ascorbic-acid and isoascorbic-acid

Erythorbic acid, a stereoisomer of ascorbic acid with similar physicochemical properties, is widely used as an antioxidant in processed foods.. The aims of the present study were to evaluate the effect of erythorbic acid on iron absorption from ferrous sulfate at molar ratios of 2:1 and 4:1 (relative to iron) and to compare the effect of erythorbic acid directly with that of ascorbic acid at a molar ratio of 4:1.. Iron absorption from iron-fortified cereal was measured in 10 women on the basis of erythrocyte incorporation of stable iron isotopes ((57)Fe or (58)Fe) 14 d after administration. Each woman consumed 4 ferrous-sulfate-fortified test meals (containing 5 mg Fe/meal) with or without added erythorbic or ascorbic acid. The data were evaluated by use of paired t tests, and the results are presented as geometric means.. Iron absorption from the test meal without any added enhancer was 4.1%. The addition of erythorbic acid (at molar ratios of 2:1 and 4:1 relative to iron) increased iron absorption 2.6-fold (10.8%; P < 0.0001) and 4.6-fold (18.8%; P < 0.0001), respectively. The addition of ascorbic acid (molar ratio of 4:1) increased iron absorption 2.9-fold (11.7%; P = 0.0004). At a molar ratio of 4:1, erythorbic acid was 1.6-fold (P = 0.0002) as potent an enhancer of iron absorption as was ascorbic acid.. Although erythorbic acid is a potent enhancer of iron absorption, its lack of antiscorbutic activity limits its usefulness in iron-fortification programs. However, it may play a major role in enhancing iron bioavailability from mixed diets that include foods preserved with erythorbic acid.

Topics: Adult; Ascorbic Acid; Edible Grain; Female; Food, Fortified; Humans; Intestinal Absorption; Iron; Stereoisomerism

Considerable evidence exists that smoking significantly lowers the concentration of plasma antioxidants. While for most antioxidants this effect appears to result mainly from altered dietary habits, ascorbic acid has recently been shown to be depleted by smoking per se. However, the direct cause of ascorbate depletion remains unclear. Erythorbic acid is a stereoisomer of ascorbic acid commonly used as antioxidant in foodstuffs and has the same redox properties as ascorbic acid. We therefore investigated if erythorbic acid could be used as a non-isotopic marker of smoking-induced oxidative stress. In a sample of smokers (n 10) and non-smokers (n 10), the pharmacokinetics of erythorbic acid were followed after a single oral dose (1 g) and subsequently, the effect of a 2-week ascorbic acid supplementation (0.5 g/d) on erythorbic acid kinetics was studied in a double-blind, placebo-controlled fashion. There were no significant effects of smoking or supplementation on relative bioavailability (difference in area under curve, AUC 0-infinity) of erythorbic acid (smokers 357 (sd 119), non-smokers 414 (sd 142) micromol.h/l; P=0.34). Time to reach maximum plasma concentration (Tmax) was significantly less in smokers (P=0.03). If the relative pharmacokinetics of erythorbic acid between smokers and non-smokers compares with those of AA, our present results do not suggest that altered pharmacokinetics is likely to play a major role in the ascorbic acid depletion consistently observed in smokers.

Topics: Adult; Analysis of Variance; Antioxidants; Area Under Curve; Ascorbic Acid; Biological Availability; Biomarkers; Double-Blind Method; Humans; Male; Middle Aged; Oxidative Stress; Smoking

Erythorbic acid, an epimer of L-ascorbic acid, is used in the United States as a food additive. Studies were conducted to determine whether the ingestion of erythorbic acid in the diet had any beneficial or adverse effects on the human requirement for vitamin C. Young women were fed diets that contained controlled amounts of erythorbic acid and ascorbic acid. In pharmacokinetic evaluations, erythorbic acid and ascorbic acid were rapidly absorbed with little interaction. Erythorbic acid cleared from the body more rapidly than ascorbic acid. Some subjects received diets deficient in vitamin C for periods < or = 30 d. Increasing intakes of erythorbic acid or prolonged intakes of < or = 1 g erythorbic acid/d did not indicate any interactions with ascorbic acid. Consumption of erythorbic acid resulted in the presence of erythorbic acid in mononuclear leukocytes. Ascorbic acid concentrations in these cells were not affected by the presence of erythorbic acid. Erythorbic acid disappeared quickly from these cells with cessation of erythorbic acid supplements. Prolonged ingestion of erythrobic acid by young women neither antagonized nor spared their vitamin C status.

Topics: Absorption; Adult; Ascorbic Acid; Chromatography, High Pressure Liquid; Drug Combinations; Female; Humans; Osmolar Concentration; Stereoisomerism; Treatment Outcome

The Expert Panel for Cosmetic Ingredient Safety reviewed newly available studies since their original assessment in 1999, along with updated information regarding product types and concentrations of use, and confirmed that Erythorbic Acid and Sodium Erythorbate are safe as cosmetic ingredients in the practices of use and concentration as described in this report.

Topics: Ascorbic Acid; Consumer Product Safety; Cosmetics

The current trends among consumers are pushing for the use of natural antioxidants options. Açaí fruit is rich on polyphenolic components but no studies have been carried out to evaluate their effect in meat products. The objective was to investigate the effect of açaí extract on refrigerated pork patties quality. Five treatments were done: without antioxidant (CON), Sodium Erythorbate 500 mg.kg

Topics: Animals; Antioxidants; Ascorbic Acid; Color; Euterpe; Food Storage; Meat Products; Plant Extracts; Powders; Swine

Root canal therapy is the most effective and common method for pulpitis and periapical periodontitis. During the root canal preparation, chemical irrigation plays a key role. However, sodium hypochlorite (NaOCl), the widely used irrigation fluid, may impact the bonding strength between dentin and restorative material meanwhile sterilization and dissolving. Therefore, it's important to explore the influence of NaOCl on the adhesion between dentin and restoration materials to ensure clinical efficacy. This study aims to explore the effect of NaOCl on dentine adhesion and evaluate the effect of dentine adhesion induced by sodium erythorbate (ERY), and to provide clinical guidance on dentin bonding after root canal therapy.. Seventy freshly complete extracted human third molars aged 18-33 years old, without caries and restorations were selected. A diamond saw was used under running water to achieve dentine fragments which were divided into 10 groups with 14 fragments in each group: 2 control [deionized water (DW)±10% ERY] and 8 experimental groups (0.5%, 1%, 2.5%, and 5.25% NaOCl±10% ERY). The dentine specimens in the control group (treated with DW) and the experimental groups (treated with 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl) were immersed for 20 min using corresponding solutions which were renewed every 5 min. The other 5 groups were immersed in 10% ERY for 5 min after an initial washing with DW for 1 min. Then, we selected 4 dentine fragments from all 14 fragments in each group and the numbers and diameters of opening dentinal tubules were observed under scanning electron microscope (SEM). The other 10 dentine fragments from each group were used to make adhesive samples by using self-etch adhesive wand composite resin. All the above adhesive samples were sectioned perpendicular to the bonded interface into 20 slabs with a cross-sectional area of 1 mm×1 mm using a diamond saw under the cooling water, and then the morphology of 10 slabs in each group's bonding interface was observed from aspects of formation of resin tags, depth of tags in dentin, and formation of hybrid layer under SEM. The other 10 slabs of each group's microtensile bond strength and failure modes were also analyzed.. Among the 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl groups, the number and diameter of patent dentinal tubules gradually increased with the rise of concentration of NaOCl solution (all. The bonding strength to dentine increases with the increase of NaOCl concentration when the concentration lower than 2.5%; whereas it is decreased at a higher concentration (such as 5.25%). 10% ERY has a definite recovery effect on attenuated bonding strength to 5.25% NaOCl-treated dentine.

Topics: Adolescent; Adult; Ascorbic Acid; Dental Bonding; Dentin; Dentin-Bonding Agents; Diamond; Humans; Materials Testing; Microscopy, Electron, Scanning; Resin Cements; Sodium Hypochlorite; Tensile Strength; Water; Young Adult

Topics: Animals; Antioxidants; Ascorbic Acid; Cactaceae; Color; Cooking; Meat Products; Plant Extracts; Swine; Thiobarbituric Acid Reactive Substances

The effect of pH and ionic strength (μ) on the extraction capacity of myofibrillar proteins from Jumbo squid mantle muscle along with the addition of isoascorbic acid (IA) in its gel-forming ability (GFA) were evaluated. The results indicate that μ had a greater impact (p < 0.05) than pH on the extraction of muscle myofibrillar proteins. The effectiveness of IA, as the precursor of dehydro-isoascorbic acid (DIA), on the oxidation of sulfhydryl groups (-SH) to disulfide bonds (-SS-) of extracted proteins at 0.6 μ was also evaluated. During the sol-gel transition the -SH groups initially present in the protein system decreased (p < 0.05) due to the combined effect of heat treatment (90 °C/30 min) and the addition of IA; however, the oxidative effect of IA reduced (p < 0.05) the GFA of Jumbo squid muscle proteins. Results also indicated that NaCl at 2.8% rather than at 2.5% during gel preparation significantly (p < 0.05) improves its GFA.

Topics: Animals; Ascorbic Acid; Decapodiformes; Disulfides; Gels; Hydrogen-Ion Concentration; Muscle Proteins; Muscles; Osmolar Concentration; Solubility

Erythorbyl myristate (EM), a potential multi-functional food emulsifier, was newly synthesized by immobilized lipase-catalyzed esterification between antioxidative erythorbic acid and antibacterial myristic acid. The yield and productivity of EM were 56.13 ± 2.51 mg EM/g myristic acid and 1.76 ± 0.08 mM/h, respectively. The molecular structure of EM was identified as (R)-2-((R)-3,4-dihydroxy-5-oxo-2,5-dihydrofuran-2-yl)-2-hydroxyethyl tetradecanoate using HPLC-ESI/MS and 2D [

Topics: Anti-Bacterial Agents; Antioxidants; Ascorbic Acid; Chromatography, High Pressure Liquid; Emulsifying Agents; Esterification; Food Microbiology; Functional Food; Lipase; Magnetic Resonance Spectroscopy; Microbial Sensitivity Tests; Molecular Structure; Myristic Acid; Spectrometry, Mass, Electrospray Ionization; Stereoisomerism; Thermodynamics

Pork is used as raw material to produce Cantonese sausage, and 0.5 or 1 g kg. It was found that d-sodium erythorbate significantly reduced the free radical content and myoglobin and lipid oxidation rates and increased heme iron levels. When d-sodium erythorbate was added to the sausage, the absorption peak of myoglobin porphyrin shifted left, migrating from 414 to 405 nm. At 72 h, with an increase in the d-sodium erythorbate content, a significant negative correlation was identified between heme iron and the degree of redness (P < 0.01).. During sausage processing, there are strong correlations among TBARS values, free radical content, metmyoglobin levels, heme iron levels, a* and pH at the same d-sodium erythorbate level. At the same processing time, adding d-sodium erythorbate can slow the rate of myoglobin and lipid oxidation and prevent the discoloration of sausage. © 2019 Society of Chemical Industry.

Topics: Animals; Ascorbic Acid; Color; Food Additives; Food Handling; Lipids; Meat Products; Metmyoglobin; Myoglobin; Oxidation-Reduction; Swine

Topics: Antioxidants; Ascorbic Acid; Food Microbiology; Food Preservatives; Hydroxylamines; Lactobacillus delbrueckii; Meat Products; Mutagens; Nitriles; Pyrroles; Sodium Nitrite; Sorbic Acid

This study aimed to evaluate the shelf-life of mechanically filleted well-fed Atlantic mackerel during frozen storage at -25 °C and effect of treatment with antioxidants (sodium erythorbate and a polyphosphate mixture) and different antioxidant application methods (dipping, spraying and glazing). Both physicochemical measurements and sensory analysis were applied. Antioxidant treatments prolonged shelf-life of mackerel. Sensory analysis indicated that untreated fillets had a shelf-life of less than 2.5 months, while all antioxidant treated fillets exceeded that. The most effective treatment, dipping fillets into a sodium erythorbate solution, yielding a shelf-life of 15 months. Physicochemical methods used to evaluate degradation of lipids in the fillets were free fatty acids (FFA), lipid hydroperoxides (PV) and thiobarbituric acid reactive substances (TBARS). They did not correlate with sensory results and might therefore be a questionable choice for evaluation of oxidation and development of rancid flavour and odour in complex matrixes such as Atlantic mackerel.

Topics: Animals; Antioxidants; Ascorbic Acid; Fatty Acids; Fish Products; Food Storage; Freezing; Humans; Lipids; Oxidation-Reduction; Perciformes; Polyphosphates; Taste; Thiobarbituric Acid Reactive Substances; Time Factors

Eutectic freeze crystallization was developed to recover sodium erythorbate (NaE) from wastewater at pHs 4.1, 5.3, and 6.5. Two substances (A and B) were sequentially recovered from the samples. The recovery rate of substance A was 2.06, 1.83, and 3.03 g/L at pHs 4.1, 5.3, and 6.5, respectively; while that of B was 5.51, 3.09, and 3.26 g/L at the corresponding pHs. The analysis results of the two recovered substances indicated that substance A was mostly Na

Topics: Ascorbic Acid; Crystallization; Freezing; Hydrogen-Ion Concentration; Ice; Time Factors; Wastewater; Water Pollutants, Chemical; Water Purification

The effect of oil-soluble rosemary extract, sodium erythorbate and their mixture, and the influence of packaging method (air and vacuum packaging) on the quality of cooked turkey meatballs stored at -20 ℃ was determined. The smallest changes in malondialdehyde content were observed in samples with the addition of the natural antioxidant regardless of the packaging method. The mixture of synthetic and natural antioxidants was more effective in retarding lipid oxidation than the synthetic antioxidant, and more desirable results were observed in vacuum-packaged samples than in air-packaged samples. The samples with the addition of oil-soluble rosemary extract were characterised by lower intensity of red colour, but this parameter was more stable during frozen storage. The results of a sensory analysis revealed that the application of oil-soluble rosemary extract with or without sodium erythorbate significantly inhibited the development of warmed-over flavour in cooked poultry products.

Topics: Animals; Antioxidants; Ascorbic Acid; Color; Food Packaging; Food Quality; Food Storage; Freezing; Humans; Hydrogen-Ion Concentration; Lipid Peroxidation; Plant Extracts; Poultry Products; Rosmarinus; Taste; Turkeys

Peach slices were blanched (BL), vacuum infiltrated with D-sodium erythorbate (SE), predehydrated, and then nitrogen packaged (NP) before freezing to improve their quality. Our results showed that the BL, SE, and NP pretreatments remarkably improved the quality of frozen peaches. Frozen peaches pretreated by SE+NP+BL showed the highest total phenolic content (TPC), total antioxidant capacity (TAC), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity after thawing at 20°C for 24 hr. The soluble solids content and firmness of low-maturity peaches dehydrated to 25% dehydration of their weight were 11.1% and 211.2% higher than those of the control samples, respectively, while their drip loss was 71.9% lower than that of the controls. In conclusion, pretreatment by BL, predehydration, SE, and NP before freezing can significantly improve the quality of frozen peaches after thawing. PRACTICAL APPLICATIONS: We believe that our study results have practical applications because the method of vacuum dehydration combined with blanching, nitrogen packaging, and D-sodium erythorbate treatment of peaches maintains their original taste, inhibits color change, and decreases drip loss. This method is suitable for fruit frozen and stored at a commercial freezing temperature of -20°C and does not need advanced equipment or technology. It can be easily carried out during the fruit freezing process and can be applied to other frozen stored fruits besides peaches.

Topics: Ascorbic Acid; Dehydration; Food Packaging; Food Preservation; Food Storage; Freezing; Nitrogen; Prunus persica; Vacuum

This research was to compare mortadella elaborated with synthetic antioxidant and microcrystals of curcumin in relation to its physicochemical and sensorial characteristics for a period of 90 days. It was detect no differences between the three evaluated treatments in relation to the pH, color, and texture profile features. The mortadella with curcumin microcrystals showed significantly lower TBARS values at the end of the storage when compared to the other treatments. In the sensory analysis, the addition of curcumin decreased the acceptance of color's sample and the purchase intention, but no significant difference was observed among the other attributes. The color of the sample containing curcumin also became worse than its day-of-production standard during storage. The results obtained suggest the potential of curcumin in replacing synthetic antioxidants in cooked meat sausage, since it practically does not modify its physicochemical characteristics, besides preventing the oxidation of the food.

Topics: Antioxidants; Ascorbic Acid; Color; Consumer Behavior; Cooking; Curcumin; Food Storage; Humans; Hydrogen-Ion Concentration; Meat Products

The aim of this study was to assess the stability of sheep sausages with the addition of different concentrations of Origanum vulgare extract during storage. Five treatments were prepared: without natural antioxidant (control), sodium erythorbate 500mg/kg (ER), and three amounts of extract (N1=4964.51mg/kg, N2=6630.98mg/kg and N3=8038.20mg/kg). From appearance sensory analysis, control treatment differed significantly compared to ER (P<0.05) and N3 (P<0.01) groups, with intense red color, agreeing with trend of a* values. On the other hand, oregano extract improved the lipid and protein stability of cooked sausages during the storage time. Regarding volatile compounds from lipid oxidation, the N2 group presented the lowest values at the end of chilled period. In conclusion, the oregano extract showed antioxidant potential equivalent to sodium erythorbate at intermediate and high levels, calculated by DPPH

Topics: Animals; Antioxidants; Ascorbic Acid; Color; Cooking; Food Storage; Lipid Peroxidation; Meat Products; Origanum; Plant Extracts; Sheep

An activatable fluorescence monitoring platform based on a novel Maillard reaction product from d-glucose and L-arginine was prepared through a facile one-pot approach and applied for simultaneous detection of d-isoascorbic acid and tartaric acid. In this work, the new Maillard reaction product GLA was first obtained, and its fluorescence intensity can be effectively quenched by KMnO

Topics: Ascorbic Acid; Fluorescent Dyes; Hydrogen-Ion Concentration; Limit of Detection; Maillard Reaction; Potassium Permanganate; Spectrometry, Fluorescence; Tartrates

A simple enzyme-based nanohybrid material was fabricated via immobilizing ascorbic acid oxidase (AO) on the surface of flower-like electrodeposited gold nanoparticles (dpAu) and reduced graphene oxide (rGO) modified glassy carbon electrodes (GCEs). The composite material was used for stereoselective interaction with ascorbic acid (AA) and isoascorbic acid (IAA). Herein, AO was applied as a stereoselective selector, and the dpAu/rGO nanohybrid not only acted as a supporter for high loading of AO, but also served as the nanomaterial for signal amplification. The results showed obvious peak current differences between AA and IAA, indicating that this strategy could be employed to recognize AA and IAA. Under the optimum conditions, the sensor exhibited a good linear response to AA and IAA in a linear range of 1.0 × 10

Topics: Ascorbate Oxidase; Ascorbic Acid; Biosensing Techniques; Electrochemistry; Electroplating; Enzymes, Immobilized; Gold; Graphite; Metal Nanoparticles; Models, Molecular; Molecular Conformation; Oxides; Stereoisomerism; Substrate Specificity

Analysis of L-ascorbic acid (AsA) and erythorbic acid (ErA) in foods is generally performed by HPLC measurement after extraction with metaphosphoric acid solution. But this method can not always measure the concentrations of AsA and ErA precisely due to the presence of interfering compounds, and the reproducibility of retention time is poor. We considered that quantitative analysis by HPLC and confirmation by LC-MS/MS using an identical extraction solvent might be an effective approach for AsA and ErA analysis. Chelate fiber was added to the sample, followed by extraction with acetic acid solution containing ethylenediaminetetraacetic acid disodium salt, purification with Oasis MCX, and 2-fold dilution with methanol. The resulting solution was used for quantification by HPLC using a ZIC-HILIC column and identification by LC-MS/MS. In recovery tests with 8 kinds of foods, the recovery of AsA was over 91%, and that of ErA was over 88%. The RSD was 5.1% or less for both analytes. Analysis of 8 kinds of foods by both methods showed that this method gave better RSD values than the conventional method. AsA and ErA in all samples were confirmed by product ion scanning and selected reaction monitoring of LC-MS/MS.

Topics: Antioxidants; Ascorbic Acid; Chromatography, High Pressure Liquid; Chromatography, Liquid; Edetic Acid; Food Additives; Food Analysis; Liquid-Liquid Extraction; Phosphorous Acids; Sensitivity and Specificity; Solutions; Tandem Mass Spectrometry

To control the growth of Clostridium perfringens in cured meat products, the meat and poultry industries commonly follow stabilization parameters outlined in Appendix B, "Compliance Guidelines for Cooling Heat-Treated Meat and Poultry Products (Stabilization)" ( U.S. Department of Agriculture, Food Safety and Inspection Service [USDA-FSIS], 1999 ) to achieve cooling (54.4 to 4.4°C) within 15 h after cooking. In this study, extended cooling times and their impact on C. perfringens growth were examined. Phase 1 experiments consisted of cured ham with 200 mg/kg ingoing sodium nitrite and 547 mg/kg sodium erythorbate following five bilinear cooling profiles: a control (following Appendix B guidelines: stage A cooling [54.4 to 26.7°C] for 5 h, stage B cooling [26.7 to 4.4°C] for 10 h), extended stage A cooling for 7.5 or 10 h, and extended stage B cooling for 12.5 or 15 h. A positive growth control with 0 mg/kg nitrite added (uncured) was also included. No growth was observed in any treatment samples except the uncured control (4.31-log increase within 5 h; stage A). Phase 2 and 3 experiments were designed to investigate the effects of various nitrite and erythorbate concentrations and followed a 10-h stage A and 15-h stage B bilinear cooling profile. Phase 2 examined the effects of nitrite concentrations of 0, 50, 75, 100, 150, and 200 mg/kg at a constant concentration of erythorbate (547 mg/kg). Results revealed changes in C. perfringens populations for each treatment of 6.75, 3.59, 2.43, -0.38, -0.48, and -0.50 log CFU/g, respectively. Phase 3 examined the effects of various nitrite and erythorbate concentrations at 100 mg/kg nitrite with 0 mg/kg erythorbate, 100 with 250, 100 with 375, 100 with 547, 150 with 250, and 200 with 250, respectively. The changes in C. perfringens populations for each treatment were 4.99, 2.87, 2.50, 1.47, 0.89, and -0.60 log CFU/g, respectively. Variability in C. perfringens growth for the 100 mg/kg nitrite with 547 mg/kg erythorbate treatment was observed between phases 2 and 3 and may have been due to variations in treatment pH and NaCl concentrations. This study revealed the importance of nitrite and erythorbate for preventing growth of C. perfringens during a much longer (25 h) cooling period than currently specified in the USDA-FSIS Appendix B.

Topics: Ascorbic Acid; Clostridium perfringens; Colony Count, Microbial; Food Handling; Food Microbiology; Meat Products; Nitrites; Spores, Bacterial

The interfacial characteristics and antioxidant activities of erythorbyl laurate were investigated to provide information on practical applications as a multi-functional food additive. The critical micelle concentration (CMC) of erythorbyl laurate was 0.101mM and its foam stability was three times (half-life 24.33±0.94h) higher than that of Tween 20 (8.00±1.63h). In free radical scavenging assay, the negligible decrease in EC50 of erythorbyl laurate compared to erythorbic acid manifested that C-5 selective esterification of erythorbic acid with an acyl group (lauric acid) did not reduce the inherent antioxidant activity of the donor (erythorbic acid). Erythorbyl laurate formed lipid peroxides slower (i.e. retarded oxidation) in an emulsion system than did erythorbic acid. The localization of erythorbyl laurate as an emulsifier allowed the antioxidant molecules to be concentrated at the oil-water interface where oxidation is prevalent, which led to more effective retardation of lipid oxidation.

Topics: Antioxidants; Ascorbic Acid; Emulsifying Agents; Esterification; Food Additives; Half-Life; Laurates; Oxidation-Reduction

The synthesis of D-isoascorbyl stearate from D-isoascorbic acid and stearic acid with immobilized lipase (Novozym(®)435) as catalyst was studied. Response surface methodology and Box-Behnken design with six variables and three levels were employed to evaluate the effects of processing conditions on the conversion of D-isoascorbic acid. The results confirmed that the response surface method and statistical analysis were proved to be useful in developing optimal conditions for D-isoascorbyl stearate synthesis. The optimum conditions were predicted as follows: reaction temperature 48 °C, reaction time 17.7 h, immobilized lipase amount 50.0 % (w/w, of D-isoascorbic acid), substrate molar ratio 9:1 (stearic acid to D-isoascorbic acid), D-isoascorbic acid concentration 0.14 mol/L (based on solvent), 4A molecular sieve addition 200 g/L (based on solvent), and the optimal conversion was 90.6 %. Through the kinetics model fitting of the esterification, it was considered that the esterification conformed to a Ping-Pong bi-bi kinetic model with D-isoascorbic acid inhibition, and the obtained kinetic constants showed that the inhibition of D-isoascorbic acid and the enzyme affinity to substrate were abate with the increase of the reaction temperature.

Topics: Ascorbic Acid; Biocatalysis; Candida; Enzymes, Immobilized; Esterification; Fungal Proteins; Industrial Microbiology; Kinetics; Lipase; Solvents; Stearic Acids; Surface Properties; Temperature

Candida albicans D-erythroascorbate peroxidase (EAPX1), which can catalyze the oxidation of D-erythroascorbic acid (EASC) to water, was observed to be inducible in EAPX1-deficient and EAPX1-overexpressing cells via activity staining. EAPX1-deficient cells have remarkably increased intracellular reactive oxygen species and methylglyoxal independent of the intracellular EASC content. The increased methylglyoxal caused EAPX1-deficient cells to activate catalase-peroxidase and cytochrome c peroxidase, which led to defects in cell growth, viability, mitochondrial respiration, filamentation and virulence. These findings indicate that EAPX1 mediates cell differentiation and virulence by regulating intracellular methylglyoxal along with oxidative stresses, regardless of endogenous EASC biosynthesis or alternative oxidase expression.

Topics: Amino Acid Sequence; Animals; Ascorbate Peroxidases; Ascorbic Acid; Candida albicans; Cell Differentiation; Female; Glutathione; Mice; Mice, Inbred BALB C; Molecular Sequence Data; Oxygen Consumption; Pyruvaldehyde; Reactive Oxygen Species; Sequence Homology, Amino Acid; Virulence

Pork meat sausages were prepared using protein hydrolysates from mechanically deboned chicken meat (MDCM). In terms of the color, compared to the controls before and after storage, the redness (a*) was significantly higher in sausages containing MDCM hydrolysates, ascorbate, and sodium erythorbate. After storage, compared to the other sausage samples, the yellowness (b*) was lower in the sausages containing ascorbate and sodium erythorbate. TBARS was not significantly different among the sausage samples before storage, whereas TBARS and DPPH radical scavenging activities were significantly higher in the sausagescontainingascorbate and sodium erythorbate, compared to the other sausage samples after 4 wk of storage. In terms of sensory evaluation, the color was significantly higher in the sausages containing MDCM hydrolysates, ascorbate, and sodium erythorbate, compared to the other sausage samples after 4 wk of storage. The "off-flavor" and overall acceptability were significantly lower in the sausages containing MDCM hydrolysates than in the other sausage samples.. In most of the developed countries, meat from spent laying hens is not consumed, leading toan urgent need for effectively utilization or disposal methods. In this study, sausages were prepared using spent laying hens and protein hydrolysates from mechanically deboned chicken meat. Sausage can be made by spent laying hens hydrolysates, although overall acceptability was lower than those of other sausage samples.

Topics: Animals; Ascorbic Acid; Chickens; Color; Food Analysis; Food Handling; Food Storage; Humans; Hydrogen-Ion Concentration; Meat; Meat Products; Protein Hydrolysates; Swine; Taste; Thiobarbituric Acid Reactive Substances; Volatile Organic Compounds

Asymmetric total synthesis of (+)-gabosine C, (+)-pericosine B, and (+)-pericosine C has been reported from readily available d-(-)-isoascorbic acid and d-ribose involving Grubbs ring closing metathesis, Morita-Baylis-Hillman (MBH) reaction, and Luche reduction.

Topics: Ascorbic Acid; Carbasugars; Catalysis; Cyclohexanols; Cyclohexanones; Molecular Structure; Oxidation-Reduction; Ribose; Shikimic Acid; Stereoisomerism

The effects of L-ascorbic acid and its stable analogue L-ascorbic acid 2-glucoside on the restoration of liver mass and recovery of liver function after 70% partial hepatectomy (PH), were compared with other natural vitamin C analogues in rats in vivo. L-Ascorbic acid (100 mg/kg/d, intraperitoneally (i.p.))- and L-ascorbic acid 2-glucoside (50 mg/kg/d, i.p.)-treated rats showed an approximately 1.3-fold increase in the ratio of liver weight (LW) to body weight (BW), when compared to saline (as control)-, L-dehydroascorbic acid (150 mg/kg/d, i.p.)- and D-isoascorbic acid (150 mg/kg/d, i.p.)-administrated rats on day 3 after PH. Accordingly, 5-bromo-2-deoxyuridine-labeling index in the regenerating liver was significantly higher in L-ascorbic acid- and L-ascorbic acid 2-glucoside-treated rats compared with saline-, L-dehydroascorbic acid and D-isoascorbic acid-treated rats on day 1. In control rats, liver-related serum alanine aminotransferase (ALT) activity was rapidly elevated on day 1, and then decreased to near pre-operative levels on day 5 following PH. L-Ascorbic acid and L-ascorbic acid 2-glucoside significantly lowered the serum ALT on day 1 after PH compared with saline-, L-dehydroascorbic acid- and D-isoascorbic acid-administered rats. These results demonstrate that L-ascorbic acid and L-ascorbic acid 2-glucoside significantly promote the regeneration of liver mass and function with full recovery after liver injury.

Topics: Alanine Transaminase; Animals; Ascorbic Acid; Dehydroascorbic Acid; Hepatectomy; Liver Regeneration; Rats

An analysis of the components of the antioxidant defence system in exponential and stationary growth phases of filamentous fungus Phycomyces blakesleeanus and the response to the oxidative stress hydrogen peroxide were performed. There is a strong positive correlation between mycelial antioxidant capacity and the contents of gallic acid, d-erythroascorbate (d-EAA) or d-erythroascorbate monoglucoside (d-EAAG). These secondary metabolites are specifically synthesized by this fungus and reach maximal values in the stationary growth phase, suggesting that they can play some role in the antioxidant defence system of this fungus. There is a differential expression of the two more notable antioxidant activities, catalase (CAT) and superoxide dismutase (SOD), depending of the growth stage of P. blakesleeanus, CAT being expressed in the exponential and SOD in the stationary phase. Phycomyces blakesleeanus showed a high resistance to the oxidative stress caused by H2O2 (50 and 200 mM) which was higher in exponential phase. This higher resistance can be explained by the presence of CAT, glutathione peroxidase (GPx), and the probable contribution of glutathione-S-transferase (GST) and high levels of reduced form of glutathione (GSH). The transition to stationary phase was accompanied with a higher physiological oxidative damage illustrated by the higher protein carbonylation. In this growth stage the resistance of the fungus to the oxidative stress caused by H2O2 could be explained by the presence of SOD, GPx, and the probable contribution of GST as well as of secondary metabolites, mainly d-EAA and d-EAAG. These results highlight a specific response to oxidative stress by H2O2 depending on the growth phase of P. blakesleeanus.

Topics: Antioxidants; Ascorbic Acid; Catalase; Gallic Acid; Glucosides; Glutathione; Glutathione Peroxidase; Glutathione Transferase; Hydrogen Peroxide; Oxidants; Oxidative Stress; Phycomyces; Stress, Physiological; Superoxide Dismutase

The effect of nitrite and erythorbate on Clostridium perfringens spore germination and outgrowth in ham during abusive cooling (15 h) was evaluated. Ham was formulated with ground pork, NaNO2 (0, 50, 100, 150 or 200 ppm) and sodium erythorbate (0 or 547 ppm). Ten grams of meat (stored at 5 °C for 3 or 24 h after preparation) were transferred to a vacuum bag and inoculated with a three-strain C. perfringens spore cocktail to obtain an inoculum of ca. 2.5 log spores/g. The bags were vacuum-sealed, and the meat was heat treated (75 °C, 20 min) and cooled within 15 h from 54.4 to 7.2 °C. Residual nitrite was determined before and after heat treatment using ion chromatography with colorimetric detection. Cooling of ham (control) stored for 3 and 24 h, resulted in C. perfringens population increases of 1.46 and 4.20 log CFU/g, respectively. For samples that contained low NaNO2 concentrations and were stored for 3 h, C. perfringens populations of 5.22 and 2.83 log CFU/g were observed with or without sodium erythorbate, respectively. Residual nitrite was stable (p > 0.05) for both storage times. Meat processing ingredients (sodium nitrite and sodium erythorbate) and their concentrations, and storage time subsequent to preparation of meat (oxygen content) affect C. perfringens spore germination and outgrowth during abusive cooling of ham.

Topics: Animals; Ascorbic Acid; Clostridium perfringens; Colony Count, Microbial; Food Preservation; Food Preservatives; Meat Products; Sodium Nitrite; Spores, Bacterial; Swine; Temperature; Vacuum

The efficiency of different white wine antioxidant systems in preventing aldehyde production from amino acids by oxidative processes is not well understood. The aim of this study was to assess the efficiency of sulphur dioxide alone and in combination with either glutathione, ascorbic acid or its stereoisomer erythorbic acid, in preventing formation of the sensorially important compounds methional and phenylacetaldehyde from methionine and phenylalanine in model white wine. UHPLC, GC-MS/MS, LC-MS/MS, flow injection analysis and luminescence sensors determined both compositional changes during storage, and sulphur dioxide-aldehyde apparent equilibrium constants. Depending on temperature (25 or 45°C) or extent of oxygen supply, sulphur dioxide was equally or more efficient in impeding the production of methional compared to the other antioxidant systems. For phenylacetaldehyde, erythorbic acid or glutathione with sulphur dioxide provided improved inhibition compared to sulphur dioxide alone, in conditions of limited oxygen consumption. The results also demonstrate the extent to which sulphur dioxide addition can lower the free aldehyde concentrations to below their aroma thresholds.

Topics: Aldehydes; Amino Acids; Ascorbic Acid; Chromatography, High Pressure Liquid; Food Storage; Glutathione; Models, Biological; Oxidation-Reduction; Sulfur Dioxide; Tandem Mass Spectrometry; Wine

The microbial production of methylglyoxal in cheese has been linked to the formation of brown pigmentation and distinctive volatiles. This study investigated methods for preventing methylglyoxal-induced browning in Parmesan cheese through the addition of reducing agents. Cheeses were treated with the reducing agents sodium bisulfite, glutathione, and erythorbate at 2:1 and 4:1 molar ratios with added methylglyoxal, and then incubated at 10 °C. Colorimetric methods were used to determine degree of browning at 0, 3, and 6 d. Sodium bisulfite and glutathione inhibited the browning reactions of methylglyoxal compared with the control. Erythorbate was much less effective than the other compounds at inhibiting browning, yet was significantly less browned than the control. These reducing agents are thought to act as strong nucleophiles that can form thiohemiketals and thioketals at the carbonyl carbons of methylglyoxal.

Topics: Ascorbic Acid; Cheese; Colorimetry; Food Preservation; Glutathione; Maillard Reaction; Pyruvaldehyde; Reducing Agents; Sulfites

This study investigated the capacity of various antioxidants in reducing the formation of acrylamide during cookie processing. Five antioxidants, antioxidants of bamboo leaves (AOB), sodium erythorbate (SE), tea polyphenols (TP), vitamin E (VE), and tert-butyl hydroquinone (TBHQ), were individually added into cookie formulas, and acrylamide content was determined by liquid chromatography tandem mass spectrometry (LC-MS/MS). Cookie quality indexes, including flavor, brittleness, and water activity, were also evaluated. Results showed that the maximum inhibitory rate of acrylamide by AOB was achieved with addition of 0.2 g/kg AOB. Addition of AOB (0.2 g/kg), TP (0.1 g/kg), VE (0.1 g/kg), SE (0.1 g/kg), and TBHQ (0.2 g/kg) mitigated the formation of acrylamide by 63.9%, 43.0%, 71.2%, 49.6%, and 54.1%, respectively. Sensory evaluation showed that the color, texture, and flavor of cookies processed with either AOB (0.2 g/kg) or VE (0.1 g/kg) had no significant difference compared to control cookies (P > 0.05). The present study indicated that AOB (0.2 g/kg) and VE (0.1 g/kg) could not only effectively mitigate the formation of acrylamide, but also retain acceptable sensory attributes of cookies. This work shows the potential effectiveness of antioxidants in food processing to decrease acrylamide formation.. There is an urgent need for reducing the level of acrylamide produced during food processing. This study found that certain antioxidants (antioxidant of bamboo leaves and vitamin E) could effectively inhibit acrylamide formation in cookie processing without affecting sensory properties. The results suggested that the application of antioxidants could be an effective method to decrease acrylamide formation.

Topics: Acrylamide; Antioxidants; Ascorbic Acid; Bambusa; Chromatography, Liquid; Color; Female; Food Handling; Humans; Hydroquinones; Male; Plant Leaves; Polyphenols; Tandem Mass Spectrometry; Taste; Tea; Vitamin E

Burbank and Norkotah potato slices were dipped into 3% sodium acid sulfate (SAS), citric acid (CA), sodium erythorbate (SE), malic acid (MA), sodium acid pyrophosphate (SAPP), or a combination of SAS-CA-SE. Browning by polyphenol oxidase (PPO) obtained from potato extract with 0.04 to 0.016 g/mL of antibrowning solutions at pH 2.0 to 6.9 were measured by UV-Vis spectroscopy. The color of slices dipped in antibrowning solutions at pHs 2 to 7 and stored at 4 °C for 15 d was measured every 5 d by colorimeter. Headspace analysis of volatiles in raw and cooked potato samples was performed by selected ion flow tube mass spectrometer (SIFT-MS) and soft independent modelling by class analogy (SIMCA) analysis of the calculated odor activity values (OAV) determined interclass distances. Microbial growth was measured at 15 d. At unadjusted pHs (1.1 to 7.1), the PPO browning of the control and samples with SAPP was not significantly different, SAS, CA, and MA produced some inhibition and SE and SAS-CA-SE prevented browning. At pH 5 to 7, only SE and SAS-CA-SE were effective browning inhibitors. Based on the color of potato slices, SE was the most effective at pH 2 to 7, but SAS was most effective at unadjusted pH. Cooking increased volatile levels in the treated potatoes and decreased differences between volatile profiles. Differences between cooked samples may not be noticeable by the consumer because volatiles with high discriminating powers have low OAVs. SAS, CA, and SAS-CA-SE treatments inhibited microbial growth but SAPP, control, and SE did not, most likely due to pH.. Antibrowning agents inhibit polyphenol oxidase, increasing shelf life and consumer acceptability of processed raw potato products by preserving the color. Their effectiveness was shown to be mainly due to a pH effect, except SE, which was not pH dependent. MA, CA, and SAS-CA-SE are better acidulants for inhibition of color change as well as growth of spoilage bacteria, yeast, and mold than SAPP, the industry standard.

Topics: Ascorbic Acid; Catechol Oxidase; Citric Acid; Colony Count, Microbial; Color; Consumer Behavior; Diphosphates; Food Contamination; Food Handling; Food Microbiology; Food Preservation; Hydrogen-Ion Concentration; Maillard Reaction; Malates; Odorants; Solanum tuberosum; Sulfates; Volatile Organic Compounds

The properties of novel bolaamphiphiles that carry epimers of vitamin C (L-ascorbic acid and/or D-isoascorbic acid) as hydrophilic head groups, and an interconnecting aliphatic C(12) chain (DD, DL, and LL) were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) in the solid state (anhydrous powders) and in aqueous dispersions as a function of the surfactant concentration. Upon heating, the aqueous dispersions undergo a phase transition from a hydrated semicrystalline "coagel" to a micellar phase. The results suggest that the headgroup chirality determines the formation of either inter- or intramolecular hydrogen bonds between the polar heads, which affect the phase behavior and structural properties of the nanoassemblies produced by these surfactants in water dispersions. The DSC data of aqueous dispersions were analyzed to obtain the size distribution of the pores in the coagel state.

Topics: Ascorbic Acid; Furans; Hydrogen Bonding; Pyridones; Surface-Active Agents; Temperature; Thermodynamics

The stereochemical influence of antioxidant and flavanol compounds on oxidation processes in a model wine system was studied. The diastereoisomers, ascorbic acid and erythorbic acid, were used as antioxidants in a model wine system containing either (+)-catechin or (-)-epicatechin as the oxidizable flavanol compound. Samples were stored at 45 degrees C for a period of 14 days and analyzed by UV/visible spectrometry, CIELab, UPLC-PDA, and LC-MS. The results showed that less brown oxidative coloration occurred for samples with erythorbic acid for a given flavanol compound, while (+)-catechin provided less yellow coloration for a given antioxidant. Although erythorbic acid was degraded faster than ascorbic acid, it was associated with less decay in the accompanying flavanol compound. Xanthylium cation pigments were identified as the major contributor to color development. Furthermore, the production of pigment precursors, previously identified as furanone-substituted flavanols, was confirmed in all cases and their corresponding xanthylium cation pigments were lower in the presence of erythorbic acid than ascorbic acid. The results demonstrate that erythorbic acid is more efficient at minimizing oxidative color development than ascorbic acid in the model wine system.

Topics: Antioxidants; Ascorbic Acid; Catechin; Flavonols; Models, Chemical; Oxidation-Reduction; Stereoisomerism; Wine

A new hydrophilic interaction liquid chromatographic (HILIC) method for the simultaneous determination of isoascorbic (IAA) and ascorbic acid (AA) was developed. The separation of IAA and AA was studied in various HILIC stationary phases and the influence of the composition of the mobile phase, the ionic strength and the column temperature to the chromatographic characteristics is presented. The final method used an aminopropyl column under isocratic elution with acetonitrile-100 mM ammonium acetate solution (90:10, v/v) at a flow rate of 0.4 mL/min and a detection wavelength of 240 nm. This method was validated and the calibration curves were found to be linear in the range of 1.0-65 microg/mL for both IAA and AA. The method limit of detection for IAA determination in fish tissue was 2.3 microg/g. Inter-day precision (as %RSD(R)) was ranged between 0.56% and 8.3% at three concentration levels, whereas the respected recoveries ranged between 82% and 98%. This method was applied to the determination of IAA (as additive E315) in frozen redfish samples. The hyphenation of the HILIC separation with a tandem mass spectrometer was also studied and the problems encountered with negative electrospray ionization under HILIC separation conditions are discussed.

Topics: Animals; Antioxidants; Ascorbic Acid; Calibration; Chromatography, Liquid; Fishes; Limit of Detection; Reproducibility of Results; Tandem Mass Spectrometry

D-erythroascorbate (D-EAA), a five-carbon analogue of L-ascorbate (L-AA), and D-erythroascorbate monoglucoside (D-EAAG) are accumulated in Phycomyces blakesleeanus grown on glucose (99.5 and 1084 μg/g mycelial dry weight, respectively) and also excreted into the culture medium. Both compounds showed UV spectral properties and ionization constants similar to those of L-AA. D-EAAG was much more stable to aerobic oxidation than D-EAA and L-AA at acidic pH. D-EAAG is synthesized from D-erythroascorbate by a mycelial glucosyltransferase activity that uses UDP-glucose as glucose substrate donor with K(m) = 2.5 mM and 41.3 μM for D-EAA. This glucosyltransferase activity was maximal in the stationary growth phase in parallel with maximal production of D-EAAG. The presence of D-arabinose or D-arabinono-1,4-lactone in the culture medium produces the maximal accumulation of D-EAA and D-EAAG (about 30- and 4-fold with respect to that obtained in glucose culture). Both compounds showed greater antioxidant activity than L-AA and other standard antioxidants, with a capacity similar to that of L-AA to inhibit the growth of Escherichia coli.

Topics: Anti-Infective Agents; Antioxidants; Ascorbic Acid; Culture Media; Drug Stability; Glucosides; Glucosyltransferases; Phycomyces

L-(+)-Ascorbic acid and D-(-)-isoascorbic acid are epimers, with an opposite configuration at the C5 stereogenic chiral center. Single-chained surfactants that carry a L-ascorbic or d-isoascorbic acid residue as hydrophilic headgroup and an alkanoate tail as hydrophobic chain were synthesized. We refer to these as L-ASCn and D-ASCn, with n=8, 10, or 12. The role of the headgroup configuration in determining the nature of both the pure compounds and their nano assembly in aqueous dispersions were studied. Surface tension, infrared spectroscopy, differential scanning calorimetry, conductivity, small-angle X-ray scattering, and wide-angle X-ray diffractometry were used to characterize surfactant properties as a function of temperature and concentration. The L and D headgroup forms have significantly different hydration. This greatly affects the structure and stability of the aggregates in the micellar and coagel states.

Topics: Ascorbic Acid; Calorimetry, Differential Scanning; Entropy; Molecular Structure; Nanostructures; Spectrophotometry, Infrared; Stereoisomerism; Water; X-Ray Diffraction

We found that a strain of Penicillium sp. effectively converted L-ascorbic acid to a five-carbon analog, which was identified as L-erythroascorbic acid based on spectroscopic analysis. The conversion was achieved by growing culture or washed mycelia, with a yield of approximately 20-30% (mol/mol). The processes for the bioconversion and purification of the product are described.

Topics: Ascorbic Acid; Molecular Sequence Data; Penicillium; Soil Microbiology

We recently identified a microbial conversion of L-ascorbic acid (AsA) to L-erythroascorbic acid (eAsA), a five-carbon analog of AsA. In this paper, we show that ubiquitin plays a crucial role in this process. Based on an assay that determined AsA decomposition, we purified proteins that had N-terminal amino acid sequences identical to that of yeast ubiquitin. Purified ubiquitin facilitated decompositions of AsA and dehydro-AsA, accompanying a partial conversion to eAsA through C1-elimination. Acetylation or limited hydrolysis of ubiquitin abolished its activity. A mutant ubiquitin, with Lys6 replaced by Arg, completely lost activity, whereas a mutant, with six other Lys residues (positions at 11, 27, 29, 33, 48 and 63) substituted by Arg, retained activity. Thus, Lys6, which locates in close proximity to His68, is crucial for ubiquitin activity in the AsA conversion to eAsA.

Topics: Acetylation; Amino Acid Sequence; Animals; Ascorbic Acid; Cattle; Mutation; Penicillium; Ubiquitin

l-Ascorbic and d-isoascorbic acids have been used as the starting materials for the preparation of (3R,4'S)-3-(2',2'-dimethyl-1',3'-dioxolan-4'-yl)-1,4-dioxane-2,5-dione (IPTA), (3R and S, 4'S,6R)-3-methyl-6-(2',2'-dimethyl-1',3'-dioxolan-4'-yl)-1,4-dioxane-2,5-dione (IPTP) and (3R,4'R)-3-(2',2'-dimethyl-1',3'-dioxolan-4'-yl)-1,4-dioxane-2,5-dione (IPEA), three novel 1,4-dioxane-2,5-dione-type monomers. Ring-opening homopolymerisation and copolymerisation of the IPTA monomer, derived from l-ascorbic acid, with d,l-lactide have been performed. The polymers were characterised by elemental microanalysis, as well as IR and (1)H and (13)C NMR spectroscopies. GPC was used to estimate product molecular weights, and thermal studies (DSC and TGA) revealed that all the polymers were amorphous, being stable up to 250 degrees C under nitrogen.

Topics: Ascorbic Acid; Dioxanes; Molecular Structure; Polymers

Since the double Deltagrx1Deltagrx2 mutant is hypersensitive to selenite we decided to evaluate mechanisms underlying this phenomenon and establish the roles of other components of yeast glutaredoxin system, in particular glutaredoxin 5 in the selenite resistance. We found elevation in the intracellular and mitochondrial superoxide production in the Deltagrx1Deltagrx2 and Deltagrx5 mutants after Se(IV) treatment. The last effect was more pronounced for cells lacking the mitochondrial Grx5 protein. We also recorded selenite-induced increase in the peroxide production in all strains tested. Nonfermentable carbon sources, glycerol and ethanol, augmented selenite toxicity. Hypo- and anoxia protected against the harmful effects of Se(VI). Augmentation of the intracellular levels of two endogenous antioxidants, erythroascorbic acid and glutathione confers resistance to selenite. We recorded a strain-unspecific, selenite-mediated decrease in the level of acid-soluble thiols. Collectively, our data demonstrate that hypersensitivity to the Deltagrx1Deltagrx2 and Deltagrx5 disruptants to selenite is mediated by altered intracellular redox equilibrium.

Topics: Ascorbic Acid; Ethanol; Glutaredoxins; Glutathione; Glycerol; Mutation; Oxidative Stress; Oxygen; Peroxides; Reactive Oxygen Species; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Sodium Selenite; Sulfhydryl Compounds

Humans use two sodium-ascorbate cotransporters (hSVCT1 and hSVCT2) for transporting the dietary essential micronutrient ascorbic acid, the reduced and active form of vitamin C. Although the human liver plays a pivotal role in regulating and maintaining vitamin C homeostasis, vitamin C transport physiology and regulation of the hSVCT systems in this organ have not been well defined. Thus, this research used a human hepatic cell line (HepG2), confirming certain results with primary human hepatocytes and determined the initial rate of ascorbic acid uptake to be Na(+) gradient, pH dependent, and saturable as a function of concentration over low and high micromolar ranges. Additionally, hSVCT2 protein and mRNA are expressed at higher levels in HepG2 cells and native human liver, and the cloned hSVCT2 promoter has more activity in HepG2 cells. Results using short interfering RNA suggest that in HepG2 cells, decreasing hSVCT2 message levels reduces the overall ascorbic acid uptake process more than decreasing hSVCT1 message levels. Activation of PKC intracellular regulatory pathways caused a downregulation in ascorbic acid uptake not mediated by a single predicted PKC-specific amino acid phosphorylation site in hSVCT1 or hSVCT2. However, PKC activation causes internalization of hSVCT1 but not hSVCT2. Examination of other intracellular regulatory pathways on ascorbic acid uptake determined that regulation also potentially occurs by PKA, PTK, and Ca(2+)/calmodulin, but not by nitric oxide-dependent pathways. These studies are the first to determine the overall ascorbic acid uptake process and relative expression, regulation, and contribution of the hSVCT systems in human liver epithelial cells.

Topics: Ascorbic Acid; Budesonide; Cell Line, Tumor; Dehydroascorbic Acid; Dexamethasone; Epithelial Cells; Gene Expression Regulation; Hepatocytes; Humans; Liver; Mifepristone; Organic Anion Transporters, Sodium-Dependent; Promoter Regions, Genetic; Protein Kinase C; RNA, Small Interfering; Sodium-Coupled Vitamin C Transporters; Symporters; Tetradecanoylphorbol Acetate; Transfection

Higher plants, protists and fungi possess cyanide-resistant respiratory pathway, which is mediated by alternative oxidase (AOX). The activity of AOX has been found to be dependent on several regulatory mechanisms including gene expression and posttranslational regulation. In the present study, we report that the presence of cyanide in culture medium remarkably retarded the growth of alo1/alo1 mutant of Candida albicans, which lacks d-arabinono-1,4-lactone oxidase (ALO) that catalyzes the final step of d-erythroascorbic acid (EASC) biosynthesis. Measurement of respiratory activity and Western blot analysis revealed that increase in the intracellular EASC level induces the expression of AOX in C. albicans. AOX could still be induced by antimycin A, a respiratory inhibitor, in the absence of EASC, suggesting that several factors may act in parallel pathways to induce the expression of AOX. Taken together, our results suggest that EASC plays important roles in activation of cyanide-resistant respiration in C. albicans.

Topics: Ascorbic Acid; Candida albicans; Cyanides; Drug Resistance, Fungal; Mitochondrial Proteins; Oxidoreductases; Oxygen; Plant Proteins

Mammalian dimeric dihydrodiol dehydrogenase (DD) is identical to NADP+-dependent D-xylose dehydrogenase. A recent investigation showed that the three-dimensional structure of monkey DD is similar to those of prokaryotic NADP(H)-dependent glucose-fructose oxidoreductase (GFO) and 1,5-anhydro-D-fructose reductase (AFR); however, it differs in coenzyme-binding and catalytic residues. Dimeric DD has a high affinity for NADP(H) when compared with AFR and differs from both GFO and AFR in its specificity for sugars and hydrophobic xenobiotic compounds as substrates. The crystal structure of monkey dimeric DD complexed with the inhibitor isoascorbic acid has been determined at 2.59 angstroms resolution. Molecular modelling of coenzyme binding complemented with site-directed mutagenesis has been utilized to propose a binding mode for the coenzyme molecule and to gain insights into the roles of the residues comprising the active site and coenzyme-binding domain of DD. Several key residues have been identified within the coenzyme-binding domain, including Arg37, Arg41, His76 and His79, that contribute to the high affinity for coenzyme. The interaction of Arg37 and Arg41 with the 2'-phosphate and adenine-ring moiety of the coenzyme has been established from the large increases (29-fold to 438-fold) in the Kd values for NADP(H) for the R37D and R41D mutant enzymes. The mutation of several residues lining the inhibitor-binding site of DD suggested the involvement of Trp125, Phe154, Trp254 and Phe279 in determining the broad substrate specificity and inhibitor potency of the enzyme. In addition, mutants of Lys97, which is present near the catalytic residue Tyr180, greatly reduced the kcat value without changing the Kd values for coenzyme, suggesting the importance of Lys97 in the catalytic mechanism of DD.

Topics: Amino Acid Sequence; Animals; Ascorbic Acid; Binding Sites; Catalysis; Crystallography, X-Ray; Dimerization; Hydrogen Bonding; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Oxidoreductases; Protein Binding; Protein Structure, Secondary; Protein Structure, Tertiary; Sequence Homology, Amino Acid

A new hydrophilic interaction liquid chromatography method for the simultaneous determination of ascorbic acid (AA), erythorbic acid (EA), 2-O-alpha-D-glucopyranosyl-L-ascorbic acid (AA-2G) and 2-O-beta-D-glucopyranosyl-L-ascorbic acid (AA-2betaG) was developed using a diol column with an isocratic solution of acetonitrile-66.7 mM ammonium acetate solution (85:15, v/v) at a detection wavelength of 260 nm. The calibration curves were found to be linear in the range of 1-50 microg/ml for AA and EA and in the range of 2.5-100 microg/ml for AA-2G and AA-2betaG. Detection limits of AA, EA, AA-2G and AA-2betaG were 0.3, 0.3, 0.03 and 0.03 microg/ml, respectively. This method was satisfactorily applied to the determination of AA, EA, AA-2G and AA-2betaG in a fruit, a food and beverages. The results show that the procedure is simple and sensitive and that it can be employed for the simultaneous determination of AA and its related compounds in foods and beverages.

Topics: Ascorbic Acid; Beverages; Chromatography, Liquid; Food Analysis; Molecular Structure; Reproducibility of Results

To investigate the mechanism of L-ascorbic acid uptake by rabbit corneal epithelial cells and to functionally characterize the specific transporter involved in this translocation process.. Uptake studies were carried out with SIRC (Statens Seruminstitut Rabbit Cornea) and rPCEC (rabbit Primary corneal epithelial cell culture) in 12-well plates using [14C] Ascorbic acid (AA). Uptake was done in the presence of L-ascorbic acid and D-isoascorbic acid to delineate stereospecificity. Inhibition studies were performed in the presence of D-glucose a substrate for GLUT and also para amino hippuric acid (PAHA) a substrate for organic anion transporter. Effects of pH and sodium on the uptake of AA were characterized. Concentration dependency studies were performed. Energy dependence of AA uptake was investigated with ouabain and sodium azide in rPCEC. Reverse Transcription-polymerase chain reaction (RT-PCR) was also performed.. Uptake of AA was inhibited by about 90% and 50% respectively in the presence of L-ascorbic acid and D-isoascorbic acid in both SIRC and rPCEC. Uptake was unaltered by D-glucose and PAHA. The process was sodium dependent and saturable at higher concentrations. Ouabain and sodium azide significantly diminished the uptake process. It also decreased with a reduction in pH. The RT-PCR results showed the presence of SVCT2 but not SVCT1.. Uptake of AA across rabbit corneal epithelial cells appears to be a carrier mediated active process. A saturable, sodium dependent, and pH sensitive transporter with high specificity for L-ascorbic acid was functionally characterized and was identified as SVCT2.

Topics: Animals; Ascorbic Acid; Biological Transport; Cell Line; Dose-Response Relationship, Drug; Epithelium, Corneal; Fibroblasts; Glucose; Hydrogen-Ion Concentration; Organic Anion Transporters, Sodium-Dependent; Ouabain; p-Aminohippuric Acid; Rabbits; Reverse Transcriptase Polymerase Chain Reaction; Sodium Azide; Sodium-Coupled Vitamin C Transporters; Symporters

Erythroascorbic acid (eAsA) is a five-carbon analog of ascorbic acid, and it is synthesized from D-arabinose by D-arabinose dehydrogenase (ARA) and D-arabinono-gamma-lactone oxidase. We found an NAD+-specific ARA activity which is operative under submillimolar level of d-arabinose in the extracts of Saccharomyces cerevisiae. The hypothetical protein encoded by YMR041c showed a significant homology to a l-galactose dehydrogenase which plays in plant ascorbic acid biosynthesis, and we named it as Ara2p. Recombinant Ara2p showed NAD+-specific ARA activity with Km=0.78 mM to d-arabinose, which is 200-fold lower than that for the conventional NADP+-specific ARA, Ara1p. Gene disruptant of ARA2 lost entire NAD+-specific ARA activity and the conspicuous increase in intracellular eAsA by exogenous d-arabinose feeding, while the double knockout mutant of ARA1 and ARA2 still retained measurable amount of eAsA. It demonstrates that Ara2p, not Ara1p, mainly contributes to the production of eAsA from d-arabinose in S. cerevisiae.

Topics: Arabinose; Ascorbic Acid; Gene Deletion; Recombinant Proteins; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Sugar Alcohol Dehydrogenases

D-Erythroascorbate and D-erythroascorbate glucoside have been identified in the Zygomycete fungus Phycomyces blakesleeanus. Ascomycete and Basidiomycete fungi also synthesise D-erythroascorbate instead of l-ascorbate, suggesting that D-erythroascorbate synthesis evolved in the common ancestor of the fungi. Both compounds accumulate in P. blakesleeanus at higher levels than observed in other fungal species. D-Erythroascorbate glucoside reduced dichlorophenolindophenol as effectively as L-ascorbate, but was more stable to autoxidation. D-Erythroascorbate glucoside predominated in spores and stationary phase mycelium. Free D-erythroascorbate accumulated during the exponential phase of mycelial growth and decreased to very low levels in the stationary phase. This suggests an association between growth and free D-erythroascorbate. P. blakesleeanus converted exogenous D-arabinose to D-erythroascorbate and its glucoside. A monomeric NAD-dependent D-arabinose dehydrogenase of 41 kDa was purified to near homogeneity. The enzyme oxidised D-arabinose, L-galactose, and L-fucose. Correspondingly, mycelium converted exogenous L-galactose and L-fucose to L-ascorbate and 6-deoxyascorbate, respectively. The antioxidant role of D-erythroascorbate and its glucoside is discussed.

Topics: 2,6-Dichloroindophenol; Arabinose; Ascorbic Acid; Fucose; Galactose; Glycosylation; Molecular Weight; Mycelium; Oxidation-Reduction; Phycomyces; Spores; Sugar Alcohol Dehydrogenases

It has previously been found that a process based on solubilization at pH 2.7 gives high yields of herring muscle proteins with good functionality. In this study, the development of lipid oxidation during acid processing of herring mince was studied. It was tested how modifications of the process conditions and/or additions of antioxidants could prevent lipid oxidation during the actual process and then during ice storage of the protein isolates. Processing parameters evaluated were prewash of the mince, exposure time to pH 2.7, inclusion or exclusion of a high-speed centrifugation, and addition of antioxidants. Antioxidants tested were erythorbate (0.2%, 9.3 mM), sodium tripolyphosphate (STPP; 0.2%, 5.4 mM), ethylenediaminetetraacetic acid (EDTA; 0.044%, 1.5 mM), and milk proteins (4%). The first three antioxidants were added in the prewash or during the homogenization step, whereas milk proteins were added to the final precipitate. At time 0, all isolates were analyzed for pH, moisture content, and thiobarbituric reactive substances (TBARS). Selected isolates were also analyzed for lipid and protein content. Stability during ice storage was followed in terms of odor, TBARS, and color (a/b values). Extensive lipid oxidation took place using the "control" process without high-speed centrifugation. This was not significantly (p < or = 0.05) affected by a prewash or varied exposure time to pH 2.7. Including high-speed centrifugation (20 min, 10,000g) significantly (p < or = 0.05) reduced TBARS values, total lipids, a values and b values. Erythorbate alone, or in combination with STPP/EDTA, significantly (p < or = 0.05) reduced lipid oxidation during processing if added in the prewash or homogenization step. During ice storage, better stability was gained when antioxidants were added in both of these steps and when EDTA was used instead of STPP.

Topics: Antioxidants; Ascorbic Acid; Edetic Acid; Fish Products; Fish Proteins; Food Handling; Hydrogen-Ion Concentration; Lipid Peroxidation; Milk Proteins; Odorants; Polyphosphates; Solubility; Thiobarbituric Acid Reactive Substances

[structures: see text] A versatile (S)-3-(hydroxymethyl)butane-1,2,4-triol building block has been synthesized starting from D-isoascorbic acid, a common food preservative. The key transformation in this approach was the introduction of branching through a high yield and fully regioselective epoxide opening. This flexible synthon has been elaborated to a new class of (dihydro-)N-homo(phyto)ceramides.

Topics: Ascorbic Acid; Butanols; Catalysis; Ceramides; Food Preservatives; Indicators and Reagents; Molecular Structure; Stereoisomerism

A D-erythorbic acid-forming soluble flavoprotein, gluconolactone oxidase (GLO), was purified from Penicillium cyaneo-fulvum strain ATCC 10431 and partially sequenced. Peptide sequences were used to isolate a cDNA clone encoding the enzyme. The cloned gene exhibits high levels of similarity with the genes encoding other known eukaryotic lactone oxidases and also with the genes encoding some putative prokaryotic lactone oxidases. Analysis of the coding sequence of the GLO gene indicated the presence of a typical secretion signal sequence at the N terminus of GLO. No other targeting or anchoring signals were found, suggesting that GLO is the first known lactone oxidase that is secreted rather than targeted to the membranes of the endoplasmic reticulum or mitochondria. Experimental evidence, including the N-terminal sequence of mature GLO and data on glycosylation and localization of the enzyme in native and recombinant hosts, supports this analysis. The GLO gene was expressed in Pichia pastoris, and recombinant GLO was produced by using the strong methanol-induced AOX1 promoter. In order to evaluate the suitability of purified GLO for production of D-erythorbic acid, we immobilized it on N-hydroxysuccinimide-activated Sepharose and found that the immobilized GLO retained full activity during immobilization but was rather unstable under reaction conditions. Our results show that both soluble and immobilized forms of GLO can, in principle, be used for production of D-erythorbic acid from D-glucono-delta-lactone or (in combination with glucose oxidase and catalase) from glucose. We also demonstrated the feasibility of glucose-D-erythorbic acid fermentation with recombinant strains coexpressing GLO and glucose oxidase genes, and we analyzed problems associated with construction of efficient D-erythorbic acid-producing hosts.

Topics: Alcohol Oxidoreductases; Ascorbic Acid; Cloning, Molecular; Molecular Sequence Data; Penicillium; Pichia; Recombinant Proteins; Stereoisomerism

One-year-old seedlings from an ozone-sensitive half-sib family of loblolly pine (Pinus taeda L.) were transplanted into replicated plots in blocks in a large forest clearing near Nacogdoches, Texas. Seedlings were either non-treated (controls) or treated bi-weekly with foliar sprays of ethylenediurea (EDU), at 150, 300 or 450 ppm or sodium erythorbate (NaE), at 515, 1030, or 1545 ppm, for three growing seasons. Results from the final third year harvest indicated that both EDU and NaE increased all growth parameters, with significant differences only for EDU at 450 ppm. Both EDU and NaE would be useful for long-term studies on assessing the effects of ambient ozone on established native plants.

Topics: Air Pollutants; Antioxidants; Ascorbic Acid; Environmental Monitoring; Ozone; Phenylurea Compounds; Pinus; Pinus taeda

In some lower eukaryotes, D-erythroascorbic acid, a five-carbon analog of L-ascorbic acid, is present instead of L-ascorbic acid. We have cloned ALO1, the gene encoding D-arabinono-1,4-lactone oxidase, which catalyzes the final step of D-erythroascorbic acid biosynthesis in Candida albicans. The ALO1 gene contained a continuous open reading frame of 1,671 bp that encodes a polypeptide consisting of 557 amino acids with a calculated molecular mass of 63,428 Da. To investigate the functional roles of D-erythroascorbic acid in C. albicans, we disrupted or overexpressed the ALO1 gene. In the alo1/alo1 null mutants, the activity of D-arabinono-1,4-lactone oxidase was completely lost and D-erythroascorbic acid could not be detected. When ALO1 on a multicopy plasmid was transformed in C. albicans, the enzyme activity and the intracellular D-erythroascorbic acid level were increased up to 3.4-fold and 4.0-fold, respectively. The alo1/alo1 null mutants of C. albicans showed increased sensitivity towards oxidative stress. Overexpression of ALO1 made the cells more resistant to the same stress. The alo1/alo1 mutants showed defective hyphal growth and attenuated virulence. Taken together, our results suggest that D-erythroascorbic acid functions as an important antioxidant and can be considered one of the virulence factors enhancing the pathogenicity of C. albicans.

Topics: Amino Acid Sequence; Animals; Ascorbic Acid; Candida albicans; Candidiasis; Cloning, Molecular; Female; Gene Deletion; Mice; Mice, Inbred BALB C; Molecular Sequence Data; Oxidative Stress; Sequence Analysis, DNA; Sugar Alcohol Dehydrogenases; Virulence

A standard curve for the quantification of L-ascorbic acid (L-AA) by capillary zone electrophoresis (CZE) was established, and the quantification of ascorbic acid and total ascorbic acid in fruits (lemon, Sunkist, and pineapple) and spinach were performed using D-isoascorbic acid (D-IAA) as an internal standard. The minimum detection limits (MDLs) for L-AA and D-IAA were determined to be 1 and 2 microg/mL, respectively, at 265 nm. Dehydroascorbic acid (DHAA) in fruits and spinach was quantified in the presence of DL-homocysteine. The recoveries for L-AA in these juices were between 95 and 105%.

Topics: Ascorbic Acid; Citrus; Electrophoresis, Capillary; Fruit; Spinacia oleracea

The relevance of NADH-cytochrome b(5) reductase to the NADH-dependent reduction of D-erythroascorbyl free radical was investigated in Saccharomyces cerevisiae. MCR1, which is known to encode NADH-cytochrome b(5) reductase in S. cerevisiae, was disrupted by the insertion of URA3 gene into the gene of MCR1. In the mcr1 disruptant cells, the activity of NADH-D-erythroascorbyl free radical reductase almost disappeared and the intracellular level of D-erythroascorbic acid was about 11% of that of the congenic wild-type strain. In the transformant cells carrying MCR1 in multicopy plasmid, the intracellular level of D-erythroascorbic acid and the activity of NADH-D-erythroascorbyl free radical reductase increased up to 1.7-fold and 2.1-fold, respectively. Therefore, it indicated that the MCR1 product, mitochondrial NADH-cytochrome b(5) reductase, plays a key role in the NADH-dependent reduction of D-erythroascorbyl free radical in S. cerevisiae. On the other hand, the mcr1 disruptant cells were hypersensitive to hydrogen peroxide and menadione, and overexpression of MCR1 made the cells more resistant against oxidative stress. These results suggested that the mitochondrial NADH-cytochrome b(5) reductase functions as NADH-D-erythroascorbyl free radical reductase and plays an important role in the response to oxidative damage in S. cerevisiae.

Topics: Ascorbic Acid; Cytochrome Reductases; Cytochrome-B(5) Reductase; Free Radicals; Mitochondria; Oxidation-Reduction; Oxidative Stress; Saccharomyces cerevisiae

Topics: Adenosine; Adenosylhomocysteinase; Ascorbic Acid; Cyclopentanes; Hydrolases; Nucleosides

A reduction of dehydroerythorbic acid (DERA) to erythorbic acid (ERA) in vitamin C-deficient guinea pigs was evaluated and compared with that of dehydroascorbic acid (DASA). Thirty-six guinea pigs were fed with vitamin C-deficient diets for 18 days. On day 19, the guinea pigs were divided into four groups for the administration of 100 mg of DERA, ERA, ascorbic acid (ASA), or DASA every day. After 12 days of oral administration, the concentration of DERA, ERA, ASA, and DASA in the liver, adrenal, spleen, kidney, and plasma of guinea pigs was determined by HPLC. A recovery from scurvy was measured in terms of weight gain and serum alkaline phosphatase activity. All four groups showed similar recovery, indicating that the oral administration of relatively high concentrations of DERA reversed the effects of scurvy in vitamin C-deficient guinea pigs. In spite of DERA or DASA administration, ERA or ASA was mainly detected in the tissues. The reduction ratios of DEAR and DASA were similar (approximately 80%) in all tissues except spleen. These results suggest that both DASA and DERA are taken up and reduced to ASA or ERA in vivo.

Topics: Animals; Antioxidants; Ascorbic Acid; Ascorbic Acid Deficiency; Dehydroascorbic Acid; Guinea Pigs; Male; Scurvy

Capillary zone electrophoresis (CZE) was used for separation of L-ascorbic acid (L-AA) and D-isoascorbic acid (D-IAA) in a model system. The effects of borate buffer concentration (0.05-0.25 M) and pH (pH 7.5-9.0) on migration time, resolution (Rs), and theoretical plates (N) were investigated. The migration times of L-AA and D-IAA increased with the increasing pH of carrier electrolyte (0.2 borate buffer), and the resolutions (Rs) of L-AA and D-IAA were calculated to be 12.98 at pH 9.0. Concentrations of borate buffer (pH 9.0) increased the Rs values of L-AA and D-IAA, and buffer concentrations >0.1 M were found to be effective for separation of L-AA and D-IAA. Methanol in the carrier electrolyte was also influential in improving the separation of L-AA and D-IAA, which increased with the increasing concentrations (0-10%) of methanol. The optimal separation conditions for L-AA and D-IAA were as follows: carrier electrolyte, 0.2 M borate buffer (pH 9.0); applied voltage, 25 kV, with an uncoated fused silica capillary, 75 microm (i.d.) x 57 cm.

Topics: Ascorbic Acid; Electrophoresis, Capillary; Hydrogen-Ion Concentration

A convenient synthesis of (S)- and (R)-4-vinyl oxazolidin-2-one 1 and 2 from the same inexpensive starting material, D-isoascorbic acid, is described. The title compounds were obtained in 44% and 38% yield, respectively, by operationally simple steps. This approach is a suitable alternative to the literature methods and enhances the synthetic utility of these intermediates. Inc.

Topics: Ascorbic Acid; Oxazoles; Stereoisomerism

One of the possible pathways of the formation of mutagens in heated foods is through the pyrazine cation radical generated in the early stage of the Maillard reaction. The aim of the present study was to elucidate how food reductones contribute to the pyrazine cation radical generation in the reaction of glucose (Glc) and glycine (Gly), and to the formation of the mutagens in the reaction of Glc, Gly and creatinine. Electron spin resonance (ESR) studies showed that fragrant reductones, 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF) and 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone (HEMF), generated in the Maillard reactions, enhanced the generation of the pyrazine cation radical in the reaction of Glc and Gly, and the reaction of DMHF or HEMF with Gly generated a larger amount of the pyrazine cation radical than the reaction of Glc and Gly, indicating that the furanones were intermediates of the pyrazine cation radical. By contrast, food antioxidants, ascorbic acid and erythorbic acid, effectively scavenged the pyrazine cation radical generated in the reaction of Glc and Gly. DMHF and HEMF were not effective to modulate the mutagen formation in the reaction of Glc, Gly and creatinine, and the mutagenicity produced in the reaction of DMHF or HEMF, Gly and creatinine was lower than that produced in the reaction of Glc, Gly and creatinine. On the other hand, ascorbic acid and erythorbic acid were effective to decrease the mutagen formation in the reaction of Glc, Gly and creatinine.

Topics: Animals; Antioxidants; Ascorbic Acid; Cations; Creatinine; Electron Spin Resonance Spectroscopy; Food Analysis; Food Contamination; Free Radicals; Glucose; Glycine; In Vitro Techniques; Maillard Reaction; Microsomes, Liver; Mutagenicity Tests; Mutagens; Pyrazines; Rats; Salmonella typhimurium

Saccharomyces cerevisiae cells incubated with D-glucose (D-Glc), D-galactose or D-mannose (D-Man) synthesised D-erythroascorbic acid (D-EAA) but not L-ascorbic acid (L-AA). Accumulation of D-EAA was observed in cells incubated with D-arabinose (D-Ara) whilst accumulation of L-AA occurred in cells incubated with L-galactose (L-Gal), L-galactono-1,4-lactone and L-gulono-1,4-lactone. When S. cerevisiae cells were incubated with D-[U-(14)C]Glc, D-[U-(14)C]Man or L-[1-(14)C]Gal, incorporation of radioactivity into L-AA was observed only with L-[1-(14)C]Gal. Pre-incubation of yeast cells with D-Ara substantially reduced the incorporation of L-[1-(14)C]Gal into L-AA. Our results indicate that, under appropriate conditions, yeast cells can synthesise L-AA via the pathway naturally used for D-EAA biosynthesis.

Topics: Ascorbic Acid; Carbon Radioisotopes; Cell-Free System; Galactose; Galactose Dehydrogenases; Glucose; Mannose; Plants; Saccharomyces cerevisiae; Sugar Alcohol Dehydrogenases

L-Ascorbic acid (AA) plays an important role in biological systems as an electron donor. Erythorbic acid (EA) is the epimer of AA and has chemical characteristics very similar to those of AA. It is demonstrated in the present study by 1H-NMR that dehydro-L-ascorbic acid (DAA) was reduced by EA under neutral conditions but not acidic, and that dehydroerythorbic acid (DEA) was also reduced by AA under the same conditions. These reactions also occurred at a low concentration close to the concentration of AA in such biological tissue as the liver. Furthermore, the interconversion of DAA and AA at neutral pH and low concentration was also confirmed by radioluminography. These results suggest the interconversion between DAA and AA in vivo.

Topics: Ascorbic Acid; Buffers; Dehydroascorbic Acid; Deuterium Oxide; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Oxidation-Reduction

Determination of dehydroascorbic acid in biological samples most commonly involves indirect measurement. The concentration is calculated by subtraction of the measured ascorbic acid concentration from that of total ascorbic acid analyzed after reduction of the dehydroascorbic acid present; a methodology also referred to as subtraction methods. Consequently, successful determination of dehydroascorbic acid is dependent on proper sample handling, quantitative reduction of the compound, and accurate quantification of both ascorbic acid and total ascorbic acid. In this paper, the recently introduced reductant tris[2-carboxyethyl]phosphine (TCEP) is evaluated as a reliable alternative to the commonly used reducing agent dithiothreitol (DTT). The results show that TCEP offers a more efficient reduction of dehydroascorbic acid at low pH compared to that of DTT. Moreover, while DTT maintains a reducing sample environment for less than 24 h, TCEP show complete protection from oxidation of ascorbic acid for at least 96 h following sample preparation. Removal of TCEP prior to analysis is unnecessary. A revised HPLC-EC method incorporating TCEP as reductant as well as the coanalysis of isoascorbic acid and uric acid is presented. The within- and between-day coefficients of variation for the complete assay are less than 1.5 and 3.5% for all analytes. As a whole, the method presented here is simpler and more reliable than existing methods.

Topics: Ascorbic Acid; Chromatography, High Pressure Liquid; Dehydroascorbic Acid; Dithiothreitol; Humans; Hydrogen-Ion Concentration; Models, Chemical; Oxygen; Phosphines; Reproducibility of Results; Time Factors; Uric Acid

The concentrations of erythorbic acid(ErA) and L-ascorbic acid(AsA) in the tissues of guinea pigs orally administered AsA or ErA were measured over the passage of time using high-performance liquid chromatography. Guinea pigs were each administered 5 mg AsA or 100 mg ErA, and killed at a specified time thereafter. The AsA concentrations in the tissues of AsA-administered guinea pigs and the ErA concentrations in the tissues of ErA-administered guinea pigs increased for 3 h after the respective administrations and decreased thereafter in both groups. The AsA concentration in the tissues of AsA-administered guinea pigs tended to be similar to the sum of AsA and ErA concentrations in the ErA-administered guinea pigs within 3 h after administration.

Topics: Adrenal Glands; Animals; Ascorbic Acid; Chromatography, High Pressure Liquid; Guinea Pigs; Kidney; Liver; Spleen; Time Factors

The formation of aniline from sodium salt of 6-hydroxy-5-(phenylazo)-2-naphthalenesulphonic acid (SS-AN, C.I. 15970, Orange RN), a subsidiary colour in the Japanese colour additive Food Yellow No. 5 (Y-5, C.I. 15985, Sunset Yellow FCF), was investigated in the artificial gastric fluid (AGF) and in the artificial intestinal fluid (AIF) as prescribed in the degradation test in the Japanese Pharmacopoeia (1996). Aniline concentrations of 0.3-6.8 micrograms/ml were found in 0.1% SS-AN solutions with 0.1-5.0% ascorbic acid or erythorbic acid after 24 h at 37 degrees C. This simulates a mixture of dye and ascorbic acid that might be ingested. The amount of aniline generated depended upon the temperature in these systems. In systems to which sucrose had been added, an increase in the amount of aniline generated was observed. However, no aniline generation was observed in the 0.1% SS-AN solutions in the AGF or AIF at 37 degrees C for 24 h. Furthermore, the generation of aniline was not seen in AGF and AIF at higher temperatures in the range of 37-80 degrees C. It was not generated by the degradation of SS-AN in the presence of digestive enzymes.

Topics: Aniline Compounds; Ascorbic Acid; Azo Compounds; Chromatography, High Pressure Liquid; Food Coloring Agents; Temperature

The three recent EU directives which fixed maximum permitted levels (MPL) for food additives for all member states also include the general obligation to establish national systems for monitoring the intake of these substances in order to evaluate their use safety. In this work, we considered additives with primary antioxidant technological function for which an acceptable daily intake (ADI) was established by the Scientific Committee for Food (SCF): gallates, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and erythorbic acid. The potential intake of these additives in Italy was estimated by means of a hierarchical approach using, step by step, more refined methods. The likelihood of the current ADI to be exceeded was very low for erythorbic acid, BHA and gallates. On the other hand, the theoretical maximum daily intake (TMDI) of BHT was above the current ADI. The three food categories found to be main potential sources of BHT were "pastry, cake and biscuits", "chewing gums" and "vegetables oils and margarine"; they overall contributed 74% of the TMDI. Actual use of BHT in these food categories is discussed, together with other aspects such as losses of this substance in the technological process and percentage of ingestion in the case of chewing gums.

Topics: Adolescent; Antioxidants; Ascorbic Acid; Butylated Hydroxyanisole; Butylated Hydroxytoluene; European Union; Female; Food Preservatives; Gallic Acid; Humans; Italy; Legislation, Food; Nutrition Policy

Introduction of phenolic antioxidants, thiol compounds and reductones into the heated model system composed of glucose/glycine/creatinine was effective to scavenge the intermediary pyrazine cation radical and to reduce the mutagenicity due to imidazoquinoxaline heterocyclic amines. Addition of a reductone, ascorbate or erythorbate, at 0.3% to ground beef effectively reduced the mutagenicity of cooked hamburger. Mutagenicity of cooked hamburger was also decreased by addition of glucose at more than 0.7% to ground beef.

Topics: Amines; Animals; Anticarcinogenic Agents; Antimutagenic Agents; Antioxidants; Ascorbic Acid; Cattle; Food; Free Radical Scavengers; Free Radicals; Glucose; Heterocyclic Compounds; Hot Temperature; Imidazoles; Meat; Mutagens; Pyrazines; Quinoxalines

This study investigated the ability of the yeast Saccharomyces cerevisiae to synthesize ascorbate and its 5-carbon analogue erythroascorbate from a variety of precursors, and their importance as antioxidants in this organism. Studies of ascorbate and analogues in micro-organisms have been reported previously, but their function as antioxidants have been largely ignored. Ascorbate and erythroascorbate concentrations in yeast extracts were measured spectrophotometrically, and their levels and identity were checked using liquid chromatography-electrospray mass spectrometry. The yeast was readily able to synthesize ascorbate from L-galactono-1,4-lactone or erythroascorbate from D-arabinose and D-arabino-1,4-lactone, whereas L-gulono-1,4-lactone was a much poorer substrate for ascorbate biosynthesis. In untreated cells, the concentration of ascorbate-like compounds was below the level of detection of the methods of analysis used in this study (approximately 0.1 mM). Intracellular ascorbate and erythroascorbate were oxidized at high concentrations of tert-butylhydroperoxide, but not hydrogen peroxide. Their synthesis was not increased in response to low levels of stress, however, and preloading with erythroascorbate did not protect glutathione levels during oxidative stress. This study provides new information on the metabolism of ascorbate and erythroascorbate in S. cerevisiae, and suggests that erythroascorbate is of limited importance as an antioxidant in S. cerevisiae.

Topics: Arabinose; Ascorbic Acid; Chromatography, Liquid; Hydrogen Peroxide; Kinetics; Oxidants; Saccharomyces cerevisiae; Spectrometry, Mass, Electrospray Ionization; Stereoisomerism; Sugar Acids; tert-Butylhydroperoxide

D-Arabinono-1,4-lactone oxidase, which catalyzes the terminal step in the biosynthesis of D-erythroascorbic acid in Saccharomyces cerevisiae, was functionally expressed in Escherichia coli inherently lacking the enzyme. The recombinant E. coli strain expressing the enzyme could overproduce D-erythroascorbic acid and L-ascorbic acid when supplied with D-arabinono-1,4-lactone and L-galactono-1,4-lactone, respectively.

Topics: Ascorbic Acid; Escherichia coli; Recombinant Proteins; Saccharomyces cerevisiae; Sugar Alcohol Dehydrogenases

Analogs (6-deoxyascorbic acid, erythroascorbic acid, and associated glycosides) of L-ascorbic acid (AA) contained in mushrooms were allowed to react with hydrazine to form osazones, and the conditions for separative determination by HPLC using a Zorbax SIL column were examined. Separation was started using solvent system 1 (ethylacetate/n-hexane/acetone/acetic acid, 50:50:1:1, v/v) as the mobile phase, and switching after 15 min to solvent system 2 (ethylacetate/acetone/acetic acid, 100:1:1, v/v). Detection was performed by absorbance at 500 nm. Because these analogs showed different formation rates for osazone, calibration curves were prepared for each substance. The recovery rate in the load test was 93-105%. By this method, AA and the analogs contained in eight species of edible mushrooms have been determined. The results revealed that: (1) the main constituents of all mushrooms are AA analogs rather than AA itself; (2) only one species contained AA in a very small amount (2 mumol/kg); (3) the types of AA analogs present differed according to the species of mushrooms, and (4) the total amount of AA analogs was between ca. 100-500 mumol/kg (2-9 mg per 100 g, converted to AA). In addition, a new AA analog was found in Pleurotus ostreatus and identified as 5-O-(alpha-D-xylopyranosyl)-D-erythroascorbic acid in structural analyses by NMR and other methods.

Topics: Ascorbic Acid; Basidiomycota; Chromatography, High Pressure Liquid; Glycosides; Hydrazines; Magnetic Resonance Spectroscopy; Spectrophotometry

The interaction between dithranol and heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (TMBCyD) has been investigated in aqueous solution containing isoascorbic acid (0.2% w/v) as antioxidant and in the solid state. The interaction in the solid state was studied by differential scanning calorimetry (DSC), infrared spectroscopy (IR), X-ray powder diffractometry (XPD) and a dissolution-rate method. The extent of complexation between the two substances was poor, as indicated by the low value of the slope of the linear part of the solubility curve. A phase diagram was constructed by measuring the thermal behaviour of various re-solidified physical mixtures of dithranol and of TMBCyD previously subjected to heating until melting of the TMBCyD. The loss of dithranol, owing to sublimation and degradation caused by the thermal treatment used, was less than 10%. In keeping with XPD and IR data, the phase diagram indicated that a complex was formed containing 13.7% dithranol (molar ratio 1:1) which had a congruent melting point at 164 degrees C. The drug dissolution rate from the 1:1 complex was measurable, unlike that of the corresponding physical mixture, and was significantly increased when the complex was dispersed in the glassy matrix of TMBCyD, as it was in re-solidified mixtures containing 2-7% dithranol. The results show that the solubility of dithranol is increased significantly as a consequence of its interaction with TMBCyD, despite the low extent of complexation between the two substances.

Topics: Administration, Topical; Anthralin; Anti-Inflammatory Agents; Antioxidants; Ascorbic Acid; beta-Cyclodextrins; Calorimetry, Differential Scanning; Cyclodextrins; Microscopy, Polarization; Solubility; Solutions; Spectrophotometry, Infrared; X-Ray Diffraction

Dehydroascorbic acid, an oxidation product of ascorbic acid (vitamin C), spontaneously decomposed at neutral and higher pH levels to form three products that could be quantitated by HPLC-electrochemical analysis. One of the products was ascorbic acid, suggesting that dehydroascorbic acid was reduced to ascorbic acid without adding an exogenous reductant. The major newly produced compound was almost identical to ascorbic acid by UV spectroscopy, which therefore potentially interfered in the study of ascorbic acid metabolism. The ascorbic acid-like compound was isolated by reversed-phase HPLC and identified as L-erythroascorbic acid by mass spectrometry. Fe(II) and Cu(I) increased, whereas desferrioxamine, a potent iron chelator, inhibited L-erythroascorbic acid production. Phosphate, used as buffer, and cyanide greatly enhanced dehydroascorbic acid conversion to L-erythroascorbic acid. The identification of L-erythroascorbic acid and its quantitation by an electrochemical method provides a useful tool for future study of dehydroascorbic acid metabolism.

Topics: Ascorbic Acid; Chemical Phenomena; Chemistry, Physical; Chromatography, High Pressure Liquid; Copper; Deferoxamine; Dehydroascorbic Acid; Electrochemistry; Gas Chromatography-Mass Spectrometry; Hydrogen-Ion Concentration; In Vitro Techniques; Iron; Models, Chemical; Molecular Structure; Oxidation-Reduction; Solutions; Spectrophotometry, Ultraviolet

The validation of a rapid and selective stability-indicating high-performance liquid chromatographic procedure for the determination of rifampicin (RIF) and its decomposition products in aqueous solution is described. Direct injection and column switching HPLC procedures have been compared and, owing to the increased sensitivity and precision, the latter has been applied to the study of RIF stability in the presence of isoascorbic acid at pH 7.4. The time-dependent hydrolytic decomposition of RIF to 3-formyl rifamycin SV (RSV) was found to be biexponential. Log concentration versus time plots of RIF and RSV decomposition were found to be parallel, indicating a pseudo equilibrium decomposition process. This feature allowed corrections for the amounts lost to secondary reactions to be calculated when the assay was applied to the determination of release characteristics of RIF from biodegradable poly-d, l-lactide-co-glycolide microspheres.

Topics: Antibiotics, Antitubercular; Antioxidants; Ascorbic Acid; Biocompatible Materials; Chemistry, Pharmaceutical; Chromatography, High Pressure Liquid; Drug Stability; Hydrogen-Ion Concentration; Kinetics; Lactic Acid; Microspheres; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Polymers; Reproducibility of Results; Rifampin

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.

Topics: Amino Acids; Ascorbic Acid; Drug Design; Homocysteine; Homoserine; Indicators and Reagents; Methionine; Molecular Structure; Structure-Activity Relationship

The contents of ascorbic acid (AsA) and erythrobic acid (ErA) in the tissues of guinea pigs intraperitoneally injected with AsA and/or ErA were determined to learn the difference in their retention in the tissues. After 10 d of AsA depletion, the guinea pigs were intraperitoneally injected with 5 mg of AsA, or 5 mg of ErA, or 5 mg of each. At day 5 of repletion, the guinea pigs were killed and liver, adrenal glands, spleen, and kidneys were removed. AsA and ErA in these tissues were measured by using HPLC. The contents of AsA in the tissues of only the AsA-injected guinea pigs were similar to those of the AsA- + ErA-injected guinea pigs. The contents of ErA in the tissues of the ErA-injected guinea pigs were higher than those of the AsA- + ErA-injected guinea pigs, but apparently lower than the contents of AsA in the AsA-injected guinea pigs. ErA was scarcely retained in the tissues of guinea pigs.

Topics: Adrenal Glands; Alkaline Phosphatase; Aniline Hydroxylase; Animals; Antioxidants; Ascorbic Acid; Ascorbic Acid Deficiency; Body Weight; Chromatography, High Pressure Liquid; Cytochrome P-450 Enzyme System; Guinea Pigs; Injections, Intraperitoneal; Kidney; Liver; Male; Spleen; Stereoisomerism

D-Arabinose dehydrogenase was purified 843-fold from the cytosolic fraction of Saccharomyces cerevisiae with a recovery of 9%. The purified enzyme gave two bands with a molecular mass of 40 and 39 kDa on SDS-PAGE. The native enzyme had a molecular mass of 74 kDa as estimated by Sephacryl S-200 chromatography. Therefore, this enzyme was considered to be a heterodimer. The purified enzyme exhibited maximum activity at pH 10.0 and around 30 degrees C. The enzyme catalysed the oxidation of D-arabinose, L-xylose, L-fucose and L-galactose in the presence of NADP+. The apparent Km values at pH 10.0 with 50 microM NADP+ for D-arabinose, L-xylose, L-fucose, and L-galactose were 161, 24, 98 and 180 mM, respectively. The pH profile of Vmax and kcat/Km showed one ionisable groups around pH 8.3. D-Erythroascorbic acid was formed in vitro from D-arabinose by D-arabinose dehydrogenase and D-arabinono-1,4-lactone oxidase. The N-terminal amino acid sequence of the heavy subunit was Ser-Thr-Glu-Asn-Ile-Val-Glu-Asn-Met-Leu-His-Pro-Lys-Thr-. The N-terminus of the light subunit was blocked. The obtained peptide sequence was identical to the translational product of an unknown open reading frame, YBR149W, in chromosome II of S. cerevisiae. When compared with the translational product of this open reading frame, the peptide sequence was identical to the amino acid sequences of residues 7 to 20. The first six amino acids of this open reading frame were lost in protein sequence, which may be modified post-translationally. The heavy subunit was composed of 344 amino acid residues and its deduced amino acid sequence contained the motifs I, II, and III of aldo-keto reductase and also leucine zipper motif. This enzyme is the first heterodimeric protein of aldo-keto reductase family. In the deletion mutant of this gene, D-arabinose dehydrogenase activity and D-erythroascorbic acid were not detected.

Topics: Alcohol Oxidoreductases; Aldehyde Reductase; Aldo-Keto Reductases; Amino Acid Sequence; Arabinose; Ascorbic Acid; Base Sequence; Enzyme Stability; Hydrogen-Ion Concentration; Kinetics; Molecular Sequence Data; Saccharomyces cerevisiae; Sequence Alignment; Substrate Specificity; Sugar Alcohol Dehydrogenases; Temperature

Topics: Ascorbic Acid; Basidiomycota; Calorimetry; Catechols; Enzymes, Immobilized; Food Analysis; Hydroquinones; Laccase; Oxidoreductases; Substrate Specificity; Thermodynamics

D-Arabinono-1,4-lactone oxidase catalysing the final step of D-erythroascorbic acid biosynthesis was purified from the mitochondrial fraction of Saccharomyces cerevisiae. Based on the amino acid sequence analysis of the enzyme, an unknown open reading frame (ORF), YML086C, was identified as the ALO1 gene encoding the enzyme. The ORF of ALO1 encoded a polypeptide consisting of 526 amino acids with a calculated molecular mass of 59493Da. The deduced amino acid sequence of the enzyme shared 32% and 21% identity with that of L-gulono-1,4-lactone oxidase from rat and L-galactono-1,4-lactone dehydrogenase from cauliflower, respectively, and contained a putative transmembrane segment and a covalent FAD binding site. Blot hybridization analyses showed that a single copy of the gene was present in the yeast genome and that mRNA of the ALO1 gene was 1.8kb in size. In the alo1 mutants, D-erythroascorbic acid and the activity of D-arabinono-1,4-lactone oxidase could not be detected. The intracellular concentration of D-erythroascorbic acid and the enzyme activity increased up to 6.9-fold and 7.3-fold, respectively, in the transformant cells carrying ALO1 in multicopy plasmid. The alo1 mutants showed increased sensitivity towards oxidative stress, but overexpression of ALO1 made the cells more resistant to oxidative stress.

Topics: Amino Acid Sequence; Animals; Antioxidants; Ascorbic Acid; Gene Expression; Genes, Fungal; Hydrogen Peroxide; Molecular Sequence Data; Rats; Saccharomyces cerevisiae; Sugar Alcohol Dehydrogenases

D- and L-Ascorbic acids have been separated using liquid chromatography (LC) on a polymer-coated silica-based NH2 column and the L-isomer has been quantified in human serum, rat serum, rat lung, rat lung perfusate, infant formula (SRM 1846) and mixed food sample (SRM 2383). The D-isomer was observed only in trace amounts in the mixed food sample. The results demonstrate that ascorbic acid was stable on the column and completely recovered from supplemented samples of human serum and that this method of analysis is accurate, precise and has broad application exhibiting no dependence on the nature of the matrices evaluated herein.

Topics: Animals; Ascorbic Acid; Chromatography, Liquid; Dehydroascorbic Acid; Food, Formulated; Humans; In Vitro Techniques; Infant; Infant Food; Lung; Rats; Stereoisomerism

Topics: Animals; Ascorbic Acid; Cell Membrane; Dehydroascorbic Acid; Duodenum; Kinetics; Mice; NADH, NADPH Oxidoreductases

We describe here a simple and rapid capillary electrophoresis method for the determination of ascorbic acid (L-AA) and isoascorbic acid (D-AA) in vegetative tissues. For optimal yields and stabilization, samples are extracted with cold 3% metaphosphoric acid. Hydrophobic contaminants are then removed by passage through a C18 solid-phase extraction cartridge. The analysis itself is performed on a fused silica capillary with 200 mM borate, pH 9, as the carrier electrolyte, using on-line diode array detection over the range 190-350 nm. Quantitation was performed at 260 nm, the uv-absorption maximum for ascorbate at this pH. This method has a minimum detection limit of 84 fmol/injection and linearity of detector response was observed up to at least 12 pmol/injection. We also describe the influence of electrolyte concentration, pH, and the presence of detergent on separations of L-AA, D-AA, and L-galacturonic acid-1,4-lactone. The protocol has been demonstrated to be suitable for the analysis of L-AA in Arabidopsis, parsley, and mushroom. The method has superior resolution to comparable HPLC separations, a comparable analysis time, but lower sensitivity because of the concentration limitations of the detection system.

Topics: Arabidopsis; Ascorbate Oxidase; Ascorbic Acid; Basidiomycota; Chromatography, High Pressure Liquid; Electrophoresis, Capillary; Hydrogen-Ion Concentration; Plants; Reproducibility of Results; Sodium Dodecyl Sulfate

Topics: Absorption; Ascorbic Acid; Fruit; Humans; Nutrition Policy; Stereoisomerism; Vegetables

D-Arabinose dehydrogenase was purified 2750-fold from the cytosolic fraction of Candida albicans to apparent homogeneity, with an overall yield of 3%, by a purification procedure consisting of ammonium sulfate precipitation and DEAE-Sepharose A-50, Sephacryl S-200, Cibacron blue and phenyl-Sepharose CL-4B chromatographies. Gel-filtration chromatography gave an apparent molecular mass of 41 kDa and SDS-PAGE showed only one protein band corresponding to a molecular mass of 42 kDa, indicating that the enzyme is a single polypeptide. The enzyme was optimally active at pH 8.0 and the pI value of the enzyme was 5.0. The enzyme was relatively stable from pH 4.5 to 7.5. The optimal temperature for the enzyme activity was 30 degrees C. The activity of the enzyme was inhibited by Hg2+, Fe2+, Zn2+, Cu2+, Mg2+, Mn2+, N-ethylmaleimide and p-chloromercuribenzoic acid. The enzyme catalysed the oxidation of D-arabinose, L-fucose, L-xylose and L-galactose, which have the same configurations of hydroxyl groups at C2- and C3-positions, with apparent K(m) values of 29.2, 28.9, 37.1 and 91.3 mM at pH 8.0, respectively, with 50 microM NADP+. The enzyme used NADP+ as a coenzyme. Apparent K(m) value at 60 mM D-arabinose for NADP+ was 44.6 microM. NADPH inhibited the enzyme activity competitively with respect to NADP+ (Ki = 78.6 microM). The amino-terminal sequence of the enzyme was Met-Lys-Leu-Ala-Thr-Glu-Ile-Asp-Phe-X-Leu-Asn-Asn-Gly-. The reaction product was D-arabinono-1,4-lactone, judged from gas-liquid chromatography/mass spectrometry. In C. albicans, D-erythroascorbic acid was formed from D-arabinose by D-arabinose dehydrogenase and D-arabinono-1,4-lactone oxidase.

Topics: Amino Acid Sequence; Arabinose; Ascorbic Acid; Candida albicans; Cations, Divalent; Chloromercuribenzoates; Cytosol; Enzyme Inhibitors; Ethylmaleimide; Hydrogen-Ion Concentration; Isoelectric Point; Kinetics; Molecular Weight; Monosaccharides; NADP; Oxidation-Reduction; p-Chloromercuribenzoic Acid; Substrate Specificity; Sugar Alcohol Dehydrogenases; Temperature

The relative decrease in the 2 h accumulation of administered [3H]-spiperone (SPI)-2 muCi/kg, 0.0004 mg/kg, s.c. - in mouse corpus striatum, a brain area with a high dopaminergic input (specific plus nonspecific dopamine receptor ligand binding) and the cerebellum, a brain area with little, if any, dopaminergic input (an index of nonspecific dopamine receptor ligand binding) were used to compare the influence of araboascorbic acid (AraA) with ascorbic acid (AsA) on the dopamine receptor. The abilities of these compounds to potentiate haloperidol-induced catalepsy were also investigated. Pretreatment for 30 min with AraA (1000 or 2000 mg/kg, i.p.) produced the same dose-dependent decrease in SPI accumulation in corpus striatum as observed with AsA. Accumulation in cerebellum was unaffected by either agent. Furthermore, as previously shown for AsA in rats and monkeys, AsA (1000 mg/kg) potentiated the cataleptogenic effect of haloperidol (0.2 mg/kg, s.c.). AraA was at least as effective as AsA in potentiating catalepsy produced by the neuroleptic. Thus, it would appear that AraA influenced the dopamine receptor in a manner not unlike that already shown for AsA. Because both agents have almost identical redox potentials but divergent antiscorbutic activities, their reductive properties might be more pertinent to the observed effects than their antiscorbutic properties.

Topics: Animals; Ascorbic Acid; Catalepsy; Corpus Striatum; Dopamine; Dopamine Agents; Dopamine Antagonists; Dose-Response Relationship, Drug; Drug Synergism; Female; Haloperidol; Male; Mice; Neural Pathways; Spiperone

D-glycero-Pent-2-enono-1,4-lactone (trivial name: D-erythroascorbic acid) occurs in the phytopathogen, Sclerotinia sclerotiorum (Lib.) de Bary, where it has a potential role as precursor of oxalic acid. On Glc/yeast/malt medium, S. sclerotiorum produces only nominal amounts of D-erythroascorbic acid but even partial replacement of Glc by D-Ara increases production of erythroascorbic acid and oxalic acid. Use of D-[1-14C]-, -[3-14C]-, or -[6-14C]Glc and D-[5-3H]-, -[2-14C,5-3H]-, or -[UL-14C]Ara provide additional information on erythroascorbic acid biosynthesis and cleavage. The latter process resembles that obtained by peroxygenation of erythroascorbic acid in alkaline solution. An unknown erythroascorbic acid-like compound also occurs in both Glc- and Ara-based cultures.

Topics: Arabinose; Ascomycota; Ascorbic Acid; Biotransformation; Carbon Radioisotopes; Chromatography, High Pressure Liquid; Glucose; Oxalates; Oxalic Acid; Radioisotope Dilution Technique; Tritium

The vitamin C activity of erythorbic acid (ErA) in ascorbic acid (AsA)-deficient guinea pigs was evaluated. The guinea pigs depleted AsA for 16 days were divided into two groups: one group (control group) was supplemented with 1, 5, or 100 mg/day AsA and the other group (experimental group) was supplemented with 1, 5, 20, or 100 mg/day ErA for 4 days. The contents of AsA and ErA in the tissues of guinea pigs were determined by using HPLC, and the activities of liver aniline hydroxylase, of serum alkaline phosphatase and the content of liver cytochrome P-450 were measured. The AsA tissue content of AsA-supplemented guinea pigs was much higher than the ErA tissue content of ErA-supplemented ones, and also, the activities of liver aniline hydroxylase, of serum alkaline phosphatase and the content of liver cytochrome P-450 of AsA-supplemented animals were much higher than those of ErA-supplemented animals, even when the supplemented amount of ErA was equal to that of AsA. Based on these results, the vitamin C activity of ErA seems to be much lower than that of AsA in the AsA-deficient guinea pigs. This suggested that the apparent vitamin C activity of ErA was dependent on the AsA tissue levels of guinea pigs.

Topics: Adrenal Glands; Alkaline Phosphatase; Aniline Hydroxylase; Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Body Weight; Chromatography, High Pressure Liquid; Cytochrome P-450 Enzyme System; Guinea Pigs; Liver; Male; Stereoisomerism

It has been suggested that the host antimalarial response depends in part on phagocyte-derived oxidants and that the parasite itself exerts an oxidative stress on its erythrocytic environment. Intraerythrocytic malaria parasites are particularly susceptible to being damaged by oxidative drugs, several of which are under development as chemotherapeutic agents. Thus the antioxidant status and associated regulatory mechanisms of the blood during malaria infection are of great interest. The important antioxidant ascorbate (AH-) and isoascorbate (IAH-), an isomer that does not occur naturally in animals, were found to have similar redox properties. We therefore assessed the usefulness of IAH- as a marker for studies of AH- handling in vivo and in vitro under normal conditions and in murine malaria infection. DHIA added to whole blood from normal or Plasmodium vinckei-infected mice in vitro was rapidly taken up into blood cells and reduced to IAH-. Intracellular IAH- derived from the exogenous DHIA was released into the plasma by blood cells from malaria-infected mice but not those from normal mice. Uptake and reduction of DHIA had no effect on plasma or cellular levels of AH- under these conditions. IAH- injected i.v. into either normal or P. vinckei-infected mice was rapidly cleared in both cases and led to an increase in plasma levels of AH-; this suggested displacement of the latter from some intracellular site, presumably not associated with blood cells. DHIA administered as an intravascular bolus into either normal or malaria-infected mice was rapidly reduced. However, in contrast to the in vitro situation, the concentration of plasma IAH- derived from the injected DHIA was approximately the same in both the infected and control animals. The IAH- so formed disappeared quickly from the plasma. Intravenous injection of DHIA into malaria-infected mice caused a rapid, prolonged increase in the proportion of plasma vitamin C in the form of DHA, whereas in uninfected mice there was a transient decrease in plasma DHA followed by normalisation. The changes in plasma AH- and DHA following IV injection of a single dose of DHA closely paralleled those seen after DHIA administration. These observations indicate that: (i) blood cells from normal and malaria-infected mice take up and reduce DHIA in a similar fashion, but they have different ways of handling the resulting IAH-; (ii) cells other than blood cells are important in the reduction of plasma DHIA and DHA in vi

Topics: Animals; Antioxidants; Ascorbic Acid; Biomarkers; Dehydroascorbic Acid; Erythrocytes; Female; Free Radicals; In Vitro Techniques; Malaria; Mice; Mice, Inbred CBA; Oxidation-Reduction; Reactive Oxygen Species; Stereoisomerism

D-Erythroascorbic acid was detected from the cell extracts of a dimorphic fungus, Candida albicans. Its concentration in yeast cells grown at 25 degrees C was estimated to be about 0.45 mumol/ml cell water. D-Arabinono-1,4-lactone oxidase, which catalyses the final step in the biosynthesis of D-erythroascorbic acid, was purified 639-fold from the mitochondrial fraction of C. albicans to apparent homogeneity, with an overall yield of 21.2%, by a purification procedure consisting of Triton X-100 solubilisation, ammonium sulphate precipitation, anion-exchange, hydrophobic-interaction, gel-filtration and dye-ligand chromatographies. Gel-filtration chromatography and polyacrylamide-gradient gel electrophoresis in the presence of deoxycholate gave apparent molecular masses of 110 kDa and 84.4 kDa, respectively. SDS/PAGE showed only one protein band corresponding to a molecular mass of 66.7 kDa. Considering the binding of detergents, the enzyme is suggested to be a single polypeptide. The enzyme showed a typical fluorescence excitation spectrum of a flavin-containing enzyme. The flavin was not released by treatment with SDS, CCl3CO2H or boiling, indicating that it may be covalently bound to the enzyme protein. The enzyme was optimally active at 40 degrees C and at pH 6.1. The enzyme was stable in the range pH 7.5-10. An apparent Km value for D-arabinono-1,4-lactone was 44.1 mM. L-Galactono-1,4-lactone, L-gulono-1,4-lactone and L-xylono-1,4-lactone could also serve as substrates. Competitive inhibition was demonstrated with D-glucono-1,5-lactone, L-arabinono-1,4-lactone, D-galactono-1,4-lactone and D-gulono-1,4-lactone. p-Chloromercuribenzoate, N-ethylmaleimide, iodoacetic acid, iodoacetamide and divalent metal ions such as Cd2+, Hg2+, Mn2+ and Zn2+ exhibited inhibitory effects on the enzyme.

Topics: Ascorbic Acid; Binding, Competitive; Candida albicans; Enzyme Stability; Hydrogen-Ion Concentration; Kinetics; Mitochondria; Molecular Weight; Substrate Specificity; Sugar Alcohol Dehydrogenases; Temperature

Ascorbic acid inhibited the specific binding of both the D1 agonist, [3H] SKF 38393, and the D2 agonist, [3H] N-0437 at physiologically relevant concentrations. This inhibition was both stereospecific and receptor selective. Using ligand concentrations approximating their KD's, the IC50's for ascorbate and two structural analogues, isoascorbate and D-glucoascorbate, were determined. The rank order of IC50's at both D1 and D2 were D-glucoascorbate greater than isoascorbate greater than ascorbate. However, the IC50 for each compound was greater at D1 than D2. Evaluation of the relationship between the IC50 for ascorbate and the ligand concentration using both the D1 and the D2 ligand yielded data inconsistent with competitive inhibition models. Preliminary experiments were conducted to evaluate the site and type of inhibition with results consistent with an allostearic effect at the level of the receptor.

Topics: 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; Animals; Ascorbic Acid; Corpus Striatum; Dopamine Agents; Heptoses; Kinetics; Ligands; Male; Rats; Receptors, Dopamine; Stereoisomerism; Tetrahydronaphthalenes; Thiophenes

Ultraviolet radiation damage to the skin is due, in part, to the generation of reactive oxygen species. Vitamin C (L-ascorbic acid) functions as a biological co-factor and antioxidant due to its reducing properties. Topical application of vitamin C has been shown to elevate significantly cutaneous levels of this vitamin in pigs, and this correlates with protection of the skin from UVB damage as measured by erythema and sunburn cell formation. This protection is biological and due to the reducing properties of the molecule. Further, we provide evidence that the vitamin C levels of the skin can be severely depleted after UV irradiation, which would lower this organ's innate protective mechanism as well as leaving it at risk of impaired healing after photoinduced damage. In addition, vitamin C protects porcine skin from UVA-mediated phototoxic reactions (PUVA) and therefore shows promise as a broad-spectrum photoprotectant.

Topics: Administration, Topical; Animals; Antioxidants; Ascorbic Acid; Male; Regional Blood Flow; Skin; Skin Absorption; Sunburn; Ultraviolet Rays

Topics: Animals; Ascorbic Acid; Brain Chemistry; Cerebral Ventricles; Chromatography, High Pressure Liquid; Dialysis; Electrochemistry; Male; Rats; Rats, Inbred Strains; Uric Acid

Topics: Ascorbic Acid; Chromatography, High Pressure Liquid; Female; Humans; Male

Both the ascorbic acid (AsA) and erythorbic acid (ErA) absorption in the small intestine of guinea pigs were determined by the perfusion of the small intestine using isotonic phosphate buffer recycled in situ. The absorption rate of AsA in the small intestine of guinea pigs was higher than that of ErA; however, Km of AsA absorption was lower than that of ErA in normal guinea pigs. In AsA-deficient guinea pigs, the absorption rates of both AsA and ErA were higher than those in normal ones. The absorption of AsA and ErA in the small intestine of guinea pigs was inhibited by ouabain. Furthermore, AsA and ErA inhibited each other's absorption. Based on the results, the net amount of the absorbed ErA in the small intestine may be lower than that of AsA, and ErA absorption mechanism seemed to be similar to that of AsA. The absorption rate of both AsA and ErA in the small intestine of guinea pig might be dependent on the AsA level in the tissues.

Topics: Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Guinea Pigs; In Vitro Techniques; Intestinal Absorption; Intestine, Small; Male; Perfusion

Ascorbate irreversibly inhibited morphological transformation induced by methylcholanthrene in C3H/10T1/2 cells. To determine the mechanisms of this inhibition, we studied ascorbate uptake, redox potential, matrix proteins, and lipid composition of 10T1/2 cells. Ascorbate (16.8 nmol/dish) saturated cells and reduced the NADH-to-NAD+ ratio. Daily treatments with ascorbate, 28 nmol/dish, maintained intracellular ascorbate and reduced NADH by half. Matrix collagen and glycoproteins were stimulated by ascorbate, Iso-ascorbate, and dehydroascorbate in a dose-dependent manner. Both ascorbate and dehydroascorbate reduced total lipids with time; neutral lipids increased but were released into the media, phospholipids were modified, cholesterol-phospholipid ratios declined, and an inverse relationship between unsaturation index and cholesterol-phospholipids was apparent. Lipophilic bodies gradually accumulated. Our data suggest that inhibition of transformation by ascorbate, Iso-ascorbate, or dehydroascorbate may be associated with regulation of the redox potential, glycoproteins, and lipids in 10T1/2 cells.

Topics: Animals; Ascorbic Acid; Cell Line; Cell Transformation, Neoplastic; Dehydroascorbic Acid; Methylcholanthrene; NAD; Oxidation-Reduction

D-Erythorbic acid is an epimer of L-ascorbic acid, but lacks antiscorbutic activity. It is commonly used as a food additive, particularly in processed meat items. Except for high-performance liquid chromatography (HPLC) methodology, the commonly used analytical procedures to measure vitamin C do not distinguish between the two isomers. A study with seven adult women demonstrated that the concentration of erythorbic acid present in food items commonly consumed was sufficient to produce interference in plasma vitamin C analyses. With the meals used, 7-23% of the apparent vitamin C in plasma obtained 2 h after the ingestion of the meals was actually erythorbic acid when analyzed by HPLC. To avoid falsely high plasma-serum vitamin C values as a result of erythorbic acid ingestion, the analyses should be conducted on overnight fasting blood specimens or with the use of an HPLC-amperometric method.

Topics: Adult; Ascorbic Acid; Diet; Eating; Fasting; Female; Humans; Middle Aged; Stereoisomerism

Isolated kidney cells accumulated L[1-14C]ascorbic acid in a time-dependent manner and reached a steady state after 15 min at 37 degrees C. Initial velocity for uptake was over 300 pmol/mg protein per min when cells were separated from the bathing solution using a density gradient established during centrifugation. The uptake process was saturable with an apparent concentration at half maximal uptake of 36 mumols/L. Ascorbate uptake was reduced by metabolic inhibitors and was temperature dependent. Although ascorbic acid is an acid anion at pH 7.4, uptake did not appear to be inhibited by other acid anions such as p-aminohippurate and probenecid; however, involvement of the ion gradient established by Na+, H(+)-adenosine triphosphatase could not be confirmed. Replacing the sodium ion with other monovalent ions reduced the accumulation of ascorbate significantly. Isoascorbic and dehydroascorbic acids inhibited ascorbate uptake (34 and 13 mmol/L, respectively), whereas high concentrations of glucose showed some stimulation. These findings indicated that ascorbic acid is reabsorbed by the kidney in a sodium-dependent active transport process that is not common to other acid anions and has some specificity for the ascorbic acid structure.

Topics: Adenosine Triphosphate; Animals; Ascorbic Acid; Biological Transport; Carbon Radioisotopes; Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; Cell Separation; Centrifugation, Density Gradient; Chromatography, High Pressure Liquid; Dehydroascorbic Acid; Glucose; Hydrogen-Ion Concentration; Kidney; Kinetics; Male; Ouabain; Rats; Sodium

The dehydrogenase activity of dimeric dihydrodiol dehydrogenases (DD) purified from pig and rabbit lenses was inhibited by either L-ascorbic acid or its epimer, isoascorbic acid, at pH 7.5. Isoascorbate [IC50 (concn. giving 50% inhibition) = 0.043 mM for the pig enzyme; IC50 = 0.13 mM for the rabbit enzyme] was a more potent inhibitor than ascorbate (IC50 values 0.45 and 0.90 mM respectively), but 1 mM-dehydroascorbate gave less than 30% inhibition. Glucose, glucuronate, gulono-gamma-lactone, glutathione and dithiothreitol did not inhibit the enzyme activity. The inhibition by isoascorbate and ascorbate was instantaneous and reversible, and their inhibitory potency was decreased by addition of ascorbate oxidase. In the reverse reaction, isoascorbate and ascorbate gave low IC50 values of 0.013 and 0.10 mM respectively for the pig enzyme and 0.025 and 0.25 mM for the rabbit enzyme. The inhibition patterns by the two compounds were competitive with respect to dihydrodiols of naphthalene and benzene and uncompetitive with respect to NADP+, but those in the reverse reaction were uncompetitive with respect to both carbonyl substrate and NADPH. The steady-state kinetic measurements in the forward and reverse reactions by the pig enzyme were consistent with an ordered Bi Bi mechanism, in which NADP+ binds to the enzyme first and NADPH leaves last. The results indicate that ascorbate and its epimer directly bind to an enzyme: NADP+ binary complex as dead-end inhibitors. Thus ascorbate may be an important modulator of DD in the lens.

Topics: Alcohol Oxidoreductases; Animals; Ascorbic Acid; Binding, Competitive; Hydrogen-Ion Concentration; Kinetics; Lens, Crystalline; Macromolecular Substances; NADP; Oxidoreductases; Oxidoreductases Acting on CH-CH Group Donors; Rabbits; Swine

Topics: Ascorbic Acid; Cell Line; Collagen; Culture Media; Fibroblasts; Humans; Kinetics; Skin; Time Factors

The nitric oxide (NO) reductase activity of the cytoplasmic membrane of Paracoccus denitrificans can be solubilized in dodecyl maltoside with good retention of activity. The solubilized enzyme lacks NADH-dependent activity, but can be assayed with isoascorbate plus 2,3,5,6-tetramethylphenylene-1,4-diamine as electron donor and with horse heart cytochrome c as mediator. Reduction of NO was measured with an amperomeric electrode. The solubilized enzyme could be separated from other electron-transport components, including the cytochrome bc1 complex and nitrite reductase, by several steps of chromatography. The purified enzyme had a specific activity of 11 mumols.min-1.mg of protein-1 and the Km(NO) was estimated as less than 10 microM. The enzyme formed N2O from NO with the expected stoichiometry. These observations support the view that NO reductase is a discrete enzyme that participates in the denitrification process. The enzyme contained both b- and c-type haems. The former was associated with a polypeptide of apparent molecular mass 37 kDa and the latter with a polypeptide of 18 kDa. Polypeptides of 29 and 45 kDa were also identified in the purified protein which showed variable behaviour on electrophoresis in polyacrylamide gels.

Topics: Ascorbic Acid; Catalysis; Cell Membrane; Chromatography; Cytochrome c Group; Detergents; Electron Transport; Electrophoresis, Polyacrylamide Gel; Glucosides; Kinetics; Molecular Weight; NAD; Nitric Oxide; Oxidation-Reduction; Oxidoreductases; Paracoccus denitrificans; Solubility; Spectrophotometry; Tetramethylphenylenediamine

The enzyme activities, which are influenced by the vitamin C level in tissues, were measured to evaluate the vitamin C activity of erythorbic acid (ErA) in guinea pigs administered ErA. Guinea pigs were divided into two groups: animals in one group (control group) were administered 1, 5, and 100 mg/day ascorbic acid (AsA) and those in the other group (supplemented group) were administered 1, 5, 20, and 100 mg/day ErA for 16 days. At the end of the experimental period, they were sacrificed, blood was collected, and their livers were removed. The activities of liver aniline hydroxylase, of liver acid phosphatase, and of serum alkaline phosphatase, and the content of liver cytochrome P-450 were assayed. The activities of aniline hydroxylase and serum alkaline phosphatase and the content of liver cytochrome P-450 of the guinea pigs administered 1 mg ErA were lower than those of the guinea pigs administered 1 mg AsA. However, the enzyme activities and liver cytochrome P-450 content in the guinea pigs administered 5 mg or more of ErA were similar in level to those in the guinea pigs administered 5 mg AsA. These results suggested that administration of a considerably high amount of ErA to guinea pigs showed a similar vitamin C activity to that of AsA, which might suggest that vitamin C activity of ErA may be more than one-twentieth that of AsA, as has been generally believed.

Topics: Acid Phosphatase; Alkaline Phosphatase; Aniline Hydroxylase; Animals; Antioxidants; Ascorbic Acid; Cytochrome P-450 Enzyme System; Guinea Pigs; Liver; Male

In contrast to most biologically active molecules, the isomeric form of ascorbate retains significant biological activity. Moreover, in studies in vitro the isomer was found to be an equally effective cofactor in the enzymatic proline hydroxylation reaction. This raises questions about whether the lower biological activity in vivo results from selective transport into the cell, greater instability of the molecule, or stereospecificity by certain enzyme complexes. Distinguishing these possibilities can be accomplished most directly using a cell culture model. In this study primary avian tendon (PAT) cells were used. With PAT cells isoascorbate was shown to be three- to fivefold less active at inducing procollagen production than ascorbate. Isoascorbate was also internalized by the cell at about one-fifth the ascorbate level. In addition, isoascorbate was degraded in the medium at a slightly higher rate (half-life of 1.6 h) than ascorbate (2.1 h). The data are consistent with a model that postulates that once inside the cell isoascorbate is equally effective at inducing procollagen production but selectivity at the transport step restricts the percentage that is actually internalized. In addition, both ascorbate and isoascorbate were found to degrade very quickly inside the cell in the highly oxygenated environment of cell culture (approximately 2 h half-life). When ascorbate was added to the medium (100 micrograms/mL) the level inside the cell quickly reached a maximum (less than 2 h) and declined rapidly.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Ascorbic Acid; Cells, Cultured; Chick Embryo; Collagen; Drug Stability; Procollagen; Regression Analysis; Stereoisomerism; Tendons

Sodium erythorbate (SE) was administered at concentrations of 0, 1.25, or 2.5% (maximum tolerated dose, MTD) in the drinking-water to groups of 50 male B6C3F1 mice respectively. Female groups, each consisting of 50 mice, received SE in the drinking-water at concentrations of 0, 2.5 or 5% (MTD). Treatment continued for 96 wks and the experiment was terminated during wk 110. Tumors were observed at various sites including the liver, hematopoietic system, lung and soft tissue. However, at any of the sites, the tumor incidence, the time to death with tumors or the histological distribution of tumors did not differ significantly from those in the untreated control group. Thus, the present study did not demonstrate a tumorigenic effect of SE on B6C3F1 mice by means of oral administration.

Topics: Administration, Oral; Animals; Antioxidants; Ascorbic Acid; Carcinogenicity Tests; Carcinogens; Female; Male; Mice

The effect of exogenous ascorbic acid intake on biosynthesis of ascorbic acid in mice has been studied. After the mice were on diets containing added ascorbic acid for two months, the activities of ascorbic acid synthesizing enzymes in the mouse liver homogenates were measured using L-gulono-gamma-lactone as a substrate. Exogenous ascorbic acid intake (0.5, 1 or 5% in the diet) was able to increase the concentration of ascorbic acid in the blood and to decrease the activities of ascorbic acid synthesizing enzymes in mouse liver. The results suggest that ascorbic acid synthesis was controlled by local regulatory mechanism or by the concentration of ascorbic acid in the hepatic portal blood. Ingestion of dietary erythorbic acid, a stereoisomer of ascorbic acid, had no effect on the activities of ascorbic acid synthesizing enzymes.

Topics: Animals; Ascorbic Acid; Diet; Female; Liver; Male; Mice; Mice, Inbred C57BL; Sex Factors; Stereoisomerism

The thermal inactivation of Salmonella thompson, Escherichia coli, Staphylococcus aureus, Clostridium perfringens, Candida zeylanoides, Enterococcus faecium and E. faecalis was accelerated by the addition of sodium isoascorbate (1 mmol/l) to phosphate-buffer heating medium but not to complex food mixtures. The lethal effect of isoascorbate was nullified by heating under anaerobic conditions or by the addition of catalase. The scavengers of hydroxyl radicals, mannitol and formate were not protective whereas histidine was. Histidine may have protected by slowing the rate of isoascorbate autoxidation, a property common to other amino acids tested. Superoxide dismutase was not protective. Dehydroascorbic acid also enhanced heat killing and its action was also reversed by catalase. The bactericidal effects of mild heat plus isoascorbate or dehydroascorbic acid both apparently depend on oxidative processes but their relative effectiveness was not related to their respective rates of oxygen consumption or peroxide production. We speculate that site-specific redox reactions, involving amino-carbonyl intermediates are involved in the inactivation mechanism.

Topics: Anaerobiosis; Antioxidants; Ascorbic Acid; Bacteria; Catalase; Chromatography, High Pressure Liquid; Colony Count, Microbial; Dehydroascorbic Acid; Histidine; Hot Temperature; Magnesium; Oxidation-Reduction; Oxygen Consumption; Salmonella; Stereoisomerism; Superoxide Dismutase

The effect of erythorbic acid (ErA) administration on activities of liver aniline hydroxylase, liver acid phosphatase, and serum alkaline phosphatase, and the content of liver cytochrome P-450 was studied to determine whether or not ErA would affect the availability of ascorbic acid (AsA) in normal and AsA-deficient guinea pigs. In experiment I, changes of the enzyme activities and liver cytochrome P-450 content in the guinea pigs administered AsA and/or ErA and sacrificed on days 4, 10, 16, and 30 were examined. Moreover, in experiment II, after 16 days of depletion of AsA, the guinea pigs were administered AsA and/or ErA. These animals were sacrificed on days 0, 4, and 20 of the repletion period, after which the activities of drug metabolic enzyme and phosphatases and content of cytochrome P-450 during recovery were observed. The enzyme activities and cytochrome P-450 content of AsA-supplemented guinea pigs were similar to those of ErA-supplemented animals and also similar to those of both AsA and ErA-supplemented guinea pigs throughout the experimental period. During the repletion of the AsA-depleted guinea pigs, there were no significant differences in these enzyme activities and cytochrome P-450 content among the animals administered AsA and/or ErA. These results suggested that ErA administration may not affect the AsA availability in the guinea pigs.

Topics: Acid Phosphatase; Alkaline Phosphatase; Aniline Hydroxylase; Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Cytochrome P-450 Enzyme System; Guinea Pigs; Liver; Male

Ascorbic acid (AA) metabolism and requirements were studied in 11 adult nonpregnant women maintained in a metabolic unit and fed a formula diet devoid of AA for 54 d. After depletion for 24 d, the subjects received increasing supplements of AA in the presence or absence of 600 mg/d of erythorbic acid (EA). Various analytical procedures were used to measure AA concentrations in blood components. The depletion period resulted in a marked decrease in AA in all blood indices. During the study scorbutic signs developed in some of the subjects. AA supplements of 30 mg/d for 10 d failed to increase plasma ascorbate concentrations; 60 mg/d for 10 d produced a small increase; 90 mg/d resulted in a mean AA concentration of 29 mumol/L. EA did not present any adverse effects, but rather had a small sparing effect. Vitamin C requirements for adult nonsmoking, nonpregnant women would be marginally met by an intake of 60 mg/d of AA whereas 90 mg/d would provide an allowance for body storage.

Topics: Adult; Ascorbic Acid; Ascorbic Acid Deficiency; Blood Specimen Collection; Chromatography, High Pressure Liquid; Diet; Energy Metabolism; Female; Humans; Leukocytes; Nutritional Requirements; Nutritional Status

The high level of ascorbic acid (AA) in the aqueous humor of many mammals suggests an active transport of AA across the double-layered ciliary epithelium from blood to aqueous humor. We used [14C]AA to study AA uptake in bovine pigmented ciliary epithelial cells in tissue culture. We observed a 40-fold intracellular accumulation of AA, which was dependent on extracellular Na+. With labeled dehydroascorbate (DHA, the oxidized form of the vitamin) in the medium, there was a 20-fold intracellular accumulation of the label. However, the time course of DHA uptake was different compared with AA uptake and was not Na+ dependent, suggesting different transport systems for AA and DHA. AA uptake was inhibited by 1 mM phloretin and in the presence of isoascorbate. Furthermore, AA uptake was markedly reduced when intracellular Na+ was elevated by preincubation with ouabain or amphotericin B. With increasing AA concentration, Na+-dependent AA uptake exhibited first-order saturation kinetics with half-maximal uptake at 76 microM AA. Na+ dependence of AA uptake revealed a sigmoidal curve of Na+-dependent AA uptake vs. Na+ concentration with a half-maximal AA uptake at 45.4 mM Na+. The slope of the Hill plot from these data was 1.94, suggesting a transport system translocating two or more Na+ for one AA. This stoichiometry implies electrogenicity of the transporter. We, therefore, measured membrane potentials using conventional microelectrodes. Addition of 200 microM AA resulted in a depolarization of the membrane voltage by 4.9 +/- 0.5 mV (n = 22), which was absent in Na+ free medium and was markedly reduced by phloretin.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Amphotericin B; Animals; Ascorbic Acid; Biological Transport, Active; Cattle; Cells, Cultured; Ciliary Body; Dehydroascorbic Acid; Electrochemistry; Epithelium; Kinetics; Membrane Potentials; Ouabain; Phloretin; Pigmentation; Sodium

We show here that cultured neonatal-rabbit aortic smooth-muscle cells produce and accumulate significant amounts of insoluble elastin. When grown in the presence of ascorbic acid, the amount of insoluble elastin in these cultures decreases, whereas the accumulation of collagen increases. These changes have been attributed to increased hydroxylation of proline in elastin. The function of ascorbic acid in proline hydroxylation is thought to be that of a reductive cofactor that maintains the proper oxidation state of molecular iron in the enzyme complex. This study shows that both ascorbic and isoascorbic acids act similarly to modify the accumulation of elastin and collagen in culture. On the other hand, cultures grown in the presence of dithiothreitol, a reducing agent previously shown to act as a cofactor for prolyl hydroxylase, do not demonstrate altered elastin accumulation. These studies are consistent with the suggestion that there is a specific role for ascorbic acid in this cellular system that cannot be replaced by other reducing cofactors.

Topics: Amino Acids; Animals; Ascorbic Acid; Cells, Cultured; Collagen; Dithiothreitol; Dose-Response Relationship, Drug; Elastin; Muscle, Smooth, Vascular; Oxidation-Reduction; Rabbits

The growth of Bacillus cereus is a problem in liver sausage especially when the sausages are stored at high temperatures. Even concentrations of greater than 10(6)/g have been detected. In this study we found that when combining glucono-delta-lactone, sodium erythorbate and citric acid with sodium nitrite and salt the growth of B. cereus could be delayed or totally inhibited.

Topics: Animals; Ascorbic Acid; Bacillus cereus; Citrates; Citric Acid; Food Microbiology; Food Preservation; Gluconates; Lactones; Liver; Meat; Meat Products; Sodium Nitrite; Swine; Temperature

The chemical structure of dopamine includes an ortho-catechol group which is labile to oxidizing agents. Ascorbic acid, a reducing agent, has in the past been added to the incubation medium in order to protect dopamine against oxidation. However, there has been no thorough examination of the biological effect of ascorbic acid on prolactin release. In this present study we have shown that ascorbic acid has neither a stimulatory nor an inhibitory effect on prolactin release but reduces by approximately two orders of magnitude the concentration of dopamine necessary to inhibit prolactin release from cultured anterior pituitary cells. The strong potentiation effect of ascorbic acid was reproduced using apomorphine. We compared the effect of ascorbic acid and isoascorbic acid on dopamine inhibition of prolactin release. Isoascorbic acid is an epimer of ascorbic acid, having the same reduction-oxidation potential as ascorbic acid, but is less biologically active. Isoascorbic acid was less effective in potentiating the dopaminergic effect than was ascorbic acid, which supports the notion that potentiation by ascorbic acid is not entirely due to its reducing property. In order to dissociate further the chemical protection of dopamine from the biological potentiation, the inhibitory effects of freshly made and 3-h-old dopamine solutions were compared. Neither one of the two solutions contained any ascorbic acid, yet the two solutions did not show any difference in their ability to inhibit prolactin release during the 3-h incubation period, indicating that no significant amount of dopamine was oxidized.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Apomorphine; Ascorbic Acid; Cells, Cultured; Depression, Chemical; Dopamine; Dose-Response Relationship, Drug; Drug Synergism; Male; Pituitary Gland; Prolactin; Rats; Rats, Inbred Strains

The enzyme activities which depended on the ascorbic acid (AsA) tissue levels were assayed to investigate the effect of erythorbic acid (ErA) administration on the AsA availability in the guinea pigs administered 5 mg of AsA/day or 1 mg of AsA/day. The guinea pigs were given 5 mg of AsA and 1, 5, 20, 100 mg of ErA/day, or 1 mg of AsA and 1 or 20 mg of ErA/day for 16 days. The animals were sacrificed, blood was collected, and their livers were removed. The activities of liver aniline hydroxylase, liver acid phosphatase, and serum alkaline phosphatase, as well as the liver cytochrome P-450 content were measured. These enzyme activities and the liver cytochrome P-450 content of animals administered 5 mg of AsA seemed to show no change regardless of ErA supplement. Animals administered 1 mg of AsA showed different activities of liver aniline hydroxylase and liver acid phosphatase compared with those of animals administered 5 mg of AsA; however, the enzyme activities in animals administered 20 mg of ErA together with 1 mg of AsA were similar to those of the animals administered only 5 mg of AsA. These results indicated that ErA administration had no effect on the enzyme activities and the liver cytochrome P-450 content in the 5 mg AsA-supplemented animals, but administration of 20 mg of ErA was effective to maintain at normal levels the activities of liver aniline hydroxylase and liver acid phosphatase in the 1 mg AsA-supplemented animals.

Topics: Acid Phosphatase; Alkaline Phosphatase; Aniline Hydroxylase; Animals; Ascorbic Acid; Body Weight; Cytochrome P-450 Enzyme System; Guinea Pigs; Liver; Male

The transepithelial transport of ascorbate across the isolated rabbit ciliary epithelium (CE) was investigated. Unidirectional 14C-ascorbate fluxes were measured in the presence of equal concentrations of ascorbate on both sides of the tissue within the range of 0.025 to 1 mM. The blood to aqueous (Bl----Aq) flux increased from 6 to 95 nmoles/hr and showed nonlinearity and saturation. The aqueous to blood (Aq----Bl) flux increased, for the same range, from 0.5 to 23 nmoles/hr in a linear fashion. The permeability calculated from the Aq----Bl flux was similar to the CE permeability for mannitol suggesting that the Aq----Bl flux is mainly paracellular. The flux ratio Bl----Aq/Aq----Bl was between 4 to 12. Anoxia, ouabain and low Na+ in the media inhibited the Bl----Aq flux indicating that the transport system requires energy and a Na+ gradient. 3-O-methyl-D-glucose, D-isoascorbic acid and phlorizin also inhibited the Bl----Aq flux, suggesting that ascorbate and glucose may share a common carrier mechanism. Although the isolated CE preparation was clearly capable of flux separation and active transport, the rate of ascorbate transport measured in vitro is insufficient to maintain the aqueous ascorbate concentration observed in vivo.

Topics: 3-O-Methylglucose; Amphotericin B; Animals; Aqueous Humor; Ascorbic Acid; Biological Transport, Active; Blood; Cell Membrane Permeability; Ciliary Body; Epithelium; Female; Hypoxia; In Vitro Techniques; Methylglucosides; Osmolar Concentration; Phlorhizin; Rabbits

Topics: Ascorbic Acid; Beverages; Chromatography, High Pressure Liquid; Fruit; Hydrogen-Ion Concentration; Oxidation-Reduction

UDPglucuronic acid and erythroascorbic acid were identified in extracts of the fungus Neurospora crassa. The concentrations of these two compounds are estimated, in growing wild type N. crassa, to be about 0.10 and 0.28 mumol/ml of cell water, respectively. The pools of these two compounds are regulated by cyclic AMP in Neurospora, both being elevated in the cr-1, adenylate cyclase deficient mutant and both being lowered by exogenous cyclic AMP. The pools of these two compounds are also elevated on nitrogen deprivation. The pools of a large number of other nucleotides are not influenced by cyclic AMP. Possible relationships between the metabolism of UDPglucuronic acid and erythroascorbic acid are discussed. It was found that exogenous cyclic AMP was much more effective in influencing cultures grown at 30-37 degrees C than those grown at 25 degrees C. We suggest that higher temperatures may render Neurospora more permeable to a variety of different compounds.

Topics: Adenylyl Cyclases; Ascorbic Acid; Chromatography, High Pressure Liquid; Cyclic AMP; Neurospora; Neurospora crassa; Nucleotides; Temperature; Uridine Diphosphate Glucuronic Acid

High-performance liquid chromatography on two Asahipak GS-320 hydrophilic gel columns (50 X 0.76 cm I.D.), connected in series, with 0.015 M tartrate buffer (pH 3.0), containing 2 mM ethylenediaminetetraacetate and 0.05% beta-thiodiglycol as eluent allowed the separation of glucose, diketogulonic acid + diketogluconic acid, dehydroisoascorbic acid, dehydroascorbic acid, ascorbic acid, and isoascorbic acid within 55 min. Ascorbic acid in a urine sample was stabilized by the addition of an equal volume of 5% metaphosphoric acid solution, containing 0.5% of beta-thiodiglycol. Filtration of the mixture through a column of Dowex 50W-X8 (H+) facilitated the determination of ascorbic acid and isoascorbic acid in human urine. Samples could be analyzed every 20 min.

Topics: Ascorbic Acid; Benzamidines; Chromatography, High Pressure Liquid; Humans; Spectrometry, Fluorescence

The effects of treatment with calcium L-ascorbate, L-ascorbic dipalmitate, L-ascorbic stearate and erythorbic acid on two-stage urinary bladder carcinogenesis in F344 rats after initiation with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) were examined. Carcinogen was administered at a dose of 0.05% in drinking water for 4 weeks and thereafter the test chemicals were given as a 5% supplement in the diet for the following 32 weeks. No increase in the induction of preneoplastic lesions, papillomas or carcinomas was apparent and it was concluded that none of the test chemicals possess promoting activity for urinary bladder carcinogenesis.

Topics: Animals; Ascorbic Acid; Cocarcinogenesis; Male; Palmitates; Palmitic Acids; Rats; Rats, Inbred F344; Urinary Bladder Neoplasms

Topics: Ascorbic Acid; Diazonium Compounds; Drug Stability; Indicators and Reagents; Nitrites; Spectrophotometry, Ultraviolet

We describe a "high-performance" liquid-chromatographic method for separating and quantifying ascorbic acid (AA) and dehydroascorbic acid (DHA) in plasma and urine. We used a reversed-phase C18 column with an ion-pair reagent and detected the analytes by post-column reaction with 4,5-dimethyl-o-phenylenediamine to form a fluorescent derivative (measured at excitation and emission wavelengths of 365 and 440 nm, respectively). Isoascorbic acid (IA) is the internal standard. Retention times for DHA, AA, and IA are 5.6, 15.5, and 19.9 min, respectively. Between-day CVs for AA in plasma in concentrations of 8 and 20 mg/L were 9% and 7%, respectively. The limit of detection is 10 and 4 ng for AA and DHA, respectively. Results by the present method and the methoxyaniline colorimetric method for AA are comparably accurate.

Topics: Ascorbic Acid; Chromatography, Liquid; Colorimetry; Dehydroascorbic Acid; Humans; Reference Standards; Spectrometry, Fluorescence

The erythorbic acid (ErA) content in the tissues of guinea pigs administered ErA was compared with that of ascorbic acid (AsA). Guinea pigs were administered 1, 5, 20, and 100 mg ErA/day or 1, 5, and 100 mg AsA/day for 16 days and then sacrificed. The liver, adrenal glands, spleen, and kidneys were removed to determine the contents of ErA and AsA using HPLC. Only a small amount of ErA was found in four tissues of the animals administered 20 mg or more of ErA/day. On the contrary, AsA was found in the tissues of all animals administered 1 mg or more of AsA/day. The ErA content in the tissues was much lower than that of AsA even when the amount of ErA administered was the same as that of AsA. However, the body weight gains of animals administered ErA were similar to those of animals administered AsA. These observations suggested that the mechanism of the retention of ErA in the tissues was much different from that of AsA and that the vitamin C activity of ErA might be more than one-twentieth that of AsA.

Topics: Adrenal Glands; Animals; Ascorbic Acid; Body Weight; Chromatography, High Pressure Liquid; Diet; Dose-Response Relationship, Drug; Guinea Pigs; Kidney; Liver; Male; Spleen; Stereoisomerism; Time Factors

Topics: Animals; Ascorbic Acid; Caffeine; Calcium; Dose-Response Relationship, Drug; Female; Injections, Intraventricular; Male; Rabbits

The effect of D-isoascorbic acid, an epimer of L-ascorbic acid, on viruses was investigated using a wide variety of bacterial viruses (phages) as model systems. D-isoascorbic acid exerted an inactivating effect on all phages examined. The reaction mechanism of virus inactivation by D-isoascorbic acid was investigated using phage J1 as a model system. Bubbling oxygen through the reaction mixture and the addition of H2O2 or transition metal ions into the reaction mixture enhanced the phage inactivation by D-isoascorbic acid. In contrast, nitrogen bubbling and the addition of reducing agents, chelating agents or radical scavengers prevented phage inactivation. Experiments using specific radical scavengers, superoxide dismutase or catalase showed that OH. could be mainly responsible for phage inactivation by D-isoascorbic acid. These findings are similar to those obtained with L-ascorbic acid, and indicate that phage-inactivating activity is independent of the stereoisomerism with inversion of the hydroxyl group at carbon 5 of ascorbic acids.

Topics: Ascorbic Acid; Bacteriophages; Catalase; Edetic Acid; Free Radicals; Hydroxides; Hydroxyl Radical; Metals; Oxidation-Reduction; Oxygen; Superoxide Dismutase

Topics: 2,3-Diketogulonic Acid; Ascorbic Acid; Chromatography, High Pressure Liquid; Dehydroascorbic Acid; Gluconates; Indicators and Reagents; Spectrophotometry, Ultraviolet; Stereoisomerism; Sugar Acids

The effect of erythorbic acid (ErA) on ascorbic acid (AsA) content in the tissues of normal and AsA-deficient guinea pigs was studied. The animals were sacrificed at varying intervals during the experimental period, and the liver, adrenal glands, spleen and kidneys were removed. The amounts of AsA and ErA in the tissues were measured by HPLC. The content of AsA in the tissues of the animals administered both AsA and ErA was lower than that of the animals administered only AsA. But the disappearance rate of AsA from the tissues of the AsA-deficient animals was similar to that of the animals administered only ErA. The amount of AsA in the tissues of the animals administered both AsA and ErA during the repletion period was lower than that of the animals administered only AsA. These results suggest that ErA administration may affect the amount of AsA in the tissues by inhibiting its tissue uptake or its storage in the tissues, and not by accerelating the catabolism of AsA in the tissues.

Topics: Adrenal Glands; Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Biological Availability; Body Weight; Chromatography, High Pressure Liquid; Guinea Pigs; Kidney; Liver; Male; Spleen

Ascorbic acid (AsA), added to nutrient broth at a concentration of 5 mmol/l, was bactericidal towards Campylobacter jejuni grown at 42 degrees C in a micro-aerobic atmosphere. Specific enzymes, radical scavengers, metal chelators and reducing agents were tested as possible antagonists to the cytotoxicity of AsA. The addition of catalase or of the metal chelators ceruloplasmin or Desferal did not prevent the cytotoxic effect of AsA. The addition of the hydroxyl radical scavengers mannitol, formate, histidine or DMSO also failed to counteract the toxicity of AsA. On the other hand, thiourea or cysteamine and the reducing agents cysteine or dithionite significantly increased the recovery of C. jejuni in the presence of AsA. Although the possibility of the involvement of hydroxyl radicals in AsA cytotoxicity cannot be ruled out, it appears that the toxic effect of AsA is due mostly to the formation of products of oxidation of AsA and particularly to dehydroascorbic acid (DHA). Dehydroascorbic acid was also bactericidal to C. jejuni at a concentration of 5 mmol/l. Of all the compounds tested, only cysteamine was effective in preventing (partially) the toxic effect of DHA. The growth of C. jejuni was not inhibited by the addition of 5 mmol/l of isoascorbic acid or sodium isoascorbate.

Topics: Ascorbic Acid; Campylobacter fetus; Dehydroascorbic Acid; Humans

The effect of graded doses of erythorbic acid (ErA) on the content of ascorbic acid (AsA) in the tissues of guinea pigs administered AsA was studied. The guinea pigs were administered 5 mg AsA and 1, 5, 20, and 100 mg ErA; or 1 mg AsA and 1 and 20 mg ErA; or 20 mg AsA and 20 mg ErA for 16 days. The animals were then sacrificed, and the liver, adrenal glands, spleen, and kidneys were removed to determine the contents of AsA and ErA by using HPLC. The content of AsA in the tissues of the animals administered less than 5 mg ErA together with 5 mg AsA was not significantly different from that of the animals administered 5 mg AsA. The administration of 100 mg ErA together with 5 mg AsA caused a decrease in the amount of AsA in the tissues. The content of AsA in the tissues of the animals administered ErA together with 1 mg AsA was not significantly different from that of the animals administered 1 mg AsA. In the case of animals administered an equal amount of both AsA and ErA, the AsA tissue content was consistently much higher than that of ErA. These results indicated that the administration of relatively small amounts of ErA did not appear to reduce the availability of AsA.

Topics: Adrenal Glands; Animals; Ascorbic Acid; Biological Availability; Dose-Response Relationship, Drug; Guinea Pigs; Kidney; Liver; Male; Spleen

The modifying effects of 3 antioxidants, sodium L-ascorbate (SA), ascorbic acid (AA) and sodium erythorbate (SE) on two-stage gastric carcinogenesis in F344 rats initiated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were investigated. Administration of 5% SE in the diet significantly decreased the incidence of dysplasia of the pylorus and, more marginally the incidence of papilloma of the forestomach, whereas administration of 5% and 1% SA and 5% AA in the diet was not associated with effect. These results suggest that SE exerts a weak inhibitory effect on gastric carcinogenesis.

Topics: Animals; Ascorbic Acid; Body Weight; Cocarcinogenesis; Male; Methylnitronitrosoguanidine; Rats; Rats, Inbred F344; Stomach Neoplasms; Urinary Bladder Neoplasms

The four O-H bands of ascorbic acid could be assigned by means of infrared investigations. It could be shown by electron spin resonance and nuclear magnetic resonance measurements that the radical sodium ascorbate is formed by a cyclic side-chain structure resulting in a loss of C(6)-OH and C(3)-OH. The C(2) = C(3) double bond is still maintained as could be shown by infrared and ultraviolet absorption spectroscopy. In the case of complete oxidation of ascorbic acid to dehydroascorbic acid, C(6)-OH is reestablished (indicating the reopening of the furanoid ring), while C(2)-OH as well as the C(2) = C(3) double bond have disappeared due to the deprotonation of C(2)-OH and C(3)-OH. In the case of isoascorbic acid and its radical potassium isoascorbate similar results are obtained with one distinct difference: in the case of isoascorbic acid, C(2)-OH does not appear while C(3)-OH exhibits a shoulder.

Topics: Ascorbic Acid; Chemical Phenomena; Chemistry; Electron Spin Resonance Spectroscopy; Magnetic Resonance Spectroscopy; Molecular Conformation; Spectrophotometry, Infrared; Spectrophotometry, Ultraviolet; Structure-Activity Relationship

ESR investigations on lyophilized systems have shown that the signal at g = 2.005 can be explained by an interaction between Na+ or K+ and the anionic ascorbyl radical. The unpaired electron is probably localized near the C(4) region and is produced by a cleavage of an H atom belonging to a water molecule bound tightly to C(4). Experiments on aqueous samples revealed that ascorbic acid in its radical configuration and in its highest concentration exists only at physiological pH and temperature. An additional splitting is obtained by the ring formation between C(3) and C(6)-OH. The coupling constants of the triplets produced by the CH2-6 protons differ between ascorbic acid and isoascorbic acid. Thus, the ESR technique can be applied for an easy distinction between these two epimers.

Topics: Ascorbic Acid; Chemical Phenomena; Chemistry; Dehydroascorbic Acid; Electron Spin Resonance Spectroscopy; Erythrocytes; Free Radicals; Humans; Leukemia, Lymphoid

Carcinogenicity of sodium erythorbate, a widely used antioxidant food additive, was evaluated using a total of 306 eight-week-old male and female F344/DuCrj rats. Test rats were given 1.25 or 2.5% aqueous solution as drinking water for 104 weeks. Controls were given tap water. All the rats were fed commercial pellets. None of the tumors observed was attributable to sodium erythorbate in drinking water. Neither concentration of sodium erythorbate changed the pattern of spontaneous tumor development in both sexes, except for a slight reduction in aggregate tumor incidence in the 2.5% Group females. Additionally, 2.5% solution suppressed body weight gains in both males and females. These results and prior data by others together suggest that weak mutagens may be noncarcinogenic under certain conditions.

Topics: Aging; Animals; Antioxidants; Ascorbic Acid; Body Weight; Female; Food Additives; Male; Neoplasms; Rats; Rats, Inbred F344

Ascorbic acid, isoascorbic acid and dehydroascorbic acid inhibit bovine kidney alkaline phosphatase activity. Ascorbic acid free radicals seem not to be involved. Dialysis does not make the inactivation reversible. A competitive mechanism can be inferred from experiments with phosphate and substrates, which block the activity decay. The influence of temperature, pH, other inhibitors and tertiary structure modifications on the inactivation process is also investigated.

Topics: Alkaline Phosphatase; Animals; Ascorbic Acid; Binding, Competitive; Cattle; Dehydroascorbic Acid; Hydrogen-Ion Concentration; Kidney; Structure-Activity Relationship; Temperature

Ascorbic acid/isoascorbic acid are present as radicals at physiological pH with the unpaired electron located in the C(4) region. Since a distinction can be made between both types of radicals, the electron spin resonance technique can be used for discrimination between the epimers of vitamin C. The radical has a cyclic side-chain structure which is formed by the hydrogen bond C(3)-O-... HO-C(6) (approximately equal to 2.7 kJ) and which engulfs Na+ or K+ in the case of the ascorbyl or the isoascorbyl radical, respectively. The radicals Na-ASC and K-Iso-ASC are electroneutral. Red. glutathione affects both types of radicals by restoring the original electronic configuration at C(4) without changing the electroneutral bicyclic structure. In this way, the mobile carriers Na-ASC and K-Iso-ASC can transport Na+ and K+ across membranes. Its highest efficiency is around 37 degrees C and pH approximately equal to 7, that is, at physiological values. The biological importance of the side chain of vitamin C is outlined and a possible transport mechanism proposed.

Topics: Ascorbic Acid; Biological Transport; Chemical Phenomena; Chemistry; Potassium; Sodium

The promoting effects of ascorbic acid, sodium erythorbate and ethoxyquin on two-stage urinary bladder carcinogenesis in F344 rats initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) at a dose of 0.05% in the drinking water were examined. Administration of 5% sodium erythorbate in the diet significantly increased the incidences of preneoplastic lesions, papilloma and cancer of the urinary bladder, whereas administration of 5% ascorbic acid in the diet did not. Administration of 0.8% ethoxyquin also increased the incidence of neoplastic lesions. Administrations of 5% sodium L-ascorbate and 5% sodium erythorbate caused increases in the pH, the sodium content and crystals of MgNH4PO4 in the urine. These results show that sodium erythorbate and ethoxyquin promote urinary bladder carcinogenesis, while ascorbic acid does not.

Topics: Animals; Ascorbic Acid; Body Weight; Butylhydroxybutylnitrosamine; Carcinogens; Cocarcinogenesis; Electrolytes; Ethoxyquin; Hydrogen-Ion Concentration; Hyperplasia; Male; Nitrosamines; Organ Size; Osmolar Concentration; Papilloma; Quinolines; Rats; Urinary Bladder; Urinary Bladder Neoplasms

Large quantities of ascorbic acid or erythorbic acid were administered to Swiss mice over a period of seven months. Urinary ascorbic acid and erythorbic acid were determined two weeks before termination of the experiment. At the end of the experiment, ascorbic acid and erythorbic acid contents in plasma, liver and brain tissues were measured. In the ascorbic acid-treated mice, there was a marked elevation in plasma and urine ascorbate levels, and there was a 38% increase of ascorbate level in the liver but there was no substantial increase in ascorbate levels in the four brain regions studied, namely the cerebrum, cerebellum, medulla and brain stem, upon large intake of ascorbic acid. In the erythorbic acid-treated mice, erythorbic acid is well absorbed by the gastrointestinal tract, enters the blood stream, and is rapidly excreted in the urine. The results show that erythorbic acid is able to replace 45% of ascorbic acid in the liver and 28-39% of ascorbic acid in the brain tissues. Although erythorbic acid appears in the blood at significantly high level, it does not lower blood ascorbate levels.

Topics: Animals; Ascorbic Acid; Creatinine; Female; Mice

The organ-specific modulation by ascorbic acid and related compounds on alkaline phosphatase activity of calf intestinal and human placental tissues has been studied at pH 8.0 and 37 degrees C. L(+)-ascorbic acid and its isomer D(-)-ascorbic acid inhibit to a similar extent the intestinal isoenzyme and appear to be more potent modifiers than dehydro-L-(+)-ascorbic acid. In contrast, the placental isoenzyme shows an initial activation by the three chemical agents, followed by an inhibition. The inhibition is lower with L(+)-ascorbic acid and D(-)-ascorbic acid, while its catalytic activity is affected only slightly by dehydro-L-(+)ascorbic acid.

Topics: Alkaline Phosphatase; Animals; Ascorbic Acid; Cattle; Dehydroascorbic Acid; Female; Humans; Intestines; Isoenzymes; Placenta; Pregnancy; Stereoisomerism; Time Factors

Topics: Adenocarcinoma; Animals; Antioxidants; Ascorbic Acid; Carcinoma, Squamous Cell; Male; Methylnitronitrosoguanidine; Neoplasms; Rats; Rats, Inbred F344; Sarcoma; Stomach Neoplasms

Topics: Animals; Ascorbic Acid; Brain Chemistry; Chromatography, High Pressure Liquid; Electrochemistry; Food Analysis; Liver; Mice

Administration of ascorbic acid at moderate doses/0.05-0.1 g per kg of body mass/was shown to induce tyrosine transaminase in liver tissue of intact rats. The enzyme induction depended on the state of adrenal glands and was inhibited by actinomycin D. As distinct from the native form of L-ascorbic acid moderate doses of D-isoascorbic acid did not induce the enzyme in rat liver tissue; these data suggest the relative biological inactivity of D-isoascorbic acid.

Topics: Adrenal Glands; Adrenalectomy; Animals; Ascorbic Acid; Dactinomycin; Enzyme Induction; Hydrocortisone; Liver; Male; Rats; Rats, Inbred Strains; Tyrosine Transaminase

Topics: Ascorbic Acid; Collagen; History, 18th Century; History, Ancient; Humans; Hydroxyproline; Procollagen-Proline Dioxygenase; Scurvy

Topics: Ascorbic Acid; Carotenoids; Chemical Phenomena; Chemistry; Free Radicals; Kinetics; Oxygen; Photolysis; Vitamin A

Topics: Animals; Ascorbic Acid; Azides; Biological Transport; Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; Cell Membrane; Kidney Cortex; Kinetics; Microvilli; Rats; Sodium; Valinomycin

High-performance liquid chromatography (HPLC) was applied to the determination of ascorbic acid (AsA) and erythorbic acid (ErA). The apparatus was a Shimadzu model LC-2P Liquid Chromatograph equipped with a UV detector set at 254 nm. The separation was achieved on a LiChrosorb-NH2 column which was pre-treated with 0.1 M ammonium monophosphate solution using a mixture of acetonitrile, acetic acid and water (87:2:11, v/v) as an eluant. The HPLC method has the following advantages: AsA and ErA are quantitated after being distinctly separated, analysis time per one sample is short, and AsA or ErA levels as low as 1.0 X 10(-2) microgram are detectable. Recovery experiments with dehydro-AsA and dehydro-ErA, involving reduction with H2S, give satisfactory results.

Topics: Antioxidants; Ascorbic Acid; Chromatography, High Pressure Liquid; Colorimetry; Stereoisomerism

A method for the separation and determination of ascorbic acid (AsA) and erythorbic acid (ErA) in animal tissues is described. It employs high-performance liquid chromatography on a LiChrosorb-NH2 column in conjunction with a mixture of acetonitrile, acetic acid and water as an eluant. Application of the method, which is sensitive, rapid and simple, to the analyses of AsA and ErA in animal tissues such as liver, adrenals, spleen, kidneys and heart gave satisfactory results. Dehydro-AsA and dehydro-ErA in rat liver could be determined after reduction with H2S. The method was shown to be useful for the routine analyses.

Topics: Adrenal Glands; Animals; Antioxidants; Ascorbic Acid; Chromatography, High Pressure Liquid; Colorimetry; Kidney; Liver; Male; Myocardium; Rats; Rats, Inbred Strains; Spleen; Stereoisomerism

Topics: 2,3-Diketogulonic Acid; Ascorbic Acid; Chromatography, High Pressure Liquid; Dehydroascorbic Acid; Gluconates; Indicators and Reagents; Spectrophotometry, Ultraviolet; Stereoisomerism; Sugar Acids

Female guinea pigs were fed a scorbutigenic diet supplemented with either L-ascorbic acid or D-isoascorbic acid or combinations of these. Their responses were judged by changes in body weight, serum alkaline phosphatase levels, wound healing, and tooth structure. Large additions (100 mg daily) of D-isoascorbic acid to the scorbutigenic diet resulted in normal growth over a 7-wk period and normal serum alkaline phosphatase levels, tooth structure development, and collagen formation after wounding. The addition of 0.5 or 5.0 mg of L-ascorbic acid to this high D-isoascorbic diet improved neither growth rate nor collagen deposition during wound healing. On the basis of changes in tooth structure, D-isoascorbic acid has 1/20 the potency of L-ascorbic acid. Its effect is additive to subminimal maintenance levels of L-ascorbic acid implying that there is no competitive inhibition in the utilization of the two compounds. The relatively weak activity of D-isoascorbic acid is probably due to poor transport to the tissues and ineffective binding to functional sites. This explains why the onset of scurvy is much more rapid after withdrawal of D-isoascorbic acid from the diet when it had been the sole antiscorbutic dietary constituent. It is concluded that D-isoascorbic acid is a "weakly" antiscorbutic agent on the basis that it is both poorly absorbed and retained by the tissue; that in fact it may, to the degree that it is taken up by the tissues and retained, be equal in antiscorbutic potency to L-ascorbic acid.

Topics: Alkaline Phosphatase; Animals; Ascorbic Acid; Dose-Response Relationship, Drug; Female; Growth; Guinea Pigs; Incisor; Scurvy; Stereoisomerism; Structure-Activity Relationship; Wound Healing

Topics: Animals; Antipyrine; Ascorbic Acid; Body Temperature; Drug Interactions; Food Additives; Haplorhini; Ketamine; Macaca fascicularis; Male; Pharmaceutical Preparations; Sleep; Stereoisomerism; Theophylline; Time Factors

Large peroral doses of D-isoascorbic acid, a vitamin C stereoisomer (50 mg per animal per day), were retained in the guinea-pig organism to a smaller extent than the same doses of L-ascorbic acid (vitamin C). Simultaneous administration of the flavonoids rutin and epicatechin increased the amount of D-isoascorbic acid retained in the liver, brain and wall of the small intestine by up to 100%, but four weeks after its extraction from the food the amount of L-ascorbic acid left in the guinea-pig organism still exceeded D-isoascorbic acid reserves. This difference, which was found in all the organs studied, was the largest in the groups simultaneously given flavonoids. In guinea-pigs which, like man, are dependent on an exogenous vitamin C supply, D-isoascorbic acid was metabolized at a manifestly higher rate than L-ascorbic acid, irrespective of whether flavonoids were administered or not. In liver, brain and small intestine wall homogenates, the oxidized forms of both stereoisomers were reduced in the presence of reduced glutathione, but the reduction rate of D-isodehydroascorbic acid was higher and it was stimulated by the two flavonoids more strongly than the reduction of L-dehydroascorbic acid. The stuterospecific.

Topics: Adrenal Glands; Animals; Ascorbic Acid; Brain; Catechin; Dehydroascorbic Acid; Female; Flavonoids; Guinea Pigs; Intestine, Small; Liver; Male; Rutin; Spleen; Stereoisomerism

Low concentration (0.1--1 mM) of ascorbate and erythorbate (isoascorbate) caused lipid peroxidation and lysosome labilization ("cofactor" action). In addition, they acted additively on microsomal NADPH oxidase-induced lipid peroxidation at the low concentration. The "cofactor" action, however, was dependent reciprocally on the density of lysosomes; the more dilute was the lysosomal fraction, the more susceptible the lysosomes were. On the other hand, ascorbate and erythorbate at concentration more than 1 mM inhibited microsomal NADPH oxidase-induced lipid peroxidation and lysosome labilization. Their antioxidant effect was revealed to be clear especially when the "cofactor" action was eliminated by such a basic protein as protamine. Considering that the "cofactor" action was observed only at the lower density of lysosomes and might be inhibited by physiologically occurring basic proteins, ascorbate and erythorbate may mostly act as antioxidant on lysosomes in vivo. Ascorbate- or erythorbate- induced lysosome labilization was certified to be mediated by lipid peroxidation.

Topics: Animals; Antioxidants; Ascorbic Acid; Lipid Peroxides; Liver; Lysosomes; Male; Oxidation-Reduction; Rats; Stereoisomerism

Topics: Ascorbate Oxidase; Ascorbic Acid; Chemical Phenomena; Chemistry; Chemistry Techniques, Analytical; Oxidoreductases; Research

Topics: Ascorbic Acid; Ascorbic Acid Deficiency; Blood Chemical Analysis; Humans; Leukocytes; Metabolism; Urine

Topics: Ascorbic Acid; Chromatography, Paper

Topics: Ascorbic Acid; Carbohydrate Metabolism; Humans

Topics: Ascorbic Acid; Research; Vitamins

Topics: Ascorbic Acid; Penicillium; Vitamins

Topics: Ascorbic Acid; Ascorbic Acid Deficiency; Body Fluids; Humans; Scurvy; Urine; Vitamins

Topics: Ascorbic Acid; Carbohydrate Metabolism; Sucrose; Vitamins

Topics: Ascorbic Acid; Biological Products; Humans; Vitamins

Topics: Ascorbic Acid; Vitamins

Topics: Amides; Ascorbic Acid; Niacin; Nicotinic Acids

Topics: Animals; Ascorbic Acid; Cobalt; Heptoses; Polycythemia; Rabbits; Rats

Topics: Acids; Ascorbic Acid; Immunologic Tests; Quinine; Research Design; Tissues