Purification of Four Flavonoid Glycosides from Lotus (Nelumbo nucifera Gaertn) plumule by Macroporous Resin Combined with HSCCC

High-speed counter-current chromatography (HSCCC) combined with macroporous resin (MR) column was successfully applied to the isolation and purification of four flavonoid glycosides from the medicinal herb Lotus plumule (LP). A polar two-phase solvent system composed of ethyl acetate-n-butanol-water (1:2:3, v/v/v) was selected by high-performance liquid chromatography (HPLC) and run on a preparative scale where the lower aqueous phase was used as the mobile phase with a head-to-tail elution mode. Quercetin-3-O-β-D-glucopyranoside (15 mg), isorhamnetin-3-O-β-D-glucopyranoside (13 mg), apigenin 6-C-β-D-glucopyranosyl-8-C-α-L-arabinopyranoside (18 mg) and apigenin 6,8-di-C-β-D-glucopyranoside (48 mg) were obtained in a one-step HSCCC separation from 240 mg of the sample. The purity of each compound was over 95% as determined by HPLC. Chemical structures of the isolated compounds were identified by electrospray ionization mass spectrometry (ESI-MS-MS) and nuclear magnetic resonance (NMR) methods. Moreover, the four compounds were isolated from LP for the first time.