Inhibition of Very-Long-Chain Fatty Acid Biosynthesis by 2-Chloro-N-(3-methoxy-2thenyl)-2,6-dimethylacetanilide, Thenylchlor, and Its Analogs

The herbicide thenylchlor and its analogs inhibited the incorporation of [1-14C]oleate and [214C]malonate into very-long-chain fatty acids (VLCFAs) in Scenedesmus cells and leek microsomes from Allium porrum, respectively. Although the precise mode of interaction of thenylchlor at the molecular level is not completely clarified by the present study, it is concluded that thenylchlor acts as an inhibitor of the elongase enzyme involved in biosynthesis of fatty acids with alkyl chains longer than C18. For a strong inhibition of VLCFA formation, an N,N-disubstituted amide moiety of chloroacetamides is required. Furthermore, 2,6dimethyl substituents at the benzene ring and electron-donating groups such as methoxyl or methyl at the 3 position of the thiophene ring produce a strong inhibition of VLCFA formation. A correlation was found between the phytotoxic effect against barnyardgrass (Echinochloa oryzicola) and the decreased VLCFA formation