Separation and purification of alpha-glucosidase inhibitors from Polygonatum odoratum by stepwise high-speed counter-current chromatography combined with Sephadex LH-20 chromatography target-guided by ultrafiltration-HPLC screening

摘要

Although Polygonatum odoratum has been widely used as medicinal plant and food supplement for treating diabetes, little is known regarding its bioactive components. In this study, ultrafiltration-HPLC based ligand screening was developed to screen alpha-glucosidase inhibitors from P. odoratum for the first time. Then bioactive components were target-guided separated by combining stepwise high-speed countercurrent chromatography (HSCCC) using petroleum ether ethyl acetate methanol water (1:4:0.8:4.2, v/v/v/v), (1:4:1.8:3.2, v/v/v/v) and (1:4:2.3:2.7, v/v/v/v) as solvent systems with Sephadex LH-20 chromatography eluted by MeCN-MeOH (1:1, v/v). Five phenethyl cinnamides, N-cis-feruloyloctopamine (1); N-trans-p-coumaroyloctopamine (2), N-trans-feruloyloctopamine (3), N-trans-p-coumaroyltyramine (4) and N-trans-feruloyltyramine (5), and four homoisoflavanones, (3R)-5,7-dihydroxyl-3-(2',4'-dihydroxylbenzyl)-chroman-4-one (6), (3R)-5,7-dihydroxyl-6-methyl-3-(4'-hydroxylbenzyl)-chroman-4-one (7), (3R)-5,7-dihydroxyl-6-methyl-8-methoxyl-3-(4'-hydroxylbenzyl)-chroman-4-one (8); and (3R)-5,7-dihydroxyl-6,8-dimethyl-3-(4'-hydroxylbenzyl)-chroman-4-one) (9), with purity over 98.5% were purified, and their structures were identified by UV, MS, and H-1 NMR. Notably, compounds 2 and 4 were first reported in genus Polygonatum, while compound 1 was first obtained from family Liliaceae. In addition, alpha-glucosidase inhibitory activities of compounds 1-9 were evaluated, and compounds 2 and 4 exhibited stronger alpha-glucosidase inhibitory activity with IC50 values of 2.3 and 2.7 mu M. The results suggested the potential medicinal use of P. odoratum, and the technology could be widely applied for rapid screening and preparative separation of a group of bioactive compounds from complex matrix. (C) 2015 Elsevier B.V. All rights reserved.