Mutagenicity of 1,2-dimethylhydrazine towards Salmonella typhimurium, co-mutagenic effect of secondary biliary acids.

Even though 1,2-dimethylhydrazine (DMH) is highly carcinogenic in experimental animals, it has not been shown to be clearly mutagenic in any of the short term tests in vitro. The present report demonstrates that DMH is mutagenic in the Ames test when it is incubated together with lithocholic or deoxycholic acid with or without metabolic activation. Such a co-mutagenic effect seems to be restricted to the secondary biliary acids since neither cholic nor chenodeoxycholic acid had the same activity. The secondary biliary acids are present in the colon where they are formed by bacteria. Such a co-mutagenic effect could thus be of importance with regard to the carcinogenic activity of DMH. It could also be relevant to colon carcinogenesis in humans.