Separation of α‐amylase inhibitors from <i>Abelmoschus esculentus</i> (L).Moench by on‐line two‐dimensional high‐speed counter‐current chromatography target‐guided by ultrafiltration‐HPLC

Abstract

In this study, an on‐line two‐dimensional high‐speed counter‐current chromatography system based on a six‐port valve was developed. Target‐guided by ultrafiltration with high‐performance liquid chromatography, the one‐step isolation of three potential α‐amylase inhibitors from Abelmoschus esculentus (L).Moench was achieved by employing the developed orthogonal system and extrusion elution mode. The purities of three potential α‐amylase inhibitors were all over 95% as determined by high‐performance liquid chromatography. Furthermore, UV, mass spectrometry and 1 H NMR spectroscopy were applied to the structural identification of the isolated three target compounds, their structures were assigned as quercetin‐3‐ O ‐sophoroside (i), 5,7,3′,4′‐tetrahydroxy flavonol‐3‐ O ‐[β‐ d ‐rhamnopyranosil‐(1→2)]‐β‐ d ‐glucopyranoside (ii ) and isoquercitrin (iii), respectively. The Results demonstrated that the proposed method was highly efficient to screen and isolate enzyme inhibitors from complex natural products extracts, and on‐line two‐dimensional high‐speed counter‐current chromatography can effectively increase the peak resolution of target compounds.