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B-norsteroids from Hymenoscyphus pseudoalbidus
Department of Chemistry, Uppsala BioCenter, Swedish University of Agricultural Sciences, P.O. Box 7015, Uppsala SE-750 07, Sweden
Department of Forest Mycology and Plant Pathology, Uppsala BioCenter, Swedish University of Agricultural Sciences, P.O. Box 7026, Uppsala SE-750 07, Sweden
* Author to whom correspondence should be addressed.
Received: 5 June 2012; in revised form: 13 June 2012 / Accepted: 15 June 2012 / Published: 25 June 2012
Abstract: 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, 1β-hydroxy-2α-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 1–3 was proposed to be formed by a benzilic acid rearrangement. The known compound asterogynin A was found to be formed from 3 by a β-elimination of water. All compounds were characterized by NMR spectroscopy, LC-HRMS and polarimetry.
Keywords: Hymenoscyphus pseudoalbidus; Chalara fraxinea; B-norsteroids; secondary metabolites; structure elucidation
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MDPI and ACS Style
Andersson, P.F.; Bengtsson, S.; Stenlid, J.; Broberg, A. B-norsteroids from Hymenoscyphus pseudoalbidus. Molecules 2012, 17, 7769-7781.
Andersson PF, Bengtsson S, Stenlid J, Broberg A. B-norsteroids from Hymenoscyphus pseudoalbidus. Molecules. 2012; 17(7):7769-7781.
Andersson, Pierre F.; Bengtsson, Stina; Stenlid, Jan; Broberg, Anders. 2012. "B-norsteroids from Hymenoscyphus pseudoalbidus." Molecules 17, no. 7: 7769-7781.