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At least 271 records · Page 15Linked to original sources
PubMed1966

Effect of ascorbic acid on the serum folic acid estimation.

Ascorbic acid added to the basal medium increased the growth response of Lactobacillus casei in folic acid standards. The effect in the serum extracts was not marked, resulting in lowered serum folic acid estimations. However, results obtained on prolonged incubation were similar whether ascorbic acid was added or not. The presence or absence of ascorbic acid and variation of the incubation period may account for differences in reported normal ranges of serum folic acid levels.

Ascorbic Acid↗
PubMed1984

Synthesis of l-(+)-Tartaric Acid from l-Ascorbic Acid via 5-Keto-d-Gluconic Acid in Grapes.

5-Keto-l-idionic acid ( identical with5-keto-d-gluconic acid, d-xylo-5-hexulosonic acid) was found as a metabolic product of l-ascorbic acid in slices of immature grapes, Vitis labrusca L. cv ;Delaware'. Specifically labeled compounds, recognized as metabolic products of l-ascorbic acid in grapes, were fed to young grape tissues to investigate the metabolic pathway from l-ascorbic acid to l-(+)-tartaric acid.Label from dehydro-l-[1-(14)C]ascorbic acid, 2-keto-l-[1-(14)C]idonic acid (l-xylo-2-hexulosonic acid), l-[1-(14)C]idonic acid, or 5-keto-l-[1-(14)C] idonic acid was incorporated into l-(+)-tartaric acid in high yields as it was in the l-[1-(14)C]ascorbic acid experiment. In a double label experiment involving a mixture of l-[1-(14)C]idonic acid and l-[2-(3)H]idonic acid, the (3)H/(14)C ratios of 5-keto-l-idonic acid and l-(+)-tartaric acid synthesized in young grape leaves were almost the same as the value of the l-idonic acid fed. Label from 5-keto-l-[6-(14)C]idonic acid was incorporated into sugars and insoluble residue in the same way as l-[6-(14)C]ascorbic acid was metabolized in grapes.These results provide strong evidence that in grapes l-(+)-tartaric acid is synthesized from the C(4) fragment that corresponds to the C1 to C4 group of the 5-keto-l-idonic acid derived from l-ascorbic acid via 2-keto-l-idonic acid and l-idonic acid.

Journal Article↗
PubMed1984

Simultaneous determination of uric and ascorbic acids in human serum by reversed-phase high-performance liquid chromatography with electrochemical detection.

A rapid, easy, and accurate method for the determination of uric acid and ascorbic acid in human serum by reversed-phase high-performance liquid chromatography with electrochemical detection has been developed. Human serum (0.5 ml) was mixed with 1.5 ml of an aqueous solution containing 2.0% metaphosphoric acid and the mixture was centrifuged at 3000g for 30 min. The supernatant was passed through a membrane filter to remove the particulate matter. Ten microliters of the filtrate was injected into the chromatographic system employed in this study. Complete separation of uric acid and ascorbic acid was achieved in about 2 min. The assay limit for quantitation was about 10 pg for uric acid and ascorbic acid under the present chromatographic conditions. The analytical recoveries of uric acid and ascorbic acid in human serum samples were found to be almost 100%.

Ascorbic Acid↗
PubMed1996

Ascorbic acid 2-O-alpha-glucoside, a stable form of ascorbic acid, rescues human keratinocyte cell line, SCC, from cytotoxicity of ultraviolet light B.

Environmental exposure to ultraviolet light B (UVB, wave lengths 290-320 nm) of the solar spectrum causes major damage, including an inflammatory response, in skin. In the present study, we estimated the ability of a stable derivative of ascorbic acid, ascorbic acid 2-O-alpha-glucoside (AA-2G), to reduce UVB damage, using the human keratinocyte cell line, SCC, established from squamous cell carcinoma. By pre- (9 h) and post-cultivation with AA-2G, a significant preventive effect on the decrease in the absolute number of surviving cells by exposure to UVB (typical dose, 20 mJ/cm2) was measurable by a neutral red-uptake assay. The release of lactate dehydrogenase from the cell membrane damaged by UVB was inhibited by AA-2G. In agarose gel electrophoresis, relatively high molecular weight DNA fragments were detected in irradiated cells after 6 h post-irradiation, suggesting that the mechanism of cell death was necrosis. Quantitative analysis of DNA content by flow cytometry indicated that AA-2G suppressed both an increase in debris with degraded nuclei and a decrease in cells in G1 and S phases, but not in the G2/M phase, by UVB exposure. These data suggest that AA-2G shows a photoprotective effect against UVB-induced damage in human epithelial cells.

Ascorbic Acid↗
PubMed1998

Continuous of "pulse-and-withdraw" supply of ascorbic acid in the diet: a new approach to altering the bioavailability of ascorbic acid, using teleost fish as a scurvy-prone model.

In scurvy-prone animals ascorbic acid uptake is regulated by the number of intestinal "brush-border" carriers available for transport. The number of carriers is negatively affected by an increasing dietary ascorbic acid intake, thus limiting the maximum attainable uptake. We tested a new approach towards manipulating the accumulation of ascorbic acid in rainbow trout by repeatedly feeding a 10 day ascorbic acid allowance in a 1 or 3 day "pulse" followed by withdrawal, rather than spread out over the entire 10 day period. Pulse dosing led to initially increased mortalities compared to continuous dosing, but this was reversed after 55 days. Although individual weight and cumulative mortality were not significantly different after 88 days, total liver ascorbic acid levels were significantly higher in the 1-day pulse group (16.3 +/- 3.9 micrograms/g) than in the 3-day pulse (9.8 +/- 0.9 micrograms/g) or continuous (9.3 +/- 0.9 micrograms/g) groups. This led us to conclude that after an initial adaptation phase a feeding profile with intermittent ascorbic acid withdrawal results in a compensatory increase in uptake of ascorbic acid from the diet and/or a better conservation of the body pool of ascorbic acid, opening interesting new avenues for ascorbic acid dosing and therapy.

Animals↗
PubMed1993

The bioavailability to humans of ascorbic acid from oranges, orange juice and cooked broccoli is similar to that of synthetic ascorbic acid.

The relative bioavailability of ascorbic acid from several sources was compared in 68 male non-smokers. Subjects underwent two 8-wk ascorbic acid depletion-repletion cycles. In repletion, subjects were randomized to receive 108 mg/d ascorbic acid as tablets with or without iron, as orange segments or juice, or as raw or cooked broccoli with a crossover within each major treatment group (e.g., cooked to raw broccoli) for the second repletion. Relative ascorbic acid bioavailability was estimated based on the slope obtained from linear regression of plasma ascorbic acid on time during each repletion. In the first repletion, slopes for all groups were similar except for the group consuming raw broccoli (20% lower response, P < 0.01). Second repletion responses were attenuated, but were similar to the first repletion. Ascorbic acid ingested as cooked broccoli, orange juice or fruit, or in synthetic form seems to be equally bioavailable. The lower relative bioavailability of ascorbic acid from raw broccoli is unlikely to be of practical importance in mixed diets.

Adult↗
PubMed1986

Effects of lipophilic derivatives of L-ascorbic acid and dehydro-L-ascorbic acid on the peroxidation of linoleic acid in neutral phosphate buffer containing alcohol.

6-O-Palmitoyl-AsA (AP) and -DHA (DHAP) suppressed LA peroxidation considerably in both 10% and 20% EtOH solutions. The duration of the suppression of LA peroxidation was longer with AP than with DHAP. But after the initial suppression of LA peroxidation, both derivatives showed an accelerating effect. 6-O-Acetyl-AsA (Ac-AsA) and -DHA (Ac-DHA) accelerated LA peroxidation from the start of the reaction in 10% EtOH, but suppressed it notably in 20% EtOH. 4-Phenyl-2,3-dihydroxy-2-buten-4-olide (PDHB) and 4-phenyl-2,3-dioxo-4-butenolide (PDOB) accelerated LA peroxidation in 10% EtOH. With 20% EtOH solution, PDHB suppressed LA peroxidation notably, as did AP, but PDOB showed only a short duration (about 1 h) of suppression. These results suggest the complexity of LA peroxidation catalyzed by lipophilic AsA or DHA in aqueous solution containing alcohol.

4-Butyrolactone↗
PubMed1991

L-ascorbyl-2-monophosphate has equal antiscorbutic activity as L-ascorbic acid but L-ascorbyl-2-sulfate is inferior to L-ascorbic acid for channel catfish.

Channel catfish (Ictalurus punctatus) fingerlings (13 g average initial weight) were fed semipurified diets supplemented with 0, 0.06, 0.12, 0.24 and 0.72 mmol/kg (0, 11, 22, 44 or 132 mg/kg) of ascorbic acid molar equivalent supplied by either L-ascorbic acid, L-ascorbyl-2-monophosphate (Mg salt) (AAP), or L-ascorbyl-2-sulfate (K salt) (AAS). After 14 wk, weight gains were equal for all fish fed diets containing L-ascorbic acid or AAP; however, growth rates were less for fish fed AAS at all dietary levels and for fish fed the ascorbic acid-free diet (control). There were no gross signs of vitamin C deficiency in any of the fish fed L-ascorbic acid or AAP, whereas spinal deformities were found in the controls and in fish fed all but the highest concentration of AAS. The percentage of spinal deformities decreased as dietary levels of AAS increased. Reduced bone collagen content and histopathology in liver and gill tissues also indicated ascorbic acid deficiency in the controls and in fish fed all but the highest concentration of AAS. Limited histopathology was found in fish fed the lowest level of L-ascorbic acid but not in those fed the lowest level of AAP. Regression analysis of weight gain data showed that the vitamin activity of ascorbic acid from AAS was only 5.2% of that from L-ascorbic acid for growth. This study indicates that AAP has equimolar activity to L-ascorbic acid as a vitamin C source for channel catfish and that AAS has vitamin activity for this species but at a much lower level than the other compounds.

Administration, Oral↗