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Issue 0, 1987
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Metabolites of Aspergillus ustus. Part 4. Stable-isotope labelling studies on the biosynthesis of the austalides

Abstract

Incorporationof [1-13C]-, [1,2-13C2]-and [1-13C,2,2,2-2H3]-acetate, and (3RS)-[2-13C]mevalonolactone into austalide D(2), a metabolite of Aspergillus ustus, shows that the austalides are derived from 6[(2E,6E)farnesyl]-5,7-dihydroxy-4-methylphthalide. The proposed mechanism for the subsequent cyclisation and oxidative modifications of the farnesyl moiety, consistent with the relative stereochemistry of the austalides and the structures of the cometabolites, austalides J (4), K (5), and L (6), is supported by the incorporation of austalide K into austalide D. The addition of ethanol to growing cultures of A. ustus severely inhibits normal metabolite production and induces the formation of a new metabolite, ethyl 6-ethyl-2,4-dihydroxy-3-methylbenzoate (11). The biosynthetic origin of this metabolite was studied using [1-13C]- and [1-13C,2,2,2-2H3]acetate and (2S)-[methyl-13C]methionine as precursors.

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Article type: Paper
DOI: 10.1039/P19870002253
J. Chem. Soc., Perkin Trans. 1, 1987, 2253-2257

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    Metabolites of Aspergillus ustus. Part 4. Stable-isotope labelling studies on the biosynthesis of the austalides

    A. E. de Jesus, R. M. Horak, P. S. Steyn and R. Vleggaar, J. Chem. Soc., Perkin Trans. 1, 1987, 2253
    DOI: 10.1039/P19870002253

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