Separation and purification of echinacoside from Penstemon barbatus (Can.) Roth by recycling high-speed counter-current chromatography.

Echinacoside is an important bioactive compound extracted from Cistanche tubulosa which was endangered by overexploitation. It is imperative to find an alternative source. Echinacoside was isolated from Penstemon barbatus (Can.) Roth for the first time. The peak contents of echinacoside are 9.09±0.32mg/g and 7.25±0.36mg/g respectively in the leaves and roots annually. The methanolic extracts from 20g of dried powder of the roots of P. barbatus were pre-purified by AB-8 resin and the fraction containing echinacoside was further purified by conventional high-speed counter-current chromatography (HSCCC) and recycling HSCCC with the solvent system n-butanol-water (1:1, v/v). Totally 42.0mg echinacoside with a purity of 96.3% was recovered. The recovery rate of echinacoside by recycling HSCCC reached 91.0%. The structure of our echinacoside confirmed by IR, (1)H NMR and (13)C NMR is identical to the standard sample. This indicates that P. barbatus might be ideal source for preparation of large scale of echinacoside.