New Anthocyanidin and Anthocyanin Pigments from Blue Plumbago
详细信息 查看全文
- 作者：Irene Skaar ; Monica Jordheim ; Robert Byamukama ; Angella Mbabazi ; Sileshi G. Wubshet ; Bernard Kiremire ; 脴yvind M. Andersen
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2012
- 出版时间：February 15, 2012
- 年：2012
- 卷：60
- 期：6
- 页码：1510-1515
- 全文大小：210K
- 年卷期：v.60,no.6(February 15, 2012)
- ISSN：1520-5118
文摘
Phytochemical investigations of blue plumbago (Plumbago auriculata Poir. syn. Plumbago capensis Thunb.) flowers have led to the isolation of six new anthocyanins based on three new anthocyanidins with 5,7-dimethoxylated A-rings. Their structures were identified by 2D nuclear magnetic resonance and high-resolution mass spectrometry as the 3-O-尾-galactopyranosides (1,2,4) and 3-O-伪-rhamnopyranosides (3,5,6) of 5,7-dimethyldelphinidin, 5,7-dimethylpetunidin, and 5,7-dimethylmalvidin. Identification of 1鈥?b>6 implies new structures for the previously reported anthocyanidins pulchellidin, europinidin, and capensinidin to be 5,7-dimethoxy-3,3鈥?4鈥?5鈥?tetrahydroxyflavylium, 5,7,3鈥?trimethoxy-3,4鈥?5鈥?trihydroxyflavylium, and 5,7,3鈥?5鈥?tetramethoxy-3,4鈥?dihydroxyflavylium cations, respectively. The anthocyanins (0.4 mg/g flowers) were accompanied by the dihydroflavonol taxifolin 3鈥?O-尾-glucopyranoside (1.4 mg/g) and the flavonols 5-methylquercetin 3-O-伪-rhamnopyranoside (8.8 mg/g) and 5-methylquercetin (0.4 mg/g). The anthocyanins 1鈥?b>6 are the first reported natural anthocyanins with no free hydroxyl groups in their 5- and 7-positions on their A-rings. They have thus no possibility of forming the tautomeric quinonoidal bases (anhydrobases), which are related to the free hydroxyl groups in the 5- and 7-positions of previously reported anthocyanins. The genes behind the 5,7-dimethoxylated anthocyanins might be useful for making anthocyanins with special properties (colors, etc.).