INHIBITION OF STEROL 14-ALPHA-DEMETHYLATION IN BOTRYTIS-CINEREA BY THE NOVEL IMIDAZOLE-1-CARBOXYLATE FUNGICIDES

The effect of the novel imidazole-1-carboxylates (1-(4-substituted phenoxymethyl)-2,2-dimethylpropyl imidazole-1-carboxylates), which have a carbonyl group linking to the 1-position of imidazole, on growth and sterol biosynthesis in Botrytis cinerea was studied. The present fungicidal compounds severely suppressed the mycelial growth of B. cinerea with a concomitant decrease in the ergosterol level and the accumulation of 14α-methyl sterols, indicating inhibition of sterol 14α-demethylase. The 14α-demethylation is well known to be catalyzed by cytochrome P450-dependent monooxygenase, which gives type II spectral changes by interacting with 14α-demethylation inhibitors such as prochloraz. Imidazole-1-carboxylates produced type II spectra with rat liver P450. These results demonstrate that the inhibition of 14α-demethylation is the mode of action of the present azole fungicides. © 1991.