Effects of antioxidants on quercetin-induced nuclear DNA damage and lipid peroxidation.

The effects of catalase, superoxide dismutase, mannitol, glutathione, and diallyl sulfide on quercetin-induced DNA damage and lipid peroxidation were investigated in a model system of isolated rat-liver nuclei under aerobic conditions and in the presence of equimolar iron or copper. Mannitol produced a small but significant inhibition of the concurrent nuclear DNA damage and lipid peroxidation induced by quercetin in the presence of iron or copper. Catalase significantly decreased quercetin-induced nuclear DNA damage only in the presence of iron and had no significant effect on lipid peroxidation. Superoxide dismutase showed no significant effect on nuclear DNA damage, but stimulated the quercetin-induced lipid peroxidation only in the presence of copper. Glutathione significantly inhibited the nuclear lipid peroxidation but enhanced the DNA damage. Diallyl sulfide significantly enhanced the nuclear DNA damage but stimulated the lipid peroxidation only in the presence of iron. These results suggest that the reactive oxygen species, especially the hydroxyl radicals, are responsible for the concurrent lipid peroxidation and DNA damage induced by quercetin in the presence of iron or copper in isolated rat-liver nuclei.