Purification of Phenylalkanoids and Monoterpene Glycosides from Rhodiola rosea L. Roots by High-speed Counter-current Chromatography

Introduction - Rhodiola rosea L. is a medicinal herb used for its adaptogenic properties. The main active components are the phenylpropanoids collectively referred to as rosavins. Objectives - To develop an isolation method for phytochemicals present in Rhodiola rosea roots using high-speed countercurrent chromatography (HSCCC). Methodology - The roots of Rhodiola rosea were extracted with methanol and fractionated using liquid-liquid partition and polyamide column clean-up. The purified fraction (100 mg) was subjected to semi-preparative HSCCC using the two-phase solvent system ethyl acetate: butanol: water (3: 2: 5). The head-to-tail elution mode was employed with a flow rate of 1.5 mL/min and a rotary speed of 1000 rpm. Results - The separation yielded six main fractions with four components more than 90% pure. The sixth fraction was further purified using semi-preparative HPLC with a Synergi-hydro RP C-18-column to obtain rosin and geranyl 1-O-alpha-L-arabinopyranosyl (1 -> 6)-beta-D-glucopyranoside. The main components isolated were rosavin (3.4 mg, 97% purity), salidroside (0.5 mg, 90% purity), benzyl-O-beta-D-glucopyranoside (1.2 mg, 85% purity), rosarin (1.3 mg, 99% purity), rosiridin (1.8 mg, 92% purity), rosin (1.2 mg, 95% purity) and geranyl 1-O-alpha-L-arabinopyranosyl(1 -> 6)-beta-D-glucopyranoside (6.5 mg, 97% purity). The identity and purity of these components were confirmed using ultrafast liquid chromatography-diode-array detector-MS/MS analysis, 1 H-and C-13-NMR spectroscopy. Conclusion - High-speed counter-current chromatography was successful in the isolation of several phytochemicals present in Rhodiola rosea roots, including two components that are not commercially available. Copyright (C) 2012 John Wiley & Sons, Ltd.