Bioactive polyketide derivatives from the endophytic fungus Phaeosphaeriopsis musa

Two undescribed phenolic derivatives musaones A and B, six undescribed γ-butyrolactone musaolides A-F, together with two undescribed cyclopentanone musaolides G and H were isolated from the solid culture of an endophytic strain Phaeosphaeriopsis musae M. Arzanlou & Crous (Phaeosphaeriaceae). Their structures were unambiguously elucidated by extensive spectral analyses. The absolute configurations of two diastereomers musaolides G and H were assigned by comparing their experimental and calculated ECD data. Moreover, the in vitro α-glucosidase inhibition and cytotoxic activities of isolated compounds (except musaolide D) were evaluated to understand their biological effects, wherein musaone B and musaolide F displayed promising α-glucosidase inhibition with IC₅₀ values of 37.3 ± 0.59 μM and 105.18 ± 2.76 μM respectively, compared to the positive control acarbose (24.99 ± 1.28 μM).