Anthrasteroids were first encountered as acid rearrangement products of the fungal steroid ergosterol and then as geomarkers in deep-sea shale deposits, and while 3α-hydroxyanthrasteroids have been reported as fungal metabolites, 2β-hydroxyanthrasteroids remain rare. Our investigation of Australian soil-derived fungi yielded the 2β-hydroxyanthrasteroid pullenvasterols A-G (1-7), with structures assigned by spectroscopic and chemical analysis and biosynthetic considerations. Of note, 4 and 5 selectively inhibit the growth of coisolated fungi, suggestive of an ecological antifungal defense.
Wang et al. (Wed,) studied this question.