Abstract
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.
ACKNOWLEDGMENT
This work was supported by the grant from Jilin Science & Technology Development Plan (20100938).