Ultrafiltration LC-PDA-ESI/MS combined with reverse phase-medium pressure liquid chromatography for screening and isolation potential α-glucosidase inhibitors from Scutellaria baicalensis Georgi

Diabetes mellitus (DM) has become a worldwide health problem. α-Glucosidase inhibitors are widely used in the treatment of type 2 diabetes, and natural products are considered as the promising sources of α-glucosidase inhibitors. In this research, ultrafiltration liquid chromatography with photodiode array detection coupled to electrospray ionization tandem mass spectrometry (Ultrafiltration LC-PDA-ESI/MS) were applied to screen and identify α-glucosidase inhibitors from Scutellaria baicalensis. Following this, reverse-phase medium-pressure liquid chromatography (RP-MPLC) was applied to separate and isolate the active constituents. As a result, eleven major compounds in S. baicalensis were screened and identified as α-glucosidase inhibitors by Ultrafiltration LC-PDA-ESI/MS and six ligands, baicalin, wogonoside, 5,7,3,2′,6′-pentahydroxy flavanone, chrysin-6-C-arabinosyl-8-C-glucoside, chrysin-6-C-glucosyl-8-C-arabinoside and wogonin, were isolated by RP-MPLC. The purities of the six compounds were 89.7%, 83.5%, 76.2%, 93.7%, 75.1% and 96.2%, respectively, as determined by high performance liquid chromatography. The results demonstrate that the method for systematic isolation of bioactive components in S. baicalensis guided by Ultrafiltration LC-PDA-ESI/MS is a feasible and efficient technique and could be expected to extend for the separation of other enzyme inhibitors.