Mutagenicity testing of steroids obtained from bile acids and cholesterol.

Twenty bile acid or cholesterol derivatives were tested for mutagenicity by the Ames spot test procedure against five Salmonella typhimurium strains in the presence and absence of rat liver microsomes. No strong mutagens were identified, but four of the compounds increased the number of revertant colonies observed. Three of these compounds were selected for dose response experiments using the Ames plate incorporation assay procedure with strain TA 1538. No positive results were obtained. These results suggest that none of the twenty bile acid derivatives tested is likely to be the initiating agent in the aetiology of colon cancer.