Structure activity studies with N-nitrosamines using Salmonella typhimurium and Escherichia coli

Mutagenic activities of a large number of nitrosamines were determined using Salmonella histidine reversion and Escherichia coli arginine reversion assays. The cyclic nitrosamines exhibited a close correlation between their mutagenic and carcinogenic properties, while no such relationship was evident with the aliphatic nitrosamines. Substitution of cyclic nitrosamines with methyl, hydroxy and oxy groups did not alter the mutagenic activities. However, when positions alpha to the N-nitroso groups were substituted with methyl groups, the biological activity was eliminated. Substitution with halogens enhanced, whereas carboxyl substitution eliminated the biological activity. The E. coli assay not only substantiated the observations made with Salmonella, but also demonstrated mutagenic activity in the case of certain carcinogenic nitrosamines which were not mutagenic in the Salmonella assay.