Levels Of L-ascorbic Acid Research Articles

Ascorbic acid availability from ascorbyl 2-polyphosphate and ascorbyl 2-sulfate in sea bass ( Dicentrarchus labrax)

A trial with a total of 24 European sea bass (mean weight 337±75 g) was conducted to investigate the biological effects of two vitamin C sources, ascorbyl 2-polyphosphate (AP) and ascorbyl 2-sulfate (AS). The fish were held in fiberglass tanks at a density of four fish per tank in synthetic seawater with 17‰ salinity, a temperature of 20°C and 8.2–11.2 mg l −1 dissolved oxygen. The sea bass were fed a vitamin C-free diet for 20 days before and 21 days after oral administration of the two sources of vitamin C as pills (2 pills, each containing 10 mg vitamin C). The placebo and two sources of vitamin C were assigned randomly to the tanks and administered by force feeding. To determine plasma ascorbic acid levels, a pre-experimental blood sample was taken 48 h before oral administration, then 5 h after forced feeding the vitamin C sources and on day 1, 2, 6, 8, 14 and 21 of the post-application period. At 48 h before forced feeding, a plasma l-ascorbic acid value of 3.1 mg l −1 was found. The highest concentration of plasma l-ascorbic acid for both sources of vitamin C was observed 5 h after force feeding (AP 20.7 mg l −1, AS 8.3 mg l −1). On day 1, the level of plasma l-ascorbic acid started to decrease until the end of the experiment at day 21. The average plasma l-ascorbic acid level of fish fed AP was significantly higher than the value of fish fed ascorbyl 2-sulfate and the placebo. These results indicate that l-ascorbic acid is more rapidly adsorbed when administered as ascorbyl 2-polyphosphate and has a higher bioavailability than ascorbyl 2-sulfate in European sea bass.

Different Oxidant Addition and the Effects of Mechanical Dough Methods on the Quality of Bread

In this research, by using different mixer rotation and adding different levels of L-Ascorbicacid and potassiumbromate (KBrO3) to wheat, bread was made by short time bread making methods and the results obtained were evaluated statistically. Spesific volume in bread made by speed mixer (1500 rpm) increased considerably. Staling in bread without fermantation (0 min. main fermantation time) was faster than other treatments. The best colour intensity inside the bread was obtained from the samples in mixer speed of 1500 rpm and 75 ppm L.A.Acid. The highest specific volume and the lowest firmness of bread were obtained from the samples in 30 min. of main fermantation, and the best colour intensity inside bread from the samples in 15 min. of main fermantation. Oxidant level had an increasing effect on specific volume and improved bread porosity. Using high speed mixers and oxidants appeared positive results as to mechanically dough naturation and bread property.

Cellular antioxidant defense by a ubiquinol-regenerating system coupled with cytosolic NADPH-dependent ubiquinone reductase: protective effect against carbon tetrachloride-induced hepatotoxicity in the rat.

We found that NADPH-dependent ubiquinone reductase (NADPH-UQ reductase) in rat liver cytosol reduces ubiquinone (UQ) to ubiquinol (UQH2) in lipid membranes and consequently inhibits lipid peroxidation [Takahashi T., et al., Biochem. J., 309, 883-890 (1995)]. Here we examined whether or not this UQH2-regenerating system functions as a cellular antioxidant defense in animals. Rats were given UQ-10 for 2 weeks, and were then exposed to carbon tetrachloride (CCl4). The UQ-10 supplement increased only in the NADPH-UQ reductase and the UQH2-10 pool of rat liver without any appreciable change in the levels of other antioxidant factors. On the other hand, CCl4 markedly increased plasma aspartate aminotransferase and alanine aminotransferase, liver weight and thiobarbituric acid reacting substances formation, which are indicators of CCl4-hepatitis, and it decreased the liver levels of L-ascorbic acid, reduced form of glutathione (GSH), alpha-tocopherol, NADPH-UQ reductase and glutathione S-transferase. However, all the above indicators of CCl4-induced hepatitis were significantly improved in rats given UQ-10. Furthermore, alpha-tocopherol, but neither L-ascorbic acid nor GSH, was significantly saved. UQ-10 supplement also was recovered glutathione S-transferase and NADPH-UQ reductase activities slightly. These results indicated that UQ-10 given to rats increased the cellular UQH2-10 pool and cytosolic NADPH-UQ reductase activity in their livers, resulting in the inhibition of lipid peroxidation in the biomembranes, and consequently protected the rats from the CCl4-hepatotoxicity.

Effect of vanadium on l-ascorbic acid concentration in rat tissues

1. 1. Two-month old Wistar rats of both sexes received, as sole drinking liquid, an aqueous solution of ammonium metavanadate (AMV) at a concentration of 0.01, 0.05, 0.15 and 0.30 mg V/ml (corresponding to 0.2, 1, 3 and 6 mM solution) over 4 weeks. 2. 2. In the animal groups receiving AMV solution of 0.15 or 0.30 mg V/ml concentrations to drink, a statistically significant decrease of the uptake of food and AMV solution was observed, as compared with food and water taken up in the same time by the control group. 3. 3. Moreover, a distinct decrease of the l-ascorbic acid level was noted in the liver, kidneys, spleen and adrenals. These differences proved statistically significant in single cases of animals receiving a solution of 0.05 and 0.15 mg V/ml concentration and in all animals given the solution at the highest vanadium concentration.

Effect of chronic vanadium administration in drinking water to rats.

Two-month old Wistar rats of both sexes received, as sole drinking liquid, an aqueous solution of ammonium metavanadate (AMV) at a concentration of 0.01 or 0.05 mg V cm-3 (0.2 or 1.0 mM) for a period of 4 weeks. It was calculated that the animals took up doses of 1.5 and 5-6 mg V kg body weight-1 24 h-1, respectively. Food and AMV solution consumption in the experimental group was similar to food and water consumption in the control group. A statistically significant decrease of consumption of AMV solution at a concentration of 0.05 mg V cm-3 was noted only in males. Hematological examination demonstrated a decrease in the erythrocyte count, hemoglobin level and hematocrit index. This decrease in the erythrocyte count was associated with an increased percentage of reticulocytes in the peripheral blood of the animals drinking the solution with a higher vanadium content. Biochemical analyses demonstrated a decrease of L-ascorbic acid levels in the plasma and erythrocytes of animals drinking the AMV solutions. A distinct tendency for the malonyldialdehyde level to increase in the blood was also observed. Among the enzymes examined in the erythrocytes (catalase, glucose-6-phosphate dehydrogenase, lactate dehydrogenase and delta-aminolevulinic acid dehydratase [ALA-D]) only ALA-D activity was depressed.

Dietary rutin has limited synergistic effects on vitamin C nutrition of fingerling channel catfish (Ictalurus punctatus)

A study was conducted to determine the possible synergistic effects between dietary rutin (a bioflavonoid) and vitamin C, and to evaluate their antioxidant effects in fingerling channel catfish. Purified casein/gelatin diets containing two levels of rutin (0 and 1000 mg/kg diet) and three levels of L-ascorbic acid (0, 1500 and 3000 mg/kg diet) in a factorial arrangement were fed to fingerling channel catfish for 16 weeks. Fish fed the diets without supplemental vitamin C showed deformed spinal columns, external hemorrhages and fin erosion after 10 to 12 weeks. Also these fish had significantly (p < 0.05) depressed body weight gain, feed efficiency, hematocrit, hepatosomatic index (% liver weight), as well as reduced liver, fillet and plasma vitamin concentrations after 16 weeks. Liver, fillet and plasma vitamin C concentrations were correlated with dietary vitamin C levels. Forced oxidation of fillet samples significantly (p < 0.05) increased 2-thiobarbituric acid (TBA) values of fillets from fish fed diets without vitamin C and rutin. However, results from the present study indicated only limited synergistic effects of dietary rutin on vitamin C nutrition of channel catfish.

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.

Synergism of ascorbic acid and glutathione in the reduction of hexavalent chromium in vitro.

The reduction of 20 microM hexavalent chromium [chromium(VI)] in single-reductant solutions of 0.02-2 mM L-ascorbic acid (L-AsA) or 2 mM reduced glutathione (GSH), and in mixed solutions of 2 mM GSH containing L-AsA of the above-described concentrations was investigated at physiological pH (37 degrees C). The reduction of chromium(VI) in the L-AsA solutions of higher concentrations showed pseudo-first-order kinetics in a single phase with respect to chromium(VI). In the lower L-AsA concentrations, pseudo-first-order processes appeared only in an early stage of the reaction. The reduction in the GSH solution was characterized by a two-phase process. In the first phase, which appeared in very short duration, the reaction rate was much higher than that in the second, but resulted in a decrease of only 7% of the initial chromium(VI) level. The second phase showed the main process of the reduction. This indicated pseudo-first-order kinetics. The half-life values of chromium(VI) depended on the initial levels of the reductants and ranged from seconds to hours. The chromium(VI)-reducing ability of L-AsA was markedly higher than that of GSH. In the mixed solutions of L-AsA and GSH, synergistic effect on the reduction of chromium(VI) was observed, especially in earlier stages of the processes. The synergism was more conspicuous in the mixed solutions containing lower L-AsA levels. These results suggest that although AsA possesses higher reducing ability than GSH, their coexistence is of importance for the reduction of chromium(VI) in biological systems because of their synergism.

Microdetermination of L-ascorbic acid in pharmaceutical preparations by iodide ion-selective electrode and spectrophotometry

Two methods for determining low levels of L-ascorbic acid in pharmaceutical preparations are described. The potentiometric method is based on oxidation of an aqueous ascorbic acid solution with iodine in chloroform. The iodide ions produced in the aqueous phase are determined with the iodide ion-selective electrode using a standard calibration graph technique. The spectrophotometric method is based on oxidation of ascorbic acid with iron(III). The equivalent amount of iron(II) produced is determined as iron(II)-2,4,6-tri(2′-pyridyl)-triazine chelate at 595 nm. The results show a mean recovery of 100.067±0.1435 for the potentiometric method, 100.267±0.32 for the spectrophotometric method.

The antiscorbutic action of l-ascorbic acid and d-isoascorbic acid (erythorbic acid) in the guinea pig

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.

Use of L-Ascorbic Acid, Ethocel Coated Ascorbic Acid and Ascorbate 2-Sulfate in Diets for Channel Catfish, Ictalurus punctatus

Purified diets with five levels (25, 50, 75, 100, and 200 mg/kg) of supplemental L-ascorbic acid (LAA), and equimolar levels of ethylcellulose coated L-ascorbic acid (EAA) and dipotassium L-ascorbate 2-sulfate dihydrate (AS) were pelleted and fed to 7.9 +/- 0.2 g channel catfish fingerlings for 20 weeks. A dietary level of 23 mg/kg of all three forms of vitamin C prevented spinal abnormalities. Approximately 50 mg/kg diet of either LAA or EAA was sufficient for maximal growth and feed efficiency. Growth response to AS was similar to a Michaelis-Menten type curve and 200 mg/kg diet of AS was necessary to achieve maximal growth. Blood and liver ascorbic acid levels were positively correlated with supplemental levels of LAA, EAA, and AS up to 200 mg/kg; however, blood and liver ascorbic acid levels of fish fed AS were considerably less than those fed LAA and EAA. Weight gains were positively correlated with blood ascorbate levels up to 7 microgram/ml. No measurable level of AS was detected in blood or liver. These results suggest that the rate of enzymatic hydrolysis of AS to LAA or rapid excretion of AS may have been the limiting factor.

Ascorbic acid and l-gulonolactone oxidase in lagomorphs

1. 1. The activity of l-gulonolactone oxidase (EC 1.1.3.8) in the liver of eastern cottontail rabbits ( Sylvilagus floridanus) is about 10-fold greater in winter than in summer. 2. 2. l-gulonolactone oxidase activity is low and tissue ascorbate high during all seasons in snowshoe hares ( Lepus americanus). 3. 3. Liver contents of ascorbate fall to low levels in L. americanus fed on rabbit chow in the laboratory. 4. 4. The activity of l-gulonolactone oxidase in liver of Sylvilagus and Oryctolagus is depressed by feeding high levels of l-ascorbic acid. 5. 5. The New Zealand White breed of domestic rabbit ( Oryctolagus cuniculus) has considerably higher levels of l-gulonolactone oxidase and liver ascorbate than does the Dutch breed. 6. 6. In a wild population of Oryctolagus sampled in Australia l-gulonolactone oxidase levels were intermediate between those of the two domestic breeds and more variable than either.

Determination of L-ascorbic acid levels in culture medium: concentrations in commercial media and maintenance of levels under conditions of organ culture.

The method of Deutsch and Weeks was modified to provide a reliable and reasonably quick method for assaying the L-ascorbic acid content of culture medium. The modified method was used to determine the decay of L-ascorbic acid under various conditions of culture and the concentration of the vitamin in commercially prepared media. The half-life of L-ascorbic acid in a modified New circulator gassed with 95% O2 + 5% CO2 was 1.5 hr.; and when gassed with 20% O2 + 5% CO2 + 75% N2, about 2 hr. In Petri dishes gassed with 20% O2 + 5% CO2 + 75% N2, the half-life of L-ascorbic acid was 0.9 hr. About 4% of the L-ascorbic acid was lost per day when medium was stored at 0 degrees C and about 9% per day when stored at 5 degrees C. When medium with an initial content of 300 microng per ml was stored at room temperature, the half-life was found to be 15.5 hr. The L-ascorbic acid in five commercially available media, which contain the vitamin in their formulations, was assayed immediately after their delivery to the laboratory. The values of L-ascorbic acid measured in these media were in all cases far lower than prescribed. A continuous-flow organ culture system has been designed which allows the provision of a relatively constant level of L-ascorbic acid to explant by taking advantage of the slow oxidation of L-ascorbic acid at 0 degrees C.

EFFECT OF PCB (POLYCHLOROBIPHENYLS) ON L-ASCORBIC ACID, PYRIDOXAL PHOSPHATE AND RIBOFLAVIN CONTENTS IN VARIOUS ORGANS AND ON HEPATIC METABOLISM OF L-ASCORBIC ACID IN THE RAT

Effects of continuous oral administration of PCB (polychlorobiphenyls, 10-100 mg/kg/day, 4 weeks) on tissue levels of L-ascorbic acid (vitamin C), pyridoxal phosphate and riboflavin (vitamin B2) in various organs and on hepatic metabolism of L-ascorbic acid were examined in male Wistar rats weighing 150-250 g. Riboflavin contents in the liver, kidney, brain, heart and testis were not altered by PCB treatments, whereas the hepatic level of pyridoxal phosphate, a biologically active form of vitamin B6, was significantly reduced by PCB administration. Under the same experimental conditions, L-ascorbic acid contents in the liver, kidney, lung and testis showed a significant increase. Histochemical studied revealed that in the adrenal gland, increase of L-ascorbic acid was localized in the fasciculate and reticular zones of cortex, respectively. It was found that increase of L-ascorbic acid in the liver is caused predominantly by activation of biosynthesis at the steps of galactose to D-glucuronic acid and is not due to changes in the catabolic processes of L-ascorbic acid per se. Possible significance of these changes in tissue levels and/or metabolism of vitamins in the occurrence of PCB intoxication is briefly discussed.

Effect of hydrocortisone on the metabolism of l-ascorbic acid in rats

Adrenalectomy causes a significant decrease in the tissue levels of l-ascorbic acid. The ascorbic acid concentration is raised when adrenalectomized animals receive hydrocortisone. Various enzymes of l-ascorbic acid metabolism have been measured in rats after adrenalectomy and subsequent treatment with hydrocortisone and/or actinomycin D. Hydrocortisone stimulates the activity of liver gulono-oxidase responsible for the synthesis of l-ascorbic acid from l-gulonolactone. A slight increase in the activity of dehydroascorbatase is also observed in the adrenalectomized rats. Little change was observed in uronolactonase, l-gulonate dehydrogenase and l-gulonate decarboxylase activities.

Ascorbic acid malabsorption in thalassaemia

In all groups of thalassaemic children, before loading, the plasma l-ascorbic acid was found invariably lower than in controls. In groups I and II after oral administration of 50 and 100 mg respectively, of ascorbic acid per kg body weight, the plasma l-ascorbic acid level rose significantly less in thalassaemic children than in the controls. Moreover, in group II, after doubling the loading dose (100 mg of ascorbic acid per kg body weight) the increment in plasma l-ascorbic acid level was greater in the controls than in thalassaemic children; also the rate of decrease was delayed in thalassaemic patients up to 6 h. Loading with ascorbic acid intramuscularly (group III), resulted in parallel increase and decrease rates of plasma l-ascorbic acid levels up to the 6th h in the thalassaemic children and in the controls. The above results strongly suggest that in thalassaemia we have to do with ascorbic acid malabsorption.

Динамика витамина С в растениях картоФеля, обработанного этиленхлоргидрином

The levels of l-ascorbic acid, dehydroascorbic acid and of the bound form of vitamin C were investigated in the tissue from the vicinity of eyelets of dormant potatoes after treating the tubers with ethylene chlorhydrin. During the first week after exposure the l-ascorbic acid level does not change, significantly while the dehydroascorbic acid level decreases markedly. This decrease persists even during the following weeks and returns to normal only on the fourth week after treatment. The l-ascorbic acid level displays a decreasing tendency but a marked decrease may be observed only during the fourth experimental week. The level of the bound form of vitamin C does not change significantly for the whole duration of the experiment.