Arundinols A–C and Arundinones A and B from the Plant Endophytic Fungus Microsphaeropsis arundinis

Three new ent-eudesmane sesquiterpenoids, arundinols A–C (1–3), one isochroman-1-one, arundinone A (4), and a polyoxygenated benzofuran-3­(2H)-one dimer, arundinone B (5), were isolated from the extract of a plant endophytic fungus, Microsphaeropsis arundinis. Their structures were elucidated primarily by NMR experiments, and 1 was confirmed by X-ray crystallography. The absolute configuration of 1 was assigned by X-ray crystallography using Cu Kα radiation, whereas those of the C-11 tertiary alcohols in 2 and 3 were deduced via the circular dichroism data of the in situ formed [Rh2(OCOCF3)4] complexes. Arundinone B (5) represents the first dimeric benzofuran-3­(2H)-one, showing cytotoxicity against T24 and A549 cells. The co-isolated known compound 6 showed a modest inhibitory effect against Staphylococcus aureus.