Comparative mutagenicity of 4-(carbethoxynitrosamino)-4-(3-pyridyl)butanal and 4-(carbethoxynitrosamino)-1-(3-pyridy1)-1-butanone, model compounds for {alpha}-hydroxylation of N'-nitrosonornicotine

4-(Carbethoxynitrosamino)-1-(3-pyridy1)butanal, a stable precursorto the putative diazohydroxide formed by 5'-hyd-roxylation ofthe tobacco-specific nitrosamine, N'-nitrosonornicotine, wassynthesized in six steps from nicotinaldehyde. Its mutagenicitytoward S. typhimurium was compared to that of 4-(carbethoxynitrosamino)-1-(3-pyridyl)-1-butanone,a precursor to the diazohydroxide formed by 2'-hydroxylationof N'-nitrosonornicotine. At equimolar doses, 4-(carbethoxy-nitrosamino)-1-(3-pyridy)-1-butanonewas a potent mutageon, but 4-(carbethoxynitrosamino)-1-(3-pyridy)butanal was inactive toward strains TA 100 and TA 1535. Theresults of this study indicate that the putative diazohydroxideformed by 2'-hydroxylation of N'-nitrosonornocotine has higherinherent mutagemicity toward S. typhimurinum than does the correspondingdiazohydroxide formed by 5'-hydroxylation.