ascorbic-acid and vanadyl-sulfate

Using the comet assay, we showed that vanadyl sulfate induced DNA damage in human normal lymphocytes and in HeLa cells. Vanadyl at 0.5 and 1 mM produced DNA single- and double-strand breaks (SSBs and DSBs) in lymphocytes, whereas in HeLa cells we observed only SSBs. Post-treatment of vanadyl-damaged DNA from lymphocytes with formamidopyrimidine-DNA glycosylase (Fpg), an enzyme recognizing oxidized purines, gave rise to a significant increase in the extent of DNA damage. A similar effect was observed in HeLa cells, but, using endonuclease III, we also detected oxidized pyrimidines in DNA of these cells. There were no differences in the extent of DNA damage in the lymphocytes and HeLa cells in the pH >13 and pH 12.1 conditions of the comet assay, which indicates that strand breaks, and not alkali-labile sites, contributed to the measured DNA damage. Study of DNA repair, determined in the comet assay as an ability of cells to decrease of DNA damage, revealed that HeLa cells retained the ability to repair vanadyl-damaged DNA induced at a ten-fold higher concentration than that in lymphocytes. Incubation of the cells with nitrone spin traps DMPO, POBN and PBN decreased the extent of DNA damage, which might follow from the production of free radicals by vanadyl sulfate. The presence of vitamins A, C or E caused an increase of DNA damage in HeLa cells whereas in lymphocytes such an increase was observed only for vitamin C. Our data indicate that vanadyl sulfate can be genotoxic for normal and cancer cells. It seems to have a higher genotoxic potential for cancer cells than for normal lymphocytes. Vitamins A, C and E can increase this potential.

Topics: Ascorbic Acid; Cell Survival; Comet Assay; Deoxyribonuclease (Pyrimidine Dimer); DNA; DNA Damage; DNA Repair; DNA-Formamidopyrimidine Glycosylase; Dose-Response Relationship, Drug; Drug Combinations; Drug Synergism; Escherichia coli Proteins; HeLa Cells; Humans; Hydrogen-Ion Concentration; Hypoglycemic Agents; Lymphocytes; Mutagens; Spin Trapping; Vanadium Compounds

Vanadium has been shown to have a number of insulin-like effects and has been demonstrated to be beneficial in the treatment of streptozotocin-diabetic rats when included in the drinking water. However, some signs of toxicity and vanadium accumulation in all analysed tissues were reported in vanadium-treated animals. In the present study, the effect of repeated intraperitoneal administration of sodium 4,5-dihydroxybenzene-1,3-disulfonate (Tiron), ascorbic acid and deferoxamine mesylate (DFOA) or 2-mercaptosuccinic acid on the distribution and excretion of vanadium was determined in male Sprague-Dawley rats. Rats received sodium metavanadate (NaVO3) or vanadyl sulphate pentahydrate (VOSO4.5H2O) in the drinking water at concentrations of 0.15 mg ml-1 (NaVO3) and 0.31 mg ml-1 (VOSO4.5H2O) for 6 weeks. After the end of this exposure period, chelating agents were administered for 2 weeks (3 days per week) at doses approximately equal to one-tenth of their respective LD50. Urine was collected on days 1, 7 and 14 of treatment. Twenty-four hours after the final chelator injection, rats were killed and vanadium concentrations were determined in various tissues. Tiron and DFOA were effective compounds in mobilizing vanadium after NaVO3 administration, whereas Tiron was the most effective chelator after vanadyl sulphate administration. Ascorbic acid neither increased urinary elimination nor decreased tissue vanadium concentrations.

Topics: 1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt; Administration, Oral; Animals; Ascorbic Acid; Chelating Agents; Deferoxamine; Male; Rats; Rats, Inbred Strains; Thiomalates; Tissue Distribution; Vanadates; Vanadium; Vanadium Compounds

The nonenzymatic oxidation of NADH was studied spectrophotometrically in the presence of two vanadium compounds, sodium orthovanadate and vanadyl sulfate. At physiological pH 7.4, in 25 mM sodium phosphate buffer, addition of the synthetic thiol, dithioerythritol (DTE) results in a marked increase of NADH oxidation in the presence of sodium orthovanadate, but not in the presence of vanadyl sulfate. Other reductants, such as dithiothreitol and cysteine, can also increase NADH oxidation, whereas glutathione and ascorbate cannot. In all reactions, superoxide dismutase and catalase completely inhibit the vanadium-stimulated oxidation of NADH. Inhibition occurs in a concentration-dependent manner, and the boiled enzymes do not inhibit the thiol reaction. The hydroxyl radical scavenger, thiourea, inhibits the reaction, whereas urea cannot. ESR studies show that the ability of the thiol to reduce vanadate can be correlated with the degree of NADH oxidation. Using spin trapping techniques, hydroxyl radicals are detected during the course of the reaction. Addition of hydrogen peroxide to vanadyl in the presence of DTE greatly increases NADH oxidation; however, no NADH oxidation occurs when hydrogen peroxide is added to vanadyl and ascorbic acid. These results provide a partial explanation for the ability of vanadium compounds to both decrease cellular reducing equivalents and promote lipid peroxidation.

Topics: Ascorbic Acid; Dithioerythritol; Drug Synergism; Electron Spin Resonance Spectroscopy; Free Radicals; Hydrogen Peroxide; Hydroxylation; Kinetics; NAD; Oxidation-Reduction; Sulfhydryl Compounds; Superoxide Dismutase; Vanadates; Vanadium; Vanadium Compounds

Vanadium (V) as sodium orthovanadate induces an increase in lipid peroxidation in the kidneys after a single subcutaneous or intraperitoneal injection to rats or mice. The rate of malondialdehyde (MDA) formation, an index of lipid peroxidation, by kidney homogenates increased by more than 100% 1 h after injection. Chronic exposure of rats to vanadium sulfate, initially through maternal milk and later in the drinking water, resulted after 10 weeks in a significant increase in MDA formation by kidney but not by other tissues. In both acute and chronic studies in rats and mice, no significant increase in lipid peroxidation by V treatment was detected in brain, heart, lung, spleen, or liver. In mice, administration of ascorbate prior to acute exposure to V diminished both toxicity, i.e., respiratory depression and limb paralysis, and the formation of MDA in kidney.

Topics: Animals; Ascorbic Acid; Diet; Kidney; Lipid Peroxides; Male; Malondialdehyde; Mice; Mice, Inbred Strains; Rats; Rats, Inbred Strains; Time Factors; Vanadates; Vanadium; Vanadium Compounds