Silvaglins and related 2,3-secodammarane derivatives – unusual types of triterpenes from Aglaia silvestris
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- 作者：Silvia Pointinger ; Somnuk Promdang ; Srunya Vajrodaya ; Caroline M. Pannell ; Otmar Hofer ; Kurt Mereiter ; Harald Greger
- 关键词：Aglaia silvestris ; Meliaceae ; Secodammarane triterpenes ; Pregnane steroid ; Shoreic acid ; Isoeichlerianic acid ; Silvaglines ; Aglasilvinic acid ; Pregnacetal ; Chemotaxonomy
- 刊名：Phytochemistry
- 出版年：2008
- 出版时间：November 2008
- 年：2008
- 卷：69
- 期：15
- 页码：2696-2703
- 全文大小：308 K
文摘
Lipophilic crude extracts of leaves, stem and root bark of six different provenances of Aglaia silvestris were compared to determine species-specific chemical trends as well as infraspecific variability. 3,4-Secodammarane triterpenes formed the basic chemical equipment accompanied by the 2,3-seco derivative aglasilvinic acid, probably representing the precursor of the silvaglin A and isosilvaglin A characterised by a five membered ring A. In addition, the pregnane steroid pregnacetal was isolated and identified together with the known sesquiterpenes α-muurolene and viridiflorol, and the bisamide pyramidatin. Depending on the collection site all major triterpenes showed two different stereochemical trends either towards 20R or 20S configuration, giving rise to isolation and identification of the two isomers methylisofoveolate B (20S,24R) and methylfoveolate B (20R,24S) as well as the known derivatives shoreic acid (20S,24R), isoeichlerianic acid (20R,24S), and methylisoeichleriate (20R,24S). The structures were elucidated by 2D-NMR experiments and silvaglin A additionally by X-ray diffraction. The structural diversity and distribution of triterpenoids within the genus Aglaia is highlighted with respect to chemotaxonomic implications.