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Absorption and Metabolism of 3-Hydroxy-5-methylisoxazole in Plants and the Biological Activites of its Metabolites. S. Kamimura, Group Manager, Fermentation Research Laboratories, Sankyo Co., Ltd., Hiromachi, Shinagawa-ku, Tokyo; M. Nishikawa(2), H. Saeki(3), and Y. Takahi(4). (2)Research Assistant, Fermentation Research Laboratories, Sankyo Co., Ltd., Hiromachi, Shinagawa-ku, Tokyo; (3)Chemist, Central Research Laboratories, Sankyo Co., Ltd., Hiromachi, Shinagawa-ku, Tokyo; (4)Assistant Group Manager, Agricultural Chemicals Research Laboratories, Sankyo Co., Ltd., Shiga, Japan. Phytopathology 64:1273-1281. Accepted for publication 9 April 1974. DOI: 10.1094/Phyto-64-1273.

The absorption and metabolism of the soil fungicide, 3-hydroxy-5-methylisoxazole (Tachigaren, Code No. F-319), by cucumber, tomato, and rice plants was investigated. Absorption of (3-14C)-F-319 into roots of these seedlings from nutrient solutions was rapid; translocation into leaves occurred 24 h after treatment, movement was readily traced from treated to untreated rootlets, which also exuded small amounts of the chemical. F-319 was converted into two major metabolites [MU: 3-(β-D-glucopyranosyloxy)-5-methylisoxazole; and ML: 2-(β-D-glucopyranosyl)-5-methyl-4-isoxazolin-3-one] in roots and shoots of the treated plants. MU and ML were isolated and purified as crystals by column chromatography, and their structure was determined by spectroscopic analyses of mass, nuclear magnetic resonance, infrared and ultraviolet spectra, optical rotatory dispersion curves, and acid hydrolysis. Synthesized samples were identical with the products of F-319 metabolism in plants. No phytotoxic effect of ML on cucumber and rice seedling growth was observed. MU retarded the growth of germinated rice seed when applied at the high concn of 1,500 µg/ml, as did F-319 at the same concn. However, MU exerted less of a suppressive effect on water uptake by rice seedlings than did F-319. Both F-319 and MU displayed toxic activity against Pythium debaryanum, but ML was inactive in this respect.

Additional keywords: hymexazol, distribution, glycosidation.