Mutagenicity of streptozotocin and several other nitrosourea compounds in Salmonella typhimurium.

The following nitrosourea compounds were compared for their ability to induce mutation (to histidine independence) in the histidine-requiring auxotroph Salmonella typhimurium his G46: MNU, streptozotocin (SZ, streptozocin) and its analogs SZA1 and SZA2, and the antitumor drugs BCNU, CCNU and DCNU. At equitoxic doses SZ, SZA1, SZA2 and MNU were almost equally mutagenic causing 150, 42, 140 and 170 mutants/106 survivors at 20% lethal dose (ID20) ALTHOUGH, ON A WIEGHT BASIS, SZ was the most mutagenic of all the compounds tested. At ID20 BCNU, CCNU and DCNU gave about 0.5 mutants/106 survivors. Our results show that these nitrosoureas, in common with many other drugs (such as cyclophosphamide, daunomycin, etc.) used in cancer chemotherapy, are highly mutagenic. The implication of our results in the screening of drugs for their mutagenicity to man is discussed.