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. Compound1 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.