Department of Chemistry, Uppsala BioCenter, Swedish University of Agricultural Sciences, P.O. Box 7015, Uppsala SE-75007, Sweden.
Molecules. 2012 Jun 25;17(7):7769-81. doi: 10.3390/molecules17077769.
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.
从导致枯梢病的真菌 Hymenoscyphus pseudoalbidus 的液体培养物中分离得到两种与 viridin 相关的 B-降孕甾烷，B-降孕甾烷内酯（1）和 B-降孕甾烷烯醇（2），它们都具有独特的前所未有的碳骨架。发现化合物 2 降解为第三种 B-降孕甾烷化合物，1β-羟基-2α-氢-asterogynin A（3），后来在原始培养物中检测到。1 的结构在连接性方面与 TAEMC161 的原始错误结构相同，后者后来被重新分配为 viridiol。化合物 2 通过分子内氢键显示出前所未有的 ¹H-¹³C HMBC 相关。提出化合物 1-3 的五员 B 环是通过苯并酸重排形成的。已知化合物 asterogynin A 被发现是由 3 通过β-消除水形成的。所有化合物均通过 NMR 光谱、LC-HRMS 和旋光性进行了表征。
