phosphorus-radioisotopes and 2-amino-6-methyldipyrido(1-2-a-3--2--d)imidazole

When mutagens extracted from the urine of two smokers of black tobacco were reacted with DNA in vitro in the presence of a metabolic activation system, several DNA adducts were detected by 32P-postlabelling analysis. Some of these adducts were also visible, but only faintly, on the autoradiogram for a non-smoker's urine. DNA adducts produced in vitro by 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline or 2-amino-1-methyl-6-phenylimidazo[3,5-b]pyridine could not account for the adduct pattern produced by the urinary mutagens. However, three or four 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-related DNA adducts were present among the five or six adducts observed for smokers in the autoradiograms of urinary mutagen-adducted nucleotides. Mutagenicity testing combined with HPLC fractionation of urinary extracts also supported the postlabelling data which implicates PhIP as a mutagen in the urine of smokers of black tobacco.

Topics: Chromatography, High Pressure Liquid; Chromatography, Thin Layer; DNA; DNA Damage; Humans; Imidazoles; Mutagens; Nicotiana; Nucleotides; Phosphorus Radioisotopes; Plants, Toxic; Smoking

2-Amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-1) binds covalently to DNA after metabolic activation to give 2-(C8-guanyl)amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Gua-Glu-P-1). The importance of the intercalative ability of the Glu-P-1 skeleton into DNA base pairs for this reaction is emphasized. The reactive form of Glu-P-1, N-acetoxy-Glu-P-1 (N-OAc-Glu-P-1), reacts preferentially at the C8 position of guanine residues in G-C-rich regions of DNA.

Topics: Base Sequence; Carcinogens; DNA; Imidazoles; Intercalating Agents; Mutagenicity Tests; Mutagens; Mutation; Phosphorus Radioisotopes; Salmonella typhimurium; Structure-Activity Relationship