chapter  7_1
17 Pages

Fate of Ingested Mutagens

More than 15 different mutagenic heterocyclic arylamines have been identified as products of heating food. These mutagens are in general indirectly acting; they require conversion into activated forms in order to become mutagenic to cells. Two of the metabolites are mutagenic to Salmonella typhimurium TA98 without addition of S9-mix. From the pyrolysates of phenylalanine and phenylalanine-containing mixtures, two heterocyclic arylamines are isolated as potent mutagens to S. typhimurium TA98. From the pyrolysates of protein-rich foods, two mutagenic aminoquinolines, IQ and MeIQ, have been isolated. Several mutagenic amino-N-methylimidazoles have been isolated from cooked foods. In Salmonella mutagenesis test, the capacities of S9-mix for activation are localized mainly in the microsomal fraction, as shown by studying subcellular fractions of rat liver homogenates. In a microsomal reaction, harman was metabolized into phenolic derivatives, but none of the metabolites had the comutagenic effect. The metabolites were identified as demethylated IQ, N-acetyl-IQ, and IQ sulfamate.