Tetrahedron, 22 July 2012, Vol.68(29), pp.5817-5823
The concomitant addition of a histone deacetylase inhibitor, suberoyl bis-hydroxamic acid, and a DNA methyltransferase inhibitor, RG-108, to the culture medium of , an entomopathogenic fungus, induced a significant increase in diversity of secondary metabolites. From the culture media were isolated two new highly oxidized ergosterols, formosterols A ( ) and B ( ), and five new isariotin analogs, 12′- -acetylisariotin A ( ), 1- -isariotin A ( ), and isariotins K–M ( – ), together with 22,23-epoxy-3,12,14,16-tetrahydroxyergosta-5,7-dien-11-one (named formosterol C) ( ), isariotins A ( ), C ( ), and E ( ), TK-57-164A ( ), and beauvericin ( ). The NMR spectra, X-ray single crystallographic diffraction, and chemical transformations revealed the structures of the two new formosterols and five new isariotins. The stereochemistry of formosterol C ( ) was deduced from its spectroscopic data. The side chains of formosterols A–C ( – ) contained -22,23-epoxide, which is rarely present in naturally occurring sterols and triterpenes.
View record in ScienceDirect (Access to full text may be restricted)