Preparative Isolation and Purification of Cucurbitacins from Pedicellus Melo by High-Speed Counter-corrent Chromatography

A preparative high-speed counter-current chromatography (HSCCC) was used to isolate and separate cucurbitacins from Pedicellus Melo. A successful isolation and purification was achieved at the following conditions; the two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water at a volume ratio of 1. 2:0. 8:0. 8:1. 2 was selected and the lower phase of the system was used as the mobile phase at the flow rate of 2. 0 mL/min, the isolation temperature and revolution speed were set at 25 degrees C and 800 r/min, respectively. In 4. 0 h, the isolation produced a total of 33. 5 mg cucurbitacin B, 21.7 mg cucurbitacin E, and 14.9 mg cucurbitacin I with purities of 99. 1%, 98. 3% and 97. 5%, respectively, determined by high performance liquid chromatography from 200 mg crude extract after cleaning-up by XAD-16 macroporous resin, which was necessary for the excellent purification. The chemical structure identification was carried out by H-1-NMR and C-13-NMR.