A new sesterterpenoid with <i>β</i>-glucuronidase inhibitory activity from the <i>Cordyceps</i>-colonising fungus <i>Aspergillus versicolour</i> ZJUTE2

A new sesterterpenoid versicolorin A (1) and five known compounds 2–6 were isolated from a Cordyceps-colonising fungus Aspergillus versicolour ZJUTE2 cultured on soybean meal. The planar structure of 1 was determined by 1D, 2D NMR and HR-ESI-MS. The stereochemistry of 1 was established by NOESY experiment, quantum chemical calculation of 13C NMR combined with DP4+ probability analysis, and comparison of the optical rotations. Compound 1 exhibited comparable in vitro β-glucuronidase inhibitory activity (IC50 = 49.82 ± 1.21 µM) with D-saccharicacid 1,4-lactone (IC50 = 57.35 ± 0.78 µM).