Mutagenicity of some indoles and related compounds in the Ames test

A series of indole derivatives and some analogues were tested for mutagenic activity using a histidine-requiring mutant of Salmonella typhimurium (TA 98). Quantitative tests were performed with and without addition of a liver fraction (S-9) from rats induced with Aroclor 1254. Three compounds, 2,3-dimethylindole, 2,3,5-trimethylindole and 2,3,6-trimethylindole, showed a mutagenic effect which was not increased on metabolic activation. The influence on the mutagenic activity of the number and positions of the substituents attached to the indole skeleton is discussed.