Ultra-performance LC-photodiode array-eÎ-ESI-MS/MS screening method for the detection of radical-scavenging natural antioxidants from Radix et Rhizoma Rhei

Abstract

A novel ultra-performance LC-photodiode array-eÎ-ESI-MS/MS screening method was developed for the detection and identification of natural antioxidants from Radix et Rhizoma Rhei. Nine compounds were found to possess a potential antioxidant activity, and their free radical-scavenging capacities were investigated in detail. The nine compounds were identified as 1-O-galloyl-2-O-cinnamoylglucose, 6-hydroxymusizin-8-O-β-D-glucopyranoside, (+)-catechin, gallic acid 3-O-β-D-glucopyranoside, trans-3,5,4′- trihydroxystilbene-4′-O-β-D-(2″-O-galloyl)-glucopyranoside, sennoside A, 4-(4′-hydroxyphenyl)-2-butanone-4′-O-β-D- (2″-O-galloyl-6″-O-p-coumaroyl) glucopyranoside, emodin-8-O-(6″-O-malonyl) glucopyranoside, and physcion-8-O-β-D- glucopyranoside. The reactivity and SC50 values of those compounds were investigated, respectively. 1-O-Galloyl-2-O-cinnamoylglucose showed the strongest capability for scavenging 1,1-diphenyl-2-picrylhydrazyl-free radical; trans-3,5,4′-trihydroxystilbene-4′-O-β-D-(2″-O-galloyl) glucopyranoside showed the strongest capability for scavenging superoxide radical; 4-(4′-hydroxyphenyl)-2-butanone-4′-O-2-D-(2″-O- galloyl-6″-O-p-coumaroyl) glucopyranoside exhibited the highest reactivity in the lipid peroxidation processes. The use of the analytical screening method based on ultra-performance LC-photodiode array-eÎ-ESI-MS/MS would provide a new way for rapid detection of radical-scavenging natural compounds from Radix et Rhizoma Rhei or complex matrices. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.