COX-2 and iNOS inhibitory epimeric meroterpenoids from Ganoderma cochlear and structure revision of cochlearol Q

Abstract

Four novel epimeric meroterpenoids, ganadone A (1), 3′,10′-di-epi-ganadone A (2), 10′-epi-ganadone A (3), and 3′-epi-ganadone A (4) as well as another pairs of epimers, ganadone B (5) and 10′-epi-ganadone B (6), with a same basic skeleton compound ganadone C (7), together with two lactonized meroterpenoids, ganadones D and E (8 and 9) were isolated from the fruiting bodies of Ganoderma cochlear. Compounds 1–7 were constructed with fascinating adjacent 6′,7′-bifuran ring system. Fortunately, we have revised our previously reported structure cochlearol Q, which was proposed pyrano[6′,7′-b]pyran ring system into 6′,7′-bifuran motif. All the isolates were characterized by analysis of HRESIMS, NMR spectroscopy and 1 was supported by X-ray crystallography analysis. The absolute stereochemistry of 1–9 were assigned by quantum chemical calculations. Biological evaluation of 1–9 showed that 5, 6, and 9 have significant anti-inflammatory potentials.