Copper-mediated oxidative DNA damage induced by eugenol: possible involvement of O-demethylation

Abstract Eugenol used as a flavor has potential carcinogenicity. DNA adduct formation via 2,3-epoxidation pathway has been thought to be a major mechanism of DNA damage by carcinogenic allylbenzene analogs including eugenol. We examined whether eugenol can induce oxidative DNA damage in the presence of cytochrome P450 using [ 32 P]-5′-end-labeled DNA fragments obtained from human genes relevant to cancer. Eugenol induced Cu(II)-mediated DNA damage in the presence of cytochrome P450 (CYP)1A1, 1A2, 2C9, 2D6, or 2E1. CYP2D6 mediated eugenol-dependent DNA damage most efficiently. Piperidine and formamidopyrimidine-DNA glycosylase treatment induced cleavage sites mainly at T and G residues of the 5′-TG-3′ sequence, respectively. Interestingly, CYP2D6-treated eugenol strongly damaged C and G of the 5′-ACG-3′ sequence complementary to codon 273 of the p53 gene. These results suggest that CYP2D6-treated eugenol can cause double base lesions. DNA damage was inhibited by both catalase and bathocuproine, suggesting that H 2 O 2 and Cu(I) are involved. These results suggest that Cu(I)–hydroperoxo complex is primary reactive species causing DNA damage. Formation of 8-oxo-7,8-dihydro-2′-deoxyguanosine was significantly increased by CYP2D6-treated eugenol in the presence of Cu(II). Time-of-flight-mass spectrometry demonstrated that CYP2D6 catalyzed O -demethylation of eugenol to produce hydroxychavicol, capable of causing DNA damage. Therefore, it is concluded that eugenol may express carcinogenicity through oxidative DNA damage by its metabolite.