- Biosynthesis of isocitric acid in repeated-batch culture and testing of its stress-protective activity
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Biosynthesis of Ds(+)-threo-isocitric acid from ethanol in the Yarrowia lipolytica batch and repeated-batch cultures was studied. Repeated-batch cultivation was found to provide for a good biosynthetic efficiency of the producer for as long as 748?h, probably due to maintenance of high activities of enzymes involved in the biosynthesis of isocitric acid. Under optimal repeated-batch cultivation conditions, the producer accumulated 109.6?g/L Ds(+)-threo-isocitric acid with a production rate of 1.346?g/L?h. The monopotassium salt of isocitric acid isolated from the culture liquid and purified to 99.9% was found to remove neurointoxication, to restore memory, and to improve the learning of laboratory rats intoxicated with lead and molybdenum salts. Taking into account the fact that the neurotoxic effect of heavy metals is mainly determined by oxidative stress, the aforementioned favorable action of isocitric acid on the intoxicated rats can be explained by its antioxidant activity among other pharmacological effects.
- Morgunov, Igor G.,Kamzolova, Svetlana V.,Karpukhina, Olga V.,Bokieva, Svetlana B.,Inozemtsev, Anatoly N.
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- Discovery and Biosynthesis of Bolagladins: Unusual Lipodepsipeptides from Burkholderia gladioli Clinical Isolates**
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Two Burkholderia gladioli strains isolated from the lungs of cystic fibrosis patients were found to produce unusual lipodepsipeptides containing a unique citrate-derived fatty acid and a rare dehydro-β-alanine residue. The gene cluster responsible for the
- Challis, Gregory L.,Dashti, Yousef,Jian, Xinyun,Mahenthiralingam, Eshwar,Mullins, Alex J.,Nakou, Ioanna T.,Webster, Gordon
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- SYNTHESIS OF 4-(HYDROXYMETHYL)TETRAHYDRO-4-PYRANOL - A NEW INTERMEDIATE FOR THE PREPARATION OF SYNTHETIC CITRIC ACID
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The hydroxylation of 4-methylenetetrahydropyran with hydrogen peroxide in the presence of various acidic catalysts was investigated.The oxidation of 4-(hydroxymethyl)tetrahydro-4-pyranol with concentrated nitric acid leads to citric acid in 50percent yield.
- Gevorkyan, A. A.,Kazaryan, P. I.,Sargysyan, M. S.,Petrosyan, K. A.,Mkrtumyan, S. A.
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- Citric acid production from xylan and xylan hydrolysate by semi-solid culture of Aspergillus niger
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Citric acid production from xylan and xylan hydrolysate was done by Aspergillus niger Yang no. 2 cultivated in a semi-solid culture using bagasse as a carrier. Yang no. 2 produced 72.4 g/l and 52.6 g/l of citric acid in 5 d from 140 g/l of xylose and arabinose, respectively. Yang no. 2 produced 51.6 g/l of citric acid in 3 d from a concentrated xylan hydrolysate prepared by cellulase treatment, containing 100 g/l of reducing sugars. Moreover, Yang no. 2 directly produced 39.6 g/l of citric acid maximally in 3 d from 140 g/l of xylan.
- Kirimura, Kohtaro,Watanabe, Taisei,Sunagawa, Tadahiro,Usami, Shoji
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- Absolute stereochemical course of the 3-carboxymuconate cycloisomerases from Pseudomonas putida and Acinetobacter colcoaceticus: Analysis and implications
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The absolute stereochemical course of the 3-carboxymuconate cycloisomerases [EC 5.5.1.2; 2-carboxy-5-oxo-2,5-dihydrofuran-2-acetate lyase (decyclizing)] from Pseudomonas putida and Acinetobacter calcoaceticus has been determined by chemical and 1H NMR methods. The product of the enzyme-catalyzed reaction in 2H2O was detected by NMR and trapped by catalytic hydrogenation to afford 5-[2H]homocitrate lactone. Subsequent chemical degradation of the monodeuteriated homocitrate lactone gave (2r,3S)-2-[2H]citrate as determined by 1H NMR analysis. The product of the cycloisomerase reaction was established as (4R,5R)-5-[2H]-4-carboxymuconate, indicating that the lactonization proceeded by an anti addition - the mechanistic and stereochemical antipode of the previously studied muconate cycloisomerase from P. putida and 3-carboxymuconate cycloisomerase from Neurospora crassa. The anti addition probably represents the lower energy pathway for the reaction and suggests that the evolutionary relationship between the two classes of cycloisomerases is more remote than previously believed.
- Chari,Whitman,Kozarich,et al.
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- ACIDIC Nα-ACYLARGININE DERIVATIVES IN ARGININE-ACCUMUTATING PLANT TISSUES
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Two new acidic Nα-acylarginine derivatives were isolated from arginin-accumulating plant tissues.The first, Nα-(2-hydroxy-2-carboxymethylsuccinyl)-L-arginine, was isolated from bulbs of Lilium maximowiczii, whilst the second, Nα-(2-hydroxysuccinyl)arginine, was obtained from tubers of Smilax china and seeds of Vicia faba.No acidic Nα-acylarginine derivatives was detected, however, in roots of Rumex obtusifolius which contained fairly large amounts of arginine and malonic acid.Key Wors Index: Lilium maximowiczii; Smilax china; Vicia faba; Rumex obtusifolius;Liliaceae; Leguminosae; Polygonacea; acylarginine derivatives; Nα-(2-hydroxy-2-carboxymethylsuccinyl)-L-arginine; Nα-(2-hydroxysuccinyl)arginine
- Kasai, Takanori,Shiroshita, Yoshinari,Uomoto, Katsuhito,Sakamura, Sadao
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- Citrate inhibition of cisplatin reaction with DNA studied using fluorescently labeled oligonucleotides: Implication for selectivity towards guanine
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The reaction between cisplatin and DNA is conveniently studied using fluorescently labeled oligonucleotides and gel electrophoresis; as an example of application, the inhibition of this reaction by citrate is demonstrated, which might increase selectivity
- Wang, Feng,Huang, Po-Jung Jimmy,Liu, Juewen
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- Cyanide as a primordial reductant enables a protometabolic reductive glyoxylate pathway
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Investigation of prebiotic metabolic pathways is predominantly based on abiotically replicating the reductive citric acid cycle. While attractive from a parsimony point of view, attempts using metal/mineral-mediated reductions have produced complex mixtures with inefficient and uncontrolled reactions. Here we show that cyanide acts as a mild and efficient reducing agent mediating abiotic transformations of tricarboxylic acid intermediates and derivatives. The hydrolysis of the cyanide adducts followed by their decarboxylation enables the reduction of oxaloacetate to malate and of fumarate to succinate, whereas pyruvate and α-ketoglutarate themselves are not reduced. In the presence of glyoxylate, malonate and malononitrile, alternative pathways emerge that bypass the challenging reductive carboxylation steps to produce metabolic intermediates and compounds found in meteorites. These results suggest a simpler prebiotic forerunner of today’s metabolism, involving a reductive glyoxylate pathway without oxaloacetate and α-ketoglutarate—implying that the extant metabolic reductive carboxylation chemistries are an evolutionary invention mediated by complex metalloproteins. [Figure not available: see fulltext.].
- Krishnamurthy, Ramanarayanan,Pulletikurti, Sunil,Yadav, Mahipal,Yerabolu, Jayasudhan R.
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p. 170 - 178
(2022/02/11)
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- Bacterial flavoprotein monooxygenase YxeK salvages toxic S-(2-succino)-adducts via oxygenolytic C–S bond cleavage
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Thiol-containing nucleophiles such as cysteine react spontaneously with the citric acid cycle intermediate fumarate to form S-(2-succino)-adducts. In Bacillus subtilis, a salvaging pathway encoded by the yxe operon has recently been identified for the detoxification and exploitation of these compounds as sulfur sources. This route involves acetylation of S-(2-succino)cysteine to N-acetyl-2-succinocysteine, which is presumably converted to oxaloacetate and N-acetylcysteine, before a final deacetylation step affords cysteine. The critical oxidative cleavage of the C–S bond of N-acetyl-S-(2-succino)cysteine was proposed to depend on the predicted flavoprotein monooxygenase YxeK. Here, we characterize YxeK and verify its role in S-(2-succino)-adduct detoxification and sulfur metabolism. Detailed biochemical and mechanistic investigation of YxeK including 18O-isotope-labeling experiments, homology modeling, substrate specificity tests, site-directed mutagenesis, and (pre-)steady-state kinetics provides insight into the enzyme’s mechanism of action, which may involve a noncanonical flavin-N5-peroxide species for C–S bond oxygenolysis.
- Ellis, Holly R.,Kammerer, Bernd,Lagies, Simon,Matthews, Arne,Sch?nfelder, Julia,Schleicher, Erik,Stull, Frederick,Teufel, Robin
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- Catalytic Oxidation of VOCs over SmMnO3 Perovskites: Catalyst Synthesis, Change Mechanism of Active Species, and Degradation Path of Toluene
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Highly active samarium manganese perovskite oxides were successfully prepared by employing self-molten-polymerization, coprecipitation, sol-gel, and impregnation methods. The physicochemical properties of perovskite oxides were investigated by XRD, N2 adsorption-desorption, XPS, and H2-TPR. Their catalytic performances were compared via the catalytic oxidation of toluene. The perovskite prepared by self-molten-polymerization possessed the highest catalytic capacity, which can be ascribed to its higher oxygen adspecies concentration (Olatt/Oads = 0.53), higher surface Mn4+/Mn3+ ratio (Mn4+/Mn3+ = 0.95), and best low-temperature reducibility (H2 consumption = 0.27; below 350 °C). The most active catalyst also exhibited good cycling and long-term stability for toluene oxidation. After a multistep cycle reaction and a long-term reaction of 42 h, the toluene conversion maintained above 99.9% at 270 °C. Mechanistic study hinted that lattice oxygen was involved in toluene oxidation. The oxidation reaction was dependent on the synergism of lattice oxygen, adsorbed oxygen, and oxygen vacancies. The degradation pathway of toluene, researched by diffuse reflectance infrared Fourier transform spectroscopy and online mass spectrometry technologies, demonstrated that a series of organic byproducts existed at a relatively low temperature. This work provides an efficient and practical method for selecting highly active catalysts and for exploring the catalytic mechanism for the removal of atmospheric environmental pollution.
- Liu, Lizhong,Sun, Jiangtian,Ding, Jiandong,Zhang, Yan,Jia, Jinping,Sun, Tonghua
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p. 14275 - 14283
(2019/10/17)
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- Highly Active Mn3-xFexO4 Spinel with Defects for Toluene Mineralization: Insights into Regulation of the Oxygen Vacancy and Active Metals
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A series of highly defected Mn3-xFexO4 spinels with different amounts of oxygen vacancies and active metals were successfully synthesized by regulating the insertion of Fe ions into the crystal structure of Mn3O4 via self-polymerizable monomer adjustment of the molten Mn-Fe salt dispersion. The characterization of X-ray diffraction, Raman, scanning electron microscopy, X-ray photoelectron spectroscopy, and N2 adsorption-desorption showed that the doping of Fe increased the lattice defects, oxygen vacancy concentration, specific surface area, mesoporosity, and catalytic properties compared to Cu ions doping. Temperature-programmed reduction with hydrogen and oxygen pulse chemisorption tests determined that the doping level of Fe ions had an important influence on the oxygen vacancy content and the dispersion of active metals on the catalysts' surfaces. For the best Mn-dispersed and most active Mn2.4Fe0.6O4 catalyst, a long-term toluene oxidation measurement running for 120 h of uninterrupted reaction, at the low temperature of 240 °C, high humidity (relative humidity = 100%), and high weight hourly space velocity of 60000 mL·g-1·h-1, was also carried out, which indicated that the catalyst possessed high stability and endurability. Moreover, the continuous oxidation route and internal principle for toluene oxidation were also revealed by the in situ diffuse-reflectance infrared Fourier transform spectroscopy and gas chromatography-mass spectrometry techniques and deep dynamics study.
- Liu, Lizhong,Sun, Jiangtian,Ding, Jiandong,Zhang, Yan,Sun, Tonghua,Jia, Jinping
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supporting information
p. 13241 - 13249
(2019/10/21)
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- Nanopore enriched hollow carbon nitride nanospheres with extremely high visible-light photocatalytic activity in the degradation of aqueous contaminants of emerging concern
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Construction of highly efficient hollow nanosphere photocatalytic systems has been strongly attracting the attention of researchers. In the present work, nanopore enriched hollow carbon nitride nanospheres (HCNNSs) with a smaller particle size (200 nm) and a thinner shell thickness (40 nm) are successfully fabricated by a silica-nanocasting strategy. Such unique structures possess many advantages such as large BET surface area (122 m2 g-1), high light-harvesting ability, fast charge separation and transfer efficiency, plentiful exposed active sites and enhanced oxidation ability of photogenerated holes (h+VB). Therefore, HCNNSs in smaller sizes (HCNNS-200) exhibit extremely excellent visible-light photocatalytic efficiency towards the degradation of contaminants of emerging concern, e.g. levofloxacin (LEVO), in comparison with bulk g-C3N4 and HCNNSs in larger sizes (HCNNS-500). And it takes less than 10 min to finish the degradation of LEVO. The experimental results including those from indirect chemical probing, electron spin resonance, ion chromatography and high performance liquid chromatography-mass spectrometry confirm that h+VB and O2- are the active species that are responsible for the mineralization of LEVO to NO3-, F-, H2O and CO2 under visible-light irradiation. Additionally, the degradation pathway of LEVO in the HCNNS-200 photocatalytic system is also proposed. It is expected that HCNNS-200 can be used as a promising photocatalyst for environmental remediation.
- Yang, Yuxin,Hu, An,Wang, Xinyue,Meng, Jiaqi,Guo, Yihang,Huo, Mingxin,Zhu, Suiyi
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p. 355 - 365
(2019/01/28)
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- Two new phenolic glycosides from the rhizome of Gastrodia elata
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Two new phenolic glycosides, named parishins F-G (1-2), together with known parishin E, were isolated from the rhizome of Gastrodia elata. The new structures were established as 1,3-di-[4-O-(β-d-glucopyranosyl) benzyl]-2-{4-O-[β-d-glucopyranosyl-(1→6)-β-d
- Wang, Li,Xiao, Hong-Bin,Yang, Li,Wang, Zheng-Tao
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experimental part
p. 457 - 462
(2012/07/17)
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- HETEROCYCLIC COMPOUNDS
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Provided is a compound having a monoamine reuptake inhibitory activity, which is represented by the formula (I) wherein ring A is an optionally substituted 6-membered aromatic ring, ring B is the substituents on ring A are optionally bonded to form, together with ring A, an optionally substituted 9- or 10-membered aromatic fused ring, and other symbols are as defined in the specification, or a salt thereof.
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(2012/04/18)
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- Kinetics of Ga(NOTA) formation from weak Ga-citrate complexes
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Gallium complexes are gaining increasing importance in biomedical imaging thanks to the practical advantages of the 68Ga isotope in Positron Emission Tomography (PET) applications. 68Ga has a short half-time (t1/2 = 68 min); thus the 68Ga complexes have to be prepared in a limited time frame. The acceleration of the formation reaction of gallium complexes with macrocyclic ligands for application in PET imaging represents a significant coordination chemistry challenge. Here we report a detailed kinetic study of the formation reaction of the highly stable Ga(NOTA) from the weak citrate complex (H3NOTA = 1,4,7-triazacyclononane-1,4, 7- triacetic acid). The transmetalation has been studied using 71Ga NMR over a large pH range (pH = 2.01-6.00). The formation of Ga(NOTA) is a two-step process. First, a monoprotonated intermediate containing coordinated citrate, GaHNOTA(citrate), forms in a rapid equilibrium step. The rate-determining step of the reaction is the deprotonation and slow rearrangement of the intermediate accompanied by the citrate release. The observed reaction rate shows an unusual pH dependency with a minimum at pH 5.17. In contrast to the typical formation reactions of poly(amino carboxylate) complexes, the Ga(NOTA) formation from the weak citrate complex becomes considerably faster with increasing proton concentration below pH 5.17. We explain this unexpected tendency by the role of protons in the decomposition of the GaHNOTA(citrate)* intermediate which proceeds via the protonation of the coordinated citrate ion and its subsequent decoordination to yield the final product Ga(NOTA). The stability constant of this intermediate, log K GaHNOTA(citrate) = 15.6, is remarkably high compared to the corresponding values reported for the formation of macrocyclic lanthanide(III)-poly(amino carboxylates). These kinetic data do not only give mechanistic insight into the formation reaction of Ga(NOTA), but might also contribute to establish optimal experimental conditions for the rapid preparation of Ga(NOTA)-based radiopharmaceuticals for PET applications.
- Morfin, Jean-Francois,Toth, Eva
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experimental part
p. 10371 - 10378
(2011/12/03)
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- METHOD FOR PREPARING CITRIC ACID
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Provided is a method for preparing citric acid comprising the following steps: (1) contacting and reacting the fermentation liquid of citric acid with calcium carbonate and/or calcium hydroxide under the condition that the citric acid in the fermentation liquid can be converted into calcium hydrogen citrate, and subjecting the obtained slurry to a solid-liquid separation to obtain solid calcium hydrogen citrate and a first liquid phase; (2) subjecting the solid calcium hydrogen citrate obtained in step (1) to acidolysis to obtain citric acid; (3) contacting and reacting the first liquid phase obtained in step (1) with calcium carbonate and/or calcium hydroxide under the condition that the calcium hydrogen citrate dissolved in the first liquid phase can be converted into calcium citrate, subjecting the obtained slurry to a solid-liquid separation to obtain solid calcium citrate, and recycling the solid calcium citrate to step (1).
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(2011/05/06)
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- PROCESS FOR THE PREPARATION OF SUBSTITUTED BENZILIC ACID FROM SUBSTITUTED BENZILS
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The classical process for the rearrangement of substituted benzil to benzilic acid is performed in the presence of sodium or potassium hydroxide as a base using ethanol-ether as a medium. The reaction requires reflux temperature for complete conversion. However, these bases containing metallic ions and generate metallic containing effluent waste which may require additional expenditure for treatment. Moreover, because of corrosive nature of base, and use of flammable solvent, the safety measures are needed during large scale production. Another method also reported for benzilic acid rearrangement at 380° C. which is practically not feasible. The present invention describes the use of quaternary ammonium hydroxides as a base for the rearrangement of the substituted benzils to benzilc acids. It also avoids the use of solvent and reaction can be carried out at relatively lower temperatures. Because of the solvent free reaction condition it reduces the mass/volume of reaction mixture.
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(2010/10/19)
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- Separation of citric acid from gluconic acid in fermentation broth using a weakly or strongly basic anionic exchange resin adsorbent
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Citric acid is separated from a fermentation broth containing gluconic acid by using an adsorbent comprising a water-insoluble, macroreticular or gel, strongly or weakly basic anionic exchange resin possessing quaternary or tertiary amine functional groups, said a anionic exchange resin having a cross-linked acrylic or styrene resin matrix and a desorbent comprising water or dilute sulfuric acid. The pH of the feed is maintained below the first ionization constant (pKa1) of citric acid to maintain selectivity.
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(2008/06/13)
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- PROCESS FOR RECOVERING ORGANIC COMPOUNDS FROM AQUEOUS STREAMS CONTAINING SAME
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A method for a liquid-liquid extraction of hydrophilic organic compounds from aqueous solutions thereof is described. The method generally includes intermixing a sufficient quantity of a specified glycol ether with the aqueous liquor at a first temperature to form a suspension comprising an aqueous raffinate phase and a glycol ether extract phase; separating the glycol ether extract phase from the aqueous raffinate phase; heating the glycol ether extract phase to a second, higher temperature to form a suspension comprising an aqueous extract phase containing a portion of the hydrophilic organic compound and a glycol ether raffinate phase; and separating this glycol ether raffinate phase from the aqueous extract phase. The selected glycol ether has an inverse solubility in water and the partition ratio, value K, for the hydrophilic organic compound is greater than 0.1. This method is useful for recovering valuable hydrophilic organic acids produced via fermentation or produced or used in various manufacturing processes.
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Page/Page column 20
(2008/06/13)
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- The importance of the amide bond nearest the thiol group in enzymatic reactions of coenzyme A
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Analogues of coenzyme A (CoA) and of CoA thioesters have been prepared in which the amide bond nearest the thiol group has been modified. An analogue of acetyl-CoA in which this amide bond is replaced with an ester linkage was a good substrate for the enzymes carnitine acetyltransferase, chloramphenicol acetyltransferase, and citrate synthase, with Km values 2- to 8-fold higher than those of acetyl-CoA and Vmax values from 14 to >80% those of the natural substrate. An analogue in which an extra methylene group was inserted between the amide bond and the thiol group showed less than 4-fold diminished binding to the three enzymes but exhibited less than 1% activity relative to acetyl-CoA with carnitine acetyltransferase and no measurable activity with the other two enzymes. Analogues of several CoA thioesters in which the amide bond was replaced with a hemithioacetal linkage exhibited no measurable activity with the appropriate enzymes. The results indicate that some aspects of the amide bond and proper distance between this amide and the thiol/thioester moiety are critical for activity of CoA ester-utilizing enzymes.
- Xun, Jin,Huang, Haidong,Vogel, Kurt W.,Drueckhammer, Dale G.
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- A PROCESS FOR THE RECOVERY OF CITRIC ACID
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The invention provides a process for the recovery of citric acid from an aqueous solution feed stream originating in fermentation of carbohydrates and utilizing an amine solvent extraction step for separation of impurities comprising: subjecting said aqueous solution feed stream A to a treatment for partial recovery of citric acid, wherein said treatment is other than amine solvent extraction, to form a first portion of purified citric acid B and a secondary feed stream F; subjecting at least a portion G of said secondary feed stream F to a treatment consisting of amine solvent extraction to form a second portion of purified citric acid solution and to reject substantial of impurities initially present in said portion of said secondary feed stream; subjecting said second portion of purified citric acid solution to crystallization; and recycling mother liquor from said crystallization.
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- The use of salts of undecylenoil glutamate and/or undecylenoil hydrolyzate of wheat and/or rice proteins in the formulation of detergent or cosmetic compositions, and compositions containing such salts
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The invention describes detergent or cosmetic compositions having hydrating and preservative properties and simultaneously anti-dandruff and/or anti-odor properties. These compositions comprise a salt of undecylenoil glutamate and/or undecylenoil hydrolyzate of wheat and/or rice proteins. Since such salts are able to perform also a preservative and hydrating effect the compositions of the invention do no need the addition of further preservative or hydrating agents or, at most, contain concentrations thereof which are not efficacious per se.
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- Salts of undecylenoyl glutamate or of undecylenoyl hydrolyzate of wheat or rice proteins in detergent or cosmetic compositions
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The invention describes detergent or cosmetic compositions having hydrating and preservative properties and simultaneously anti-dandruff and/or anti-odour properties. These compositions comprise a salt of undecylenoil glutamate and/or undecylenoil hydrolyzate of wheat and/or rice proteins. Since such salts are able to perform also a preservative and hydrating effect the compositions of the invention do no need the addition of further preservative or hydrating agents or, at most, contain concentrations thereof which are not efficacious per se.
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- 1,4-dihydropyridine compounds as bradykinin antagonists
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PCT No. PCT/IB97/00058 Sec. 371 Date Feb. 1, 1999 Sec. 102(e) Date Feb. 1, 1999 PCT Filed Jan. 27, 1997 PCT Pub. No. WO97/30048 PCT Pub. Date Aug. 21, 1997A compound of formula (I) and its pharmaceutically acceptable salts, wherein A1 and A2 are each halo; X is direct bond, CH2, CO, O, S, S(O) or S(O)2; R1 is selected from a variety of groups such as hydrogen; substituted or unsubstituted C1-4 alkyl; substituted or unsubstituted piperidinyl; substituted or unsubstituted C5-14 cycloalkyl, bicycloalkyl or tricycloalkyl; substituted or unsubstituted C7-14 azacyclo-, azabicyclo- or azatricyclo-alkyl; bicyclo C7-10 alkenyl; benzocyclo C5-7 alkyl; and heterocyclic; R2 is hydrogen, C1-4 alkyl, substituted or unsubstituted phenyl or heterocyclic; and R3 and R4 are each C1-5 alkyl. The novel dihydropyridine compounds of this invention have excellent bradykinin antagonistic activity and are thus useful for the treatment of inflammation, cardiovascular disease, pain, common cold, allergies, asthma, pancreatitis, burns, virus infection, head injury, multiple trauma or the like in mammalian, especially humans.
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- Ion-exchange equilibrium in synthesis of acids on KU-2(H) cation exchanger and of salts on KB-4P-2 cation exchanger
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Advisability of ion-exchange synthesis of acids on strongly acidic KU-2 cation exchanger and of salts on weakly acidic KB-4P-2 cation exchanger is studied.
- Saidakhmedov,Arslanov,Vulikh
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p. 211 - 215
(2007/10/03)
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- Synthesis and spectroscopic study of 13C-labelled citric acids
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The synthesis of (1'-13C)-, (3-13C)- and (2,4-13C2)citric acid from simple starting compounds is described.Using the same procedure, any mono- or multiply-labelled citric acid can be prepared.The 13C-labelled citric acids have been characterized by 1H NMR, 13C NMR and mass spectroscopy.
- Winkel, C.,Buitenhuis, E. G.,Lugtenburg, J.
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- Role of Methylcitric Acid Cycle in Catabolism of Amino Acids by Saccharomycopsis lipolitica
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We examined the production of 2-methylisocitric acid, an intermediate of the constitutive methylcitric acid cycle involved in propionyl-CoA oxidation during the catabolism of different amino acids by a mutant lacking 2-methylisocitrate lyase, a key enzyme of the cycle.The acid was produced equmolarly from isoleucine within a range of amounts of the amino acid added.The amount of the acid produced also increased depending upon the amounts of valine, threonine, methionine, homoserine, and α-aminobutyric acid.However, only a little acid was produced from the 13 other amino acids tested.These results indicated that propionyl-CoA was involved in the catabolism of the first six amino acids named, but not in the other 13.Intramolecular amino acids were therefore part of metabolic turnover and the constitutive cycle functioned in the catabolism of propionyl-CoA derived from the turnover.
- Miyakoshi, Shunichi,Enami, Kengo,Uchiyama, Hiroo,Tabuchi, Takeshi
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p. 1017 - 1022
(2007/10/02)
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- OXIDATION OF 4-METHYLENETETRAHYDROPYRAN AND 4-METHYL-5,6-DIHYDRO-2H-PYRAN WITH NITRIC ACID. SYNTHESIS OF CITRIC AND OXALIC ACIDS
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The oxidation of 4-methylenetetrahydropyran and 4-methyl-5,6-dihydro-2H-pyran with nitric acid was studied.In the presence of an equimolar amount of nitrogen oxide (N2O3 or N2O4) the products from the oxidation of 4-methylenetetrahydropyran are citric and oxalic acids.Under analogous conditions 4-methyl-5,6-dihydro-2H-pyran is oxidized to oxalic acid.During the oxidation of 4-methylenetetrahydropyran and 4-methyl-5,6-dihydro-2H-pyran without the previous addition of nitrogen oxides 3-hydroxy-3-methylglutaric acid is also obtained.
- Sargsyan, M. S.,Mkrtumyan, S. A.,Gevorkyan, A. A.
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p. 1963 - 1967
(2007/10/02)
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- Cosmetic compositions which contain bis-(quaternary ammonium) derivatives with two lipophilic chains and certain said derivatives
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The invention relates to cosmetic compositions which are intended to be used for the treatment of keratin substances. These compositions contain at least one bis(quaternary ammonium) derivative with two lipophilic chains, corresponding to the formula STR1 in which R denotes a saturated or unsaturated, linear or branched aliphatic group having from 8 to 22 carbon atoms, or a mixture of such groups, or mixtures of lipophilic chains derived from natural products having from 8 to 30 carbon atoms, A denotes a group --(CH2)n --, in which n denotes and integer from 1 to 18, R' denotes hydrogen and m=1, it also being possible for A to form a heterocyclic group together with the nitrogen atoms to which it is bonded, in which case m=O, and X- denotes and anion derived from a mineral or organic acid.
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- Production of Isocitric Acid from Glucose by Candida ravautii
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A strain of yeast, No. 325, having been isolated as a threo-Ds-isocitric acid producer and identified as Candida brumptii, was reidentified as Candida ravautii after taxonomical reexamination.All the tested strains of C. ravautii produced mainly isocitric acid.The tested strains were found to be unable to assimilate isocitric acid, although the assimilability of citric acid is one of the taxonomical characteristics of C. ravautii.A mutant was selected as the best producer of isocitric acid in media supplemented with yeast extract: the yield of isocitric acid amounted to about 50percent on the basis of glucose supplied under suitable conditions in shaken culture.
- Oogaki, Masako,Inoue, Madoka,Kaimaktchiev, Atanas C.,Nakahara, Tadaatsu,Tabuchi, Takeshi
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p. 789 - 796
(2007/10/02)
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- Mode of Metabolism of 1-Tetradecene by Candida Yeasts and Citrates Production
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Metabolic pathways for the oxidation of 1-tetradecene by Candida lipolytica were investigated and compared with those for Candida tropicalis in oder to elucidate the difference in the productivity of citrates reported in the previous paper.No difference was found in the pathways for the initial stage of oxidation of 1-tetradecene between the two strains, indicating that the difference in the productivity of citrates is not attributable to the metabolic pathways.The metabolic rate of 1-tetradecene with C. lipolytica was found to be much lower than that with C. tropicalis.The production of citrates was much enhanced in the presence of surfactants which were known to be stimulative for microbial metabolism of hydrocarbons and 11-15 g/liters was attained on the 6th day of cultivation.
- Terasawa, Masato,Takahashi, Joji
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p. 2433 - 2442
(2007/10/02)
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- Facile electroreduction of perrhenate in weakly acidic citrate and oxalate media
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In weakly acidic solution, oxalate and citrate markedly increase the ease of reduction of ReO4- through reversible formation of 1:1 complexes. The citrate complex (ReO4·H2Cit)2- is sufficiently stable that it yields a diffusion limited current, whereas the oxalate complex (ReO4·H2Ox)- is formed only as a transient intermediate and it yields a kinetic limited current. Below pH 3 the mechanism of formation of the citrate complex corresponds to ReO4- + H3Cit ? (ReO4·H2Cit)2- + H+ while above pH 3 it corresponds to ReO4- + H2Cit- ? (ReO4·H2Cit)2-. The enhanced ease of reduction of the citrate and oxalate complexes is ascribed to expansion of the Re coordination sphere from 4 to, e.g., 6 through formation of chelated structures by a concerted process in which the incoming ligand transfers protons to coordinated oxo groups. The hydroxyl group of citric acid is necessary for formation of an easily reduced Re(VII) complex, and Dreiding models indicate that citrate is bidentate and occupies one face of the coordination octahedron, with the hydroxyl group H bonded to a coordinated oxo group.
- Vajo,Aikens,Ashley,Poeltl,Bailey,Clark,Bunce
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p. 3328 - 3333
(2008/10/08)
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- Reaction of Dinitrogen Tetraoxide with Hydrophilic Olefins: Synthesis of Citric and 2-Hydroxy-2-methylbutanedioic Acids
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Liquid olefins typically react with N2O4 by free-radical reactions to form dinitro and nitronitrite derivatives.Introduction of hydrophilic substituents into 1-olefins altered the course of the reaction of the olefins with N2O4 in aqueous HNO3.Citric acid was formed in 64 mol percent yield by the reaction of 3-methylene-1,5-pentanediol with N2O4 in aqueous HNO3.Similarly, 2-hydroxy-2-methylbutanedioic acid was made from 3-methyl-3-buten-1-ol in 88percent yield.These results are explained by solution of the hydrophilic olefins in aqueous HNO3-N2O4 and addition of N2O4 to the double bond as NO+ and NO3- ions to yield nitrosonitrates, which react further to give the final products.
- Wilkes, John B.,Wall, Robert G.
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p. 247 - 250
(2007/10/02)
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- 3,5-Bisoxygenated 2-(ω-halo-3-oxo-1-alkenyl)-cyclopentane-1-heptanoic acids and derivatives thereof
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The compounds of the present invention are useful intermediates for the manufacture of 3,5-dihydroxy-2-(ω-halo-3-hydroxy-1-alkenyl)cyclopentane-1-heptanoic acids and derivatives thereof. The latter compounds display valuable pharmacological properties, e.g. anti-fertility, bronchodilating, anti-secretory, smooth muscle stimulator and blood platelet aggregation-inhibiting.
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- 3,5-Bisoxygenated 2-(ω-halo-3-oxygenated-1-alkenyl)-cyclopentane-1-heptanoic acids and derivatives thereof
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3,5-Bisoxygenated 2-(ω-halo-3-oxygenated-1-alkenyl)-cyclopentane-1-heptanoic acids and derivatives thereof, conveniently obtained by processes utilizing 2-formyl-3-hydroxy-5-oxycyclopent-1-eneheptanoic acids as the starting materials, display valuable pharmacological properties, e.g. anti-fertility, bronchodilating, anti-secretory, smooth muscle stimulatory, and blood platelet aggregation-inhibiting.
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