Structural characterization of flavonol 3,7‐di‐O‐glycosides and determination of the glycosylation position by using negative ion electrospray ionization tandem mass spectrometry

Abstract

Flavonol 3,7-di-O-glycosides were investigated by negative ion electrospray ionization tandem mass spectrometry using a quadrupole linear ion trap (LIT) mass spectrometer. The results indicate that the fragmentation behavior of flavonol 3,7-di-O-glycosides is substantially different from that of their isomeric mono-O-diglycosides. In order to characterize a flavonoid as a flavonol 3,7-di-O-glycoside, both [Y3(0) - H]-* and [Y(0) - 2H]- ions should be present in [M - H]- product ion spectrum. The MS(3) product ion spectra of Y3(0)-, [Y3(0) - H]-* and Y7(0)- ions generated from the [M - H]- ion provide sufficient structural information for the determination of glycosylation position. Furthermore, the glycosylation positions are determined by comparing the relative abundances of Y3(0)- and Y7(0)- ions and their specific fragmentation patterns with those of flavonol mono-O-glycosides. In addition, a [Y3(0) - H]-* ion formed by the homolytic cleavage of 3-O glycosidic bond with high abundance points to 3-O glycosylation, while a [Y(0) - 2H]- ion formed by the elimination of the two sugar residues is consistent with glycosylation at both the 3-O and 7-O positions. Investigation of negative ion ESI-MS(2) and MS(3) spectra of flavonol O-glycosides allows their rapid characterization as flavonol 3,7-di-O-glycoside and their differentiation from isomeric mono-O-diglycosides, and also enables their direct analysis in crude plant extracts.

Chemical Fingerprinting of Medicinal Plants “Gui-jiu” by LC-ESI Multiple-Stage MS

“…Since the shoulder absorption of these flavonoids is characteristically different from the podophyllotoxin-type lignans, the use of a wavelength above 300 nm is preferred in the analysis of the flavonoids. Compounds (8) and (11) [36]. Therefore, peaks 2 and 3 are proposed to be quercetin-3-O-glucopyranoside and kaemferol-3-O-glucopyranoside, which have previously been isolated from S. emodi [37].…”

A study of characteristic fragmentation of isoflavonoids by using negative ion ESI‐MSn

“…[20 -24] Previous research revealed that the formation of the aglycone ion (Y 0 − ) and the radical aglycone ion ([Y 0 − H] −• ) plays a significant role in the structural elucidation and differentiation of flavonoid O-glycoside isomers. [20,21] The formation of [Y 0 − H] −• ion has been determined from the product ion spectrum of genistein 7-O-glucoside using time-of-flight MS at high mass resolution. [22] However, there have been few systematic investigations on the characteristic fragmentation of a group of isoflavonoids using tandem mass spectrometric techniques (MS/MS).…”

Kaempferol Glycosides from Lobularia maritima and Their Potential Role in Plant Interactions

“…MS/MS Analysis for the structural characterization of glycosyl flavonoids has been recently reviewed [15] [16].…”