Screening and isolating potential α-glucosidase inhibitors from Rhizoma Coptidis by ultrafiltration LC-PDA-ESI/MS combined with high-speed countercurrent chromatography and reverse-phase medium-pressure liquid chromatography

Abstract

Rhizoma Coptidis is an alkaloid-rich herbal drug used in Chinese herbal medicine. Currently, conventional methods for screening and isolating alkaloids are labor-intensive and time-consuming. In the present study, ultrafiltration liquid chromatography with photodiode array detection coupled to electrospray ionization tandem mass spectrometry (ultrafiltration liquid chromatography-photodiode array detector-electrospary ionization mass spectrometry (LC-PDA-ESI/MS)) were applied to screen and identify α-glucosidase inhibitors in R. Coptidis. High-speed countercurrent chromatography and reverse-phase medium-pressure liquid chromatography were applied to separate and isolate the active constituents. As a result, five major compounds in R. Coptidis were screened and identified as α-glucosidase inhibitors by ultrafiltration LC-PDA-ESI/MS. Five ligands, jatrorrhizine, epiberberine, coptisine, palmatine, and berberine, were isolated by reverse-phase medium-pressure liquid chromatography and high-speed countercurrent chromatography. The purities of the five compounds as determined by high-performance liquid chromatography were 76.20, 75.13, 82.24, 93.78, and 92.01%, respectively. The results indicate that systematic isolation of bioactive components in R. Coptidis guided by ultrafiltration LC-PDA-ESI/MS is a feasible and efficient technique that could be extended to separation of other enzyme inhibitors.