Secovironolide, a novel furanosteroid scaffold with a five-membered B ring from the endophytic fungus Talaromyces wortmannii LGT-4

Secovironolide (1) was purified from the culture broth of Talaromyces wortmanni and is the first example of a furanosteroid scaffold bearing a five-membered B ring. The structure of 1 was elucidated by comprehensive NMR spectroscopy and single-crystal X-ray crystallography. Additional known viridian derivatives (2–5, 7) were isolated, including the new epoxide containing compound, epoxyvirone (6). Isolates were tested for monoamine oxidase (MAO) inhibitory activity and showed only weak activity.