Oxidative damage of DNA and benzoate by chelated and non-chelated copper in presence of hydrogen peroxide.

Benzoate hydroxylation test revealed that Cu(II) reacting with H2O2 produced OH degree radicals, which nicked or damaged DNA or hydroxylated benzoate, the extent of damage or hydroxylation depending on the period of incubation. The production of OH degree free radicals was also supported by the scavenger studies. Neither Cu(II) nor H2O2 alone could damage DNA or hydroxylate benzoate. EDTA-chelated Cu(II) plus H2O2 could damage DNA or hydroxylate benzoate only in presence of the biological reductant, L-cysteine, the damage increased with the increasing molar ratio of L-cysteine to Cu-EDTA. The biological relevance of the EDTA chelated Cu(II) and H2O2 system is discussed.