Induction of 8-hydroxy-2′-deoxyguanosine in CHO-K1 cells exposed to phenyl-hydroquinone, a metabolite of ortho-phenylphenol

Abstract The induction of 8-hydroxy-2′-deoxyguanosine (8-OHdG), an index of oxidative DNA modification, was investigated in CHO-K1 cells exposed to phenyl-hydroquinone (PHQ), a major metabolite of ortho -phenylphenol (OPP), an antimicrobial. Addition of PHQ at a concentration of 50 μM to CHO cell suspensions (10 6 cells/ml) induced slight elevation of intracellular 8-OHdG levels. Pretreatment of CHO cells with 3-amino-l,2,4-triazole (AT, 20 mM) enhanced PHQ-induced 8-OHdG formation which was accompanied by cell death. Pretreatment of CHO-K1 cells with AT (20 mM) and deferoxamine (DeFe, 20 mM) inhibited the formation of 8-OHdG as well as cell death caused by PHQ. Neither AT nor DeFe affected cell viability or the formation of 8-OHdG in untreated CHO cells during the incubation period. The loss of cellular glutathione induced by the addition of PHQ alone was enhanced by the pretreatment of CHO cells with AT or AT plus DeFe. When PHQ was added to AT-pretreated cell suspensions, the concentration of PHQ decreased with time. This decease was accompanied by the formation of phenyl-benzoquinone (PBQ). These results suggest that the reactive oxygen species derived from autoxidation of PHQ which converts to PBQ via phenyl-semiquinone elicit DNA damage in CHO cells, especially when the activity of cellular catalase is inhibited.