Abstract
Fungicidal activity of triflumizole, (E)-4-chloro-α, α, α-trifluoro-N-(1-imidazol-1-yl-2-propoxyethylidene)-o-toluidine, and its analogs against cucumber powdery mildew was analyzed quantitatively by using their physicochemical structural parameters and regression analysis. The result showed that steric, electronic and hydrophobic effects of substituents on the benzene ring were important for the fungicidal activity. The effects of substituents on the imino carbon were expressed by steric and hydrophobic parameters as well as indicator variables for α, β-unsaturated and β-oxy structures. Conformational analyses and computer graphics were employed to study the mode of interaction of triflumizole with cytochrome P-450, the target enzyme of fungicidal azoles. An energy minimum structure of triflumizole was found to fit the cavity of cytochrome P-450 so as to block the oxidation of lanosterol, the ergosterol precursor. The result of regression analysis and the computer graphics model suggested that steric and hydrophobic properties of imidazole derivatives are important to inhibit the biosynthesis of ergosterol by antagonizing cytochrome P-450 oxidase.
