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1

Synthesis of terephthalic acid by isomerization of coal acid  

Energy Technology Data Exchange (ETDEWEB)

Terephthalic acid can be obtained in the presence of a catalyst Cd{sub 3} by isomerixation of potassium salt of coal acid produced from coal oxidation. Effects of the amount of catalyst, initial pressure of CO{sub 2}, reaction temperature and reaction time were investigated. It was confirmed that WSA can be converted to terephthalic acid in the presence of a catalyst. In case of isomerizing the potassium salt of coal acids alone, the optimum conditions of isomerization were as: temperature 430 to 450{sup o}C, initial pressure of CO{sub 2} 4.0 MPa, catalyst CdCO{sub 3} 4% and reaction time 2 h. Such optimum conditions were similar to those of The isomerization by a mixture of potassium coal acids (WSA) which was equivalent to 75% of BPCA and was the effective composition of WSA. It has shown that the selectivity was good. The yield of crude TPA was about 68% if isomerization was carried out with a mixture of potassium salts of coal acid and benzoic acid at its optimum conditions. The yield of TPA was as high as 70% after being deducted from the theoretical yield of BNA dismutation, and about two times of WSA isomerization alone. The purity of the refined TPA was {le} 99%.

Zhang, Q.; Guan, J.; Zhao, S.; Guo, S. [Dalian University of Technology, Dalian (China). Inst. of Coal Chemical Engineering

2003-10-01

2

Method of drying terephthalic acid  

UK PubMed Central (United Kingdom)

The invention discloses a drying method of terephthalic acid, which comprises the following steps: 1) entering terephthalic acid slurry around the outlet of filter machine into cylinder drier or rotary steam tubular drier drying at partition-wall typed exchanging pattern to critical moisture content 2) condensing adsorbing heating turbining reacting waste gas as dried gas transmitting terephthalic acid into fluid bed drier through rotary transmitter proceeding cross flow with dried flow from steam turbine drying. The invention improves the efficiency of heat exchanging mass in the drying course, which reduces PTA energy consumption to utilize waste heat completely.

WANG LIJUN SHAO

3

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.

2009-01-01

4

PROCESSES FOR PRODUCING TEREPHTHALIC ACID  

UK PubMed Central (United Kingdom)

Processes for producing terephthalic acid are disclosed, the processes comprising combining in a reaction medium p-xylene, a solvent comprising water and one or more saturated organic acids having from 2-4 carbon atoms, and an oxygen-containing gas, at a temperature from about 135 DEG C to about 165 DEG C, in the presence of a catalyst composition comprising cobalt atoms and manganese atoms, with bromine atoms provided as a promoter. The amount of cobalt used may be from about 1 ,800 ppm to about 6,000 ppm, with respect to the total weight of the liquid in the reaction medium, and the weight ratio of cobalt to manganese may be from about 40 to about 400.; The processes according to the invention produce terephthalic acid as a precipitated reaction product, with typically no more than about 10 ppm 2,6-dicarboxyfluorenone produced, with respect to the weight of the terephthalic acid produced, or no more than about 20 ppm 2,6- dicarboxyfluorenone, with respect to the total weight of the reaction medium, per batch or upon one pass through a reactor. The terephthalic acid so produced may be further purified by one or more additional oxidation reactions, without the need for expensive hydrogenation purification processes.

SUMNER CHARLES EDWAN JR; HEMBRE ROBERT THOMAS; LANGE DAVID; LAVOIE GINO GEORGES; TENNANT BRENT ALAN; FLOYD THOMAS RICHARD; DAVENPORT BRYAN WAYNE; COMPTON DANIEL BURTS; BAYS JOSEPH NATHANIEL

5

Renal handling of terephthalic acid  

Energy Technology Data Exchange (ETDEWEB)

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

Tremaine, L.M.; Quebbemann, A.J.

1985-01-01

6

Synthesis and luminescent properties of Eu(III) complexes of 2-thienyltrifluoroacetonate, terephthalic acid and trioctylphosphine oxide  

Energy Technology Data Exchange (ETDEWEB)

This work reports the synthesis and luminescent properties of the terephthalic acid (TPA) and europium(III) (Eu(III)) with 2-thienyltrifluoroacetonate (HTTA) and trioctylphosphine oxide (TPPO), in the solid state. The new complexes Eu(TPA)(TTA)(TPPO){sub 2} and Eu{sub 2}(TPA)(TTA){sub 4}(TPPO){sub 4} were characterized by elemental analysis, infrared spectroscopy, scanning electronic microscopy and thermal stability analysis. The complexes Eu(TPA)(TTA)(TPPO){sub 2} and Eu{sub 2}(TPA)(TTA){sub 4}(TPPO){sub 4} present higher thermal stability than Eu(TTA){sub 3}(TPPO){sub 2} does. And the formation of the binuclear/polynuclear structure of the complexes appears to be responsible for the enhancement of the thermal stability. The emission spectra present narrow emission bands that arise from the {sup 5}D{sub 0}-{sup 7}F {sub J} (J = 0-4) transition of the Eu{sup 3+} ion. The spectral data of the complexes Eu(TPA)(TTA)(TPPO){sub 2} and Eu{sub 2}(TPA)(TTA){sub 4}(TPPO){sub 4} show only one sharp peak in the region of the {sup 5}D{sub 0}-{sup 7}F{sub 0} transition indicating that only one Eu(III) ion species is present in each sample. In addition, the luminescence decay curves of the complexes Eu(TPA)(TTA)(TPPO){sub 2} and Eu{sub 2}(TPA)(TTA){sub 4}(TPPO){sub 4} fit a single-exponential decay law. The values of quantum efficiencies of the emitting {sup 5}D{sub 0} level for the complexes Eu(TPA)(TTA)(TPPO){sub 2} and Eu{sub 2}(TPA)(TTA){sub 4}(TPPO){sub 4} are 26.4 and 25.6%, respectively.

Zhao, X.H. [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Green Packaging and Application Biological Nanotechnology of Hunan Province, Hunan University of Technology, Zhuzhou 412008 (China); Huang, K.L. [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)]. E-mail: klhuang@mail.csc.edu.cn; Liu, Z.G. [Key Laboratory of Green Packaging and Application Biological Nanotechnology of Hunan Province, Hunan University of Technology, Zhuzhou 412008 (China); Jiao, F.P. [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Li, Z.J. [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Hu, S.Q. [Key Laboratory of Green Packaging and Application Biological Nanotechnology of Hunan Province, Hunan University of Technology, Zhuzhou 412008 (China)

2007-06-28

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Synthesis and luminescent properties of Eu(III) complexes of 2-thienyltrifluoroacetonate, terephthalic acid and trioctylphosphine oxide  

International Nuclear Information System (INIS)

This work reports the synthesis and luminescent properties of the terephthalic acid (TPA) and europium(III) (Eu(III)) with 2-thienyltrifluoroacetonate (HTTA) and trioctylphosphine oxide (TPPO), in the solid state. The new complexes Eu(TPA)(TTA)(TPPO)2 and Eu2(TPA)(TTA)4(TPPO)4 were characterized by elemental analysis, infrared spectroscopy, scanning electronic microscopy and thermal stability analysis. The complexes Eu(TPA)(TTA)(TPPO)2 and Eu2(TPA)(TTA)4(TPPO)4 present higher thermal stability than Eu(TTA)3(TPPO)2 does. And the formation of the binuclear/polynuclear structure of the complexes appears to be responsible for the enhancement of the thermal stability. The emission spectra present narrow emission bands that arise from the 5D0-7F J (J = 0-4) transition of the Eu3+ ion. The spectral data of the complexes Eu(TPA)(TTA)(TPPO)2 and Eu2(TPA)(TTA)4(TPPO)4 show only one sharp peak in the region of the 5D0-7F0 transition indicating that only one Eu(III) ion species is present in each sample. In addition, the luminescence decay curves of the complexes Eu(TPA)(TTA)(TPPO)2 and Eu2(TPA)(TTA)4(TPPO)4 fit a single-exponential decay law. The values of quantum efficiencies of the emitting 5D0 level for the complexes Eu(TPA)(TTA)(TPPO)2 and Eu2(TPA)(TTA)4(TPPO)4 are 26.4 and 25.6%, respectively.

2007-06-28

8

Poly (ethylene terephthalate) synthesis with catalysts derived from chrysotile asbestos  

Directory of Open Access Journals (Sweden)

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

Shigeki Habaue; Yusuke Takahashi; Yu Hosogoe; Hiroshi Yamashita; Meisetsu Kajiwara

2010-01-01

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

Scientific Electronic Library Online (English)

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

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

2013-01-01

10

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

Directory of Open Access Journals (Sweden)

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

2010-01-01

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ASCORBIC ACID, TEREPHTHALATE AND NITROMETHANE STABILIZERS FOR FLUOROOLEFINS  

UK PubMed Central (United Kingdom)

The present disclosure relates to compositions comprising at least one fluoroolefin and an effective amount of a stabilizer comprising at least one ascorbic acid, terephthalate, or nitromethane, or mixtures thereof. The stabilized compositions may be useful in cooling apparatus, such as refrigeration, air-conditioning, chillers and heat pumps, as well as in applications as foam blowing agents, solvents, aerosol propellants, fire extinguishants, and sterilants.

LECK THOMAS J; MINOR BARBARA HAVILAND; NAPPA MARIO JOSEPH; MOULI NANDINI C; HOWELL JON LEE

12

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.

Suwardi; Crys Fajar Partana; Agus Salim; Dyah Anitasari

2005-01-01

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Sequential pyrolysis of plastic to recover polystyrene HCL and terephthalic acid  

Energy Technology Data Exchange (ETDEWEB)

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

Evans, Robert J. (Lakewood, CO); Chum, Helena L. (Arvada, CO)

1995-01-01

14

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1995-11-07

15

Method for preparing 2,5-diparamethylaniline terephthalic acid (DTTA)  

UK PubMed Central (United Kingdom)

The invention relates to a method for preparing 2,5-diparamethylaniline terephthalic acid (DTTA) which is prepared by using dimethyl succinate succinyl (DMSS) and 4-toluidine as raw materials. The method comprises the steps of: 1, mixing materials 2, raising the temperature for dissolving 3, carrying out condensation 4, carrying out hydrolysis oxidizing reaction 5, carrying out solid-liquid separation 6, absorbing and removing impurities 7, carrying out solid-liquid separation 8, neutralizing and acidizing 10, washing and dehydrating 11, drying and 12, crushing and packaging. The product of the DTTA is obtained by the steps. The invention has the advantages of reasonable process, high purity of products, stable quality, high yield and safe and reliable reaction process.

YAOXING CUI; GUOMAO SHI; YAQIONG WANG; WENLIN XU; GANBING YAO; HUAIHAO ZHANG

16

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; Matthias Zeller; Sherri R. Lovelace-Cameron

2012-01-01

17

Toxicity of Terephthalic Acid (TPA) Smoke Mix to Algae, Daphnia, Fathead Minnows, and Earthworms.  

Science.gov (United States)

Terephthalic Acid (TPA) is being considered as a replacement smoke for Hexachloroethane (HC). The TPA smoke mix was subjected to toxicity studies to test its effects on Daphnia magna (water flea), Selenastrum capricornutum (unicellular green algae), Pimep...

M. V. Haley N. A. Chester C. W. Kurnas W. T. Muse C. T. Phillips

1995-01-01

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Toxicological review and oral risk assessment of terephthalic acid (TPA) and its esters: A category approach.  

UK PubMed Central (United Kingdom)

Polyethylene terephthalate, a copolymer of terephthalic acid (TPA) or dimethyl terephthalate (DMT) with ethylene glycol, has food, beverage, and drinking water contact applications. Di-2-ethylhexyl terephthalate (DEHT) is a plasticizer in food and drinking water contact materials. Oral reference doses (RfDs) and total allowable concentrations (TACs) in drinking water were derived for TPA, DMT, and DEHT. Category RfD and TAC levels were also established for nine C(1)-C(8) terephthalate esters. The mode of action of TPA, and of DMT, which is metabolized to TPA, involves urinary acidosis, altered electrolyte elimination and hypercalciuria, urinary supersaturation with calcium terephthalate or calcium hydrogen terephthalate, and crystallization into bladder calculi. Weanling rats were more sensitive to calculus formation than dams. Calculi-induced irritation led to bladder hyperplasia and tumors in rats fed 1000?mg/kg-day TPA. The lack of effects at 142?mg/kg-day supports a threshold for urine saturation with calcium terephthalate, a key event for calculus formation. Chronic dietary DMT exposure in rodents caused kidney inflammation, but not calculi. Chronic dietary DEHT exposure caused general toxicity unrelated to calculi, although urine pH was reduced suggesting the TPA metabolite was biologically-active, but of insufficient concentration to induce calculi. Respective oral reference doses of 0.5, 0.5, and 0.2?mg/kg-day and total allowable drinking water concentrations of 3, 3, and 1?mg/L were derived for TPA, DMT, and DEHT. An oral RfD of 0.2?mg/kg-day for the terephthalate category chemicals corresponded to a drinking water TAC of 1?mg/L.

Ball GL; McLellan CJ; Bhat VS

2012-01-01

19

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

Directory of Open Access Journals (Sweden)

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

Doris Ribitsch; Enrique Herrero Acero; Katrin Greimel; Anita Dellacher; Sabine Zitzenbacher; Annemarie Marold; Rosario Diaz Rodriguez; Georg Steinkellner; Karl Gruber; Helmut Schwab; Georg M. Guebitz

2012-01-01

20

BIO-BASED TEREPHTHALATE POLYESTERS  

UK PubMed Central (United Kingdom)

Bio-based terephthalic acid (bio-TPA), bio-based dimethyl terephthalate (bio-DMT), and bio-based polyesters, which are produced from a biomass containing a terpene or terpenoid, such as limonene are described, as well as the process of making these products. The bio-based polyesters include poly(alkylene terephthalate)s such as bio-based poly(ethylene terephthalate) (bio-PET), bio-based poly(trimethylene terephthalate) (bio-PTT), bio-based poly(butylene terephthalate) (bio-PBT), and bio-based poly(cyclohexylene dimethyl terephthalate) (bio-PCT).

BERTI CORRADO; BINASSI ENRICO; COLONNA MARTINO; FIORINI MAURIZIO; KANNAN GANESH; KARANAM SREEPADARAJ; MAZZACURATI MARZIA; ODEH IHAB; VANNINI MICAELA

 
 
 
 
21

Bio-Based Terephthalate Polyesters  

UK PubMed Central (United Kingdom)

Bio-based terephthalic acid (bio-TPA), bio-based dimethyl terephthalate (bio-DMT), and bio-based polyesters, which are produced from a biomass containing a terpene or terpenoid, such as limonene are described, as well as the process of making these products. The bio-based polyesters include poly(alkylene terephthalate)s such as bio-based poly(ethylene terephthalate) (bio-PET), bio-based poly(trimethylene terephthalate) (bio-PTT), bio-based poly(butylene terephthalate) (bio-PBT), and bio-based poly(cyclohexylene dimethyl terephthalate) (bio-PCT).

BERTI CORRADO; BINASSI ENRICO; COLONNA MARTINO; FIORINI MAURIZIO; KANNAN GANESH; KARANAM SREEPADARAJ; MAZZACURATI MARZIA; ODEH IHAB

22

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new esterase from Thermobifida halotolerans (Thh_Est) was cloned and expressed in E. coli and investigated for surface hydrolysis of polylactic acid (PLA) and polyethylene terephthalate (PET). Thh_Est is a member of the serine hydrolases superfamily containing the -GxSxG- motif with 85–87% homolog...

Doris Ribitsch; Enrique Herrero Acero; Katrin Greimel; Anita Dellacher; Sabine Zitzenbacher; Annemarie Marold; Rosario Diaz Rodriguez

23

Determination of terephthalic acid isopropylamide in urine with a liquid chromatography/mass spectrometry (LC/MS) method.  

UK PubMed Central (United Kingdom)

A sensitive and simple liquid chromatography/mass spectrometry (LC/MS) method was developed for the determination of terephthalic acid isopropylamide, the final metabolite of procarbazine in human urine. A solid-phase extraction with C(18) cartridges was used followed by LC/MS with a single mass spectrometer (SSQ 7000 from Finnigan). Terephthalic acid isobutylamide was the internal standard. The quantification limit was 30 ng/mL in urine (6 x noise). This assay was applied for drug monitoring of terephthalic acid isopropylamide in urine after oral administration of procarbazine in children and adolescents with Hodgkin lymphomas.

Baumann F; Mauz-Körholz C; Clauss D; Borrmann S; Giannis A; Merkel N; Körholz D; Preiss R

2008-01-01

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Determination of terephthalic acid isopropylamide in urine with a liquid chromatography/mass spectrometry (LC/MS) method.  

Science.gov (United States)

A sensitive and simple liquid chromatography/mass spectrometry (LC/MS) method was developed for the determination of terephthalic acid isopropylamide, the final metabolite of procarbazine in human urine. A solid-phase extraction with C(18) cartridges was used followed by LC/MS with a single mass spectrometer (SSQ 7000 from Finnigan). Terephthalic acid isobutylamide was the internal standard. The quantification limit was 30 ng/mL in urine (6 x noise). This assay was applied for drug monitoring of terephthalic acid isopropylamide in urine after oral administration of procarbazine in children and adolescents with Hodgkin lymphomas. PMID:18200575

Baumann, F; Mauz-Körholz, C; Clauss, D; Borrmann, S; Giannis, A; Merkel, N; Körholz, D; Preiss, R

2008-01-01

25

The effect of oligomeric terminal group balance on catalyzed polycondensation of Poly(ethylene terephthalate)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Poly(ethylene terephthalate) commonly known as PET has been a commercially important polymer since its introduction in 1950s and it is mainly used in fiber and packaging industries. It is mainly produced by synthesis of terephthalic acid (TPA) and ethylene glycol (EG). For PET synthesis, at first, p...

Patel, Himanshu

26

Selective hydrogenation catalyst of aromatic aldehydes for refinement of terephthalic acid  

UK PubMed Central (United Kingdom)

The invention relates to a selective hydrogenation catalyst of aromatic aldehydes for refining of terephthalic acid. The selective hydrogenation catalyst is mainly used for solving the problems that the hydrogenation of 4-carboxy-benzaldehyde (called as 4-CBA for short) in the prior art mainly generates p-toluic acid (referred to as P-TA), the amount of hydrogen consumption is great and the operation cost is high. The selective hydrogenation catalyst adopts activated carbon as a carrier and is supported with one or more metals of palladium, ruthenium, nickel, zinc and copper, and the like therefore, the technical proposal can better solve the problems and can be used in the industrial production for hydrogenation refining of the terephthalic acid.

YANQING CHANG; RUIXIA JIANG; GUANGBIN SUN; XIAOLI ZHU

27

Method for producing 1,4 C cyclohexane diformate by hydrogenation on benzene ring of terephthalic acid  

UK PubMed Central (United Kingdom)

This invention discloses a method for preparing 1,4-cyclohexane dicarboxylic acid by hydrogenation of terephthalic acid in solvent in the presence of catalyst. The solvent is water or C1-4 fatty acid alcohol. The catalyst (80-200 mesh) is composed of Ru (0.5-10 wt%) as the active component, and Al2O3 as the carrier. The weight ratio of terephthalic acid to the solvent is 1 : (1-20), while that of the catalyst to terephthalic acid is 1 : (5-20). The hydrogenation is realized at 110-180 deg.C under 2.0-5.0 MPa for 0.5-8.0 h. Compared with present techniques, the method in this invention has such advantages as mild hydrogenation conditions, short hydrogenation time and long catalyst service life (recycleable for more than 9 times).

ZHU ZHIQING LU

28

1,4-Bis(imidazol-1-yl)benzene–terephthalic acid (1/1)  

Directory of Open Access Journals (Sweden)

Full Text Available In the title compound, C12H10N4·C8H6O4, 1,4-bis(imidazol-1-yl)benzene 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.

Shiyong Zhang; Yurong Tang; Zhihua Mao; Mingliang Li; Jingbo Lan; Xiaoyu Su

2009-01-01

29

Synthesis, crystal structure and magnetic properties of terephthalate-isophthalete- and phthalate-bridged copper (II) dinuclear complexes  

Energy Technology Data Exchange (ETDEWEB)

The ability of the dianions of the terephthalic (H{sub 2}ta), isophthalic (H{sub 2} ita) and phthalic (H{sub 2} phta) acids both to act as bridges between copper (II) ions and to mediate intramolecular exchange interactions has been investigated by single crystal X-ray diffraction and variable-temperature magnetic susceptibility measurements. (Author) 31 refs.

Cano, J.; De Munno, G.; Sanz, J.L.; Ruiz, R.; Lloret, F.; Faus, J.; Julve, M.

1997-09-01

30

Modification of N-Methyl-N-Nitrosourea initiated bladder carcinogenesis in Wistar rats by terephthalic acid  

International Nuclear Information System (INIS)

The effect of terephthalic acid (TPA) on urinary bladder carcinogenesis was examined. Male Wistar rats were initiated by injection of N-Methyl-N-Nitrosourea (MNU) (20 mg/kg b.w. ip) twice a week for 4 weeks, then given basal diet containing 5% TPA, 5% TPA plus 4% Sodium bicarbonate (NaHCO3) or 1% TPA for the next 22 weeks, and then euthanized. 5% TPA treatment induced a high incidence of urinary bladder calculi and a large amount of precipitate. Though 5% TPA plus 4% Sodium bicarbonate (NaHCO3) and 1% TPA treatment did not induce urinary bladder calculi formation, they resulted in a moderate increase in urinary precipitate. Histological examination of urinary bladder revealed that MNU-5% TPA treatment resulted in a higher incidence of simple hyperplasia, papillary or nodular hyperplasia (PN hyperplasia), papilloma and cancer than MNU control. MNU-5% TPA plus 4% Sodium bicarbonate (NaHCO3) and 1% TPA treatment increased slightly the incidence of simple hyperplasia and PN hyperplasia (not statistically significant). The major elements of the precipitate are phosphorus, potassium, sulfur, chloride, calcium and TPA. The present study indicated that the calculi induced by TPA had a strong promoting activity on urinary bladder carcinogenesis and the precipitate containing calcium terephthalate (CaTPA) may also have weak promoting activity on urinary bladder carcinogenesis

2006-01-01

31

Method for preparing 2,5-di(p-chloroanilino)-terephthalic acid (DpCTA)  

UK PubMed Central (United Kingdom)

The invention relates to a method for preparing 2,5-di(p-chloroanilino)-terephthalic acid (DpCTA). In the method, dimethyl succinyl succinate (DMSS) and p-chloroaniline (pCAN) are used as raw materials. The method comprises the following steps of: (1) proportioning and mixing (2) heating and dissolving (3) condensation reaction (4) hydrolysis oxidation reaction (5) solid-liquid separation (6) adsorption and impurity removal (7) solid-liquid separation (8) neutralization and acidification (9) solid-liquid separation (10) washing and dehydration (11) drying and (12) crushing and packing, wherein a 2,5-DpCTA product is obtained through the steps. The method has the advantages of reasonable process, high product purity, stable quality, high yield and safe and reliable reaction process.

YAOXING CUI; GUOMAO SHI; YAQIONG WANG; WENLIN XU; GANBING YAO; HUAIHAO ZHANG

32

BHET preparation with SO4<2>/MO2type solid super acidic catalyst degradation of polyethylene terephthalate  

UK PubMed Central (United Kingdom)

The invention relates to a method for using SO4<2->/MO2 type solid acid to catalyze and alcoholize polyethylene terephthalate (PET) so as to prepare bis-2-hydroxyethyl terephthalate (BHET), which is characterized in that the method takes the SO4<2->/MO2 type solid super acid as a catalyst, glycol as a solvent, and alcoholizes the PET polyester under the conditions of amount of catalyst 0.01 percent to 5.00 percent of the solvent mass, decomposition temperature of between 150DEG C and 220DEG C, pressure at 1atm, and reaction time of 1 to 8 hours. The method uses the solid-acid catalyst and has the advantages of easy separation of products, high selectivity and recycling use.

ZENGXI LI; YANQING LIU; WANG JUN; HUI WANG; FULIN JIA

33

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

Directory of Open Access Journals (Sweden)

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.; Rubim Joel C.; Realpozo Rene R.; Tavares Marina F. M.

2004-01-01

34

Correlation between iodide dosimetry and terephthalic acid dosimetry to evaluate the reactive radical production due to the acoustic cavitation activity.  

UK PubMed Central (United Kingdom)

Acoustic cavitation plays an important role in sonochemical processes and the rate of sonochemical reaction is influenced by sonication parameters. There are several methods to evaluate cavitation activity such as chemical dosimetry. In this study, to comparison between iodide dosimetry and terephthalic acid dosimetry, efficacy of sonication parameters in reactive radical production has been considered by iodide and terephthalic acid dosimetries. For this purpose, efficacy of different exposure parameters on cavitations production by 1 MHz ultrasound has been studied. The absorbance of KI dosimeter was measured by spectrophotometer and the fluorescence of terephthalic acid dosimeter was measured using spectrofluorometer after sonication. The result of experiments related to sonication time and intensity showed that with increasing time of sonication or intensity, the absorbance is increased. It has been shown that the absorbance for continuous mode is remarkably higher than for pulsing mode (p-value < 0.05). Also results show that with increasing the duty cycles of pulsed field, the inertial cavitation activity is increased. With compensation of sonication time or intensity in different duty cycles, no significant absorbance difference were observed unless 20% duty cycle. A significant correlation between the absorbance and fluorescence intensities (count) at different intensity (R = 0.971), different sonication time (R = 0.999) and different duty cycle (R = 0.967) were observed (p-value < 0.05). It is concluded that the sonication parameters having important influences on reactive radical production. These results suggest that there is a correlation between iodide dosimetry and terephthalic acid dosimetry to examine the acoustic cavitation activity in ultrasound field.

Ebrahiminia A; Mokhtari-Dizaji M; Toliyat T

2013-01-01

35

Mixed-type inhibition of tyrosinase from Agaricus bisporus by terephthalic acid: computational simulations and kinetics.  

Science.gov (United States)

Tyrosinase inhibition studies are needed due to the agricultural and medicinal applications. For probing effective inhibitors of tyrosinase, a combination of computational prediction and enzymatic assay via kinetics were important. We predicted the 3D structure of tyrosinase from Agaricus bisporus, used a docking algorithm to simulate binding between tyrosinase and terephthalic acid (TPA) and studied the reversible inhibition of tyrosinase by TPA. Simulation was successful (binding energies for Autodock4 = -1.54 and Fred2.0 = -3.19 kcal/mol), suggesting that TPA interacts with histidine residues that are known to bind with copper ions at the active site. TPA inhibited tyrosinase in a mixed-type manner with a K ( i ) = 11.01 ± 2.12 mM. Measurements of intrinsic and ANS-binding fluorescences showed that TPA induced no changes in tertiary structure. The present study suggested that the strategy of predicting tyrosinase inhibition based on hydroxyl groups and orientation may prove useful for screening of potential tyrosinase inhibitors. PMID:21562848

Yin, Shang-Jun; Si, Yue-Xiu; Chen, Yong-Fu; Qian, Guo-Ying; Lü, Zhi-Rong; Oh, Sangho; Lee, Jinhyuk; Lee, Sanghyuk; Yang, Jun-Mo; Lee, Dong-Youn; Park, Yong-Doo

2011-04-01

36

Mixed-type inhibition of tyrosinase from Agaricus bisporus by terephthalic acid: computational simulations and kinetics.  

UK PubMed Central (United Kingdom)

Tyrosinase inhibition studies are needed due to the agricultural and medicinal applications. For probing effective inhibitors of tyrosinase, a combination of computational prediction and enzymatic assay via kinetics were important. We predicted the 3D structure of tyrosinase from Agaricus bisporus, used a docking algorithm to simulate binding between tyrosinase and terephthalic acid (TPA) and studied the reversible inhibition of tyrosinase by TPA. Simulation was successful (binding energies for Autodock4 = -1.54 and Fred2.0 = -3.19 kcal/mol), suggesting that TPA interacts with histidine residues that are known to bind with copper ions at the active site. TPA inhibited tyrosinase in a mixed-type manner with a K ( i ) = 11.01 ± 2.12 mM. Measurements of intrinsic and ANS-binding fluorescences showed that TPA induced no changes in tertiary structure. The present study suggested that the strategy of predicting tyrosinase inhibition based on hydroxyl groups and orientation may prove useful for screening of potential tyrosinase inhibitors.

Yin SJ; Si YX; Chen YF; Qian GY; Lü ZR; Oh S; Lee J; Lee S; Yang JM; Lee DY; Park YD

2011-04-01

37

Anticancer studies of drug encapsulated polyethylene terephthalate-Co-polylactic acid nanocapsules.  

UK PubMed Central (United Kingdom)

OBJECTIVES: The purpose of this study was to investigate the anticancer activity of anticancer drugs (5-fluorouracil and 6-thioguanine) in polymeric nanocapsules in the presence and in the absence of gold and iron oxide nanoparticles toward Hep2 cancer cells. MATERIALS AND METHODS: MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay was used for quantitative measurements for the anticancer cell activity. Encapsulated drug in polyethylene terephthalate-polylactic acid copolymer (PET-co-PLA) nanocapsules in the presence and absence of gold and iron oxide nanoparticles were prepared via the W/O/W emulsification solvent-evaporation method. Morphology of the nanoparticles was characterized by transmission electron microscopy and scanning electron microscopy. CONCLUSION: The average size of the polymeric nanocapsules, gold nanoparticles, and iron oxide nanoparticles were found to be in range of 230-260, 18 -20 nm, 5-10 nm, respectively. The findings in this study inferred that incorporated drug in polymeric nanocapsules with gold nanoparticles and iron oxide nanoparticles show better anticancer activity when compared with encapsulated drug in polymeric nanocapsules.

Kumar KS; Kumar PS; Vijayalakshmi S

2011-04-01

38

Synthesis and characterization of azo acrylates grafted onto polyethylene terephthalate by gamma irradiation  

Energy Technology Data Exchange (ETDEWEB)

Polyethylene terephthalate (PET) films were grafted with acryloyl chloride by gamma irradiation, and the grafted films were reacted with Disperse Red 1 or 4-phenylazophenol. The films where characterized by atomic force microscopy, differential scanning calorimetry, FTIR-ATR, light polarized microscopy, elemental analysis and UV spectroscopy. The surface of the films was homogeneous, and the dye underwent trans to cis photoreaction, whereby the red films became colorless by the irradiation of UV light at room temperature.

Bucio, Emilio [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Mexico DF 04510 (Mexico)]. E-mail: ebucio@nucelares.unam.mx; Skewes, Phill [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Mexico DF 04510 (Mexico); Burillo, Guillermina [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Mexico DF 04510 (Mexico)

2005-07-01

39

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

40

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

Scientific Electronic Library Online (English)

Full Text Available 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 eletroforéticas 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 n (more) m. 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 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 a (more) nd 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.; Rubim, Joel C.; Realpozo, Rene R.; Tavares, Marina F. M.

2004-06-01

 
 
 
 
41

Defects and domain boundaries in self-assembled terephthalic acid (TPA) monolayers on CVD-grown graphene on Pt(111).  

UK PubMed Central (United Kingdom)

Self-assembly of terephthalic acid (TPA), vacuum deposited on Pt(111) supported graphene, has been investigated by scanning tunneling microscopy (STM). TPA organizes in an ordered 3 × 4 superstructure with respect to the graphene lattice. This structure is a consequence of hydrogen-bonded TPA chains that arrange in a commensurate overlayer on graphene. Due to the polycrystalline nature of graphene on Pt(111), the TPA layer exhibits various grain boundaries and dislocations. Molecular resolved STM imaging has been used to characterize these defect structures in the TPA monolayer.

Addou R; Batzill M

2013-05-01

42

Novel tripartite aromatic acid transporter essential for terephthalate uptake in Comamonas sp. strain E6.  

Science.gov (United States)

It has been suggested that a novel type of aromatic acid transporter, which is similar to the tripartite tricarboxylate transporter (TTT), is involved in terephthalate (TPA) uptake by Comamonas sp. strain E6. This suggestion was based on the presence of the putative TPA-binding protein gene, tphC, in the TPA catabolic operon. The tphC gene is essential for growth on TPA and is similar to the genes encoding TTT-like substrate-binding proteins. Here we identified two sets of E6 genes, tctBA and tpiBA, which encode TTT-like cytoplasmic transmembrane proteins. Disruption of tctA showed no influence on TPA uptake but resulted in a complete loss of the uptake of citrate. This loss suggests that tctA is involved in citrate uptake. On the other hand, disruption of tpiA or tpiB demonstrated that both genes are essential for TPA uptake. Only when both tphC and tpiBA were introduced with the TPA catabolic genes into cells of a non-TPA-degrading Pseudomonas strain did the resting cells of the transformant acquire the ability to convert TPA. From all these results, it was concluded that the TPA uptake system consists of the TpiA-TpiB membrane components and TPA-binding TphC. Interestingly, not only was the tpiA mutant of E6 unable to grow on TPA or isophthalate, it also showed significant growth delays on o-phthalate and protocatechuate. These results suggested that the TpiA-TpiB membrane components are able to interact with multiple substrate-binding proteins. The tpiBA genes were constitutively transcribed as a single operon in E6 cells, whereas the transcription of tphC was positively regulated by TphR. TPA uptake by E6 cells was completely inhibited by a protonophore, carbonyl cyanide m-chlorophenyl hydrazone, indicating that the TPA uptake system requires a proton motive force. PMID:23913423

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

2013-08-02

43

Novel tripartite aromatic acid transporter essential for terephthalate uptake in Comamonas sp. strain E6.  

UK PubMed Central (United Kingdom)

It has been suggested that a novel type of aromatic acid transporter, which is similar to the tripartite tricarboxylate transporter (TTT), is involved in terephthalate (TPA) uptake by Comamonas sp. strain E6. This suggestion was based on the presence of the putative TPA-binding protein gene, tphC, in the TPA catabolic operon. The tphC gene is essential for growth on TPA and is similar to the genes encoding TTT-like substrate-binding proteins. Here we identified two sets of E6 genes, tctBA and tpiBA, which encode TTT-like cytoplasmic transmembrane proteins. Disruption of tctA showed no influence on TPA uptake but resulted in a complete loss of the uptake of citrate. This loss suggests that tctA is involved in citrate uptake. On the other hand, disruption of tpiA or tpiB demonstrated that both genes are essential for TPA uptake. Only when both tphC and tpiBA were introduced with the TPA catabolic genes into cells of a non-TPA-degrading Pseudomonas strain did the resting cells of the transformant acquire the ability to convert TPA. From all these results, it was concluded that the TPA uptake system consists of the TpiA-TpiB membrane components and TPA-binding TphC. Interestingly, not only was the tpiA mutant of E6 unable to grow on TPA or isophthalate, it also showed significant growth delays on o-phthalate and protocatechuate. These results suggested that the TpiA-TpiB membrane components are able to interact with multiple substrate-binding proteins. The tpiBA genes were constitutively transcribed as a single operon in E6 cells, whereas the transcription of tphC was positively regulated by TphR. TPA uptake by E6 cells was completely inhibited by a protonophore, carbonyl cyanide m-chlorophenyl hydrazone, indicating that the TPA uptake system requires a proton motive force.

Hosaka M; Kamimura N; Toribami S; Mori K; Kasai D; Fukuda M; Masai E

2013-10-01

44

Amino acid synthesis deficiencies.  

UK PubMed Central (United Kingdom)

Defects in the synthesis pathways of amino acids have only been discovered in recent years and are relatively unknown to most clinicians. In this chapter disorders neurological symptoms caused by genetic defects in the synthesis of the amino acids serine, glutamine and proline are discussed. Patients with serine deficiency invariably suffer from severe neurological symptoms such as microcephaly, psychomotor retardation and intractable seizures. The same is true for patients with a defect in the synthesis of glutamine who present with hypotonia and epileptic encephalopathy. Patients with a disorder in the synthesis proline have mental retardation in combination with symptoms of connective tissue disease. All amino acids synthesis disorders, except for one of the proline defects, can be diagnosed by routine amino acid analysis. Given the fact that the disorder discussed here lead to deficiencies of amino acids opens up possibilities to treat these patients with the amino acids that can't be synthesised. Prompt recognition and treatment of amino acid synthesis disorders are of outmost importance to obtain satisfactory treatment results.

de Koning TJ

2013-01-01

45

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

International Nuclear Information System (INIS)

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.

2012-06-15

46

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

47

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

2007-04-25

48

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

UK PubMed Central (United Kingdom)

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.

Hausdorf S; Baitalow F; Seidel J; Mertens FO

2007-05-01

49

Enantioselective synthesis of paraconic acids.  

UK PubMed Central (United Kingdom)

The development of a new method for the enantioselective synthesis of disubstituted gamma-butyrolactones is reported. Based on this strategy, the total synthesis of three paraconic acids, that is (-)-roccellaric acid, (-)-nephrosteranic acid and (-)-protopraesorediosic acid, and the formal total synthesis of (-)-methylenolactocin and (-)-protolichesterinic acid is described, which are important because of their antibiotic and antitumor properties. Key steps of the synthesis are copper(I)-catalyzed asymmetric cyclopropanations of furans, highly diastereoselective Sakurai allylations, Lewis acid or Lewis base catalyzed retroaldol/lactonization cascades, and ruthenium(II)-catalyzed, intermolecular cross metathesis reactions.

Chhor RB; Nosse B; Sörgel S; Böhm C; Seitz M; Reiser O

2003-01-01

50

Enantioselective synthesis of paraconic acids.  

Science.gov (United States)

The development of a new method for the enantioselective synthesis of disubstituted gamma-butyrolactones is reported. Based on this strategy, the total synthesis of three paraconic acids, that is (-)-roccellaric acid, (-)-nephrosteranic acid and (-)-protopraesorediosic acid, and the formal total synthesis of (-)-methylenolactocin and (-)-protolichesterinic acid is described, which are important because of their antibiotic and antitumor properties. Key steps of the synthesis are copper(I)-catalyzed asymmetric cyclopropanations of furans, highly diastereoselective Sakurai allylations, Lewis acid or Lewis base catalyzed retroaldol/lactonization cascades, and ruthenium(II)-catalyzed, intermolecular cross metathesis reactions. PMID:12506382

Chhor, Rakeshwar B; Nosse, Bernd; Sörgel, Sebastian; Böhm, Claudius; Seitz, Michael; Reiser, Oliver

2003-01-01

51

One-step sonochemical synthesis of a graphene oxide-manganese oxide nanocomposite for catalytic glycolysis of poly(ethylene terephthalate)  

Science.gov (United States)

Ultrasound-assisted synthesis of a graphene oxide (GO)-manganese oxide nanocomposite (GO-Mn3O4) was conducted without further modification of GO or employing secondary materials. With the GO nanoplate as a support, potassium permanganate oxidizes the carbon atoms in the GO support and gets reduced to Mn3O4. An intensive ultrasound method could reduce the number of reaction steps and temperature, enhance the reaction rate and furthermore achieve a Mn3O4 phase. The composite was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The coverage and crystallinity of Mn3O4 were controlled by changing the ratio of permanganate to GO dispersion. The synthesized nanocomposite was used as a catalyst for poly(ethylene terephthalate) (PET) depolymerization into its monomer, bis(2-hydroxylethyl) terephthalate (BHET). The highest monomer yield of 96.4% was obtained with the nanocomposite containing the lowest amount of Mn3O4, while PET glycolysis with the Mn3O4 without GO yielded 82.7% BHET.Ultrasound-assisted synthesis of a graphene oxide (GO)-manganese oxide nanocomposite (GO-Mn3O4) was conducted without further modification of GO or employing secondary materials. With the GO nanoplate as a support, potassium permanganate oxidizes the carbon atoms in the GO support and gets reduced to Mn3O4. An intensive ultrasound method could reduce the number of reaction steps and temperature, enhance the reaction rate and furthermore achieve a Mn3O4 phase. The composite was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The coverage and crystallinity of Mn3O4 were controlled by changing the ratio of permanganate to GO dispersion. The synthesized nanocomposite was used as a catalyst for poly(ethylene terephthalate) (PET) depolymerization into its monomer, bis(2-hydroxylethyl) terephthalate (BHET). The highest monomer yield of 96.4% was obtained with the nanocomposite containing the lowest amount of Mn3O4, while PET glycolysis with the Mn3O4 without GO yielded 82.7% BHET. Electronic supplementary information (ESI) available: XPS spectra of GO-Mn3O4 A and B, EDS mapping images of GO-Mn3O4 C, AFM analysis and TEM image of Mn3O4. See DOI: 10.1039/c2nr30168g

Park, Gle; Bartolome, Leian; Lee, Kyoung G.; Lee, Seok Jae; Kim, Do Hyun; Park, Tae Jung

2012-06-01

52

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

UK PubMed Central (United Kingdom)

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.

Kenny ST; Runic JN; Kaminsky W; Woods T; Babu RP; O'Connor KE

2012-08-01

53

One-step sonochemical synthesis of a graphene oxide-manganese oxide nanocomposite for catalytic glycolysis of poly(ethylene terephthalate).  

UK PubMed Central (United Kingdom)

Ultrasound-assisted synthesis of a graphene oxide (GO)-manganese oxide nanocomposite (GO-Mn(3)O(4)) was conducted without further modification of GO or employing secondary materials. With the GO nanoplate as a support, potassium permanganate oxidizes the carbon atoms in the GO support and gets reduced to Mn(3)O(4). An intensive ultrasound method could reduce the number of reaction steps and temperature, enhance the reaction rate and furthermore achieve a Mn(3)O(4) phase. The composite was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The coverage and crystallinity of Mn(3)O(4) were controlled by changing the ratio of permanganate to GO dispersion. The synthesized nanocomposite was used as a catalyst for poly(ethylene terephthalate) (PET) depolymerization into its monomer, bis(2-hydroxylethyl) terephthalate (BHET). The highest monomer yield of 96.4% was obtained with the nanocomposite containing the lowest amount of Mn(3)O(4), while PET glycolysis with the Mn(3)O(4) without GO yielded 82.7% BHET.

Park G; Bartolome L; Lee KG; Lee SJ; Kim do H; Park TJ

2012-07-01

54

Cationised gelatin and hyaluronic acid coating enhances polyethylene terephthalate artificial ligament graft osseointegration in porcine bone tunnels.  

UK PubMed Central (United Kingdom)

PURPOSE: The aim of this study was to investigate whether cationised gelatin and hyaluronic acid (CH) coating could induce polyethylene terephthalate (PET) artificial ligament graft osseointegration in the bone tunnel. METHODS: Surface modification of PET artificial ligament graft was performed by layer-by-layer (LBL) self-assembly CH coating. Six pigs underwent anterior cruciate ligament (ACL) reconstruction on the right knees, with three pigs receiving the CH-coated PET grafts and the other three pigs non-CH-coated PET grafts as controls. They were sacrificed at three months after surgery and the graft-bone complexes were acquired for computed tomography (CT) scan and histological examination. RESULTS: CT scans showed a significant difference at the distal femoral site (p?=?0.031) or at the distal tibial site (p?=?0.0078), but no significant difference in the bone tunnel areas' enlargement at other sites (p?>?0.05) between the CH group and the control group. Histologically, application of CH coating induced new bone formation between graft and bone at three months compared with the controls at the distal site. The interface width of the CH group was significantly lower than that of the control group at the distal femoral site (p?=?0.0327) and at the distal tibial site (p?=?0.0047). CONCLUSIONS: The study has shown that CH coating on the PET artificial ligament surface has a positive biological effect in the induction of artificial ligament osseointegration within the bone tunnel at the distal site of the bone tunnel.

Cho S; Li H; Chen C; Jiang J; Tao H; Chen S

2013-03-01

55

Total synthesis of lysergic Acid.  

Science.gov (United States)

A total synthesis of lysergic acid was accomplished. Key features of our synthesis include stereoselective construction of the stereogenic centers at the allylic positions by using the Evans aldol reaction, and a sequential process with a ring-closing metathesis and an intramolecular Heck reaction to construct the C and D rings. PMID:23919892

Umezaki, Satoshi; Yokoshima, Satoshi; Fukuyama, Tohru

2013-08-06

56

Adsorption and bonding of first layer and bilayer terephthalic acid on the Cu(100) surface by high-resolution electron energy loss spectroscopy.  

UK PubMed Central (United Kingdom)

The self-assembled and highly ordered first layer of terephthalic acid on Cu(100) as well as its bilayer on the same surface are studied here using high-resolution electron energy loss spectroscopy (HREELS), Auger electron spectroscopy, and low energy electron diffraction. These experiments show completion of the first layer before growth of the second layer. HREELS measurements show that the first layer of the acid deprotonates, which is seen in the absence of the OH stretching mode for the acid groups. However, this mode is present in the bilayer structure, confirming that the deprotonation is due to a reaction with the Cu surface and suggesting that there is little mixing of the layers. It has been suggested previously that the TPA monolayer structure is stabilized by an intermolecular hydrogen bonding interaction, but we are not able to resolve any distortion of the CH stretching mode for such an interaction, but instead see evidence for direct bonding to the Cu surface.

Ge Y; Adler H; Theertham A; Kesmodel LL; Tait SL

2010-11-01

57

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; Samad Shoghpour Bayraq; Sara Sharifi; Ali Ramazani; Ali Morsali; Hadi Amiri Rudbari

2012-01-01

58

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.

2011-01-01

59

1,4-Bis(4,5-dihydro-1H-imidazol-2-yl)benzene–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-yl)benzene (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; Su-Yun Li; Chun-Xia Ren; Xin Wang; Lu-De Lu

2009-01-01

60

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.

2012-01-01

 
 
 
 
61

Synthesis and characterization of terephthalate-intercalated NiAl layered double hydroxides with high Al content.  

Science.gov (United States)

Terephthalate-intercalated nickel-aluminum layered double hydroxides (LDHs) were prepared by a co-precipitation method, with nominal x values in the general formula Ni((1-x))Al(x)(OH)(2)(C(8)H(4)O(4))(x/2) in the range 0.3-0.8. The materials were characterized by X-ray diffraction, X-ray fluorescence spectroscopy, CHN analysis, thermogravimetric analysis, FTIR spectroscopy, EXAFS at the Ni edge and (27)Al NMR spectroscopy. A combination of XRD, XRF and CHN analysis indicated that crystalline LDHs with true x values up to 0.5 were obtained, along with increasing segregation of an aluminum hydroxide phase with increasing aluminum content. The EXAFS analysis indicated an upper limit of ca. 0.6 for the atomic fraction of aluminum at the second nickel coordination sphere. The (27)Al NMR analysis suggested that a phase containing octahedrally co-ordinated Al(3+) is segregated for nominal x values from 0.6 upwards. PMID:23188191

Arias, Santiago; Eon, Jean Guillaume; San Gil, Rosane A S; Licea, Yordy E; Palacio, Luz Amparo; Faro, Arnaldo C

2013-02-14

62

Dibutylphosphoric acid synthesis  

International Nuclear Information System (INIS)

[en] 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

1995-01-01

63

Adsorption and bonding of first layer and bilayer terephthalic acid on the Cu(100) surface by high-resolution electron energy loss spectroscopy.  

Science.gov (United States)

The self-assembled and highly ordered first layer of terephthalic acid on Cu(100) as well as its bilayer on the same surface are studied here using high-resolution electron energy loss spectroscopy (HREELS), Auger electron spectroscopy, and low energy electron diffraction. These experiments show completion of the first layer before growth of the second layer. HREELS measurements show that the first layer of the acid deprotonates, which is seen in the absence of the OH stretching mode for the acid groups. However, this mode is present in the bilayer structure, confirming that the deprotonation is due to a reaction with the Cu surface and suggesting that there is little mixing of the layers. It has been suggested previously that the TPA monolayer structure is stabilized by an intermolecular hydrogen bonding interaction, but we are not able to resolve any distortion of the CH stretching mode for such an interaction, but instead see evidence for direct bonding to the Cu surface. PMID:20550153

Ge, Yan; Adler, Hilmar; Theertham, Arjun; Kesmodel, Larry L; Tait, Steven L

2010-11-01

64

The effect of layer-by-layer chitosan-hyaluronic acid coating on graft-to-bone healing of a poly(ethylene terephthalate) artificial ligament.  

UK PubMed Central (United Kingdom)

Surface coating with an organic layer-by-layer self-assembled template of chitosan and hyaluronic acid on a poly(ethylene terephthalate) (PET) artificial ligament was designed for the promotion and enhancement of graft-to-bone healing after artificial ligament implantation in a bone tunnel. The results of in vitro culturing of MC3T3-E1 mouse osteoblastic cells supported the hypothesis that the layer-by-layer coating of chitosan and hyaluronic acid could promote the cell compatibility of grafts and could promote osteoblast proliferation. A rabbit extra-articular tendon-to-bone healing model was used to evaluate the effect of this kind of surface-modified stainless artificial ligament in vivo. The final results proved that this organic compound coating could significantly promote and enhance new bone formation at the graft-bone interface histologically and, correspondingly, the experimental group with coating had significantly higher biomechanical properties compared with controls at 8 weeks (P < 0.05).

Li H; Ge Y; Zhang P; Wu L; Chen S

2012-01-01

65

The effect of layer-by-layer chitosan-hyaluronic acid coating on graft-to-bone healing of a poly(ethylene terephthalate) artificial ligament.  

Science.gov (United States)

Surface coating with an organic layer-by-layer self-assembled template of chitosan and hyaluronic acid on a poly(ethylene terephthalate) (PET) artificial ligament was designed for the promotion and enhancement of graft-to-bone healing after artificial ligament implantation in a bone tunnel. The results of in vitro culturing of MC3T3-E1 mouse osteoblastic cells supported the hypothesis that the layer-by-layer coating of chitosan and hyaluronic acid could promote the cell compatibility of grafts and could promote osteoblast proliferation. A rabbit extra-articular tendon-to-bone healing model was used to evaluate the effect of this kind of surface-modified stainless artificial ligament in vivo. The final results proved that this organic compound coating could significantly promote and enhance new bone formation at the graft-bone interface histologically and, correspondingly, the experimental group with coating had significantly higher biomechanical properties compared with controls at 8 weeks (P < 0.05). PMID:21255485

Li, Hong; Ge, Yunsheng; Zhang, Pengyun; Wu, Lingxiang; Chen, Shiyi

2011-01-21

66

The chemoenzymatic synthesis of usnic acid.  

UK PubMed Central (United Kingdom)

Usnic acid, a highly functionalized dibenzofuran, is a polyketide secondary metabolite produced by several species of lichens. Synthesis of usnic acid from commercially available starting material was accomplished in two steps. The synthesis involves the methylation of phloracetophenone followed by oxidation with horseradish peroxidase. This work will lay the foundation for further biosynthetic studies on usnic acid.

Hawranik DJ; Anderson KS; Simmonds R; Sorensen JL

2009-05-01

67

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

68

Hydroxamic acids in asymmetric synthesis.  

UK PubMed Central (United Kingdom)

Metal-catalyzed stereoselective reactions are a central theme in organic chemistry research. In these reactions, the stereoselection is achieved predominantly by introducing chiral ligands at the metal catalyst's center. For decades, researchers have sought better chiral ligands for asymmetric catalysis and have made great progress. Nevertheless, to achieve optimal stereoselectivity and to catalyze new reactions, new chiral ligands are needed. Because of their high metal affinity, hydroxamic acids play major roles across a broad spectrum of fields from biochemistry to metal extraction. Dr. K. Barry Sharpless first revealed their potential as chiral ligands for asymmetric synthesis in 1977: He published the chiral vanadium-hydroxamic-acid-catalyzed, enantioselective epoxidation of allylic alcohols before his discovery of Sharpless asymmetric epoxidation, which uses the titanium-tartrate complex as the chiral reagent. However, researchers have reported few highly enantioselective reactions using metal-hydroxamic acid as catalysts since then. This Account summarizes our research on metal-catalyzed asymmetric epoxidation using hydroxamic acids as chiral ligands. We designed and synthesized a series of new hydroxamic acids, most notably the C2-symmetric bis-hydroxamic acid (BHA) family. V-BHA-catalyzed epoxidation of allylic and homoallylic alcohols achieved higher activity and stereoselectivity than Sharpless asymmetric epoxidation in many cases. Changing the metal species led to a series of unprecedented asymmetric epoxidation reactions, such as (i) single olefins and sulfides with Mo-BHA, (ii) homoallylic and bishomoallylic alcohols with Zr- and Hf-BHA, and (iii) N-alkenyl sulfonamides and N-sulfonyl imines with Hf-BHA. These reactions produce uniquely functionalized chiral epoxides with good yields and enantioselectivities.

Li Z; Yamamoto H

2013-02-01

69

Phosphatidic acid synthesis in bacteria.  

UK PubMed Central (United Kingdom)

Membrane phospholipid synthesis is a vital facet of bacterial physiology. Although the spectrum of phospholipid headgroup structures produced by bacteria is large, the key precursor to all of these molecules is phosphatidic acid (PtdOH). Glycerol-3-phosphate derived from the glycolysis via glycerol-phosphate synthase is the universal source for the glycerol backbone of PtdOH. There are two distinct families of enzymes responsible for the acylation of the 1-position of glycerol-3-phosphate. The PlsB acyltransferase was discovered in Escherichia coli, and homologs are present in many eukaryotes. This protein family primarily uses acyl-acyl carrier protein (ACP) endproducts of fatty acid synthesis as acyl donors, but may also use acyl-CoA derived from exogenous fatty acids. The second protein family, PlsY, is more widely distributed in bacteria and utilizes the unique acyl donor, acyl-phosphate, which is produced from acyl-ACP by the enzyme PlsX. The acylation of the 2-position is carried out by members of the PlsC protein family. All PlsCs use acyl-ACP as the acyl donor, although the PlsCs of the ?-proteobacteria also may use acyl-CoA. Phospholipid headgroups are precursors in the biosynthesis of other membrane-associated molecules and the diacylglycerol product of these reactions is converted to PtdOH by one of two distinct families of lipid kinases. The central importance of the de novo and recycling pathways to PtdOH in cell physiology suggest that these enzymes are suitable targets for the development of antibacterial therapeutics in Gram-positive pathogens. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.

Yao J; Rock CO

2013-03-01

70

Enantioselective total synthesis of (+)-lithospermic acid.  

Science.gov (United States)

An enantioselective synthesis of (+)-lithospermic acid, a potent anti-HIV agent, has been accomplished in a convergent manner in nine steps. The synthesis features an enantioselective intramolecular oxa-Michael addition catalyzed by a quinidine derivative, a hypervalent iodine-mediated rearrangement of chromanone to dihydrobenzofuran, an enantioselective ?-oxyamination, and an intermolecular C-H olefination. PMID:22978790

Ghosh, Arun K; Cheng, Xu; Zhou, Bing

2012-09-14

71

Enantioselective total synthesis of (+)-lithospermic acid.  

UK PubMed Central (United Kingdom)

An enantioselective synthesis of (+)-lithospermic acid, a potent anti-HIV agent, has been accomplished in a convergent manner in nine steps. The synthesis features an enantioselective intramolecular oxa-Michael addition catalyzed by a quinidine derivative, a hypervalent iodine-mediated rearrangement of chromanone to dihydrobenzofuran, an enantioselective ?-oxyamination, and an intermolecular C-H olefination.

Ghosh AK; Cheng X; Zhou B

2012-10-01

72

BIS- beta -HYDROXYETHYL TEREPHTHALATE  

UK PubMed Central (United Kingdom)

Bis- beta -hydroxyethyl terephthalate which has such a purity to provide an optical density of 0.000 to 0.006 at a wave length of 380 nm as measured under conditions wherein a cell optical path length is 10 mm and use is made of a methanol solution thereof having a concentration of 10 wt %. It has been found that a purified BHET having an optical density of 0.006 or less at a wave length of 380 nm can yield a high quality PET being excellent in purity, whiteness, transparency and the like.

INADA SHUJI; SATO KIKUCHI

73

Fatty Acid Synthesis by Extracts of Euglena.  

Science.gov (United States)

It is shown that stearic acid, a major produce of fatty acid synthesis by extracts of Euglena, is synthesized de novo. Moreover, avidin, an inhibitor of biotin-functional enzymes, does not inhibit the system from Euglena and does not alter the distributio...

G. M. Cheniae P. C. Kerr

1964-01-01

74

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

2008-01-01

75

Synthesis of pulcherriminic acid by Bacillus subtilis.  

UK PubMed Central (United Kingdom)

The pathway of pulcherriminic acid synthesis in Bacillus subtilis strains AM and AM-L11 (a leucine-requiring auxotroph) was investigated. Determinations of radioactivity in pulcherriminic acid synthesized by cells growing in media containing (14)C-labeled amino acids indicated that B. subtilis produced pulcherriminic acid from l-leucine. The organism utilized the carbon skeletons of two l-leucine molecules to synthesize one molecule of pulcherriminic acid. Similar results were obtained with starved cell suspensions. Growing cells formed significant amounts of pulcherriminic acid only in media including a carbohydrate such as starch. However, carbohydrate carbon was not required for the synthesis of pulcherriminic acid molecules. Data obtained with cell suspensions supported the hypothesis that cyclo-l-leucyl-l-leucyl is an intermediate in pulcherriminic acid biosynthesis and indicated that molecular oxygen is required for the conversion of cyclo-l-leucyl-l-leucyl to pulcherriminic acid. A pathway for the synthesis of pulcherrimin from l-leucine in B. subtilis is proposed.

Uffen RL; Canale-Parola E

1972-07-01

76

Synthesis of Pulcherriminic Acid by Bacillus subtilis  

Science.gov (United States)

The pathway of pulcherriminic acid synthesis in Bacillus subtilis strains AM and AM-L11 (a leucine-requiring auxotroph) was investigated. Determinations of radioactivity in pulcherriminic acid synthesized by cells growing in media containing 14C-labeled amino acids indicated that B. subtilis produced pulcherriminic acid from l-leucine. The organism utilized the carbon skeletons of two l-leucine molecules to synthesize one molecule of pulcherriminic acid. Similar results were obtained with starved cell suspensions. Growing cells formed significant amounts of pulcherriminic acid only in media including a carbohydrate such as starch. However, carbohydrate carbon was not required for the synthesis of pulcherriminic acid molecules. Data obtained with cell suspensions supported the hypothesis that cyclo-l-leucyl-l-leucyl is an intermediate in pulcherriminic acid biosynthesis and indicated that molecular oxygen is required for the conversion of cyclo-l-leucyl-l-leucyl to pulcherriminic acid. A pathway for the synthesis of pulcherrimin from l-leucine in B. subtilis is proposed.

Uffen, Robert L.; Canale-Parola, E.

1972-01-01

77

Alternaric acid: formal synthesis and related studies.  

UK PubMed Central (United Kingdom)

A silyl glyoxylate three-component-coupling methodology has been exploited to achieve a formal synthesis, an analogue to an intermediate in a distinct formal synthetic route, and a third (unique) approach to the natural product alternaric acid. Highlighted in this study is the versatility of silyl glyoxylates to engage a variety of nucleophile and electrophile pairs to provide wide latitude in the approach to complex molecule synthesis.

Slade MC; Johnson JS

2013-01-01

78

Synthesis of alpha-amino acids  

Energy Technology Data Exchange (ETDEWEB)

A method for synthesizing alpha amino acids proceding through novel intermediates of the formulas: R.sub.1 R.sub.2 C(OSOCl)CN, R.sub.1 R.sub.2 C(Cl)CN and [R.sub.1 R.sub.2 C(CN)O].sub.2 SO wherein R.sub.1 and R.sub.2 are each selected from hydrogen monovalent substituted and unsubstituted hydrocarbon radicals of 1 to 12 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the synthesis methods of the prior art.

Davis, Jr., Jefferson W. (San Francisco, CA)

1983-01-01

79

Synthesis of alpha-amino acids  

Energy Technology Data Exchange (ETDEWEB)

A method for synthesizing alpha amino acids proceeding through novel intermediates of the formulas: R.sub.1 R.sub.2 C(OSOCl)CN, R.sub.1 R.sub.2 C(Cl)CN and [R.sub.1 R.sub.2 C(CN)O].sub.2 SO wherein R.sub.1 and R.sub.2 are each selected from hydrogen monovalent substituted and unsubstituted hydrocarbon radicals of 1 to 12 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the synthesis methods of the prior art.

Davis, Jr., Jefferson W. (San Francisco, CA)

1983-01-01

80

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

This scientific opinion of EFSA deals with the safety evaluation of the oxygen absorber (terephthalic acid, dimethyl ester, polymer with 1,4-butanediol, cyclized, polymers with glycidyl methacrylate, hydroxyl-terminated polybutadiene, methyl methacrylate and styrene) copolymer (CAS No 12234...

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

 
 
 
 
81

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; Carlos E. S. Valério; Nara. R. de S. Basso; Fernando Guaragna; Sandra Einloft; Martine Tessier; Alain Fradet

2005-01-01

82

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

UK PubMed Central (United Kingdom)

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.

Li J; Gu JD

2006-05-01

83

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

84

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-03-10

85

Synthesis of alpha-amino acids  

Energy Technology Data Exchange (ETDEWEB)

A method for synthesizing alpha amino acids proceding through novel intermediates of the formulas: R.sub.1 R.sub.2 C(OSOCl)CN, R.sub.1 R.sub.2 C(Cl)CN and [R.sub.1 R.sub.2 C(CN)O].sub.2 SO wherein R.sub.1 and R.sub.2 are each selected from hydrogen monovalent substituted and unsubstituted hydrocarbon radicals of 1 to 10 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the snythesis methods of the prior art.

Davis, Jr., Jefferson W. (San Francisco, CA)

1983-01-01

86

Proton and deuterium NMR experiments in zero field. [Perdeuterated p-demethoxybenzene, perdeuterated malonic acid, diethyl terephthalate-d4, nonadecane-2,2'-D2, sodium propionate-D2  

Energy Technology Data Exchange (ETDEWEB)

High field solid-state NMR lineshapes suffer from inhomogeneous broadening since resonance frequencies are a function of molecular orientation. Time domain zero field NMR is a two-dimensional field-cycling technique which removes this broadening by probing the evolution of the spin system under zero applied field. The simplest version, the sudden transition experiment, induces zero field evolution by the sudden removal of the applied magnetic field. Theory and experimental results of this experiment and several variations using pulsed dc magnetic fuelds to initiate zero field evolution are presented. In particular, the pulsed indirect detection method allows detection of the zero field spectrum of one nuclear spin species via another (usually protons) by utilizing the level crossings which occur upon adiabatic demagnetization to zero field. Experimental examples of proton/deuteron systems are presented which demonstrate the method results in enhanced sensitivity relative to that obtained in sudden transition experiments performed directly on deuterium. High resolution /sup 2/H NQR spectra of a series of benzoic acid derivatives are obtained using the sudden transition and indirect detection methods. Librational oscillations in the water molecules of barium chlorate monohydrate are studied using proton and deuterium ZF experiments. 177 refs., 88 figs., 2 tabs.

Millar, J.M.

1986-02-01

87

A diastereoselective formal synthesis of berkelic acid.  

UK PubMed Central (United Kingdom)

A formal synthesis of berkelic acid is reported. The strategy employs the combination of a chiral exocyclic enol ether and an achiral isochromanone to afford the chroman spiroketal core via a base-triggered generation and cycloaddition of an o-quinone methide intermediate. Other key steps include equilibration of the spiroketal, intramolecular benzylic oxidation, and lactone addition/hemiketal reduction; all occur with good diastereoselectivity.

Wenderski TA; Marsini MA; Pettus TR

2011-01-01

88

A diastereoselective formal synthesis of berkelic acid.  

Science.gov (United States)

A formal synthesis of berkelic acid is reported. The strategy employs the combination of a chiral exocyclic enol ether and an achiral isochromanone to afford the chroman spiroketal core via a base-triggered generation and cycloaddition of an o-quinone methide intermediate. Other key steps include equilibration of the spiroketal, intramolecular benzylic oxidation, and lactone addition/hemiketal reduction; all occur with good diastereoselectivity. PMID:21138313

Wenderski, Todd A; Marsini, Maurice A; Pettus, Thomas R R

2010-12-07

89

para-Benzene disulfonic acid and its tetrachloro and tetrafluoro derivatives--studies towards polyhalogenated metal-organic-frameworks with sulfo analogues of terephthalic acid.  

UK PubMed Central (United Kingdom)

We developed convenient synthetic routes for the preparation of para-benzene disulfonic acid (H(2)BDS) and its tetrachloro (H(2)BDSCl(4)) and tetrafluoro (H(2)BDSF(4)) derivatives. The reaction of these acids with zinc nitrate in DMF led to single crystals of [Zn(BDS)(DMF)(2)] (triclinic, P ?1[combining macron], Z=2, a=976.62(4), b=986.85(4), c=1014.40(4), ?=69.106(2)°, ?=68.746(2)°, ?=86.295(2)°, wR(2)=0.0627), [Zn(BDSCl(4))(DMF)(4)] (triclinic, P ?1[combining macron], Z=1, a=831.5(1), b=905.2(1), c=989.6(1), ?=90.44(2)°, ?=91.41 (2)°, ?=106.72(2)°, wR(2)=0.0635), and [Zn(BDSF(4))(DMF)(4)] (monoclinic, P2(1)/c, Z=2, a=889.01(3), b=968.91(3), c=1633.07(5) pm, ?=106.524(2)°, wR(2)=0.0948). While [Zn(BDS)(DMF)(2)] exhibits a layer structure, the disulfonate linkers connect the zinc ions into chains in the crystal structures of [Zn(BDSCl(4))(DMF)(4)] and [Zn(BDSF(4))(DMF)(4)]. Thermoanalytical investigations revealed that desolvation of the compounds occurs in a temperature range between 100 and 200 °C. The solvent free sulfonates show remarkably high stabilities, [Zn(BDS)(DMF)(2)] is stable up to nearly 600 °C. The halogenated acids were also used to prepare copper salts from aqueous solutions and Cu(2)(OH)(2)(CO(3)) (malachite) as a copper source. The crystal structure of [Cu(H(2)O)(6)](BDSF(4)) (triclinic, P ?1[combining macron], Z=1, a=510.45(2), b=744.68(3), c=1077.77(4) pm, ?=85.627 (2)°, ?=77.449 (2)°, ?=76.015 (2)°) exhibits complex cations and uncoordinated sulfonate anions, while in [Cu(BDSCl(4))(H(2)O)(4)] (orthorhombic, Pnma, Z=4, a=721.27(2), b=2147.81(6), c=979.42(3) pm) the Cu(2+) ions are linked to infinite chains in the crystal structure. The most interesting structural feature of [Cu(BDSCl(4))(H(2)O)(4)] is the significant deviation from planarity of the disulfonate dianion. Theoretical investigations revealed that a boat conformation is favoured due to steric hindrance in cases where a syn coordination of the sulfonate groups occurs. The thermal behaviour of the copper compounds was also investigated by DTA/TG measurements and X-ray powder diffraction.

Muesmann TW; Zitzer C; Mietrach A; Klüner T; Christoffers J; Wickleder MS

2011-04-01

90

Transaminases for the synthesis of enantiopure beta-amino acids  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optically pure ?-amino acids constitute interesting building blocks for peptidomimetics and a great variety of pharmaceutically important compounds. Their efficient synthesis still poses a major challenge. Transaminases (also known as aminotransferases) possess a great potential for the synthesis of...

Rudat, Jens; Brucher, Birgit R; Syldatk, Christoph

91

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 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 na indústria de reciclagem deve-se à sua ampla diversidade de aplicações, desde a indústria têxtil (multifilamento) até as indústrias de alimentos, onde as embal (more) agens 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 repro (more) cessing 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.

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

2009-06-01

92

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

Directory of Open Access Journals (Sweden)

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

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

2009-01-01

93

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

Science.gov (United States)

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

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

2012-08-01

94

BIS-BETA-HYDROXYETHYL TEREPHTHALATE  

UK PubMed Central (United Kingdom)

Bis- beta -hydroxyethyl terephthalate having an optical density measured in a 10 wt% methanol solution at a measurement wavelength of 380 nm and a cell optical path length of 10 mm of 0.000 to 0.006. The present invention makes it clear that purified BHET having an optical density of 0.006 or less provides high-quality PET having excellent purity, whiteness and transparency.

INADA SHUJI; SATO KIKUCHI

95

Hyaluronic acid lipoate: synthesis and physicochemical properties.  

UK PubMed Central (United Kingdom)

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

Picotti F; Fabbian M; Gianni R; Sechi A; Stucchi L; Bosco M

2013-03-01

96

Protein synthesis in the presence of carbamoyl-amino acids  

Energy Technology Data Exchange (ETDEWEB)

The role of exogenous carbamoyl-amino acids in protein biosynthesis has been examined in vitro using a mixture of UC amino acids to label newly synthesized protein in human reticulocyte rich (8-18%) peripheral blood. Aliquots of the radiolabeled newly synthesized protein were acid precipitated, washed and the radioactivity measured. Control samples which measured the synthetic capacity of the blood were aliquots of the same blood- UC amino acid mixture without added carbamoyl-amino acids or cyanate. N-carbamoyl leucine alone or a 3 N-carbamoyl amino acid mixture of leucine, aspartic acid and tyrosine were used to test inhibition of protein synthesis. Also carbamoyl-amino acids were synthesized using cyanate and Pierce hydrolyzate amino acid calibration standards or the mixture of UC amino acids. In this system the carbamoylation of endogenous amino acids by cyanate up to 8 mol/100 l showed a linear decrease in protein synthesis with time which is inversely related to the cyanate concentration. At greater cyanate levels the inhibition of protein synthesis reaches a plateau. When N-carbamoyl-amino acids only are present there is about a 50% decrease in the UC protein at 30 minutes as compared to the synthesis of UC protein without N-carbamoyl-amino acids. These results indicate that the presence of carbamoyl-amino acids interferes with protein synthesis.

Kraus, L.M.; Stephens, M.C.

1987-05-01

97

Organocatalytic asymmetric synthesis of ?(3)-amino acid derivatives.  

UK PubMed Central (United Kingdom)

?(3)-Amino acid derivatives are an essential resource for pharmaceutical production, medicinal chemistry, and biochemistry. In this article, recent developments in versatile organocatalysis, i.e., Brønsted acid catalysis, Brønsted base catalysis, Lewis acid catalysis, Lewis base catalysis, and phase-transfer catalysis, for the asymmetric synthesis of ?(3)-amino acid derivatives will be presented.

Kim SM; Yang JW

2013-08-01

98

Profiles in garbage: Polyethylene terephthalate  

Energy Technology Data Exchange (ETDEWEB)

Polyethylene terephthalate (PET) is a plastic resin used primarily to make bottles. Soft drinks -- along with salad dressing, fruit juices, peanut butter, and other household and consumer products -- use PET bottles. PET also is used for film, sheeting for cups and food trays, oven-safe trays, and other uses. PET is a relatively new packaging resin, first commercialized in the early 1970s. Because it is an ``engineered`` resin, PET is more expensive than commodity resins such as high-density polyethylene (HDPE) and, for the same reason, it is usually the highest valued plastic recyclable.

Miller, C. [Environmental Industry Associations, Washington, DC (United States)

1997-11-01

99

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

2013-07-26

100

Synthesis Modulation as a Tool To Increase the Catalytic Activity of Metal-Organic Frameworks: The Unique Case of UiO-66(Zr).  

UK PubMed Central (United Kingdom)

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.

Vermoortele F; Bueken B; Le Bars G; Van de Voorde B; Vandichel M; Houthoofd K; Vimont A; Daturi M; Waroquier M; Van Speybroeck V; Kirschhock C; De Vos DE

2013-08-01

 
 
 
 
101

Synthesis and conductivity of undecatungstozircogallic heteropoly acid  

International Nuclear Information System (INIS)

[en] The undecatungstozircogallic heteropoly acid (HPA) H5[Ga(H2O)ZrW11O39].14H2O was synthesized for the first time by the stepwise acidification and the stepwise addition of solution of the component elements. The optimal proportion of the component compounds and the pH of the synthesis reaction are given. The product was characterized by means of inductively coupled plasma (ICP), IR, UV, X-ray diffraction and thermal analysis. The results of AC impedance measurement show that its proton conductivity is 8.76x10-4 S cm-1 at room temperature (16 deg. C) and the activation energy for proton conduction is 21.20 kJ mol-1

2003-11-15

102

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 e...

Zlatanos, S.; Laskaridis, K.; Koliokota, E.; Sagredos, A.

103

Polymeric cracking of waste polyethylene terephthalate to chemicals and energy.  

UK PubMed Central (United Kingdom)

Polyethylene terephthalate (PET) is a widely used thermoplastic. PET residues represent on average 7.6 wt% of the different polymer wastes in Europe. Pyrolysis of these wastes is attracting increasing interest, and PET is a potential candidate for this thermal process. The paper measures and discusses the kinetics of the pyrolysis reaction in terms of the reaction rate constants as determined by dynamic thermogravimetric analysis, with special emphasis on the required heating rate to obtain relevant results. The product yields and compositions are also determined. Gaseous products represent 16-18 wt%. The amounts of condensables and carbonaceous residue are a function of the operating mode, with slow pyrolysis producing up to 24 wt% of carbonaceous residue. Major condensable components are benzoic acid, monovinyl terephthalate, divinyl terephthalate, vinyl benzoate, and benzene. The present paper complements previous literature findings by (1) the study of the influence of the heating rate on the reaction kinetics in dynamic pyrolysis tests, (2) the isothermal investigation in a fluidized bed reactor to pyrolyze PET, and (3) the assessment of upgrading and recovery of the products. The paper concludes with a proposed reactor recommendation for PET pyrolysis, in either the bubbling or circulating fluidized bed operating mode.

Brems A; Baeyens J; Vandecasteele C; Dewil R

2011-07-01

104

Aldol reactions of dioxanes derived from tartaric acid. A total synthesis of (+)-nephrosteranic acid.  

UK PubMed Central (United Kingdom)

[reaction: see text]. A general enantioselective synthesis of the paraconic acids was developed. The key step was a highly stereoselective aldol reaction between a dioxane dithioester derived from l-tartaric acid and a suitable aldehyde.

Barros MT; Maycock CD; Ventura MR

2003-10-01

105

Aldol reactions of dioxanes derived from tartaric acid. A total synthesis of (+)-nephrosteranic acid.  

Science.gov (United States)

[reaction: see text]. A general enantioselective synthesis of the paraconic acids was developed. The key step was a highly stereoselective aldol reaction between a dioxane dithioester derived from l-tartaric acid and a suitable aldehyde. PMID:14572258

Barros, M Teresa; Maycock, Christopher D; Ventura, M Rita

2003-10-30

106

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

Directory of Open Access Journals (Sweden)

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

107

Synthesis of camptothecin-amino acid carbamate linkers.  

Science.gov (United States)

A more convenient and facile approach for the synthesis and production of camptothecin-amino acids carbamate linkers, that can be used in the synthesis of bioconjugate peptides JF-10-81, JF-10-71, and other peptide analogs designed to target somatostatin receptors has been described. PMID:21431932

Etienne, Marcus A; Kostochka, Mikhail; Fuselier, Joseph A; Coy, David H

2011-03-24

108

Synthesis of camptothecin-amino acid carbamate linkers.  

UK PubMed Central (United Kingdom)

A more convenient and facile approach for the synthesis and production of camptothecin-amino acids carbamate linkers, that can be used in the synthesis of bioconjugate peptides JF-10-81, JF-10-71, and other peptide analogs designed to target somatostatin receptors has been described.

Etienne MA; Kostochka M; Fuselier JA; Coy DH

2012-05-01

109

Synthesis, crystal structures, and luminescence properties of carboxylate based rare-earth coordination polymers.  

Science.gov (United States)

Rare-earth coordination polymers or lanthanide-organic frameworks with hitherto unreported crystal structures have been obtained on the basis of the "light" lanthanides Pr, Nd, Sm, and Eu in combination with terephthalic acid and using a slightly altered literature synthesis procedure. Rietveld refinement has shown that powder XRD patterns of such compounds are largely dominated by the positions of the heavy elements, pointing to isostructural networks for all four terephthalate-based materials. An in-depth luminescence study has been performed on the reported MOFs, showing rare praseodymium and samarium emission in the visible spectrum, aside from the strong europium luminescence and the near-infrared emission from both a terephthalate and 2,5-pyridinedicarboxylate based neodymium-MOF. PMID:23078525

Decadt, Roel; Van Hecke, Kristof; Depla, Diederik; Leus, Karen; Weinberger, David; Van Driessche, Isabel; Van Der Voort, Pascal; Van Deun, Rik

2012-10-18

110

Synthesis, crystal structures, and luminescence properties of carboxylate based rare-earth coordination polymers.  

UK PubMed Central (United Kingdom)

Rare-earth coordination polymers or lanthanide-organic frameworks with hitherto unreported crystal structures have been obtained on the basis of the "light" lanthanides Pr, Nd, Sm, and Eu in combination with terephthalic acid and using a slightly altered literature synthesis procedure. Rietveld refinement has shown that powder XRD patterns of such compounds are largely dominated by the positions of the heavy elements, pointing to isostructural networks for all four terephthalate-based materials. An in-depth luminescence study has been performed on the reported MOFs, showing rare praseodymium and samarium emission in the visible spectrum, aside from the strong europium luminescence and the near-infrared emission from both a terephthalate and 2,5-pyridinedicarboxylate based neodymium-MOF.

Decadt R; Van Hecke K; Depla D; Leus K; Weinberger D; Van Driessche I; Van Der Voort P; Van Deun R

2012-11-01

111

Synthesis of new C?-tetrasubstituted ?-amino acids  

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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?-tetrasubstitu...

Andreas A. Grauer; Burkhard König

112

A Diels-Alder-based total synthesis of (-)-kainic acid.  

UK PubMed Central (United Kingdom)

An efficient synthesis of (-)-kainic acid, through a high-pressure-promoted Diels-Alder cycloaddition of a vinylogous malonate derived from 4-hydroxyproline, is described. The bicyclic adduct could be converted into the natural product with complete stereocontrol.

Orellana A; Pandey SK; Carret S; Greene AE; Poisson JF

2012-06-01

113

Trials of separation of the rare-earth elements on the way of fractional precipitation of terephthalates  

Energy Technology Data Exchange (ETDEWEB)

A possibility of the rare-earth elements separation on the way of fractional precipitation of terephthalates in the presence of a complexing agent was studied. Selecting an appropriate quantity of the complexing agent, it is possible to obtain fractions differing in their composition. In the first fractions the light lanthanides accumulate, whereas in the last one accumulate Y and heavy lanthanides. The advantage of this method is that the terephthalic acid can be regenerated practically in 100%.

Brzyska, W. (Uniwersytet Marii Curie-Sklodowskiej, Lublin (Poland))

1980-01-01

114

Waste product profile: Polyethylene terephthalate  

Energy Technology Data Exchange (ETDEWEB)

Polyethylene terephthalate (PET) is a plastic resin used primarily to make bottles. Soft drinks are the primary product packaged in PET. Salad dressing, peanut butter, and other household and consumer products also use PET bottles. PET is also used for film, sheeting for cups and food trays, ovenable trays, and other uses. PET is a relatively new packaging resin, first commercialized in the early `70s. Because it is an ``engineered`` resin, it is more expensive than commodity resins such as high-density polyethylene (HDPE). The primary market for recycled PET is the fiber industry, which uses PET for carpet fiber, sweaters and other clothing, and for other uses. Recycled PET can also be used for food and beverage containers. Export markets, particularly Asian countries, are becoming increasingly important.

Miller, C. [Environmental Industry Associations, Washington, DC (United States)

1996-02-01

115

Prebiotic Amino Acid Thioester Synthesis: Thiol-Dependent Amino Acid Synthesis from Formose Substrates (Formaldehyde and Glycolaldehyde) and Ammonia  

Science.gov (United States)

Formaldehyde and glycolaldehyde (substrates of the formose autocatalytic cycle) were shown to react with ammonia yielding alanine and homoserine under mild aqueous conditions in the presence of thiol catalysts. Since similar reactions carried out without ammonia yielded ?-hydroxy acid thioesters (Weber, 1984a, b), the thiol-dependent synthesis of alanine and homoserine is presumed to occur via amino acid thioesters - intermediates capable of forming peptides (Weber and Orgel 1979). A pH 5.2 solution of 20 mM formaldehyde, 20 mM glycolaldehyde, 20 mM ammonium chloride, 23 mM 3-mercaptopropionic acid, and 23 mM acetic acid that reacted for 35 days at 40°C yielded (based on initial formaldehyde) 1.8% alanine and 0.08% homoserine. In the absence of thiol catalyst, the synthesis of alanine and homoserine was negligible. Alanine synthesis required both formaldehyde and glycolaldehyde, but homoserine synthesis required only glycolaldehyde. At 25 days the efficiency of alanine synthesis calculated from the ratio of alanine synthesized to formaldehyde reacted was 2.1%, and the yield (based on initial formaldehyde) of triose and tetrose intermediates involved in alanine and homoserine synthesis was 0.3 and 2.1%, respectively. Alanine synthesis was also seen in similar reactions containing only 10 mM each of aldehyde substrates, ammonia, and thiol. The prebiotic significance of these reactions that use the formose reaction to generate sugar intermediates that are converted to reactive amino acid thioesters is discussed.

Weber, Arthur L.

1998-06-01

116

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

Directory of Open Access Journals (Sweden)

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

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

2005-01-01

117

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

Science.gov (United States)

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

2006-05-05

118

A convenient stereoselective synthesis of trifluoromethyl-substituted polyfunctionalized cyclopropane: synthesis of (+/-)-trans-trifluoronorcoronamic acid.  

Science.gov (United States)

Trifluoromethylated polyfunctionalized cyclopropanes were obtained in high stereoselectivity by reacting 2-bromo-3,3,3-trifluoropropene (BrTFP) with active methylenes. This novel method was further applied to the synthesis of (+/-)-trans-trifluoronorcoronamic acid. PMID:12638987

Jiang, Biao; Zhang, Fangjiang; Xiong, Wennan

2003-02-21

119

A convenient stereoselective synthesis of trifluoromethyl-substituted polyfunctionalized cyclopropane: synthesis of (+/-)-trans-trifluoronorcoronamic acid.  

UK PubMed Central (United Kingdom)

Trifluoromethylated polyfunctionalized cyclopropanes were obtained in high stereoselectivity by reacting 2-bromo-3,3,3-trifluoropropene (BrTFP) with active methylenes. This novel method was further applied to the synthesis of (+/-)-trans-trifluoronorcoronamic acid.

Jiang B; Zhang F; Xiong W

2003-02-01

120

?-Unsaturated ?-amino acids: enantiodivergent synthesis and cell imaging studies.  

UK PubMed Central (United Kingdom)

Synthesis of both enantiomers of ?-unsaturated ?-amino acids via the enantiodivergent [3,3]-sigmatropic rearrangement strategy is reported. Excellent enantiomeric excess > 94% are observed in the strategy. Cell permeability of a fluorescent amino acid derivative is evaluated by live-cell imaging.

Kand D; Chauhan DP; Lahiri M; Talukdar P

2013-05-01

 
 
 
 
121

Stereoselective Synthesis of Sialylated Tumor-Associated Glycosylamino Acids.  

UK PubMed Central (United Kingdom)

Suitably protected sialyl TN and 2,6-sialyl T tumor-associated carbohydrate antigen-derived amino acids have been prepared stereoselectively using an oxazolidinone-derived sialoside donor. These glycosylamino acids can be employed directly in the solid-phase synthesis of glycopeptides, as demonstrated by the efficient preparation of tumor-associated MUC1 glycopeptide fragments.

Corcilius L; Payne RJ

2013-10-01

122

Ferrocene-containing nucleic acids. Synthesis and electrochemical properties  

Energy Technology Data Exchange (ETDEWEB)

The published data on the synthesis of ferrocene-containing nucleic acid fragments are generalised. The known methods are systematised and their advantages and disadvantages are discussed. The use of nucleoside, nucleotide and oligonucleotide conjugates with ferrocene in the design of systems for electrochemical detection of nucleic acids is considered.

Zatsepin, Timofei S; Andreev, Sergei Yu; Oretskaya, Tat' yana S [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Hianik, T [Comenius University (Slovakia)

2003-06-30

123

Microwave-Promoted synthesis of novel N-Arylanthranilic acids  

International Nuclear Information System (INIS)

[en] 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)

2008-01-01

124

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

Science.gov (United States)

...COMMISSION [Investigation No. 731-TA-459 (Third Review)] Polyethylene Terephthalate (Pet) Film From Korea AGENCY: United States...five-year review concerning the antidumping duty order on polyethylene terephthalate (PET) film from...

2011-02-15

125

Recent synthesis of aminophosphonic acids as potential biological importance.  

UK PubMed Central (United Kingdom)

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

Naydenova ED; Todorov PT; Troev KD

2010-01-01

126

Recent synthesis of aminophosphonic acids as potential biological importance.  

Science.gov (United States)

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

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

2009-02-20

127

Asymmetric synthesis of carbon-14 labeled alpha amino acids  

International Nuclear Information System (INIS)

Adaptation of existing methodology for the asymmetric synthesis of unlabeled amino acids led to preparations of L-phenylalanine-2-14C and L-tyrosine-(ring-3,4-14C2), each having high radiochemical and enantiomeric purity. Reaction of the diketopiperazine derived from L-valine and glycine with an appropriate aldehyde provides a 2,3-dehydroamino acid precursor which undergoes asymmetric hydrogenation. Acid hydrolysis provides the new L-amino acid and L-valine (or whichever chiral amino acid was used to prepare the diketopiperazine and to induce asymmetric reduction) and these are readily separated. This approach can be applied to the synthesis of any carbon-labeled chiral alpha amino acid using labeled achiral starting materials. (author). 4 refs

1989-01-01

128

Influence of asiatic acid, madecassic acid, and asiaticoside on human collagen I synthesis.  

Science.gov (United States)

Asiatic acid, madecassic acid, and asiaticoside, terpenoids with an ursane skeleton, were tested separately and in combination on skin human fibroblast collagen I synthesis in vitro. In the absence of ascorbic acid, the mixture as well as each individual component stimulated collagen I synthesis to a similar extent. In the presence of ascorbic acid, the level of collagen I secretion was higher for each individual component and for the mixture. A comparison of asiaticoside and asiatic acid shows that the sugar moiety of the molecule does not seem to be necessary for this biological activity. PMID:8202564

Bonte, F; Dumas, M; Chaudagne, C; Meybeck, A

1994-04-01

129

Influence of asiatic acid, madecassic acid, and asiaticoside on human collagen I synthesis.  

UK PubMed Central (United Kingdom)

Asiatic acid, madecassic acid, and asiaticoside, terpenoids with an ursane skeleton, were tested separately and in combination on skin human fibroblast collagen I synthesis in vitro. In the absence of ascorbic acid, the mixture as well as each individual component stimulated collagen I synthesis to a similar extent. In the presence of ascorbic acid, the level of collagen I secretion was higher for each individual component and for the mixture. A comparison of asiaticoside and asiatic acid shows that the sugar moiety of the molecule does not seem to be necessary for this biological activity.

Bonte F; Dumas M; Chaudagne C; Meybeck A

1994-04-01

130

Synthesis of beta-difluorine-containing amino acids.  

Science.gov (United States)

A convenient strategy was developed to prepare several beta-difluoroamino acids. As exemplified by the synthesis of 3,3-difluoro-L-homocysteine, 3,3-difluoro-L-homoserine and 3,3-difluoro-L-methionine, the reaction sequence all started from L-isoascorbic acid. This approach holds potential to be extended to make other beta-difluorine-containing amino acids. PMID:9871715

Li, K; Leriche, C; Liu, H

1998-05-01

131

Synthesis of beta-difluorine-containing amino acids.  

UK PubMed Central (United Kingdom)

A convenient strategy was developed to prepare several beta-difluoroamino acids. As exemplified by the synthesis of 3,3-difluoro-L-homocysteine, 3,3-difluoro-L-homoserine and 3,3-difluoro-L-methionine, the reaction sequence all started from L-isoascorbic acid. This approach holds potential to be extended to make other beta-difluorine-containing amino acids.

Li K; Leriche C; Liu H

1998-05-01

132

Synthesis of [1-14C] palmitic acid  

International Nuclear Information System (INIS)

The synthesis of [1-14C] palmitic acid via Grignard Reaction is reported. The carbon-C14 dioxide was liberated by dropping sulfuric acid onto barium carbonate-C14. The yield of [1-14C] palmitic acid was 44.8%. A radiochemical purity of more than 99.5% was determined by HPLC and the product was proved to be free of impurity by TLC.

1997-01-01

133

Mechanism of Action of Nalidixic Acid on Escherichia coli II. Inhibition of Deoxyribonucleic Acid Synthesis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Goss, William A. (Sterling-Winthrop Research Institute, Rensselaer, N.Y.), William H. Deitz, and Thomas M. Cook. Mechanism of action of nalidixic acid on Escherichia coli. II. Inhibition of deoxyribonucleic acid synthesis. J. Bacteriol. 89:1068–1074. 1965.—Nalidixic acid was shown to inhibit specifi...

Goss, William A.; Deitz, William H.; Cook, Thomas M.

134

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1988-09-01

135

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

International Nuclear Information System (INIS)

[en] 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

1988-01-01

136

Fatty Acid Synthesis by Indonesian Marine Diatom, Chaetoceros gracilis  

Directory of Open Access Journals (Sweden)

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; DAHRUL SYAH; LINAWATI HARDJITO; LILY MARIA GORETTI PANGGABEAN; MAGGY THENAWIDJAJA SUHARTONO

2009-01-01

137

Synthesis of fluorinated cyclopropyl amino acid analogues: toward the synthesis of original fluorinated peptidomimetics.  

Science.gov (United States)

A straightforward, easy, and practical access to various amino acid analogues (methionine, leucine, lysine, and arginine) from a unique fluorinated cyclopropane scaffold is described. Moreover, the synthesis, for the first time, of one tripeptide incorporating a fluorinated cyclopropane amino acid (FCAA) analogue is reported. PMID:23227990

Milanole, Gaëlle; Couve-Bonnaire, Samuel; Bonfanti, Jean-François; Jubault, Philippe; Pannecoucke, Xavier

2012-12-17

138

Synthesis of fluorinated cyclopropyl amino acid analogues: toward the synthesis of original fluorinated peptidomimetics.  

UK PubMed Central (United Kingdom)

A straightforward, easy, and practical access to various amino acid analogues (methionine, leucine, lysine, and arginine) from a unique fluorinated cyclopropane scaffold is described. Moreover, the synthesis, for the first time, of one tripeptide incorporating a fluorinated cyclopropane amino acid (FCAA) analogue is reported.

Milanole G; Couve-Bonnaire S; Bonfanti JF; Jubault P; Pannecoucke X

2013-01-01

139

Different feedback regulation of hepatic cholesterol and bile acid synthesis by glycodeoxycholic acid in rabbits.  

UK PubMed Central (United Kingdom)

BACKGROUND: To explore the sexual difference in the feedback regulation of hepatic bile acid synthesis, glycodeoxycholic acid (GDCA) was administered to 15 male and 14 female rabbits. METHODS: After bile diversion, GDCA equivalent to the hepatic bile acid influx was infused intraduodenally. Biliary cholic acid output represented bile acid synthesis. Hepatic 3-hydroxy-3 methylglutaryl coenzyme A (HMG-CoA) reductase and cholesterol 7 alpha-hydroxylase activities and steady state messenger RNA (mRNA) levels were determined. RESULTS: GDCA inhibited bile acid synthesis less in female than in male rabbits. Hepatic HMG-CoA reductase activity decreased 39% in males, but increased 48% in females. Hepatic cholesterol 7 alpha-hydroxylase activity decreased similarly in males and females, and mRNA levels decreased 86% in males but were unchanged in females. CONCLUSIONS: (1) Total bile diversion stimulated both hepatic cholesterol and bile acid synthesis by activating the rate-controlling enzymes and increasing mRNA levels. (2) GDCA decreased mRNA levels of HMG-CoA reductase and cholesterol 7 alpha-hydroxylase in males, but mRNA levels did not decrease in females. (3) Bile acid synthesis was sustained in females because continued biosynthesis of cholesterol provided a substrate for cholesterol 7 alpha-hydroxylase and stimulus for enzyme formation.

Xu G; Salen G; Shefer S; Batta AK; Ness GC; Nguyen LB; Zhao Z; Chen TS; Niemann W; Tint GS

1993-10-01

140

Biobased synthesis of acrylonitrile from glutamic acid  

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Glutamic acid was transformed into acrylonitrile in a two step procedure involving an oxidative decarboxylation in water to 3-cyanopropanoic acid followed by a decarbonylation-elimination reaction using a palladium catalyst

Le Notre, J.E.L.; Scott, E.L.; Franssen, M.C.R.; Sanders, J.P.M.

 
 
 
 
141

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

Directory of Open Access Journals (Sweden)

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

Santosh Kumar Singh; Narendra Manne; Purna Chandra Ray; Manojit Pal

2008-01-01

142

Acetylsalicylic acid: Incoming 150 years of the first synthesis  

Directory of Open Access Journals (Sweden)

Full Text Available Acetylsalicylic acid is one of the most fascinating and versatile drugs known to medicine, as well as one of the oldest. Acetylsalicylic acid is a drug which is safe, with analgetic, antirheumatic, anti-inflammatory antiplatelet and antithrombotic action. It may be applied not only in clinical practice, but also as prevention. The first known use of an acetylsalicylic acid-like preparation can be traced to ancient Greece. In 1853 Charles Gerhardt published the first synthesis of acetylsalicylic acid. Felix Hoffmann, a chemist for Friedrich Bayer, a German dye company obtained a patent on acetylsalicylic acid some 40 years later. Bayer coined the name Aspirin for the new product. The 20 in century was the century in which many researchers in many companies tried to improve the synthesis of acetylsalicylic acid not only in terms of yield but also purity. This paper describes the history, use, mechanism of action, synthesis and production as well as the purification and stability of acetylsalicylic acid.

Mijin Dušan Ž.; Stankovi? Milena; Petrovi? Slobodan D.; Blagojevi? Milorad

2002-01-01

143

The Strecker synthesis as a source of amino acids in carbonaceous chondrites: deuterium retention during synthesis.  

UK PubMed Central (United Kingdom)

Deuterium-enriched amino acids occur in the Murchison carbonaceous chondrite. Synthesis from D-enriched interstellar precursors by Strecker reactions during aqueous alteration of the parent body has been proposed. To test this hypothesis, we have measured the retention of deuterium in amino acids produced from HCN, NH3, and formaldehyde-D2, acetaldehyde-D4, and acetone-D6 in H2O. The isotopic label is 50% to 98% retained, with variations in retentivity depending on the amino acid and the reaction conditions. If amino acids, once formed on the parent body by the Strecker synthesis, lose no deuterium by subsequent exchange with water or H-bearing minerals, then the observed deuterium isotopic composition of Murchison amino acids represents as much as 50% or more of the enrichments inherited from their interstellar precursors. Imino diacids are prominent side products of the Strecker synthesis which have not been reported in carbonaceous chondrites. Under the conditions of the Strecker reaction using deuterium labeled aldehydes and ketones, unlabeled amino acids are also formed by an HCN polymerization route indicating multiple pathways for the synthesis of amino acids in meteorites.

Lerner NR; Peterson E; Chang S

1993-10-01

144

The Strecker synthesis as a source of amino acids in carbonaceous chondrites: deuterium retention during synthesis.  

Science.gov (United States)

Deuterium-enriched amino acids occur in the Murchison carbonaceous chondrite. Synthesis from D-enriched interstellar precursors by Strecker reactions during aqueous alteration of the parent body has been proposed. To test this hypothesis, we have measured the retention of deuterium in amino acids produced from HCN, NH3, and formaldehyde-D2, acetaldehyde-D4, and acetone-D6 in H2O. The isotopic label is 50% to 98% retained, with variations in retentivity depending on the amino acid and the reaction conditions. If amino acids, once formed on the parent body by the Strecker synthesis, lose no deuterium by subsequent exchange with water or H-bearing minerals, then the observed deuterium isotopic composition of Murchison amino acids represents as much as 50% or more of the enrichments inherited from their interstellar precursors. Imino diacids are prominent side products of the Strecker synthesis which have not been reported in carbonaceous chondrites. Under the conditions of the Strecker reaction using deuterium labeled aldehydes and ketones, unlabeled amino acids are also formed by an HCN polymerization route indicating multiple pathways for the synthesis of amino acids in meteorites. PMID:11539581

Lerner, N R; Peterson, E; Chang, S

1993-10-01

145

Synthesis and antituberculosis activity of new fatty acid amides.  

UK PubMed Central (United Kingdom)

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.

D'Oca Cda R; Coelho T; Marinho TG; Hack CR; Duarte Rda C; da Silva PA; D'Oca MG

2010-09-01

146

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

2010-07-07

147

Automatic synthesis apparatus for 11C-fatty acids  

International Nuclear Information System (INIS)

Such short-lived nuclides as 11C, 13N and 15O for nuclear-medicine diagnosis are produced with the in-house cyclotrons in hospitals. After the production, their compounds are synthesized, and used for diagnosis immediately. Of these nuclides, 11C with relatively long half-life is the most useful. In the synthesis of its compounds, first the rapid procedure is required. Then, the start from large quantity of radioactivity is frequently carried out to secure the activity sufficient for the imaging of organs. Therefore, the synthesis must be conducted by remote operation for the radiation protection of personnel. The development of an automatic synthesis apparatus for labeled-compounds is made along this line. Taking up the case of 11C-fatty acids, the following matters are described: synthetic reactions, the synthesis of 11C-fatty acids, an automatic synthesis apparatus for 11C-fatty acid made for trial, and applications. (J.P.N.)

1981-01-01

148

Automatic synthesis apparatus for /sup 11/C-fatty acids  

Energy Technology Data Exchange (ETDEWEB)

Such short-lived nuclides as /sup 11/C, /sup 13/N and /sup 15/O for nuclear-medicine diagnosis are produced with the in-house cyclotrons in hospitals. After the production, their compounds are synthesized, and used for diagnosis immediately. Of these nuclides, /sup 11/C with relatively long half-life is the most useful. In the synthesis of its compounds, first the rapid procedure is required. Then, the start from large quantity of radioactivity is frequently carried out to secure the activity sufficient for the imaging of organs. Therefore, the synthesis must be conducted by remote operation for the radiation protection of personnel. The development of an automatic synthesis apparatus for labeled-compounds is made along this line. Taking up the case of /sup 11/C-fatty acids, the following matters are described: synthetic reactions, the synthesis of /sup 11/C-fatty acids, an automatic synthesis apparatus for /sup 11/C-fatty acid made for trial, and applications.

Iida, S. (Japan Steel Works Ltd., Tokyo)

1981-03-01

149

Synthesis of [14CO]ellagic acid  

International Nuclear Information System (INIS)

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

1991-01-01

150

Methane-to-acetic acid synthesis matriculates at Penn State  

Energy Technology Data Exchange (ETDEWEB)

Direct conversion of methane to commercially valuable chemicals remains one of the grails of industrial chemistry. But scientists at Pennsylvania State University (University Park) appear to have made a significant step forward, reporting the direct catalytic conversion of methane into acetic acid under relatively mild conditions. Commercial acetic production involves a three-step process, including steam reforming of methane to synthesis gas (syngas) and the carbonylation of methanol of acetic acid.

Rotman, D.

1994-04-20

151

Synthesis of oligoribonucleic acid conjugates using a cyclooctyne phosphoramidite.  

Science.gov (United States)

The conjugation of a ribonucleic acid 16-mer with the cationic amphiphilic peptide penetratin and an anionic hyaluronan tetrasaccharide by means of Cu-free "click" chemistry is reported. The alkyne-functionalized 16-mer was prepared by automated solid-phase synthesis, using a newly developed strained cyclooctyne phosphoramidite in the final coupling. Cycloaddition of the alkyne functionalized RNA to the azide containing biomolecules led to a clean conversion into the corresponding nucleic acid conjugates. PMID:21049910

van Delft, Pieter; Meeuwenoord, Nico J; Hoogendoorn, Sascha; Dinkelaar, Jasper; Overkleeft, Herman S; van der Marel, Gijsbert A; Filippov, Dmitri V

2010-11-04

152

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

153

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

International Nuclear Information System (INIS)

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

2002-01-01

154

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

Directory of Open Access Journals (Sweden)

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.

Singh Biswajit K; Bisht Surendra S; Tripathi Rama P

2006-01-01

155

Synthesis and radioprotective properties of oxolinic acid derivatives  

International Nuclear Information System (INIS)

Synthesis of a number of esters and amides is performed to study influence of carboxyl modification function in oxolinic acid, which can essentially change molecular hydrophily, on antiradiation activity. The presented data show, that there are substances with clearly expressed radioprotective activity dialkylaminoethyl esters and amides.

1991-01-01

156

Enantioselective total synthesis of (-)-alpha-kainic acid.  

UK PubMed Central (United Kingdom)

An enantioselective total synthesis of (-)-alpha-kainic acid is described. Key steps are an Ir-catalyzed allylic amination with a propargylic amine to provide an enyne and a diastereoselective intramolecular Pauson-Khand reaction. Subsequent steps involve a Baeyer-Villiger reaction, reduction of the resulting lactone, and direct Jones oxidation of a silyl ether.

Farwick A; Helmchen G

2010-03-01

157

Enantioselective total synthesis of (-)-alpha-kainic acid.  

Science.gov (United States)

An enantioselective total synthesis of (-)-alpha-kainic acid is described. Key steps are an Ir-catalyzed allylic amination with a propargylic amine to provide an enyne and a diastereoselective intramolecular Pauson-Khand reaction. Subsequent steps involve a Baeyer-Villiger reaction, reduction of the resulting lactone, and direct Jones oxidation of a silyl ether. PMID:20148523

Farwick, Andreas; Helmchen, Günter

2010-03-01

158

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 tet...

Santosh Kumar Singh; Narendra Manne; Purna Chandra Ray; Manojit Pal

159

Process for manufacturing polybutylene terephthalate (PBT) catheter balloons  

UK PubMed Central (United Kingdom)

A processing technique and a composition which allow compositions of PBT polymers or copolymers to be formed into blow molded articles, especially medical balloons such as dilatation or stent placement balloons, from extruded tubular parisons. The process includes a longitudinal stretch step run at a temperature below the Tg of the polymeric material and a radial expansion step run at a temperature above the Tg of the polymeric material. During the longitudinal stretch step, the tubing is subjected to high internal pressure. In the composition a small amount of boric acid is added to the polybutylene terephthalate in a melt blend to give a formulation which has reduced crystallinity after extrusion and which can more readily fashioned into high strength blow molded articles than PBT by itself.Articles, which may be formed using the invention include medical device balloon articles in which the polymer consists essentially of PBT optionally blended with boric acid.

WANG LIXIAO; CHEN JIANHUA

160

Amino Acid Synthesis in a Supercritical Carbon Dioxide - Water System  

Directory of Open Access Journals (Sweden)

Full Text Available Mars is a CO2-abundant planet, whereas early Earth is thought to be also CO2-abundant. In addition, water was also discovered on Mars in 2008. From the facts and theory, we assumed that soda fountains were present on both planets, and this affected amino acid synthesis. Here, using a supercritical CO2/liquid H2O (10:1) system which mimicked crust soda fountains, we demonstrate production of amino acids from hydroxylamine (nitrogen source) and keto acids (oxylic acid sources). In this research, several amino acids were detected with an amino acid analyzer. Moreover, alanine polymers were detected with LC-MS. Our research lights up a new pathway in the study of life’s origin.

Kouki Fujioka; Yasuhiro Futamura; Tomoo Shiohara; Akiyoshi Hoshino; Fumihide Kanaya; Yoshinobu Manome; Kenji Yamamoto

2009-01-01

 
 
 
 
161

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

162

[Possible route for thiamine participation in fatty acid synthesis  

UK PubMed Central (United Kingdom)

The possibility of thiamine partaking in the synthesis of fatty acids through the functions unrelated to the catalytic properties of thiamine-diphosphate was studied. Rats kept on a fat-free ration devoid of thiamine were given thiamine of thiochrome with no vitaminic properties. The total fatty acids content in different tissues and incorporation therein of tagged acetate and pyruvate was determined, while the fatty acids composition of the liver was investigated by using gas chromatography. Thiamine and thiochrome produced a similar effect on a number of the study factors, i.e. they forced down the total acids level in the spleen, intensified incorporation of tagged acetate and pyruvate in fatty acids of the heart and uniformly changed the fatty acids composition in the liver. It is suggested that the unindirectional effects of thiamine and thiochrome is due to the oxidative transformation of thiamine into thiochrome.

Buko VU; Larin FS

1976-05-01

163

Glucose and Insulin Induction of Bile Acid Synthesis  

Science.gov (United States)

Bile acids facilitate postprandial absorption of nutrients. Bile acids also activate the farnesoid X receptor (FXR) and the G protein-coupled receptor TGR5 and play a major role in regulating lipid, glucose, and energy metabolism. Transgenic expression of cholesterol 7?-hydroxylase (CYP7A1) prevented high fat diet-induced diabetes and obesity in mice. In this study, we investigated the nutrient effects on bile acid synthesis. Refeeding of a chow diet to fasted mice increased CYP7A1 expression, bile acid pool size, and serum bile acids in wild type and humanized CYP7A1-transgenic mice. Chromatin immunoprecipitation assays showed that glucose increased histone acetylation and decreased histone methylation on the CYP7A1 gene promoter. Refeeding also induced CYP7A1 in fxr-deficient mice, indicating that FXR signaling did not play a role in postprandial regulation of bile acid synthesis. In streptozocin-induced type I diabetic mice and genetically obese type II diabetic ob/ob mice, hyperglycemia increased histone acetylation status on the CYP7A1 gene promoter, leading to elevated basal Cyp7a1 expression and an enlarged bile acid pool with altered bile acid composition. However, refeeding did not further increase CYP7A1 expression in diabetic mice. In summary, this study demonstrates that glucose and insulin are major postprandial factors that induce CYP7A1 gene expression and bile acid synthesis. Glucose induces CYP7A1 gene expression mainly by epigenetic mechanisms. In diabetic mice, CYP7A1 chromatin is hyperacetylated, and fasting to refeeding response is impaired and may exacerbate metabolic disorders in diabetes.

Li, Tiangang; Francl, Jessica M.; Boehme, Shannon; Ochoa, Adrian; Zhang, Youcai; Klaassen, Curtis D.; Erickson, Sandra K.; Chiang, John Y. L.

2012-01-01

164

On synthesis of silicoaluminotungstic heteropoly acid  

International Nuclear Information System (INIS)

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

2001-01-01

165

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; Burkhard König

2009-01-01

166

Synthesis of 2,3-substituted thienylboronic acids and esters.  

UK PubMed Central (United Kingdom)

A noncryogenic protocol for the synthesis of 2-substituted 3-thienylboronic acids and esters as well as 3-substituted 2-thienylboronic acids and esters has been developed. Electrophiles were introduced regiospecifically in the 2-position of 2,3-dibromothiophene and in the 3-position of 2-bromo-3-iodothiophene by halogen-magnesium exchange followed by quenching with electrophiles. Palladium-catalyzed borylation of the 2,3-substituted halothiophenes with pinacolborane and P(t-Bu)3 as ligand for Pd produced 9 and 10. The borylation protocol was tolerated by a range of functional groups; however, strongly electron-withdrawing substituents decreased the stability of the thienylboronic acids and esters.

Christophersen C; Begtrup M; Ebdrup S; Petersen H; Vedsø P

2003-11-01

167

Assaying for hydroxyl radicals: hydroxylated terephthalate is a superior fluorescence marker than hydroxylated benzoate.  

UK PubMed Central (United Kingdom)

Generation of hydroxyl radicals in terephthalate (benzene-1,4-dicarboxylic acid) solution yields fluorescent 2-hydroxy-terephthalate. The reaction product is stable for hours and can readily be assessed using standard fluorimeters. The efficiency, i.e. the relative increase of fluorescence per *OH radical, is about three times higher than that of the formation of salicylate (2-hydroxy-benzoate) from benzoic acid and approximately hundred-fold higher than that of the hydroxylation of phenylalanine. As the terephthalate molecule is symmetric with respect to ring-hydroxylation, only one isomer is formed; hence, mechanistic interpretation of the hydroxylation reaction is facilitated. The scavenging rate constant of terephthalate for *OH yielding the hydroxycyclohexadienyl adduct as first intermediate is close to the diffusion controlled limit (k = 3.3 x 10(9) M(-1) s(-1)). Therefore, competition of the detector molecule with biomolecules being present under physiological conditions is expected to be efficient. The assay can be used to detect 'free' *OH radicals produced by the radiolysis of water as well as 'hydroxyl analogous species' that have been suggested to arise from the interaction of complex-bound reduced metal with either oxygen or hydrogen peroxide, e.g. from Fenton reactions. Based on calibration with radiolytically generated hydroxyl radicals the detection limit of the method is estimated to be around 50 nmol/dm3. Terephthalate is classified non-toxic and hence may also prove useful for microdialysis and continuous flow experiments as observation of fluorescence is 'non-destructive' and the reporter substance does not necessarily have to be subjected to HPLC.

Saran M; Summer KH

1999-11-01

168

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

169

Synthesis of (±)-actinophyllic Acid and analogs: applications of cascade reactions and diverted total synthesis.  

UK PubMed Central (United Kingdom)

Actinophyllic acid is a biologically active indole alkaloid with a unique structural framework that incorporates five contiguous stereocenters. A total synthesis of (±)-actinophyllic acid has been completed that proceeds in only 10 steps from readily available, known compounds and with the isolation of nine intermediates. The synthesis features a novel cascade of reactions of N-stabilized carbocations with ?-nucleophiles to create the tetracyclic core of actinophyllic acid in a single chemical operation. This pivotal cascade sequence generates substructures of the actinophyllic acid core that are not otherwise accessible, and one key intermediate was modified to furnish several novel compounds having potentially promising anticancer activity, one of which induces cell death in a wide range of cancer cell lines.

Granger BA; Jewett IT; Butler JD; Hua B; Knezevic CE; Parkinson EI; Hergenrother PJ; Martin SF

2013-09-01

170

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.

2007-01-01

171

Inhibition of fatty acid synthesis in bovine mammary homogenate by palmitic acid is not a detergent effect.  

UK PubMed Central (United Kingdom)

Supplemental fat fed to dairy cows affects the fat composition of milk by reducing the yield of mammary synthesized fatty acids. The effect has been attributed to a potential allosteric inhibition of acetyl coenzyme-A, a key enzyme in fatty acid synthesis. In vitro experiments have demonstrated an inhibition of fatty acid synthesis when long-chain fatty acids are added to incubations. However, in vitro inhibition can result from a nonspecific detergent effect arising from an inherent physical property of fatty acids. An allosteric role for palmitic acid has not been tested in bovine mammary tissue. The objective of this experiment was to test the hypothesis that palmitic acid is an allosteric inhibitor of fatty acid synthesis in mammary tissue. We tested for a detergent effect by including a synthetic detergent, sodium dodecyl sulfate, under identical incubation conditions. A subcellular supernatant fraction of mammary tissue was used for incubations in the present experiment. The incubation system produced free fatty acids in a linear fashion for time and protein content. Results indicated that fatty acid synthesis was affected by the addition of palmitic acid to the incubations but not by caprylic acid, a short-chain fatty acid. Sodium dodecyl sulfate did not affect fatty acid synthesis at the concentrations used. The results of the present experiment indicate that palmitic acid inhibited fatty acid synthesis, and the effect was not the result of a detergent effect.

Wright TC; Cant JP; McBride BW

2002-03-01

172

75 FR 40784 - Polyethylene Terephthalate Film, Sheet, and Strip from the Republic of Korea: Preliminary Results...  

Science.gov (United States)

...Trade Administration [A-580-807] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet and strip...until no later than July 7, 2010. See Polyethylene Terephthalate Film, Sheet and...

2010-07-14

173

75 FR 49900 - Polyethylene Terephthalate Film, Sheet, and Strip From Brazil: Preliminary Results of Antidumping...  

Science.gov (United States)

...Trade Administration [A-351-841] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...order on PET film from Brazil. See Polyethylene Terephthalate Film, Sheet, and...

2010-08-16

174

76 FR 47540 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Preliminary Results of Antidumping...  

Science.gov (United States)

...Trade Administration [A-583-837] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...Value and Antidumping Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2011-08-05

175

75 FR 49902 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Preliminary Results of Antidumping...  

Science.gov (United States)

...Trade Administration [A-583-837] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...Value and Antidumping Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2010-08-16

176

75 FR 10758 - Polyethylene Terephthalate Film, Sheet and Strip from India: Initiation of Antidumping Duty and...  

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...Administration [A-533-824, C-533-825] Polyethylene Terephthalate Film, Sheet and Strip...countervailing duty (CVD) orders on Polyethylene Terephthalate Film, Sheet and Strip...Value and Antidumping Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2010-03-09

177

75 FR 75172 - Polyethylene Terephthalate Film, Sheet, and Strip From Brazil: Final Results of Antidumping Duty...  

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...Trade Administration [A-351-841] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...interested parties to comment. See Polyethylene Terephthalate Film, Sheet, and...

2010-12-02

178

76 FR 47546 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Preliminary Results of Antidumping...  

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...Trade Administration [A-533-824] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...Value and Antidumping Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2011-08-05

179

76 FR 30910 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Final Results of Countervailing...  

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...Trade Administration [C-533-825] Polyethylene Terephthalate Film, Sheet, and Strip...results of the new shipper review of polyethylene terephthalate film, sheet and strip...Background Since the issuance of Polyethylene Terephthalate Film, Sheet, and...

2011-05-27

180

76 FR 40325 - Polyethylene Terephthalate Film, Sheet, and Strip From the Republic of Korea: Preliminary Results...  

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...Trade Administration [A-580-807] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet and strip...no later than June 30, 2011. See Polyethylene Terephthalate Film, Sheet, and...

2011-07-08

 
 
 
 
181

76 FR 61085 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China: Extension...  

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...Trade Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...results of the administrative review of polyethylene terephthalate film, sheet, and strip...results of the review by 60 days. See Polyethylene Terephthalate Film, Sheet, and...

2011-10-03

182

76 FR 48122 - Polyethylene Terephthalate Film, Sheet, and Strip From Brazil: Preliminary Results of Antidumping...  

Science.gov (United States)

...Trade Administration [A-351-841] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...order on PET film from Brazil. See Polyethylene Terephthalate Film, Sheet, and...

2011-08-08

183

75 FR 78968 - Polyethylene Terephthalate Film, Sheet, and Strip From the United Arab Emirates: Preliminary...  

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...Trade Administration [A-520-803] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...order on PET Film from the UAE. See Polyethylene Terephthalate Film, Sheet, and...

2010-12-17

184

75 FR 49893 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China...  

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...Trade Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...1\\ See also Polyethylene Terephthalate Film, Sheet, and...

2010-08-16

185

76 FR 9745 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Final Results of Antidumping Duty...  

Science.gov (United States)

...Trade Administration [A-583-837] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film (PET Film) from Taiwan. See Polyethylene Terephthalate Film, Sheet, and...

2011-02-22

186

78 FR 9668 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan: Final Results of Antidumping Duty...  

Science.gov (United States)

...Trade Administration [A-533-824] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film (PET Film) from...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2013-02-11

187

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

Science.gov (United States)

...Trade Administration [A-583-837] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty administrative review of polyethylene terephthalate film, sheet, and strip...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2011-04-04

188

78 FR 9670 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Final Results of Administrative...  

Science.gov (United States)

...Trade Administration [A-533-824] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film (PET Film) from...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2013-02-11

189

75 FR 80457 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...  

Science.gov (United States)

...Trade Administration [A-533-824] Polyethylene Terephthalate Film, Sheet and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet and strip...through December 31, 2009. See Polyethylene Terephthalate Film, Sheet and...

2010-12-22

190

76 FR 9753 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China: Final...  

Science.gov (United States)

...Trade Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2011-02-22

191

78 FR 48651 - Polyethylene Terephthalate Film, Sheet, and Strip From Taiwan; Preliminary Results of Antidumping...  

Science.gov (United States)

...Trade Administration [A-583-837] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...1\\ See Polyethylene Terephthalate Film, Sheet and...

2013-08-09

192

78 FR 48147 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Preliminary Results of...  

Science.gov (United States)

...Trade Administration [C-533-825] Polyethylene Terephthalate Film, Sheet, and Strip...countervailing duty (CVD) order on polyethylene terephthalate film, sheet and strip...gauges of raw, pretreated, or primed polyethylene terephthalate film, sheet and...

2013-08-07

193

78 FR 2365 - Polyethylene Terephthalate Film, Sheet and Strip From India: Partial Rescission of Antidumping...  

Science.gov (United States)

...Trade Administration [A-533-824] Polyethylene Terephthalate Film, Sheet and Strip...the antidumping duty (AD) order on polyethylene terephthalate film, sheet and strip...Plastics (America), Inc. \\3\\ See Polyethylene Terephthalate (PET) Film,...

2013-01-11

194

75 FR 79336 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...  

Science.gov (United States)

...Trade Administration [C-533-825] Polyethylene Terephthalate Film, Sheet and Strip...under the countervailing duty order on polyethylene terephthalate film, sheet and strip...through December 31, 2009. See Polyethylene Terephthalate Film, Sheet and...

2010-12-20

195

78 FR 48143 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Preliminary Results of Antidumping...  

Science.gov (United States)

...Trade Administration [A-533-824] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...Antidumping Duty Administrative Review: Polyethylene Terephthalate Film, Sheet, and...

2013-08-07

196

77 FR 73428 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China...  

Science.gov (United States)

...Trade Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...Antidumping Duty Administrative Review: Polyethylene Terephthalate Film, Sheet, and...

2012-12-10

197

76 FR 30908 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Final Results of Antidumping Duty...  

Science.gov (United States)

...Trade Administration [A-533-824] Polyethylene Terephthalate Film, Sheet, and Strip...results of the new shipper review of polyethylene terephthalate film, sheet and strip...Background Since the issuance of Polyethylene Terephthalate Film, Sheet, and...

2011-05-27

198

75 FR 14423 - Polyethylene Terephthalate Film, Sheet and Strip from Taiwan: Extension of Time Limit for...  

Science.gov (United States)

...Trade Administration [A-583-837] Polyethylene Terephthalate Film, Sheet and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet and strip...review of the antidumping order on polyethylene terephthalate film, sheet and...

2010-03-25

199

76 FR 47558 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Preliminary Results of...  

Science.gov (United States)

...Trade Administration [C-533-825] Polyethylene Terephthalate Film, Sheet, and Strip...countervailing duty (CVD) order on polyethylene terephthalate film, sheet and strip...Notice of Countervailing Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2011-08-05

200

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

Science.gov (United States)

...Trade Administration [C-533-825] Polyethylene Terephthalate Film, Sheet, and Strip...of the countervailing duty order on polyethylene terephthalate film, sheet, and strip...2007 through December 31, 2007. See Polyethylene Terephthalate Film, Sheet, and...

2010-02-10

 
 
 
 
201

75 FR 81574 - Polyethylene Terephthalate Film, Sheet, and Strip From India: Preliminary Results of...  

Science.gov (United States)

...Trade Administration [C-533-825] Polyethylene Terephthalate Film, Sheet, and Strip...countervailing duty (CVD) order on polyethylene terephthalate film, sheet and strip...Notice of Countervailing Duty Order: Polyethylene Terephthalate Film, Sheet and...

2010-12-28

202

78 FR 50029 - Polyethylene Terephthalate Film, Sheet and Strip From Brazil: Preliminary Results of Antidumping...  

Science.gov (United States)

...Trade Administration [A-351-841] Polyethylene Terephthalate Film, Sheet and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet and strip...Antidumping Duty Administrative Review of Polyethylene Terephthalate Film, Sheet and...

2013-08-16

203

78 FR 35245 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China: Final...  

Science.gov (United States)

...Trade Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2013-06-12

204

75 FR 65450 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...  

Science.gov (United States)

...Trade Administration [A-533-824] Polyethylene Terephthalate Film, Sheet and Strip...under the antidumping duty order on polyethylene terephthalate film, sheet and strip...2009 through December 31, 2009. See Polyethylene Terephthalate Film, Sheet and...

2010-10-25

205

75 FR 52717 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...  

Science.gov (United States)

...Trade Administration [A-533-824] Polyethylene Terephthalate Film, Sheet and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet and strip...2009 through December 31, 2009. See Polyethylene Terephthalate Film, Sheet and...

2010-08-27

206

75 FR 69400 - Polyethylene Terephthalate Film, Sheet and Strip From India: Extension of Time Limit for...  

Science.gov (United States)

...Trade Administration [C-533-825] Polyethylene Terephthalate Film, Sheet and Strip...under the countervailing duty order on polyethylene terephthalate film, sheet and strip...through December 31, 2009. See Polyethylene Terephthalate Film, Sheet and...

2010-11-12

207

76 FR 57715 - Polyethylene Terephthalate Film, Sheet, and Strip From the Republic of Korea: Revocation of...  

Science.gov (United States)

...Trade Administration [A-580-807] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...existing antidumping duty order on polyethylene terephthalate film, sheet, and...

2011-09-16

208

78 FR 47276 - Polyethylene Terephthalate (PET) Film, Sheet, and Strip From India: Final Results of the...  

Science.gov (United States)

...Trade Administration [C-533-825] Polyethylene Terephthalate (PET) Film, Sheet...of the countervailing duty order on polyethylene terephthalate (PET) film, sheet...Notice of Countervailing Duty Order: Polyethylene Terephthalate Film, Sheet, and...

2013-08-05

209

75 FR 69629 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China: Extension...  

Science.gov (United States)

...Trade Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...antidumping duty administrative review on polyethylene terephthalate film, sheet, and strip...preliminary results of this review. See Polyethylene Terephthalate Film, Sheet, and...

2010-11-15

210

5-Aminolevulinic acid synthesis in Escherichia coli.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A hemA mutant of Escherichia coli containing a multicopy plasmid which complemented the mutation excreted 5-aminolevulinic acid (ALA) into the medium. [1-14C]glutamate was substantially incorporated into ALA by this strain, whereas [2-14C]glycine was not. Periodate degradation of labeled ALA showed ...

Li, J M; Brathwaite, O; Cosloy, S D; Russell, C S

211

Inhibition of polyketide synthesis in Alternaria alternata by the fatty acid synthesis inhibitor cerulenin.  

UK PubMed Central (United Kingdom)

The fatty acid synthase inhibitor cerulenin (50 to 100 micrograms/ml) inhibited production of the polyketide mycotoxins alternariol (AOH) and alternariol monomethyl ether (AME) by the mold Alternaria alternata. The results suggested that AOH synthesis was inhibited by a direct mechanism by cerulenin, whereas production of AME was probably limited by a shortage of the precursor AOH.

Hiltunen M; Söderhäll K

1992-03-01

212

Inhibition of polyketide synthesis in Alternaria alternata by the fatty acid synthesis inhibitor cerulenin.  

Science.gov (United States)

The fatty acid synthase inhibitor cerulenin (50 to 100 micrograms/ml) inhibited production of the polyketide mycotoxins alternariol (AOH) and alternariol monomethyl ether (AME) by the mold Alternaria alternata. The results suggested that AOH synthesis was inhibited by a direct mechanism by cerulenin, whereas production of AME was probably limited by a shortage of the precursor AOH.

Hiltunen, M; Soderhall, K

1992-01-01

213

Inhibition of polyketide synthesis in Alternaria alternata by the fatty acid synthesis inhibitor cerulenin.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The fatty acid synthase inhibitor cerulenin (50 to 100 micrograms/ml) inhibited production of the polyketide mycotoxins alternariol (AOH) and alternariol monomethyl ether (AME) by the mold Alternaria alternata. The results suggested that AOH synthesis was inhibited by a direct mechanism by cerulenin...

Hiltunen, M; Söderhäll, K

214

Inhibition of rotavirus replication by downregulation of fatty acid synthesis.  

UK PubMed Central (United Kingdom)

Recently the recruitment of lipid droplets (LDs) to sites of rotavirus (RV) replication was reported. LDs are polymorphic organelles that store triacylglycerols, cholesterol and cholesterol esters. The neutral fats are derived from palmitoyl-CoA, synthesized via the fatty acid biosynthetic pathway. RV-infected cells were treated with chemical inhibitors of the fatty acid biosynthetic pathway, and the effects on viral replication kinetics were assessed. Treatment with compound C75, an inhibitor of the fatty acid synthase enzyme complex (FASN), reduced RV infectivity 3.2-fold (P = 0.07) and modestly reduced viral RNA synthesis (1.2-fold). Acting earlier in the fatty acid synthesis pathway, TOFA [5-(Tetradecyloxy)-2-furoic acid] inhibits the enzyme acetyl-CoA carboxylase 1 (ACC1). TOFA reduced the infectivity of progeny RV 31-fold and viral RNA production 6-fold. The effect of TOFA on RV infectivity and RNA replication was dose-dependent, and infectivity was reduced by administering TOFA up to 4 h post-infection. Co-treatment of RV-infected cells with C75 and TOFA synergistically reduced viral infectivity. Knockdown by siRNA of FASN and ACC1 produced findings similar to those observed by inhibiting these proteins with the chemical compounds. Inhibition of fatty acid synthesis using a range of approaches uniformly had a more marked impact on viral infectivity than on viral RNA yield, inferring a role for LDs in virus assembly and/or egress. Specific inhibitors of fatty acid metabolism may help pinpoint the critical structural and biochemical features of LDs that are essential for RV replication, and facilitate the development of antiviral therapies.

Gaunt ER; Cheung W; Richards JE; Lever A; Desselberger U

2013-06-01

215

Photochemical modification of polyethylene terephthalate surface  

Science.gov (United States)

The prospect of obtaining desired surface-mediated characteristics while retaining bulk-mediated physical properties and avoiding potential environmental issues with wet chemical technology lends considerable appeal to photochemical approaches to surface modification. We undertook a combined experimental and computational approach to investigate the effect of deep UV irradiation on the polyethylene terephthalate (PET) surface. Its response to 172 nm UV from a xenon examiner lamp in the absence of oxygen was characterized with X-ray Photoelectron Spectroscopy (XPS), Time of Flight/Secondary Ion Mass Spectrometry (ToF/SIMS), transmission infrared spectroscopy (IR), and Atomic Force Microscopy (AFM). The surface chemistry details suggested that the primary photochemical reactions involved a Norrish type I based decarbonylation and a Norrish type II process yielding terminal carboxylic acid groups, consistent with the possible photochemistry from n-pi* type lowest singlet excited states of PET according to the computational modeling results. By directly populating n-pi* type excited states, 172 nm UV promoted effective surface photochemistry of PET with further helps from the high UV absorptivity and the high surface mobility of the molecules. Utilizing this active surface radical chemistry, a new grafting strategy was developed to impart desirable functional properties to the surface. A broad range of grafting chemicals can be employed in their vapor forms, demonstrated with an alkene or an alkane. Surface analysis with XPS, ToF/SIMS, AFM, and water contact angle measurements confirmed the effectiveness of the approach, supporting the notion of the surface radical initiated processes. A potentially useful anti-stain/soil coating was developed by grafting with a fluorocarbon species. Surface analysis suggested that the grafted fluorocarbon formed a nano-scale self-assembled monolayer. The coating had a similar water contact angle as that of a pure fluoropolymer but a better oil repellency due to the special molecular orientation in the graft layer. A potential antimicrobial application was demonstrated with amine chemicals. Structure characterization and computational modeling results suggested that the photochemistry of the UV active grafting chemicals also played an important role in the grafting process. A double bond structure in the amine species protected the amine functional groups and the resulting coating demonstrated antimicrobial activity against E. coli.

Zhu, Zhengmao

216

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. D. Jumbam; W. Masamba; N. Mbebe

2013-01-01

217

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

UK PubMed Central (United Kingdom)

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

Manes SH; Pruss GJ; Drlica K

1983-07-01

218

Cancer chemotherapy: targeting folic acid synthesis  

Directory of Open Access Journals (Sweden)

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

Nicole Hagner; Markus Joerger

2010-01-01

219

Cancer chemotherapy: targeting folic acid synthesis.  

Science.gov (United States)

Antifolates are structural analogs of folates, essential one-carbon donors in the synthesis of DNA in mammalian cells. Antifolates are inhibitors of key enzymes in folate metabolism, namely dihydrofolate reductase, ?-glycinamide ribonucleotide transformylase, 5'-amino-4'-imidazolecarboxamide ribonucleotide transformylase, and thymidylate synthetase. Methotrexate is one of the earliest anticancer drugs and is extensively used in lymphoma, acute lymphoblastic leukemia, and osteosarcoma, among others. Pemetrexed has been approved in combination with cisplatin as first-line treatment for advanced non-squamous-cell lung cancer, as a single agent for relapsed non-small-cell lung cancer after platinum-containing chemotherapy, and in combination with cisplatin for the treatment of pleural mesothelioma. Raltitrexed is approved in many countries (except in the United States) for advanced colorectal cancer, but its utilization is mainly limited to patients intolerant to 5-fluorouracil. Pralatrexate has recently been approved in the United States for relapsed or refractory peripheral T-cell lymphoma. This article gives an overview of the cellular mechanism, pharmacology, and clinical use of classical and newer antifolates and discusses some of the main resistance mechanisms to antifolate drugs. PMID:21301589

Hagner, Nicole; Joerger, Markus

2010-11-19

220

Cancer chemotherapy: targeting folic acid synthesis.  

UK PubMed Central (United Kingdom)

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

Hagner N; Joerger M

2010-01-01

 
 
 
 
221

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthesis under microwave irradiation, characterization and application of new alkyliminodimethylenediphosphonic acids in solvent extraction of uranium (VI) have been investigated. The alkyliminodimethylenediphosphonic acids synthesized were: hexadecyliminodimethylenediphosphonic acid (HIDMP, H&...

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

222

SYNTHESIS OF HYDROGELS CONTAINING INDOLBUTYRIC ACID AS ROOTING AUXIN  

Directory of Open Access Journals (Sweden)

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

DIETER KLATTENHOFF; RENE ESCOBAR; EDUARDO ALISTE

2006-01-01

223

Microwave-Promoted synthesis of novel N-Arylanthranilic acids  

Scientific Electronic Library Online (English)

Full Text Available 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 substituintes 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.

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

2008-01-01

224

SYNTHESIS OF HYDROGELS CONTAINING INDOLBUTYRIC ACID AS ROOTING AUXIN  

Scientific Electronic Library Online (English)

Full Text Available 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

KLATTENHOFF, DIETER; ESCOBAR, RENE; ALISTE, EDUARDO

2006-06-01

225

Design and Synthesis of a Dual Linker for Solid Phase Synthesis of Oleanolic Acid Derivatives  

Directory of Open Access Journals (Sweden)

Full Text Available A hydrophilic amino-terminated poly(ethylene glycol)-type dual linker for solid phase synthesis of oleanolic acid derivatives using trityl chloride resin was designed and synthesized for the first time. Model reactions in both liquid and solid phase were performed to show the feasibility of its selective cleavage at two different sites. The biological assay results indicated that the long and flexible alkyl ether functionality in the linker is less likely to be critical for the binding event. Following the successful solid-phase synthesis of model compounds, the potential of this dual linker in reaction monitoring and target identification is deemed worthy of further study.

Shaorong Wang; Weishuo Fang

2011-01-01

226

In Vitro Fatty Acid Synthesis and Complex Lipid Metabolism in the Cyanobacterium Anabaena variabilis: I. Some Characteristics of Fatty Acid Synthesis.  

UK PubMed Central (United Kingdom)

In vitro fatty acid synthesis was examined in crude cell extracts, soluble fractions, and 80% (NH(4))(2)SO(4) fractions from Anabaena variabilis M3. Fatty acid synthesis was absolutely dependent upon acyl carrier protein and required NADPH and NADH. Moreover, fatty acid synthesis and elongation occurred in the cytoplasm of the cell. The major fatty acid products were palmitic acid (16:0) and stearic acid (18:0). Of considerable interest, both stearoyl-acyl carrier protein and stearoyl-coenzyme A desaturases were not detected in any of the fractions from A. variabilis. The similarities and differences in fatty acid synthesis between A. variabilis and higher plant tissues are discussed with respect to the endosymbiotic theory of chloroplast evolution.

Lem NW; Stumpf PK

1984-01-01

227

A Study on Amino Acids: Synthesis of Alpha-Aminophenylacetic Acid (Phenylglycine) and Determination of its Isoelectric Point.  

Science.gov (United States)

Background information and procedures are provided for an experimental study on aminophenylacetic acid (phenylglycine). These include physical chemistry (determination of isoelectric point by pH measurement) and organic chemistry (synthesis of an amino acid in racemic form) experiments. (JN)

Barrelle, M.; And Others

1983-01-01

228

[Synthesis and characterization of protocatechuic acid derivants].  

UK PubMed Central (United Kingdom)

To explore the effects of protocatechuic acid (PCA) and its derivants on angiogenesis of the chick embryo chorioallantoic membrane (CAM) and scavenging DPPH radical in vitro. The protection of benzyl and alkaline hydrolysis of benzyl ester were employed. The structures of PCA-1, PCA-2 and PCA-3, the derivates of PCA, were elucidated by 1H, 13C-NMR and MS data The bioactivity of PCA and its derivants was evaluated on the models of DPPH radical and chick embryo chorioallantoic membrane (CAM), respectively. PCA and PCA-1 showed the best activity of scavenging DPPH radical among all the compounds. In contrast to PCA-2, PCA and PCA-3 displayed inhibition to angiogenesis (P < 0.001). Pyrocatechol hydroxyl is the active site of PCA on scavenging DPPH radical in vitro. PCA with carboxyl and without pyrocatechol hydroxyl seems to show promotion to angiogenesis, but it needs more evidences.

Li QS; Wang W; Han QJ; Wang PL; Li Q; Lei HM

2013-01-01

229

Convergent approach to complex spirocyclic pyrans: practical synthesis of the oxa-pinnaic acid core.  

UK PubMed Central (United Kingdom)

The enantioselective synthesis of the oxa-pinnaic acid framework has been achieved through internal asymmetric induction. The synthetic strategy pursued illustrates the adaptability of the Achmatowicz oxidative rearrangement for the synthesis of complex spirocyclic pyrans starting from tertiary alcohols.

Ferrari FD; Pasqua AE; Ledgard AJ; Marquez R

2013-06-01

230

Lettuce seed germination: modulation of pregermination protein synthesis by gibberellic Acid, abscisic Acid, and cytokinin.  

UK PubMed Central (United Kingdom)

Protein synthesis in gibberellin-treated lettuce (Lactuca sativa) seeds has been studied during the lag phase between the beginning of imbibition and the first signs of radicle protrusion. When compared to the water-imbibed controls, both polyribosome populations and radioactive leucine incorporation into protein increase in the embryos of GA(3)- induced seeds early in the imbibition period. Since these results are contradictory to previously published studies, the reasons for the differences are outlined and various alternative possibilities eliminated. The protocol for protein extraction, particularly the speed at which the supernatant from the seed homogenate is cleared, is important for demonstrating the GA(3)-mediated changes. Embryos maintained in the dormant state by abscisic acid still conduct considerable amounts of protein synthesis, and this is enhanced by concentrations of 6-benzylaminopurine which also promote germination. Therefore, the actions of GA(3), abscisic acid, and cytokinin on lettuce seed germination are mediated, directly or indirectly, via protein synthesis.

Fountain DW; Bewley JD

1976-10-01

231

Biphasic effect of oleic acid on hepatic cholesterol synthesis  

International Nuclear Information System (INIS)

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

1990-02-26

232

Cholic acid mediates negative feedback regulation of bile acid synthesis in mice  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Cholesterol is converted into dozens of primary and secondary bile acids through pathways subject to negative feedback regulation mediated by the nuclear receptor farnesoid X receptor (FXR) and other effectors. Disruption of the sterol 12?-hydroxylase gene (Cyp8b1) in mice prevents the synthesis of ...

Li-Hawkins, Jia; Gåfvels, Mats; Olin, Maria; Lund, Erik G.; Andersson, Ulla; Schuster, Gertrud; Björkhem, Ingemar

233

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

234

Isonicotinic acid hydrazide induced changes and inhibition in mycolic acid synthesis in Nocardia and related taxa.  

UK PubMed Central (United Kingdom)

The mycolic acid compositions of Nocardia rubra and related bacteria grown in media containing different concentrations of antituberculous isonicotinic acid hydrazide (INH) were determined in detail by gas chromatography-mass spectrometry. On the basis of molecular species composition, average carbon numbers of mycolic acids were calculated. In Nocardia rubra, N. lutea and Rhodococcus rhodochrous IFO-13161, the ratio of mycolic to non-mycolic fatty acids and the average carbon numbers of mycolic acids were decreased at the INH concentrations of higher than 1 microgram/ml, paralleling with the significant inhibition of growth. In above three species the synthesis of longer chain mycolic acids (longer than C44 or C46 ) was inhibited more significantly than shorter homologues such as C38 or C40 . In contrast, neither growth inhibition nor change in corynomycolic acid composition was observed in Corynebacteria xerosis and Rhodococcus rhodochrous IFO-13165 at the concentration region of INH up to 100 micrograms/ml. The direct mass fragmentographic analysis of the trimethylsilylated (TMS) derivatives of mycolic acid methyl esters, monitoring [M-15] ions of individual molecular species, revealed that the chain shortening of total mycolic acid molecule by INH occurred more greatly in more highly unsaturated subclasses than in less unsaturated subclasses. Furthermore, mass fragmentographic analysis, monitoring fragment ions (A) and (B), due to straight chain and branched chain alkyl units, respectively, demonstrated the inhibition of mycolic acids was not attributed to the shortening of alpha-alkyl chain, but to the inhibition of chain elongation of C28 to C32 straight chain meromycolic acids. It was also indicated the amounts of trehalose mono- and di- mycolate (cord factor) decreased significantly with the addition of INH (1 to 20 micrograms/ml) in the above strains. From the results obtained above, INH appeared to inhibit the synthesis of mycolic acids longer than C44 or C46 specifically by inhibiting chain elongation or desaturation of precursor long chain fatty acids longer than C28 or C30.

Tomiyasu I; Yano I

1984-04-01

235

Photochemical Synthesis of the Bioconjugate Folic Acid-Gold Nanoparticles  

Directory of Open Access Journals (Sweden)

Full Text Available 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.

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

2013-01-01

236

Boronic acid-containing hydrogels: synthesis and their applications.  

UK PubMed Central (United Kingdom)

Boronic acid-containing hydrogels are important intelligent materials. With the introduction of boronic acid functionality, these hydrogels exhibit a lot of interesting properties, such as glucose-sensitivity, reversibility and self-healing. These materials have found important applications in many areas, especially in biomedical areas. This paper aims to provide an overview of the current state of the art of the study in this area. We review the synthesis and properties of various boronic acid-containing hydrogels, including macroscopic hydrogels, microgels and layer-by-layer self-assembled films. Their applications were described, with an emphasis on the design of various glucose sensors and self-regulated insulin delivery devices. New development in this area was highlighted. Problems and the new directions were discussed.

Guan Y; Zhang Y

2013-09-01

237

Boronic acid-containing hydrogels: synthesis and their applications.  

UK PubMed Central (United Kingdom)

Boronic acid-containing hydrogels are important intelligent materials. With the introduction of boronic acid functionality, these hydrogels exhibit a lot of interesting properties, such as glucose-sensitivity, reversibility and self-healing. These materials have found important applications in many areas, especially in biomedical areas. This paper aims to provide an overview of the current state of the art of the study in this area. We review the synthesis and properties of various boronic acid-containing hydrogels, including macroscopic hydrogels, microgels and layer-by-layer self-assembled films. Their applications were described, with an emphasis on the design of various glucose sensors and self-regulated insulin delivery devices. New development in this area was highlighted. Problems and the new directions were discussed.

Guan Y; Zhang Y

2013-07-01

238

Synthesis of 2,3-substituted thienylboronic acids and esters.  

Science.gov (United States)

A noncryogenic protocol for the synthesis of 2-substituted 3-thienylboronic acids and esters as well as 3-substituted 2-thienylboronic acids and esters has been developed. Electrophiles were introduced regiospecifically in the 2-position of 2,3-dibromothiophene and in the 3-position of 2-bromo-3-iodothiophene by halogen-magnesium exchange followed by quenching with electrophiles. Palladium-catalyzed borylation of the 2,3-substituted halothiophenes with pinacolborane and P(t-Bu)3 as ligand for Pd produced 9 and 10. The borylation protocol was tolerated by a range of functional groups; however, strongly electron-withdrawing substituents decreased the stability of the thienylboronic acids and esters. PMID:14629185

Christophersen, Claus; Begtrup, Mikael; Ebdrup, Søren; Petersen, Henning; Vedsø, Per

2003-11-28

239

Boronic acid-containing hydrogels: synthesis and their applications.  

Science.gov (United States)

Boronic acid-containing hydrogels are important intelligent materials. With the introduction of boronic acid functionality, these hydrogels exhibit a lot of interesting properties, such as glucose-sensitivity, reversibility and self-healing. These materials have found important applications in many areas, especially in biomedical areas. This paper aims to provide an overview of the current state of the art of the study in this area. We review the synthesis and properties of various boronic acid-containing hydrogels, including macroscopic hydrogels, microgels and layer-by-layer self-assembled films. Their applications were described, with an emphasis on the design of various glucose sensors and self-regulated insulin delivery devices. New development in this area was highlighted. Problems and the new directions were discussed. PMID:23860617

Guan, Ying; Zhang, Yongjun

2013-09-23

240

Lipase-catalyzed synthesis of fattythioic acids from palm oil.  

UK PubMed Central (United Kingdom)

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%.

Al-Mulla EA

2011-01-01

 
 
 
 
241

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

242

[Effect of folic acid deficiency on the synthesis of pteroylpolyglutamates  

UK PubMed Central (United Kingdom)

In order to evaluate the effect of folate deficiency on pteroylpolyglutamate synthesis in rat liver, the hepatic and urinary content of reduced folates, the distribution of pteroylpolyglutamates and the incorporation of i.p. injected 3H folic acid in polyglutamates have been studied. In deficient rats the hepatic content of reduced folates and the urinary amounts of reduced metabolites are lower and do not increase after vitamin treatment. Longer chain pteroylpolyglutamates are severely depleted and their content is not significantly modified by folic acid treatment. The percentage of labelled folic acid incorporated into pteroylglutamates is markedly decreased. The inability of deficient rat liver to synthesize polyglutamates might be ascribed to the decrease of pteroylpolyglutamate synthetase activity, and/or to the lower availability of tetrahydrofolates, the preferred substrates for the enzyme.

Formiggini G; Bovina C; Tolomelli B; Marchetti M

1983-01-01

243

Bioorganic Synthesis; Monosodium Glutamate and Other Amino Acids  

Science.gov (United States)

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

244

Synthesis of [11C-methyl]-?-aminoisobutyric acid (AIB)  

International Nuclear Information System (INIS)

[en] Alpha-aminoisobutyric acid (AIB) labeled with the cyclotron-produced, positron-emitting radionuclide 11C has been synthesized with the label in the alpha-methyl group. Our previously published synthesis of [11C] AIB in the carboxyl position from [11C] HCN requires a rigorous quality assurance program to ensure that the concentration of cyanide in the final product is below certain levels. This can be avoided using the method described here with [11C] CH3. The radiochemical yield calculated to end of bombardment (EOB) was 45-55% from [11C] CO2 with radiochemical purity of [11C-methyl] AIB exceeding 99%. Synthesis times from [11C] CO2 were about 55 min. Specific activities of 1 Ci/?mol were achieved on average. It has been shown that [11C-carboxyl] AIB is a useful imaging agent in patients with soft tissue cancers and melanoma, and it demonstrates tumor uptake in a spectrum of other animal tumor models. Because AIB is a nonmetabolized amino acid, [11C-methyl] AIB should be equally as useful. Either agent can be employed for the quantification of the A-type amino acid transport system in vivo with PET

1996-01-01

245

Stereoselective synthesis of uridine-derived nucleosyl amino acids.  

Science.gov (United States)

Novel hybrid structures of 5'-deoxyuridine and glycine were conceived and synthesized. Such nucleosyl amino acids (NAAs) represent simplified analogues of the core structure of muraymycin nucleoside antibiotics, making them useful synthetic building blocks for structure-activity relationship (SAR) studies. The key step of the developed synthetic route was the efficient and highly diastereoselective asymmetric hydrogenation of didehydro amino acid precursors toward protected NAAs. It was anticipated that the synthesis of unprotected muraymycin derivatives via this route would require a suitable intermediate protecting group at the N-3 of the uracil base. After initial attempts using PMB- and BOM-N-3 protection, both of which resulted in problematic deprotection steps, an N-3 protecting group-free route was envisaged. In spite of the pronounced acidity of the uracil-3-NH, this route worked equally efficient and with identical stereoselectivities as the initial strategies involving N-3 protection. The obtained NAA building blocks were employed for the synthesis of truncated 5'-deoxymuraymycin analogues. PMID:22059552

Spork, Anatol P; Wiegmann, Daniel; Granitzka, Markus; Stalke, Dietmar; Ducho, Christian

2011-11-21

246

Synthesis and properties of fatty acid starch esters.  

UK PubMed Central (United Kingdom)

Being completely bio-based, fatty acid starch esters (FASEs) are attractive materials that represent an alternative to crude oil-based plastics. In this study, two synthesis methods were compared in terms of their efficiency, toxicity and, especially, product solubility with starch laurate (C12) as model compound. Laurates (DS>2) were obtained through transesterification of fatty acid vinylesters in DMSO or reaction with fatty acid chlorides in pyridine. The latter lead to higher DS-values in a shorter reaction time. But due to the much better solubility of the products compared to lauroyl chloride esterified ones, vinylester-transesterification was preferred to optimize reaction parameters, where reaction time could be shortened to 2h. FASEs C6-C18 were also successfully prepared via transesterification. To determine the DS of the resulting starch laurates, the efficient ATR-IR method was compared with common methods (elementary analysis, (1)H NMR). Molar masses (Mw) of the highly soluble starch laurates were analyzed using SEC-MALLS (THF). High recovery rates (>80%) attest to the outstanding solubility of products obtained through transesterification, caused by a slight disintegration during synthesis. Particle size distributions (DLS) demonstrated stable dissolutions in CHCl3 of vinyl laurate esterified - contrary to lauroyl chloride esterified starch. For all highly soluble FASEs (C6-C18), formation of concentrated solutions (10wt%) is feasible.

Winkler H; Vorwerg W; Wetzel H

2013-10-01

247

Reutilization of fatty acid carbons for lung lipid synthesis.  

UK PubMed Central (United Kingdom)

The utilization of glucose, palmitate, and oleate for the synthesis of lung lipids was studied in isolated rat lungs. Lungs were ventilated with 5% CO2 in air and perfused for 100 min with a Krebs-Ringer bicarbonate buffer (pH 7.4), containing 3% fatty acid-free albumin and either 5.6 mM [U-14C]glucose or 0.25 mM [1-14C]palmitate, or 0.25 mM [1-14C]-oleate. At the end of 100 min of perfusion with these precursors, between 73 and 85% of total lipid 14C was recovered as phospholipid. Glucose carbon was mainly incorporated into triglyceride fatty acids (TG-FA) and phosphatidylcholine fatty acids (PC-FA) of 16- and 18-carbon chain length. After perfusion with [14C]palmitate and [14C]oleate, only 65 and 20% of 14C was recovered as PC 16-carbon and 18-carbon FA, respectively. The remaining 14C was mainly recovered as FA shorter than the 14C precursors. Schmidt degradation analysis of lipid FA demonstrated considerable labeling of alkyl carbons on perfusion with the carboxyl-labeled precursors, indicating that FA degradation products were used for synthesis of lipid FA. This process was enhanced on addition of glucose to the perfusate.

Rabinowitz JL; Cardwell T; Bassett DJ

1981-04-01

248

Synthesis and properties of fatty acid starch esters.  

Science.gov (United States)

Being completely bio-based, fatty acid starch esters (FASEs) are attractive materials that represent an alternative to crude oil-based plastics. In this study, two synthesis methods were compared in terms of their efficiency, toxicity and, especially, product solubility with starch laurate (C12) as model compound. Laurates (DS>2) were obtained through transesterification of fatty acid vinylesters in DMSO or reaction with fatty acid chlorides in pyridine. The latter lead to higher DS-values in a shorter reaction time. But due to the much better solubility of the products compared to lauroyl chloride esterified ones, vinylester-transesterification was preferred to optimize reaction parameters, where reaction time could be shortened to 2h. FASEs C6-C18 were also successfully prepared via transesterification. To determine the DS of the resulting starch laurates, the efficient ATR-IR method was compared with common methods (elementary analysis, (1)H NMR). Molar masses (Mw) of the highly soluble starch laurates were analyzed using SEC-MALLS (THF). High recovery rates (>80%) attest to the outstanding solubility of products obtained through transesterification, caused by a slight disintegration during synthesis. Particle size distributions (DLS) demonstrated stable dissolutions in CHCl3 of vinyl laurate esterified - contrary to lauroyl chloride esterified starch. For all highly soluble FASEs (C6-C18), formation of concentrated solutions (10wt%) is feasible. PMID:23987337

Winkler, Henning; Vorwerg, Waltraud; Wetzel, Hendrik

2013-06-07

249

Synthesis and Radioprotective Properties of Pulvinic Acid Derivatives  

International Nuclear Information System (INIS)

[en] A high-throughput screening method has highlighted the marked antioxidant activity of some pulvinic acid derivatives (PADs) towards oxidation of thymidine, under ? and UV irradiation, and Fenton-like conditions. Here, we report the synthesis of a series of new hydrophilic PADs and the evaluation of their radioprotective efficacy in cell culture. Using a cell-based fluorescent assay, we show that some of these compounds have a pronounced ability to prevent cell death caused by radiation and to allow the subsequent resumption of proliferation. Thus, PADs may be considered as a novel class of radioprotective agents. (authors)

2011-01-01

250

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

2013-01-29

251

Efficient synthesis of anacardic acid analogues and their antibacterial activities.  

UK PubMed Central (United Kingdom)

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.

Mamidyala SK; Ramu S; Huang JX; Robertson AA; Cooper MA

2013-03-01

252

Single-layered porous silica films on polyethylene terephthalate substrates for antireflection coatings  

International Nuclear Information System (INIS)

Single-layered porous silica films were prepared on polyethylene terephthalate (PET) substrates as antireflection coatings for efficient, large-scale flexible optoelectronic devices. Cetyltrimethylammonium bromide (CTAB)-templated synthesis was employed to form porous silica films. Without using high temperature treatment, CTAB was removed by washing in water to create a porous structure in the films. To spin-coat on PET substrates, contact angle between silica sol and PET surface was measured to optimize the molar ratio of the solution. Pore size and surface sharpness were estimated using atomic force microscope data. The average reflectance of as-prepared AR coatings on PET substrates was ? 2%.

2011-03-31

253

Kinetic regularities and mechanism of electrochemical synthesis of tellurium hydride in the solutions of sulfuric acid  

International Nuclear Information System (INIS)

Results of investigation into kinetics and mechanism of tellurium hydride electrochemical synthesis in different concentration sulfuric acid solutions using partial polarization curve technique are presented. Dependence of mechanism of tellurium cathode dissolution on acid concentration is determined.

1991-01-01

254

Caffeine and uric acid mediate glutathione synthesis for neuroprotection.  

UK PubMed Central (United Kingdom)

Several lines of epidemiological studies have indicated that caffeine consumption and plasma uric acid (UA) level were negatively correlated with the incidence of some neurodegenerative diseases. We report here a novel mechanism by which these purine derivatives increase neuronal glutathione (GSH) synthesis. Intraperitoneal injection of caffeine or UA into male C57BL/6 mice significantly increased total GSH levels in the hippocampus. Neither SCH58261, an adenosine A2A receptor antagonist, nor rolipram, a phosphodiesterase-4 inhibitor, increased GSH levels. Pretreatment with allopurinol, a drug to inhibit UA production, did not change the GSH level in the caffeine-treated mice. Hippocampal CA1 pyramidal neurons treated with caffeine or UA were resistant to oxidant exposure in the slice culture experiments. In experiments with the SH-SY5Y cell line, cysteine uptake was sodium-dependent and pretreatment with caffeine or UA increased cysteine uptake significantly as compared with the control conditions. Slice culture experiments using the hippocampus also showed increased cysteine and GSH contents after the treatment with caffeine or UA. Immunohistochemical analysis showed increased GSH levels in the hippocampal excitatory amino acid carrier-1 (EAAC1)-positive neurons of mice treated with caffeine or UA. These findings suggest that purine derivatives caffeine and UA induce neuronal GSH synthesis by promoting cysteine uptake, leading to neuroprotection.

Aoyama K; Matsumura N; Watabe M; Wang F; Kikuchi-Utsumi K; Nakaki T

2011-05-01

255

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.

1989-01-01

256

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

257

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

Directory of Open Access Journals (Sweden)

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

Nadia Farhana Adnan; Nor Asikin Mohamad Nordin; Noraini Hamzah; Mohd Ambar Yarmo

2011-01-01

258

Regulation of bile acid synthesis in rat hepatocyte monolayer cultures  

Energy Technology Data Exchange (ETDEWEB)

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

Kubaska, W.M.

1986-01-01

259

Isonicotinic acid hydrazide induced changes and inhibition in mycolic acid synthesis in Nocardia and related taxa.  

Science.gov (United States)

The mycolic acid compositions of Nocardia rubra and related bacteria grown in media containing different concentrations of antituberculous isonicotinic acid hydrazide (INH) were determined in detail by gas chromatography-mass spectrometry. On the basis of molecular species composition, average carbon numbers of mycolic acids were calculated. In Nocardia rubra, N. lutea and Rhodococcus rhodochrous IFO-13161, the ratio of mycolic to non-mycolic fatty acids and the average carbon numbers of mycolic acids were decreased at the INH concentrations of higher than 1 microgram/ml, paralleling with the significant inhibition of growth. In above three species the synthesis of longer chain mycolic acids (longer than C44 or C46 ) was inhibited more significantly than shorter homologues such as C38 or C40 . In contrast, neither growth inhibition nor change in corynomycolic acid composition was observed in Corynebacteria xerosis and Rhodococcus rhodochrous IFO-13165 at the concentration region of INH up to 100 micrograms/ml. The direct mass fragmentographic analysis of the trimethylsilylated (TMS) derivatives of mycolic acid methyl esters, monitoring [M-15] ions of individual molecular species, revealed that the chain shortening of total mycolic acid molecule by INH occurred more greatly in more highly unsaturated subclasses than in less unsaturated subclasses. Furthermore, mass fragmentographic analysis, monitoring fragment ions (A) and (B), due to straight chain and branched chain alkyl units, respectively, demonstrated the inhibition of mycolic acids was not attributed to the shortening of alpha-alkyl chain, but to the inhibition of chain elongation of C28 to C32 straight chain meromycolic acids. It was also indicated the amounts of trehalose mono- and di- mycolate (cord factor) decreased significantly with the addition of INH (1 to 20 micrograms/ml) in the above strains. From the results obtained above, INH appeared to inhibit the synthesis of mycolic acids longer than C44 or C46 specifically by inhibiting chain elongation or desaturation of precursor long chain fatty acids longer than C28 or C30. PMID:6428369

Tomiyasu, I; Yano, I

1984-04-01

260

Production process of bis-beta-hydroxyethyl terephthalate and purified bis-beta-hydroxyethyl terephthalate  

UK PubMed Central (United Kingdom)

Bis-beta-hydroxyethyl terephthalate having an optical density measured in a 10 wt% methanol solution at a measurement wavelength of 380 nm and a cell optical path length of 10 mm of 0.000 to 0.006. The present invention makes it clear that purified BHET having an optical density of 0.006 or less provides high-quality PET having excellent purity, whiteness and transparency.

INADA SHUJI; SATO KIKUCHI

 
 
 
 
261

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

UK PubMed Central (United Kingdom)

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.

Liu L; Braun M; Gebhardt G; Weuster-Botz D; Gross R; Schmid RD

2013-01-01

262

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

2012-08-17

263

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

Directory of Open Access Journals (Sweden)

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

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

2012-01-01

264

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

Directory of Open Access Journals (Sweden)

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

Lei Anping; Chen Huan; Shen Guoming; Hu Zhangli; Chen Lei; Wang Jiangxin

2012-01-01

265

Synthesis and biological effects of some kynurenic acid analogs.  

Science.gov (United States)

The overactivation of excitatory amino acid receptors plays a key role in the pathomechanism of several neurodegenerative disorders and in ischemic and post-ischemic events. Kynurenic acid (KYNA) is an endogenous product of the tryptophan metabolism and, as a broad-spectrum antagonist of excitatory amino acid receptors, may serve as a protective agent in neurological disorders. The use of KYNA is excluded, however, because it hardly crosses the blood-brain barrier. Accordingly, new KYNA analogs which can readily cross this barrier and exert their complex anti-excitatory activity are generally needed. During the past 6 years, we have developed several KYNA derivatives, among others KYNA amides. These new analogs included one, N-(2-N,N-dimethylaminoethyl)-4-oxo-1H-quinoline-2-carboxamide hydrochloride (KYNA-1), that has proved to be neuroprotective in several models. This paper reports on the synthesis of 10 new KYNA amides (KYNA-1-KYNA-10) and on the effectiveness of these molecules as inhibitors of excitatory synaptic transmission in the CA1 region of the hippocampus. The molecular structure and functional effects of KYNA-1 are compared with those of other KYNA amides. Behavioral studies with these KYNA amides demonstrated that they do not exert significant nonspecific general side-effects. KYNA-1 may therefore be considered a promising candidate for clinical studies. PMID:22079867

Nagy, K; Plangár, I; Tuka, B; Gellért, L; Varga, D; Demeter, I; Farkas, T; Kis, Zs; Marosi, M; Zádori, D; Klivényi, P; Fülöp, F; Szatmári, I; Vécsei, L; Toldi, J

2011-10-18

266

Synthesis and biological effects of some kynurenic acid analogs.  

UK PubMed Central (United Kingdom)

The overactivation of excitatory amino acid receptors plays a key role in the pathomechanism of several neurodegenerative disorders and in ischemic and post-ischemic events. Kynurenic acid (KYNA) is an endogenous product of the tryptophan metabolism and, as a broad-spectrum antagonist of excitatory amino acid receptors, may serve as a protective agent in neurological disorders. The use of KYNA is excluded, however, because it hardly crosses the blood-brain barrier. Accordingly, new KYNA analogs which can readily cross this barrier and exert their complex anti-excitatory activity are generally needed. During the past 6 years, we have developed several KYNA derivatives, among others KYNA amides. These new analogs included one, N-(2-N,N-dimethylaminoethyl)-4-oxo-1H-quinoline-2-carboxamide hydrochloride (KYNA-1), that has proved to be neuroprotective in several models. This paper reports on the synthesis of 10 new KYNA amides (KYNA-1-KYNA-10) and on the effectiveness of these molecules as inhibitors of excitatory synaptic transmission in the CA1 region of the hippocampus. The molecular structure and functional effects of KYNA-1 are compared with those of other KYNA amides. Behavioral studies with these KYNA amides demonstrated that they do not exert significant nonspecific general side-effects. KYNA-1 may therefore be considered a promising candidate for clinical studies.

Nagy K; Plangár I; Tuka B; Gellért L; Varga D; Demeter I; Farkas T; Kis Z; Marosi M; Zádori D; Klivényi P; Fülöp F; Szatmári I; Vécsei L; Toldi J

2011-12-01

267

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

Energy Technology Data Exchange (ETDEWEB)

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

268

SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF AMIDE DERIVATIVES FROM ACRYLOPIMARIC ACID  

Directory of Open Access Journals (Sweden)

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,; Xiaoping Rao,; Shibin Shang,; Yanqing Gao; , Jie Song

2012-01-01

269

Kinetic resolution and stereoselective synthesis of 3-substituted aspartic acids by using engineered methylaspartate ammonia lyases.  

UK PubMed Central (United Kingdom)

Enzymatic amino acid synthesis: Kinetic resolution and asymmetric synthesis of various valuable 3-substituted aspartic acids, which were obtained in fair to good yields with diastereomeric ratio values of up to >98:2 and enantiomeric excess values of up to >99?%, by using engineered methylaspartate ammonia lyases are described. These biocatalytic methodologies for the selective preparation of aspartic acid derivatives appear to be attractive alternatives for existing chemical methods.

Raj H; Szymanski W; de Villiers J; Puthan Veetil V; Quax WJ; Shimamoto K; Janssen DB; Feringa BL; Poelarends GJ

2013-08-01

270

78 FR 52500 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China: Notice of...  

Science.gov (United States)

...Trade Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip...2\\ See Polyethylene Terephthalate Film, Sheet, and Strip...1332 (Ct. Int'l Trade 2013); Polyethylene Terephthalate Film, Sheet, and...

2013-08-23

271

76 FR 22867 - Polyethylene Terephthalate Film, Sheet, and Strip From the United Arab Emirates: Final Results of...  

Science.gov (United States)

...Trade Administration [A-520-803] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film (PET Film) from...following events have taken place. See Polyethylene Terephthalate Film, Sheet, and...

2011-04-25

272

78 FR 29700 - Polyethylene Terephthalate Film, Sheet, and Strip From the United Arab Emirates: Final Results of...  

Science.gov (United States)

...Trade Administration [A-520-803] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film (PET Film) from...1\\ See Polyethylene Terephthalate Film, Sheet, and...

2013-05-21

273

76 FR 1135 - Polyethylene Terephthalate Film, Sheet, and Strip From the Republic of Korea: Final Results of...  

Science.gov (United States)

...Trade Administration [A-580-807] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and strip...review of the antidumping duty order on polyethylene terephthalate film, sheet, and...

2011-01-07

274

75 FR 70901 - Polyethylene Terephthalate Film, Sheet, and Strip From the Republic of Korea: Final Results of...  

Science.gov (United States)

...Trade Administration [A-580-807] Polyethylene Terephthalate Film, Sheet, and Strip...review of the antidumping order on polyethylene terephthalate film, sheet and strip...the Republic of Korea (Korea). See Polyethylene Terephthalate Film, Sheet, and...

2010-11-19

275

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

Directory of Open Access Journals (Sweden)

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.; Laskaridis, K.; Koliokota, E.; Sagredos, A.

2011-01-01

276

Synthesis and pharmacokinetic profile of rhein- boswellic acid conjugate.  

UK PubMed Central (United Kingdom)

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.

Suneela D; Dipmala P

2012-12-01

277

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

2012-10-11

278

Enzymatic synthesis and application of fatty acid ascorbyl esters  

Directory of Open Access Journals (Sweden)

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.; Carevi? Milica B.; Mihailovi? Mladen D.; Kneževi?-Jugovi? Zorica D.; Petrovi? Slobodan D.; Bezbradica Dejan I.

2013-01-01

279

Tissue fatty acid profiles can be used to quantify endogenous rumenic acid synthesis in lambs.  

UK PubMed Central (United Kingdom)

Proportions of vaccenic (trans-11 18:1) and rumenic (cis-9, trans-11 18:2) acids in mesenteric adipose, subcutaneous adipose, and longissimus muscle tissue lipids from lambs fed varying proportions of forages and concentrates were used to develop a mathematical model to predict exogenous and endogenous contributions to rumenic acid (RA) in the several tissues. From the model, we were able to estimate the proportion of absorbed RA, the proportion of vaccenic acid (VA) desaturated, the original proportion of VA in the tissue (before desaturation), and finally the proportion of RA synthesized endogenously. Estimates of endogenous RA were in the range of published data estimated by independent procedures. An independent data set of VA and RA in milk fat was used to challenge the model. Predictions were concordant with observations, although estimates of endogenous RA synthesis were lower than previous reports. Changing the amount of exogenous RA through manipulation of the diet influenced desaturation of VA inversely, so that endogenous RA synthesis was decreased when exogenous supply was increased (r = -0.80). The model should be challenged with data from human and nonruminant, as well as ruminant studies.

Palmquist DL; St-Pierre N; McClure KE

2004-09-01

280

An improved synthesis of 'octa-acid' deep-cavity cavitand.  

UK PubMed Central (United Kingdom)

An improved synthesis of a water-soluble deep-cavity cavitand (octa-acid, 1) is presented. Previously (Gibb, C. L. D. & Gibb, B. C., J. Am. Chem. Soc., 2004, 126, 11408-11409) we documented access to host 1 in eight (non-linear) steps starting from resorcinol; a synthesis that required four steps involving chromatographic purification. Here we reveal a modified synthesis of host 1. Consisting of seven (non-linear) steps, this new synthesis involves only one chromatographic step, and avoids a minor impurity observed in the original approach. This improved synthesis will therefore be useful for the laboratories that are investigating the properties of these types of host.

Liu S; Whisenhunt-Ioup SE; Gibb CL; Gibb BC

2011-01-01

 
 
 
 
281

Inhibition of carbonate synthesis in acidic oceans on early Mars.  

UK PubMed Central (United Kingdom)

Several lines of evidence have recently reinforced the hypothesis that an ocean existed on early Mars. Carbonates are accordingly expected to have formed from oceanic sedimentation of carbon dioxide from the ancient martian atmosphere. But spectral imaging of the martian surface has revealed the presence of only a small amount of carbonate, widely distributed in the martian dust. Here we examine the feasibility of carbonate synthesis in ancient martian oceans using aqueous equilibrium calculations. We show that partial pressures of atmospheric carbon dioxide in the range 0.8-4 bar, in the presence of up to 13.5 mM sulphate and 0.8 mM iron in sea water, result in an acidic oceanic environment with a pH of less than 6.2. This precludes the formation of siderite, usually expected to be the first major carbonate mineral to precipitate. We conclude that extensive interaction between an atmosphere dominated by carbon dioxide and a lasting sulphate- and iron-enriched acidic ocean on early Mars is a plausible explanation for the observed absence of carbonates.

Fairén AG; Fernández-Remolar D; Dohm JM; Baker VR; Amils R

2004-09-01

282

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

International Nuclear Information System (INIS)

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.

2011-05-31

283

Activities of Heterogeneous Acid-Base Catalysts for Fragrances Synthesis: A Review  

Directory of Open Access Journals (Sweden)

Full Text Available This paper reviews various types of heterogeneous acid-base catalysts for fragrances preparation. Catalytic activities of various types of heterogeneous acid and base catalysts in fragrances preparation, i.e. non-zeolitic, zeolitic, and mesoporous molecular sieves have been reported. Generally, heterogeneous acid catalysts are commonly used in fragrance synthesis as compared to heterogeneous base catalysts. Heteropoly acids and hydrotalcites type catalysts are widely used as heterogeneous acid and base catalysts, respectively. © 2013 BCREC UNDIP. All rights reserved

Hartati, Hartati; Santoso, Mardi; Triwahyono, Sugeng; Prasetyoko, Didik

2013-01-01

284

Determination of potential migrants from commercial amber polyethylene terephthalate bottle wall  

Energy Technology Data Exchange (ETDEWEB)

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

Kim, H.; Gilbert, S.G.; Johnson, J.B. (Rutgers Univ., New Brunswick, NJ (USA))

1990-02-01

285

Magnesium Starvation of Aerobacter aerogenes II. Rates of Nucleic Acid Synthesis and Methods for Their Measurement  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The rates of synthesis of Aerobacter aerogenes nucleic acids were estimated during incubation of the bacteria in a Mg++-free medium. Deoxyribonucleic acid (DNA) synthesized during Mg++ starvation, or in the preceding exponential growth, remained acid-precipitable for 2.5 hr before breaking down to a...

Kennell, David; Kotoulas, Angeliki

286

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

International Nuclear Information System (INIS)

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

1986-01-01

287

Nalidixic Acid and Macromolecular Metabolism in Tetrahymena pyriformis: Effects on Protein Synthesis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A study on the effect of nalidixic acid on macromolecular metabolism, particularly of protein, in Tetrahymena pyriformis was performed. It was shown that the compound is a potent inhibitor of deoxyribonucleic acid, ribonucleic acid, and protein synthesis for this organism. A conspicuous breakdown of...

de Castro, J. F.; Carvalho, J. F. O.; Moussatché, N.; de Castro, F. T.

288

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

DEFF Research Database (Denmark)

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

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

1972-01-01

289

Synthesis of novel acid electrolytes for phosphoric acid fuel cells. Final report, May 1985-October 1988  

Energy Technology Data Exchange (ETDEWEB)

Construction of a 40-millimole-per-hour-scale aerosol direct-fluorination reactor was completed June 26, 1986. F-Methyl F-4-methoxybutanoate and F-4-methoxybutanoyl fluoride were synthesized by aerosol direct fluorination of methyl 4-methoxybutanoate. Basic hydrolysis of the perfluorinated derivatives produce sodium F-4-methoxybutanoate which was pyrolyzed to F-3-methoxy-1-propene. Purification and shipment of 33 grams of F-3-methoxy-1-propene followed. Syntheses by analogous methods allowed production and shipment of 5 grams of F-3-ethoxy-1-propene, 18 grams of F-3-(2-methoxy.ethoxy)-1-propene, and 37 grams of F-3,3-dimethyl-1-butene. Eighteen grams of F-2,2-dimethyl-1-chloropropane was produced directly and shipped. As suggested by other contractors, 5 grams of F-3-methoxy-1-iodopropane, and 5 grams of F-3-(2-methoxy.ethoxy)-1-iodopropane were produced by converting the respective precursor acid sodium salts produced for olefin synthesis to the silver salts and pyrolyzing them with iodine. Each of these compounds was prepared for the first time by the aerosol fluorination process during the course of the contract. These samples were provided to other GRI contractors for synthesis of perfluorinated sulfur(VI) and phosphorous(V) acids.

Adcock, J.L.

1988-11-01

290

78 FR 60311 - Polyethylene Terephthalate Film, Sheet, and Strip From Brazil, China, and the United Arab...  

Science.gov (United States)

...Investigation Nos. 731-TA-1131, 1132, and 1134 (Review)] Polyethylene Terephthalate Film, Sheet, and Strip From Brazil, China...determine whether revocation of the antidumping duty order on polyethylene terephthalate (``PET'') film, sheet, and strip...

2013-10-01

291

76 FR 42113 - Polyethylene Terephthalate Film, Sheet, and Strip From the People's Republic of China: Extension...  

Science.gov (United States)

...COMMERCE International Trade Administration [A-570-924] Polyethylene Terephthalate Film, Sheet, and Strip From the People's...for the preliminary results of the administrative review of polyethylene terephthalate film, sheet, and strip (``PET...

2011-07-18

292

78 FR 42105 - Polyethylene Terephthalate Film, Sheet, and Strip From India and Taiwan; Notice of Commission...  

Science.gov (United States)

...701-TA-415 and 731-TA-933-934 (Second Review)] Polyethylene Terephthalate Film, Sheet, and Strip From India and Taiwan...determine whether revocation of the countervailing duty order on polyethylene terephthalate film, sheet, and strip (``PET''...

2013-07-15

293

Regulation of Polyglutamic Acid Synthesis by Glutamate in Bacillus licheniformis and Bacillus subtilis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthesis of polyglutamic acid (PGA) was repressed by exogenous glutamate in strains of Bacillus licheniformis but not in strains of Bacillus subtilis, indicating a clear difference in the regulation of synthesis of capsular slime in these two species. Although extracellular ?-glutamyltranspepti...

Kambourova, Margarita; Tangney, Martin; Priest, Fergus G.

294

Rifampin Susceptibility of Ribonucleic Acid Synthesis in a Fragile Saccharomyces cerevisiae Mutant  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ribonucleic acid (RNA) synthesis in the sorbitol-dependent, fragile yeast mutant VY1160 (Venkov et al., 1974) is rapidly inhibited by rifampin. The growth of the mutant cells and protein synthesis are more slowly affected by the antibiotic, apparently as secondary phenomena. Lower doses of rifampin ...

Venkov, P. V.; Milchev, G. I.; Hadjiolov, A. A.

295

Solid phase synthesis of peptide hydroxamic acids on poly(ethylene glycol)-based support.  

UK PubMed Central (United Kingdom)

A novel resin designed for solid-phase synthesis of peptide hydroxamic acids (PHA) combining the trityl linker with poly(ethylene glycol)-based support, ChemMatrix® type, is described. The synthesis of PHA can be performed according to a standard protocol, providing products in excellent purity and reasonable yields.

Cal M; Jaremko M; Jaremko ?; Stefanowicz P

2013-01-01

296

Synthesis and cytotoxic activity of new betulin and betulinic acid esters with conjugated linoleic acid (CLA).  

UK PubMed Central (United Kingdom)

The synthesis of new ester derivatives of betulin (3a-c) and betulinic acid (4) with conjugated linoleic acid isomers (CLA; in a mixture of 43.4% 9c, 11t; 49.5% 10t, 12c; 7.1% other isomers) is presented. Esterification was carried out with N,N'-dicyclohexylcarbodiimide (DCC) as the coupling agent in the presence of 4-dimethylamino-pyridine (DMAP) in dichloromethane (or pyridine). The in vitro cytotoxic effect of betulin (1), betulinic acid (2), a mixture of CLA isomers and their derivatives (3a-c, 4) was examined using the MTT assay against four cancer cell lines (P388, CEM/C2, CCRF/CEM and HL-60) and the SRB assay on the HT-29 cell line. Ester 4 was the most active among the esters synthesized against the CEM/C2 cell line with an ID50 value 16.9 +/- 6.5 microg/mL. Betulin (1), betulinic acid (2) and CLA were the most active agents against the cancer cell lines studied.

Tubek B; Mitu?a P; Niezgoda N; Kempi?ska K; Wietrzyk J; Wawrze?czyk C

2013-04-01

297

Synthesis and cytotoxic activity of new betulin and betulinic acid esters with conjugated linoleic acid (CLA).  

Science.gov (United States)

The synthesis of new ester derivatives of betulin (3a-c) and betulinic acid (4) with conjugated linoleic acid isomers (CLA; in a mixture of 43.4% 9c, 11t; 49.5% 10t, 12c; 7.1% other isomers) is presented. Esterification was carried out with N,N'-dicyclohexylcarbodiimide (DCC) as the coupling agent in the presence of 4-dimethylamino-pyridine (DMAP) in dichloromethane (or pyridine). The in vitro cytotoxic effect of betulin (1), betulinic acid (2), a mixture of CLA isomers and their derivatives (3a-c, 4) was examined using the MTT assay against four cancer cell lines (P388, CEM/C2, CCRF/CEM and HL-60) and the SRB assay on the HT-29 cell line. Ester 4 was the most active among the esters synthesized against the CEM/C2 cell line with an ID50 value 16.9 +/- 6.5 microg/mL. Betulin (1), betulinic acid (2) and CLA were the most active agents against the cancer cell lines studied. PMID:23738445

Tubek, Barbara; Mitu?a, Pawe?; Niezgoda, Natalia; Kempi?ska, Katarzyna; Wietrzyk, Joanna; Wawrze?czyk, Czes?aw

2013-04-01

298

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

Science.gov (United States)

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

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

2012-07-01

299

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

International Nuclear Information System (INIS)

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

1992-01-01

300

Stereoselective synthesis of cyclic amino acids via asymmetric phase-transfer catalytic alkylation.  

UK PubMed Central (United Kingdom)

An asymmetric synthesis of cyclic amino acids having piperidine and azepane core structures was realized starting from readily available glycine and alanine esters by combination of phase-transfer catalyzed asymmetric alkylation and subsequent reductive amination.

Kano T; Kumano T; Sakamoto R; Maruoka K

2013-01-01

 
 
 
 
301

Ultrasound-assisted synthesis of aliphatic acid esters at room temperature.  

UK PubMed Central (United Kingdom)

This work describes the ultrasound-assisted synthesis of saturated aliphatic esters from synthetic aliphatic acids and either methanol or ethanol. The products were isolated in good yields after short reaction times under mild conditions.

Hobuss CB; Venzke D; Pacheco BS; Souza AO; Santos MA; Moura S; Quina FH; Fiametti KG; Vladimir Oliveira J; Pereira CM

2012-05-01

302

Brønsted acid assisted activation of imide carbonyl group: regioselective synthesis of isoindoloisoquinolinone alkaloid (±)-nuevamine.  

Science.gov (United States)

Activation of imide carbonyl group with trifluoromethanesulfonic acid facilitates the intramolecular cyclization of phenethylphthalimides to give a fused isoindoloisoquinolinone skeleton. The first one pot regioselective synthesis of isoindoloisoquinolinone alkaloid (±)-nuevamine has been successfully executed using this methodology. PMID:21938306

Selvakumar, Jayaraman; Ramanathan, Chinnasamy Ramaraj

2011-09-22

303

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

Directory of Open Access Journals (Sweden)

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

Sunita B. Shinde; Sunil U.Tekale; Sushma S. Kauthale; Satish U. Deshmukh; Rajendra P. Marathe; Rajesh B. Nawale; Vinayak S. Sonekar; Vinod V. Thorat; Rajendra P. Pawar

2011-01-01

304

Intramolecular hydroalkoxylation in Bronsted acidic ionic liquids and its application to the synthesis of (±)-centrolobine.  

UK PubMed Central (United Kingdom)

The SO(3)H-tethered imidazolium and triazolium salts, nonvolatile and recyclable Brønsted acidic ionic liquids, efficiently mediate intramolecular hydroalkoxylations of alkenyl alcohols. They have been successfully employed in the synthesis of (±)-centrolobine.

Jeong Y; Kim DY; Choi Y; Ryu JS

2011-01-01

305

[3,3]Paracyclophanes as planar chiral scaffolds for the synthesis of new phosphoric acids.  

UK PubMed Central (United Kingdom)

Cyclic phosphoric acids displaying planar chiral paracyclophane structures, which include a 1,1'-ferrocenediyl unit, have been designed as a new class of chiral organocatalysts. Their synthesis, optical resolution, structural characterization and preliminary catalytic tests are reported.

Stemper J; Isaac K; Duret V; Retailleau P; Voituriez A; Betzer JF; Marinetti A

2013-07-01

306

Copper-Catalyzed Formic Acid Synthesis from CO(2) with Hydrosilanes and H(2)O.  

UK PubMed Central (United Kingdom)

A copper-catalyzed formic acid synthesis from CO(2) with hydrosilanes has been accomplished. The Cu(OAc)(2)·H(2)O-1,2-bis(diphenylphosphino)benzene system is highly effective for the formic acid synthesis under 1 atm of CO(2). The TON value approached 8100 in 6 h. The reaction pathway was revealed by in situ NMR analysis and isotopic experiments.

Motokura K; Kashiwame D; Miyaji A; Baba T

2012-04-01

307

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.

Baowei Hu; Chunqing Li; Sheng-Xian Zhao; Lin-Mei Rong; Shao-Qin Lv; Xuezheng Liang; Chenze Qi

2010-01-01

308

A one-pot synthesis of (±)-(ring 13C6)-mandelic acid  

International Nuclear Information System (INIS)

[en] A one-pot synthesis of (ring 13C6)-mandelic acid is reported. [Ring 13C6]-benzaldehyde was cyanosilylated with trimethylsilyl cyanide (TMSCN)/ZnI2. The resulting cyanosilylated adduct was hydrolyzed with concentrated hydrochloric acid without purification. The workup involves evaporation to dryness and extraction of the (ring 13C6)-mandelic acid with hot benzene. After one crystallization, the synthesis produced an overall yield of 65% of (ring 13C6)-mandelic acid that was about 98% pure by HPLC with UV detection. (Author)

1993-01-01

309

Highly efficient procedure for the synthesis of fructone fragrance using a novel carbon based acid.  

UK PubMed Central (United Kingdom)

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 beta-keto esters make this novel carbon based acid one of the best choices for the reaction.

Hu B; Li C; Zhao SX; Rong LM; Lv SQ; Liang X; Qi C

2010-08-01

310

Mechanism of triclosan inhibition of bacterial fatty acid synthesis.  

UK PubMed Central (United Kingdom)

Triclosan is a broad-spectrum antibacterial agent that inhibits bacterial fatty acid synthesis at the enoyl-acyl carrier protein reductase (FabI) step. Resistance to triclosan in Escherichia coli is acquired through a missense mutation in the fabI gene that leads to the expression of FabI[G93V]. The specific activity and substrate affinities of FabI[G93V] are similar to FabI. Two different binding assays establish that triclosan dramatically increases the affinity of FabI for NAD+. In contrast, triclosan does not increase the binding of NAD+ to FabI[G93V]. The x-ray crystal structure of the FabI-NAD+-triclosan complex confirms that hydrogen bonds and hydrophobic interactions between triclosan and both the protein and the NAD+ cofactor contribute to the formation of a stable ternary complex, with the drug binding at the enoyl substrate site. These data show that the formation of a noncovalent "bi-substrate" complex accounts for the effectiveness of triclosan as a FabI inhibitor and illustrates that mutations in the FabI active site that interfere with the formation of a stable FabI-NAD+-triclosan ternary complex acquire resistance to the drug.

Heath RJ; Rubin JR; Holland DR; Zhang E; Snow ME; Rock CO

1999-04-01

311

Distribution, synthesis, and absorption of kynurenic acid in plants.  

Science.gov (United States)

Kynurenic acid (KYNA) is an endogenous antagonist of the ionotropic glutamate receptors and the ?7 nicotinic acetylcholine receptor as well as an agonist of the G-protein-coupled receptor GPR35. In this study, KYNA distribution and synthesis in plants as well as its absorption was researched. KYNA level was determined by means of the high-performance liquid chromatography with fluorescence detection. KYNA was found in leaves, flowers, and roots of tested medicinal herbs: dandelion (Taraxacum officinale), common nettle (Urtica dioica), and greater celandine (Chelidoniummajus). The highest concentration of this compound was detected in leaves of dandelion--a mean value of 0.49 µg/g wet weight. It was shown that KYNA can be synthesized enzymatically in plants from its precursor, L-kynurenine, or absorbed by plants from the soil. Finally, the content of KYNA was investigated in 21 herbal tablets, herbal tea, herbs in sachets, and single herbs in bags. The highest content of KYNA in a maximum daily dose of herbal medicines appeared in St. John's wort--33.75 µg (tablets) or 32.60 µg (sachets). The pharmacological properties of KYNA and its presence in high concentrations in medicinal herbs may suggest that it possesses therapeutic potential, especially in the digestive system and should be considered a new valuable dietary supplement. PMID:21157681

Turski, Michal P; Turska, Monika; Zgrajka, Wojciech; Bartnik, Magdalena; Kocki, Tomasz; Turski, Waldemar A

2010-12-14

312

Synthesis of carboranyl amino acids, hydantoins, and barbiturates  

Energy Technology Data Exchange (ETDEWEB)

The syntheses of three novel boronated hydantoins, 5-(o-carboran-1-ylmethyl)hydantoin, 14, the tetraphenylphosphonium salt of 7-(hydantoin-5-ylmethyl)dodecahydro-7,8-dicarba-nido-undecaborate, 15, 5-(o-carboran-1-ylmethyl)-2-thiohydantoin, 16, and two new barbiturates, 5,5-bis(but-2-ynyl)barbiturate, 18, and 5,5-bis[(2-methyl-0-carboran-1-yl)methyl]barbiturate, 20, are described. Hydantoins 14-16 were synthesized from o-carboranylalanine (Car, 13). The detailed synthesis of Car and two other carborane-containing amino acids, O-(o-carboran-1-ylmethyl)tyrosine (CBT, 5a) and p-(o-carboran-1-yl)phenylalanine (CBPA, 5b), presented earlier as a communication, {sup 16} are also described. Hydantoin 14 and barbiturates 18 and 20 were tested for their potential anticonvulsant activity. Initial qualitative screening showed moderate activities for hydantoin 14 and barbiturate 18. Barbiturate 20 had no activity. Compound 14 appeared to be nontoxic at doses of 300 mg/kg (mice, ip) and 50 mg/kg (rats, oral). However, 18 was very toxic under similar conditions.

Wyzlic, I.M.; Tjarks, W.; Soloway, A.H. [Ohio State Univ., Columbus, OH (United States)] [and others

1996-07-31

313

Synthesis of carboranyl amino acids, hydantoins, and barbiturates  

International Nuclear Information System (INIS)

The syntheses of three novel boronated hydantoins, 5-(o-carboran-1-ylmethyl)hydantoin, 14, the tetraphenylphosphonium salt of 7-(hydantoin-5-ylmethyl)dodecahydro-7,8-dicarba-nido-undecaborate, 15, 5-(o-carboran-1-ylmethyl)-2-thiohydantoin, 16, and two new barbiturates, 5,5-bis(but-2-ynyl)barbiturate, 18, and 5,5-bis[(2-methyl-0-carboran-1-yl)methyl]barbiturate, 20, are described. Hydantoins 14-16 were synthesized from o-carboranylalanine (Car, 13). The detailed synthesis of Car and two other carborane-containing amino acids, O-(o-carboran-1-ylmethyl)tyrosine (CBT, 5a) and p-(o-carboran-1-yl)phenylalanine (CBPA, 5b), presented earlier as a communication, 16 are also described. Hydantoin 14 and barbiturates 18 and 20 were tested for their potential anticonvulsant activity. Initial qualitative screening showed moderate activities for hydantoin 14 and barbiturate 18. Barbiturate 20 had no activity. Compound 14 appeared to be nontoxic at doses of 300 mg/kg (mice, ip) and 50 mg/kg (rats, oral). However, 18 was very toxic under similar conditions

1996-07-31

314

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

Energy Technology Data Exchange (ETDEWEB)

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

Hugenberg, S.T.; Myers, S.L.; Brandt, K.D.

1989-04-01

315

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

International Nuclear Information System (INIS)

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

1989-01-01

316

A Practical and Convenient Protocol for the Synthesis of (E)-?,?-Unsaturated Acids.  

UK PubMed Central (United Kingdom)

?,?-Unsaturated acids are very useful and versatile reagents in organic synthesis. A novel, practical, and convenient catalytic protocol comprising FeCl3·6H2O (0.5 mol %) and H2O (1 equiv) in CH3NO2 is described for the rapid synthesis of ?,?-unsaturated acids with high E-stereoselectivity under both microwave and conventional heating conditions with high TON and TOF values. This powerful approach efficiently demonstrated the utility of biomass derived aldehydes to build chemical agents used as fuel additives. The method proved to be scalable to gram scale synthesis.

Mohite AR; Bhat RG

2013-09-01

317

A practical and convenient protocol for the synthesis of (E)-?,?-unsaturated acids.  

Science.gov (United States)

?,?-Unsaturated acids are very useful and versatile reagents in organic synthesis. A novel, practical, and convenient catalytic protocol comprising FeCl3·6H2O (0.5 mol %) and H2O (1 equiv) in CH3NO2 is described for the rapid synthesis of ?,?-unsaturated acids with high E-stereoselectivity under both microwave and conventional heating conditions with high TON and TOF values. This powerful approach efficiently demonstrated the utility of biomass derived aldehydes to build chemical agents used as fuel additives. The method proved to be scalable to gram scale synthesis. PMID:23962223

Mohite, Amar R; Bhat, Ramakrishna G

2013-08-20

318

METHOD OF PROMOTING SYNTHESIS OF DOCOSAHEXAENOIC ACID BY ADDING CARBON SOURCE  

UK PubMed Central (United Kingdom)

Provided is a method of promoting synthesis of docosahexaenoic acid by a marine microorganism, which includes the addition of any one or any combinations of acetic acid, citric acid and simvastatin in an initial fermentation medium, or the supplement of acetic acid in the fermentation process. The said marine microorganism is selected from Thraustochytrid sp., Schizochytrium sp. and Crypthecodinium sp.. The method is simple, environmentally friendly, and cost effective.

HUANG HE; WEI PING; JI XIAOJUN; REN LUJING; XIAO AIHUA; TONG QIANQIAN

319

Synthesis of L-glutamic acid stereospecifically labeled at C-4 with deuterium  

International Nuclear Information System (INIS)

[en] 4-[2H2]-L-glutamic acid was prepared in excellent yield by enzymatic reductive amination of 4-[2H2]-2-ketoglutaric acid. The synthesis of stereospecifically deuterated (4 R) and (4 S)-[4-2H2]-L-glutamic acids from (2 RS, 4 S) and (2 RS, 4 R)-4-hydroxyglutamic acids, involving a reduction step by sodium cyanoboro-deuteride, was shown to proceed with 75% inversion of configuration. (author)

1985-01-01

320

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

 
 
 
 
321

Asymmetric synthesis including enzymatic catalysis of 11C and 13N labelled amino acids  

International Nuclear Information System (INIS)

Use of asymmetric synthesis in production of 11C- and 13N-labelled amino acids has been shown to be a useful approach in order to prepare amino acids routinely for PET-studies. Such PET-studies are focused either on problems related to amino acid transport, protein synthesis rate or the turnover of neurotransmitters from amino acids. The paper discusses matters regarding synthetic strategies and techniques involving production of precursors, labelled intermediates and main reaction sequences. In synthesis using the short-lived ?+-emitters like 11C and 13N with T1/2 of 20.3 and 10.0 min respectively, many special aspects have to be considered. The use of enzymes as catalysts has shown to be a useful tool in such preparations. The design of the labelled amino acids especially considering the stereochemistry, the position of the label will be addressed since these points are important both with regard to the application of the labelled amino acids as well as to the synthesis itself. In this presentation of the synthesis of labelled amino acids these various aspects are discussed.

1993-01-01

322

Improvement of synthesis method of 6-hydroxy-2-(4'-aminophenyl) benzothiazole  

UK PubMed Central (United Kingdom)

The invention discloses the improvement of a synthesis method of 6-hydroxy-2-(4'-aminophenyl) benzothiazole which is a PET (polyethylene terephthalate) developer 11C-6-OH-BTA (Benzotriazole) precursor of the Alzheimer's disease. In the invention, key steps of demethylation and nitryl reduction are improved hydroiodic acid is used as a reducing agent and a demethylation and nitryl reduction products are obtained by using a one-pot method, thereby the use of boron tribromide and stannous chloride is avoided. The reaction is simple and easy to apply, the raw material is easy to obtain, and the total yield is higher than that reported by literatures.

PEIJI SHI; HAO WANG; RONGXIAN WANG; MINGFEN WU; XIAOLIANG ZHOU

323

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)

[en] 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)

2005-01-01

324

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)

1978-01-01

325

Heat capacity of poly(trimethylene terephthalate)  

Energy Technology Data Exchange (ETDEWEB)

Thermal analysis of poly(trimethylene terephthalate) (PTT) has been carried out using standard differential scanning calorimetry and temperature-modulated differential scanning calorimetry. Heat capacities of the solid and liquid states of semicrystalline PTT are reported from 190 K to 570 K. The semicrystalline PTT has a glass transition temperature of about 331 K. Between 460 K and 480 K, PTT shows an exothermic ordering. The melting endotherm occurs between 480 K and 505 K with an onset temperature of 489.15 K (216 C). The heat of fusion of typical semicrystalline samples is 13.8 kJ/mol. For 100% crystalline PTT the heat of fusion is estimated to be 28--30 kJ/mol. The heat capacity of solid PTT is linked to an approximate group vibrational spectrum, and the Tarasov equation is used to estimate the skeletal vibrational heat capacity ({Theta}{sub 1} = 542 K and {Theta}{sub 3} = 42 K). A comparison of calculation and experimental heat capacities show agreement of better than {+-}2% between 190--300 K. The experimental heat capacity of liquid PTT can be expressed as a linear function of temperature: C{sub p} {sup L}(exp) = 211.6 + 0.434 T J/(K mol) and compares well with estimations from the ATHAS data bank using group contributions of other polymers with the same constituent groups ({+-} 0.5%). The change of heat capacity at T{sub g} of amorphous PTT has been estimated from the heat capacities of liquid and solid to be 86.4 J/(K mol). Knowing C{sub p} of the solid, liquid, and the transition parameters, the thermodynamic functions: enthalpy, entropy and Gibbs function were obtained.

Pyda, M.; Boller, A.; Wunderlich, B. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry]|[Oak Ridge National Lab., TN (United States). Chemical and Analytical Science Div.; Grebowicz, J.; Chuah, H. [Shell Development Co., Houston, TX (United States)

1997-12-01

326

A thermodynamic basis for prebiotic amino acid synthesis and the nature of the first genetic code  

CERN Multimedia

Of the twenty amino acids used in proteins, ten were formed in Miller's atmospheric discharge experiments. The two other major proposed sources of prebiotic amino acid synthesis include formation in hydrothermal vents and delivery to Earth via meteorites. We combine observational and experimental data of amino acid frequencies formed by these diverse mechanisms and show that, regardless of the source, these ten early amino acids can be ranked in order of decreasing abundance in prebiotic contexts. This order can be predicted by thermodynamics. The relative abundances of the early amino acids were most likely reflected in the composition of the first proteins at the time the genetic code originated. The remaining amino acids were incorporated into proteins after pathways for their biochemical synthesis evolved. This is consistent with theories of the evolution of the genetic code by stepwise addition of new amino acids. These are hints that key aspects of early biochemistry may be universal.

Higgs, Paul G

2009-01-01

327

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

2010-01-01

328

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.

GORDANA TASIC; RADOMIR MATOVIC; RADOMIR N. SAICIC

2004-01-01

329

?-Transaminase-catalyzed asymmetric synthesis of unnatural amino acids using isopropylamine as an amino donor.  

UK PubMed Central (United Kingdom)

Isopropylamine is an ideal amino donor for reductive amination of carbonyl compounds by ?-transaminase (?-TA) owing to its cheapness and high volatility of a ketone product. Here we developed asymmetric synthesis of unnatural amino acids via ?-TA-catalyzed amino group transfer between ?-keto acids and isopropylamine.

Park ES; Dong JY; Shin JS

2013-09-01

330

Kinetics of acetic acid synthesis from ethanol over a Cu/SiO2 catalyst  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The dehydrogenation of ethanol via acetaldehyde for the synthesis of acetic acid over a Cu based catalyst in a new process is reported. Specifically, we have studied a Cu on SiO2 catalyst which has shown very high selectivity to acetic acid via acetaldehyde compared to competing condensation routes....

Voss, Bodil; Schjødt, Niels Christian; Grunwaldt, Jan-Dierk; Andersen, Simon Ivar; Woodley, John

331

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

Directory of Open Access Journals (Sweden)

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

Lupea Xenia Alfa; Padure Mirabela

2003-01-01

332

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

International Nuclear Information System (INIS)

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

1987-05-01

333

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1987-05-01

334

Studies on the regulation of fatty acid and cholesterol synthesis in avian liver.  

UK PubMed Central (United Kingdom)

Homogenates of pigeon liver have been incubated with acetate-C(14) in excess. Simultaneously, substrate for glycolysis was provided as glucose-6-phosphate. The incorporation of carbon-14 into cholesterol was maximal at low levels of glycolysis, whereas fatty acid turnover was maximum at higher glycolytic levels. A regulatory mechanism is proposed to explain the differential synthesis of cholesterol and fatty acids.

LAYNE EC; RUDOLPH GG; BESSMAN SP

1960-08-01

335

A Three Step Synthesis of 11-Cycloheptylundecanoic Acid, a Component of the Thermoacidophile Alicyclobacillus cycloheptanicus  

Directory of Open Access Journals (Sweden)

Full Text Available A simple synthesis of the methyl ester of 11-cycloheptylundecanoic acid (1), isolated from the lipid fraction of the thermoacidofile, Alicyclobacillus cycloheptanicus has been developed. This involved regioselective Grignard coupling between cycloheptylmagnesium bromide and methyl 11-bromoundecanoate (2), prepared from 10- undecanoic acid.

Sham A. Hassarajani; Vasant R. Mamdapur

1998-01-01

336

Demonstration of functional coupling between ?-aminobutyric acid (GABA) synthesis and vesicular GABA transport into synaptic vesicles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

l-Glutamic acid decarboxylase (GAD) exists as both membrane-associated and soluble forms in the mammalian brain. Here, we propose that there is a functional and structural coupling between the synthesis of ?-aminobutyric acid (GABA) by membrane-associated GAD and its packaging into synaptic vesicles...

Jin, Hong; Wu, Heng; Osterhaus, Gregory; Wei, Jianning; Davis, Kathleen; Sha, Di; Floor, Eric; Hsu, Che-Chang; Kopke, Richard D.

337

Sulfonic acid functionalised ordered mesoporous materials as catalysts for fine chemical synthesis.  

Science.gov (United States)

The synthesis of highly active acid catalysts supported on ordered mesoporous materials has eluded chemists until 1998, when Wim M. Van Rhijn et al. explored three different routes to tether sulfonic acid on mesoporous silica. This viewpoint sheds light on this landmark and explores its significant impact on material science and green catalysis. PMID:23990025

El Kadib, Abdelkrim; Finiels, Annie; Brunel, Daniel

2013-08-30

338

Sulfonic acid functionalised ordered mesoporous materials as catalysts for fine chemical synthesis.  

UK PubMed Central (United Kingdom)

The synthesis of highly active acid catalysts supported on ordered mesoporous materials has eluded chemists until 1998, when Wim M. Van Rhijn et al. explored three different routes to tether sulfonic acid on mesoporous silica. This viewpoint sheds light on this landmark and explores its significant impact on material science and green catalysis.

El Kadib A; Finiels A; Brunel D

2013-10-01

339

?-Transaminase-catalyzed asymmetric synthesis of unnatural amino acids using isopropylamine as an amino donor.  

UK PubMed Central (United Kingdom)

Isopropylamine is an ideal amino donor for reductive amination of carbonyl compounds by ?-transaminase (?-TA) owing to its cheapness and high volatility of a ketone product. Here we developed asymmetric synthesis of unnatural amino acids via ?-TA-catalyzed amino group transfer between ?-keto acids and isopropylamine.

Park ES; Dong JY; Shin JS

2013-07-01

340

Abolished synthesis of cholic acid reduces atherosclerotic development in apolipoprotein E knockout mice[S  

Digital Repository Infrastructure Vision for European Research (DRIVER)

To investigate the effects of abolished cholic acid (CA) synthesis in the ApoE knockout model [apolipoprotein E (apoE) KO],a double-knockout (DKO) mouse model was created by crossbreeding Cyp8b1 knockout mice (Cyp8b1 KO), unable to synthesize the primary bile acid CA, with apoE KO mice. After 5 mont...

Slätis, Katharina; Gåfvels, Mats; Kannisto, Kristina; Ovchinnikova, Olga; Paulsson-Berne, Gabrielle; Parini, Paolo

 
 
 
 
341

Sulfonic acid functionalised ordered mesoporous materials as catalysts for fine chemical synthesis.  

UK PubMed Central (United Kingdom)

The synthesis of highly active acid catalysts supported on ordered mesoporous materials has eluded chemists until 1998, when Wim M. Van Rhijn et al. explored three different routes to tether sulfonic acid on mesoporous silica. This viewpoint sheds light on this landmark and explores its significant impact on material science and green catalysis.

El Kadib A; Finiels A; Brunel D

2013-08-01

342

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

International Nuclear Information System (INIS)

[en] 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)

1994-01-01

343

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

1986-05-29

344

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

345

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

International Nuclear Information System (INIS)

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

1975-12-18

346

Synthesis of oligomers derived from amide-linked neuraminic acid analogues.  

UK PubMed Central (United Kingdom)

N-Fluoren-9-ylmethoxycarbonyl-protected sugar amino acids derived from alpha-O-methoxy- and 2,3-dehydroneuraminic acids have been prepared. Incorporation of these monomer units into solid-phase synthesis led to the efficient synthesis of two series of oligomers varying from one to eight units in length. The (1-->5)-linked amides of 2,3-dehydroneuraminic acid were further subjected to hydrogenation giving a third series of oligomers with a beta-hydrido substituent at the anomeric carbon.

Gregar TQ; Gervay-Hague J

2004-02-01

347

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).

1982-01-01

348

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

349

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

International Nuclear Information System (INIS)

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

2008-08-01

350

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-08-01

351

Optimization of enzymatic synthesis of palm-based kojic acid ester using response surface methodology.  

Science.gov (United States)

Kojic acid monooleate is a fatty acid derivative of kojic acid which can be widely used as a skin whitening agent in a cosmetic applications. In avoiding any possible harmful effects from chemically synthesized product, the enzymatic synthesis appears to be the best way to satisfy the consumer demand nowadays. The ability of immobilized lipase from Rhizomucor meihei (lipozyme RMIM) to catalyze the direct esterification of kojic acid and oleic acid was investigated. Response Surface Methodology (RSM) and 5-level-4-factor central composite rotatable were employed to evaluate the effects of synthesis parameters such as enzyme amount (0.1-0.4 g), temperature (30-60 degrees C), substrate molar ratio (1-4 mmol, kojic acid:oleic acid) and reaction time (24-48 h) on percentage molar conversion to kojic acid monooleate. Analysis of the product using TLC, GC and FTIR showed the presence of kojic acid monooleate. The optimal conditions for the enzymatic reaction were obtained after analysis with backward elimination using 0.17 g of enzyme and 4 mmol of substrate at 52.50 degrees C for 42 h. Under these conditions the esterification percentage was 37.21%. The results demonstrated that response surface methodology can be applied effectively to optimize the lipase-catalysed synthesis of kojic acid monooleate. The optimum conditions can be used to scale up the process. PMID:19745577

Ashari, Siti Efliza; Mohamad, Rosfarizan; Ariff, Arbakariya; Basri, Mahiran; Salleh, Abu Bakar

2009-01-01

352

Optimization of enzymatic synthesis of palm-based kojic acid ester using response surface methodology.  

UK PubMed Central (United Kingdom)

Kojic acid monooleate is a fatty acid derivative of kojic acid which can be widely used as a skin whitening agent in a cosmetic applications. In avoiding any possible harmful effects from chemically synthesized product, the enzymatic synthesis appears to be the best way to satisfy the consumer demand nowadays. The ability of immobilized lipase from Rhizomucor meihei (lipozyme RMIM) to catalyze the direct esterification of kojic acid and oleic acid was investigated. Response Surface Methodology (RSM) and 5-level-4-factor central composite rotatable were employed to evaluate the effects of synthesis parameters such as enzyme amount (0.1-0.4 g), temperature (30-60 degrees C), substrate molar ratio (1-4 mmol, kojic acid:oleic acid) and reaction time (24-48 h) on percentage molar conversion to kojic acid monooleate. Analysis of the product using TLC, GC and FTIR showed the presence of kojic acid monooleate. The optimal conditions for the enzymatic reaction were obtained after analysis with backward elimination using 0.17 g of enzyme and 4 mmol of substrate at 52.50 degrees C for 42 h. Under these conditions the esterification percentage was 37.21%. The results demonstrated that response surface methodology can be applied effectively to optimize the lipase-catalysed synthesis of kojic acid monooleate. The optimum conditions can be used to scale up the process.

Ashari SE; Mohamad R; Ariff A; Basri M; Salleh AB

2009-01-01

353

Theoretical investigations on the synthesis mechanism of cyanuric acid from NH3 and CO 2.  

UK PubMed Central (United Kingdom)

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.

Cheng X; Zhao Y; Zhu W; Liu Y

2013-09-01

354

Role of Escherichia coli beta-ketoacyl-ACP synthase I in unsaturated fatty acid synthesis.  

UK PubMed Central (United Kingdom)

Two activities were found in E. coli extracts which could complement unsaturated fatty acid synthesis of a cerulenin treated E. coli fatty acid synthetase. One of these is beta-ketoacyl-ACP synthase I, but it is not known whether the other activity represents the previously characterized beta-ketoacyl-ACP synthase II. A mutant strain exhibiting a temperature sensitive unsaturated fatty acid synthetic activity apparently lacked an active beta-ketoacyl-ACP synthase I.

Siggaard-Andersen M

1988-01-01

355

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

UK PubMed Central (United Kingdom)

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.

Chisholm MH; Feil F; Hadad CM; Patmore NJ

2005-12-01

356

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

357

Synthesis and characterization of humic acids with distinct redox capacities  

Energy Technology Data Exchange (ETDEWEB)

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

Sachs, S.; Heise, K.H.; Bernhard, G.

2002-05-01

358

A convenient synthesis of amino acid methyl esters.  

UK PubMed Central (United Kingdom)

A series of amino acid methyl ester hydrochlorides were prepared in good to excellent yields by the room temperature reaction of amino acids with methanol in the presence of trimethylchlorosilane. This method is not only compatible with natural amino acids, but also with other aromatic and aliphatic amino acids.

Li J; Sha Y

2008-01-01

359

A convenient synthesis of amino acid methyl esters.  

Science.gov (United States)

A series of amino acid methyl ester hydrochlorides were prepared in good to excellent yields by the room temperature reaction of amino acids with methanol in the presence of trimethylchlorosilane. This method is not only compatible with natural amino acids, but also with other aromatic and aliphatic amino acids. PMID:18560331

Li, Jiabo; Sha, Yaowu

2008-05-08

360

Synthesis and tissue biodistribution of [?-11C]palmitic acid. A novel PET imagining agent for cardiac fatty acid metabolism  

International Nuclear Information System (INIS)

In order to diagnose patients with medium-chain acyl-CoA dehydrogenase deficiency with a noninvasive diagnostic technique such as positron emission tomography, they have developed a synthesis of [?-11C]palmitic acid. The radiochemical synthesis was achieved by coupling an alkylfuran Grignard reagent (7) with [11C]methyl iodide, followed by rapid oxidative cleavage of the furan ring to the carboxylate using ruthenium tetraoxide. Tissue biodistribution studies in rags comparing [?-11C]palmitic acid and [1-11C]palmitic acid show that the %ID/g and %ID/organ in the heart tissue after administration of [?-11C]palmitic acid is approximately 50% greater than after administration of [1-11C]palmitic acid, due to the diminished metabolism of the [?-11C]palmitic acid. These studies show as well, low uptake in nontarget tissues (blood, lung, kidney, and muscle). PET images of a dog heart obtained after administration of [?-11C]- and [1-11C]palmitic acid show virtually identical uptake and distribution in the myocardium. The differing cardiac washout of labeled palmitates measured by dynamic PET studies may allow diagnosis of disorders in cardiac fatty acid metabolism.

1994-01-01

 
 
 
 
361

An efficient synthesis of quinoxalines catalyzed by monoammonium salt of 12-tungstophosphoric acid  

Directory of Open Access Journals (Sweden)

Full Text Available Monoammonium salt of 12-tungstophosphoric acid [(NH4)H2PW12O40] catalyst was used for the synthesis of biologically important quinoxaline derivatives in excellent yields from various aromatic 1,2-dicarbonyl and 1,2-diamines. The methodology has the advantages of mild reaction conditions with simple workup procedure, even for the synthesis of quinoxaline derivatives from sterically hindered diamine.

Vijayalakshmi Kunkuma; Lakshmi Anu Prabhavathi Devi Bethala; Yadagiri Bhongiri; Badari Narayana Prasad Rachapudi; Seetharamanjaneya Sai Prasad Potharaju

2011-01-01

362

Synthesis of the novel (±)-2-methoxy-6-icosynoic acid--a fatty acid that induces death of neuroblastoma cells.  

UK PubMed Central (United Kingdom)

The first total synthesis for the novel fatty acid (±)-2-methoxy-6-icosynoic acid was accomplished in seven steps and in a 14% overall yield starting from 2-(4-bromobutoxy)-tetrahydro-2H-pyran. The title compound displayed an EC50=23±1 ?M against the human SH-SY5Y neuroblastoma cell line and an EC50=26±1 ?M against the human adenocarcinoma cervix cell line (HeLa) after 48 h of exposure. The corresponding non-methoxylated analog 6-icosynoic acid did not display cytotoxicity (EC50>500 ?M) toward the studied cell lines as well as the 2-methoxyicosanoic acid (EC50>300 ?M). The critical micelle concentration (CMC=20-30 ?M) for the (±)-2-methoxy-6-icosynoic acid was also determined. It was found that ?-methoxylation decreases the CMC of a fatty acid.

Orellano EA; Cartagena MM; Rosado K; Carballeira NM

2013-07-01

363

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

Energy Technology Data Exchange (ETDEWEB)

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.

Antsypovitch, Sergei I [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

2002-01-31

364

Measurement of bile acid synthesis by 14CO2: the metabolism of propionyl CoA.  

Science.gov (United States)

The relationship between 14CO2 evolution from the catabolism of [26 or 2714C] cholesterol to bile acids was studied in rats with biliary fistulae. When equal quantities of [26 or 2714C] cholesterol and [414C] cholesterol were administered, there was a significant linear relationship between 14CO2 expiration in the breath and [414C] bile acid excreted in the bile. Bile acid synthesis calculated as the ratio of 14CO2: molar specific activity of biliary cholesterol correlated highly with biliary bile acid excretion in the bile acid depleted rat. Phenobarbital, a known inducer of gamma-amino levulenic acid formation from succinyl CoA did not alter the relationship between the 14CO2 estimation of bile acid synthesis and biliary bile acid excretion, indicating that the relationship between [26 or 2714C] cholesterol side chain cleavage and 14CO2 formation was not altered. Phenobarbital, however, did cause a reduction in bile acid synthesis measured by 14CO2 evolution and by biliary bile acid excretion. The 14CO2 method underestimated bile acid excretion. 8.7% in untreated and phenobarbital treated rats respectively. Since 11% of the radioactivity which was expired as 14CO2 was isolated as bile acids, radioactivity cleaved as [1 or 314C] propionyl CoA may enter cholesterol-bile acid biosynthesis resulting in the underestimation of bile acid synthesis. To test whether radioactivity from propionyl CoA enters steroid biosynthesis [114C] propionate and [214C] propionate were given to untreated biliary fistula rats and the biliary lipids excreted in 60 hours were analyzed. Incorporation of radioactivity into cholesterol and bile acids was greater after the administration of [214C] propionate than after [114C] propionate than after [114C] propionate, suggesting that radioactivity from propionyl CoA may enter steroid biosynthesis by metabolic events in which the methylene and carboxyl carbon atoms are differentiated. Although the use of 14CO2 expiration from [26 or 2714C] cholesterol catabolism underestimates the rate of bile acid synthesis, it should have many applications because of the constant relationship between 14CO2 formation and cholesterol side chain cleavage. PMID:1202660

Davis, R A; Showalter, P; Kern, F

1975-10-01

365

Measurement of bile acid synthesis by 14CO2: the metabolism of propionyl CoA.  

UK PubMed Central (United Kingdom)

The relationship between 14CO2 evolution from the catabolism of [26 or 2714C] cholesterol to bile acids was studied in rats with biliary fistulae. When equal quantities of [26 or 2714C] cholesterol and [414C] cholesterol were administered, there was a significant linear relationship between 14CO2 expiration in the breath and [414C] bile acid excreted in the bile. Bile acid synthesis calculated as the ratio of 14CO2: molar specific activity of biliary cholesterol correlated highly with biliary bile acid excretion in the bile acid depleted rat. Phenobarbital, a known inducer of gamma-amino levulenic acid formation from succinyl CoA did not alter the relationship between the 14CO2 estimation of bile acid synthesis and biliary bile acid excretion, indicating that the relationship between [26 or 2714C] cholesterol side chain cleavage and 14CO2 formation was not altered. Phenobarbital, however, did cause a reduction in bile acid synthesis measured by 14CO2 evolution and by biliary bile acid excretion. The 14CO2 method underestimated bile acid excretion. 8.7% in untreated and phenobarbital treated rats respectively. Since 11% of the radioactivity which was expired as 14CO2 was isolated as bile acids, radioactivity cleaved as [1 or 314C] propionyl CoA may enter cholesterol-bile acid biosynthesis resulting in the underestimation of bile acid synthesis. To test whether radioactivity from propionyl CoA enters steroid biosynthesis [114C] propionate and [214C] propionate were given to untreated biliary fistula rats and the biliary lipids excreted in 60 hours were analyzed. Incorporation of radioactivity into cholesterol and bile acids was greater after the administration of [214C] propionate than after [114C] propionate than after [114C] propionate, suggesting that radioactivity from propionyl CoA may enter steroid biosynthesis by metabolic events in which the methylene and carboxyl carbon atoms are differentiated. Although the use of 14CO2 expiration from [26 or 2714C] cholesterol catabolism underestimates the rate of bile acid synthesis, it should have many applications because of the constant relationship between 14CO2 formation and cholesterol side chain cleavage.

Davis RA; Showalter P; Kern F Jr

1975-10-01

366

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

Energy Technology Data Exchange (ETDEWEB)

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.

Junker, L.H.; Davis, R.A. (Univ. of Colorado Health Sciences Center, Denver (USA))

1989-12-01

367

Diastereoselective hydrophosphonylation of imines using (R,R)-TADDOL phosphite. Asymmetric synthesis of alpha-aminophosphonic acid derivatives.  

UK PubMed Central (United Kingdom)

Efficient synthesis of alpha-aminophosphonic acid derivatives is achieved, the key step being a diastereoselective hydrophosphonylation of N-diphenylphosphinyl imines using a readily available chiral cyclic (R,R)-TADDOL-phosphite derived from inexpensive natural tartaric acid.

Palacios F; Olszewski TK; Vicario J

2010-10-01

368

Importance of glutamine for gamma-aminobutyric acid synthesis in rat neostriatum in vivo.  

UK PubMed Central (United Kingdom)

This work was carried out to evaluate the importance of glial cells in providing precursors for the in vivo synthesis of gamma-aminobutyric acid (GABA). Fluorocitrate, which selectively inhibits the tricarboxylic acid cycle in glial cells, was administered locally in rat neostriatum. Inhibition of the glial cell tricarboxylic acid cycle led to a decrease both in glutamine level and in gamma-vinyl GABA (GVG)-induced GABA accumulation, an observation indicating reduced GABA synthesis. The role of glutamine, which is synthesized in glial cells as a precursor for GABA, was further investigated by inhibition of glutamine synthetase with intrastriatally administered methionine sulfoximine. In this case, the glutamine level was reduced to near zero values, and the GVG-induced GABA accumulation was only half that of normal. The results show that glutamine is an important precursor for GABA synthesis, but it cannot be the sole precursor because it was not possible to depress the GVG-induced GABA accumulation completely.

Paulsen RE; Odden E; Fonnum F

1988-10-01

369

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.

Keiko Hojo; Natsuki Shinozaki; Yoshimi Nozawa; Yoshinobu Fukumori; Hideki Ichikawa

2013-01-01

370

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

UK PubMed Central (United Kingdom)

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.

Huang H; McIntosh AL; Martin GG; Petrescu AD; Landrock KK; Landrock D; Kier AB; Schroeder F

2013-01-01

371

Early effects of dietary orotic acid upon liver lipid synthesis and bile cholesterol secretion in rats  

Energy Technology Data Exchange (ETDEWEB)

Dietary orotic acid is known to cause impaired fatty acid synthesis and increased cholesterol synthesis in rats. The authors found that the impaired fatty acid synthesis occurs during the first day of orotic acid feeding and, in studies with albumin-bound (1-/sup 14/C)palmitic acid, an associated decrease in the rate of esterification of this fatty acid into triacylglycerol, phospholipid, and cholesteryl ester was observed. These changes may result from the known decreases in liver levels of adenine nucleotides or, as reported here, from decreased liver CoASH levels in orotic acid-fed rats. The increase in hepatic cholesterol synthesis occurred during the second day of orotic acid feeding. It was detected by increased incorporation of (1,2-/sup 14/C)acetate into cholesterol by liver slices and by a 7-fold increase in HMG-CoA reductase activity. At the same time the biliary output of cholesterol was increased 2-fold and studies using /sup 3/H/sub 2/O revealed that the output of newly synthesized cholesterol in bile was increased 5-fold. The content of cholesteryl ester in hepatic microsomes decreased during orotic acid feeding but free cholesterol was unchanged. The findings are interpreted to suggest that the increased bile cholesterol secretion caused by orotic acid is a result of impaired hepatic cholesterol esterification and that the increase in HMG-CoA reductase activity is a result of diminished negative feedback due to the depleted content of cholesteryl ester in the hepatic microsomes.

Tokmakjian, S.D.; Haines, D.S.

1985-04-01

372

Enzymatic surface hydrolysis of poly(ethylene terephthalate) and bis(benzoyloxyethyl) terephthalate by lipase and cutinase in the presence of surface active molecules  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A lipase from Thermomyces lanuginosus and cutinases from Thermobifida fusca and Fusarium solani hydrolysed poly(ethylene terephthalate) (PET) fabrics and films and bis(benzoyloxyethyl) terephthalate (3PET) endo-wise as shown by MALDI-Tof-MS, LC–UVD/MS, cationic dyeing and XPS analysis. Due to interf...

Eberl, A.; Heumann, Sonja; Brückner, T.; Araújo, Rita; Paulo, Artur Cavaco; Kaufmann, F.; Kroutil, W.; Gübitz, Georg M.

373

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

374

Palladium-catalyzed multicomponent synthesis of 2-imidazolines from imines and acid chlorides.  

Science.gov (United States)

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 CHCl(3) 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. PMID:23174894

Xu, Boran; Worrall, Kraig; Arndtsen, Bruce A

2012-11-22

375

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; Kraig Worrall; Bruce A. Arndtsen

2012-01-01

376

Communic Acids: Occurrence, Properties and Use as Chirons for the Synthesis of Bioactive Compounds  

Directory of Open Access Journals (Sweden)

Full Text Available Communic acids are diterpenes with labdane skeletons found in many plant species, mainly conifers, predominating in the genus Juniperus (fam. Cupresaceae). In this review we briefly describe their distribution and different biological activities (anti- bacterial, antitumoral, hypolipidemic, relaxing smooth muscle, etc.). This paper also includes a detailed explanation of their use as chiral building blocks for the synthesis of bioactive natural products. Among other uses, communic acids have proven useful as chirons for the synthesis of quassinoids (formal), abietane antioxidants, ambrox and other perfume fixatives, podolactone herbicides, etc., featuring shorter and more efficient processes.

Alejandro F. Barrero; M. Mar Herrador; Pilar Arteaga; Jesús F. Arteaga; Alejandro F. Arteaga

2012-01-01

377

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

378

Synthesis and properties of peptide dendrimers containing fluorescent and branched amino acids.  

UK PubMed Central (United Kingdom)

In this report, we describe dendritic peptides possessing central fluorescent amino acids with adjacent branched amino acids. These fluorescent-peptide dendrimers were prepared using (9-fluorenyl)methoxycarbonyl (Fmoc)-based solid-phase peptide synthesis and Fmoc-derivative fluorescent and branched amino acids. The branched amino acids featured multiple carboxylic acids in their side chains, making the fluorescent-peptide dendrimers highly water-soluble compared with the analogous peptides containing the fluorescent amino acids only. The branched amino acid units also improved the fluorescence intensity of the dendrimers. Based on high-pressure liquid chromatography and fluorescence spectroscopy results, we determined that the fluorescent groups were located in the core and that the carboxylic acids were located on the surface of the dendrimers. Fluorescence resonance energy transfer was achieved among the three proximal fluorescent groups in one of the fabricated fluorescent-peptide dendrimers. © 2012 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 100: 64-70, 2013.

Kitamatsu M; Kitabatake M; Noutoshi Y; Ohtsuki T

2013-04-01

379

A Convenient Synthesis of Amino Acid Methyl Esters  

Directory of Open Access Journals (Sweden)

Full Text Available A series of amino acid methyl ester hydrochlorides were prepared in good toexcellent yields by the room temperature reaction of amino acids with methanol in thepresence of trimethylchlorosilane. This method is not only compatible with natural aminoacids, but also with other aromatic and aliphatic amino acids.

Jiabo Li; Yaowu Sha

2008-01-01

380

Synthesis of alpha-hydroxyphosphonic acids from Lesquerella oil  

Science.gov (United States)

Lesquerella oil has been a substance of growing chemical interest, due to the ease with which it is produced and its similarity in structure to castor oil. The primary fatty acid in Lesquerella oil, lesquerolic acid, is very similar to the principal component of castor oil, ricinoleic acid, and may ...

 
 
 
 
381

Amino acids augment muscle protein synthesis in neonatal pigs during acute endotoxemia by stimulating mTOR-dependent translation initiation  

Science.gov (United States)

In skeletal muscle of adults, sepsis reduces protein synthesis by depressing translation initiation and induces resistance to branched-chain amino acid stimulation. Normal neonates maintain a high basal muscle protein synthesis rate that is sensitive to amino acid stimulation. In the present study...

382

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).

1985-01-01

383

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

384

Synthesis and radioprotective activity of cinnamic acid thioester derivative  

International Nuclear Information System (INIS)

In order to find more effective radioprotective agents from cinnamic acid thioester derivatives, the structure of P - hydroxy-cinnamic acid and sinapic acid into 4'-O-carbethoxy-2-chloro-cinnamic acid diethylaminoethylthiol esterhydrochloride and 3, 4, 5,-trimethoxyphenylpropenolic acid diethylamino ethylthiol ester hydrochloride has been changed. The main step of synthesize of these agents involved the condensation of 4'-O-carbethoxy-phenylpropenoic acid chloride with diethylaminoethylthiol under base catalyst. The protective test on mice irradiated with 60Co ?-rays of 7.5?8.0 Gy was shown that the animal survival rate was enhanced by 30% within 30 days after irradiation in comparison with the control group. The MS, IR and NMR spectra data of cinnamic acid thioester derivative have also been reported. The ESR spectra of the compound was discussed.

1997-01-01

385

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.

HU Shen-rong; CHEN Xi

2009-01-01

386

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

Directory of Open Access Journals (Sweden)

Full Text Available 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

2008-01-01

387

Synthesis of L-glutamic acid stereospecifically labeled at C-4 with deuterium  

Energy Technology Data Exchange (ETDEWEB)

4-(/sup 2/H/sub 2/)-L-glutamic acid was prepared in excellent yield by enzymatic reductive amination of 4-(/sup 2/H/sub 2/)-2-ketoglutaric acid. The synthesis of stereospecifically deuterated (4 R) and (4 S)-(4-/sup 2/H/sub 2/)-L-glutamic acids from (2 RS, 4 S) and (2 RS, 4 R)-4-hydroxyglutamic acids, involving a reduction step by sodium cyanoboro-deuteride, was shown to proceed with 75% inversion of configuration.

Ducrocq, C.; Decottignies Le-Marechal, P.; Azerad, R. (Paris-11 Univ., 91 - Orsay (France). Inst. of Biochemistry)

1985-01-01

388

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

Scientific Electronic Library Online (English)

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

Campo, Vanessa Leiria; Carvalho, Ivone

2008-01-01

389

Asymmetric Synthesis Using Novel Cationic Diether-Coordinated Lewis Acid and Stereoselective Synthesis of Piperidones and 1,2-Amino Alcohols ???????????????????????????????????????????1,2-????????????????  

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CONTENTS , Chapter 1.Asymmetric Synthesis Using Novel Cationic Diether-Coordinated Lewis Acids ,   1-1.Introduction / p1 ,   1-2.Cationic Lewis Acids for [4+2]Type Cycloaddition of ?-Chiral Aldimines / p12 ,   1-3.Development of Novel Cationic Lewis Acids Coordinated by a Chiral Diether Ligand / p18 ,   1-4.Attemp...

??, ???; ????, ???; Ishimaru, Kaori

390

Synthesis of racemic, R- and S-(1- sup 11 C)-. beta. -hydroxybutyric acid  

Energy Technology Data Exchange (ETDEWEB)

Racemic, R- and S-{beta}-hydroxybutyric acid were labelled with {sup 11}C in the carboxylic position by a two-step stereospecific synthesis starting with carrier-added ({sup 11}C)cyanide and R/S, R- or S-propylene oxide. Hydrolysis of the intermediate nitrile with hydrochloric acid gave racemic (1-{sup 11}C)-{beta}-hydroxybutyric acid and R- or S-(1-{sup 11}C)-{beta}-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 ({sup 11}C)cyanide. The radiochemical purity of the products was > 99%. (author).

Thorell, J.-O.; Stone-Elander, S. (Karolinska Pharmacy, Stockholm (Sweden) Karolinska Hospital and Inst., Stockholm (Sweden). Dept. of Clinical Neurophysiology); Koenig, W.A. (Hamburg Univ. (Germany). Organic Chemistry Inst.); Halldin, C. (Karolinska Hospital and Inst., Stockholm (Sweden). Dept. of Psychiatry and Psychology); Widen, L. (Karolinska Hospital and Inst., Stockholm (Sweden). Dept. of Clinical Neurophysiology)

1991-06-01

391

[Enzyme activity of citrate, glyoxylate and pentosephosphate cycles during synthesis of citric acids by Candida lipolytica  

UK PubMed Central (United Kingdom)

The activity of key enzymes of the citrate and glyoxylate cycles was compared in yeast cells during intensive synthesis of citric acids and in its absence in the course of growth of Candida lipolytica on glucose ("glucose" yeast cells) and on hexadecane ("hexadecane" yeast cells). Citrate and isocitrate were found to be formed by the yeast in the tricarboxylic acid cycle. The ability of the yeast for "overproduction" of citrate and isocitrate during its growth on glucose and hexadecane depends on the high activity of the key enzyme of cycle, citrate synthase, as compared with the activity of other enzymes of the tricarboxylic acid cycle. Citrate predominated among excreted acids during growth on glucose in conditions of nitrogen deficiency while isocitrate prevailed during growth on hexadecane. The predominating synthesis of citrate in the first case seems to be related to a lower activity of aconitase in the "glucose" cells as compared with the "hexadecane" cells.

Glazunova LM; Finogenova TV

1976-05-01

392

Solid-phase synthesis of europium and terbium complexes of quinolinic acid  

International Nuclear Information System (INIS)

The regularities of mechanochemical synthesis and spectral-luminescent properties of europium and terbium compounds with dicarboxylic quinoline acid were studied. The compounds Ln2(XH)3D ? 2H2O, Ln = Eu3+, Tb3+, XH - quinoline acid anion, D - 1,10-phenanthroline, 2,2'-dipyridyl, diphenyl guanidine, benzotriazole were prepared. The synthesis of the europium and terbium complexes aqueous solutions was also conducted for comparison by the reaction of the rare earth chlorides(nitrates) with alcohol solution of the acid and neutral ligand. The data of element analysis and X-ray diffraction are given. IR-spectra and luminescence spectra of europium and quinoline acid synthesized as mechanochemically, so traditional method, are identical to each other

2002-01-01

393

The solubilities of benzene polycarboxylic acids in water  

International Nuclear Information System (INIS)

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

2006-01-01

394

The solubilities of benzene polycarboxylic acids in water  

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-05-15

395

Synthesis of ( sup 14 CO)ellagic acid  

Energy Technology Data Exchange (ETDEWEB)

({sup 14}CO)Ellagic acid with a chemical purity of 98.9% and radiochemical purity of 99.9% was synthesized with an overall yield of 16% (both chemically and radiochemically). Reaction of {sup 14}CO{sub 2} with lithiated 3,4,5-trimethoxybenzene and demethylation of the resulting 3,4,5-trimethoxybenzoic acid was followed by esterification and coupling of methyl gallate into ellagic acid. Two efficient coupling methods were employed: direct aeration and aeration of methyl gallate in the presence of the phenolic oxidase, tyrosinase. The latter method produced the highest yield and purity. This preparation produced ({sup 14}CO)ellagic acid with a specific activity of 20 mCi/mmol. The yields of labeled 3,4,5-trimethoxybenzoic acid and ellagic acid based on Ba{sup 14}CO{sub 3} were 65% and 16%, respectively. (author).

Wenguang Zeng; Heur, Y.-H.; Stoner, G.D. (Medical Coll. of Ohio, Toledo, OH (United States)); Kinstle, T.H. (Bowling Green State Univ., OH (United States))

1991-06-01

396

THE SYNTHESIS OF SALICYLATE PROMPTED BY BR0NSTED ACIDIC IONIC LIQUIDS  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english Brønsted acidic ionic liquids based on imidazolium cation were employed as a series of efficient and environmentally benign catalysts and solvents for the synthesis of salicylate, the yields could reach 76%-96%. The optimal reaction conditions were determined. The results showed that Brønsted acidic ionic liquids were efficient catalysts and solvents which could be recycled easily without obvious decline in catalytic activities.

JIANG, DONG; LIU, JIE; YUAN WANG, YUAN; DAI, LI YI

2009-01-01

397

Acid-mediated prevention of aspartimide formation in solid phase peptide synthesis.  

UK PubMed Central (United Kingdom)

Aspartimide formation is one of the major obstacles that impedes the solid phase synthesis of large peptides and proteins. Until now, no cost-effective strategy to suppress this side reaction has been developed. Here it is demonstrated that addition of small amounts of organic acids to the standard Fmoc cleavage agent piperidine efficiently prevents formation of aspartimide side products. This effect is shown to be virtually independent of the acid strength.

Michels T; Dölling R; Haberkorn U; Mier W

2012-10-01

398

THE SYNTHESIS OF SALICYLATE PROMPTED BY BR0NSTED ACIDIC IONIC LIQUIDS  

Directory of Open Access Journals (Sweden)

Full Text Available Brønsted acidic ionic liquids based on imidazolium cation were employed as a series of efficient and environmentally benign catalysts and solvents for the synthesis of salicylate, the yields could reach 76%-96%. The optimal reaction conditions were determined. The results showed that Brønsted acidic ionic liquids were efficient catalysts and solvents which could be recycled easily without obvious decline in catalytic activities.

DONG JIANG; JIE LIU; YUAN YUAN WANG; LI YI DAI

2009-01-01

399

Bifunctional Role of Thiosalicylic Acid in the Synthesis of Silver Nanoparticles  

Directory of Open Access Journals (Sweden)

Full Text Available Conventional synthesis of silver nanoparticles employs a reducing agent and a capping agent. Surfactants are effec-tive capping agents as they prevent the aggregation of nanoparticles during storage and use. However, the biocompatibility of several of the surfactants is questionable. In this report, the use of thiosalicylic acid as both reducing and capping agent is reported. Compared to conventional synthesis, this methodology requires higher temperature for synthesis, which then is expected to result in aggregates of larger size. The ability of three different synthesis methodologies – direct heating, photochemical and microwave dielectric treatment were evaluated and assessed on the basis of the size, size distribution and stability of the particles. Microwave irradiation was found to be most suitable for achieving particles with a hydrodynamic diameter of 10 nm. Our studies indicate that -COO- group is involved in the reduction of Ag+ and –SH group of TSA is involved in the capping of the nanoparticles.

Ramasamy Indumathy; Kalarical Janardhanan Sreeram; Muralidharan Sriranjani; Cheravathoor Poulose Aby; Balachandran Unni Nair

2010-01-01

400

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)

2010-01-01

 
 
 
 
401

Efficient Microwave-Assisted Synthesis of Ionic Esterified Amino Acids  

Directory of Open Access Journals (Sweden)

Full Text Available In this work, an efficient microwave-assisted methodology for the esterification of unprotected ?-amino acids is described. Ionic esterified amino acids were synthesized in satisfactory yields in a facile one-pot solventless protocol from unprotected amino acids and alcohols under acid catalysis (MsOH or p-TsOH) to afford the pure products after a simple work-up procedure. This procedure can also be extended to the preparation of long and short chain alkyl and benzyl esters.

Ricardo Cerón-Camacho; Jorge Aburto; Luisa E. Montiel; Eugenio A. Flores; Frisia Cuellar; Rafael Martínez-Palou

2011-01-01

402

Research on polyantimonic acid synthesis and adsorption for strontium  

International Nuclear Information System (INIS)

[en] The paper describes a new method for Polyantimonic Acid (PAA) synthesized and absorb capacity of Sr2+ and UO22+ on PAA. PAA synthesized by oxidation process with SbCl3 is with good mechanical strength and suitable for column operation. PAA has high affinity for Strontium in acid solution, and the adsorption capacity for Sr2+ is 42 mg/g in 0.1 mol/L nitrate acid solution. But the adsorption capacity of UO22+ on PAA is 27.7 mg/g. The results show that PAA can be used for 90Sr removal from acid solution without UO22+. (authors)

2008-01-01

403

Decarbonylative approach to the synthesis of enamides from amino acids: stereoselective synthesis of the (Z)-aminovinyl-D-cysteine unit of mersacidin.  

UK PubMed Central (United Kingdom)

The Pd- and Ni-promoted decarbonylation of amino acid thioesters proceeds smoothly to yield enamides. The synthesis of the (S)-(Z)-AviMeCys subunit of mersacidin, an MRSA-active lantibiotic, via this approach, is described.

García-Reynaga P; Carrillo AK; VanNieuwenhze MS

2012-02-01

404

PROCESSES FOR THE PURIFICATION OF BIS(2-HYDROXYETHYL) TEREPHTHALATE  

UK PubMed Central (United Kingdom)

The invention aims at providing a process for recovering high-purity bis(2-hydroxylethyl) terephthalate (BHET) efficiently from an ethylene glycol (EG) solution containing crude BHET, particularly a depolymerization solution obtained by depolymerizing a polyester comprising polyethylene terephthalate (PET) as the main component with EG, while suppressing the formation of impurities such as diethylene glycol (DEG), DEG esters and oligomers.; The invention relates to a process for the purification of BHET which comprises crystallizing the depolymerization solution under specified temperature conditions and subjecting the obtained mixture to solid-liquid separation, and to a process for the purification of BHET which comprises the evaporation step of evaporating low-boiling components from the depolymerization solution under specified conditions to thereby obtain a melt and the molecular distillation step of distilling the obtained melt under specified conditions and recovering a specific fraction.

INADA SHUJI; SATO KIKUCHI

405

PROCESSES FOR THE PURIFICATION OF BIS(2-HYDROXYETHYL) TEREPHTHALATE  

UK PubMed Central (United Kingdom)

An object of the present invention is to provide a method of obtaining BHET of high purity efficiently from an EG (ethylene glycol) solution containing crude BHET (bis(2-hydroxyethyl)terephthalate), especially a decomposition product solution obtained by decomposing a polyester containing PET (polyethylene terephthalate) as a main component, by use of EG, while minimizing by-production of impurity components such as DEG (diethylene glycol), DEG ester and oligomers. The present invention is a method of purifying BHET by subjecting the decomposition product solution to crystallization and solid-liquid separation under specific temperature conditions.; Further, the present invention is a method of purifying BHET which comprises evaporation steps of evaporating low-boiling-point components from the decomposition product solution under specific conditions so as to obtain a melt solution and a molecular distillation step of distilling the obtained melt solution under specific conditions so as to obtain a specific fraction.

INADA SHUJI; SATO KIKUCHI

406

One-pot synthesis of ?-amino phosphonates from ?-amino acids and ?-amino alcohols  

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5 pages, 1 figure, 1 table, 4 schemes.-- Printed version published Nov 7, 2005. , The one-pot radical fragmentation–phosphorylation reaction of ?-amino acids and ?-amino alcohols affords ?-amino phosphonates in good yields. The reaction was applied to the synthesis of potentially bioactive phosphonates...

Boto, Alicia; Gallardo, Juan Antonio; Hernández, Rosendo; Saavedra, Carlos J.

407

The Solid-Phase Synthesis of PolyglutamateSS OF Folic Acid.  

Science.gov (United States)

Details of an unambiguous chemical synthesis by which pteroyl-(gamma-L-glutamyl)n-L-glutamic acid of any desired chain length (up to n = 6) may be prepared are reported. The procedures employed are modifications of the Merrifield solid-phase peptide synth...

C. L. Krumdieck C. M. Baugh

1968-01-01

408

Total synthesis of (-)-dihydroprotolichesterenic acid via diastereoselective conjugate addition to chiral fumarates.  

Science.gov (United States)

A diastereoselective conjugate addition of a variety of monoorganocuprates, Li[RCuI], to chiral fumarates to provide funtionalized succinates has been developed. The utility of this reaction is demonstrated in a concise total synthesis of (-)-dihydroprotolichesterenic acid that required only four steps and proceeded in an overall 31% yield. PMID:23539490

Hethcox, J Caleb; Shanahan, Charles S; Martin, Stephen F

2013-02-11

409

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

International Nuclear Information System (INIS)

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

1993-01-01

410

o-Iodoxybenzoic acid mediated oxidative desulfurization initiated domino reactions for synthesis of azoles.  

UK PubMed Central (United Kingdom)

A systematic exploration of thiophilic ability of o-iodoxybenzoic acid (IBX) for oxidative desulfurization to trigger domino reactions leading to new methodologies for synthesis of different azoles is described. A variety of highly substituted oxadiazoles, thiadiazoles, triazoles, and tetrazoles have been successfully synthesized in good to excellent yields, starting from readily accessible thiosemicarbazides, bis-diarylthiourea, 1,3-disubtituted thiourea, and thioamides.

Chaudhari PS; Pathare SP; Akamanchi KG

2012-04-01

411

2-(hydroxymethyl)aspartic acid: synthesis, crystal structure, and reaction with a transaminase  

Energy Technology Data Exchange (ETDEWEB)

The synthesis and x-ray crystal structure of 2-(hydroxymethyl) aspartic acid and the preliminary evaluation of its interaction with cytosolic aspartate aminotransferase of pig heart are described. A dissociation constant 1.4 mM for the L-2-(hydroxymethyl) aspartate complex with the enzyme was obtained. 2 figures. (DP)

Walsh, J.J.; Metzler, D.E.; Powell, D.; Jacobson, R.A.

1980-11-05

412

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

Directory of Open Access Journals (Sweden)

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

Minoo Dabiri; Sahareh Bashiribod

2009-01-01

413

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.

Juha Koivukorpi; Elina Sievänen; Erkki Kolehmainen; Vladimír Král

2007-01-01

414

Synthesis and biological activity of some novel fluorenone-, 2- or 7-nitrofluorenone-1-carbonylamino acid derivatives  

Directory of Open Access Journals (Sweden)

Full Text Available The synthesis of fluorenone-, 2- or 7-nitrofluorenone-1-carbonylamino acid methyl ester and hydrazide derivatives IV-XXX is described. Many of the products were found to be active against a number of microorganisms. The spectral data of the synthesized compounds IV-XXX and the results of biological screening are briefly discussed.

S. A. M. SHEDID; H. M. HASSAN

1999-01-01

415

Dialdehyde-containing nucleic acids and their components: synthesis, properties and affinity modification of proteins  

International Nuclear Information System (INIS)

Synthesis, structure and chemical properties of nucleoside dialdehyde derivatives are described. The introduction of aldehyde groups into oligonucleotides is discussed. The methods of affinity modification of proteins with periodate-oxidised nucleic acid derivatives are considered. The bibliography includes 48 references.

1999-03-31

416

The Bile Acid Synthesis Pathway Is Present and Functional in the Human Ovary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background: Bile acids, end products of the pathway for cholesterol elimination, are required for dietary lipid and fat-soluble vitamin absorption and maintain the balance between cholesterol synthesis in the liver and cholesterol excretion. They are composed of a steroid structure and are primarily...

Nierstenhoefer, Maik; Tobiasch, Edda; Usheva, Anny; Smith, Laura; Yoo, Sang Wook; Penzias, Alan Stewart

417

The potential of ¹¹C-acetate PET for monitoring the Fatty acid synthesis pathway in Tumors.  

UK PubMed Central (United Kingdom)

Positron emission tomography (PET) is a molecular imaging modality that provides the opportunity to rapidly and non-invasively visualize tumors derived from multiple organs. In order to do so, PET utilizes radiotracers, such as ¹?F-FDG and ¹¹C-acetate, whose uptake coincides with altered metabolic pathways within tumors. Increased expression and activity of enzymes in the fatty acid synthesis pathway is a frequent hallmark of cancer cells. As a result, this pathway has become a prime target for therapeutic intervention. Although multiple drugs have been developed that both directly and indirectly interfere with fatty acid synthesis, an optimal means to assess their efficacy is lacking. Given that ¹¹Cacetate is directly linked to the fatty acid synthesis pathway, this probe provides a unique opportunity to monitor lipogenic tumors by PET. Herein, we review the relevance of the fatty acid synthesis pathway in cancer. Furthermore, we address the potential utility of ¹¹C-acetate PET in imaging tumors, especially those that are not FDG-avid. Last, we discuss several therapeutic interventions that could benefit from ¹¹C-acetate PET to monitor therapeutic response in patients with certain types of cancers.

Deford-Watts LM; Mintz A; Kridel SJ

2013-03-01

418

Total synthesis of (-)-dihydroprotolichesterenic acid via diastereoselective conjugate addition to chiral fumarates.  

UK PubMed Central (United Kingdom)

A diastereoselective conjugate addition of a variety of monoorganocuprates, Li[RCuI], to chiral fumarates to provide funtionalized succinates has been developed. The utility of this reaction is demonstrated in a concise total synthesis of (-)-dihydroprotolichesterenic acid that required only four steps and proceeded in an overall 31% yield.

Hethcox JC; Shanahan CS; Martin SF

2013-04-01

419

Improved synthesis of 3-(dialkylaminomethyl)-indole in acetic acid aqueous solution under ultrasound irradiation.  

UK PubMed Central (United Kingdom)

Synthesis of Mannich bases related to gramine via Mannich reaction of secondary amine, formaldehyde and indole or N-methylindole can be carried out in 69-98% yields in acetic acid aqueous solution at 35°C under ultrasound irradiation. Compared with the method using stirring, the present procedure provided several advantages such as milder conditions, shorter reaction time and higher yield.

Li JT; Sun SF; Sun MX

2011-01-01

420

Improved synthesis of 3-(dialkylaminomethyl)-indole in acetic acid aqueous solution under ultrasound irradiation.  

Science.gov (United States)

Synthesis of Mannich bases related to gramine via Mannich reaction of secondary amine, formaldehyde and indole or N-methylindole can be carried out in 69-98% yields in acetic acid aqueous solution at 35°C under ultrasound irradiation. Compared with the method using stirring, the present procedure provided several advantages such as milder conditions, shorter reaction time and higher yield. PMID:20646952

Li, Ji-Tai; Sun, Shao-Feng; Sun, Ming-Xuan

2010-06-02

 
 
 
 
421

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

UK PubMed Central (United Kingdom)

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

Muraviev D

2003-01-01

422

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

Science.gov (United States)

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

Muraviev, D

2003-01-01

423

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...

424

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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, suggest...

Juha Koivukorpi; Elina Sievänen; Erkki Kolehmainen; Vladimír Král

425

Polyphosphoric acid promoted synthesis of 10,11-dihydrobenzo[j]fluoranthen-12-one.  

UK PubMed Central (United Kingdom)

A straightforward synthesis of 3,8-dimethoxy-10,11-dihydrobenzo[j]fluoranthen-12-ones 1 is reported in a seven-step route from biphenyl-4,4'-diol 2 via the transformation of a double Claisen rearrangement, cross metathesis with ethyl acrylate, and polyphosphoric acid (PPA)-promoted Friedel-Crafts electrophilic benzannulation in good yields.

Chang MY; Lee TW; Wu MH

2012-05-01

426

Polyphosphoric acid promoted synthesis of 10,11-dihydrobenzo[j]fluoranthen-12-one.  

Science.gov (United States)

A straightforward synthesis of 3,8-dimethoxy-10,11-dihydrobenzo[j]fluoranthen-12-ones 1 is reported in a seven-step route from biphenyl-4,4'-diol 2 via the transformation of a double Claisen rearrangement, cross metathesis with ethyl acrylate, and polyphosphoric acid (PPA)-promoted Friedel-Crafts electrophilic benzannulation in good yields. PMID:22515182

Chang, Meng-Yang; Lee, Tein-Wei; Wu, Ming-Hao

2012-04-19

427

Synthesis of 2-(alkylamino)-1-phenylethane-1-thiosulfuric acids, potential schistosomicides  

Directory of Open Access Journals (Sweden)

Full Text Available The total synthesis of seven here-to-fore unreported aromatic aminoalkanethiosulfuric acids, their physical properties and those of the aminoalcohol and bromoalkanamine intermediates are reported. All structures were established by including ¹H and 13C NMR, IR and MS spectroscopy and elemental analysis.

Moreira Liliani Salum Alves; Piló-Veloso Dorila; Nelson David Lee

2000-01-01

428

Synthesis of alkaloid analogues from ?-amino acids by one-pot radical decarboxylation/alkylation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

8 pages, 1 figure, 7 schemes.-- Printed version published Aug 2005. , A mild, one-pot methodology to obtain ?-substituted nitrogen heterocycles from commercial amino acids is reported. This versatile procedure has been applied to the synthesis of different alkaloid analogues in good to excellent yields...

Boto, Alicia; León, Yolanda de; Gallardo, Juan Antonio; Hernández, Rosendo

429

Synthesis of functionalized nitrogen heterocycles by radical decarboxylation of ?- and ?-amino acids  

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10 pages, 1 figure, 2 tables, 9 schemes.-- Supporting information available: Synthesis and spectroscopic data of compounds 18–22 and 25 and the synthetic intermediates 44 and 45. , Iodinated or oxygenated nitrogen heterocycles are obtained by radical decarboxylation of ?- and ?-amino acids. This mild, ...

Boto, Alicia; Hernández, Rosendo; León, Yolanda de; Murguía, José R.; Rodríguez-Afonso, Abigail

430

Synthesis of Glycosides of Glucuronic, Galacturonic and Mannuronic Acids: An Overview  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Uronic acids are carbohydrates present in relevant biologically active compounds. Most of the latter are glycosides or oligosaccharides linked by their anomeric carbon, so their synthesis requires glycoside-bond formation. The activation of this anomeric center remains difficult due to the presence ...

Anne Wadouachi; José Kovensky

431

FATTY EPOXIDE SYNTHESIS WITH PEROXYGENASE AND HYDROLYSIS WITH ALUMINA AND PERCHLORIC ACID  

Science.gov (United States)

Polyhydroxy fatty acids and esters are known to be natural metabolites in both plants and animals and their chemical derivatives may have commercial uses as natural emulsifiers and surfactants in a variety of functional areas. A main route for the chemical synthesis and biosynthesis of these polyh...

432

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.

1980-01-01

433

Effect of pressure on the crystallization behaviour of polyethylene terephthalate  

CERN Multimedia

Crystallized polyethylene terephthalate (PET) samples were obtained at high pressures of 200-400 MPa at a temperature of 603 K, and another group of the samples were made at pressures of 250-350 MPa and different temperatures with a fixed supercooling. The samples were investigated by means of differential scanning calorimetry and scanning electron microscopy. Characterization results suggested that high pressure could increase the crystallization rate and promote the thickening process of PET lamellar crystals.

Li Li; Huang Rui

2002-01-01

434

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

Science.gov (United States)

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

435

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...

436

Synthesis of highly lipophilic crown ether carboxylic acids  

Energy Technology Data Exchange (ETDEWEB)

Synthetic routes to eight highly lipophilic crown ether carboxylic acids are described. Structural variations within this series of crown ether carboxylic acids include changes in the crown ether cavity size, the lipophilic group attachment site, and the basicity of the crown ether oxygens.

Bartsch, R.A.; Liu, Y.; Kang, S.I.; Son, B.; Heo, G.S.; Hipes, P.G.; Bills, L.J.

1983-01-01

437

Synthesis of 2-naphtalene-d/sub 7/-sulfonic acid  

Energy Technology Data Exchange (ETDEWEB)

2-Naphthalene-d/sub 7/-sulfonic acid, required as an internal standard for the analysis of organic compounds in water by gas chromatography/mass spectrometry, was synthesized in one step from commercially available naphthalene-d/sub 8/ and sulfuric acid-d/sub 2/.

Sniegoski, L.T.; White, E.V.; Konarsh, P.L. (National Bureau of Standards, Washington, DC (USA))

1982-09-01

438

[Asymmetric synthesis of aromatic L-amino acids catalyzed by transaminase].  

UK PubMed Central (United Kingdom)

Aromatic L-Amino acids are important chiral building blocks for the synthesis of many drugs, pesticides, fine chemicals and food additives. Due to the high activity and steroselectivity, enzymatic synthesis of chiral building blocks has become the main research direction in asymmetric synthesis field. Guided by the phylogenetic analysis of transaminases from different sources, two representative aromatic transaminases TyrB and Aro8 in type I subfamily, from the prokaryote Escherichia coli and eukaryote Saccharomyces cerevisia, respectively, were applied for the comparative study of asymmetric transamination reaction process and catalytic efficiency of reversely converting keto acids to the corresponding aromatic L-amino acid. Both TyrB and Aro8 could efficiently synthesize the natural aromatic amino acids phenylalanine and tyrosine as well as non-natural amino acid phenylglycine. The chiral HPLC analysis showed the produced amino acids were L-configuration and the e.e value was 100%. L-alanine was the optimal amino donor, and the transaminase TyrB and Aro8 could not use D-amino acids as amino donor. The optimal molar ratio of amino donor (L-alanine) and amino acceptor (aromatic alpha-keto acids) was 4:1. Both of the substituted group on the aromatic ring and the length of fatty acid carbon chain part in the molecular structure of aromatic substrate alpha-keto acid have the significant impact on the enzyme-catalyzed transamination efficiency. In the experiments of preparative-scale transamination synthesis of L-phenylglycine, L-phenylalanine and L-tyrosine, the specific production rate catalyzed by TryB were 0.28 g/(g x h), 0.31 g/(g x h) and 0.60 g/(g x h) and the specific production rate catalyzed by Aro8 were 0.61 g/(g x h), 0.48 g/(g x h) and 0.59 g/(g x h). The results obtained here were useful for applying the transaminases to asymmetric synthesis of L-amino acids by reversing the reaction balance in industry.

Xia W; Sun Y; Min C; Han W; Wu S

2012-11-01

439

[Effect of cultivation conditions on the synthesis of citric and isocitric acids in Candida lipolytica on hexadecane medium  

UK PubMed Central (United Kingdom)

The influence of aeration, pH and iron concentration on the growth of yeast C. lipolytica 704 on the hexadecane medium and on the synthesis of citric and isocitric acids was investigated. The yeast synthesized citric acids actively during intensive aeration. The acid formation was strongly dependent on the medium acidity: pH 6.0 was most favourable for the synthesis of citric acids. The Fe concentration influenced significantly the ratio of the acids synthesized. At a low concentration of iron (0.005 mg Fe/l) equal amounts of citrate and isocitrate were formed; at an increased concentration isocitrate was in predominant formation.

Illarionova VI; Finogenova TV; Glazunova LM

1975-03-01

440

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

UK PubMed Central (United Kingdom)

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

Jeon E; Lee S; Won JI; Han SO; Kim J; Lee J

2011-06-01

 
 
 
 
441

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

Science.gov (United States)

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

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

2011-04-08

442

Dyeing properties of poly(methyl vinyl pyridine)-poly(ethylene terephthalate) graft copolymers  

International Nuclear Information System (INIS)

[en] Grafting of poly(ethylene terephthalate) fibers (PET) with 2-methyl-5-vinylpyridine (MVP) was carried out using ? rays and benzoyl peroxide independently for the initiation of grafting. The poly(MVP)-PET graft copolymers we