Epicoccalone, a Coumarin‐Type Chymotrypsin Inhibitor, and Isobenzofuran Congeners from an Epicoccum sp. Associated with a Tree Fungus

The bioactivity‐guided fractionation of metabolites from an Epicoccum sp. isolated from the fruiting body of the tree fungus Pholiota squarrosa led to the discovery of a new inhibitor of the serine protease α‐chymotrypsin. The structure of the active compound, epicoccalone (1), was fully elucidated by spectrometric and spectroscopic methods, revealing a coumarin ring system with an unprecedented substitution pattern. Two isobenzofuran‐derived co‐metabolites were identified that are remarkably similar to the epicoccalone coumarin core, strongly suggesting that these metabolites share the same orsellinic acid like polyketide pathway.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)