Detection of DNA lesions in cultured human fibroblasts induced by active oxygen species generated from a hydroxylated metabolite of 2-naphthylamine.

DNA lesions induced by active oxygen species generated from N-hydroxy-2-naphthylamine were detected by an alkaline elution technique using cultured normal human lung fibroblast cells. The lesions were detected dose-dependently when cells were treated with the carcinogen either at 0 degrees or at 20 degrees. Their formation was strongly dependent on pH and increased with alkalinity up to pH 8.2 in parallel with the formation of hydrogen peroxide. Inhibition was observed by catalase, superoxide dismutase, and benzoic acid which is a typical hydroxyl radical scavenger. Other hydroxyl radical scavengers, mannitol and ethanol, were only effective when a cell-free in vitro reaction system was used, followed by alkaline elution. These results imply first that hydrogen peroxide and superoxide anion radicals generated during the conversion of N-hydroxy-2-naphthylamine to nitroxide radical are involved in the formation of DNA lesions and second that hydroxyl radical produced by an intra-cellular metal ion-catalyzed reaction might finally react with DNA bases and the DNA backbone.