Polyoxygenated Cyclohexenoids with Promising α‑Glycosidase Inhibitory Activity Produced by <i>Phomopsis</i> sp. YE3250, an Endophytic Fungus Derived from Paeonia delavayi

Seven
new polyoxygenated cyclohexenoids, namely, phomopoxides A–G
(1–7), were isolated from the fermentation
broth extract of an endophytic fungal strain Phomopsis sp. YE3250 from the medicinal plant Paeonia delavayi Franch. The structures of these compounds were established by spectroscopic
interpretation. The absolute configurations of compounds 1 and 4 were confirmed by X-ray crystallographic analysis
and chemical derivative approach. All isolated compounds showed weak
cytotoxic activities toward three human tumor cell lines (Hela, MCF-7,
and NCI-H460) and weak antifungal activities against five pathogenic
fungi (Candida albicans, Aspergillus niger, Pyricularia oryzae, Fusarium avenaceum, and Hormodendrum compactum). In addition, compounds 1–7 showed a promising α-glycosidase
inhibitory activity with IC50 values of 1.47, 1.55, 1.83,
2.76, 2.88, 3.16, and 2.94 mM, respectively, as compared with a positive
control of acarbose (IC50 = 1.22 mM).