Metabolism of Thiophanate-methyl by Pathogenic Fungi and Antifungal Activity of its Metabolites

Thiophanate-methyl (Th-M) was metabolized by Pellicularia sasakii and Alternaria mali which have some difference in sensitivity to this fungicide, and its main metabolite was identified as methyl 2-benzimidazolecarbamate (MBC). As minor metabolites, methyl 5-hydroxy-2-benzimidazolecarbamate (HMBC) and an unknown substance (X) were also found in the incubated solution. The similar metabolic products of Th-M were obtained by the fungi, with the exception of X which was formed only by a sensitive fungus, P. sasakii. However, the formation of MBC and HMBC by an insensitive fungus, A. mali was more rapid than those by P. sasakii. The antifungal activity of MBC against P. sasakii was more effective than that of Th-M or HMBC. Mycelial growth of A. mali was scarcely inhibited by MBC and HMBC.