Vitamins C and E prevent AZT-induced leukopenia and loss of cellularity in bone marrow. Studies in mice

A major limitation in the use of AZT for AIDS treatment is the occurrence of side effects, such as leukopenia. The effects of antioxidant vitamins C and E on AZT-induced leukopenia were investigated in mice. Mice were divided into four groups: (1) controls; (2) AZT-treated; (3) treated with AZT plus vitamins C and E; and (4) pre-treated with vitamins and then treated with AZT plus vitamins. Our results demonstrate that AZT causes leukopenia in mice, which was abrogated by administration of vitamins C and E in the pre-treated group. These vitamins prevented the decrease in cellular content induced by AZT in bone marrow and diminished peroxide levels in myeloid precursors in bone marrow. AZT also caused an increase in plasma malondialdehyde and blood oxidized glutathione levels, which was prevented by the administration of antioxidant vitamins. In conclusion, oxidative stress is involved in AZT-induced leukopenia which may be prevented by antioxidant treatment.     

Vitamins C and E prevent AZT-induced leukopenia and loss of cellularity in bone marrow. Studies in mice

A major limitation in the use of AZT for AIDS treatment is the occurrence of side effects, such as leukopenia. The effects of antioxidant vitamins C and E on AZT-induced leukopenia were investigated in mice. Mice were divided into four groups: (1) controls; (2) AZT-treated; (3) treated with AZT plus vitamins C and E; and (4) pre-treated with vitamins and then treated with AZT plus vitamins. Our results demonstrate that AZT causes leukopenia in mice, which was abrogated by administration of vitamins C and E in the pre-treated group. These vitamins prevented the decrease in cellular content induced by AZT in bone marrow and diminished peroxide levels in myeloid precursors in bone marrow. AZT also caused an increase in plasma malondialdehyde and blood oxidized glutathione levels, which was prevented by the administration of antioxidant vitamins. In conclusion, oxidative stress is involved in AZT-induced leukopenia which may be prevented by antioxidant treatment.     

Changes observed in antioxidant system in the blood of postmenopausal women with breast cancer.

From experimental studies and epidemiological data, it can be inferred that lipid peroxidation is increased in cancer patients. Cases of post-menopausal, untreated women with benign and malignant breast tumours, were compared with their age matched controls in their serum lipid peroxides, antioxidant vitamins (E and C), serum selenium and serum ceruloplasmin. Erythrocyte and its membrane lipid peroxidation and antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase and glutathione-S-transferase) levels were also analyzed. Significant increase in circulating lipid peroxides, ceruloplasmin and significant decrease in antioxidant vitamins and selenium were observed in breast cancer women. The erythrocyte and its membrane lipid peroxidation was increased significantly and severe impairment of antioxidant potential was observed in breast cancer women.     

Levels of plasma vitamin E,vitamin C,TBARS, and cholesterol in male patients with colorectal tumors

Vitamin E and vitamin C are involved in the defense of the body against free radical and reactive oxygen molecule induced damage. The best characterized biological damage caused by radicals is known as lipid peroxidation. Free radical formation is known to play a major role in the development of cancer. In this study, we measured plasma levels of thiobarbituric acid reactive substances (TBARS) as a marker of lipid peroxidation, cholesterol, and vitamins E and C as antioxidants in male patients with colorectal tumors (n = 20, 54.5 ± 8.3 years). The patients had significantly higher plasma TBARS levels than age-matched healthy subjects (p < 0.001). Plasma vitamin C levels were significantly lower in the patients compared to the healthy subjects (p < 0.001). On the other hand, plasma vitamin E levels in the patients were similar to those of healthy subjects. Plasma cholesterol levels were also found to be significantly elevated in patients with colorectal tumors (p < 0.001). Our results suggest that there is an imbalance between oxidant and antioxidant status in tumor genesis.     

Modulation of restraint stress induced oxidative changes in rats by antioxidant vitamins

In the present study we examined immobilization stress-induced antioxidant defense changes in rat plasma and also observed the antioxidant effects of pre and post vitamins A, E and C administration (15 mg/Kg of body weight) individually and in combination (vit E + C) on these alterations.Following immobilization stress the circulating activities of superoxide dismutase, catalase and glutathione-S-transferase were decreased, while the level of thiobarbituric acid reactive substances (TBARS) was increased as compared to non-stressed control rats.Post treatment with individual vitamins A, E and C (after exposure to stress) resulted in a less marked alteration of plasma TBARS levels and activities of SOD, GST and catalase as compared to pre vitamin stress or stress alone treatments. Both pre and post vitamin treatments were effective in preventing stress induced derangement of free radical metabolism with a relative dominance by latter. The combined treatment with vitamin E and C did not show any additive antioxidant effect on restraint stress induced altered free radical metabolism, rather a predominant effect similar to vitamin E alone was observed. The prevention of oxidative stress generated in response to restraint stress by the vitamins can be summarized as: vitamin (E + C) i.e. vit E > vit C > vit A, thus combined vitamin (E + C) treatment though showed maximum preventive effect, but was similar to vitamin E treatment alone, in terms of the circulating activities of SOD, GST, catalase and TBARS levels.     

Exercise-induced brachial artery vasodilation: role of free radicals

Originally thought of as simply damaging or toxic "accidents" of in vivo chemistry, free radicals are becoming increasingly recognized as redox signaling molecules implicit in cellular homeostasis. Indeed, at the vascular level, it is plausible that oxidative stress plays a regulatory role in normal vascular function. Using electron paramagnetic resonance (EPR) spectroscopy, we sought to document the ability of an oral antioxidant cocktail (vitamins C, E, and alpha-lipoic acid) to reduce circulating free radicals, and we employed Doppler ultrasound to examine the consequence of an antioxidant-mediated reduction in oxidative stress on exercise-induced vasodilation. A total of 25 young (18-31 yr) healthy male subjects partook in these studies. EPR spectroscopy revealed a reduction in circulating free radicals following antioxidant administration at rest ( approximately 98%) and as a consequence of exercise ( approximately 85%). Plasma total antioxidant capacity and vitamin C both increased following the ingestion of the antioxidant cocktail, whereas vitamin E levels were not influenced by the ingestion of the antioxidants. Brachial artery vasodilation during submaximal forearm handgrip exercise was greater with the placebo (7.4 +/- 1.8%) than with the antioxidant cocktail (2.3 +/- 0.7%). These data document the efficacy of an oral antioxidant cocktail in reducing free radicals and suggest that, in a healthy state, the aggressive disruption of the delicate balance between pro- and antioxidant forces can negatively impact vascular function. These findings implicate an exercise-induced reliance upon pro-oxidant-stimulated vasodilation, thereby revealing an important and positive vascular role for free radicals.     

Vitamins C and E improve rat embryonic antioxidant defense mechanism in diabetic culture medium.

BACKGROUND: Diabetes teratogenicity seems to be related to embryonic oxidative stress and the extent of the embryonic damage can apparently be reduced by antioxidants. We have studied the mechanism by which antioxidants, such as vitamins C and E, reduce diabetes-induced embryonic damage. We therefore compared the antioxidant capacity of 10.5-day-old rat embryos and their yolk sacs cultured for 28h in diabetic culture medium with or without vitamins C and E. METHODS: The embryos were cultured in 90% rat serum to which 2mg/ml glucose, 2mg/ml beta hydroxy butyrate (BHOB) and 10 microg/ml of acetoacetate were added. Rat embryos were also cultured in a diabetic medium with 25 microg/ml of vitamin E and 50 microg/ml of vitamin C. Control embryos were cultured in normal rat serum with or without vitamins C and E. RESULTS: Decreased activity of Cu/Zn superoxide dismutase (SOD) and of catalase (CAT) in the "diabetic" embryos and their yolk sacs, and reduced concentrations of low molecular weight antioxidant (LMWA) were found. Under these conditions we also found a decrease in vitamin C and vitamin E concentrations in the embryos, as measured by HPLC. In situ hybridization for SOD mRNA showed a marked reduction of SOD mRNA in the brain, spinal cord, heart and liver of embryos cultured in diabetic medium in comparison to controls. Following the addition of vitamins C and E to the diabetic culture medium, SOD and CAT activity, the concentrations of LMWA, the levels of vitamin C and E and the expression of SOD mRNA in the embryos and yolk sacs returned to normal. CONCLUSIONS: Diabetic metabolic factors seem to have a direct effect on embryonic SOD gene and perhaps genes of other antioxidant enzymes, reducing embryonic endogenous antioxidant defense mechanism. This in turn may cause a depletion of the LMWA, such as vitamins C and E. The addition of these vitamins normalizes the embryonic antioxidant defense mechanism, reducing the damage caused by the diabetic environment.     

Effects of X-ray radiation on lipid peroxidation and antioxidant systems in rabbits treated with antioxidant compounds

The aim of this study was to investigate the effects of supplemental antioxidant vitamins and minerals on lipid peroxidation and on the antioxidant systems in rabbits exposed to X-rays. The rabbits were divided into two experimental groups and one control group, each group containing seven rabbits. The first group (VG) received daily oral doses of vitamin E (460 mg/kg live weight) and vitamin C (100 mg/kg live weight). The second group (MG) was fed a mineral-enriched diet that contained 60 mg manganese chloride, 40 mg zinc sulfate, and 5 mg copper sulfate per kilogram of feed. The third group served as controls and received only a standard diet. Blood samples were obtained before and after the supplementation with vitamins or minerals, as well as before and after irradiation with a total dose of 550-rad X-rays. The blood samples were analyzed for their content of malondialdehyde (MDA), plasma vitamins C and E, retinol, reduced glutathione (GSH), and glutathione peroxidase activity (GPx). After irradiation, the control group showed increased levels of MDA and activity of GPx (p<0.05), whereas the levels of GSH, vitamin C, and vitamin E were decreased. In the VG, the concentration of MDA was lower (p<0.05), and the concentration of GSH and vitamins C and E were higher (p<0.05) when compared to controls. In the MG, the concentrations of MDA, GSH, vitamin C, and retinol were not affected by the mineral administration and radiation. The level of vitamin E in the MG increased with mineral administration (p<0.05), but decreased after irradiation (p<0.05). For the control group, the level of GSH was higher than in the two experimental groups. After irradiation, the VG animals had vitamin E and C levels that were higher than in MG and control groups (p<0.05). The activity of GPx was not affected by vitamin or mineral supplementation or by irradiation. We conclude that the supplementation with antioxidant vitamins and minerals may serve to reinforce the antioxidant systems, thus having a protective effect against cell damage by X-rays.     

Vitamins C and E donate single hydrogen atoms in vivo.

The antioxidant vitamins, C and E, eliminate cytotoxic free radicals by redox cycling. Energetic and kinetic considerations suggest that cycling of vitamin C and vitamin E between their reduced and free radical forms occurs via the transfer of single hydrogen atoms rather than via separate electron transfer and protonation reactions. This may enable these vitamins to reduce many of the damaging free radicals commonly encountered by biological systems while minimizing the reduction of molecular oxygen to superoxide.     

Oxidative stress and antioxidant deficiencies in asthma: potential modification by diet

The lungs of asthmatic patients are exposed to oxidative stress due to the generation of reactive oxygen and nitrogen species as a consequence of chronic airway inflammation. Increased concentrations of NO*, H2O2 and 8-isoprostane have been measured in exhaled breath and induced sputum of asthmatic patients. O2*-, NO*, and halides interact to form highly reactive species such as peroxynitrite and HOBr, which in turn cause nitration and bromination of protein tyrosine residues. Oxidative stress may also reduce glutathione levels and cause inactivation of antioxidant enzymes such as superoxide dismutase, with a consequent increase in apoptosis, shedding of airway epithelial cells and airway remodelling. The oxidant/antioxidant equilibrium in asthmatic patients may be further perturbed by low dietary intakes of the antioxidant vitamins C and E, selenium and flavonoids, with a consequent lowering of the concentrations of these and other non-dietary antioxidants such as bilirubin and albumin in plasma and airway epithelial lining fluid. Although supplementation with vitamins C and E appears to offer protection against the adverse effects of ozone, recent randomised, placebo-controlled trials of vitamin C or E supplements for patients with mild asthma have not shown significant benefits over standard therapy. However, genetic variation in glutathione S-transferase may influence the susceptibility of asthmatic individuals to oxidative stress and the extent to which they are likely to benefit from antioxidant supplementation. Long-term prospective trials are required to determine whether modification of dietary intake will benefit asthma patients and reduce the socio-economic burden of asthma in the community.     

Vitamin C partially reversed some biochemical changes produced by vitamin E deficiency

Feeding a basal diet free of vitamins E and C to weanling male rats for 8 months resulted in biochemical changes characteristic of vitamin E deficiency. These included increased liver thiobarbituric acid values; decreased blood GSH levels, plasma vitamin E levels, and glutathione peroxidase activities; and increased activities of plasma pyruvate kinase, glutamic-oxaloacetic transaminase, creatine kinase, lactic dehydrogenase, and malic dehydrogenase. Tube-feeding vitamin C for 21 days resulted in partial reversal effects on the above parameters except activities of glutathione peroxidase, lactic dehydrogenase, and malic dehydrogenase. The results suggest that vitamin C may spare in part the metabolism of vitamin E through its antioxidant property.     

Investigation of antioxidant vitamins (A,E and C) and selenium levels in chickens receiving estrogen or testosterone

In the present study estrogen or testosterone was administered to broiler chickens (6 weeks old) for 5 weeks and levels of antioxidant vitamins (A, E and C) and selenium (Se) were determined. In animals who received estrogen, vitamins A, E, C and Se levels were 0.70 +/- 0.19, 11.0 +/- 2.45, 20.0 +/- 5.17 and 130.0 +/- 25.0 microg l(-1), respectively. Vitamins A, E, C and Se levels in the testosterone-administered group were found to be 0.54 +/- 0.16, 9.9 +/- 1.96, 18.0 +/- 5.18 and 100.0 +/- 18.0 microg l(-1), respectively. Vitamins A, E, C and Se levels were found to be significantly increased in the estrogen-administered group compared to the controls (p < 0.01, p < 0.01, p < 0.05, p < 0.05, respectively). Although all parameters were increased in testosterone-treated animals, only increases in vitamins A and E were found to be statistically significant (p < 0.01, p < 0.01, respectively). Based on the present findings, estrogen and testosterone show direct antioxidant effects by increasing the activities of some enzymes and they also cause an increase in antioxidant vitamin levels and hence indirectly also contribute to antioxidant capacity.     

Protective antioxidant effect of vitamins C and E in streptozotocin induced diabetic rats

We have investigated the protective effect of vitamin C and E together supplementation on oxidative stress and antioxidant enzyme activities in the liver of streptozotocin-induced diabetic rats, unsupplemented diabetic and control rats. We also determined the levels of both the vitamins and oxidative stress in plasma. Vitamin supplementation in diabetic rats lowered plasma and liver lipid peroxidation, normalised plasma vitamin C levels and raised vitamin E above normal levels. In liver, the activity of glutathione peroxidase was raised significantly and that of glutathione-S-transferase was normalised by vitamin supplementation in diabetic rats. The levels of lipid peroxidation products in plasma and liver of vitamin-supplemented diabetic rats and activities of antioxidant enzymes in liver suggest that these vitamins reduce lipid peroxidation by quenching free radicals.     

Breath alkanes as a marker of oxidative stress in different clinical conditions

We assessed oxidative stress in three different clinical conditions: smoking, human immunodeficiency virus (HIV) infection, and inflammatory bowel disease, using breath alkane output and other lipid peroxidation parameters such as plasma lipid peroxides (LPO) and malondialdehyde (MDA). Antioxidant micronutrients such as selenium, vitamin E, C, beta-carotene and carotenoids were also measured. Lipid peroxidation was significantly higher and antioxidant vitamins significantly lower in smokers compared to nonsmokers. Beta-carotene or vitamin E supplementation significantly reduced lipid peroxidation in that population. However, vitamin C supplementation had no effect. In HIV-infected subjects, lipid peroxidation parameters were also elevated and antioxidant vitamins reduced compared to seronegative controls. Vitamin E and C supplementation resulted in a significant decrease in lipid peroxidation with a trend toward a reduction in viral load. In patients with inflammatory bowel disease, breath alkane output was also significantly elevated when compared to healthy controls. A trial with vitamin E and C is underway. In conclusion, breath alkane output, plasma LPO and MDA are elevated in certain clinical conditions such as smoking, HIV infection, and inflammatory bowel disease. This is associated with lower levels of antioxidant micronutrients. Supplementation with antioxidant vitamins significantly reduced these lipid peroxidation parameters. The results suggest that these measures are good markers for lipid peroxidation.     

Oxidant,antioxidant and physical exercise

Generation of reactive oxygen species (ROS) is a normal process in the life of aerobic organisms. Under physiological conditions, these deleterious species are mostly removed by the cellular antioxidant systems, which include antioxidant vitamins, protein and non-protein thiols, and antioxidant enzymes. Since the antioxidant reserve capacity in most tissues is rather marginal, strenuous physical exercise characterized by a remarkable increase in oxygen consumption with concomitant production of ROS presents a challenge to the antioxidant systems.An acute bout of exercise at sufficient intensity has been shown to stimulate activities of antioxidant enzymes. This could be considered as a defensive mechanism of the cell under oxidative stress. However, prolonged heavy exercise may cause a transient reduction of tissue vitamin E content and a change of glutathione redox status in various body tissues. Deficiency of antioxidant nutrients appears to hamper antioxidant systems and augment exercise-induced oxidative stress and tissue damage. Chronic exercise training seems to induce activities of antioxidant enzymes and perhaps stimulate GSH levels in body fluids. Recent research suggest that supplementation of certain antioxidant nutrients are necessary for physically active individuals.     

Dietary supplementation with antioxidants. Is there a case for exceeding the recommended dietary allowance?

The containment of damaging oxygen species by antioxidant nutrients has led to the speculation that the RDA for these specific nutrients may be overly low. Among these nutrients are vitamin E, vitamin C, and to a lesser extent beta-carotene and selenium. Evidence for the role of these nutrients in cancer and heart disease is evaluated. The case is presented for an increase of two-fold for the vitamin C RDA and between three and five-fold for vitamin E; for establishing 15 mg as the RDA for beta-carotene; for no change in the vitamin A RDA; and for further study on selenium.     

Effect of One-Year Vitamin C- and E-Supplementation on Cerebrospinal Fluid Oxidation Parameters and Clinical Course in Alzheimer’s Disease

Antioxidant vitamins are being widely discussed as a therapeutic option in Alzheimer??s disease (AD). We recently found that supplementation with vitamin C and E over 1?month leads to an increase of their levels in cerebrospinal fluid (CSF) and a reduction of CSF lipid peroxidation. In the present study, we followed-up the biochemical and clinical effect of vitamin C and E supplementation in an open clinical trial over 1?year. Twelve AD patients stably taking a cholinesterase inhibitor were supplemented with vitamin C (1,000?mg/day) and E (400 I.U./day), while 11 patients taking cholinergic medication only served as a control group. Cognition was assessed at baseline, after 6 months and 12 months using the Mini-Mental State Examination; a more detailed testing of cognitive function was performed at baseline and after 12 months. From eight of the vitamin-supplemented patients, CSF was taken at baseline, after 1?month and after 1?year to measure the antioxidant effect of vitamin supplementation on CSF lipids using a recently established in vitro oxidation assay. CSF antioxidant vitamins were significantly increased after 1?month and 1?year of supplementation, while in vitro oxidation of CSF lipids was significantly reduced only after 1?year of the supplementation. The clinical course of AD did not significantly differ between the vitamin and the control group. We conclude that supplementation with vitamins E and C did not have a significant effect on the course of AD over 1?year despite of a limited antioxidant effect that could be observed in CSF.     

Studies on the effects of x-ray on erythrocyte zinc and copper concentrations in rabbits after treatment with antioxidants

The aim of this study was to investigate the effect of supplemental antioxidant vitamins and minerals on the erythrocyte concentrations of zinc and copper in rabbits after exposure to X-rays. The animals were divided into two experimental and one control group (CG). The first group (VG) was given daily oral doses of vitamins E and C; supplemental amounts of managanese, zinc, and copper were mixed with the feed and given to the second group of experimental animals (MG). Blood samples were taken from all groups before and after 4 wk of vitamin and mineral administration and after irradiation with a total dose of 550-rad X-rays. The administration of minerals caused the most significant increases of Zn and Cu. Even after irradiation, the zinc levels in the irradiated animals were higher than in the nonirradiated vitamin-supplemented animals (p<0.05). The results suggest that supplementation with antioxidant vitamins and minerals may have a protective effect against X-ray-induced damage.     

Interaction of vitamin C and vitamin E during free radical stress in plasma: An ESR study

To study the interaction of the antioxidant vitamins C and E in a biological system, we used electron spin resonance (ESR) spectroscopy to make serial measurement of ascorbate tocopheroxyl free radicals in plasma subjected to continuous free radical-mediated oxidative stress. Upon initiation of a continuous oxidative stress, we observed an immediate increase in the concentration of ascorbate radical, which reached a peak, and then steadily declined. Only after the virtual disappearance of the ascorbate radical did we observe the appearance of the tocopheroxyl radical. These data are consistent with the hypothesis that ascorbate is the terminal small-molecule antioxidant in biological systems. This is the first experimental demonstration that the predicted thermodynamic hierarchy of ascorbate, -tocopherol, and their free radicals holds in a biological system containing endogenous levels of these antioxidant vitamins.     

Production of antioxidant vitamins, beta-carotene, vitamin C, and vitamin E, by two-step culture of Euglena gracilis Z

Euglena gracilis Z is one of the few microorganisms which simultaneously produces antioxidant vitamins such as beta-carotene and vitamins C and E. Photoheterotrophically cultured E. gracilis Z produced larger levels of biomass but with a lower content of antioxidant vitamins than photoautotrophically grown cultures. For efficient production of these vitamins, a two-step culture was performed. Cells were grown photoheterotrophically and then transferred to photoautotrophic conditions. When E. gracilis Z cells were grown in fed-batch culture under photoheterotrophic conditions, their density reached 19 g/L after 145 h. Subsequent transfer of these cells to photoautotrophic conditions increased vitamin content, enhancing the total vitamin yields, which were 71.0 mg/L of beta-carotene, 30.1 mg/L of vitamin E, and 86.5 mg/L of vitamin C. (c) 1997 John Wiley & Sons, Inc.