Identification of carcinogenic tryptophan pyrolysis products in human bile by high-performance liquid chromatography.

The carcinogenic tryptophan pyrolysis products 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) have been demonstrated to be present in human bile through use of a high-performance liquid chromatography (HPLC) method. The method consists of the acid-induced release of the carcinogens from bile components and their extraction with methylene chloride and subsequent quantification by HPLC. In seven subjects who had received catheterization of the bile duct and external biliarydrainage, the average amounts of Trp-P-1 and Trp-P-2 excreted daily in the bile were 408 fmol/day (n = 7) and 864 fmol/day (n = 7), respectively. In one subject, furthermore, significant daily changes of these carcinogen levels in bile and plasma were confirmed during 2 weeks of observation. These results indicate that one of the excretory pathways of these carcinogens is via bile. Our data also may suggest that Trp-P-1 and Trp-P-2 are derived from everyday foods.