Induction of chromosome loss in Saccharomyces cerevisiae strain D61.M by selected benzimidazole compounds.

Twenty-two benzimidazole compounds were tested for induction of chromosome loss (CHRL) in the diploid yeast Saccharomyces cerevisiae strain D61.M. Six compounds tested positive for CHRL induction: mebendazole, albendazole, RS-9237-000, fenbendazole, 2-benzimidazolylacetonitrile, and thiabendazole. Mebendazole, albendazole, RS-9237-000, and fenbendazole were strongly positive only after modified testing media were used to enhance solubility. The compounds that tested negative for CHRL were 2-phenylbenzimidazole, 2-(2-pyridyl)benzimidazole, benzimidazole, 2-aminobenzimidazole, 2-amino-5,6-dimethylbenzimidazole, 2-(aminomethyl)benzimidazole dihydrochloride hydrate, 5,6-dimethylbenzimidazole, 2-guanidinobenzimidazole, 2-methylbenzimidazole, 2-(methylmercapto) benzimidazole, 1-methyl-2-phenylbenzimidazole, 2-benzimidazolylurea, RS-65255-000, oxibendazole, and RS-95005-000. One chemical, cambendazole, tested negative or only marginally positive. Modified testing medium was also used to enhance the solubility of 2-phenylbenzimidazole, oxibendazole, and RS-95005-000. Because no toxicity was observed with oxibendazole or RS-95005-000, the negative results obtained with these two compounds could not be considered definitive.