Comparison of the Fungicidal Effects of Thiabendazole and Its 1-Alkyl Derivatives

As a part of a study of the structure-activity relationship of thiabendazole (TBZ), the inhibitory effects of TBZ and 1-alkyl-TBZs (1-methyl-TBZ, 1-ethyl-TBZ, 1-propyl-TBZ and 1-butyl-TBZ) on the growth of nine species of food-borne fungi were examined.TBZ was shown to have remarkable antifungal activity, but when the 1-position of TBZ was substituted with an alkyl group (methyl, ethyl, propyl or butyl), the inhibitory effects significantly decreased in the order of 1-butyl-TBZ, 1-propyl-TBZ, 1-ethyl-TBZ and 1-methyl-TBZ. In particular, 1-methyl-TBZ did not show any inhibitory effect on any of the tested fungi even at the concentration of 1, 000μg/ml. Thus, the antifungal activity of TBZ is affected remarkably by a substituent group at the 1-position in the structure.