); these findings were confirmed by autoradiographic identification of radiolabeled nuclei in the intestinal crypts. Protein synthesis was decreased by 6 h postinjury (p less than 0.01) but had returned to normal by 48 h. Consistent with a decreased rate of protein synthesis, ribonucleic acid synthesis was also decreased 18 h postinjury (p less than 0.01). These decreased deoxyribonucleic acid, ribonucleic acid, and protein synthesis rates are not likely a result of ischemia because in other studies of this injury model, intestinal blood flow was not significantly changed by the burn injury. Potentially, factors initiating the acute inflammatory reaction may directly inhibit nucleic acid and protein synthesis and lead to alterations in nutrient absorption and intestinal barrier function after injury

151

Injury-induced inhibition of small intestinal protein and nucleic acid synthesis  

Energy Technology Data Exchange (ETDEWEB)

Small intestinal mucosal weight and nutrient absorption are significantly diminished early after cutaneous thermal injuries. Because these intestinal properties are highly dependent on rates of nucleic acid and protein synthesis, in vivo incorporation of thymidine, uridine, and leucine into small intestinal deoxyribonucleic acid, ribonucleic acid, and proteins were measured. Deoxyribonucleic acid synthesis was markedly decreased with the lowest thymidine incorporation in the jejunum (p less than 0.01); these findings were confirmed by autoradiographic identification of radiolabeled nuclei in the intestinal crypts. Protein synthesis was decreased by 6 h postinjury (p less than 0.01) but had returned to normal by 48 h. Consistent with a decreased rate of protein synthesis, ribonucleic acid synthesis was also decreased 18 h postinjury (p less than 0.01). These decreased deoxyribonucleic acid, ribonucleic acid, and protein synthesis rates are not likely a result of ischemia because in other studies of this injury model, intestinal blood flow was not significantly changed by the burn injury. Potentially, factors initiating the acute inflammatory reaction may directly inhibit nucleic acid and protein synthesis and lead to alterations in nutrient absorption and intestinal barrier function after injury.

Carter, E.A.; Hatz, R.A.; Yarmush, M.L.; Tompkins, R.G. (Massachusetts General Hospital, Boston (USA))

1990-06-01

152

SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF AMIDE DERIVATIVES FROM ACRYLOPIMARIC ACID  

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Full Text Available This paper reports on the synthesis of a series of amide derivatives from acrylopimaric acid (APA. The derivatives contained aromatic groups and were characterized by IR, 1HNMR, MS, and elemental analysis. The antibacterial activity of the derivatives against Gram-negative bacteria and Gram-positive bacteria were also investigated. When compared with the other derivatives, compounds 3a and 3f showed much higher activity against Escherichia coli (Gram-negative bacteria with inhibition zones of 5 mm and 5.5 mm, respectively. Structure-activity relationship analysis revealed that ortho-substituted phenyl derivatives and meta-substituted phenyl derivatives exhibited higher activity than the para-substituted derivatives. Meanwhile, the halogen-substituted compounds did not show visible antibacterial activity compared with other compounds, which may have been caused by the lower electron density of the halogen-substituted phenyl rings.

Jian Li,

2012-02-01

153

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

154

Synthesis and pharmacokinetic profile of rhein- boswellic acid conjugate.  

Science.gov (United States)

Rhein, an active metabolite of diacerein, down-regulates the gene-expression and production of pro-matrix metalloproteinases and up-regulates the tissue inhibitors of metalloproteinase-1 production. The therapeutic effects of diacerein on osteoarthritis are, at least in part, due to the chondroprotective effect of rhein. Boswellic acid is a specific, non-redox inhibitor of leukotriene synthesis. It is claimed to possess good anti-inflammatory, anti-arthritic, analgesic, and anti-ulcer activities. It prevents the destruction of articular cartilage by decreasing degradation of glycosaminoglycans. Therefore, rhein and boswellic acid were linked chemically through a bioreversible ester linkage to synthesize their mutual prodrug by reported procedure. In vitro release profile of this prodrug was extensively studied in aqueous buffers of varied pH, upper GIT homogenates and 80% human plasma. In vivo release studies were undertaken in blood, urine and feces of rats. The prodrug was stable in HCl buffer (pH 1.2) and stomach homogenates of rats. However; in phosphate buffer (pH 7.4) and in intestinal homogenates the prodrug exhibited 91% and 96% release of rhein and 27.5% and 38% release of boswellic acid respectively over a period of 6h following first order kinetics. In 80% human plasma (in vitro) and rat blood (in vivo) also 96.35% and 91% release of rhein and 78% and 86.41% release of boswellic acid respectively was observed. The 24 h pooled samples of rat urine revealed presence of 6.2% intact prodrug, 7.1% of rhein and 8.9% of boswellic acid indicating their renal excretion. Samples of rat feces pooled over a period of 24 h showed absence of rhein and presence of 3.1% of intact boswellic acid and 4.6% of boswellic acid emphasizing their intestinal excretion. The in vivo release kinetics of prodrug in rat clearly indicated activation of prodrug to be occurring in blood, being catalyzed by the weak alkaline pH of blood (7.4) in combination with esterases present therein. PMID:23107483

Suneela, Dhaneshwar; Dipmala, Patil

2012-12-15

155

Hepatocyte-hepatoma cell hybrids. Characterization and demonstration of bile acid synthesis.  

Science.gov (United States)

Hybrids were created by fusion of primary rat hepatocytes with well-differentiated Reuber H35 rat hepatoma cells. Seventeen hybrids were screened for bile acid synthesis using [26-14C]cholesterol. As [26-14C]cholesterol was converted to bile acid, 14CO2 was released. Using this assay, four hybrids (8B, 12C, 13C, and 13D) were identified which synthesized bile acid. These four hybrids also incorporated [14C]taurine into bile acid. Bile acids were identified by capillary gas chromatography/mass spectrometry, and their rates of synthesis were quantitated by isotope dilution. Reuber H35 cells synthesized little or no bile acid. However, hybrids 8B, 12C, 13C, and 13D synthesized chenodeoxycholic acid, alpha-muricholic acid, and cholic acid and secreted them into the media. The rates of synthesis of individual bile acids varied among these hybrids. For example, the relative percentage of cholic acid ranged from 11.1% (hybrid 8B) to 50.4% (hybrid 13C). The bile acids synthesized and secreted by the most active hybrid, 12C, were greater than 93% conjugated. In summary, hybrids were created that retain the capacity to synthesize, conjugate, and secrete three major rat bile acid species. Such hybrids are unique model systems that will allow the study of the biochemical and genetic regulation of bile acid synthesis. PMID:3949804

Polokoff, M A; Everson, G T

1986-03-25

156

Synthesis and photochromic property of nanosized amino acid polyoxometalate compounds  

Science.gov (United States)

A series of novel nanosized amino acid-polyoxometalate compounds were successfully synthesized using a low temperature solid-state chemical reaction method. Their compositions, structures, morphologies, photochromic properties were characterized by ICP-AES/MS, TG/DTA, FTIR, XRD, SEM and UV-Vis diffuse reflectance spectra (DRS), respectively. The elemental analysis results showed that the compounds ((HThr)7PMo12O42•4H2O, (HTyr)7PMo12O42Â.5H2O, (HSer)7PMo12O42•5H2O and (HGlu)7PMo12O42•4H2O) were obtained. The analyses of the TG/DTA, XRD and FTIR confirmed that the four compounds are new phases different from the corresponding reactants and they are composed of the polyoxometalate anions and the corresponding protonated amino acids, respectively. Observation of the SEM revealed that the particle shape (e.g. (HThr)7PMo12O42Â.4H2O nanoplates, (HTyr)7PMo12O42•5H2O nanorods, (HSer)7PMo12O42•5H2O and (HGlu)7PMo12O42•4H2O nanoparticles) depended strongly on the structures of amino acids. This implied that the amino acids can play a structural template agent role in synthesis of the Silverton-type polyoxometalate compounds. After irradiated with ultraviolet light, these samples all exhibited photochromism. Their photochromic mechanism may be explained based on Yamase's photochromic model. These photochromic compounds could be applied to the field of photosensitive materials.

Sun, Dehui; Zhang, Jilin; Ren, Huijuan; Cui, Zhenfeng

2009-07-01

157

Enzymatic synthesis and application of fatty acid ascorbyl esters  

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Full Text Available Fatty acid ascorbyl esters are liposoluble substances that possess good antioxidative properties. These compounds could be synthesized by using various acyl donors for acylation of vitamin C in reaction catalyzed by chemical means or lipases. Enzymatic process is preferred since it is regioselective, performed under mild reaction conditions, with the obtained product being environmentally friendly. Polar organic solvents, ionic liquids, and supercritical fluids has been successfully used as a reaction medium, since commonly used solvents with high Log P values are inapplicable due to ascorbic acid high polarity. Acylation of vitamin C using fatty acids, their methyl-, ethyl-, and vinyl esters, as well as triglycerides has been performed, whereas application of the activated acyl donors enabled higher molar conversions. In each case, majority of authors reported that using excessive amount of the acyl donor had positive effect on yield of product. Furthermore, several strategies have been employed for shifting the equilibrium towards the product by water content control. These include adjusting the initial water activity by pre-equilibration of reaction mixture, enzyme preparation with water vapor of saturated salt solutions, and the removal of formed water by the addition of molecular sieves or salt hydrate pairs. The aim of this article is to provide a brief overview of the procedures described so far for the lipase-catalyzed synthesis of fatty acid ascorbyl esters with emphasis on the potential application in food, cosmetics, and pharmaceutics. Furthermore, it has been pointed out that the main obstacles for process commercialization are long reaction times, lack of adequate purification methods, and high costs of lipases. Thus, future challenges in this area are testing new catalysts, developing continuous processes for esters production, finding cheaper acyl donors and reaction mediums, as well as identifying standard procedures for purification of products which will not require consumption of large amounts of non-biocompatible organic solvents.

Stojanovi? Marija M.

2013-01-01

158

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

159

Role of fatty-acid synthesis in dendritic cell generation and function.  

Science.gov (United States)

Dendritic cells (DC) are professional APCs that regulate innate and adaptive immunity. The role of fatty-acid synthesis in DC development and function is uncertain. We found that blockade of fatty-acid synthesis markedly decreases dendropoiesis in the liver and in primary and secondary lymphoid organs in mice. Human DC development from PBMC precursors was also diminished by blockade of fatty-acid synthesis. This was associated with higher rates of apoptosis in precursor cells and increased expression of cleaved caspase-3 and BCL-xL and downregulation of cyclin B1. Further, blockade of fatty-acid synthesis decreased DC expression of MHC class II, ICAM-1, B7-1, and B7-2 but increased their production of selected proinflammatory cytokines including IL-12 and MCP-1. Accordingly, inhibition of fatty-acid synthesis enhanced DC capacity to activate allogeneic as well as Ag-restricted CD4(+) and CD8(+) T cells and induce CTL responses. Further, blockade of fatty-acid synthesis increased DC expression of Notch ligands and enhanced their ability to activate NK cell immune phenotype and IFN-? production. Because endoplasmic reticulum (ER) stress can augment the immunogenic function of APC, we postulated that this may account for the higher DC immunogenicity. We found that inhibition of fatty-acid synthesis resulted in elevated expression of numerous markers of ER stress in humans and mice and was associated with increased MAPK and Akt signaling. Further, lowering ER stress by 4-phenylbutyrate mitigated the enhanced immune stimulation associated with fatty-acid synthesis blockade. Our findings elucidate the role of fatty-acid synthesis in DC development and function and have implications to the design of DC vaccines for immunotherapy. PMID:23536633

Rehman, Adeel; Hemmert, Keith C; Ochi, Atsuo; Jamal, Mohsin; Henning, Justin R; Barilla, Rocky; Quesada, Juan P; Zambirinis, Constantinos P; Tang, Kerry; Ego-Osuala, Melvin; Rao, Raghavendra S; Greco, Stephanie; Deutsch, Michael; Narayan, Suchithra; Pachter, H Leon; Graffeo, Christopher S; Acehan, Devrim; Miller, George

2013-05-01

160

Efficient and scalable one-pot synthesis of 2,4-dienols from cycloalkenones: optimized total synthesis of valerenic acid.  

Science.gov (United States)

A mild and selective one-pot procedure to provide 2,4-dienols from simple cycloalkenones in high yields is described. This transformation is based on the in situ formation of acid-labile allylic alcohols, which on treatment with trifluoroacetic acid undergo a formal [1,3]-hydroxy migration to form diastereo- and enantiomerically enriched 2,4-dienols. The usefulness of this protocol is demonstrated in a short synthesis of valerenic acid. PMID:21894886

Ramharter, Juergen; Mulzer, Johann

2011-10-01

 
 
 
 
161

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.

Hansen, Heinz Johs. Max

1972-01-01

162

Influence of diet on in vitro and in vivo rates of fatty acid synthesis in coho salmon [Oncorhynchus kisutch (Walbaum)].  

Science.gov (United States)

The site and the influence of diet on fatty acid synthesis in juvenile coho salmon were investigated. Tritiated water was used to obtain estimates of the rates of fatty acid synthesis. Liver slices and mesenteric glucose and tritiated water. The rate of fatty acid synthesis averaged 1172 +/- 126 and 40 +/- 8 nmoles tritium incorporated into fatty acids per 2 hours per 100 mg of liver and adipose tissue, respectively. The pattern of [1-14C]acetate incorporation into fatty acids in the liver slices indicated that de novo fatty acid synthesis, rather than chain elongation, was occurring. In vivo rates of fatty acid synthesis in liver were approximately linear for 30 minutes. In vivo rates of fatty acid synthesis averaged 244 +/- 14 and 44 +/- 11 dpm of tritium incorporated into fatty acids per 20 minutes per 100 mg of liver and adipose tissue, respectively. Consumption of a high-fat diet or fasting for 2 days decreased the in vitro and in vivo rates of fatty acid synthesis in fish liver. Refeeding fasted (48 hours) fish with a high-carbohydrate diet for 4 hours increased the rate of hepatic fatty acid synthesis. The major site of fatty acid synthesis in coho salmon appears to be the liver, and dietary alterations influence the rate of fatty acid synthesis in the liver. PMID:894363

Lin, H; Romsos, D R; Tack, P I; Leveille, G A

1977-09-01

163

Synthesis and properties of carbohydrate-phosphate backbone-modified oligonucleotide analogues and nucleic acid mimetics  

Energy Technology Data Exchange (ETDEWEB)

Advances in the synthesis of oligo(deoxy)ribonucleotide analogues and nucleic acid mimetics made in the last decade are summarized. Attention is focused on new methods for the synthesis of derivatives with a modified ribose-phosphate backbone (phosphorothioate, boranophosphate, and nucleoside phosphonate derivatives) and derivatives devoid of the phosphate group. Among nucleic acid mimetics, conformationally restricted modified peptide nucleic acids, including those bearing a negative or positive charge, and morpholino oligomers are considered. Advantages and drawbacks of the main types of analogues as regards the complexity of the synthesis and the possibility of their application as antisense agents or reagents for hybridization analysis are compared.

Abramova, Tatyana V; Silnikov, Vladimir N [Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences (Russian Federation)

2011-05-31

164

Ceramide synthesis from free fatty acids in rat brain: function of NADPH and substrate specificity  

Energy Technology Data Exchange (ETDEWEB)

At the subcellular level, the synthesis of ceramide from free lignoceric acid and sphingosine in brain required reconstituted enzyme system (particulate fraction, heat-stable and heat-labile factors) and pyridine nucleotide (NADPH). The mitochondrial electron transfer inhibitors (KCN and antimycin A), energy uncouplers (oligomycin and 2,4-dinitrophenol), and carboxyatractyloside, which prevents the transport of ATP and ADP through the mitochondrial wall, inhibit the synthesis of ceramide in the presence of NADPH but have very little effect in the presence of ATP. Similar to the synthesis of ceramide, the synthesis of ATP from NADPH and NADH by the particulate fraction also required cytoplasmic factors (heat-stable and heat-labile factors). Moreover, ATP, but not its analog (AMP-CH2-P-O-P), can replace NADPH, thus suggesting that the function of the pyridine nucleotide is to provide ATP for the synthesis of ceramide. The cytoplasmic factors were not required for the synthesis of ceramide in the presence of ATP. The maximum velocity for synthesis of ceramide from free fatty acids of different chain lengths (C16-C26) was bimodal, with maxima around stearic acid (C18) and behenic acid (C22). The relative rate of synthesis of ceramide parallels the relative distribution of these fatty acids in brain cerebrosides and sulfatides.

Singh, I.

1983-06-01

165

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

166

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

167

Versatile synthesis of the C3-C14 domain of 7-deoxyokadaic acid.  

Science.gov (United States)

Described is a flexible synthesis of the C3-C14 domain of 7-deoxyokadaic acid that is amenable to facile structural diversification. Treatment of ynone 10 under acidic conditions led to net bis-conjugate addition of the latent diol to give the thermodynamically favored spiroketal 27, a versatile intermediate, en route to 7-deoxyokadaic acid and analogs. PMID:19072579

Trygstad, Timothy M; Pang, Yucheng; Forsyth, Craig J

2009-01-16

168

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

169

Thioacetic acid/NaSH-mediated synthesis of N-protected amino thioacids and their utility in peptide synthesis.  

Science.gov (United States)

Thioacids are recently gaining momentum due to their versatile reactivity. The reactivity of thioacids has been widely explored in the selective amide/peptide bond formation. Thioacids are generally synthesized from the reaction between activated carboxylic acids such as acid chlorides, active esters, etc., and Na2S, H2S, or NaSH. We sought to investigate whether the versatile reactivity of the thioacids can be tuned for the conversion of carboxylic acids into corresponding thioacids in the presence of NaSH. Herein, we report that thioacetic acid- and NaSH-mediated synthesis of N-protected amino thioacids from the corresponding N-protected amino acids, oxidative dimerization of thioacids, crystal conformations of thioacid oxidative dimers, and the utility of thioacids and oxidative dimers in peptide synthesis. Our results suggest that peptides can be synthesized without using standard coupling agents. PMID:24548175

Mali, Sachitanand M; Gopi, Hosahudya N

2014-03-21

170

Differential effects of arachidonic acid and docosahexaenoic acid on cell biology and osteoprotegerin synthesis in osteoblast-like cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The purpose of the study was to elucidate the mechanisms by which polyunsaturated fatty acids (PUFAs) prevent bone loss. MG-63 human osteoblasts and MC3T3-E1 murine osteoblasts were exposed to the n-6 PUFA arachidonic acid (AA) and the n-3 PUFA docosahexaenoic acid (DHA) as well as oestrogen (E2) and parathyroid hormone (PTH) and the effects thereof tested on a variety of biological parameters characteristic of osteoblasts. These parameters included prostaglandin E2 (PGE2) synthesi...

Coetzee, Magdalena

2006-01-01

171

Bile acid metabolism in cirrhosis. VIII. Quantitative evaluation of bile acid synthesis from [7 beta-3H]7 alpha-hydroxycholesterol and [G-3H]26-hydroxycholesterol  

International Nuclear Information System (INIS)

In order to evaluate more definitively the observed aberrations in the synthesis of cholic and chenodeoxycholic acids in patients with advanced cirrhosis, two bile acid biosynthesis pathways were examined by determining the efficiency of conversion of [3H]7 alpha-hydroxycholesterol and [3H] 26-hydroxycholesterol to primary bile acids. Bile acid kinetics were determined by administration of [14C]cholic and [14C]chenodeoxycholic acids. Cholic acid synthesis in cirrhotic patients was markedly depressed (170 vs 927 ?moles per day)( while chenodeoxycholic acid synthesis was reduced to a much lesser degree (227 vs 550 ?moles per day). The administration of [3H]7 alpha-hydroxycholesterol allowed for an evaluation of the major pathway of bile acid synthesis via the 7 alpha-hydroxylation of cholesterol. This compound was efficiently incorporated into primary bile acids by the two normal subjects (88 and 100%) and two cirrhotic patients (77 and 91%). However, the recovery of the label in cholic acid was slightly less in cirrhotic patients than in normal subjects. [3H]26-hydroxycholesterol was administered to ascertain the contribution of the 26-hydroxylation pathway to bile acid synthesis. All study subjects showed poor conversion (9 to 22%) of this intermediate into bile acids. The results of this study suggest that a major block in the bile acid synthesis pathway in cirrhosis is at the level of 7 alpha-hydroxylation of cholesterol (impairment of 7 alpha-hydroxylase) and/or in the feedback triggering mechanism regulating bile acid synthesis. The data also suggest that the 26-hydroxylation pathway in normal subjects and patients with cirrhosis is a minor contributor to synthesis of the primary bile acids. Therefore, the relative sparing of chenodeoxycholic acid synthesis observed in cirrhotic patients is not due to preferential synthesis of this bile acid via the 26-hydroxylation pathway

172

Synthesis of D-(-)-[1,7-13C2]shikimic acid  

International Nuclear Information System (INIS)

The chemical synthesis of 99% enriched D(-)-[1,7-13C2]shikimic acid from [1,2-13C2]acetate in 25% overall yield is described. A two-carbon phosphonate synthon was prepared from [1,2-13C2]acetate and used in the shikimate synthesis of Fleet et al. (author)

173

Synthesis of [3H] aminocyclopropane carboxylic acid (ACC) as a ligand for the glycine B receptor  

International Nuclear Information System (INIS)

The synthesis of [3H]Aminocyclopropane carboxylic acid at high specific activity and high purity is described. The compound has been developed as a specific ligand for the Glycine-B binding site. (author)

174

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

175

Synthesis of Phosphatidylcholine Analogues Derived from Glyceric Acid: a New Class of Biologically Active Phospholipid Compounds  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Synthesis of a new class of phosphatidylcholine analogues derived from glyceric acid is reported for spectroscopic studies of phospholipases and conformation of phospholipid side-chains in biological membranes, using fluorescence resonance energy transfer (FRET) techniques.

Rosseto, Renato; Tcacenco, Celize M.; Ranganathan, Radha; Hajdu, Joseph

2008-01-01

176

The synthesis and investigation of some bile acids derivatives on the base of 3?, 7?, 12?-three hydro oxi cholane acids  

International Nuclear Information System (INIS)

In this chapter of book authors investigated the synthesis of some bile acids derivatives on the base of 3?, 7?, 12?-three hydro oxi cholane acids. As a result of this investigation worked up preparative methods of synthesis of glycerin ethers of chenodeoxycholic acid

177

Synthesis of crambescin B carboxylic acid, a potent inhibitor of voltage-gated sodium channels.  

Science.gov (United States)

The stereocontrolled synthesis of a racemic carboxylic acid of crambescin B, a marine alkaloid, is described. The synthesis features two highly stereoselective reactions: (I) palladium-catalyzed hydroxymethylation of an alkynyl aziridine having an N-guanidino group and (II) cascade bromocyclization providing a spiro-hemiaminal structure. The cell-based colorimetric assay showed that the synthesized carboxylic acid exhibited a potent inhibitory activity on voltage-gated sodium channels. PMID:24216693

Nakazaki, Atsuo; Ishikawa, Yuki; Sawayama, Yusuke; Yotsu-Yamashita, Mari; Nishikawa, Toshio

2014-01-01

178

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)

179

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

Directory of Open Access Journals (Sweden)

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

180

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

 
 
 
 
181

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

182

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

183

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

Directory of Open Access Journals (Sweden)

Full Text Available 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-amides 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.

Joanna Gajowy

2014-10-01

184

Abc Amino Acids: Design, Synthesis, and Properties of New Photoelastic Amino Acids  

Energy Technology Data Exchange (ETDEWEB)

Photoisomerizable amino acids provide a direct avenue to the experimental manipulation of bioactive polypeptides, potentially allowing real-time, remote control of biological systems and enabling useful applications in nanobiotechnology. Herein, we report a new class of photoisomerizable amino acids intended to cause pronounced expansion and contraction in the polypeptide backbone, i.e., to be photoelastic. These compounds, termed Abc amino acids, employ a photoisomerizable azobiphenyl chromophore to control the relative disposition of aminomethyl and carboxyl substituents. Molecular modeling of nine Abc isomers led to the identification of one with particularly attractive properties, including the ability to induce contractions up to 13A in the backbone upon transa?cis photoisomerization. This isomer, designated mpAbc, has substituents at meta and para positions on the inner (azo-linked) and outer rings, respectively. An efficient synthesis of Fmoc-protected mpAbc was executed in which the biaryl components were formed via Suzuki couplings and the azo linkage was formed via amine/nitroso condensation; protected forms of three other Abc isomers were prepared similarly. A decapeptide incorporating mpAbc was synthesized by conventional solid-phase methods and displayed characteristic azobenzene photochemical behavior with optimal conversion to the cis isomer at 360 nm and a thermal cisa?trans half life of 100 min. at 80 AoC.

Standaert, Robert F [ORNL; Park, Dr Seung Bum [Seoul National University

2006-01-01

185

High yield synthesis of some phosphonic acid derivatives as surface tethers for energy harvesting technologies  

Directory of Open Access Journals (Sweden)

Full Text Available Efficient synthesis of novel 6-(2-bromo-2-methyl propanoyloxyhexyl phosphonic acid, dodecane di-phosphonic acid, 6-(thiophene-3-carbonyloxyhexyl phosphonic acid, octadecyl phosphonic acid and such other derivatives are reported here. These derivatives have a potential application as tethers to nanoparticle surfaces that can promote efficient electron transfer process in solar energy conversion. DOI: http://dx.doi.org/10.4314/bcse.v28i1.17

A. Mungalimane

2014-01-01

186

Crystal structure of Spot 14, a modulator of fatty acid synthesis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Spot 14 (S14) is a protein that is abundantly expressed in lipogenic tissues and is regulated in a manner similar to other enzymes involved in fatty acid synthesis. Deletion of S14 in mice decreased lipid synthesis in lactating mammary tissue, but the mechanism of S14’s action is unknown. Here we present the crystal structure of S14 to 2.65 ? and biochemical data showing that S14 can form heterodimers with MIG12. MIG12 modulates fatty acid synthesis by inducing the polymerization and act...

Colbert, Christopher L.; Kim, Chai-wan; Moon, Young-ah; Henry, Lisa; Palnitkar, Maya; Mckean, William B.; Fitzgerald, Kevin; Deisenhofer, Johann; Horton, Jay D.; Kwon, Hyock Joo

2010-01-01

187

Chemical modification and functionalisation of poly(ethylene terephthalate) fiber  

Energy Technology Data Exchange (ETDEWEB)

Poly(ethylene terephthalate ) (PET) fibers were modified by deep UV irradiation which was produced by a low pressure mercury lamp. FT-IR and XPS analyses were used to elucidate the surface chemical composition of PET fibers treated with UV. Relative O{sub 1s} intensity increased considerably and it was found that oxygen was incorporated in the form of COO on the fiber surface. FT-IR and XPS analyses proved the existence of carboxylic groups on the surfaces and the adsorption test of cationic compound further supported these results. The concentration of carboxylic acid group on the surface increased remarkably with increasing irradiation time. XPS analysis and adsorption experiments proved that the surface structure of the UV{sub i}rradiated PET fibers were stable for 12 months. Antibacterial property and the deodorization rate of UV-irradiated PET fibers adsorbed with the berberine compound were investigated. reduction rates of bacteria increased by about 21 to 99% compared to unradiated PET fiber. Deodorization rates of 23% for unradiated PET fiber increased to about 75% for 30 min irradiated samples. (author). 33 refs., 3 tabs., 11 figs.

Kim, I.H.; Kim, S.H. [Sungkyunkwan University, Suwon (Korea)

2002-05-01

188

Synthesis of chlorogenic acid and p-coumaroyl shikimates from glucose using engineered Escherichia coli.  

Science.gov (United States)

Chlorogenic acid and hydroxylcinnamoyl shikimates are major dietary phenolics as well as antioxidants, with recently discovered biological, activities including protection against chemotheraphy side effects and prevention of cardiovascular disease and cancer. Certain fruits and vegetables produce these compounds, although a microbial system can also be utilized for synthesis of chlorogenic acid and hydroxylcinnamoyl shikimates. In this study, we engineered Escherichia coli to produce chlorogenic acid and p-coumaroyl shikimates from glucose. For the synthesis of chlorogenic acid, two E. coli strains were used; one strain for the synthesis of caffeic acid from glucose and the other strain for the synthesis of chlorogenic acid from caffeic acid and quinic acid. The final yield of chlorogenic acid using this approach was approximately 78 mg/l. To synthesize p-coumaroyl shikimates, wild-type E. coli as well as several mutants were tested. Mutant E. coli carrying deletions in three genes (tyrR, pheA, and aroL) produced 236 mg/l of p-coumaroyl shikimates. PMID:24786529

Cha, Mi Na; Kim, Hyeon Jeong; Kim, Bong Gyu; Ahn, Joong-Hoon

2014-08-28

189

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

Directory of Open Access Journals (Sweden)

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

190

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

191

Control of membrane polar lipid composition in Acholeplasma laidlawii a by the extent of saturated fatty acid synthesis.  

Science.gov (United States)

The low level of endogenous fatty acid synthesis in Acholeplasma laidlawii A strain EF22 was found to be caused by a deficiency of pantetheine in the lipid-depleted growth medium. By supplementing the oleic acid-containing medium with increasing concentrations of pantethein, saturated fatty acid synthesis was stimulated (having an apparent Km of 5 microM for pantetheine) and the incorporation of endogenously synthesized fatty acids in membrane lipids increased markedly. Furthermore, carotenoid biosynthesis was stimulated. Exogenous palmitic acid was found to inhibit partially the endogenous fatty acid synthesis. A gradual stimulation of fatty acid synthesis was accompanied by a linear increase in the molar proportion between the two dominating membrane glucolipids, monoglucosyldiacylglycerol and diglucosyldiacylglycerol. The total amount of charged membrane lipids decreased upon increasing the degree of fatty acid saturation. These regulations are discussed in terms of membrane stability, and influence of membrane molecular ordering and surface charge density on lipid polar head group synthesis. PMID:7352994

Christiansson, A; Wieslander, A

1980-01-25

192

The effect of nalidixic acid, rifampicin and chloramphenicol on the synthesis of phospholipase C in Bacillus cereus  

International Nuclear Information System (INIS)

The effect of nalidixic acid, rifampicin and chloramphenicol on the synthesis of phospholipase C (EC 3.1.4.3) has been studied in washed Bacillus cereus cells resuspended in nutrient broth. In the absence of inhibitors, the synthesis showed a biphasic pattern. No synthesis or release of enzyme was found in the presence of chloramphenicol. When rifampicin was added, phospholipase C synthesis for 10-15 min. Nalidixic acid, at concentrations which inhibited DNA synthesis completely, permitted the synthesis of phospholipase C at the same rate and for a similar length of time as rifampicin. (author)

193

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

194

Concise synthesis of Valerena-4,7(11)-diene, a highly active sedative, from valerenic acid.  

Science.gov (United States)

A concise synthesis of valerena-4,7(11)-diene with potent sedative activity was achieved in three steps involving, reduction of carboxylic acid, bromination of the resulting alcohol, and reduction of the bromide from valerenic acid in a 63% total yield. This synthetic method makes it possible to provide further materials for biological testing to realize comprehensive SAR studies. PMID:20834146

Kitayama, Takashi; Kawabata, Genki; Ito, Michiho

2010-01-01

195

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

Directory of Open Access Journals (Sweden)

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

196

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

197

Zinc mediated allylations of chlorosilanes promoted by ultrasound: synthesis of novel constrained sila amino acids.  

Science.gov (United States)

A simple, fast and efficient method for allylation and propargylation of chlorosilanes through zinc mediation and ultrasound promotion is reported. As a direct application of the resulting bis-allylsilanes, three novel, constrained sila amino acids are prepared for the first time. The design and synthesis of the constrained sila analogue of GABA (?-amino butyric acid) is a highlight of this work. PMID:24827151

Ramesh, Remya; Reddy, D Srinivasa

2014-06-28

198

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)

199

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 SciELO Brazil | Language: Portuguese Abstract in portuguese 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.

200

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

International Nuclear Information System (INIS)

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% 2H0 in the piperidine ring in any of the preparations. (author)

 
 
 
 
201

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

202

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

203

The effect of a poly(ethylene terephthalate) process residue on the rheological properties of coal tar pitch  

Energy Technology Data Exchange (ETDEWEB)

To modify a coal tar pitch, a PET-plant glycol-regeneration (waste) residue (GRR), i.e., a mixture of esters and oligoesters of terephthalic acid and mono and diethylene glycols was blended (GRR 0-30%). In addition to pitch structure changes, the modification involved substitution of H atoms in benzopyrene via C- and O-alkylations (by unsaturated polyester resin and poly(oxyethylene)diols, respectively). Flow curves softening point and penetration were measured for the blends.

Ciesinska, W. [Warsaw University of Science & Technology, Plock (Poland)

2002-10-01

204

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

205

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

206

Selective inhibition of leukotriene C/sub 4/ synthesis in human neutrophils by ethacrynic acid  

Energy Technology Data Exchange (ETDEWEB)

Addition of glutathione S-transferase inhibitors, ethyacrynic acid (ET), caffeic acid (CA), and ferulic acid (FA) to human neutrophils led to inhibition of leukotriene C/sub 4/ (LTC/sub 4/) synthesis induced by calcium ionophore A23187. ET is the most specific of these inhibitors for it had little effect on LTB/sub 4/, PGE/sub 2/, and 5-HETE synthesis. The inhibition of LTC/sub 4/ was irreversible and time dependent. ET also had little effect on /sup 3/H-AA release from A23187-stimulated neutrophils.

Leung, K.H.

1986-05-29

207

Effect of ursodeoxycholate and its taurine conjugate on bile acid synthesis and cholesterol absorption.  

Science.gov (United States)

Six male subjects with normal gastroenterologic function were studied to determine the effects of ursodeoxycholic (15 mg/kg X day) and tauroursodeoxycholic (20 mg/kg X day) acid feeding on bile acid synthesis and cholesterol absorption. Each bile acid was fed for 1 mo and withheld for the next month. Subjects remained on a metabolic ward and consumed a constant diet of 500 mg of cholesterol mixed with solid and liquid formulas. Before the study started, each subject received 50 muCi of [4-14C]cholesterol intravenously. During the study, stools were collected for the determination of 24-h fecal acidic and neutral sterol excretion, and blood was drawn twice weekly for determination of serum cholesterol specific activity. At the end of each month an intestinal perfusion study was performed to measure total bile acid pool size and hourly biliary secretion rates of cholesterol, phospholipid, and bile acid. From these data, the percentage of cholesterol absorption and total endogenous bile acid synthesis could be calculated. Neither ursodeoxycholic nor tauroursodeoxycholic acid feeding decreased endogenous bile acid synthesis. During bile acid feeding periods, the percentage of cholesterol absorption was decreased. PMID:6724255

Hardison, W G; Grundy, S M

1984-07-01

208

Theoretical investigations on the synthesis mechanism of cyanuric acid from NH? and CO?.  

Science.gov (United States)

In the synthesis of cyanuric acid from NH3 and CO2, urea and isocyanic acid OCNH are two pivotal intermediates. Based on density functional theory (DFT) calculations, the synthesis mechanism of cyanuric acid from NH3 + CO2 was investigated systematically. Urea can be synthesized from NH3 and CO2, and cyanuric acid can be obtained from urea or NH3 + CO2. In the stepwise mechanism of cyanuric acid from urea or NH3 + CO2, the energy barriers are relatively high, and the condition of high pressure and temperature does not decrease the energy barriers. Our theoretical model shows that cyanuric acid is actually acquired from OCNH via a one-step cycloaddition reaction. PMID:24077837

Cheng, Xueli; Zhao, Yanyun; Zhu, Weiqun; Liu, Yongjun

2013-11-01

209

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

210

75 FR 6634 - Polyethylene Terephthalate Film, Sheet, and Strip from India: Final Results of Countervailing...  

Science.gov (United States)

...Terephthalate Film, Sheet, and Strip from India: Final Results of Countervailing Duty...film, sheet, and strip (PET film) from India for the period January 1, 2007 through...Terephthalate Film, Sheet, and Strip from India: Preliminary Results of...

2010-02-10

211

76 FR 76365 - Polyethylene Terephthalate Film, Sheet, and Strip From the United Arab Emirates: Preliminary...  

Science.gov (United States)

...Polyethylene Terephthalate Film, Sheet, and Strip From the...on polyethylene terephthalate film, sheet, and strip (PET Film...previous review, and other PET Film cases. If JBF can demonstrate...which was not listed in the original questionnaire. JBF...

2011-12-07

212

Acetaldehyde residue in polyethylene terephthalate (PET) bottles.  

Science.gov (United States)

A simple sample preparation technique was developed for rapid analysis of acetaldehyde residue in Polyethylene Terephthalate (PET) bottles. A laboratory-built heating system was used and coupled with gas chromatography-flame ionization detector (GC-FID) at optimized conditions. The results were a tremendous reduction of the sample preparation time from 24 hours, for the conventional method, to only one hour. The analysis took only 1.5 min with other good analytical performances i.e. a low detection limit, 0.3 ng mL(- 1) and a wide linear dynamic range, 0.3 ng mL(- 1) to 6.6 microg mL(- 1) with R(2) > 0.99. Acetaldehyde residue in freshly blown bottles were analyzed and found in the range of 0.4 to 1.1 ng mL(- 1). The results were good agreement with the conventional 24-hour airspace method (P < 0.01). The PET-bottle sampling technique was also developed to minimize the complication of sample transportation and pre-concentration. A purge and trap technique was found to be the most suitable. Then, it was implemented and compared, the results showed no significant difference (P < 0.01) with and without purge and trap. PMID:17562466

Choodum, Aree; Thavarungkul, Panote; Kanatharana, Proespichaya

2007-01-01

213

Duodenal prostaglandin synthesis and acid load in health and in duodenal ulcer disease  

International Nuclear Information System (INIS)

We sought to test the hypothesis that duodenal ulcer disease results from an imbalance between duodenal acid load, an injurious force, and mucosal prostaglandin generation, a protective factor. Ten patients with duodenal ulcer and 8 healthy controls were studied. The duodenal acid load after an amino acid soup was quantified by a double-marker technique. Mucosal biopsy specimens were taken endoscopically from the duodenal bulb before and after the test meal. Prostaglandin synthesis activity was measured by incubating biopsy homogenates in excess [14C]arachidonic acid. Although mean duodenal acid load was higher in duodenal ulcer, ranges overlapped. Neither the qualitative nor quantitative profile of mucosal prostaglandin synthesis activities differed significantly between test groups. Prostaglandin synthesis activities, however, tended to increase post cibum in controls, but change little or decrease in duodenal ulcer. Only by comparing the responses with a meal of both parameters together (duodenal acid load and the change in prostaglandin synthesis activities) was there complete or nearly complete separation of duodenal ulcer from controls. Greatest discrimination was observed with prostacyclin (6-keto-PGF1 alpha). We conclude that in health, mucosal prostaglandin generation in the duodenum is induced post cibum in relation to duodenal acid load; this may be a physiologic example of adaptive cytoprotection. In duodenal ulcer there may be a defect in such a mechanism

214

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

215

Carbohydrates as chiral templates : stereoselective synthesis of (R)- and (S)-?-aminophosphonic acid derivatives  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The stereoselective synthesis of diethyl (S)- or (R)-?-[(O-pivaloyl-hexapyranosyl) amino]benzylphosphonates is achieved via Lewis acid catalyzed addition of diethyl phosphite to O-pivaloylated N-benzylidene -?-D-galactosylamine or N-benzylidene-?-D-arabinopyranosylamine. The process can also be performed by a one-pot procedure selectively giving (S)-aminophosphonic acid derivatives from galactosylamine and (R)-aminophosphonic acid derivatives from ?-L-fucosylamine as the c...

Laschat, Sabine; Kunz, Horst

1992-01-01

216

Phenolic acids in the wild mushroom Ganoderma lucidum and synthesis of some possible metabolites.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ganoderma lucidum is one of the most extensive!) studied mushrooms due to its medicinal properties, p-Hydroxybenzoic acid was the most abundant phenolic acid found in this mushroom. after HPLC-DAD-MS analysis. In the present work we describe the synthesis of glucuronide and methyl derivatives of p-hydroxybenzoic acid, which arc two of the main circulating metabolites found in humans. Their biological activity is going to be evaluated and compared to the parent compound in order...

Heleno, Sandrina A.; Ferreira, Isabel C. F. R.; Martins, Anabela; Esteves, Ana P.; Queiroz, Maria Joa?o R. P.

2012-01-01

217

Direct microwave-assisted amino acid synthesis by reaction of succinic acid and ammonia in the presence of magnetite  

Science.gov (United States)

Since the discovery of submarine hot vents in the late 1970s, it has been postulated that submarine hydrothermal environments would be suitable for emergence of life on Earth. To simulate warm spring conditions, we designed a series of microwave-assisted amino acid synthesis involving direct reactions between succinic acid and ammonia in the presence of the magnetite catalyst. These reactions which generated aspartic acid and glycine were carried out under mild temperatures and pressures (90-180 °C, 4-19 bar). We studied this specific reaction inasmuch as succinic acid and ammonia were traditionally identified as prebiotic compounds in primitive deep-sea hydrothermal systems on Earth. The experimental results were discussed in both biochemical and geochemical context to offer a possible route for abiotic amino acid synthesis. With extremely diluted starting materials (0.002 M carboxylic acid and 0.002 M ammonia) and catalyst loading, an obvious temperature dependency was observed in both cases [neither product was detected at 90 °C in comparison with 21.08 ?mol L-1 (aspartic acid) and 70.25 umol L-1 (glycine) in 180 °C]. However, an opposite trend presented for reaction time factor, namely a positive correlation for glycine, but a negative one for aspartic acid.

Jiang, Nan; Liu, Dandan; Shi, Weiguang; Hua, Yingjie; Wang, Chongtai; Liu, Xiaoyang

2013-10-01

218

Photocatalytic decarboxylative reduction of carboxylic acids and its application in asymmetric synthesis.  

Science.gov (United States)

The decarboxylative reduction of naturally abundant carboxylic acids such as ?-amino acids and ?-hydroxy acids has been achieved via visible-light photoredox catalysis. By using an organocatalytic photoredox system, this method offers a mild and rapid entry to a variety of high-value compounds including medicinally relevant scaffolds. Regioselective decarboxylation is achieved when differently substituted dicarboxylic acids are employed. The application of this method to the synthesis of enantioenriched 1-aryl-2,2,2-trifluoroethyl chiral amines starting from natural ?-amino acids further testifies to the utility of the developed photocatalytic decarboxylative reduction protocol. PMID:25068198

Cassani, Carlo; Bergonzini, Giulia; Wallentin, Carl-Johan

2014-08-15

219

Synthesis and structural analysis of 13C-fatty acids  

International Nuclear Information System (INIS)

The 13C-labelled fatty acids octanoic-1-13C acid and palmitic-1-13C acid were synthetically prepared from Ba 13CO3. The yield of the former was more than 90% and that of the latter was above 85%. MS, IR, 1H-NMR and 13NMR were performed to analyze the structures of the two 13C-fatty acids, compared with their unlabelled fatty acids

220

77 FR 9892 - Polyethylene Terephthalate Film, Sheet and Strip from India: Preliminary Intent to Rescind...  

Science.gov (United States)

...Terephthalate Film, Sheet and Strip From India: Rescission, In Part, of Countervailing...Terephthalate Film, Sheet and Strip From India: Rescission, In Part, of Countervailing...Terephthalate Film, Sheet and Strip from India'' (dated concurrently with this notice...d)(3), and consistent with our practice,\\3\\ we preliminarily determine...

2012-02-21

 
 
 
 
221

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

2013-01-01

222

Essential amino acid and carbohydrate ingestion before resistance exercise does not enhance postexercise muscle protein synthesis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ingestion of an essential amino acid-carbohydrate (EAA + CHO) solution following resistance exercise enhances muscle protein synthesis during postexercise recovery. It is unclear whether EAA + CHO ingestion before resistance exercise can improve direct measures of postexercise muscle protein synthesis (fractional synthetic rate; FSR). We hypothesized that EAA + CHO ingestion before a bout of resistance exercise would prevent the exercise-induced decrease in muscle FSR and would result in an e...

Fujita, Satoshi; Dreyer, Hans C.; Drummond, Micah J.; Glynn, Erin L.; Volpi, Elena; Rasmussen, Blake B.

2009-01-01

223

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

224

Inhibitors of Fatty Acid Synthesis Induce PPAR ? -Regulated Fatty Acid ? -Oxidative Genes: Synergistic Roles of L-FABP and Glucose.  

Science.gov (United States)

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 while binding C75 and C75-CoA with lower affinity. Binding of TOFA and C75-CoA significantly altered L-FABP secondary structure. High (20?mM) but not physiological (6?mM) glucose conferred on both TOFA and C75 the ability to induce PPAR ? transcription of the fatty acid ? -oxidative enzymes CPT1A, CPT2, and ACOX1 in cultured primary hepatocytes from wild-type (WT) mice. However, L-FABP gene ablation abolished the effects of TOFA and C75 in the context of high glucose. These effects were not associated with an increased cellular level of unesterified fatty acids but rather by increased intracellular glucose. These findings suggested that L-FABP may function as an intracellular fatty acid synthesis inhibitor binding protein facilitating TOFA and C75-mediated induction of PPAR ? in the context of high glucose at levels similar to those in uncontrolled diabetes. PMID:23533380

Huang, Huan; McIntosh, Avery L; Martin, Gregory G; Petrescu, Anca D; Landrock, Kerstin K; Landrock, Danilo; Kier, Ann B; Schroeder, Friedhelm

2013-01-01

225

Continuous-flow solid-phase Peptide synthesis: a revolutionary reduction of the amino Acid excess.  

Science.gov (United States)

A highly efficient continuous-flow technique for the synthesis of peptides was developed. The method allows the application of only 1.5 equivalents of amino acids during coupling, while yielding virtually quantitative conversions. A mesoscale reactor was constructed which permits the use of high temperature and pressure during the synthesis. A complete reaction parameter optimization was carried out. Under the optimum conditions, the couplings of all 20 proteinogenic amino acids were achieved with 1.5 amino acid equivalents with quantitative conversions. As a demonstration of the efficiency of the methodology, difficult sequences and ?-peptide foldamers with alicyclic side-chains were synthetized in excellent yields and with lower costs thanks to the lower amounts of amino acid and solvent used. By this the synthesis is highly economic and sustainable. Importantly, exotic and expensive artificial amino acids were incorporated into peptidic sequences by the utilization of a reasonable number of amino acid equivalents. The synthesis can be performed in quantities of microgram to gram in an automated way. PMID:25196512

Mándity, István M; Olasz, Balázs; Otvös, Sándor B; Fülöp, Ferenc

2014-11-01

226

Receptor-mediated uptake of low density lipoprotein stimulates bile acid synthesis by cultured rat hepatocytes  

International Nuclear Information System (INIS)

The cellular mechanisms responsible for the lipoprotein-mediated stimulation of bile acid synthesis in cultured rat hepatocytes were investigated. Adding 280 micrograms/ml of cholesterol in the form of human or rat low density lipoprotein (LDL) to the culture medium increased bile acid synthesis by 1.8- and 1.6-fold, respectively. As a result of the uptake of LDL, the synthesis of [14C]cholesterol from [2-14C]acetate was decreased and cellular cholesteryl ester mass was increased. Further studies demonstrated that rat apoE-free LDL and apoE-rich high density lipoprotein (HDL) both stimulated bile acid synthesis 1.5-fold, as well as inhibited the formation of [14C]cholesterol from [2-14C]acetate. Reductive methylation of LDL blocked the inhibition of cholesterol synthesis, as well as the stimulation of bile acid synthesis, suggesting that these processes require receptor-mediated uptake. To identify the receptors responsible, competitive binding studies using 125I-labeled apoE-free LDL and 125I-labeled apoE-rich HDL were performed. Both apoE-free LDL and apoE-rich HDL displayed an equal ability to compete for binding of the other, suggesting that a receptor or a group of receptors that recognizes both apolipoproteins is involved. Additional studies show that hepatocytes from cholestyramine-treated rats displayed 2.2- and 3.4-fold increases in the binding of apoE-free LDL and apoE-rich HDL, respectively. These data show for the first time that receptor-mediated uptake of LDL by the liver is intimately linked to processes activating bile acid synthesis

227

Peptide nucleic acids: structure, properties, applications, strategies and practice of chemical synthesis  

International Nuclear Information System (INIS)

The information on the structure and properties of peptide nucleic acids (PNA) is generalised. The use of PNA oligomers in biomolecular studies and biotechnology is exemplified. The published data on the most important methods for the chemical synthesis of PNA oligomers with the main emphasis on the efficiency of condensation reactions are considered. The methods for PNA synthesis are systematised; their advantages and disadvantages are discussed. Some recommendations for optimisation of the condensation procedure and synthesis of PNA are presented. The bibliography includes 153 references.

228

Synthesis and structural characterization of a new open-framework zinc terephthalate Zn3(OH)2(bdc)2.2DEF, with infinite Zn-(?3-OH)-Zn chains  

International Nuclear Information System (INIS)

A new zinc carboxylate Zn3(OH)2(bdc)2.2DEF was synthesized under mild hydrothermal conditions (100oC, 40h) in the presence of 1,4-benzenedicarboxylic (bdc) acid, in N,N'-diethylformamide (DEF) solvent. Its structure, characterized by means of single-crystal XRD analysis, consists of connection of ZnO2(OH)2 tetrahedra corner-sharing with ZnO4(OH)2 octahedra. Two adjacent ZnO2(OH)2 tetrahedra have a common edge corresponding to hydroxy group, which is also linked to the octahedrally coordinated zinc atoms with a ?3 configuration. This resulting connection mode generates infinite chains running along the c-axis, and connected to each other via the bdc ligand. Three-dimensional framework is therefore formed with channels running along the c-axis, parallel to the infinite Zn-OH-Zn chains. Within the tunnels are trapped the DEF species, which interacts via hydrogen-bond to the ?3-hydroxy of the zinc chains with the terminal oxygen atom of the formamide function. Analysis by solid state NMR (1H and 13C) has confirmed both the presence of occluded solvent molecules within the pores and the incorporation of carboxylate moieties into the framework. The structure of Zn3(OH)2(bdc)2.2DEF is closely related to those of MOF-69 series, constructed with longer organic linkers (4,4'-biphenyldicarboxylate and 2,6-naphthalenedicarboxylate). The structure is observed to loose crystallinity upon heating and removal of the occluded DEF moieties. Crystal data for [Zn9(OH)6(O2C-C6H4-CO2)6].6[(CH3-CH2)2NCHO]: a=17.7374(3)A, b=15.2605(2)A, c=18.2635(2)A, ?=113.071(1)o, V=4548.2(1)A3, P21/n (no. 14), Z=1, R1=0.0510, wR2=0.1302 for 11877 reflections I>2?(I)

229

Aqueous Microwave-Assisted Solid-Phase Synthesis Using Boc-Amino Acid Nanoparticles  

Directory of Open Access Journals (Sweden)

Full Text Available We have previously developed water-based microwave (MW-assisted peptide synthesis using Fmoc-amino acid nanopaticles. It is an organic solvent-free, environmentally friendly method for peptide synthesis. Here we describe water-based MW-assisted solid-phase synthesis using Boc-amino acid nanoparticles. The microwave irradiation allowed rapid solid-phase reaction of nanoparticle reactants on the resin in water. We also demonstrated the syntheses of Leu-enkephalin, Tyr-Gly-Gly-Phe-Leu-OH, and difficult sequence model peptide, Val-Ala-Val-Ala-Gly-OH, using our water-based MW-assisted protocol with Boc-amino acid nanoparticles.

Yoshinobu Fukumori

2013-07-01

230

Synthesis of [18-14C]octatriacontane from [1-14C]stearic acid  

International Nuclear Information System (INIS)

A method was developed to synthesize 14C-labelled n-alkanes for use in cigarette smoke studies. Specifically, n-[18-14C]-octatriacontane was synthesized from 1 mCi [1-14C]stearic acid in a radiochemical yield of 20%. The key features of this synthesis were two consecutive alkylations of tosylmethyl isocyanide followed by acid hydrolysis to [18-14C]-19-octatriacontanone and modified Wolff-Kishner reduction to the n-alkane. After purification on silica gel 25 mg of [18-14C]octatriacontane was obtained with a total radioactivity of 200 ?Ci, a specific activity of 4.3 mCi/mmol, and a radiochemical purity in excess of 98% by thin layer radiochromatography. The method has also been applied to the synthesis of unlabeled n-pentatriacontane and is considered to be generally applicable to the synthesis of radiolabeled alkanes from radiolabeled fatty acids. (author)

231

Safety assessment of modified terephthalate polymers as used in cosmetics.  

Science.gov (United States)

The safety of 6 modified terephthalate polymers as cosmetic ingredients was assessed. These ingredients mostly function as exfoliants, bulking agents, hair fixatives, and viscosity-increasing agents-nonaqueous. Polyethylene terephthalate (PET) is used in leave-on products up to 100% and in rinse-off products up to 2%. The Cosmetic Ingredient Review Expert Panel (Panel) considered that the PET used in cosmetics is chemically equivalent to that used in medical devices. The Panel determined that the Food and Drug Administration's determination of safety of PET in several medical devices, which included human and animal safety data, can be used as the basis for the determination of safety of PET and related polymers used in cosmetics. Use studies of cosmetic eye products that contain PET demonstrated no ocular irritation or dermal sensitization. The Panel concluded that modified terephthalate polymers were safe as cosmetic ingredients in the practices of use and concentration described in this safety assessment. PMID:25297907

Becker, Lillian C; Bergfeld, Wilma F; Belsito, Donald V; Hill, Ronald A; Klaassen, Curtis D; Liebler, Daniel C; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

2014-09-01

232

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish 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

233

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish 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.

234

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

235

Palladium-Catalyzed Multicomponent Synthesis of 2-Imidazolines from Imines and Acid Chlorides  

Directory of Open Access Journals (Sweden)

Full Text Available We describe the palladium-catalyzed multicomponent synthesis of 2-imidazolines. This reaction proceeds via the coupling of imines, acid chlorides and carbon monoxide to form imidazolinium carboxylates, followed by a decarboxylation. Decarboxylation in CHCl3 is found to result in a mixture of imidazolinium and imidazolium salts. However, the addition of benzoic acid suppresses aromatization, and generates the trans-disubstituted imidazolines in good yield. Combining this reaction with subsequent nitrogen deprotection provides an overall synthesis of imidazolines from multiple available building blocks.

Boran Xu

2012-11-01

236

On the synthesis of 11C-labelled aromatic amino acids  

International Nuclear Information System (INIS)

belled 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)

237

THE EFFECT OF A NEW SALICYLIC ACID SYNTHESIS COMPOUNDS ADMINISTRATION ON SERUM TRANSAMINASIS  

Directory of Open Access Journals (Sweden)

Full Text Available The chemical synthesis product is the amide of chlorine salicylic acid andsulphanilamide (5ClSA-SA. This research had as objective the effect of this productfrom salicylic acid class as a potential medicine on the serum transaminasis activity.5ClSA-SA has been administrated intraperitoneal to Wistar rats for 7 daysconsecutively determining ALT and AST transaminasis activities after 5 and 7 days.Serum transaminases had high values compared to the control sample (220% ASTand 237% ALT.This synthesis product can lead to stress that induces increasing of plasmaticenzymes activity, transaminasis being one of those.

STANA LETI?IA

2007-01-01

238

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

239

A captive solvent method for rapid radiosynthesis: application to the synthesis of 1-11C palmitic acid  

International Nuclear Information System (INIS)

A method is described for the synthesis of [1-11C]palmitic acid, in which 11CO2 is reacted with a Grignard reagent trapped within the pores of microporous polypropylene powder in a column. The free acid is liberated by passing gaseous HCl through the column. The apparatus is very simple, facilitating automation and miniaturization of the synthesis. (author)

240

Chemical Synthesis Pharmaceutical Wastewater Containing Sulfadiazine (SD and Ketoprofen(KP Treatment by Acid Separating  

Directory of Open Access Journals (Sweden)

Full Text Available Containing sulfadiazine (SD and ketoprofen (KP on the synthesis of pharmaceutical wastewater has a stronger effect on treatment of microbes. It is not used to be dealt with by wastewater treatment. This study shows that acid separation can improve bio-chemistry catabolism of the synthesis of pharmaceutical wastewater clearly. The acid separation to increase the biodegradability of waste water is conducive to aerobic and anaerobic bacteria domesticated, screened and compound treatment. Aerobic and anaerobic wastewater treatment can be done well after acid separated. Analysis of experimentation has proved that COD (chemical oxygen demand of original wastewater falls below 150 mg·L-1 from 2 52 5 mg·L-1, at last reaches to 145 mg·L-1 finally. The total removal rate of COD is about 94%. According to test it can be gotten that acid separation of the best conditions is :pH=2, acid sparating process time is 40 minut. Tests show that pretreatment of acid separation to high concentration of chemical synthesis is the key to pharmaceutical wastewater which is done by aerobic and anaerobic bacteria after acid separation.

CHEN Xi

2009-06-01

 
 
 
 
241

Synthesis of glycosyl-amino acids of biological interest; Sintese de glicoaminoacidos de interesse biologico  

Energy Technology Data Exchange (ETDEWEB)

This work describes the synthesis of the glycosylated amino acids {alpha}GlcNAc-Thr, {beta}GlcNAc-Thr and {alpha}LacNAc-Thr by the glycosylation reaction of the amino acid threonine with the corresponding glycosyl donors {alpha}GlcNAcCl and {alpha}LacN3Cl. The glycosylated amino acids containing the sugar units {alpha}-D-GlcNAc and {alpha}-D-LacNAc O-linked to threonine amino acids are related to O-glycans found in mucins of the parasite Trypanosoma cruzi, while the corresponding {beta}-D-GlcNAc isomer is involved in cellular signaling events. (author)

Campo, Vanessa Leiria; Carvalho, Ivone [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Ciencias Farmaceuticas]. E-mail: carronal@usp.br

2008-07-01

242

Enantiopure synthesis of side chain-modified ?-amino acids and 5-cis-alkylprolines.  

Science.gov (United States)

A short, concise synthesis of enantiopure, side chain-modified ?-amino acids such as 4-oxo-L-norvaline, 6-oxo-L-homonorleucine, and 5-cis-alkyl prolines is described. Knoevenagel condensation of l-aminocarboxylate-derived ?-ketoesters with aldehydes followed by reductive decarboxylation results in unnatural ?-amino acids in good yield. A fluorescent amino acid is synthesized using a similar protocol. These studies show that aminocarboxylate-derived ?-ketoesters are very useful intermediates and the method employed is both general and practical for the preparation of ?(?)-oxo ?-amino acids and alkylprolines. PMID:22616793

Mohite, Amar R; Bhat, Ramakrishna G

2012-06-15

243

Racemic synthesis and solid phase peptide synthesis application of the chimeric valine/leucine derivative 2-amino-3,3,4-trimethyl-pentanoic acid.  

Science.gov (United States)

The synthesis of non natural amino acid 2-amino-3,3,4-trimethyl-pentanoic acid (Ipv) ready for solid phase peptide synthesis has been developed. Copper (I) chloride Michael addition, followed by a Curtius rearrangement are the key steps for the lpv synthesis. The racemic valine/leucine chimeric amino acid was then successfully inserted in position 5 of neuropeptide S (NPS) and the diastereomeric mixture separated by reverse phase HPLC. The two diastereomeric NPS derivatives were tested for intracellular calcium mobilization using HEK293 cells stably expressing the mouse NPS receptor where they behaved as partial agonist and pure antagonist. PMID:25073393

Pelà, M; Del Zoppo, L; Allegri, L; Marzola, E; Ruzza, C; Calo, G; Perissutti, E; Frecentese, F; Salvadori, S; Guerrini, R

2014-07-01

244

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

Energy Technology Data Exchange (ETDEWEB)

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 /sup 3/H/sub 2/O, enzyme activities were measured spectrophotometrically except for AC which was assayed with /sup 14/C-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.

Nelson, G.; Kelley, D.; Schmidt, P.; Virk, S.; Serrato, C.

1986-05-01

245

The Use of Ascorbate as an Oxidation Inhibitor in Prebiotic Amino Acid Synthesis: A Cautionary Note  

Science.gov (United States)

It is generally thought that the terrestrial atmosphere at the time of the origin of life was CO2-rich and that organic compounds such as amino acids would not have been efficiently formed abiotically under such conditions. It has been pointed out, however, that the previously reported low yields of amino acids may have been partially due to oxidation by nitrite/nitrate during acid hydrolysis. Specifically, the yield of amino acids was found to have increased significantly (by a factor of several hundred) after acid hydrolysis with ascorbic acid as an oxidation inhibitor. However, it has not been shown that CO2 was the carbon source for the formation of the amino acids detected after acid hydrolysis with ascorbic acid. We therefore reinvestigated the prebiotic synthesis of amino acids in a CO2-rich atmosphere using an isotope labeling experiment. Herein, we report that ascorbic acid does not behave as an appropriate oxidation inhibitor, because it contributes amino acid contaminants as a consequence of its reactions with the nitrogen containing species and formic acid produced during the spark discharge experiment. Thus, amino acids are not efficiently formed from a CO2-rich atmosphere under the conditions studied.

Kuwahara, Hideharu; Eto, Midori; Kawamoto, Yukinori; Kurihara, Hironari; Kaneko, Takeo; Obayashi, Yumiko; Kobayashi, Kensei

2012-12-01

246

Synthesis of (?-methyl 3H)-6?-iodopenicillanic acid  

International Nuclear Information System (INIS)

A rapid and easy synthesis of tritium-labelled ?-iodopenicillanate, an efficient inactivator of serine ?-lactamase, is described. This method involves only three reaction steps after the introduction of the label in the molecule with an overall yield of 16%. (author)

247

Synthesis of racemic, R- and S-[1-11C]-?-hydroxybutyric acid  

International Nuclear Information System (INIS)

Racemic, R- and S-?-hydroxybutyric acid were labelled with 11C in the carboxylic position by a two-step stereospecific synthesis starting with carrier-added [11C]cyanide and R/S, R- or S-propylene oxide. Hydrolysis of the intermediate nitrile with hydrochloric acid gave racemic [1-11C]-?-hydroxybutyric acid and R- or S-[1-11C]-?-hydroxybutyric acid with an enantiomeric excess of 87-97%. The total synthesis time (including HPLC purification) was 45-50 min from end of trapping. The isolated decay-corrected radiochemical yield was 20-30% based on [11C]cyanide. The radiochemical purity of the products was > 99%]. (author)

248

Fatty acid synthesis: a potential selective target for antineoplastic therapy.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

OA-519 is a prognostic molecule found in tumor cells from breast cancer patients with markedly worsened prognosis. We purified OA-519 from human breast carcinoma cells, obtained its peptide sequence, and unambiguously identified it as fatty acid synthase through sequence homology and enzymology. Tumor fatty acid synthase is an approximately 270-kDa polypeptide which specifically abolished immunostaining of human breast cancers by anti-OA-519 antibodies. Tumor fatty acid synthase oxidized NADP...

Kuhajda, F. P.; Jenner, K.; Wood, F. D.; Hennigar, R. A.; Jacobs, L. B.; Dick, J. D.; Pasternack, G. R.

1994-01-01

249

Acyl Meldrum's acid derivatives: application in organic synthesis  

Science.gov (United States)

This review is focused on an important class of Meldrum's acid derivatives commonly known as acyl Meldrum's acids. The preparation methods of these compounds are considered including the recently proposed and rather rarely used ones. The chemical properties of acyl Meldrum's acids are described in detail, including thermal stability and reactions with various nucleophiles. The possible mechanisms of these transformations are analyzed. The bibliography includes 134 references.

Janikowska, K.; Racho?, J.; Makowiec, S.

2014-07-01

250

Synthesis of the enantiomers of 3-deuterium labelled lactic acid  

International Nuclear Information System (INIS)

Both R- and S-enantiomers of 3-monodeuterated lactic acid ([3-2H]-2(R) and 2(S)-hydroxypropanoic acids) were synthesized by regiospecific nucleophilic opening of diastereoisomer epoxides derived from D-mannitol, with lithium aluminium deuteride. Spectroscopic analysis of the product shows a complete deutero-incorporation which makes [3-2H]-lactic acid suitable as an internal standard using gas chromatography-mass spectroscopy. (author)

251

Photochemical Synthesis of the Bioconjugate Folic Acid-Gold Nanoparticles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2013-01-01

252

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)

253

Ready protease-catalyzed synthesis of carbohydrate-amino acid conjugates.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The protease-catalyzed synthesis of amino acid est-carbohydrate conjugates as glycopeptide analogues has been achieved in a highly regioselective and carbohydrate-specific manner using amino acid vinyl ester acyl donors and minimally or completely unprotected carbohydrate acyl acceptors, which together probed active sites of proteases to reveal yield efficiencies that are modulated by the carbohydrate C-2 substitutent, and that may be exploited to allow selective one-pot syntheses.

Boyer, V.; Stanchev, M.; Fairbanks, Aj; Davis, Bg

2001-01-01

254

Synthesis and pharmacological evaluation of cyclodextrin conjugate prodrug of mefenamic acid  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the present investigation mefenamic acid prodrug of ?-cyclodextrins was synthesized. The primary hydroxy group of ?-cyclodextrins was used to block the acid group. The synthesis involved a series of protection and deprotection reaction. The ester was evaluated for stability in simulated gastric and intestinal fluid. The hydrolysis of cyclodextrin conjugate in colon is confirmed by the hydrolysis kinetics studies in rat faecal material. The ester was also evaluated for ulcerogenic...

Dev S; Mhaske Deepali; Kadam S; Dhaneshwar S

2007-01-01

255

Synthesis of novel acid -sensitive lipids and their application in drug and gene delivery  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthesis and drug and gene delivery applications of four acid-labile, vinyl ether containing lipids is described. Under low pH conditions, enhanced contents release was observed from dioleoylphosphatidyl ethanolamine (DOPE) liposomes stabilized with doping quantities of two novel acid-labile poly(ethylene glycol)-lipid conjugates, relative to a non-labile analog and release at neutral pH. Cleavage of the vinyl ether linkage removes the poly(ethylene glycol) corona from the surface, there...

Boomer, Jeremy Alan

2000-01-01

256

Expedient Synthesis of Chiral ?-Amino Acids through Nickel-Catalyzed Reductive Cross-Coupling.  

Science.gov (United States)

A novel method for the synthesis of non-natural L- and D-amino acids by a Ni-catalyzed reductive cross-coupling reaction is described. This strategy enables the racemization-free cross-coupling of serine/homoserine- derived iodides with aryl/acyl/alkyl halides. It provides convenient access to varieties of enantiopure and functionalized amino acids, which are important building blocks in bioactive compounds and pharmaceuticals. PMID:25314635

Lu, Xi; Yi, Jun; Zhang, Zhen-Qi; Dai, Jian-Jun; Liu, Jing-Hui; Xiao, Bin; Fu, Yao; Liu, Lei

2014-11-17

257

Enzymatic synthesis of 11C-pyruvic acid and 11C-L-lactic acid  

International Nuclear Information System (INIS)

L-Lactic acid is formed as the end product of glycolysis under anaerobic conditions in all cells, but this reaction is of special significance in the myocardium. L-Lactic acid is reversibly formed from and is in equilibrium with myocardial pyruvic acid, which is its sole metabolic pathway. 11C-Pyruvic acid is synthesized from 11C carbon dioxide using pyruvate-ferredoxin oxidoreductase and coenzymes. The 11C-pyruvic acid is then converted to 11-L-lactic acid by lactic acid dehydrogenase. The availability of 11C-pyruvic acid and 11C-L-lactic acid will permit the in vivo investigation of lactate metabolism. (author)

258

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

259

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)

260

Synthesis of homo and hetero metal-phosphonate frameworks from bi-functional aminomethylphosphonic acid  

International Nuclear Information System (INIS)

The reaction between aminomethylphosphonic acid (ampa) and the metal salts of Zn, Cd, Hg, Pb, Ag, and Cu afforded seven metal-phosphonate polymers with unique structural features and includes the synthesis of a bimetallic metal-organic framework (Cu/Ag). The characterization of these metal phosphonates is reported by means of infrared spectroscopy, 1H-NMR, 31P-NMR, X-ray crystallography, energy dispersive X-ray (EDX), and thermogravimetric analysis (TGA). Individual structural features are compared based on the preferred coordination mode of ampa and the geometrical requirements for each metallic center that manipulates the structural motif. - Graphical abstract: The synthesis and characterization of polymeric metal phosphonates featuring zinc, cadmium, mercury, lead, and silver phosphonate are described from the reactions of the bi-funtional aminomethylphosphonic acid with the metal precursor in aqueous conditions. These previously undescribed polymers display unusual structural features and include the synthesis of a bimetallic metal-organic framework (Cu/Ag)

 
 
 
 
261

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

262

Bridged Ring Systems. Xiii. The Synthesis of Cycloheptene Carboxylic Acids.  

Science.gov (United States)

Beta-(2-oxocyclopentyl) ethylaryl ketones are transformed under acid conditions via a 2-arylbicyclo (3.2.1)oct-2-en-8-one intermediate into a mixture of arylcycloheptene carboxylic acids. The scope and the mechanism of the reaction are both discussed. (Au...

G. L. Buchanan, A. C. W. Curran, J. M. McCrae, G. W. McLay

1968-01-01

263

EFFECTS OF ETHYLENE CHLOROHYDRIN ON FATTY ACID SYNTHESIS  

Science.gov (United States)

Male chicks weighing 700 to 900 g. received an acute or eight doses IG of 60 or 40 mg/kg ethylene chlorohydrin (ECH) respectively and were sacrificed eighteen hours after the last dose. Mitochondrial elongation of fatty acids was decreased significantly while fatty acid synthetas...

264

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...

265

Synthesis of medium-chain fatty acids and their incorporation into triacylglycerols by cell-free fractions from Cuphea embryos.  

Science.gov (United States)

During their rapid maturation period, seeds of Cuphea wrightii A. Gray mainly accumulate medium-chain fatty acids (C8 to C14) in their storage lipids. The rate of lipid deposition (40-50 mg·d(-1)·(g fresh weight)(-1)) is fourfold higher than in seeds of Cuphea racemosa (L. f.) Spreng, which accumulate long-chain fatty acids (C16 to C18). Measurements of the key enzymes of fatty-acid synthesis in cell-free extracts of seeds of different maturities from Cuphea wrightii show that malonyl-CoA synthesis may be a triggering factor for the observed high capacity for fatty-acid synthesis. Experiments on the incorporation of [1-(14)C]acetate into fatty acids by purified plastid preparations from embryos of Cuphea wrightii have demonstrated that the biosynthesis of medium-chain fatty acids (C8 to C14) is localized in the plastid. Thus, in the presence of cofactors for lipid synthesis (ATP, NADPH, NADH, acyl carrier protein, and sn-glycerol-3-phosphate), purified plastid fractions predominantly synthesized free fatty acids, 30% of which were of medium chain length. Transesterification of the freshly synthesized fatty acids to coenzyme A and recombination with the microsomal fraction of the embryo homogenate induced triacylglycerol synthesis. It also stimulated fatty-acid synthesis by a factor 2-3 and increased the relative amount of medium-chain fatty acids bound to triacylglycerols, which corresponded to about 60-80% in this lipid fraction. PMID:24202026

Deerberg, S; von Twickel, J; Förster, H H; Cole, T; Fuhrmann, J; Heise, K P

1990-02-01

266

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

267

Rapid and efficient synthesis of [1,2-14C] acetic acid  

International Nuclear Information System (INIS)

The method for the synthesis of mmol quantities of [1,2-14C] acetic acid with molar activity equal to or higher than 3.7 GBqxmmol-1 (100 mCixmmol-1) based on the step hydration and oxidation of [1,2-14C] ethine is described. The 85% radiochemical yield on starting Ba14CO3 was achieved. (author)

268

Silica sulfuric acid catalyzed one-pot synthesis of Biginelli reaction in water  

Directory of Open Access Journals (Sweden)

Full Text Available Silica Sulphuric Acid-catalyzed, simple, one-pot, cost effective and environmentally benign process for the synthesis of dihydropyrimidones is described. The novel compuounds were tested for antibacterial activity and was found to be effective against some gram positive and gram negative bacteria..

Mazahar Farooqui

2013-05-01

269

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...

270

Oxidative cross-coupling of allenyl ketones and organoboronic acids: expeditious synthesis of highly substituted furans.  

Science.gov (United States)

Allenyl ketones are employed as coupling partners in palladium-catalyzed oxidative cross-coupling reactions with organoboronic acids. This reaction constitutes an efficient methodology for the synthesis of highly substituted furan derivatives. Palladium-carbene migratory insertion is proposed as the key step in this transformation. PMID:24615951

Xia, Ying; Xia, Yamu; Ge, Rui; Liu, Zhen; Xiao, Qing; Zhang, Yan; Wang, Jianbo

2014-04-01

271

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)

272

Synthesis and biological evaluation of new salicylate macrolactones from anacardic acids  

Energy Technology Data Exchange (ETDEWEB)

onnection 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)

Logrado, Lucio P.L.; Santos, Maria Lucilia dos [Brasilia Univ., DF (Brazil). Inst. de Quimica. Lab. de Isolamento e Transformacao de Moleculas Organicas]. E-mail: mlsantos@unb.br; Silveira, Damaris [Brasilia Univ., DF (Brazil). Faculdade de Ciencias da Saude; Romeiro, Luiz A.S. [Universidade Catolica de Brasilia, Taguatinga, DF (Brazil). Nucleo de Quimica Bioorganica e Medicinal; Moraes, Manoel O. de; Cavalcanti, Bruno C.; Costa-Lotufo, Leticia V.; Pessoa, Claudia do O [Ceara Univ., Fortaleza, CE (Brazil). Lab. de Oncologia Experimental

2005-11-15

273

Essential role of ELOVL4 protein in very long chain fatty acid synthesis and retinal function.  

Science.gov (United States)

Very long chain polyunsaturated fatty acid (VLC-PUFA)-containing glycerophospholipids are highly enriched in the retina; however, details regarding the specific synthesis and function of these highly unusual retinal glycerophospholipids are lacking. Elongation of very long chain fatty acids-4 (ELOVL4) has been identified as a fatty acid elongase protein involved in the synthesis of VLC-PUFAs. Mutations in ELOVL4 have also been implicated in an autosomal dominant form of Stargardt disease (STGD3), a type of juvenile macular degeneration. We have generated photoreceptor-specific conditional knock-out mice and used high performance liquid chromatography-mass spectrometry (HPLC-MS) to examine and analyze the fatty acid composition of retinal membrane glycerophosphatidylcholine and glycerophosphatidylethanolamine species. We also used immunofluorescent staining and histology coupled with electrophysiological data to assess retinal morphology and visual response. The conditional knock-out mice showed a significant decrease in retinal glycerophospholipids containing VLC-PUFAs, specifically contained in the sn-1 position of glycerophosphatidylcholine, implicating the role of Elovl4 in their synthesis. Conditional knock-out mice were also found to have abnormal accumulation of lipid droplets and lipofuscin-like granules while demonstrating photoreceptor-specific abnormalities in visual response, indicating the critical role of Elovl4 for proper rod or cone photoreceptor function. Altogether, this study demonstrates the essential role of ELOVL4 in VLC-PUFA synthesis and retinal function. PMID:22199362

Harkewicz, Richard; Du, Hongjun; Tong, Zongzhong; Alkuraya, Hisham; Bedell, Matthew; Sun, Woong; Wang, Xiaolei; Hsu, Yuan-Hao; Esteve-Rudd, Julian; Hughes, Guy; Su, Zhiguang; Zhang, Ming; Lopes, Vanda S; Molday, Robert S; Williams, David S; Dennis, Edward A; Zhang, Kang

2012-03-30

274

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

275

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

Science.gov (United States)

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.

2001-11-01

276

(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

277

Function of Heterologous Mycobacterium tuberculosis InhA, a Type 2 Fatty Acid Synthase Enzyme Involved in Extending C20 Fatty Acids to C60-to-C90 Mycolic Acids, during De Novo Lipoic Acid Synthesis in Saccharomyces cerevisiae?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We describe the physiological function of heterologously expressed Mycobacterium tuberculosis InhA during de novo lipoic acid synthesis in yeast (Saccharomyces cerevisiae) mitochondria. InhA, representing 2-trans-enoyl-acyl carrier protein reductase and the target for the front-line antituberculous drug isoniazid, is involved in the activity of dissociative type 2 fatty acid synthase (FASII) that extends associative type 1 fatty acid synthase (FASI)-derived C20 fatty acids to form C60-to-C90 ...

Gurvitz, Aner; Hiltunen, J. Kalervo; Kastaniotis, Alexander J.

2008-01-01

278

Electronically coupled MM quadruply-bonded complexes (M = Mo or W) employing functionalized terephthalate bridges: toward molecular rheostats and switches.  

Science.gov (United States)

Toluene solutions of M2(O2C(t)Bu)4 (M = Mo, W; 2 equiv) react with a range of functionalized terephthalic acids, HO2CArCO2H (Ar = C6H4, C6F4, C6Cl4, C6H2-2,5-Cl2, C6H2-2,5-(OH)2, C6H3-2-F), to give [(tBuCO2)3M2]2[mu-O2CArCO2]. These compounds show intense ML(bridge)CT absorptions in the visible region of the electronic spectrum, and the terephthalate bridge serves to electronically couple the two M2 units via interactions between the M2 delta and bridge pi orbitals. Electronic structure calculations reveal how the degree of electronic coupling is controlled by the dihedral angles between the terephthalate C6 ring and the two CO2 units and the degree of interaction between the M4 delta MOs and the LUMO of the bridge. Both of these factors are controlled by the aryl substituents, and collectively these determine the thermochromism displayed by these complexes in solution together with the physical properties of the oxidized radical cations as determined by electrochemical studies (CV, DPV), UV-vis-NIR and EPR spectroscopic methods. PMID:16366568

Chisholm, Malcolm H; Feil, Florian; Hadad, Christopher M; Patmore, Nathan J

2005-12-28

279

Synthesis of quinoxalines in the presence of heteropoly acids  

Directory of Open Access Journals (Sweden)

Full Text Available Efficient synthesis of quinoxaline derivatives from the reaction of ?-diketones and o-phenylenediamines in the presence of Keggin-type heteropolyacids (HPA such as H3PMo12O40, H4SiW12O40, K7PMo2W9O40, H3PW12O40.SiO2 and H3PW12O40 in high yields and short reaction times, and at room temperature is introduced.

Fatemeh Hakimia

2013-04-01

280

Synthesis of acid-base bifunctional mesoporous materials by oxidation and thermolysis  

International Nuclear Information System (INIS)

Graphical abstract: A novel and efficient method has been developed for the synthesis of acid-base bifunctional catalyst. The obtained sample of SO3H-MCM-41-NH2 containing amine and sulfonic acids exhibits excellent catalytic activity in aldol condensation reaction. Research highlights: ? Synthesize acid-base bifunctional mesoporous materials SO3H-MCM-41-NH2. ? Oxidation and then thermolysis to generate acidic site and basic site. ? Exhibit good catalytic performance in aldol condensation reaction between acetone and various aldehydes. -- Abstract: A novel and efficient method has been developed for the synthesis of acid-base bifunctional catalyst SO3H-MCM-41-NH2. This method was achieved by co-condensation of tetraethylorthosilicate (TEOS), 3-mercaptopropyltrimethoxysilane (MPTMS) and (3-triethoxysilylpropyl) carbamicacid-1-methylcyclohexylester (3TAME) in the presence of cetyltrimethylammonium bromide (CTAB), followed by oxidation and then thermolysis to generate acidic site and basic site. X-ray diffraction (XRD) and transmission electron micrographs (TEM) show that the resultant materials keep mesoporous structure. Thermogravimetric analysis (TGA), X-ray photoelectron spectra (XPS), back titration, solid-state 13C CP/MAS NMR and solid-state 29Si MAS NMR confirm that the organosiloxanes were condensed as a part of the silica framework. The bifunctional sample (SO3H-MCM-41-NH2) containing amine and sulfonic acids exhibits excellent acid-basic properties, which make it possess high activity in aldol condensation reaction between acetone and various aldehydes.

 
 
 
 
281

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

282

The synthesis of barbituric acid and some of its derivatives isotopically labelled with 15N  

International Nuclear Information System (INIS)

Full text: Barbituric acid is the parent compound of a large class of barbiturates that have central nervous system depressant properties, although barbituric acid itself is not pharmacologically active. In recent years, barbituric acid derivatives have been studied as antitumor, anticancer and anti-osteoporosis agents. The aim of this paper is to present the synthesis of barbituric acid-15N, 5,5-diethylbarbituric acid-15N (Veronal-15N) and 5-ethyl-5-phenylbarbituric acid- 15N (Phenobarbitone-15N) . As isotopically labelled material we used urea-15N2, 99 at.% 15N produced at National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj-Napoca, Romania. All compounds were fully characterized by Mass Spectrometry analyses, by FT-IR Spectroscopy and RX Diffraction, and the isotopic label was determined by MS on the molecular compounds. (author)

283

Effect of Whole-Body X-Irradiation of the Synthesis of Individual Fatty Acids in Liver Slices from Normal and Fasted Rats  

DEFF Research Database (Denmark)

(1) Using (2-14C) acetate and (1-14C) butyrate as precursors, rat-liver fatty acids were synthesized in vitro and assayed by paper chromatography. (2) Whole-body x-irradiation induced a change in the synthetic pattern of hepatic fatty acids towards a relatively enhanced synthesis of palmitic acid. (3) X-irradiation and fasting seem to have opposite effects on fatty-acid synthesis. X-irradiation counteracts the drop in total synthesis and the relatively enhanced synthesis of palmitoleic acid induced by fasting. The relative enhancement of palmitic-acid synthesis mentioned under (2) stands in contrast to the effect of fasting, which specifically decreases the hepatic synthesis of palmitic acid. (4) There is a general similarity between corresponding fatty-acid patterns based on synthesis from (2-14C) acetate and (1-14C) butyrate, respectively.

Hansen, Heinz Johs. Max; Hansen, Lisbeth Grænge

1965-01-01

284

Synthesis of N,N-Bis(nonaflyl) Squaric Acid Diamide and its Application to Organic Reactions  

International Nuclear Information System (INIS)

We have developed a new strong Br?nsted acid bearing two nonaflyl groups based on the squaric acid scaffold. The Br?nsted acid 2 showed the almost same reactivity as bistriflyl squaramide 1 in Mukaiyama aldol and Michael reactions of benzaldehyde with silyl enol ether. Moreover, the utility of Br?nsted acid 2 could be expanded to carbonyl ene reaction of rac-citronellal. Further application of this new Br?nsted acid to organic reactions and to flow system reactors is currently underway in our laboratory. Br?nsted acid catalysis is one of the growing fields in modern organic synthesis.1 Although several Br?nsted acids, such as urea/thiourea, TADDOL, and phosphoric acid, have been applied to a variety of organic reactions, other Br?nsted acid scaffolds have been much less explored. Recently, Rawal et al have developed a Br?nsted acid catalyst based on squaric acid moiety and successfully applied it as a catalyst for conjugate addition of 1,3-dicarbonyl compounds to nitroolefins. More recently, we have developed a strong Br?nsted acid derived from squaric acid by introducing a strong electron withdrawing trifluoromethanesulfonyl (Tf) group and applied it to Mukaiyama aldol and Michael reaction of a variety of aldehydes, ketones, and ?,?-unsaturated ketones. As a continuing effort to develop strong Br?nsted acids based on the squaric acid scaffold, it was expected that replacement of Tf group with a longer perfluoro-alkanesulfonyl group would be able to tune the physical properties, such as solubilities in organic solvents and fluoro-philicity, without loss of reactivity. Herein, we report the development of a new Br?nsted acid based on the squaric acid scaffold carrying two nonafluorobutanesulfonyl (Nf) groups and the preliminary results of its reactivity to various organic reactions

285

Synthesis of the glucuronic acid conjugate of methylazoxymethanol.  

Science.gov (United States)

The glucuronic acid conjugate of methylazoxymethanol was synthesized by oxidizing the primary alcohol of the glucose moiety of cycasin (methylazoxymethanol-beta-D-glycopyranoside) to a carboxylic acid. The oxidation was carried out by bubbling oxygen gas through a cycasin solution in the presence of a platinum-on-carbon catalyst. A band at 1715 cm-1, not present in the cycasin infrared spectrum, appeared in the spectrum of the oxidized cycasin product, establishing the presence of a carboxylic acid group. The oxidation product is methylazoxymethanol-beta-D-glucosiduronic acid because, when hydrolyzed with Escherichia coli beta-glucuronidase, it produced methylazoxymethanol and glucuronic acid and also indicated retention of the beta-linkage of cycasin. Varying quantities of the synthesized methylazoxymethanol-glucosiduronic acid, injected into Wistar rats of both sexes and of varying weights, were not acutely toxic. The compound was mutagenic to Salmonella typhimurium when preincubated with E. coli beta-glucuronidase, but not when preincubated with bovine liver glucuronidase. PMID:455292

Matsumoto, H; Takata, R H; Komeiji, D Y

1979-08-01

286

Synthesis and pharmacological evaluation of cyclodextrin conjugate prodrug of mefenamic acid  

Directory of Open Access Journals (Sweden)

Full Text Available In the present investigation mefenamic acid prodrug of ?-cyclodextrins was synthesized. The primary hydroxy group of ?-cyclodextrins was used to block the acid group. The synthesis involved a series of protection and deprotection reaction. The ester was evaluated for stability in simulated gastric and intestinal fluid. The hydrolysis of cyclodextrin conjugate in colon is confirmed by the hydrolysis kinetics studies in rat faecal material. The ester was also evaluated for ulcerogenicity. Results of these studies established the primary aim of masking the ulcerogenic potential of free drug, by using 12-fold dose of the normal dose of mefenamic acid and equivalent doses of the ester.

Dev S

2007-01-01

287

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)

288

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. PMID:25300279

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

2014-10-31

289

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

290

Total synthesis of racemic and (R) and (S)-4-methoxyalkanoic acids and their antifungal activity.  

Science.gov (United States)

The total synthesis of 4-methoxydecanoic acid and 4-methoxyundecanoic acid in racemic and stereoselective [(R) and (S)] forms has been accomplished. For stereoselective synthesis of the compounds (S) and (R)-BINOL complexes have been used to generate the required chiral centres. The antifungal activity of these compounds has been studied against different organisms and the results were found to be impressive. The activity of the compounds in racemic and in stereoselective forms was compared. (R)-4-Methoxydecanoic acid was found to be most potent (MIC: 0.019 mg/mL against Candida albicans MTCC 227, C. albicans MTCC 4748, Aspergillus brasiliensis (niger) MTCC 281 and Issatchenkia orientalis MTCC 3020). PMID:21555164

Das, Biswanath; Shinde, Digambar Balaji; Kanth, Boddu Shashi; Kamle, Avijeet; Kumar, C Ganesh

2011-07-01

291

Role of ribonucleic acid synthesis in conjugational transfer of chromosomal and plasmid deoxyribonucleic acids.  

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A strain of Escherichia coli K-12 containing mutations that allow for the experimental control of RNA and DNA syntheses was constructed to investigate the role that RNA synthesis plays in conjugational DNA transfer when DNA replication is inhibited. The mutations possessed by this strain and its donor derivatives include: (i) thyA, which blocks synthesis of dTMP, causing a requirement for thymine; (ii) deoC, which blocks breakdown of deoxyribose 5-phosphate, permitting growth with low levels ...

Maturin, L. J.; Curtiss, R.

1981-01-01

292

Slow Proton Irradiation of Polyethylene Terephthalate  

International Nuclear Information System (INIS)

Epithermal neutrons interact with matter producing recoil protons which in turn transfer energy by ionization and by collision with nuclei. In an attempt to separate the effects produced by these various.processes foils of polyethylene terephthalate (Hostaphan, Melinex or Mylar) were irradiated with slow protons in the energy range from 2 to 12 keV and the changes of the optical absorption caused by die irradiation measured spectrophotometrically. Densely ionizing radiations (slow protons, 3.4 MeV alpha particles, and 2 MeV protons) induce in Hostaphan a sharp absorption maximum at 308 m?. At high doses of slow protons this maximum reaches a saturation value. The height of this saturation value increases with increasing proton energy. The D37 (i. e. dose to reach 63% of the saturation value) for protons from 2 to 12 keV is 4 x 1014 proton/cm2 (± 20%). To produce the maximum at 308 m? slow protons are more efficient than 3.4 MeV alpha particles (by a factor of 1.2 to 1.7) and 2 MeV protons (by a factor of 1. 7). The reason might be that slow protons with velocities appreciably smaller than v0 ( v0 = c/137 = velocity of an electron in the lowest orbit of a hydrogen atom) ionize with a higher probability than generally assumed. Irradiation with low energy protons produces also a broad absorption maximum at 250 m?, which is not observed after irradiation with 2 MeV protons (in vacuum) or with 3.4 MeV alpha particles (in helium under atmospheric pressure). At higher doses this maximum also reaches a saturation value, but this value is equal for all proton energies between 2 and 12 keV and corresponds to a D37 of 0.8 x 1014 proton/cm2. This maximum is thought to be due to a mechanism which has an appreciable efficiency only below 2 keV proton energy. The nature of this mechanism is unknown, but it may be caused either by a chemical reaction of the zero energy protons with the plastic molecules or by elastic collisions of the protons with atomic nuclei. It is remarkable, however, that this mechanism (as evident from the D37 values) is more efficient in changing the properties of Hostaphan than die ionization mechanism of densely ionizing radiation (slow protons or 2 MeV protons, respectively). The experiments described here show clearly that the energy of very slow protons which are produced by epithermal neutrons is transferred to matter not only by ionization processes but also by another mechanism occurring at low proton energies. This mechanism of energy transfer, if shown to lead to biologically important consequences may have a bearing on setting tolerance limits for epithermal neutrons. (author)

293

Synthesis and quantitative structure-property relationships of side chain-modified hyodeoxycholic acid derivatives.  

Science.gov (United States)

Bile acids have emerged as versatile signalling compounds of a complex network of nuclear and membrane receptors regulating various endocrine and paracrine functions. The elucidation of the interconnection between the biological pathways under the bile acid control and manifestations of hepatic and metabolic diseases have extended the scope of this class of steroids for in vivo investigations. In this framework, the design and synthesis of novel biliary derivatives able to modulate a specific receptor requires a deep understanding of both structure-activity and structure-property relationships of bile acids. In this paper, we report the preparation and the critical micellization concentration evaluation of a series of hyodeoxycholic acid derivatives characterized by a diverse side chain length and by the presence of a methyl group at the alpha position with respect to the terminal carboxylic acid moiety. The data collected are instrumental to extend on a quantitative basis, the knowledge of the current structure-property relationships of bile acids and will be fruitful, in combination with models of receptor activity, to design and prioritize the synthesis of novel pharmacokinetically suitable ligands useful in the validation of bile acid-responsive receptors as therapeutic targets. PMID:23999724

Sabbatini, Paola; Filipponi, Paolo; Sardella, Roccaldo; Natalini, Benedetto; Nuti, Roberto; Macchiarulo, Antonio; Pellicciari, Roberto; Gioiello, Antimo

2013-01-01

294

Synthesis and Quantitative Structure-Property Relationships of Side Chain-Modified Hyodeoxycholic Acid Derivatives  

Directory of Open Access Journals (Sweden)

Full Text Available Bile acids have emerged as versatile signalling compounds of a complex network of nuclear and membrane receptors regulating various endocrine and paracrine functions. The elucidation of the interconnection between the biological pathways under the bile acid control and manifestations of hepatic and metabolic diseases have extended the scope of this class of steroids for in vivo investigations. In this framework, the design and synthesis of novel biliary derivatives able to modulate a specific receptor requires a deep understanding of both structure-activity and structure-property relationships of bile acids. In this paper, we report the preparation and the critical micellization concentration evaluation of a series of hyodeoxycholic acid derivatives characterized by a diverse side chain length and by the presence of a methyl group at the alpha position with respect to the terminal carboxylic acid moiety. The data collected are instrumental to extend on a quantitative basis, the knowledge of the current structure-property relationships of bile acids and will be fruitful, in combination with models of receptor activity, to design and prioritize the synthesis of novel pharmacokinetically suitable ligands useful in the validation of bile acid-responsive receptors as therapeutic targets.

Antimo Gioiello

2013-08-01

295

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

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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

296

One-Pot synthesis of phosphorylated mesoporous carbon heterogeneous catalysts with tailored surface acidity  

Energy Technology Data Exchange (ETDEWEB)

Soft-templated phosphorylated mesoporous carbons with homogeneous distributions of phosphate groups were prepared by a 'one-pot' synthesis method using mixtures of phosphoric acid with hydrochloric, or nitric acids in the presence of Pluronic F127 triblock copolymer. Adjusting the various ratios of phosphoric acid used in these mixtures resulted in carbons with distinct adsorption, structural and surface acidity properties. The pore size distributions (PSDs) from nitrogen adsorption at -196 C showed that mesoporous carbons exhibit specific surface areas as high as 551 m{sup 2}/g and mesopores as large as 13 nm. Both structural ordering of the mesopores and the final phosphate contents were strongly dependent on the ratios of H{sub 3}PO{sub 4} in the synthesis gels, as shown by transmission electron microscopy (TEM), X-ray photoelectron (XPS) and energy dispersive X-ray spectroscopy (EDS). The number of surface acid sites determined from temperature programmed desorption of ammonia (NH{sub 3}-TPD) were in the range of 0.3-1.5 mmol/g while the active surface areas are estimated to comprise 5-54% of the total surface areas. Finally, the conversion temperatures for the isopropanol dehydration were lowered by as much as 100 C by transitioning from the least acidic to the most acidic catalysts surface.

Fulvio, Pasquale F [ORNL; Mahurin, Shannon Mark [ORNL; Mayes, Richard T [ORNL; Bauer, Christopher [ORNL; Wang, Xiqing [ORNL; Veith, Gabriel M [ORNL; Dai, Sheng [ORNL

2012-01-01

297

A new and direct synthesis of lactic acid from acrylic acid using an excimer laser with high intensity  

International Nuclear Information System (INIS)

A new and direct method of XeF (351 nm) laser irradiation of acrylic acid 1 solution containing H2O2 are described for the chemical synthesis of lactic acid 2. Increase in the yield strongly depended on the irradiation dose and H2O2 feeding rate, and the formation of 2 showed the quantum yield, 0.3, and the selectivity, 50%, at the maximum yield. Product analysis indicated that OH radicals formed with high density by the laser-photolysis of H2O2 are equally bonded to the carbons of ?- and ?-positions of 1 to produce 2 and 3-hydroxy propanoic acid with ratio of 1 to 1. (author)

298

Effect of nerve growth factor on the synthesis of amino acids in PC12 cells  

International Nuclear Information System (INIS)

Radioactive short-chain fatty acids preferentially label glutamine relative to glutamate in brain due to compartmentation of glutamine and glutamate. To determine whether this phenomenon occurs in a single cell culture model, we examined the effect of fatty acid chain length on the synthesis as well as pool size of selected amino acids in rat pheochromocytoma PC12 cells, a cell culture model of the large glutamate compartment in neurons. Intracellular 14C-amino acids were quantitated by HPLC, and the incorporation of [U-14C]-glucose, [1-14C]-butyrate, [1-14C]-octanoate, and [1-14C]-palmitate into five amino acids was measured in native and NGF-treated PC12 cells. NGF pretreatment decreased the intracellular concentration of amino acids as did addition of fatty acids but these effects were not additive. Specific activities of amino acids in native cells labelled by 14C-octanoate were 1,300 DPM/nmol, 490 DPM/nmol, 200 DPM/nmol, and 110 DPM/nmol for glutamate, aspartate, glutamine, and serine, respectively. No radioactivity was detected in alanine. Similar specific activities were noted when 14C-butyrate was the precursor; however, there was at least 5-fold less if 14C-palmitate was the precursor. Pretreatment of cells with NGF decreased the specific activity of amino acids by 25-65%. Specific activities of amino acids synthesized from 14C-glucose decreased in the following order: glutamate, 1,640 DPM/nmol; aspartate, 1,210 DPM/nmol; alanine, 580 DPM/nmol; glutamine, 275 DPM/nmol; and serine, 80 DPM/nmol for native cells. NGF pretreatment decreased the specific activities of glutamate and glutamine, but not of the other 3 amino acids. The preferred precursor for glutamate synthesis in native PC12 cells was glucose followed by octanoate, butyrate and palmitate (16:6:3:1)

299

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

300

Ultraviolet induction of prophage lambda during inhibition of deoxyribonucleic acid synthesis by hydroxyurea  

International Nuclear Information System (INIS)

Hydroxyurea inhibited synthesis of certain deoxyribonucleic acid (DNA) precursors and caused the cessation of DNA synthesis. It did not cause induction of lambda. Superinfection of an irradiated lysogen with lambda ind- could prevent induction, but the percentage of cells protected decreased as the time between irradiation and superinfection increased. The presence of hydroxyurea did not increase the time during which cells could be rescued by superinfection. The accumulation of DNA precursors after ultraviolet or ionizing radiation was not necessary for the induction of lambda prophage to occur

 
 
 
 
301

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

302

An inproved synthesis of 24- 13C-labeled bile acids using formyl esters and a modified lead tetraacetate procedure  

International Nuclear Information System (INIS)

An improved synthesis of 24-13C-labeled bile acids has been achieved using formyl derivatives of bile acids and a modified lead tetraacetate procedure. The formylated bile acids were degraded by lead tetraacetate and lithium chloride to formylated 23-chloronorcholanes in 72 to 83% yield. Formylated 23-chloronorcholanes were converted to nitriles in dimethylformamide, which were then hydrolyzed to obtain C-24 labeled bile acids in yield of 80 to 90% of labeled sodium cyanide used. This method results in a higher yield and a purer product with less manipulation than previously reported procedures for synthesis of labeled bile acids

303

The use of supported acidic ionic liquids in organic synthesis.  

Science.gov (United States)

Catalysts obtained by the immobilisation of acidic ionic liquids (ILs) on solid supports offer several advantages compared to the use of catalytically active ILs themselves. Immobilisation may result in an increase in the number of accessible active sites of the catalyst and a reduction of the amount of the IL required. The ionic liquid films on the carrier surfaces provide a homogeneous environment for catalytic reactions but the catalyst appears macroscopically as a dry solid, so it can simply be separated from the reaction mixture. As another advantage, it can easily be applied in a continuous fixed bed reactor. In the present review the main synthetic strategies towards the preparation of supported Lewis acidic and Brønsted acidic ILs are summarised. The most important characterisation methods and structural features of the supported ionic liquids are presented. Their efficiency in catalytic reactions is discussed with special emphasis on their recyclability. PMID:24972271

Skoda-Földes, Rita

2014-01-01

304

Synthesis of [(13) C4 ]-labeled 2'-deoxymugineic acid.  

Science.gov (United States)

The phytosiderophore 2'-deoxymugineic acid (DMA) is exuded via the root system by all grasses (including important crop plants like rice, wheat and barley) to mobilize Fe(III) from soil and improve plant Fe nutrition, crucial for high crop yields. Elucidation of the biogeochemistry of 2'-deoxymugineic acid in the rhizosphere requires its quantification in minute amounts. To this end, (13) C4 -DMA was synthesized for the first time, from cheap isotopically labeled starting materials. The synthetic route utilizes l-allyl((13) C2 )glycine and l-(2-(13) C)azetidine ((13) C)carboxylic acid as versatile labeled building blocks. The title compound was recently used as an internal standard for analysis of soil and plant samples allowing the first accurate quantification of DMA in these matrices by means of LC-MS/MS. It is furthermore used in tracer experiments investigating biodegradation of DMA in soil. PMID:25385205

Walter, Martin R; Artner, Daniel; Stanetty, Christian

2014-11-01

305

Succinct synthesis of beta-amino acids via chiral isoxazolines.  

Science.gov (United States)

beta-Amino acids are important synthetic targets due to their presence in a wide variety of natural products, pharmaceutical agents, and mimics of protein structural motifs. While beta-amino acids containing geminal substitution patterns have enormous potential for application in these contexts, synthetic challenges to the stereoselective preparation of this class of compound have thus far limited more complete studies. We present here a straightforward method employing chiral isoxazolines as key intermediates to access five different beta-amino acid structural types with excellent selectivity. Of particular note is the use of this approach to prepare highly substituted cis-beta-proline analogues. The ready access to these diversely substituted compounds is expected to facilitate future studies of the structure and function of this important class of molecules. PMID:15826175

Fuller, Amelia A; Chen, Bin; Minter, Aaron R; Mapp, Anna K

2005-04-20

306

Amino acids in a Fischer Tropsch type synthesis  

Science.gov (United States)

One postulation is described for the presence of organic compounds in meteorites which states that they were formed during the condensation of the solar nebula. A viable laboratory simulation of these conditions can be modeled after the industrial Fischer Tropsch reaction, which is known to produce organic compounds called hydrocarbons. In this simulation, a mixture of carbon monoxide, hydrogen and ammonia is heated in the presence of iron meteorite. The reaction products for amino acids, a class of organic compounds important to life, were examined. A large number of these compounds is found in meteorites and other chemical evolution experiments, but only small quantities of a few amino acids were found in the present simulation work. These results are at odds with the existing literature in which many amino acids were reported.

Brown, D. L.; Lawless, J. G.

1974-01-01

307

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)

308

Thiamine pyrophosphate requirement for o-succinylbenzoic acid synthesis in Escherichia coli and evidence for an intermediate.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Cell-free extracts of various strains of Escherichia coli synthesize the menaquinone biosynthetic intermediate o-succinylbenzoic acid (OSB) when supplied with chorismic acid, 2-ketoglutaric acid, and thiamine pyrophosphate (TPP). To assay for OSB synthesis, 2-[U-14C]ketoglutaric acid was used as substrate, and the synthesized OSB was examined by radiogas chromatography (as the dimethyl ester). [U-14C]Shikimic acid also gave rise to radioactive OSB if the cofactors necessary for enzymatic conv...

Meganathan, R.; Bentley, R.

1983-01-01

309

[Enzymatic synthesis of saccharide and saccharide alcohol fatty acid esters].  

Science.gov (United States)

Conditions for esterification in tert-butanol using fatty acid as acy1 donor and saccharides or saccharide alcohols as acy1 acceptors, immobilized lipase from Candida sp. 1619 as biocatalyst were investigated. Optimal temperature and pH for esterication were 40 degrees C-45 degrees C and 5.5-7.5, respectively. Among the 13 acy1 donors compared, the best ones are the linoleic acid and oleic acid. The similar conversion degree was obtained when using saturated fatty acids with carbon chain length from C8 to C22. Among the 23 saccharides and saccharide alcohols compared, D-fructose, D-Xylose, trehalose, D-sorbitol, xylitol, mannitol isopropyidoneglucofruranose and alpha-methylglucopyranoside showed much higher esterification degree than other acy1 acceptors. In addition, the reaction degree of saccharide alcohols were substantially higher than that of the corresponding saccharides. The conversion was enhanced greatly when the molar ratio of acy1 donor to acy1 acceptor was higher than 2 to 1. In the case of using sorbitol and loeic acid as substrates, the reaction was carried out in 100 ml conical flask and the reaction system consisted of 3.0 mmol oleic acid(0.85 g), 0.2 mmol sorbitol(0.036 g), 3 mL tert-butanol, 30 mg immobilized lipase(600 u), shaken at 40 degrees C. After reaction for 48 h, more than 90% of sorbitol was esterified based on equal molar of substrates. The products were identified TLC as monoester and diester. PMID:12548944

Kou, X; Xu, J

2000-04-01

310

SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF OXIME ESTERS FROM DIHYDROCUMIC ACID  

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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

311

Synthesis and properties of catalysts prepared from silicomolybdovanadium heteropoly acid  

International Nuclear Information System (INIS)

Catalytic properties of samples prepared of silicomolybdovanadium heteropoly acid (HPA) have been investigated. The massive catalyst is shown to be comparatively low effective in the reaction of acrolein oxidation to acrylic acid. Impregnation of coarse-dispersed silica gel by the HPA solution results in the formation of active and selective catalyst, whereas low-active catalyst of deep oxidation is formed on the base of high-dispersed silica gel. The obtained data are explained by the formation and stabilization of different forms of vanadium- and molybdenum-containing compounds on the carrier surface

312

Amino acid chirons: a tool for asymmetric synthesis of heterocycles.  

Science.gov (United States)

As a result of their easy availability in enantiomerically enriched form and their possession of synthetically transformable diverse functional groups, amino acids have been extensively used by synthetic organic and medicinal chemists as a chiral pool for access to heterocycles (monocycles, bicycles or polycycles, either bridged or fused). This review describes the syntheses of diverse asymmetric heterocycles with various membered rings (n = 3-9) followed by benzo or heteroannulated ones, for the period from 1996 to Dec. 2013. It details solution phase synthetic methodologies in which the naturally occurring ?-amino acid is incorporated, totally or partially, into the final product. PMID:24989176

Singh, Priyanka; Samanta, Krishnananda; Das, Sanjit Kumar; Panda, Gautam

2014-09-01

313

Synthesis and complex forming property of phosphor acid derivatives  

International Nuclear Information System (INIS)

Full text:With the aim to get new effective and selective extra gents of noble and non-ferrous metals from acid solution and industrial sewage, research of the dependence of 'structure effectiveness' the various phosphor acid derivatives with logical changeable structure (thio phosphor acids, derivatives of dialkoxythiophosphor, O-alkyl-methylphosphon, alkylphenylphosphon, diphenylphosphine acids also 4 methyl-1,3,2 dioxaphosphorinane) which contain different functional groups, the remains of heterocyclic amines and alkaloids, new derivatives of some analytical reagents were synthesized. The structure of synthesized compounds is approved by the results of IR-, PMR-, mass-spectrum analyze. Researching mass-spectrum decay of synthesized phosphor acid derivatives we defined that differing from O-dihexyl-S-propargyl-benzylthio phosphat, mass spectrum decay of O-dialkyl-S-(piperdynobutin-2-il)thio phosphat is characterized by the appearing [M-H]+ ions and during the decay ions with high intensiveness are formed. Fragmentation of M+ O-alkyl-O-(aminoalkyl)phenylphosphonate proceeds in various directions and characterized with the great number of phosphor containing ions, the possession of the second phenyl radical in the molecule of diphenylphosphon acid derivatives changes the fragmentation of molecular ion of diphenylphosphon acid derivatives. The process of extraction of noble (Au, Ag, Pt, Pd, Os) metals from hydrochloric-sulphur-nitrogen acid medium was analyzed by radioactive indicator's method. It was noticed that structure, strength, conformation of compounds, the temperature, of acid medium (0,1-10 M) and the nature of acids (HCL, H2SO4, HNO3) could have strong influence to the effectiveness of metal extraction. During the research of metals extraction from pure solutions we can see the followings: 1) There are such substances, which can be used as effective group reagent towards the Au, Ag and Pd. 2) Derivatives with acetylene extract ions of gold from medium of HCl better and ions of silver from medium H2SO4. 3) If we complicate the structure of heterocyclic amine it can have positive influence to extraction of silver as the result of transition from morpholine to salsolidyn we can achieve the rise of effectiveness the extraction 2-5 times, but the branching of O-alkyl link between phosphoric parts and remains of hetero atom leads to the reduction of extraction effectiveness 2-5 times. Analyses of metal's extraction from technological solutions show that effective phosphor organic extra gents are: a) Lengthening of O-alkyl radicals in compounds molecule leads to the rise of effective extraction so Au as Ag. b) By the method of variation the length of O-alkyl and structure of main radical of phosphor acid derivatives we can derive ions of gold from silver. c) There are such compounds, which extract ions of Pt, Os, Au, and Ag from technological solution effectively. We worked out methods of defining the contest of metals in factory sewage

314

Influence of light on the free amino acid content and ?-aminobutyric acid synthesis in Brassica juncea seedlings.  

Science.gov (United States)

Glutamate decarboxylase (GAD; EC 4.1.1.15) is an important enzyme in ?-aminobutyric acid (GABA) biosynthesis. Here we report the influence of light on amino acid accumulation and investigate the molecular mechanism by which light influences GABA biosynthesis at the seedling stage of two mustard (Brassica juncea) cultivars (green-leaf and purple-leaf). Gene expression profiles of four GAD-encoding genes (GAD1, GAD2, GAD4a, and GAD4b) and their impact on GABA biosynthesis were analyzed. Light exerted an obvious influence on amino acid accumulation in mustard seedlings. GAD gene expression was also significantly regulated by light/dark or dark treatment, which differentially regulated GABA biosynthesis in B. juncea seedlings. High-performance liquid chromatography (HPLC) revealed that the seeds of purple cultivars contain a higher amount of free amino acids and GABA than do the seeds of green cultivars. After seed germination, however, the accumulation of free amino acids peaked in dark-treated seedlings on day 9 in both cultivars, whereas GABA synthesis peaked at 9 days under light conditions. This study may provide a foundation for understanding the effect of light on amino acids, particularly GABA biosynthesis in Brassica plants. PMID:23909820

Li, Xiaohua; Kim, Yeon Bok; Uddin, Md Romij; Lee, Sanghyun; Kim, Sun-Ju; Park, Sang Un

2013-09-11

315

INHIBITION OF RIBONUCLEIC ACID SYNTHESIS IN NEWCASTLE DISEASE VIRUS-INFECTED CELLS BY PUROMYCIN AND 6-AZAURIDINE.  

Science.gov (United States)

Wilson, D. E. (Rensselaer Polytechnic Institute, Troy, N.Y.), and P. LoGerfo. Inhibition of ribonucleic acid synthesis in Newcastle disease virus-infected cells by puromycin and 6-azauridine. J. Bacteriol. 88:1550-1555. 1964.-Puromycin and 6-azauridine were used to inhibit protein and ribonucleic acid (RNA) synthesis during Newcastle disease virus replication. Viral RNA, measured by the incorporation of uridine-2-C(14), increased rapidly 6 to 7 hr after infection and reached a peak at 12 hr. Viral RNA synthesis was inhibited by puromycin added at the time of infection or at any time up to 4 hr after infection, but not thereafter. 6-Azauridine (3 mg/ml) inhibited over 90% of the viral RNA synthesis and inhibited protein synthesis to a small extent. Infected cells synthesized more viral RNA than did untreated controls when exposed to azauridine alone for 5 hr, followed by puromycin alone for 9 hr. It was concluded that immediately after virus infection, virus-specific proteins, which are necessary for viral RNA synthesis, were synthesized. Virus-specific protein synthesis may occur even when viral RNA synthesis is greatly inhibited. After virus-specific protein synthesis has taken place, viral RNA synthesis may take place when protein synthesis is almost totally inhibited. PMID:14240936

WILSON, D E; LOGERFO, P

1964-12-01

316

Synthesis of some labelled non-proteinogenic amino acids  

International Nuclear Information System (INIS)

In this chapter methods are presented for preparing isotopically labeled non-proteinogenic amino acids labeled with the carbon isotopes carbon-14, -13, -11, with sulfur-35, selenium-75, nitrogen-15 and the hydrogen isotopes tritium and deuterium. 260 refs.; 8 tabs

317

Design, synthesis and biological evaluation of novel betulinic acid derivatives  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Tumor, is one of the major reason for human death, due to its widespread occurrence. Betulinic acid derivatives have attracted considerable attention as cancer chemopreventive agents and also as cancer therapeutics. Many of its derivatives inhibit the growth of human cancer cell lines by triggering apoptosis. With this background, we planned to synthesize a series of betulinic acid derivatives to assess their antiproliferation efficacy on human cancer cell lines. Results A series of novel betulinic acid derivatives were designed and synthesized as highlighted by the preliminary antitumor evaluation against MGC-803, PC3, A375, Bcap-37 and A431 human cancer cell lines in vitro. The pharmacological results showed that some of the compounds displayed moderate to high levels of antitumor activities with most of new exhibiting higher inhibitory activities compared to BA. The IC50 values of compound 3c on the five cancer cell lines were 2.3, 4.6, 3.3, 3.6, and 4.3 ?M, respectively. Subsequent fluorescence staining and flow cytometry analysis (FCM indicated that compound 3c could induce apoptosis in MGC-803 and PC3 cell lines, and the apoptosis ratios reached the peak (37.38% and 33.74% after 36 h of treatment at 10 ?M. Conclusions This study suggests that most of betulinic acid derivatives could inhibit the growth of human cancer cell lines. Furthermore, compound 3c could induce apoptosis of cancer cells.

Yang Shengjie

2012-11-01

318

Synthesis of l-Ascorbic Acid Lactone Derivatives.  

Science.gov (United States)

A small focused library which comprised of l-AA lactone derivatives was built with a facile method. This reported method was optimized by modifying the acidity of the solvent. As a result, 12 l-AA lactones were synthesized. Among these lactones, lactones 8-12 were new compounds. The cytotoxicity of these synthetic compounds were investigated. PMID:24955300

Shao, Li-Dong; Wu, Ya-Nan; Xu, Jun; He, Juan; Zhao, Yu; Peng, Li-Yan; Li, Yan; Yang, Yu-Rong; Xia, Cheng-Feng; Zhao, Qin-Shi

2014-06-01

319

Enzymatic synthesis of Fatty hydroxamic Acid derivatives based on palm kernel oil.  

Science.gov (United States)

Fatty hydroxamic acid derivatives were synthesized using Lipozyme TL IM catalyst at biphasic medium as the palm kernel oil was dissolved in hexane and hydroxylamine derivatives were dissolved in water: (1) N-methyl fatty hydroxamic acids (MFHAs); (2) N-isopropyl fatty hydroxamic acids (IPFHAs) and (3) N-benzyl fatty hydroxamic acids (BFHAs) were synthesized by reaction of palm kernel oil and N-methyl hydroxylamine (N-MHA), N-isopropyl hydroxylamine (N-IPHA) and N-benzyl hydroxylamine (N-BHA), respectively. Finally, after separation the products were characterized by color testing, elemental analysis, FT-IR and 1H-NMR spectroscopy. For achieving the highest conversion percentage of product the optimum molar ratio of reactants was obtained by changing the ratio of reactants while other reaction parameters were kept constant. For synthesis of MFHAs the optimum mol ratio of N-MHA/palm kernel oil = 6/1 and the highest conversion was 77.8%, for synthesis of IPFHAs the optimum mol ratio of N-IPHA/palm kernel oil = 7/1 and the highest conversion was 65.4% and for synthesis of BFHAs the optimum mol ratio of N-BHA/palm kernel oil = 7/1 and the highest conversion was 61.7%. PMID:25134767

Jahangirian, Hossein; Haron, Md Jelas; Yusof, Nor Azah; Silong, Sidik; Kassim, Anuar; Rafiee-Moghaddam, Roshanak; Peyda, Mazyar; Gharayebi, Yadollah

2011-01-01

320

Novel Enzymatic Synthesis of 3-hydroxybutyric Acid Oligomerswith Inserted Lactobionic Acid Moieties  

Digital Repository Infrastructure Vision for European Research (DRIVER)

3-Hydroxybutyric acid and lactobionic acid yielded linear and cyclic oligomers in a lipase-catalyzedcondensation polymerization reaction, performed at 80°C in bulk and organic solvent systems. Novozyme435 was the most efficient biocatalyst, and a mixture of t-butanol and dimethylsulfoxide in 80:20 (v/v) ratioprovided the highest copolymer conversions. The highest degree of polymerization reached 7 in case ofcopolymers with inserted lactobionic acid moiety and 11 for the 3-hydroxybutyric acid...

Kakasi-zsurka, S.; Todea, A.; But, A.; Paul, C.; Boeriu, C. G.; Nagv, A.; Davidescu, C. M.; Peter, F.

2011-01-01

 
 
 
 
321

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

322

Squalene mono-oxygenase, a key enzyme in cholesterol synthesis, is stabilized by unsaturated fatty acids.  

Science.gov (United States)

SM (squalene mono-oxygenase) catalyses the first oxygenation step in cholesterol synthesis, immediately before the formation of the steroid backbone at lanosterol. SM is an important control point in the pathway, and is regulated at the post-translational level by accelerated cholesterol-dependent ubiquitination and proteasomal degradation, which is associated with the accumulation of squalene. Using model cell systems, we report that SM is stabilized by unsaturated fatty acids. Treatment with unsaturated fatty acids such as oleate, but not saturated fatty acids, increased protein levels of SM or SM-N100-GFP (the first 100 amino acids of SM fused to GFP) at the post-translational level and partially overcame cholesterol-dependent degradation, as well as reversing cholesterol-dependent squalene accumulation. Maximum stabilization required activation of fatty acids, but not triacylglycerol or phosphatidylcholine synthesis. The mechanism of oleate-mediated stabilization appeared to occur through reduced ubiquitination by the E3 ubiquitin ligase MARCH6. Stabilization of a cholesterol biosynthetic enzyme by unsaturated fatty acids may help maintain a constant cholesterol/phospholipid ratio. PMID:24840124

Stevenson, Julian; Luu, Winnie; Kristiana, Ika; Brown, Andrew J

2014-08-01

323

Intensification of esterification of acids for synthesis of biodiesel using acoustic and hydrodynamic cavitation.  

Science.gov (United States)

Cavitation results in conditions of turbulence and liquid circulation in the reactor which can aid in eliminating mass transfer resistances. The present work illustrates the use of cavitation for intensification of biodiesel synthesis (esterification) reaction, which is mass transfer limited reaction considering the immiscible nature of the reactants, i.e., fatty acids and alcohol. Esterification of fatty acid (FA) odour cut (C(8)-C(10)) with methanol in the presence of concentrated H(2)SO(4) as a catalyst has been studied in hydrodynamic cavitation reactor as well as in the sonochemical reactor. The different reaction operating parameters such as molar ratio of acid to alcohol, catalyst quantity have been optimized under acoustic as well as hydrodynamic cavitating conditions in addition to the optimization of the geometry of the orifice plate in the case of hydrodynamic cavitation reactors. Few experiments have also been carried out with other acid (lower and higher)/methanol combination viz. caprylic acid and capric acids with methanol with an aim of investigating the efficacy of cavitation for giving the desired yields and also to quantify the degree of process intensification that can be achieved using the same. It has been observed that ambient operating conditions of temperature and pressure and reaction times of 90% conversion (mol%). This clearly establishes the efficacy of cavitation as an excellent way to achieve process intensification of the biodiesel synthesis process. PMID:17544315

Kelkar, Mandar A; Gogate, Parag R; Pandit, Aniruddha B

2008-03-01

324

Synthesis and curing of alkyd enamels based on ricinoleic acid  

Directory of Open Access Journals (Sweden)

Full Text Available 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 ricinoleic acid were formulated by calculation on alkyd constant. Alkyds were characterized by FTIR and by the determination of acid and hydroxyl numbers. Then synthesized alkyds were made into baking enamels by mixing with melamine-formaldehyde resins (weight ratio of 70:30 based on dried mass. Two types of commercial melamine resins were used: threeisobutoxymethyl melamine-formaldehyde resin (TIMMF and hexamethoxymethyl melamine resin (HMMMF. Prepared alkyd/melamine resin mixtures were cured in a differential scanning calorimeter (DSC under non-isothermal mode. Apparent degree of curing as a function of temperature was calculated from the curing enthalpies. Kinetic parameters of curing were calculated using Freeman-Carroll method. TIMMF resin is more reactive with synthesized alkyds than HMMMF resin what was expected. Alkyd resin with 30 wt% of ricinoleic acid is slightly more reactive than alkyd with 40 wt% of ricinoleic acid, probably because it has the high contents of free hydroxyl and acid groups. The gel content, Tg, thermal stability, hardness, elasticity and impact resistance of coated films cured at 150°C for 60 min were measured. Cured films show good thermal stability since the onset of films thermal degradation determined by thermogravimetric analysis (TGA is observed at the temperatures from 281 to 329°C. Films based on alkyd 30 are more thermal stable than those from alkyd 40, with the same melamine resin. The type of alkyd resin has no significant effect on the gel content and the hardness of film. Hardness of cured film increases with increasing of Tg. The values of the films elasticity are satisfied for all prepared samples and are independent on the type of alkyd or melamine resin. The impact resistances of coated films are very high.

Jovi?i? Mirjana C.

2010-01-01

325

Synthesis and physical properties of estolide ester using saturated Fatty Acid and ricinoleic Acid.  

Science.gov (United States)

A study was conveyed to produce estolide ester using ricinoleic acid as the backbone. The ricinoleic acid reacted with saturated fatty acid from C8-C18. These reactions were conducted under vacuum at 60°C for 24?h without solvent. The reaction used acid catalyst, sulphuric acid. The new saturate ricinoleic estolide esters show superior low-temperature properties (-52 ± 0.08°C) and high flash point (>300°C). The yield of the neat estolide esters ranged from 52% to 96%. The viscosity range was 51 ± 0.08 to 86 ± 0.01?cp. These new saturated estolide esters were also compared with saturated branched estolide esters. PMID:22007150

Salimon, Jumat; Nallathamby, Neeranjini; Salih, Nadia; Abdullah, Bashar Mudhaffar

2011-01-01

326

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)

327

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

Energy Technology Data Exchange (ETDEWEB)

The majority of folates existing in nature are of the pteroylpolyglutamyl form and are unable to support Lactobacillus casei growth until the gamma-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).

Ferenz, C.R.; Graham, D.Y. (Baylor Univ., Houston, TX (USA). Coll. of Medicine)

1989-07-01

328

Evaluating the coupling efficiency of phosphorylated amino acids for SPOT synthesis.  

Science.gov (United States)

A high demand of interest concerning binding assays to study the consequences of posttranscriptional phosphorylation may be addressed by peptide array-based methods. A crucial factor for de novo chemical approaches to generate such arrays is the possibility to rationally permutate phosphorylation events along a huge number of sequences. The simple principle behind this advantage is the stepwise synthesis of peptides, which allows the incorporation of either phosphorylated or nonphosphorylated derivates at serine, threonine, and tyrosine positions. In spite of several reported applications of phosphopeptide arrays, there is, to our best knowledge, no reported analysis of the efficiency of the involved techniques. Here, we analyze different coupling conditions to introduce phosphoamino acids in standard SPOT synthesis. Our results clearly indicate that EEDQ is the preferable activator and can also be used in fully automated SPOT synthesis. PMID:18816512

Tapia, Victor; Ay, Bernhard; Triebus, Julia; Wolter, Eike; Boisguerin, Prisca; Volkmer, Rudolf

2008-12-01

329

Synthesis and Thermal Properties of Amino Acids Ionic Liquids (AAILS  

Directory of Open Access Journals (Sweden)

Full Text Available Ionic Liquids (ILs are organic salts with low melting points (below 100°C and have been widely promoted as “green solvents” due to their non volatility which results in low impact on the environment and health. Natural occurring amino acids, which are easily obtained, biocompatible and biodegradable, are considered as alternative anions for ILs. Four Amino Acids Ionic Liquids (AAILs have been synthesized by using 4-vinylbenzyltrimethylammonium, [VBTMA] as the cation and glycine, alanine, serine and proline as the anions. The ILs were characterized by Nuclear Magnetic Resonance (NMR and Fourier Transform Infrared Spectroscopy (FTIR. The thermal degradation behavior was measured by Thermogravimetric Analysis (TGA and glass transition temperature measured by Differential Scanning Coulometry (DSC. The result showed that VBTMA Pro gives the highest thermal stability with 178.29°C.

M. Shahrom

2014-01-01

330

Improved synthesis of sucrose fatty acid monoesters under ultrasonic irradiation.  

Science.gov (United States)

Sucrose fatty acid esters were synthesized by the transesterification of sucrose with aliphatic esters under ultrasound irradiation in good yield (73%). The optimum reaction conditions for the transesterification reaction include a molar ratio of sucrose to fatty acid ethyl ester of 2:1 and the use of a 13%mol anhydrous K(2)CO(3) catalyst. The optimum reaction temperature was set at 70 degrees C, the optimum reaction time was 2h, and the optimum reaction pressure was 11kPa. The reaction had excellent monoester selectivity. The proportion of monoester (6-monoester+6'-monoester) in the purified products was up to 92-95% via flash column chromatography over silica gel, the ratios of 6-monoester/6'-monoester are 2.1-2.7, and the sucrose monoesters were identified by HPLC-MS, NMR and IR. PMID:19819179

Huang, Dan; Jiang, Xue; Zhu, Hao; Fu, Xiaorong; Zhong, Kangrong; Gao, Weidong

2010-02-01

331

Enzymatic synthesis of palm olein-based fatty thiohydroxamic acids.  

Science.gov (United States)

Fatty thiohydroxamic acids (FTAs) have been successfully synthesized from palm olein and thiohydroxamic acid by a one-step lipase catalyzed reaction. The use of immobilized lipase (Lipozyme RMIM) as the catalyst for the preparation reaction provides an easy isolation of the enzyme from the products and other components in the reaction mixture. The FTAs were characterized using Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance ((1)H NMR) technique and elemental analysis. The highest conversion percentage (95 %) was obtained when the process was carried out for 30 hours using urea to palm oil ratio of 6.0: 1.0 at 40 °C. The method employed offers several advantages such as renewable and abundant of the raw material, simple reaction procedure, environmentally friendly process and high yield of the product. PMID:20972356

Al-Mulla, Emad A Jaffar; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa Bt; Rahman, Mohd Zaki Ab

2010-01-01

332

Synthesis of hydroxy acids of dinorcholane and 5?-cholane  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Uma mistura diastereomérica (55:45) de 3-oxo-23,24-dinorcol-4-en-22-hydroxi ácidos (4A e 4B) foi sintetizada a partir de 3-oxo-23,24-dinorcol-4-en-22-al (1) em 3 etapas. Similarmente, 3-oxo-5?-cholano-24-hidroxi ácido (9) foi sintetizado a partir de 5?-cholano-3?,24-diol (5) em 4 etapas. Dados espec [...] troscópicos completos para estes compostos são apresentados. Abstract in english A diastereomeric mixture (55:45) of 3-oxo-23,24-dinorchol-4-en-22-hydroxy acids (4A and 4B) was synthesized from 3-oxo-23,24-dinorchol-4-en-22-al (1) in 3 steps. Similarly, 3-oxo-5?-cholane-24-hydroxy acid (9) was synthesized from 5?-cholane-3?,24-diol (5) in 4 steps. Full spectroscopic data for the [...] se compounds are presented.

L., Nahar; A. B., Turner; S. D., Sarker.

333

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

Science.gov (United States)

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

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

2013-07-17

334

Synthesis and characterization of solid 2-methoxycinnamylidenepyruvic acid  

International Nuclear Information System (INIS)

The 2-methoxycinnamylidenepyruvic acid (2-MeO-HCP) was synthesized and characterized for nuclear magnetic resonance (1H and 13C NMR), mass spectrometry (MS), Infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The application of DSC for purity determination is well documented in literature and is used in the analysis of pure organic compounds. The molecular geometry and vibrational frequencies of 2-MeO-HCP have been calculated. (author)

335

Encapsulated di-2-ethylhexylphosphoric acid: synthesis, dispersity and extraction properties  

International Nuclear Information System (INIS)

Encapsulation of di-2-ethylhexylphosphoric acid was carried out by ionic complex of gelatine with cetyltrimonium bromide. Dispersity of obtained microcapsules at various extractant and oil phase contents was determined by optical microscopy and dynamic light scattering measurements. It was found that kinetic parameters and efficiency of iron removal from aqueous medium by encapsulated extractant is more attractive in comparison with the results of liquid or membrane extraction. (authors)

336

Liquid-Phase Synthesis of Cyanuric Acid from Urea  

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Full Text Available 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

2010-03-01

337

Synthesis and curing of alkyd enamels based on ricinoleic acid  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

338

Synthesis and characterization of solid 2-methoxycinnamylidenepyruvic acid  

Energy Technology Data Exchange (ETDEWEB)

The 2-methoxycinnamylidenepyruvic acid (2-MeO-HCP) was synthesized and characterized for nuclear magnetic resonance ({sup 1}H and {sup 13}C NMR), mass spectrometry (MS), Infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The application of DSC for purity determination is well documented in literature and is used in the analysis of pure organic compounds. The molecular geometry and vibrational frequencies of 2-MeO-HCP have been calculated. (author)

Carvalho, C.T. de; Siqueira, A.B.; Pivatto, M.; Ionashiro, M. [UNESP, Araraquara, SP (Brazil). Inst. de Quimica]. E-mail: massaoi@iq.unesp.br; Ionashiro, E.Y. [Universidade Federal de Goias (UFG), Goiania, GO (Brazil). Inst. de Quimica

2008-10-15

339

Synthesis of isoalkyl pyosphonic acid (1-methyl) heptyl monoester  

International Nuclear Information System (INIS)

A new extractant,named isoalkyl phosphonic acid(1-methyl)heptyl monoester(Chinese trademark 5709), was synthesized by using saturated hydrocarbon, phosphorus trichloride and 1-methylheptanol as raw materials through a series of chemical reactions. The synthetic conditions of the extractant are studied systematically. The synthetic process is practical, the quality of the extractant is reliable. The reagent has excellent performances of separating cobalt from high nickel level sulphate solution and can purify nickel electrolyte. (authors)

340

Recent approaches towards the asymmetric synthesis of ?,?-disubstituted ?-amino acids  

DEFF Research Database (Denmark)

The class of alpha,alpha-disubstituted alpha-amino acids has gained considerable attention in the past decades and continues doing so. The ongoing interest in biological and chemical properties of the substance class has inspired the development of many new methodologies for their asymmetric construction, which have not found their way into the general focus of organic chemistry yet. The aim of this review is to provide an overview of the developments in the field since 1998.

Vogt, Henning

2007-01-01

 
 
 
 
341

Effect of atrazine herbicide on growth, photosynthesis, protein synthesis, and fatty acid composition in the unicellular green alga Chlorella kessleri.  

Science.gov (United States)

Sublethal atrazine concentrations induced a general inhibition on growth, photosynthesis, and dark respiration in the green alga Chlorella kessleri. 14C-protein hydrolysate indicated a maximum incorporation level by 5 microM atrazine after 48 hr. Progressive reduction in protein synthesis was associated with increasing herbicide concentration at all experimental periods. The herbicide had preferential effect on the associated fatty acid composition of total and phospholipids. After 24 and 48 hr the herbicide stimulated fatty acids synthesis at concentrations where photosynthesis was inhibited. Meanwhile, stearic and miristic acids disappeared at 15 microM after 24 hr and the total polyunsaturated fatty acids were not affected after 48 hr. Fatty acid synthesis was sensitive to treatment at 72 hr by 5 and 10 microM atrazine, whereas the total saturated fatty acids were completely inhibited. PMID:7534691

el-Sheekh, M M; Kotkat, H M; Hammouda, O H

1994-12-01

342

Loss of nuclear receptor SHP impairs but does not eliminate negative feedback regulation of bile acid synthesis.  

Science.gov (United States)

The in vivo role of the nuclear receptor SHP in feedback regulation of bile acid synthesis was examined. Loss of SHP in mice caused abnormal accumulation and increased synthesis of bile acids due to derepression of rate-limiting CYP7A1 and CYP8B1 hydroxylase enzymes in the biosynthetic pathway. Dietary bile acids induced liver damage and restored feedback regulation. A synthetic agonist of the nuclear receptor FXR was not hepatotoxic and had no regulatory effects. Reduction of the bile acid pool with cholestyramine enhanced CYP7A1 and CYP8B1 expression. We conclude that input from three negative regulatory pathways controls bile acid synthesis. One is mediated by SHP, and two are SHP independent and invoked by liver damage and changes in bile acid pool size. PMID:12062084

Kerr, Thomas A; Saeki, Shigeru; Schneider, Manfred; Schaefer, Karen; Berdy, Sara; Redder, Thadd; Shan, Bei; Russell, David W; Schwarz, Margrit

2002-06-01

343

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)

344

Synthesis, crystal structure and computational studies of 4-nitrobenzylphosphonic acid  

Science.gov (United States)

4-Nitrobenzylphosphonic acid (1a) has been synthesized and structurally characterized by vibrational spectroscopy (IR and Raman) and single-crystal X-ray diffraction. Additionally, Hirshfeld surface analysis and computational methods have been used to compare the intermolecular interactions in the crystal structures of 1a and its carboxylic analogue, 4-nitrobenzylcarboxylic acid (4-NBCA). The crystal structure analysis of 1a has revealed that the acid molecules are extended into helical chains along the b axis using one of the hydrogen bonds established between phosphonic groups. The second (P)Osbnd H⋯O(P) hydrogen bond cross-links the inversion-related chains to form a thick monolayer with phosphonic groups arranged inwards and aromatic rings outwards. The nitro groups serve to link the neighbouring monolayers by weak Csbnd H⋯O(N) hydrogen bonds. Computations have confirmed the great contribution of electrostatic interactions for the crystal lattice stability. The cohesive energy, computed for the crystal structure of 1a exceeds 200 kJ mol-1 in magnitude and is nearly twice as large as that of 4-NBCA. The calculated cohesive energy values have been further related to the results of thermal analyses.

Wilk, Magdalena; Jarzembska, Katarzyna N.; Janczak, Jan; Hoffmann, Józef; Videnova-Adrabinska, Veneta

2014-09-01

345

Overexpression of malate dehydrogenase in transgenic alfalfa enhances organic acid synthesis and confers tolerance to aluminum.  

Science.gov (United States)

Al toxicity is a severe impediment to production of many crops in acid soil. Toxicity can be reduced through lime application to raise soil pH, however this amendment does not remedy subsoil acidity, and liming may not always be practical or cost-effective. Addition of organic acids to plant nutrient solutions alleviates phytotoxic Al effects, presumably by chelating Al and rendering it less toxic. In an effort to increase organic acid secretion and thereby enhance Al tolerance in alfalfa (Medicago sativa), we produced transgenic plants using nodule-enhanced forms of malate dehydrogenase and phosphoenolpyruvate carboxylase cDNAs under the control of the constitutive cauliflower mosaic virus 35S promoter. We report that a 1.6-fold increase in malate dehydrogenase enzyme specific activity in root tips of selected transgenic alfalfa led to a 4.2-fold increase in root concentration as well as a 7.1-fold increase in root exudation of citrate, oxalate, malate, succinate, and acetate compared with untransformed control alfalfa plants. Overexpression of phosphoenolpyruvate carboxylase enzyme specific activity in transgenic alfalfa did not result in increased root exudation of organic acids. The degree of Al tolerance by transformed plants in hydroponic solutions and in naturally acid soil corresponded with their patterns of organic acid exudation and supports the concept that enhancing organic acid synthesis in plants may be an effective strategy to cope with soil acidity and Al toxicity. PMID:11743127

Tesfaye, M; Temple, S J; Allan, D L; Vance, C P; Samac, D A

2001-12-01

346

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

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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

347

Synthesis of an A-E gambieric acid subunit with use of a C-glycoside centered strategy.  

Science.gov (United States)

This paper describes our synthesis of the A-E subunit of gambieric acid (GA) in addition to the synthesis of the A-ring and the C-E tricycle. The use of an enol ether-olefin RCM strategy to couple the A and C-E subunits and, in the process, generate the B-ring is noteworthy. PMID:17469838

Roberts, Scott W; Rainier, Jon D

2007-05-24

348

Stress-corrosion cracking of indium tin oxide coated polyethylene terephthalate for flexible optoelectronic devices  

International Nuclear Information System (INIS)

Stress corrosion cracking of transparent conductive layers of indium tin oxide (ITO), sputtered on polyethylene terephthalate (PET) substrates, is an issue of paramount importance in flexible optoelectronic devices. These components, when used in flexible device stacks, can be in contact with acid containing pressure-sensitive adhesives or with conductive polymers doped in acids. Acids can corrode the brittle ITO layer, stress can cause cracking and delamination, and stress-corrosion cracking can cause more rapid failure than corrosion alone. The combined effect of an externally-applied mechanical stress to bend the device and the corrosive environment provided by the acid is investigated in this work. We show that acrylic acid which is contained in many pressure-sensitive adhesives can cause corrosion of ITO coatings on PET. We also investigate and report on the combined effect of external mechanical stress and corrosion on ITO-coated PET composite films. Also, it is shown that the combination of stress and corrosion by acrylic acid can cause ITO cracking to occur at stresses less than a quarter of those needed for failure with no corrosion. In addition, the time to failure, under ? 1% tensile strain can reduce the total time to failure by as much as a third

349

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

350

Chitosan/poly (vinyl pyrollidone) coatings improve the antibacterial properties of poly(ethylene terephthalate)  

International Nuclear Information System (INIS)

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.

351

Regioselectivity in the Ring Opening of Epoxides for the Synthesis of Aminocyclitols from D-(--Quinic Acid  

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Full Text Available Efficient syntheses of four aminocyclitols are reported. Each synthesis is accomplished in eight steps starting from D-(--quinic acid. The key step involves a highly regioselective ring opening of epoxides by sodium azide.

Shu-Yu Yang

2012-04-01

352

Synthesis of ( sup 3 H) aminocyclopropane carboxylic acid (ACC) as a ligand for the glycine B receptor  

Energy Technology Data Exchange (ETDEWEB)

The synthesis of ({sup 3}H)Aminocyclopropane carboxylic acid at high specific activity and high purity is described. The compound has been developed as a specific ligand for the Glycine-B binding site. (author).

Dappen, M.S.; Markos, C.S.; Gresk, C.J. (Searle (G.D.) and Co., Skokie, IL (USA)); Cordi, A.A. (Searle, Monsanto Life Sciences Research Center, St Louis, MO (USA))

1990-07-01

353

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

354

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

355

Waste polyethylene terephthalate as an aggregate in concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 de Brito

2013-01-01

356

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

357

In situ synthesis of peptide nucleic acids in porous silicon for drug delivery and biosensing.  

Science.gov (United States)

Peptide nucleic acids (PNA) are a unique class of synthetic molecules that have a peptide backbone and can hybridize with nucleic acids. Here, a versatile method has been developed for the automated, in situ synthesis of PNA from a porous silicon (PSi) substrate for applications in gene therapy and biosensing. Nondestructive optical measurements were performed to monitor single base additions of PNA initiated from (3-aminopropyl)triethoxysilane attached to the surface of PSi films, and mass spectrometry was conducted to verify synthesis of the desired sequence. Comparison of in situ synthesis to postsynthesis surface conjugation of the full PNA molecules showed that surface mediated, in situ PNA synthesis increased loading 8-fold. For therapeutic proof-of-concept, controlled PNA release from PSi films was characterized in phosphate buffered saline, and PSi nanoparticles fabricated from PSi films containing in situ grown PNA complementary to micro-RNA (miR) 122 generated significant anti-miR activity in a Huh7 psiCHECK-miR122 cell line. The applicability of this platform for biosensing was also demonstrated using optical measurements that indicated selective hybridization of complementary DNA target molecules to PNA synthesized in situ on PSi films. These collective data confirm that we have established a novel PNA-PSi platform with broad utility in drug delivery and biosensing. PMID:24949894

Beavers, Kelsey R; Mares, Jeremy W; Swartz, Caleb M; Zhao, Yiliang; Weiss, Sharon M; Duvall, Craig L

2014-07-16

358

Rheb-TOR signaling promotes protein synthesis, but not glucose or amino acid import, in Drosophila  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The Ras-related GTPase, Rheb, regulates the growth of animal cells. Genetic and biochemical tests place Rheb upstream of the target of rapamycin (TOR protein kinase, and downstream of the tuberous sclerosis complex (TSC1/TSC2 and the insulin-signaling pathway. TOR activity is regulated by nutritional cues, suggesting that Rheb might either control, or respond to, nutrient availability. Results We show that Rheb and TOR do not promote the import of glucose, bulk amino acids, or arginine in Drosophila S2 cells, but that both gene products are important regulators of ribosome biogenesis, protein synthesis, and cell size. S2 cell size, protein synthesis, and glucose import were largely insensitive to manipulations of insulin signaling components, suggesting that cellular energy levels and TOR activity can be maintained through insulin/PI3K-independent mechanisms in S2 cell culture. In vivo in Drosophila larvae, however, we found that insulin signaling can regulate protein synthesis, and thus may affect TOR activity. Conclusion Rheb-TOR signaling controls S2 cell growth by promoting ribosome production and protein synthesis, but apparently not by direct effects on the import of amino acids or glucose. The effect of insulin signaling upon TOR activity varies according to cellular type and context.

de la Cruz Aida

2007-03-01

359

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

360

Non-isothermal crystallization behavior of biodegradable poly(butylene succinate-co-terephthalate (PBST copolyesters  

Directory of Open Access Journals (Sweden)

Full Text Available Non-isothermal crystallization and subsequent melting of biodegradable poly(bu-tylene succinate-co-terephthalate copolyesters with different butylene terephtha-late contents were investigated by differential scanning calorimetry measurements. Differential scanning calorimetry crystallization curves revealed that butylene terephthalate contents of poly(butylene succinate-co-terephthalate copolyesters had an identical effects on the onset, peak and final crystallization temperatures. Subsequent differential scanning calorimetry melting curves implied that both PBST-10 and PBST-70 copolyesters had the narrow distribution of lamellar thickness, while the PBST-50 copolyester showed much wider distribution.

Zhang Jie

2012-01-01

 
 
 
 
361

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%

362

Synthesis and characterization of organic-inorganic hybrids formed between conducting polymers and crystalline antimonic acid  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper we report the synthesis and characterization of novel organic-inorganic hybrid materials between the crystalline antimonic acid (CAA) and two conductive polymers: polypyrrole and polyaniline. The hybrids were obtained by in situ oxidative polymerization of monomers by the Sb(V) present in the pyrochlore-like CAA structure. The materials were characterized by infrared and Raman spectroscopy, X-ray diffraction, cyclic voltammetry, CHN elemental analysis and electronic paramagnetic...

Beleze Fábio A.; Zarbin Aldo J. G.

2001-01-01

363

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

International Nuclear Information System (INIS)

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)

364

N-Heterocyclic carbene/Brønsted acid cooperative catalysis as a powerful tool in organic synthesis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The interplay between metals and N-heterocyclic carbenes (NHCs) has provided a window of opportunities for the development of novel catalytic strategies within the past few years. The recent successful combination of Brønsted acids with NHCs has added a new dimension to the field of cooperative catalysis, enabling the stereoselective synthesis of functionalized pyrrolidin-2-ones as valuable scaffolds in heterocyclic chemistry. This Commentary will briefly highlight the concept of N-heterocyc...

Vreese, Rob; D’hooghe, Matthias

2012-01-01

365

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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; Shaikh, Javed A.; Gazge Muiz; Vijay Mane; Khursheed Ahmed

2013-01-01

366

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

367

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

368

ULTRASOUND-MEDIATED SYNTHESIS PYRAZINE-2-CARBOXYLAMINO ACIDS AND DIPEPTIDES AS POTENT INSECTICIDAL AND  

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Full Text Available A series of pyrazine-2-carboxylamino acids and dipeptides were synthesized by solution-phase peptide synthesis by conventional as well as by using an ultrasonic bath-type sonicator. The reaction time was drastically reduced by sonication with good yields. The synthesized compounds were characterized by IR, 1H NMR and Mass spectral analysis and evaluated for anthelmintic and insecticidal activities.

Malipeddi Venkataramana

2010-09-01

369

Two synthetic routes for the asymmetric synthesis of [?-11C]amino acids with high enantiomeric purities  

International Nuclear Information System (INIS)

An asymmetric synthesis for some [beta-11C]-amino acids by highly stereoselective alkylations of imidazolidinone glycine derivatives with carbon-11 labelled alkyl iodides has been developed. It has been used to prepare labelled alanine and phenylalanine enriched in the L- or D- form. A chiral glycine Ni-complex was employed in the asymmetric synthesis of L-[beta-11C]-amino acids

370

Electrodialysis synthesis of concentrated solutions of perrhenic acid  

Science.gov (United States)

The presented results demonstrate the possibility of electrodialysis production of concentrated solutions of perrhenic acid (HReO4 concentration >400 g/l). KReO4 is used as a precursor. The investigations are performed in a three-chamber electrodialysis cell in a continuous mode. The optimal processing parameters are as follows: the current is 3-5 A, the voltage is 30-40 V, and the anode chamber temperature is 20-25°C. Grade AR-0 ammonium perrhenate is precipitated from the obtained HReO4 solution.

Palant, A. A.; Bryukvin, V. A.; Levin, A. M.; Reshetova, O. V.

2011-03-01

371

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

372

Liquid-phase synthesis of cyanuric acid from urea.  

Science.gov (United States)

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 degrees C to 220 degrees 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. PMID:20336020

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

2010-03-01

373

N-Heterocyclic carbene/Brønsted acid cooperative catalysis as a powerful tool in organic synthesis  

Directory of Open Access Journals (Sweden)

Full Text Available The interplay between metals and N-heterocyclic carbenes (NHCs has provided a window of opportunities for the development of novel catalytic strategies within the past few years. The recent successful combination of Brønsted acids with NHCs has added a new dimension to the field of cooperative catalysis, enabling the stereoselective synthesis of functionalized pyrrolidin-2-ones as valuable scaffolds in heterocyclic chemistry. This Commentary will briefly highlight the concept of N-heterocyclic carbene/Brønsted acid cooperative catalysis as a new and powerful methodology in organic chemistry.

Rob De Vreese

2012-03-01

374

A new rapid, regiospecific synthesis of 15-(p-[sup(123)I]=iodophenyl)pentadecanoic acid  

International Nuclear Information System (INIS)

The triazene derivative of 15-(p-aminophenyl)pentadecanoic acid, 1-[4-(15-oxopentadecanoyl)phenyl]-3,3-(1,5-pentanediyl)triazene was synthetized as a new substrate which is readily converted to 15-(p-iodophenyl)-pentadecanoic acid (IPP). Iodine-123-labelled IPP is prepared in approx. 30% yield in less than 30 min by reaction of triazene with no-carrier added Hsup(123)I, obtained by decay of sup(123)Xe. This rapid, regiospecific synthesis represents an improved method for the preparation of [sup(123)I]IPP. (author)

375

Synthesis of gamma-aminobutyric acid analogs based on carbohydrate scaffolds.  

Science.gov (United States)

Gamma-aminobutyric acid analogs based on sugar scaffolds were prepared in six to nine steps starting from D-glucal and D-galactal. The key step in the synthesis is the Vilsmeier-Haack reaction that affords the corresponding 2-C-formyl glycal on treatment with DMF and POCl(3). Oxidation of the aldehyde and reduction of the 4-azido group provided the corresponding GABA analog. Acylamide and tetrazole analogs were also prepared as the bioisosteres of the carboxylic acid. PMID:20400064

Zhong, Ming; Meng, Xiang-Bao; Li, Zhong-Jun

2010-06-16

376

Synthesis and Physico-Chemical Properties of New Tetraethylammonium-Based Amino Acid Chiral Ionic Liquids  

Directory of Open Access Journals (Sweden)

Full Text Available This paper reports the synthesis of a series of new tetraethylammonium-based amino acid chiral ionic liquids (CILs. Their physico-chemical properties, including melting point, thermal stability, viscosity and ionic conductivity, have been comprehensively studied. The obtained results indicated that the decomposition for these salts proceeds in one step and the temperature of decomposition (Tonset is in the range of 168–210 °C. Several new CILs prepared in this work showed high ionic conductivity compared to the amino acid ionic liquids (AAILs found in the literature.

Mohd Basyaruddin Abdul Rahman

2010-04-01

377

Synthesis, discovery, and quantitation of dihomo-isofurans: biomarkers for in vivo adrenic acid peroxidation.  

Science.gov (United States)

The growing importance of lipidomics, and the interest of non-enzymatic metabolites of polyunsaturated fatty acids (PUFAs) prompted us to initiate the synthesis of novel dihomo-IsoF compounds. Such metabolites of adrenic acid, the main PUFA in white matter, were synthesized using a divergent approach based on an orthoester cyclization. LC-MS/MS investigation on pig brains showed the potential of this novel biomarker for the first time, as a powerful new tool for brain lipid peroxidation assessment. PMID:24839059

de La Torre, Aurélien; Lee, Yiu Yiu; Oger, Camille; Sangild, Per Torp; Durand, Thierry; Lee, Jetty Chung-Yung; Galano, Jean-Marie

2014-06-10

378

Synthesis, characterization, and crystal structure of 2-iodo-3,4,5-trimethoxybenzoic acid  

Science.gov (United States)

This work describes the synthesis of 2-iodo-3,4,5-trimethoxybenzoic acid. The combination of iodine and silver trifluoroacetate (AgTFA) reagents was used successfully for the iodination of 3,4,5-trimetoxybenzoic acid. To improve the efficiency of the synthetic process a significant modification on the experimental design was also performed. The main structural features of the obtained aryl iodide were investigated by a single crystal X-ray diffraction analysis, FTIR, 1H and 13C NMR spectroscopy.

Kolev, Iliyan N.; Petrova, Svetlana P.; Nikolova, Rositsa P.; Dimowa, Louiza T.; Shivachev, Boris L.

2013-02-01

379

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)

380

Synthesis and bioactivity of analogues of the marine antibiotic tropodithietic acid  

DEFF Research Database (Denmark)

Tropodithietic acid (TDA) is a structurally unique sulfur-containing antibiotic from the Roseobacter clade bacterium Phaeobacter inhibens DSM 17395 and a few other related species. We have synthesised several structural analogues of TDA and used them in bioactivity tests against Staphylococcus aureus and Vibrio anguillarum for a structure-activity relationship (SAR) study, revealing that the sulfur-free analogue of TDA, tropone-2-carboxylic acid, has an antibiotic activity that is even stronger than the bioactivity of the natural product. The synthesis of this compound and of several analogues is presented and the bioactivity of the synthetic compounds is discussed.

Rabe, Patrick; Klapschinski, Tim A.

2014-01-01

 
 
 
 
381

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

382

Microwave-Assisted Synthesis of New Substituted Anilides of Quinaldic Acid  

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Full Text Available In this study a one step method for the preparation of substituted anilides of quinoline-2-carboxylic acid was developed. This efficient innovative approach is based on the direct reaction of an acid or ester with substituted anilines using microwave irradiation. The optimized method was used for the synthesis of a series of eighteen substituted quinoline-2-carboxanilides. The molecular structure of N-(4-bromophenylquinoline-2-carboxamide as a model compound was determined by single-crystal X-ray diffraction. It crystallizes in the monoclinic space group with four molecules within the unit cell and the total structure of the compound can be described as “a slightly screwed boat”.

Josef Jampilek

2012-01-01

383

Sequential enzymatic synthesis and separation of 13N-L-glutamic acid and 13N-L-alanine  

International Nuclear Information System (INIS)

The sequential enzymatic synthesis and separation of 13N-L-glutamic acid and 13N-L-alanine are described. Basically, that involves the synthesis of 13N-L-glutamic acid by one enzyme, the transamination of the labeled glutamic acid to form 13N-L-alanine by a second enzyme, and the separation of the two amino acids by rapid column chromatography. The 13N-L-alanine was evaluated in animals by imaging and tissue distribution studies and showed good potential as a pancreatic imaging agent

384

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

Science.gov (United States)

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 catalysis. Using the solid acid K-10 montmorillonite or the superacidic perfluorinated resinsulfonic acid Nafion-H, a wide variety of trifluoromethylated imines have been synthesized using the above methods. The products have been isolated in good to excellent yields and high selectivities. This new environmentally friendly synthetic methodology provides significantly higher yields than traditional methods during relatively short reaction times for the preparation of the target compounds. PMID:21949445

Abid, Mohammed; Savolainen, Markku; Landge, Shainaz; Hu, Jinbo; Surya Prakash, G. K.; Olah, George A.

2009-01-01

385

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese [...] 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

386

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese [...] 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.

387

Synthesis and pharmacology of 3-hydroxy-delta2-isoxazoline-cyclopentane analogues of glutamic acid  

DEFF Research Database (Denmark)

The synthesis and pharmacology of two potential glutamic acid receptor ligands are described. Preparation of the bicyclic 3-hydroxy-delta2-isoxazoline-cyclopentane derivatives (+/-)-7 and (+/-)-8 was accomplished via 1,3-dipolar cycloaddition of bromonitrile oxide to suitably protected 1-amino-cyclopent-3-enecarboxylic acids. Their structure was established using a combination of 1H NMR spectroscopy and molecular mechanics calculations carried out on the intermediate cycloadducts (+/-)-11 and (+/-)-12. Amino acid derivatives (+/-)-7 and (+/-)-8 were assayed at ionotropic and metabotropic glutamic acid receptor subtypes and their activity compared with that of trans-ACPD and cis-ACPD. The results show that the replacement of the omega-carboxylic group of the model compounds with the 3-hydroxy-delta2-isoxazoline moiety abolishes or reduces drastically the activity at the metabotropic glutamate receptors. Conversely, on passing from cis-ACPD to derivative (+/-)-8, the agonist activity at NMDA receptors is almostunaffected.

Conti, P; De Amici, M

2002-01-01

388

Novel sol-gel synthesis of acidic MgF(2-x)(OH)(x) materials.  

Science.gov (United States)

Novel magnesium fluorides have been prepared by a new fluorolytic sol-gel synthesis for fluoride materials based on aqueous HF. By changing the amount of water at constant stoichiometric amount of HF, it is possible to tune the surface acidity of the resulting partly hydroxylated magnesium fluorides. These materials possess medium-strength Lewis acid sites and, by increasing the amount of water, Brønsted acid sites as well. Magnesium hydroxyl groups normally have a basic nature and only with this new synthetic route is it possible to create Brønsted acidic magnesium hydroxyl groups. XRD, MAS NMR, TEM, thermal analysis, and elemental analysis have been applied to study the structure, composition, and thermal behaviour of the bulk materials. XPS measurements, FTIR with probe molecules, and the determination of N(2)/Ar adsorption-desorption isotherms have been carried out to investigate the surface properties. Furthermore, activity data have indicated that the tuning of the acidic properties makes these materials versatile catalysts for different classes of reactions, such as the synthesis of (all-rac)-[alpha]-tocopherol through the condensation of 2,3,6-trimethylhydroquinone (TMHQ) with isophytol (IP). PMID:19006145

Wuttke, Stefan; Coman, Simona M; Scholz, Gudrun; Kirmse, Holm; Vimont, Alexandré; Daturi, Maro; Schroeder, Sven L M; Kemnitz, Erhard

2008-01-01

389

Adding a functional handle to nature's building blocks: the asymmetric synthesis of ?-hydroxy-?-amino acids.  

Science.gov (United States)

?-Hydroxy-?-amino acids are not only used by synthetic chemists but are also found in natural products, many of which show anti-microbial or anti-cancer properties. Over the past 30?years, chemists have searched for many asymmetric routes to these useful building blocks. Initial attempts to synthesize these compounds utilized chiral auxiliaries and the reactions of glycine equivalents with aldehydes to form two stereocenters in one step. Other methods with the formation of specific intermediates or that were aimed at a specific amino acid have also been investigated. Asymmetric hydrogenation by dynamic kinetic resolution has emerged as a high-yielding method for the synthesis of an array of modified amino acids with good stereoselectivity. More recently, amino-acid functionalization and multicomponent reactions have increased the atom economy and simplified many long and difficult routes. In this Focus Review, many of the elegant syntheses of these compounds are explored. The applications of ?-hydroxy-?-amino acids in natural-product synthesis are also mentioned. PMID:24840231

Zhang, Yinfeng; Farrants, Helen; Li, Xuechen

2014-07-01

390

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

391

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

392

Synthesis and characterization of cashew gum/acrylic acid nanoparticles  

International Nuclear Information System (INIS)

This paper describes the preparation of nanoparticles from cashew gum (CG) and acrylic acid (AA) by free radical polymerization using cerium (IV) ammonium nitrate (CAN) as an initiator. The yields of the nanoparticles (NP) obtained by varying the RCG/AA from 0.5 to 2.0 were between 65 and 40%. The FT-IR spectra of the NP samples showed bands characteristic of the cashew gum spectrum and a new band at 1560 cm-1 assigned to the stretching vibration of COO- groups of polyacrylic acid. On increasing the RCG/AA from 0.5 to 2.0 an increase in particle size was observed. The NP with an RCG/AA of 0.5 were smaller and had higher storage stability than the NP with an RCG/AA of 1.0 or 2.0. The increase in RCG/AA had no significant effect on the zeta potential of the NP in water. The NP were dried and re-dissolved in water to observe the effect of freeze-drying on particle size. For the NP with an RCG/AA of 0.5 an increase in particle size was observed from 71 to 402 nm, however, for the NP with an RCG/AA of 1.0 or 2.0 a small variation in particle diameter was noted. The behavior of the CG/AA NP was also found to be pH sensitive

393

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

394

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

395

Engineering of Saccharomyces cerevisiae for the synthesis of short chain fatty acids.  

Science.gov (United States)

Carbon feedstocks from fossilized sources are being rapidly depleted due to rising demand for industrial and commercial applications. Many petroleum-derived chemicals can be directly or functionally substituted with chemicals derived from renewable feedstocks. Several short chain organic acids may fulfill this role using their functional groups as a target for chemical catalysis. Saccharomyces cerevisiae was engineered to produce short chain carboxylic acids (C6 to C10 ) from glucose using the heterologous Homo sapiens type I fatty acid synthase (hFAS). This synthase was activated by phosphopantetheine transfereases AcpS and Sfp from Escherichia coli and Bacillus subtilis, respectively, both in vitro and in vivo. hFAS was produced in the holo-form and produced carboxylic acids in vitro, confirmed by NADPH and ADIFAB assays. Overexpression of hFAS in a yeast FAS2 knockout strain, deficient in de novo fatty acid synthesis, demonstrated the full functional replacement of the native fungal FAS by hFAS. Two active heterologous short chain thioesterases (TEs) from Cuphea palustris (CpFatB1) and Rattus norvegicus (TEII) were evaluated for short chain fatty acid (SCFA) synthesis in vitro and in vivo. Three hFAS mutants were constructed: a mutant deficient in the native TE domain, a mutant with a linked CpFatB1 TE and a mutant with a linked TEII TE. Using the native yeast fatty acid synthase for growth, the overexpression of the hFAS mutants and the short-chain TEs (linked or plasmid-based) increased in vivo caprylic acid and total SCFA production up to 64-fold (63?mg/L) and 52-fold (68?mg/L), respectively, over the native yeast levels. Combined over-expression of the phosphopantetheine transferase with the hFAS mutant resulted in C8 titers of up to 82?mg/L and total SCFA titers of up to 111?mg/L. PMID:23928901

Leber, Christopher; Da Silva, Nancy A

2014-02-01

396

Synthesis and biological activity of hydroxylated derivatives of linoleic acid and conjugated linoleic acids.  

Science.gov (United States)

Allylic hydroxylated derivatives of the C18 unsaturated fatty acids were prepared from linoleic acid (LA) and conjugated linoleic acids (CLAs). The reaction of LA methyl ester with selenium dioxide (SeO(2)) gave mono-hydroxylated derivatives, 13-hydroxy-9Z,11E-octadecadienoic acid, 13-hydroxy-9E,11E-octadecadienoic acid, 9-hydroxy-10E,12Z-octadecadienoic acid and 9-hydroxy-10E,12E-octadecadienoic acid methyl esters. In contrast, the reaction of CLA methyl ester with SeO(2) gave di-hydroxylated derivatives as novel products including, erythro-12,13-dihydroxy-10E-octadecenoic acid, erythro-11,12-dihydroxy-9E-octadecenoic acid, erythro-10,11-dihydroxy-12E-octadecenoic acid and erythro-9,10-dihydroxy-11E-octadecenoic acid methyl esters. These products were purified by normal-phase short column vacuum chromatography followed by high-performance liquid chromatography (HPLC). Their chemical structures were characterized by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance spectroscopy (NMR). The allylic hydroxylated derivatives of LA and CLA exhibited moderate in vitro cytotoxicity against a panel of human cancer cell lines including chronic myelogenous leukemia K562, myeloma RPMI8226, hepatocellular carcinoma HepG2 and breast adenocarcinoma MCF-7 cells (IC(50) 10-75 microM). The allylic hydroxylated derivatives of LA and CLA also showed toxicity to brine shrimp with LD(50) values in the range of 2.30-13.8 microM. However these compounds showed insignificant toxicity to honeybee at doses up to 100 microg/bee. PMID:19146841

Li, Zhen; Tran, Van H; Duke, Rujee K; Ng, Michelle C H; Yang, Depo; Duke, Colin C

2009-03-01

397

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

398

Aqueous organocatalyzed aldol reaction of glyoxylic acid for the enantioselective synthesis of ?-hydroxy-?-keto acids  

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N-Tosyl-(Sa)-binam-L-prolinamide is an efficient catalyst for the aqueous aldol reaction, between glyoxylic acid, as monohydrate or aqueous solution, and ketones. This reaction led to the formation of chiral ?-hydroxy-?-keto carboxylic acids in high levels of diastereo- and enantioselectivities achieving mainly anti aldol products.

Navarro Moles, Fernando Javier; Guillena Townley, Gabriela; Na?jera Domingo, Carmen

2013-01-01

399

Oxidative cleavage of erucic acid for the synthesis of brassylic acid  

Energy Technology Data Exchange (ETDEWEB)

The main focus of this work is to synthesize Brassylic Acid (BA) using oxidative cleavage of Erucic Acid (EA). Crambe (Crambe abyssinica) is an industrial oilseed grown in North Dakota. Crambe has potential as an industrial fatty acid feedstock as a source of Erucic acid (EA). It has approximately 50-60 % of EA, a C{sub 22} monounsaturated fatty acid. Oxidative cleavage of unsaturated fatty acids derived from oilseeds produces long chain (9, 11, and 13 carbon atoms) dibasic and monobasic acids. These acids are known commercial feedstocks for the preparation of nylons, polyesters, waxes, surfactants, and perfumes. Other sources of EA are Rapeseed seed oil which 50-60 % of EA. Rapeseed is grown outside USA. The oxidative cleavage of EA was done using a high throughput parallel pressure reactor system. Kinetics of the reaction shows that BA yields reach a saturation at 12 hours. H{sub 2}WO{sub 4} was found to be the best catalyst for the oxidative cleavage of EA. High yields of BA were obtained at 80 C with bubbling of O{sub 2} or 10 bar of O{sub 2} for 12 hours.

Mohammed J. Nasrullah; Pooja Thapliyal; Erica N. Pfarr; Nicholas S. Dusek; Kristofer L. Schiele; James A. Bahr

2010-10-29

400

Synthesis and characterization of agricultural controllable humic acid superabsorbent.  

Science.gov (United States)

Humic acid superabsorbent polymer (P(AA/AM-HA)) and superabsorbent polymer (P(AA/AM)) were synthesized by aqueous solution polymerization method using acrylic acid (AA), acrylamide (AM) and humic acid (HA) as raw material. The effects of N,N'-methylenebisacrylamide (MBA) crosslinking agent, potassium peroxydisulfate (KPS) initiator, reaction temperature, HA content, ratio of AA to AM, concentration of monomer and neutralization of AA on water absorption were investigated. Absorption and desorption ratios of nitrogen fertilizer and phosphate fertilizer were also investigated by determination of absorption and desorption ratio of NH4(+), PO4(3-) on P(AA/AM-HA) and P(AA/AM). The P(AA/AM-HA) and P(AA/AM) were characterized by Fourier translation infrared spectroscopy, biological photomicroscope and scanning electron microscopy (SEM). The optimal conditions obtained were as follows: the weight ratio of MBA to AA and AM was 0.003; the weight ratio of KPS to AA and AM was 0.008; the weight ratio of HA to AA was 0.1; the mole ratio of AM to AA is 0.1; the mole ratio of NaOH to AA is 0.9; the reaction temperature was 60°C. P(AA/AM-HA) synthesized under optimal conditions, has a good saline tolerance, its water absorbency in distilled water and 0.9 wt.% saline solution is 1180 g/g and 110 g/g, respectively. P(AA/AM-HA) achieves half saturation in 6.5 min. P(AA/AM-HA) is superior to P(AA/AM) on absorption of NH4(+), PO4(3-). The SEM micrograph of P(AA/AM-HA) shows a fine alveolate structure. The biological optical microscope micrograph of P(AA/AM-HA) shows a network structure. Graft polymerization between P(AA/AM) and HA was demonstrated by infrared spectrum. The P(AA/AM-HA) superabsorbent has better absorbing ability of water and fertilizer, electrolytic tolerance and fewer cost than P(AA/AM) superabsorbent. PMID:25078843

Gao, Lijuan; Wang, Shiqiang; Zhao, Xuefei

2013-12-01

 
 
 
 
401

Synthesis, kinetics and pharmacological evaluation of mefenamic acid mutual prodrug.  

Science.gov (United States)

A novel mutual prodrug (MA-P) consisting of mefenamic acid (MA) and paracetamol (P) has been synthesized as a gastrosparing NSAID, devoid of ulcerogenic side effects. The structure of synthesized drug was confirmed by elemental analysis, infrared spectroscopy, 1H NMR spectroscopy and mass spectrometry.The kinetics of ester hydrolysis was studied by HPLC at pH 2, pH 7.4 as well as in human plasma. The pharmacological activities (anti-inflammatory, analgesic and ulcerogenic) were evaluated for the synthesized drug. The ulcerogenic reduction in terms of gastric wall mucosa, hexosamine and total proteins were also measured in glandular stomach of rats. The results indicated that MA-P ester has better ulcer index than the parent drug. PMID:24147370

Shah, Kamal; Shrivastava, Sushant K; Mishra, Pradeep

2013-01-01

402

Synthesis and Antiangiogenic Activity of Novel Gambogic Acid Derivatives  

Directory of Open Access Journals (Sweden)

Full Text Available Gambogic acid (GA is in a phase II clinical trial as an antitumor and antiangiogenesis agent. In this study, 36 GA derivatives were synthesized and screened in a zebrafish model to evaluate their antiangiogenic activity and toxicity. Derivatives 4, 32, 35, 36 effectively suppressed the formation of newly grown blood vessels and showed lower toxicities than GA as evaluated by zebrafish heart rates and mortalities. They also exhibited more potent migration and HUVEC tube formation inhibiting activities than GA. Among them, 36 was the most potent one, suggesting that it may serve as a potential new antiangiogenesis candidate with low toxicity. Additionally, 36 showed comparable antiproliferative activity to HUVECs and five tumor cell lines but low cytotoxicity to LO2 cells.

Li-Juan Chen

2012-05-01

403

Synthesis and biological evaluation of oseltamivir analogues from shikimic acid.  

Science.gov (United States)

New oseltamivir analogues were designed and synthesized, starting from shikimic acid. Biological evaluation against three human cancer cell lines (KB, MCF7 and Lu-1) showed that many of them exhibited cytotoxic activity. Azides 5 are more active than the corresponding amines 6. Thus, the reduction of the azide group into amine led to the loss of cytotoxicity. The compounds with a cyclohexanemethyloxy group at C-3 were more active than the other investigated compounds belonging to the same series. This cyclohexanemethyloxy group seems to be critical for the cytotoxic activity of this class of compounds. The synthetic oseltamivir analogues 6a-e had no inhibition activity, even at the concentration of 50 microM when they were evaluated for their in vitro influenza A neuraminidase inhibitory activity by an enzymatic assay. PMID:25230508

Nguyen, Van Hung; Pham, Van Cuong; Do, Thi Thao; Mai, Huong Doan Thi; Le, Nguyen Thanh; Vu, Van Nam; Tran, Van Hieu; Nguyen, Thi Minh Hang; Dehaen, Wim; Chau, Van Minh

2014-07-01

404

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

405

Synthesis and cytotoxic evaluation of novel paraconic acid analogs.  

Science.gov (United States)

A novel class of 2,3-tri- and tetrasubstituted ?-butyrolactones analogous to paraconic acids has been synthesized in one step using a straightforward three-component reaction among aryl bromides, dimethyl itaconate and carbonyl compounds. The in vitro cytotoxic activity of representative compounds has been evaluated against a panel of human cancer cell lines (KB, HCT116, MCF7, HL60). While most molecules exhibit a low to moderate background activity on both KB and HL60 cancer cell lines, one compound shows increased antiproliferative activities against both cell lines with IC(50) values in the 10(-7)-10(-6)mol/L range. An extended evaluation indicated that this compound also inhibits PC3, SK-OV3, MCF7R and HL60R cell growth in the same fashion. PMID:22004720

Le Floch, Camille; Le Gall, Erwan; Léonel, Eric; Martens, Thierry; Cresteil, Thierry

2011-12-01

406

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

407

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

DEFF Research Database (Denmark)

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.

Faergeman, Nils J; Mandrup, Susanne

2012-01-01