Inhibitory effect of saturated fatty acids on the mutagenicity of N-nitrosodimethylamine.

Saturated fatty acids, C5-C12, inhibited the mutagenic activity of N-nitrosodimethylamine (NDMA) in E. coli WP2 uvrA/pKM101. The inhibition by laurate (C12) was due to the suppression of the enzymatic demethylation of NDMA, whereas that by caprate (C10) was simply due to the bactericidal effect of the fatty acid. Caproate (C6) did not affect the NDMA-demethylase, and evidence is presented to show that the inhibition of mutagenesis by caproate was a result of its interference with the uptake of NDMA metabolites into bacterial cells. Possible biological significance of the inhibition is discussed.