Racemic meroterpenoids from Ganoderma cochlear

Ganoderma cochlear, as edible and medicinal fungus, has long been used to prevent and treat various diseases. As our continuously phytochemical investigation of this fungus, a HPLC-UV-guided method led to the isolation of nine previously undescribed aromatic meroterpenoids with different ring systems, including six pairs of racemates, (±)-cochlearins A-E, G (1-5, 7), and three new analogues, cochlearins F, H and I (6, 8, 9). Their structures were elucidated by extensive 1D, 2D NMR spectroscopic data and MS analyses. The stereostructures of (±)-cochlearins A and B (1 and 2) were assigned using electronic circular dichroism (ECD) calculations. All of the isolates showed comparable antioxidant activities with IC₅₀ values of 3.1 ± 0.1-5.3 ± 0.1 μM, compared to the positive control (trolox, IC₅₀: 3.3 ± 0.1 μM). (±)-Cochlearin D (4) and (+)-4 exhibited weak inhibitory effects for the proliferation of hepatic stellate cells (HSCs) induced by transforming growth factor-β1 (TGF-β1).