Mutagenicity studies of benzalazine

Benzalazine (2-hydroxy-5-[(4-carboxyphenyl) azo] benzoic acid, CAS 64896-26-0), a new agent for the treatment of ulcerative colitis and Crohn's disease of the large intestine, was studied for genotoxic effects by using the following short-term in vitro and in vivo test: 1. reverse mutation test (Ames method) on Salmonella typhimurium, 2. HGPRT (hypoxanthine-guanine phosphoribosyl transferase) point mutation test on V79 hamster cells, 3. in vivo cytogenetic test on Chinese hamster cells, and 4. in vivo sister chromatid exchange test on Chinese hamster cells. Benzalazine did not show any positive response in the reverse mutation test, HGPRT-point mutation test, in vivo cytogenetic and sister chromatid exchange test.