Heimionones A–E, New Sesquiterpenoids Produced by Heimiomyces sp., a Basidiomycete Collected in Africa

With heimionones A–E (1–5), five new terpenoids were isolated from submerged cultures of Heimiomyces sp. in addition to the previously described compounds hispidin, hypholomin B, and heimiomycins A and B. Planar structures of the metabolites were elucidated by 1D and 2D NMR in addition to HRESIMS data. While ROESY data assigned relative configurations, absolute configurations were determined by the synthesis of MTPA esters of 1, 3, and 5. The [6.3.0] undecane core structure of compounds 3–5 is of the asteriscane-type, however, the scaffold of 1 and 2 with their bicyclo [5.3.0] decane core and germinal methyl substitution is, to our knowledge, unprecedented. Together with several new compounds that were previously isolated from solid cultures of this strain, Heimiomyces sp. showed an exceptionally high chemical diversity of its secondary metabolite profile.