Unambiguous Determination of the Absolute Configuration of Dimeric Stilbene Glucosides from the Rhizomes of Gnetum africanum
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- 作者：Thierry Buffeteau ; Dominique Cavagnat ; Jonathan Bisson ; Axel Marchal ; Gilbert D. Kapche ; Ilaria Battistini ; Gregory Da Costa ; Alain Badoc ; Jean-Pierre Monti ; Jean-Michel M茅rillon ; Pierre Waffo-T茅guo
- 刊名：Journal of Natural Products
- 出版年：2014
- 出版时间：August 22, 2014
- 年：2014
- 卷：77
- 期：8
- 页码：1981-1985
- 全文大小：294K
- ISSN：1520-6025
文摘
Dimeric stilbene glucosides 1鈥?b>3 [two diastereomers of (鈭?-gnemonoside A (1a and 1b), (鈭?-gnemonoside C (2), and (鈭?-gnemonoside D (3)] as well as a mixture of the two enantiomers of gnetin C (4) were isolated from the rhizomes of Gnetum africanum. The two enantiomers of gnetin C, (+)-4 and (鈭?-4, were obtained from the aglycones of 1a and 1b, respectively. The configurations of these stilbenoids were investigated by NMR and vibrational circular dichroism (VCD) experiments. The absolute configurations of (鈭?-1a, (鈭?-2, (鈭?-3, and (鈭?-4 were established as 7aS,8aS by VCD spectroscopy in combination with density functional theory calculations. The antiamyloidogenic activity of the isolated stilbenes was also evaluated versus beta-amyloid fibrils. The four glucosides of gnetin C (1a, 1b, 2, and 3) were found to be the most active compounds, with inhibition percentages of 56, 56, 58, and 54 at 10 渭M, respectively.