Research

April 23, 2013

Preparative Isolation and Purification of Three Stilbene Glycosides from the Tibetan Medicinal Plant Rheum tanguticum Maxim. Ex Balf. by High-speed Counter-current Chromatography

Introduction – Stilbene glycosides are the primary constituents of Rheum tanguticum Maxim. ex Balf., to which different bioactivities has been attributed, including: anti-HIV, anti-oxidant, anti-tumour, anti-malarial, and anti-allergy activity.
However, effective methods for the isolation and purification of stilbene glycosides, such as trans-rhapontin, cis-rhapontin and trans-desoxyrhaponticin, from this herb are not currently available.
Objective – To develop an efficient method for the preparative isolation and purification of three stilbene glycosides from Rheum tanguticum Maxim. ex Balf. via high-speed counter-current chromatography (HSCCC).
Methods – A solvent system composed of chloroform:n-butanol:methanol:water (4:1:3:2, v/v/v/v) was developed for the separation. The upper phase was used as the stationary phase, and the lower phase was used as the mobile phase. The flow rate was 1.8 mL/min. The apparatus was controlled at 800 rpm and 25 oC, and the effluent was monitored at 280 nm. Chemical constituents were analysed by high-performance liquid chromatography (HPLC), and their structures were identified by 1 H- and 13C-NMR.
Results – Under the optimised conditions, 25.5mg trans-rhapontin, 16.0mg cis-rhapontin and 20.5mg trans-desoxyrhaponticin were separated from 80mg crude sample; the isolates had purities of 99.6, 97.2 and 99.2%, respectively.
Conclusion – A simple and efficient HSCCC method has been optimised for the preparative separation of stilbene glycosides from Rheum tanguticum Maxim. ex Balf.

Figure 1. The chemical structures of trans-rhapontin (1), cis-rhapontin (2) and trans-desoxyrhaponticin (3).
 
Additional Information:
1. Author Information:Xiaohui Zhao,Fa Han,Yulin Li,Huilan Yue
Correspondence:  xhzhao@nwipb.ac.cn
2. Publication History: Phytochem. Anal. 2013, 24, 171–175

Preparative Isolation and Purification....pdf