Mutagenicity of Af-Nitroso Bile Acid Conjugates in Salmonella typhimurium and Diploid Human Lymphoblasts1

Two A/-nitroso bile acid conjugates, A/-nitrosotaurocholic acid and /V-nitrosoglycocholic acid, were tested for mutagenicity by forward mutation assay in Salmonella typhimurium TM 677 and in diploid human lymphoblasts, line TK6. /V-Nitrosoglycocholic acid and A/-nitrosotaurocholic acid showed similar concentra tion-response curves in the bacterial assay with statistically significant mutant fractions observed at about 0.12 mw. Nonnitrosated parent compounds were nonmutagenic. However, in the human cell assay, A/-nitrosotaurocholic acid gave statisti cally significant mutant fractions only at 0.4 rriM, but W-nitrosoglycocholic acid was mutagenic at 0.05 /IM, some 9000 times more potent. Experiments with quantitative Ames' S. typhimurium reversion assays indicated mutagenesis via base substitution.