[Mechanism of methylation of DNA bases by symmetrical dimethylhydrazine]

The effect of disulfiram on the alkylation of purine bases of the liver and colon DNA in rats exposed to 1,2-dimethyl-hydrazine-3H has been studied. The pretreatment of rats with disulfiram which inhibits the DMH N-oxydation was found to prevent the methylation of guanine with DMH. However, the radioactivity was readily incorporated into normal (non-methylated) purine bases during synthesis. The lack of DNA methylation in animals pretreated with disulfiram indicated carbonium ion rather than methyl radical to alkylate DNA.