The major identified benzo[o]pyrene (BP)-DNA adduct formed by cytochrome P-450 contains BP bound at the C-6 position to the N-7 position of guanine (BP-N7Gua). This adduct is rapidly depurinated from DNA. When rats were treated with [14C]BP, about 0.02% of the administered dose of BP was excreted as BP-N7Gua in feces and urine within 5 days. Chloroform extracts of the urine and feces were analyzed by high-pressure liquid chromatography. The structure of the adduct was established by cochromatography with electrochemically prepared BP-N7Gua and by fluorescence line narrowing spectrometry. This study represents the first demonstration that BP-N7Gua is formed in vivo in animals treated with BP.
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