Cyathane diterpenoids and drimane sesquiterpenoids with neurotrophic activity from cultures of the fungus Cyathus africanus.

Five terpenoids, including two new cyathane diterpenoids neocyathin S (1) and neocyathin T (2), together with three drimane sesquiterpenoids, one known 3β,6β-dihydroxycinnamolide (3), two new ones 3β,6α-dihydroxycinnamolide (4) and 2-keto-3β,6β-dihydroxycinnamolide (5), were isolated from the cultures of the basidiomycete Cyathus africanus. Their structures were established based on extensive spectroscopic methods including 2D NMR (HSQC, 1H‒1H-COSY, HMBC, ROESY) and HRESIMS experiments. The absolute configurations of two pairs of epimers, 1 and 2 as well as 3 and 4, were determined by ECD quantum chemical calculation. All the five compounds enhanced nerve growth factor (NGF)-mediated neurite outgrowth using rat pheochromocytoma (PC12) cells at concentration 10 µM.