Carcinogenic activity of 3-amino-1-methyl-5H-pyrido [4,3-b]indole (Trp-P-2), a pyrolysis product of tryptophan.

The carcinogenic activity of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), a pyrolysis product of tryptophan, was studied in inbred strain ACI rats. Twenty rats received a diet containing 0.01% Trp-P-2 for 870 days. Nineteen rats survived for more than 400 days after the start of feeding, 1 rat developed a hemangioendothelial sarcoma of the liver, and 6 rats developed neoplastic liver nodules. These liver tumors were found only in female rats that died 666--870 days after the start of feeding. No liver tumors were found in control animals.