Chaeglobol A, an unusual octocyclic sterol with antifungal activity from the marine-derived fungus Chaetomium globosum HBU-45

Chemical investigation of the marine-derived fungus Chaetomium globosum HBU-45 led to the discovery of chaeglobol A (1). Its structure was determined by spectroscopic analysis, computational electronic circular dichroism (ECD)/optical rotatory dispersion (ORD) methods, and X-ray crystallography. Compound 1 represents a new skeleton with an uncommon 6/6/6/5/6/5/6/5 octacyclic system, which is presumably biosynthesized via a [4+2] cycloaddition and an enzymatic cyclization. Chaeglobol A (1) exhibited inhibitory activity against B. dothidea by destroying cell membrane integrity and causing oxidative damage within the cells.