Lipidated steroid saponins from Dioscorea villosa (wild yam)

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• 作者：Shi-Hui Dong ; Geping Cai ; Jos茅 G. Napolitano ; Dejan Nikoli膰 ; David C. Lankin ; James B. McAlpine ; Richard B. van Breemen ; Djaja D. Soejarto ; Guido F. Pauli ; Shao-Nong Chen
• 关键词：Dioscorea villosa ; Wild yam ; Metabolomic mining ; Lipidated steroid saponins ; Residual complexity
• 刊名：Fitoterapia
• 出版年：December, 2013
• 年：2013
• 卷：91
• 期：Complete
• 页码：113-124
• 全文大小：1052 K

文摘

Two groups of lipidated steroid saponins including seven new compounds (2, 3, 5, and 7-10) were isolated from the widely used botanical, wild yam (Dioscorea villosa), employing a fractionation protocol of metabolomic mining. This methodology recently led to the isolation of 14 diarylheptanoids from the same plant. Together with these lipidated steroid saponins, they establish additional new markers for D. villosa. The lipidation of steroids with analog long-chain fatty acids containing different degrees of unsaturation generates an entire series of compounds which are difficult to purify and analyze. The structures of the two series of lipidated steroid saponins (series A and B) were established by a combination of 1D and 2D NMR as well as GC-MS after chemical modification. Series A was determined to be a mixture of lipidated spirostanol glycosides (1-5), while series B (6-10) was proved to be a mixture of five lipidated clionasterol glucosides. The latter group represents the first derivatives of clionasterol to be found in D. villosa. The discovery of this specific structural type of aliphatic esters of steroid saponins expands the characterization of the secondary metabolome of D. villosa. It may also inspire biological studies which take into account the lipophilic character and significantly altered physiochemical characteristics of these otherwise relatively polar phytoconstituents.