Isolation and purification of phenylethanoid glycosides from Cistanche deserticola by high-speed counter-current chromatography
Five phenylethanoid glycosides (PhGs), echinacoside, cistanoside A, acteoside, isoacteoside and 2′-acetylacteoside, were isolated and purified from Cistanche deserticola for the first time by high-speed counter-current chromatography (HSCCC) using two biphasic systems, one consisting of ethyl acetate–ethanol–water (5:0.5:4.5, v/v/v) and another of ethyl acetate–n-butanol–ethanol–water (0.5:0.5:0.1:1, v/v/v/v). A total of 28.5 mg of echinacoside, 18.4 mg of cistanoside A, 14.6 mg of acteoside, 30.1 mg of isoacteoside and 25.2 mg of 2′-acetylacteoside were purified from 1412 mg of the n-butanol extract of C. deserticola, each at over 92.5% purity as determined by HPLC. The structures were identified by their retention time, UV, LC–ESI-MS in the negative ion mode, and confirmed by NMR experiments. The characteristic LC–ESI-MSn fragmentation pattern of the five compounds is discussed, and found to be a very specific and useful tool for the structural identification of PhGs from this important medicinal plant.