Antimutagenic effect of amino acids on the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)

The antimutagenic activity of protein-constituting amino acids except histidine on the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was investigated in vitro using Salmonella typhinurium TA-100 as an indicator bacterium (Ames test), and concentrations (IC SUB50) of amino acids that inhibit 50% of the mutagenecity were measured. Cysteine was found to be most active and glycine, tryptophan, lysine, and argi-nine were strong antimutagenic amino acids. Other amino acids showed moderate or weak antimutagenic activities, depending on the amino acids. The results indicate that amino acids play a substantial role in chemoprevention of N-nitroso amine-induced mutagenicity.