ISOLATION AND PURIFICATION OF SAPONINS FROM PLATYCODON GRANDIFLORUM BY SEMI-PREPARATIVE HIGH PERFORMANCE LIQUID CHROMATOGRAPHY AND LC/ESI-MS

In this work, the isolation and purification of saponins (platycosides) from the roots of Platycodon grandiflorum, including deapio-platycodin D, platycodin D, and polygalacin D, was investigated using semi-preparative high performance liquid chromatography (SP-HPLC). The chromatographic separation was carried out on a Zorbax Eclipse XDB C18 column (250 mm × 9 mm; 10 µm). The conversion of separation condition from analytical level to preparative level was successfully achieved by optimizing mobile phase, flow rate, and sample load. A satisfactory separation of platycosides was obtained with 3.5 mL/min of flow rate in less than 40 min. Chromatography was performed using binary mobile phase composed of methanol-water with gradient elution and a sample load of 100 mg. UV detection was set at 210 nm. With the optimal chromatographic conditions, the purity of each platycoside was more than 98.5%. Furthermore, the molecular weights of platycosides were identified by HPLC-ESI-MS analysis in both positive and negative modes, and then their structures were further elucidated by IR, UV, and 13C-NMR spectroscopy data. The present method is robust and suitable for preparing available quantities of pure platycosides from P. grandiflorum in conventional laboratories.