| Abstract: | Pyrifenox, a new pyridine derivative, proved to be an inhibitor of ergosterol biosynthesis, blocking the pathway at the C-14 demethylation step in Ustilago maydis (CD.) Cor da. In treated sporidia the incorporation of 1-14C]acetic acid into ergosterol and squalene was reduced and the incorporation into sterols which retain the C-14 methyl group, mainly 24-methylenedihydrolanosterol and obtusifoliol, was increased. In addition, treatment with pyrifenox markedly reduced the incorporation into sterol esters. It is possible that the methylated sterols may be unsuitable substrates for the esterification enzyme. |
