%0 Journal Article
%T B-norsteroids from Hymenoscyphus pseudoalbidus
%A Pierre F. Andersson
%A Stina Bengtsson
%A Jan Stenlid
%A Anders Broberg
%J Molecules
%D 2012
%I MDPI AG
%R 10.3390/molecules17077769
%X Two viridin-related B-norsteroids, B-norviridiol lactone (1) and B-norviridin enol (2), both possessing distinct unprecedented carbon skeletons, were isolated from a liquid culture of the ash dieback-causing fungus Hymenoscyphus pseudoalbidus. Compound 2 was found to degrade to a third B-norsteroidal compound, 1¦Â-hydroxy-2¦Á-hydro-asterogynin A (3), which was later detected in the original culture. The proposed structure of 1 is, regarding connectivity, identical to the original erroneous structure for TAEMC161, which was later reassigned as viridiol. Compound 2 showed an unprecedented 1H-13C HMBC correlation through an intramolecular hydrogen bond. The five-membered B-ring of compounds 1¨C3 was proposed to be formed by a benzilic acid rearrangement. The known compound asterogynin A was found to be formed from 3 by a ¦Â-elimination of water. All compounds were characterized by NMR spectroscopy, LC-HRMS and polarimetry.
%K Hymenoscyphus pseudoalbidus
%K Chalara fraxinea
%K B-norsteroids
%K secondary metabolites
%K structure elucidation
%U http://www.mdpi.com/1420-3049/17/7/7769