Isolation and purification of seven lignans from Magnolia sprengeri by high-speed counter-current chromatography

Seven lignans including (−)-maglifloenone, futoenone, magnoline, cylohexadienone, fargesone C, fargesone A and fargesone B were isolated and purified from Magnolia sprengeri Pamp. using high-speed counter-current chromatography (HSCCC) with two-step separation. In the first step, a stepwise elution mode with the two-phase solvent system composed of petroleum ether–ethyl acetate–methanol–water (1:0.8:0.6:1.2, 1:0.8:0.8:1, v/v) was used and 15.6 mg of (−)-maglifloenone, 19.2 mg of futoenone, 10.8 mg of magnoline, 14.7 mg of cylohexadienone and 217 mg residues were obtained from 370 mg crude extract. In the second step, the residues were successfully separated by HSCCC with the solvent system composed of petroleum ether–ethyl acetate–methanol–water (1:0.8:1.2:0.6, v/v), yielding 33.2 mg of fargesone C, 47.5 mg of fargesone A and 17.7 mg of fargesone B. The purities of the separated compounds were all over 95% determined by HPLC. The chemical structures of these compounds were confirmed by 1H NMR, 13C NMR and ESI-MS.