Four New Dibenzo-α-pyrones From Helicosporium sexuale LZ15

Four new dibenzo-α-pyrone derivatives-helicolide A (1) and helicohydrins B-D (2-4)-along with five known analogues (5-9) were isolated from the fermented rolled-oat culture of Helicosporium sexuale LZ15. Their structures were determined by comprehensive spectroscopic analysis (1D/2D NMR, HRESIMS) and further confirmed by x-ray crystallography, NOE correlations, and ECD calculations. Structurally, helicolide A (1) is an isocoumarin derivative bearing carboxyl and acetyl groups, while Helicohydrins B-D (2-4) are polyhydroxylated fused isocoumarins. In vitro cytotoxicity assays revealed that compound 5 showed moderate cytotoxicity toward HeLa cells; compound 6 displayed moderate activity against HepG2 and HeLa; compound 7 exhibited weak cytotoxicity toward A2780 and A549; and compound 8 moderately inhibited A549 and weakly inhibited HeLa cells.