Tryptophan pyrolysis products, Trp-P-1 and Trp-P-2 induce apoptosis in primary cultured rat hepatocytes

The cytotoxicity of heterocyclic amines, dietary carcinogens derived from c ooked foods, to primary cultured rat hepatocytes was studied. A tryptophan pyrolysis product, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) wa s the most cytotoxic of 11 compounds tested. Trp-P-l was found to induce ap optosis as measured by morphological changes in nuclear chromatin and inter nucleosomal DNA fragmentation. 3-Amino-1-methyl-5H-pyrido[4,3-b] indole (Tr p-P-2) showed a moderate apoptotic effect, and other compounds had a simila r but weaker effect.