Formation of mutagenic activity from amino acids heated at cooking temperatures

To investigate the formation of aromatic amine-like mutagenic activity in cooked grain foods, amino acids were heated alone or in binary combinations at either 150 or 210°C. About half of the binary mixtures of arginine heated with other amino acids produced potent mutagenic responses in the Ames/Salmonella assay, but only cysteine produced mutagenic products when heated alone. One-to-one molar ratios of arginine heated with threonine, valine, cystine, cysteine or tryptophan produced reaction products that gave 1200–3200 revertants/mmol in Salmonella strain TA98 with metabolic activation. 1-Methylguanidine, a fragment of arginine, produced a mutagenic response when heated alone or in binary mixtures with all amino acids tested. Analysis of reaction product extracts by solid-phase extraction and HPLC failed to find the known heterocyclic amines commonly found in cooked meats that would explain the measured mutagenic activity. As judged by biological and chemical characterization, several new aromatic amine mutagens are formed by heating some simple amino acids combined with arginine, and these reactants may be the source of the mutagenic products detected in the extracts of some cooked grain-based foods.