Benzoxepine Esters as Precursors of the Wound‐Activated Chemical Defence of Mycena galopus

Abstract The native precursors E / Z ‐1a to E / Z ‐1e and 2a – 2e of the antifungally active benzoxepines E / Z ‐1 and 2 have been isolated from intact fruiting bodies of Mycena galopus . These precursors turned out to be fatty acid esters of the benzoxepines (pterulones) E / Z ‐1 and 2 . Metabolic profiling of ethyl acetate extracts from intact fruiting bodies, from the latex and from mechanically wounded fruiting bodies revealed that the known antifungally active benzoxepines E / Z ‐1 and the previously unknown benzoxepines 2 are only present in injured fruiting bodies. Intact fruiting bodies and the latex, however, exclusively contain the corresponding ester derivatives E / Z ‐1a to E / Z ‐1e and 2a – 2e . Unlike the antifungally active benzoxepines E / Z ‐1 and 2 , the esters E / Z ‐1a to E / Z ‐1e present in intact fruiting bodies turned out to be inactive. Upon injury the inactive esters E / Z ‐1a to E / Z ‐1e are cleaved by a putative esterase, and the bioactive benzoxepines E / Z ‐1 and 2 are released, suggesting a wound‐activated defence mechanism of M. galopus against yeasts and parasitic fungi. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)