One-step preparative separation of two polyhydroxystilbenes from Rheum likiangense Sam. by high-speed counter-current chromatography.

INTRODUCTION The official rhubarb species have frequently been investigated for their hydroxyanthraquinone components and associated pharmacological properties. However, other unofficial rhubarb species were rarely studied until polyhydroxystilbenes (PHS), which commonly occur in the unofficial rhubarb, revealed a range of potential bioactivities. Hence, there has been increasing interest in the efficient preparation of high-purity PHS for pharmacological and clinical trials. OBJECTIVE To develop a suitable method for large-scale preparative separation of PHS from the rhizome of Rheum likiangense Sam. by high-speed counter-current chromatography (HSCCC). RESULTS Two PHS compounds were isolated successfully within 440 min using a solvent system consisting of methanol:n-butanol:chloroform:water (2:0.5:3:3, v/v/v/v). Eighty-four milligrams of desoxyrhaponticin with 98.2% purity and 148 mg of rhaponticin with 95.3% purity were respectively yielded from 1.5 g of crude extract in the single, one-step operation. CONCLUSION An optimised HSCCC method has been established for large-scale preparative separation of PHS compounds from Rheum likiangense Sam.