Covalent binding to DNA in vitro of 2',3'-oxides derived from allylbenzene analogs

Epoxidation at the allylic side chain is a major metabolic pathway for allylbenzene and its naturally occurring analogs safrole, estragole, and eugenol. We demonstrate herein that the epoxide metabolites of allylbenzene, estragole, and safrole can form covalent adducts with DNA in vitro, binding primarily to guanine, but also to the other three DNA bases. Epoxide hydrolases can prevent the binding of allylbenzene 2',3'-oxide to DNA in vitro. Four distinct adducts were detected by analytical TLC after the reaction of 2'-deoxyguanosine with allylbenzene 2',3'-oxide. One unstable adduct was formed rapidly, but gradually disappeared, whereas the other three adducts were formed more slowly but persisted. The major persistent adduct, which was isolated by preparative chromatography, was examined by MS and NMR. The structure of this adduct is 3'-N1-deoxyguanosyl-(2'-hydroxypropylbenzene). In addition, a generally applicable paradigm for the identification of deoxyguanosine or guanosine adducts by 13C and 1H NMR spectroscopy is presented.