Tomoki Hoshi, Kazuhiro, Yamada, Shinichi Fuji, Hiromitus Furuya, Yuko, Yoshizawa and Keimei Oh
Keywords: Magnaporthe oryzae, riazole derivatives, brassinsoteroid biosynthesis inhibitors, fungicide, rice blast disease
Abstract: Rice blast disease (RBD) is one of the most devastating diseases of cultivated rice caused by the pathogenic fungi Magnaporthe oryzae. To explore new compounds with antifungal activity against Magnaporthe oryzae, a select group of compounds synthesized in our laboratory targeting CYP90D1, a key enzyme in brassinosteroid biosynthesis, has been evaluated. The antifungal activity of the test compounds against Magnaporthe oryzae was determined by using in vitro mycelial growth inhibition tests. Structure-activity relationship analysis indicated that introducing a double bone to the alkyloxy substituent at the position 2 of phenoxy moiety of this synthetic series enhanced the antifungal activity. Moreover, a bulkyl substituent at the alkyloxy moiety exhibited a negative effect on promoting the antifungal activity. Among the 11 test compounds, we found that 2RS, 4RS-1-[4-chlorophenyl-(2-methylphenoxy)-ethyl]-1,3-dioxolan-2-yl-methyl]-1H-1,2,4-triazole (7h) displayed potent antifungal activity against Magnaporthe oryzae with an IC50 value approximately 23.3±0.5 ?M
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