メチルカーバメート系殺虫剤の低毒化に関する合成・代謝研究

抄録

A number of aminosulfenyl, sulfinyl and alkoxysulfenyl derivatives of methylcarbamate insecticide were synthesized by appropriate substitution of the proton on the carbamyl nitrogen atom, and their insecticidal activity and toxicity to mice were examined. The toxicological properties of the original methylcarbamate were markedly affected by derivatization, resulting generally in substantial improvement in mammalian toxicity and retention or improvement in insecticidal activity. Some of the derivatives demonstrated greater residual effectiveness, and were less phytotoxic to crops. Metabolism of two carbofuran derivatives, i. e., benfuracarb and carbosulfan, in use or under development was examined. In plants and houseflies, both derivatized carbamates were metabolized mainly to carbofuran and related oxidation products, while degradation to phenolic products was the principal route of metabolism in rats. The results indicate that the selective toxicity of the derivative between insects and mammals is attributable to different pathways of metabolism. Studies on the behavior of carbosulfan in different environments showed that carbosulfan dissolved in the solvent containing various acids was transformed into the same alteration products, giving carbofuran, polysulfide derivatives of carbosulfan and biscarbofuran polysulfides as major products. Most of the polysulfide derivatives showed good insecticidal activity and all of them were less toxic to mice than carbofuran. These polysulfide derivatives were also formed in the rat stomach following oral administration of carbosulfan, indicating the contribution of the polysulfide derivatives to lower mammalian toxicity of carbosulfan. In virtually all of the derivatives were less effective inhibitors of acetylcholinesterase than the parent carbamates.