title: Electrospray ionization and collision-induced dissociation tandem mass spectrometric discrimination of polyphenolic glycosides: exact acylation site determination of the O-acylated monosaccharide residues.
abstract: BACKGROUND
  Acylated monosaccharide residues are structural subunits of natural products or synthetic intermediates that have received much attention in past years. Determination of the acylation sites of these residues still relies heavily on the comparison of their characteristic NMR signals with those of known standards and synthesized acylated glycosides. It is important to develop a rapid analytical method for determining the acylation sites for these compounds, and this is described in this study.
  
  
  METHODS
  Six known polyphenolic glycosides were used for the electrospray ionization and collision-induced dissociation tandem mass spectrometry (ESI-CID-MS/MS) discrimination of the acylated monosaccharide residues with different acylation sites. A combination of ESI-CID-MS/MS, using a triple quadrupole mass spectrometer, with ultra-performance liquid chromatography (UPLC) and photo-diode array (PDA) detection (UPLC-PDA) has been applied to the identification or characterization of polyphenolic glycosides in Polygonum capitatum that possess an acylated monosaccharide residue.
  
  
  RESULTS
  An ESI-MS and CID-MS/MS method has been developed for the determination of the acylation sites of polyphenolic glycosides that possess an acylated monosaccharide residue. Twelve polyphenolic glycosides including four new ones have been identified or characterized in P. capitatum. Eight (including the new ones) of the twelve glycosides were reported for the first time from this plant.
  
  
  CONCLUSIONS
  The developed ESI-MS and CID-MS/MS method provided a very useful strategy for the determination of the sites of polyphenolic glycosides that possess an acylated monosaccharide residue. The acylation site could be determined by the characteristic product ion spectra of the in-source CID-generated O-acyl monosaccharide ion [B(1)](+). The presented work may facilitate the structural characterization of these types of compounds.
authors.affiliation: Provincial Key Laboratory of Pharmaceutics in Guizhou Province, School of Pharmacy, Guiyang Medical College, Guiyang, Guizhou, PR China. lshangg@163.com
authors.forename: Shang-Gao
authors.initials: SG
authors.lastname: Liao
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Zhang
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.forename: Fa
authors.initials: F
authors.lastname: Sun
authors.forename: Yong-Jun
authors.initials: YJ
authors.lastname: Li
authors.forename: Ai-Min
authors.initials: AM
authors.lastname: Wang
authors.forename: Yong
authors.initials: Y
authors.lastname: Huang
authors.forename: Yan-Yu
authors.initials: YY
authors.lastname: Lan
authors.forename: Yong-Lin
authors.initials: YL
authors.lastname: Wang
mesh_terms: D000215:Acylation; D005707:Gallic Acid / Q000737:chemistry; D006027:Glycosides / Q000737:chemistry*; D009005:Monosaccharides / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry; D028502:Polygonum / Q000737:chemistry; D011794:Quercetin / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D006027:Glycosides; D009005:Monosaccharides; D010636:Phenols; D010936:Plant Extracts; D005707:Gallic Acid; D011794:Quercetin