Three new metabolites, named macommelinal, macrophin and macrophic acid, were isolated from the culture broth of Macrophoma commelinae IFO 9570. Their structures were determined to be 2-(4-methoxy-6-methyl-2-oxo-2H-pyran-5-yl)ethanal, 3-methyl-2-butenoic acid (E)-[5-hydroxymethyl-4-methoxy-6-(2-methoxycarbonylethenyl)-2-oxo-2H-pyran-3-ly]methyl ester and 3-(4-methoxy-3,5-dimethyl-2-oxo-2H-pyran-6-yl)-2-propenoic acid, respectively. 4 Acetyl-3-methoxy-5-methylbenzoic acid, now named macrophomic acid, was also isolated from a large-scale culture.The biosynthesis of the macommelin group, novel 5-substituted 2-pyrone metabolites, has been investigated by feeding experiments with [1-^<13>C]-, [1,2-^<13>C_2]- and [1-^<13>C, 2-^2H_3]acetate and [2-^<13>C]malonate. It was concluded that all these metabolites originated from a single straight tetraketide chain. Furthermore, the biogenetic mutual relationships of these metabolites including potential intermediates were estabished through incorporation experiments with ^<14>C-labeled compounds.
Studies on Metabolites of Macrophoma commelinae. III. : Isolation of New Metabolites and Biosynthesis of Macommelin Group
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