Vibralactone Biogenesis-Associated Analogues from Submerged Cultures of the Fungus Boreostereum vibrans.

A scale-up fermentation of the fungus Boreostereum vibrans facilitated the isolation of six new vibralactone biogenesis-associated analogues, namely vibralactamide A (1), vibralactone T (2), 13-O-lactyl vibralactone (3), 10-O-acetyl vibralactone G (4), (11R,12R)- and (11S,12R)-vibradiol (5, 6). Their structures were established via extensive spectroscopic analyses, specific optical rotation comparison, and Snatzke's method. The biosynthetic pathway for vibralactamide A was postulated. The absolute configuration of vibralactone B was revised by single crystal X-ray diffraction analysis. This work puts the divergent vibralactone biosynthesis pathway one step further and expands the structural diversity of vibralactone-associated compounds.