Abstract:

Screening and analysis of bioactive compounds from natural products is a challen-ging work due to their complexity. This paper reports the hyphenation of affinity solid-phase extraction column (ASEC) using immobilized α-glucosidase and high performance liquid chromatography-diode array detector-quadrupole time-of-flight mass spectrometry (HPLC-DAD-Q-TOF-MS) for screening and identification of α-glucosidase binding compounds from Chinese medicines. Affinity solid-phase extraction (ASE) system was hyphenated with HPLC system via a four-port switching valve and a six-port injection valve as an interface for transferring effluents from ASE column to HPLC. Positive control ((+)-catechin) and negative control (salicylic acid) were performed with the approach to verify its specificity and reproducibility. Subsequently, the developed system was applied to the screening and identification of α-glucosidase inhibitors from Polygonatum odoratum. Five phenethyl cinnamides (N-cis-feruloyloctopamine, N-trans-p-coumaroyloctopamine, N-trans-feruloyloctopamine, N-trans-p-coumaroyltyramine and N-trans-feruloyltyramine) and four homoisoflavanones ((3R)-5,7-dihydroxyl-3- (2',4'-dihydroxylbenzyl)-chroman-4-one, (3R)-5,7-dihydroxyl-6-methyl-3-(4'-hydroxylbenzyl) -chroman-4-one, (3R)-5,7-dihydroxyl-6-methyl-8-methoxyl-3-(4'-hydroxylbenzyl)-chroman-4-one and (3R)-5,7-dihydroxyl-6,8-dimethyl-3-(4'-hydroxylbenzyl)-chroman-4-one) with α-glucosidase inhibitory activities were identified. The results were in accordance with those of ultrafiltration screening. With the online system developed, here we present a feasible, selective and effective strategy for the rapid screening and identification of enzyme inhibitors from complex mixtures.

Key words: α-glucosidase, affinity solid-phase extraction (ASE), Chinese medicines, high performance liquid chromatography (HPLC), homoisoflavanone, phenethyl cinnamide