Characterization of aminoindamines and aminoindoanilines formed by oxidative hair dyeing and their mutagenicity.

2-Amino-5-methoxy-2'(or 3')-methylindamine and 2-amino-5-methoxy-2'(or 3')-methylindoaniline were isolated from a coloring matter formed by oxidative condensation of 2,5-diaminotoluene with 2,4-diaminoanisole, and their structures were elucidated on the basis of nuclear magnetic resonance and mass spectral data. These two main components of the oxidation product formed at the early stage exhibited a positive result in the mutagenicity test on the thin-layer chromatography plate. The mutagenic activities of purified aminoindamines and aminoindoanilines against Salmonella typhimurium TA 98 were as strong as that of 2-acetamidofluorene. It was also demonstrated that 5-methoxy-2'(or 3')-methylindamine was formed in 10% yield under the conditions used for hair dyeing and the yield was dependent upon the molar ratio of 2,5-diaminotoluene to 2,4-diaminoanisole.