Effect of metal ions and xenobiotics on endogenous oxidation of DNA

The level in urine of 8-hydroxy-2'-deoxyguanosine (8-oxodG) is the standard biochemical marker of endogenous oxidation of DNA in humans and animals. A new method for assay of 8-oxodG in mouse and rat urine was developed. A modified method for solid phase extraction of this substance was developed. The baseline levels of 8-oxodG and 8-oxoG was measured in control rats and the effects of various compounds added to the diet or removed from the diet were assessed. The contribution of iron and copper ions to endogenous oxidation of DNA is close to 50%. Among the tested microelements (Zn, Cr, Se), the effect of selenium was the highest and depended on the duration of the selenium-deficient diet. Carcinogens including 20-methylcholanthrene and caffeic acid and a substituted quinone significantly enhanced guanine oxidation of rat DNA.