ascorbic-acid and gulonic-acid

Tartaric acid has high economic value as an antioxidant and flavorant in food and wine industries. l-Tartaric acid biosynthesis in wine grape (

Topics: Aldo-Keto Reductases; Ascorbic Acid; Catalytic Domain; Glyoxylates; Plant Proteins; Pyruvic Acid; Substrate Specificity; Sugar Acids; Tartrates; Vitis

DFT calculations were carried out to investigate reaction paths of L-ascorbic acid (AAH2), hydroxyl radicals and water clusters. Frontier-orbital analyses were also performed to examine the regioselectivity of the OH˙ addition. Transition states of the electrolytic dissociation of AAH2 and intermediate carboxylic acids were found to have very small activation energies through proton transfers along hydrogen bonds. The ionized species (anions) are subject to the electrophilic attack of OH˙. The elementary processes of AAH2 → A˙(-) → dehydroascorbic acid → diketogulonic acid → threonic, oxalic, xylonic and lyxonic acids were investigated and discussed. The processes involved in the conversion of dehydroascorbic acid into a bicyclic hemiketal were also examined as a side-chain participating reaction. The oxidation and degradation of vitamin C up to threonic acid were described mainly as a donor (AAH2)-acceptor (OH˙) reaction.

Topics: Ascorbic Acid; Butyrates; Carbon Dioxide; Dehydroascorbic Acid; Free Radicals; Hydrogen Bonding; Models, Molecular; Molecular Conformation; Oxalic Acid; Oxidation-Reduction; Quantum Theory; Sugar Acids

The co-cultures of Ketogulonicigenium vulgare and Bacillus cereus were subcultured daily for a total of 150 transfers. The yield of 2-keto-gulonic acid (2-KGA) and medium pH in the co-cultures were measured. We found that the serial subcultivation increased the yield of 2-KGA from 77% (original co-culture) to 93% (the 150th transfer of transferred co-culture). The resulted strains are of industrial interests for vitamin C production.

Topics: Ascorbic Acid; Bacillus cereus; Biotechnology; Cell Culture Techniques; Fermentation; Rhodobacteraceae; Sorbose; Sugar Acids

In the present study, NMR-based urinary metabonomic profiles resulting from dosing with widely recognized microsomal enzyme inducers were evaluated in male rats. Wistar or Sprague-Dawley rats were dosed daily by oral gavage with phenobarbital (PB; 100 mg/kg), diallyl sulfide (DAS; 500 mg/kg), the investigational compound DMP-904 (150 mg/kg), or beta-naphthoflavone (BNF; 100 mg/kg) for 4 days, and urine was collected daily for analysis. Compounds known to increase cytochrome P450 2B enzymes, including PB, DAS and DMP-904, increased the urinary excretion of gulonic and ascorbic acid in a time-dependent manner, reaching a maximum following 3-4 days of dosing. In contrast, BNF, an agent that induces primarily Cyp1A enzymes, did not increase gulonic or ascorbic acid excretion, despite inducing Cyp1A1 more than 200-fold. Given the metabonomic results, hepatic transcriptional changes in the regulation of ascorbic acid biosynthesis were determined by RT-PCR. All Cyp2B inducers increased hepatic mRNA levels of aldo-keto reductase 1A1, an enzyme that catalyzes the formation of gulonic acid from glucuronate with concurrent decreased expression of both regucalcin (Rgn), the enzyme responsible for conversion of gulonic acid to gulono-1, 4-lactone and gulonolactone oxidase (Gulo), the rate-limiting enzyme in ascorbate biosynthesis. These effects would be expected to increase levels of gulonic acid. In addition, Cyp2B inducers also increased hepatic expression of enzymes regulating ascorbic acid reutilization including glutaredoxin reductase (Glrx2) and thioredoxin reductase (Txnrd1). In contrast, BNF did not effect hepatic expression of any enzyme regulating gulonic or ascorbic acid biosynthesis. Thus, some microsomal enzyme inducers alter transcriptional regulation of ascorbic acid biosynthesis, and these changes are detected by noninvasive metabonomic profiling. However, not all microsomal enzyme inducers appear to alter ascorbic acid metabolism. Finally, the work illustrates how metabonomic results can direct additional studies to determine the biochemical mechanisms underlying changes in urinary metabolite excretion.

Topics: Allyl Compounds; Animals; Ascorbic Acid; Cytochrome P-450 Enzyme System; Gene Expression Profiling; Liver; Magnetic Resonance Spectroscopy; Male; Metabolomics; Phenobarbital; Rats; Rats, Sprague-Dawley; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; Sugar Acids; Sulfides; Time Factors; Transcriptional Activation

We applied high-pressure liquid chromatography to assess the decomposition of the oxidized form of vitamin C, dehydro-L-ascorbic acid. We selected experimental conditions that might represent a wide variety of clinical and research procedures. Decay of dehydro-L-ascorbic acid proceeded much more rapidly at high pH (7-8) than at low pH (3-5) and was more rapid at 37 or 45 degrees C than at 0 or 23 degrees C. When evaluated at pH 6.6, the percent decay was somewhat more rapid from an initial concentration of 1000 mumol/L than at 5-10 mumol/L. The analytical procedure (HPLC) provided useful information about the rate of decay under various conditions. This may facilitate future biological and clinical studies that require a distinction between the oxidized and reduced forms of vitamin C.

Topics: Ascorbic Acid; Chromatography, High Pressure Liquid; Dehydroascorbic Acid; Drug Stability; Hydrogen-Ion Concentration; Oxidation-Reduction; Sugar Acids; Temperature

1. Urinary levels of xylitol and glucuronic, glucaric, gulonic and ascorbic acids were measured in the rat, rabbit, guinea-pig and marmoset by an improved g.l.c. technique. 2. Administration of a compound (2-methylbenzanilide) known to be conjugated and excreted as a beta-glucuronide had some effect on the output of these compounds of the glucuronic acid pathway in all four species, and caused a significant decrease in gulonic acid in the rat.

Topics: Animals; Ascorbic Acid; Callitrichinae; Chromatography, Gas; Female; Glucaric Acid; Glucuronates; Guinea Pigs; Haplorhini; Male; Rabbits; Rats; Species Specificity; Sugar Acids; Time Factors; Xylitol

1. The synthesis of ascorbic acid in rat-liver extracts is impaired during starvation, and more from glucuronolactone and glucuronate than from gulonate and gulonolactone. 2. The formation of xylulose from gulonate and from gulonolactone is greatly enhanced during starvation, whereas it is decreased from glucuronolactone and from glucuronate. 3. The activity of the enzymes of the glucuronic acid pathway during starvation has been determined in rat-liver preparations. Gulonolactone oxidase is decreased, NAD-linked gulonate dehydrogenase is enhanced, and uronolactonase, aldonolactonase and NADP-linked hexonate dehydrogenase are unchanged. 4. The impairment of ascorbic acid synthesis from gulonate observed during starvation can be accounted for by the depressed activity of gulonolactone oxidase. 5. The cause of the enhanced formation of xylulose has been located in the sedimentable fraction of liver homogenate. 6. The hypothesis is formulated of an increased utilization of the glucuronic acid pathway during starvation.

Topics: Alcohol Oxidoreductases; Ascorbic Acid; Carbohydrate Dehydrogenases; Carbohydrate Metabolism; Esterases; Glucuronates; Glucuronic Acid; Lactones; Liver; Liver Extracts; Metabolism; NADP; Oxidoreductases; Pentoses; Rats; Research; Starvation; Sugar Acids; Xylulose

1. The effect of starvation on the synthesis of ascorbic acid and of xylulose from glucuronolactone and from gulonate has been studied with liver extracts from cats, rabbits, hamsters, mice and guinea pigs. 2. The synthesis of ascorbic acid from glucuronolactone is decreased in all species except cats, and that from gulonate is decreased in hamsters and mice only. 3. The synthesis of xylulose from glucuronolactone was decreased in all species except cats and mice, whereas from gulonate it was enhanced in all the species examined.

Topics: Animals; Ascorbic Acid; Carbohydrate Metabolism; Cats; Cricetinae; Glucuronates; Guinea Pigs; Lactones; Liver; Liver Extracts; Metabolism; Mice; Pentoses; Rabbits; Research; Starvation; Sugar Acids; Xylulose

Topics: Ascorbic Acid; Carbohydrate Metabolism; Dietary Carbohydrates; Fasting; Liver; Metabolism; Pentoses; Rats; Research; Sugar Acids; Xylulose

Topics: Ascorbic Acid; Keto Acids; Sugar Acids

Topics: Animals; Ascorbic Acid; Barbital; Carbohydrate Metabolism; Galactose; Glucuronic Acid; Rats; Sugar Acids

Topics: Animals; Ascorbic Acid; Carbohydrate Metabolism; Hexoses; Liver; Rats; Sugar Acids

Topics: Ascorbic Acid; Caproates; Histocytochemistry; Sugar Acids

Topics: Ascorbic Acid; Carbohydrate Metabolism; Guinea Pigs; Sugar Acids

Topics: Ascorbic Acid; Hydrazines; Phenylhydrazines; Sugar Acids; Tissue Extracts

Topics: Ascorbic Acid; Sugar Acids