Nutritional toxicology: on the mechanisms of inhibition of formation of potent carcinogens during cooking.

Frying or broiling of meat or fish yields powerful genotoxic carcinogens such as 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and related amino-imidazo azaarene carcinogens. We have explored the mode of formation and inhibition of production of these carcinogens. Maillard reactions from precursor amino acids, hydroxyamino acids, and simple carbohydrates appear to yield reactive aldehydes that interact with creatinine to produce specific mutagens/carcinogens. The simplest such IQ-like mutagen, 2-amino-5-ethylidene-1-methylimidazol-4-one, was prepared from acetaldehyde and creatinine. The formation of mutagens in laboratory models and during realistic frying of meat was effectively blocked by L-tryptophan, L-proline, and mixtures thereof. The underlying mechanism rests on competition, between the inhibitors containing an indole ring and creatinine, for intermediary reactive aldehydes produced during Maillard type reactions. The inhibition by L-tryptophan, L-proline, and other indoles is effective and can also be implemented practically.