A new sesterterpenoid with β-glucuronidase inhibitory activity from the Cordyceps-colonising fungus Aspergillus versicolour 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 beta-glucuronidase inhibitory activity (IC50 = 49.82 +/- 1.21 mu M) with D-saccharicacid 1,4-lactone (IC50 = 57.35 +/- 0.78 mu M).