Comutagenic effect of norharman with aminopyridine derivatives.

The mutagenicities of 3 monoaminopyridines, 4 methyl-substituted monoaminopyridines and 3 diaminopyridines were tested with or without norharman in the Salmonella assay system. None of the compounds was mutagenic without norharman. However, 3-aminopyridine and 2-amino-3-methylpyridine were mutagenic in the presence of norharman and S9 mix; 3-aminopyridine was mutagenic to TA98, but not to TA100, while 2-amino-3-methylpyridine was mutagenic to both TA98 and TA100, although its mutagenicity was much stronger in TA98.