Bioactive 2-pyrone metabolites from an endophytic Phomopsis asparagi SWUKJ5.2020 of Kadsura angustifolia

Five new 2-pyrone metabolites, phomaspyrones A–E (1–5) along with three known compounds, macommelin-8,9-diol (6), macommelin-9-ol (7), and macommelin (8), were isolated from the culture broth of an endophytic fungus Phomopsis asparagi SWUKJ5.2020 of medicinal plant Kadsura angustifolia by sequentially purification over silica gel, Sephadex LH-20 column chromatography and preparative HPLC. Their structures were elucidated on the basis of spectroscopic analysis, including two-dimensional (2D) NMR and HRMS (ESI-TOF) data. Among them, compounds 3–5 exhibited notable cytotoxicity against HL-60 and K562 cells with IC₅₀ values of below 10 μg/mL better than those of the other isolated metabolites (IC₅₀ = 10.6–26.6 μg/mL). The results showed that the keto or hemiketal functionality might play an important role in cytotoxic activity of this class of compounds.