Mutagenicity of five cyclic N-nitrosamines: assay with Salmonella typhimurium.

The mutagenicity of five cyclic N-nitrosamines was studied with the use of Salmonella typhimurium TA1535 in vitro with and without microsomal activation. The carcinogens nitrosopiperidine and nitrosopyrrolidine required metabolic activation before manifesting mutagenic activity. Nitrosoproline and nitrosohydroxyproline, noncarcinogens, were not mutagenic. Nitroso-3-pyrrolidinol was mutagenic in the absence of microsomes, thereby suggesting a role of hydroxylation in the metabolic activation of nitrosopyrrolidine to an ultimate carcinogenic species.