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PubMed2004

Effects of ascorbic acid on oxidative system and transient evoked otoacoustic emissions in rabbits exposed to noise.

OBJECTIVES/HYPOTHESIS: The objective was to investigate the effects of both noise exposure and ascorbic acid on oxidative status and hearing thresholds of rabbits. STUDY DESIGN: Randomized prospective animal study comparing oxidative parameters and otoacoustic emissions in two rabbit groups exposed to noise. One group was given ascorbic acid, the other group was not given any treatment. METHODS: Two groups of rabbits were used in the study; each group had six rabbits. The six rabbits in the first group were not given any treatment, whereas 500 mg intramuscular ascorbic acid twice daily for 2 1/2 days was given to the six rabbits in the second group. Transient evoked otoacoustic emissions were recorded in all animals before and after noise exposure. Total protein sulfhydryl groups, carbonyl contents, and malondialdehyde levels, as well as erythrocyte glutathione, superoxide dismutase, and catalase enzyme levels, were measured in all rabbits. All the rabbits were exposed to noise (100 dB sound pressure level, 1000 Hz, 1 h), and transient evoked otoacoustic emissions were recorded again. RESULTS: When oxidative parameters before noise exposure were compared, erythrocyte glutathione and catalase enzyme levels were detected to be higher in the second group (P <.05). In the first group of rabbits after noise exposure, total protein sulfhydryl groups were found to be reduced (P <.05), whereas plasma carbonyl contents and malondialdehyde levels were elevated significantly (P <.05). In this group, erythrocyte glutathione, superoxide dismutase, and catalase enzyme levels were low (P <.05). In the second group, which was given ascorbic acid, total protein sulfhydryl groups were reduced (P <.05), whereas plasma carbonyl contents and malondialdehyde levels did not change (P >.05) following noise exposure. In the second group, erythrocyte glutathione and catalase enzyme levels were reduced (P <.05), but superoxide dismutase levels did not change (P >.05). Transient evoked otoacoustic emissions after noise exposure were weak in both groups, but reproducibility and signal-to-noise ratios were higher in the second group (P <.05). CONCLUSION: Ascorbic acid treatment inhibited both lipid peroxidation and oxidative damage of proteins in rabbits exposed to noise. The study data suggest, at least, that oxidative status should be included in the physiopathology of noise-induced hearing loss; in addition, a brief application of ascorbic acid before noise exposure appeared to play a protective role for cochlea.

Animals↗
PubMed1993

Influence of large doses of ascorbic acid on performance, plasma calcium, bone characteristics, and eggshell quality in broilers and Leghorn hens.

Four experiments were conducted using broilers (Experiments 1 and 2) or White Leghorn hens (Experiments 3 and 4) to determine the effects of large doses of dietary ascorbic acid on performance, plasma concentration of total and ionic calcium, bone characteristics, and eggshell quality. A total of 564 male broilers were fed diets containing ascorbic acid (ranging from 0 to 3,000 ppm) from 3 to 7 wk of age. Weight gain and feed conversion were measured, and blood plasma was analyzed for total and ionic calcium. Leg bones (femur, tibia, and metatarsus) were analyzed for bone mineral content, density, and breaking strength. In Experiments 3 and 4, a total of 484 Leghorn hens were fed diets containing ascorbic acid (ranging from 0 to 3,000 ppm) for 4 wk. Egg weight and specific gravity were determined, and plasma and tibiae were analyzed as in Experiments 1 and 2. Results of the broiler experiment (Experiment 2) indicated that plasma ionic calcium was significantly increased (P < .05) in ascorbic-acid-treated birds. Among leg bones examined, femur strength was improved by 16% in birds fed 2,000 ppm of ascorbic acid (Experiment 2). Other bone characteristics were not affected. In the layer experiments (Experiments 3 and 4), egg weight increased up to 5% and egg specific gravity was improved in hens fed 2,000 or 3,000 ppm of ascorbic acid, which also had increased calcium in the blood. Results suggest that large doses of ascorbic acid in the diet influence calcium metabolism, affecting bone and eggshell mineralization in chickens.

Animals↗
PubMed1983

Inhibition of bacterial multiplication by the iron chelator deferoxamine: potentiating effect of ascorbic acid.

Since iron is essential for the multiplication of microorganisms, the effect of the iron chelator deferoxamine, with or without ascorbic acid, on the growth of 43 strains of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Alcaligenes faecalis, Neisseria meningitidis and species of Salmonella, Enterobacter, Pseudomonas and Providencia, was investigated with the use of an automated turbidimeter. Addition of deferoxamine (25-400 micrograms/ml) to the incubation medium was inhibitory in a dose-dependent fashion. At concentrations between 200-400 micrograms/ml, growth was about 25% lower than control values. However, when ascorbic acid (100 micrograms/ml) was added to the culture medium, this antimicrobial activity of deferoxamine was significantly increased to on average 75% of the control value (p less than 0.05). Ascorbic acid alone had no bacteriostatic properties. Growth in the presence of 200 micrograms/ml deferoxamine combined with 100 micrograms/ml ascorbic acid was significantly lower than that in control media without additions (p less than 0.001). Addition of ferric citrate to the culture medium at a concentration sufficient to saturate all of the deferoxamine with iron, abolished the growth inhibiting effect of deferoxamine. The results provide evidence that deferoxamine is bacteriostatic due to its capacity to deplete iron which would otherwise be used for bacterial multiplication, and that ascorbic acid enhances this antibacterial property of deferoxamine.

Alcaligenes↗
PubMed1991

Ascorbic acid requirement for optimal flexor tendon repair in vitro.

Numerous studies from our laboratory have defined aspects of the repair process in a lacerated flexor tendon model, both in vivo and in vitro. Inherent in the development of a viable tissue or cell culture model system is the definition of the optimal media environment. Since our laboratory investigations of in vitro flexor tendon repair encompass the formation of numerous extracellular matrix proteins, we have defined the optimal level of ascorbic acid with which to study the tendon wound healing process. The ascorbic acid requirement for proline and lysine hydroxylase activity during collagen biosynthesis is well known, and the importance of this vitamin for matrix proteoglycan synthesis more recently has been appreciated. This report describes the effect of several levels of ascorbic acid on 3H-thymidine incorporation, collagen and noncollagen protein synthesis, and glucose utilization and lactate production. Profundus flexor tendon segments were obtained from young adult New Zealand white rabbits and maintained in organ culture for periods of 1, 2, or 3 weeks. Ascorbic acid concentrations ranged from 50 to 300 micrograms/ml and were added fresh at each 48-h media change. Tendon protein synthesis, glucose metabolism, and cell permeability/viability were significantly correlated with the level of ascorbic acid in the culture medium. The results suggest that ascorbic acid levels in excess of the traditional 50 micrograms/ml are necessary to optimally maintain flexor tendons from adult animals in organ culture with 48-h media and ascorbate changes. Additionally, it may be necessary to determine the precise ascorbic acid requirement for individual tissues, since the specific tissue/cell and species requirement for ascorbate may vary.

Animals↗
PubMed2003

[Plasma levels of ascorbic acid and vitamin E in patients with liver cirrhosis].

OBJECTIVE: To investigate the plasma levels of ascorbic acid and vitamin E in patients with liver cirrhosis and to explore their significance. METHODS: The plasma levels of ascorbic acid,vitamin E and lipoperoxides in patients with liver cirrhosis were measured, and the results were compared with those of sex-and age-matched healthy subjects. RESULT: The plasma levels of ascorbic acid, vitamin E and lipoperoxides in the patients group were (42.94 +/-6.99)micromol/L, (17.99 +/-3.51)micromol/L and (14.09 +/-1.28)micromol/L, respectively, while those in the control group were (53.30 +/-9.45)micromol/L (t=9.50, P=0.000), (24.59 +/-7.22)micromol/L (t=7.94, P=0.000) and (12.11 +/-1.20)micromol/L (t=17.21, P=0.000), respectively. CONCLUSION: The levels of ascorbic acid and vitamin E in patients with liver cirrhosis decrease significantly,which may indicates the disturbance of balance between oxidation and antioxidation.

Adult↗
PubMed1991

Gastric juice ascorbic acid: effects of disease and implications for gastric carcinogenesis.

N-nitroso compounds (NOC) are strongly implicated in the causation of cancer of the stomach and it has been suggested that ascorbic acid might reduce the risk of gastric cancer by preventing their formation within gastric juice. However, until recently there have been no measurements of gastric juice ascorbic acid concentrations. We have measured both gastric juice ascorbic and total vitamin C (ascorbic acid and dehydroascorbic acid). Our findings suggest that ascorbic acid is secreted into the gastric lumen so that gastric juice concentrations are often greater than those in plasma. Gastric pathology affects this secretion, leading to values in gastric juice that are lower than plasma levels. Stimulation of gastric secretion does not raise vitamin C concentrations in individuals whose values are initially low. The role of ascorbic acid in preventing formation of NOC and protecting against gastric cancer is discussed in the light of these findings.

Ascorbic Acid↗
PubMed2003

Ascorbic acid spares alpha-tocopherol and decreases lipid peroxidation in neuronal cells.

Ascorbic acid is considered an antioxidant in the central nervous system, but direct evidence that ascorbate protects neuronal cells from oxidant stress is lacking. Differentiated SH-SY5Y cells in culture took up ascorbic acid on the sodium-dependent vitamin C transporter Type 2 and retained it much more effectively than dehydroascorbic acid. Intracellular ascorbate spared alpha-tocopherol, both in cells loaded with alpha-tocopherol in culture and in cells under oxidant stress due to extracellular ferricyanide. Sparing of alpha-tocopherol in response to ferricyanide was associated with protection against lipid peroxidation in cell membranes. These results show that neuronal cells concentrate ascorbate, and that intracellular ascorbate, either directly or through sparing of alpha-tocopherol, protects them against oxidant stress.

Ascorbic Acid↗
PubMed1984

Theophylline clearance. Lack of effect of influenza vaccination and ascorbic acid.

Warnings have been issued regarding safety in the use of theophylline preparations in patients receiving influenza vaccination. These were prompted by reports that influenza vaccination caused inhibition of metabolism of theophylline and aminopyrine. Previous work has indicated a role for ascorbic acid in mixed function oxidase activity, and ascorbic acid is commonly used by the public. We studied the effect of influenza vaccination and ascorbic acid supplementation on the rate of elimination of theophylline. In 11 patients and 12 normal subjects no significant effects of influenza vaccination or ascorbic acid supplementation on theophylline clearance, serum half-life, or apparent volume of distribution were detected (p greater than 0.3). We conclude that neither influenza vaccination nor ascorbic acid supplementation induce a predictable effect on theophylline disposition.

Adult↗
PubMed1977

Effect of ascorbic acid on tumour growth.

The growth of tumours in guinea-pigs was observed for 20 weeks after placing them on various doses of vitamin C. Complete tumour regression occurred in 55% of those animals receiving 0-3 mg/kg/day ascorbic acid, whereas animals given 10 mg/kg/day showed tumour inhibition but no regression. In contrast, tumours in animals maintained on 1 g/kg/day ascorbic acid grew without sign of retardation. When increased amounts of ascorbic acid were restored to the diet of scorbutic tumour-bearing animals, tumours which had not regressed responded with enhanced growth. Likewise, animals previously maintained on 10 mg/kg ascorbic acid responded in turn to the additional vitamin with enhanced tumour growth. In contrast, all tumour-bearing animals maintained on 1 g/kh ascorbic acid died within 3 weeks when this dose was replaced with 0-3 mg/kg.

Animals↗
PubMed2003

Ascorbic acid reduces the frequency of iron induced micronuclei in bone marrow cells of mice.

Iron is a potent oxidant that can lead to the formation of genotoxic lipid peroxides. Ascorbic acid, which enhances dietary iron absorption, has been suggested to enhance the oxidant effects of iron and to directly lead to the formation of lipid peroxides. The combined effects of dietary iron and ascorbic acid on genotoxicity were investigated by measuring the frequency of micronuclei in the bone marrow cells of C3H/He mice. In addition, liver iron concentration was measured in all treated groups. Three weeks old mice were fed diets for 3 weeks containing iron at 100 or 300 mg/kg diet in the form of FeSO(4) that were supplemented either with or without ascorbic acid (15 g/kg diet). The results of the bone marrow micronucleus test revealed that the high iron diet resulted in an increased frequency of micronucleated polychromatic erythrocytes (MnPCEs) as compared to low iron. Ascorbic acid supplementation in the low iron diet did not show any effect on incidence of MnPCEs and protected against the increased frequency of MnPCEs induced by the high iron diet. However, liver iron concentration was significantly increased only in the high iron treated and ascorbic acid supplemented group as compared to all other groups. These results demonstrate that ascorbic acid protects against the clastogenic effects of iron.

Administration, Oral↗
PubMed2000

A prospective study of plasma ascorbic acid concentrations and breast cancer (United States).

OBJECTIVES: To investigate the association between prediagnostic plasma ascorbic acid concentrations and subsequent breast cancer risk in a nested case-control study. METHODS: Female volunteer residents of Washington County, MD, donated 14,625 non-fasting blood samples in 1989. Incident breast cancer cases (n = 115) and controls (n = 115) were matched by age, menopausal status at donation, and date and hour of blood donation. RESULTS: Median ascorbic acid concentrations were similar between cases and controls (1.44 mg/dl vs. 1.39 mg/dl. p = 0.78). There was no evidence for a dose-response relationship between higher plasma ascorbic acid concentrations and breast cancer risk [highest vs. lowest fifths: ORadjusted = 0.90, Ptrend = 0.98). CONCLUSIONS: Findings from this prospective study do not suggest a protective association between prediagnostic plasma ascorbic acid concentrations and breast cancer risk in the subsequent 5 years of follow-up.

Ascorbic Acid↗
PubMed1999

Large-dose ascorbic acid administration suppresses the development of arthritis in adjuvant-infected rats.

We performed animal experiments to test the hypothesis that active oxygen species (AOS) play a major role in adjuvant-induced arthritis in rats and to determine whether large-dose ascorbic acid administration would suppress the development of arthritis, reducing the level of damaging AOS in the same animal model. Arthritis was induced in male Lewis rats by adjuvant injection into the base of the tail. Ascorbic acid at doses of 0.5, 1.0, and 2.0 g/kg body weight (BW) was injected intraperitoneally twice each week for 3 weeks (9 rats per group). The BW, hind paw edema, and arthritis score of the extremities were monitored during the period. On day 21, synovial tissues obtained from the ankle joints were examined histologically and for the activity of superoxide dismutase (SOD). The SOD activity in the red blood cells (RBC) was also measured. The arthritic control rats showed significant increases in paw volume and arthritis score from day 11. These changes were dose-dependently reduced by ascorbic acid administration. The infiltration of inflammatory cells into the synovial tissues was markedly decreased by ascorbic acid. The increases in SOD activities produced by the adjuvant injection were significantly reduced in both the synovium and the RBC at ascorbic acid doses of 1.0 and 2.0 g/kg BW. In conclusion, large-dose ascorbic acid administration reduced the increases in hind paw inflammatory edema, arthritis in the extremities, and infiltration of the inflammatory cells into the synovial tissue in the adjuvant-induced arthritis rats. Since these anti-arthritic effects were associated with a decrease in SOD activities in both the synovium and RBC, the decrease in SOD activity could be one of the mechanisms underlying the suppressive effects of large-dose ascorbic acid on the development of arthritis in this animal model, inhibiting the damaging AOS.

Animals↗
PubMed2004

Effects of vitamin C supplementation on plasma ascorbic acid and oxalate concentrations and meat quality in swine.

Two experiments were conducted to determine the effects of vitamin C supplementation 48 h before slaughter on plasma ascorbic acid and oxalate concentrations and its effect on pork quality. In Exp. 1, 16 pigs (87.8+/-2.13 kg BW) were blocked by sex and weight and assigned randomly within block to one of three vitamin C treatments: 1) control; 2) 1,000 mg/L; or 3) 2,000 mg/L supplemented in the drinking water for a 48-h period. This was then followed by an additional 48-h period without supplemental vitamin C. Vitamin C increased plasma ascorbic acid concentrations (11.6, 19.5, and 23.4 microg/mL for 0, 1,000, and 2,000 mg/L of vitamin C; P < 0.05) within 6 h of supplementation. Plasma ascorbic acid concentrations from treated pigs decreased and did not differ from those of control pigs (13.7, 18.2, and 18.6 microg/mL for 0, 1,000, and 2,000 mg/L of vitamin C; P = 0.30) within 2 h of ending supplementation. No differences in plasma ascorbic acid concentrations were found between the two levels of supplementation. Vitamin C did not affect plasma oxalate or cortisol; however, cortisol tended to increase quadratically (P = 0.077) with vitamin C after 96 h. In Exp. 2, 30 pigs (107.5+/-0.54 kg BW) were blocked by sex and weight and assigned randomly within block to one of three vitamin C treatments: 1) control; 2) 500 mg/L; or 3) 1,000 mg/L supplemented in the drinking water 48 h before slaughter. Pigs were slaughtered 4 to 5 h after vitamin C supplementation ended, and loin samples were collected for meat quality measurements. At the time of slaughter, no differences in plasma ascorbic acid or cortisol were observed, but oxalate tended (P = 0.074) to increase quadratically with increasing vitamin C. Muscle ascorbic acid at slaughter and lactic acid in muscle at 0 and 1.5 h after slaughter were not different; however, lactic acid increased (P = 0.048) quadratically at 24 h after slaughter. Vitamin C did not affect initial or ultimate pH. Initial fluid loss (P = 0.041), and fluid loss on d 4 (P = 0.014) and 8 (P = 0.076) of simulated retail display; L* on d 0 (P = 0.038), 4 (P = 0.010), and 8 (P = 0.051); a* on d 0 (P = 0.021); and b* on d 0 (P = 0.006), 4 (P = 0.035), and 8 (P = 0.017) were negatively affected in a quadratic manner when vitamin C was supplemented. Vitamin C tended (P = 0.086) to increase oxidation in chops on d 0, but not d 4 or 8. Results indicate that on-farm supplementation of vitamin C was generally not effective in improving pork quality, which may be related to timing relative to slaughter.

Animal Feed↗
PubMed1997

Influence of ascorbic acid on the response to mitogens and interleukin production of porcine lymphocytes.

The influence of ascorbic acid (AA) on lymphocyte functions was examined in vitro and ex vivo in peripheral blood mononuclear cells (PBMC) of vitamin C-deficient pigs, which are unable to synthesise ascorbic acid. AA is accumulated to physiological levels in PBMC in vitro. The cell proliferation induced by T lymphocyte mitogens was unaltered at all AA concentrations tested (0-400 micrograms/ml, i.e., 0-2.3 mM). Conversely, the response to pokeweed mitogen (PWM) which activates T and B lymphocytes was significantly reduced with increasing intracellular and extracellular AA concentrations. The response to lipopolysaccharide (LPS) showed a tendency to increase at low (9 microM) and was significantly reduced at high AA concentrations (> 36 microM). The IL2 production induced by PWM (but not by concanavalin A (Con A) or phytohemagglutinin (PHA)) decreased at high AA (> 142 microM). In contrast, IL6 production induced by mitogens was not dependent on AA concentrations. In concordance with these results, AA-depleted PBMC which were obtained from pigs that were fed an AA-free diet, displayed an increasing response to LPS and PWM. Collectively, the data indicate that ascorbic acid selectively influences the proliferation of B lymphocytes and negatively acts on IL2 production by T lymphocytes when a threshold of saturation is exceeded.

Animals↗
PubMed1984

The relative effect of ascorbic acid on iron absorption from soy-based and milk-based infant formulas.

The effect of varying concentrations of ascorbic acid on the absorption of iron from a soy-based infant milk formula containing 6 mg iron/100 g was examined in 64 adult Indian females using the extrinsic radioactive tag method. The corrected geometric mean absorption from the basic soy formula was only 1.8%. Addition of ascorbic acid in a concentration of 40 mg/100 g, did not significantly increase absorption (3.3%; t = 1.8, p greater than 0.07) but raising the concentration to 80 mg/100 g did so (6.9%; t = 2.4, p less than 0.02). No further significant increase was noted when the concentration of ascorbic acid was increased to 160 mg/100 g (7.7%; t = 0.4, p greater than 0.7). The inhibitory effect of soy on iron absorption was further demonstrated by a direct comparison between the soy-based formula and a similar product based on cows' milk. The comparison was made at two concentrations of ascorbic acid. At 40 mg/100 g the geometric mean iron absorption from the soy formula was 2.4% compared with 5.3% from the milk formula (t = 2.8, p less than 0.02), while the corresponding values at 80 mg ascorbic acid/100 g were 7.2 and 19.5%, respectively (t = 3.4, p less than 0.02). The present results confirm the marked inhibitory effect of soy protein on iron absorption and calculations from the absorption figures suggest that such formulas should contain at least 12 mg/100 g iron together with ascorbic acid in a molar ratio of approximately 4:1 if they are to be adequate in terms of iron nutrition.

Anemia, Hypochromic↗
PubMed1988

Effects of active oxygen scavengers on the peroxidation of linoleic acid catalyzed by dehydro-L-ascorbic acid or its degradation products.

The addition of 1,4-diazabicyclo-[2,2,2]octane (DABCO) (100 mM) or 1,2-dihydroxybenzene-3,5-disulfonic acid (Tiron) (1 mM) to a reaction mixture containing 10 mM linoleic acid (LA), 20% EtOH, and 135 microM dehydroascorbic acid (DHA) as a catalyst suppressed LA peroxidation, but the addition of mannitol (approximately 100 mM), uric acid (100 microM), and catalase (6.5 units) did not. DHA or 2,3-diketo-L-gulonic acid (DKG) accelerated LA peroxidation, but the splitting products of DHA did not affect LA peroxidation. These results suggest that some specific radicals are liberated in the degradation of DHA or DKG.

1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium ↗