Chemistry and mutagenicity of alpha-hydroxy nitrosamines

N-Nitroso-N-(hydroxymethyl)alkylamines, which are key intermediates in the metabolic activation of nitrosamines having a methyl group, were synthesized and their chemical and mutagenic properties were examined. Six N-nitroso-N-(hydroxymethyl)alkylamines (alkyl = methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl) were prepared by the deoxygenation of N-nitroso-N-(hydroperoxymethyl)alkylamines. Their stability in aqueous solution was highly dependent on pH, being stable in acidic media, but unstable in neutral or alkaline media. The structure also exerted a profound effect on the stability. Thus a branched alkyl group accelerated the decomposition, although compounds with a normal alkyl group showed a similar response to the change of pH. The alkylating activity of the compounds toward deoxyguanosine and thymidine was demonstrated, and was dependent on the reaction solvent used. The overall alkylating activity was found to be highest with the compound ultimately yielding a methylating agent, while a more selective alkylation towards the oxygen, compared to the nitrogen, was observed with the ethylating, propylating and butylating species. Reactions with cysteine and histidine were also observed. A potent mutagenic effect of the N-nitroso-N-(hydroxymethyl)alkylamines was demonstrated in Salmonella typhimurium TA1535 and Escherichia coli WP2 and WP2 hcr-, in the absence of the S9 mix. A good correlation of the activities of the N-nitroso-N-dialkylamines and the N-nitroso-N-(hydroxymethyl)alkylamines with the same alkyl group was demonstrated.