Non-mutagenicity of 2-methyl-2,3-epoxybutane and factors influencing the mutagenicity of 2,3-epoxybutane.

The compound 2,3-epoxybutane (2,3-EB) is a direct mutagen for the base-pair-substitution-sensitive strains TA 1530, TA 1535 and TA 100, in the absence and in the presence of metabolic activation by liver S9-mix. Under the same experimental conditions, the 2-methyl derivative of 2,3-EB was not mutagenic, up to 10 mg per plate. The parent compound (2,3-EB) was more active on strain TA 1530 in the presence of liver S9-mix. This was observed at every epoxide concentration tested. The increase of mutagenicity depended on the S9 concentration, the mix composition and to a small extent on the method utilized.