One-step Separation of Three Flavonoids from Poacynum hendersonii by High-speed Counter-current Chromatography

Introduction - Owing to them having the same traditional name, the leaves of Apoacynum venetum and Poacynum hendersonii are used indiscriminately in some areas of China. Although a series of studies have been conducted on Apoacynum venetum, there are only a few studies on Poacynum hendersonii. Objective - To develop an efficient method for the preparative isolation and purification of flavonoids from the leaves of Poacynum hendersonii by high-speed counter-current chromatography (HSCCC). Methodology - Powdered Poacynum hendersonii lead was extracted three times with 75% ethanol at 60 degrees C for 3 h. The distribution constant (K-D) was measured to select an optimal two-phase solvent system for HSCCC separation. The purities of the target compounds were tested using HPLC and their structures were identified by H-1-NMR and C-13-NMR. Results - Using a two-phase solvent system composed of n-butanol-petroleum ether-0.5% acetic acid (5:3:5, v/v), three main flavonoids, i.e. isoquercitrin, quercetin-3-O-sophoroside and quercetin-3-O-(6 ''-O-malonyl)-beta-D-glucoside, were separated from 240 mg crude sample in a one-step separation by using HSCCC method. After further purification with a Sepdex-LH20 column, 5.7 mg isoquercitrin (LC purity 98.72%), 4.9 mg quercetin-3-O-sophoroside (LC purity 99.06%) and 7.4 mg quercetin-3-O-(6 ''-O-malonyl)-beta-D-glucoside (LC purity 99.31%) were obtained, respectively. Conclusion - The optimised high-speed counter-current chromatography method is fast, simple and efficient for the preparative separation of flavonoids from the leave of Poacynum hendersonii. Copyright (C) 2011 John Wiley & Sons, Ltd.