Decay kinetics of nicotine/NNK–DNA adducts in vivo studied by accelerator mass spectrometry

The decay kinetics of nicotine–DNA adducts and NNK–DNA adducts in mice liver after single dosing was studied by accelerator mass spectrometry (AMS). The decay is characterized by a two-stage process. The half-lives of nicotine–DNA adducts are 1.3 d (4–24 h) and 7.0 d (1–21 d), while for NNK–DNA adducts are 0.7 d (4–24 h) and 18.0 d (1–21 d). The relatively faster decay of nicotine–DNA adducts suggests that the genotoxicity of nicotine is weaker than that of NNK. The in vitro study shows that the metabolization of nicotine is necessary for the final formation of nicotine–DNA adducts, and nicotine Δ1′(5′) iminium ion is a probable metabolite species that binds to DNA molecule covalently.