Preparative isolation of six platycosides from Platycodi Radix by high-speed counter-current chromatography with evaporative light scattering detection

Abstract

Platycodi Radix, the root of Platycodon grandiflorum A. DC. (Campanulaceae), has traditionally been used as medicinal herb. Its primary constituents, platycosides (saponins), are known to have diverse functionalities, exerting anti-inflammation, anti-allergy, anti-tumor, anti-obesity and anti-hyperlipidemia effects, as well as augmenting immune responses and stimulating apoptosis in skin cells. To this date, some studies isolating the various platycosides according to their specific biological activities have been published. The present work explains how high-speed counter-current chromatography (HSCCC) coupled with ELSD was applied to the preparative separation of six platycosides (platycoside E, platycodin D, platycodin D3, and their deapiose forms) from Platycodi Radix. The HSCCC, with a two-phase solvent system composed of hexane-n-butanol-water (1:40:20, v/v) and hexane-n-butanol-water (1:10:5, v/v), in combination with effluent monitoring by ELSD, was successfully performed. Consequently, platycoside E (21mg), deapio-platycoside E (14mg), platycodin D3 (10mg), deapio-platycodin D3 (6mg), platycodin D (28mg), and deapio-platycodin D (6mg), all with purities of over 94%, were isolated from 300mg of the platycoside-enriched fraction. Additionally, their structures were characterized by electrospray ionization mass spectrometry (ESI-MS), 1H NMR, and 13C NMR.