Structure activity studies with n-nitrosamines using Salmonella typhimurium and escherichia coli

Cyclic nitrosamines exhibited a relationship between their mutagenic activity and molecular ring size. They exhibited a closer relationship between their mutagenic and carcinogenic properties. Substitution with alkyl or hydroxy groups did not affect the biological activity. Substitution in the ..cap alpha..-positions to the N-nitroso group eliminated both mutagenic and carcinogenic properties. Halogen substitution enhanced carcinogenic activity and had slight if any effect on mutagenicity. Carboxy substitution eliminated the biological activity. Aliphatic nitrosamines failed to show any relationship between mutagenesis and carcinogenesis. Use of E. coli assay not only substantiated Salmonella results; it was also capable of identifying certain carcinogens (nitrosopyrroline, 3,4-dibromonitrosopyrrolidine and methylethylnitrosamine) as mutagens that were missed in the Salmonella assay.