Comparison of the mutagenicities of malondialdehyde and the side products formed during its chemical synthesis.

Malondialdehyde, a product of polyunsaturated fatty acid metabolism and degradation, has been reported to be mutagenic and carcinogenic. The malondialdehyde used for testing was generated by the acidic hydrolysis of tetraalkoxypropanes. We have studied the production of compounds mutagenic to Salmonella typhimurium strain his D 3052 following the hydrolysis of tetraalkoxypropanes. The major mutagenic compound produced from tetraethoxypropane is beta-ethoxy-acrolein (90 to 100 revertants/mumol) and not malondialdehyde (3 to 5 revertants/mumol). Hydrolysis of tetramethoxypropane produces two compounds, beta-methoxy-acrolein (125 to 160 revertants/mumol) and 3,3-dimethoxypropionaldehyde (105 to 135 revertants/mumol), which are more mutagenic than is malondialdehyde. Using standard conditions for the hydrolysis of tetraethoxypropane, the yield of malondialdehyde is 25%, and the yield of beta-ethoxyacrolein is 13%. Considering the differences in specific mutagenicity, the compound which accounts for the bulk of the mutagenicity of a crude hydrolsate of tetraethoxypropane is not malondialdehyde. The presence of these incomplete hydrolysis products may lead to a substantial overestimation of the actual mutagenicity and carcinogenicity of malondialdehyde.