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Patent 6,420,420 This invention provides a method for increasing the ascorbic acid concentration in brain tissues of a subject which comprises administering to the subject an amount of dehydroascorbic acid effective to increase the concentration of ascorbic acid in brain tissues. It is the intention of this invention to administer the dehydroascorbic acid in a stabilized form. Finally, appropriate amounts of ascorbic acid and ascorbate oxidase may be administered together to a subject to produce an amount of dehydroascorbic acid effective to increase the concentration of ascorbic acid in the brain tissues of the subject. www.pharmcast.com /Patents/Yr2002/July2002/071602/6420420_Ascorbic071602.htm   (1275 words)

Intracellular Accumulation of Ascorbic Acid Is Inhibited by Flavonoids via Blocking of Dehydroascorbic Acid and ...   (Site not responding. Last check: 2007-10-31) Analyses of the inhibition of the dehydroascorbic acid and ascorbic acid Dehydroascorbic acid uptake (150 µmol/L) was inhibited by flavonoids: myricetin, quercetin, fisetin, apigenin, hesperetin, naringenin and catechin. for dehydroascorbic acid and ascorbic acid uptake in vitro. www.nutrition.org /cgi/content/full/130/5/1297   (3602 words)

Accumulation of Vitamin C (Ascorbate) and Its Oxidized Metabolite Dehydroascorbic Acid Occurs by Separate Mechanisms -- ... Dehydroascorbic acid was proposed to be transported by a glucose transporter (12, 13, 14, 15), which was identified as GLUT I expressed in Xenopus laevis oocytes (15). In contrast to ascorbate, dehydroascorbic acid transport and intracellular reduction in neutrophils is sodium-independent (11). Dehydroascorbic acid reduction in neutrophil homogenates was similar to that expected from the same number of whole cells, was localized to cytosol, was dependent on cell number, was non-dialyzable, and was found in the retentate using centrifugal ultrafiltration (data not shown). www.jbc.org /cgi/content/full/270/21/12584   (5433 words)

Resolution of the Facilitated Transport of Dehydroascorbic Acid from Its Intracellular Accumulation as Ascorbic Acid -- ... The oxidation of ascorbic acid to dehydroascorbic acid appears to be part of the mechanism by which cells of the host defense system, such as neutrophils, increase their uptake of dehydroascorbic acid when activated by physiological stimuli. Kinetic analysis of the uptake of ascorbic acid in human neutrophils has revealed the presence of two functional activities with different affinities for ascorbate, an observation that was interpreted as suggesting the existence of at least two separate transport systems involved in the cellular uptake of ascorbic acid(27). Competition experiments showed that the transport of dehydroascorbic acid was inhibited by methylglucose and deoxyglucose, and the specificity of this inhibition was demonstrated by the results indicating that other sugars unable to interact with the glucose transporters had no effect on the transport of dehydroascorbic acid. www.jbc.org /cgi/content/full/270/40/23706   (7330 words)

Vitamin C Crosses the Blood-Brain Barrier in the Oxidized Form Through the Glucose Transporters -- Agus et al. 100 ... Dehydroascorbic acid is transported across the blood-brain barrier and accumulates in the brain as ascorbic acid. and was responsible for the dehydroascorbic acid transport. Mendiratta, K.E. Hill, and R.F. Burk (1997) Reduction of dehydroascorbate to ascorbate by the selenoenzyme thioredoxin reductase. www.jci.org /cgi/content/full/100/11/2842   (4547 words)

Lipoic Acid The alpha-lipoic acid dependent reduction was stimulated by factors that increased the NADH dependent reduction of alpha-lipoic acid to dihydrolipoic acid in coupled reactions. A moderate correlation between the increase in blood alpha-lipoic acid concentration in patients with the liver diseases during the replacement therapy with alpha-lipoic acid drugs and a number of parameters of thrombelastogram was established. Influence of alpha-lipoic acid on intracellular glutathione in vitro and in vivo. www.cfsn.com /lipoic.html   (3256 words)

Vitamin C Ascorbic acid is a cofactor for crucial reactions in the carnitine biosynthetic pathway. Dietary dehydroascorbic acid is absorbed from the lumen of the small intestine into the enterocytes in such a manner. All dehydroascorbic acid within the enterocytes is reduced to ascorbic acid via reduced glutathione, and ascorbic acid leaves the enterocytes to enter, first, the portal and, subsequently, the systemic circulation. www.pdrhealth.com /drug_info/nmdrugprofiles/nutsupdrugs/vit_0264.shtml   (8600 words)

Vitamin C Shown To Cross The Blood Brain Barrier   (Site not responding. Last check: 2007-10-31) Agus, Golde and their colleagues reasoned that vitamin C would cross the blood brain barrier as dehydroascorbic acid via the same glucose transport mechanism and be retained as ascorbic acid in the brain. To find out, mice were injected with either ascorbic acid, dehydroascorbic acid, or sucrose (as a measure of blood volume) and their brains were subsequently analyzed at varying time intervals for vitamin C content. The researchers found that ascorbic acid was not able to cross the blood brain barrier, while dehydroascorbic acid readily entered the brain and was retained in the tissue as ascorbic acid. www.pslgroup.com /dg/4a3a2.htm   (633 words)

Stromal Cell Oxidation: A Mechanism by Which Tumors Obtain Vitamin C -- Agus et al. 59 (18): 4555 -- Cancer Research   (Site not responding. Last check: 2007-10-31) acid was inhibited by coadministration of superoxide dismutase, C]ascorbic acid both entered the tumor xenografts and the accumulation of ascorbic acid, by the xenografts, was blocked by coinjected SOD and not by catalase or saline. Ascorbic acid, the predominant form of vitamin C in blood, is oxidized to dehydroascorbic acid in the tumor microenvironment by superoxide anion. cancerres.aacrjournals.org /cgi/content/full/59/18/4555   (3154 words)

Food & Nutrition Information The catecholamines dopamine, norepinephrine, and epinephrine are synthesized from the amino acid tyrosine. Ascorbic acid was accumulated against a concentration gradient in neutrophils; extracellular ascorbate in micromolar concentration was accumulated in millimolar concentrations by a high and a low affinity transport activity. Dehydroascorbic acid in micromolar or sub-micromolar concentration preferentially enters neutrophils and is immediately reduced back to ascorbic acid; the result is accelerated accumulation of ascorbate. www.healthyeatingclub.com /APJCN/Volume2/vol2supp/levine.htm   (6118 words)

Research Resources, Inc. - dough improver - bread - breadmaking chemistry - bromate replacer - fermentation   (Site not responding. Last check: 2007-10-31) The ability of food acids to form chelates is used to slow down the oxidation of ascorbic acid to dehydroascorbic acid in dough. Lastly, the experimental facts also establish that the use of ascorbic acid combined with effective amounts of effective food acid produces the properly oxidized dough (i.e., actually properly developed dough structure of proteins) that is strengthened and stabilized by inter- and/or intramolecular bonds during mixing, proofing and baking. Ascorbic acid is oxidized to form dehydroascorbic acid by enzyme and copper-catalyzed oxidation during dough mixing process. www.rrkim.com   (5798 words)

Synergism   (Site not responding. Last check: 2007-10-31) Each mole of ascorbic acid can reduce two moles of silver bromide to two moles of silver and 2 moles of hydrobromic acid, forining 1 mole of dehydroascorbic acid in the process. In this case one molecule of chlorine and one of ascorbic acid combine to form two molecules of hydrochloric acid and one of dehydroascorbic acid. In a split stock formulation where phenidone and ascorbic acid are kept in one of the solutions the aerial oxidation of this solution can still take place, but the change in pH of this solution due to the formation of dehydroascorbic acid will be small, especially if chlorinated and fluorinated water are avoided. unblinkingeye.com /Articles/Synergism/synergism.html   (1647 words)

Getting Vitamin C On The Brain Ascorbic acid, the form of vitamin C absorbed from the intestines, is unable to cross the blood brain barrier. However, Agus and colleagues found that when ascorbic acid was converted to dehydroascorbic acid it could be ferried across the blood brain barrier by a transporter molecule. In the case of dehydroascorbic acid it was the GLUT1, which normally transports glucose, that moved the vitamin. www.personalmd.com /news/a1997120101.shtml   (305 words)

Vitamin C Shown To Cross The Blood Brain Barrier Agus, Golde and their colleagues reasoned that vitamin C would cross the blood brain barrier as dehydroascorbic acid via the same glucose transport mechanism and be retained as ascorbic acid in the brain. To find out, mice were injected with either ascorbic acid, dehydroascorbic acid, or sucrose (as a measure of blood volume) and their brains were subsequently analyzed at varying time intervals for vitamin C content. The researchers found that ascorbic acid was not able to cross the blood brain barrier, while dehydroascorbic acid readily entered the brain and was retained in the tissue as ascorbic acid. www.docguide.com /dg.nsf/PrintPrint/0EA2EA059F21608D8525656000536B79   (649 words)

Research and Reviews: Dairy, Special Circular 182-01 The concentrations of sixteen carbon fatty acids were negatively correlated with milk flavor but those relationships were probably indirect since concentrations of polyunsaturated fatty acids were negatively correlated with 16-carbon fatty acids. The polyunsaturated index is the concentration of polyunsaturated fatty acids weighted by the number of oxidizable chemical bonds in the molecule. Dehydroascorbic acid is a breakdown product of vitamin C and the positive coefficient for dehydroascorbic acid in the equations suggest that increased breakdown of vitamin C is related to oxidized flavor. ohioline.osu.edu /sc182/sc182_8b.html   (740 words)

Preservation of Ascorbate Developers   (Site not responding. Last check: 2007-10-31) Dehydroascorbic acid in the body has a half life of about 6 minutes. The dehydroascorbic acid that forms in an acidic stock solution may keep for a long time, but it will begin to decompose as soon as the working solution is prepared, due to the increased pH. Supposing that 1 mole of oxidized ascorbic acid can reduce 1 mole of phenidone, a stock solution of 40 grams ascorbic acid and 1 gram phenidone would be reduced to about 1/5 of its original strength after oxidation of 1/40 of the ascorbic acid. unblinkingeye.com /Articles/Preserv/preserv.html   (1144 words)

Vitamin C - ascorbic acid information page. All about vitamin C (also known as ascorbic acid) and the role it plays in ... Vitamin C also known as, ascorbic acid, L-ascorbic acid, dehydroascorbic acid, the antiscorbutic vitamin, L-xyloascorbic acid and L-threo-hex-2-uronic acidy-lactone, is a much talked about vitamin, with people claiming it as a cure-all for may diseases and problems - from cancer to the common cold. Vitamin C is required in the synthesis of collagen in connective tissue, neurotransmitters, steroid hormones, carnitine, conversion of cholesterol to bile acids and enhances iron bioavailability. Since ascorbic acid is a water-soluble vitamin, toxic levels are not built up or stored in the body, and any excess is lost mostly through urine. www.anyvitamins.com /vitamin-c-ascorbicacid-info.htm   (881 words)

Ascorbate recycling in human neutrophils: Induction by bacteria -- Wang et al. 94 (25): 13816 -- Proceedings of the ... acid to ascorbate, ascorbate recycling was absent because of negligible Ascorbate and dehydroascorbic acid were measured as described by HPLC with coulometric electrochemical detection or by scintillation dehydroascorbic acid transport is mediated by glucose transporters www.pnas.org /cgi/content/full/94/25/13816   (2606 words)

319. Bromophos-ethyl (WHO Pesticide Residues Series 5) Serum ascorbic acid levels, and urine ascorbic acid and dehydroascorbic acids levels measured at 0, 1, 2, 4, 5 and 9 weeks after initiation of the study were normal at all time intervals. Serum ascorbic acid levels and urine ascorbic acid and dehydroascorbic acid levels, measured at 0, 1, 2, 4, 5 and 9 weeks after initiation of the study were normal. Studies in rats and dogs showed an increase in urinary excretion of ascorbic acid and dehydroascorbic acid in two year rat and dog studies as well as shorter-term studies in both species. www.inchem.org /documents/jmpr/jmpmono/v075pr06.htm   (1880 words)

Vitamin C; Ascorbic Acid; References   (Site not responding. Last check: 2007-10-31) Plasma concentrations of the antioxidant vitamin ascorbic acid were measured by high-performance liquid chromatography in critically ill patients in whom the excessive generation of reactive oxygen species could compromise antioxidant defense mechanisms. Median concentrations of both total vitamin C (ascorbic acid and dehydroascorbic acid) and ascorbic acid in these patients were < 25% (P < 0.001) of the values found in healthy control subjects and in subjects in two other disease groups (diabetes, gastritis) in which reactive oxygen species are reported to be increased. The objective of this study was to evaluate the antioxidative properties of the multivitamin cocktail Omnibionta (alpha-tocopherol, ascorbic acid, retinol, vitamin B complex) in terms of diminishing lipid peroxidation with improvement of leg edema performance after limb revascularization operations in humans. www.nutramed.com /nutrition/vitamincref.htm   (12763 words)

Le Magazine, February 2005 - Report: R-Dihydro-Lipoic Acid By 1988, alpha-lipoic acid had been revealed as a powerful biological antioxidant, exhibiting a potential to quench free radicals equal to that of coenzyme Q10 (CoQ10) and vitamins C and E. Researchers also discovered that alpha-lipoic acid is unique in being the only antioxidant known to work in both fat- and water-soluble tissues. To understand how alpha-lipoic acid and R-dihydro-lipoic acid work against various degenerative disorders, it is first necessary to understand how these compounds work in the body—specifically, how they interact chemically with other critical antioxidants such as glutathione and vitamins C and E to combat harmful reactive oxygen species. Alpha-lipoic acid has been shown to be particularly helpful for conditions arising from diabetes, and has been used in Europe for over 30 years for diabetic complications caused by overproduction of reactive oxygen species and nitrogen radicals. www.lef.org /magazine/mag2005/feb2005_report_lipoic_01.htm   (2018 words)

[Frontiers in Bioscience 3, d1-10, January 1, 1998] Evans, R. Currie, and A. Campbell: The distribution of ascorbic acid between various cellular components of blood, in normal individuals, and its relation to the plasma concentration. Dhariwal, K. Hartzell, and M. Levine: Ascorbic acid and dehydroascorbic acid measurements in human plasma and serum. Borsook, H., H. Davenport, C. Jeffreys, and R. Warner: The oxidation of ascorbic acid and its reduction in vitro and in vivo. www.bioscience.org /1998/v3/d/may/9.htm   (2088 words)

Dehydroascorbic acid and oxidative stress in haemodialysis patients -- Nakayama et al. 16 (3): 574 -- Nephrology ... Dehydroascorbic acid and oxidative stress in haemodialysis patients -- Nakayama et al. Dehydroascorbic acid and oxidative stress in haemodialysis patients acid fraction, may be a measure of oxidative stress during haemodialysis. ndt.oxfordjournals.org /cgi/content/abstract/16/3/574   (415 words)

Effect of monosaccharide on dehydroascorbic acid uptake by placental membrane vesicles -- Ingermann et al. 67 (2): 389 ... Effect of monosaccharide on dehydroascorbic acid uptake by placental membrane vesicles -- Ingermann et al. Effect of monosaccharide on dehydroascorbic acid uptake by placental membrane vesicles Dehydroascorbic acid (DHA), the oxidized form of vitamin C, is transported jcem.endojournals.org /cgi/content/abstract/67/2/389   (207 words)

Hormone-Regulated and Glucose-Sensitive Transport of Dehydroascorbic Acid in Immature Rat Granulosa Cells -- Kodaman ... Hormone-Regulated and Glucose-Sensitive Transport of Dehydroascorbic Acid in Immature Rat Granulosa Cells -- Kodaman and Behrman 140 (8): 3659 -- Endocrinology Hormone-Regulated and Glucose-Sensitive Transport of Dehydroascorbic Acid in Immature Rat Granulosa Cells Ascorbic acid is concentrated in granulosa cells of the follicle, endo.endojournals.org /cgi/content/abstract/140/8/3659   (423 words)

Age-associated decline in ascorbic acid concentration, recycling, and biosynthesis in rat hepatocytes—reversal with ... Age-associated decline in ascorbic acid concentration, recycling, and biosynthesis in rat hepatocytes—reversal with (R)-{alpha}-lipoic acid supplementation -- Lykkesfeldt et al. Ascorbic acid recycling from dehydroascorbic acid and biosynthesis Packer, L. (1994) Antioxidant properties of lipoic acid and its therapeutic effects in prevention of diabetes complications and cataracts. www.fasebj.org /cgi/content/full/12/12/1183   (4564 words)

Hormone-Regulated and Glucose-Sensitive Transport of Dehydroascorbic Acid in Immature Rat Granulosa Cells -- Kodaman ... to ascorbic acid, DHAA is irreversibly degraded to 2,3-diketogulonic Dehydroascorbic acid and its metabolites were separated on a Phase Kodaman PH, Aten RF, Behrman HR 1998 Accumulation of ascorbate by endocrine-regulated and glucose-sensitive transport of dehydroascorbic acid in luteinized rat ovarian cells. endo.endojournals.org /cgi/content/full/140/8/3659   (4441 words)

Ascorbic and dehydroascorbic acids measured in plasma preserved with dithiothreitol or metaphosphoric acid -- Margolis ... Ascorbic and dehydroascorbic acids measured in plasma preserved with dithiothreitol or metaphosphoric acid -- Margolis et al. Ascorbic and dehydroascorbic acids measured in plasma preserved with dithiothreitol or metaphosphoric acid the measurement of ascorbic acid and dehydroascorbic acid. www.clinchem.org /cgi/content/abstract/36/10/1750   (286 words)

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