Organic solvents inhibit the mutagenicity of promutagens dimethylnitrosamine and methylbutylnitrosamine in a higher plant Arabidopsis thaliana.

The organic solvents dimethylsulphoxide (DMSO), acetone, ethanol and dimethylformamide inhibited the mutagenic activity of the promutagens dimethylnitrosamine and methylbutylnitrosamine in a higher plant Arabidopsis thaliana. In contrast, the direct-acting mutagens N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and N-methyl-N-nitrosourea (MNU) were not affected by the organic solvents (with the exception of DMSO). The effect of DMSO on MNNG- and MNU-mutagenesis is explained by its effect on the pH of the mutagenic solution. The results support the assumption that the activation of promutagenic nitrosamines in A. thaliana proceeds by the same, or similar, mechanisms to that in 'animal' activation.