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

✍ Scribed by Keyume Ablajan; Zeper Abliz; Xiao-Ya Shang; Jiu-Ming He; Rui-Ping Zhang; Jian-Gong Shi

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 423 KB
• Volume: 41
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/jms.995

✦ Synopsis

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 [Y^3^~0~ − H]^−•^ and [Y~0~ − 2H]^−^ ions should be present in [M − H]^−^ product ion spectrum. The MS^3^ product ion spectra of Y^3^~0~^−^, [Y^3^~0~ − H]^−•^ and Y^7^~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 Y^3^~0~^−^ and Y^7^~0~^−^ ions and their specific fragmentation patterns with those of flavonol mono‐O‐glycosides. In addition, a [Y^3^~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. Copyright © 2006 John Wiley & Sons, Ltd.