Carcinogenicity in rats of a mutagenic compound, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole, from tryptophan pyrolysate

3-Amino-1,4-dimethyl-5H-pyrido4,3-b]indole (Trp-P-1) is a mutagenic principle isolated from a tryptophan pyrolysate. When Trp-P-1 was given to male and female F344 rats at concentrations of 0.015% and 0.02%, respectively, in the diet, it induced hepatocellular carcinomas in high incidence within a year. No tumor was found in control rats.