Genepolide, a Sesterpene γ-Lactone with a Novel Carbon Skeleton from Mountain Wormwood (Artemisia umbelliformis)
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- 作者：Giovanni Appendino ; Orazio Taglialatela-Scafati ; Adriana Romano ; Federica Pollastro ; Cristina Avonto ; Patrizia Rubiolo
- 刊名：Journal of Natural Products
- 出版年：2009
- 出版时间：March 27, 2009
- 年：2009
- 卷：72
- 期：3
- 页码：340-344
- 全文大小：123K
- 年卷期：v.72,no.3(March 27, 2009)
- ISSN：1520-6025
文摘
The sesterpene γ-lactone genepolide (5) has been isolated from a Swiss horticultural variety of mountain wormwood (Artemisia umbelliformis) developed as a thujones-free alternative to native Western Alps wormwoods for the production of liqueurs. Genepolide is the formal Diels−Alder adduct of the exomethylene-γ-lactone costunolide (2) and the diene myrcene (6), two poorly reactive partners in cycloaddition reactions, and its structure was elucidated through a combination of spectroscopic methods. An investigation on the thermal stability of mixtures of 2 and 6, as well as considerations on the sensitivity of 2 to Brønsted and Lewis acids, suggests that 5 is a genuine natural product and that the Swiss chemotype of A. umbelliformis contains Diels−Alderase enzymatic activity that is lacking in native mountain wormwoods from Western Alps. Remarkable differences in thermal and acid-catalyzed reactions of the cyclodecadiene moiety of 2 and 5 suggest that quaternarization at C-11 has far-reaching effects on the reactivity of their homoconjugated medium-sized diene system. The wide occurrence of this structural motif in sesquiterpenoids makes this issue worth a systematic investigation.