title: Putative identification of new p-coumaroyl glycoside flavonoids in grape by ultra-high performance liquid chromatography/high-resolution mass spectrometry.
abstract: BACKGROUND
  Grape polyphenols are antioxidant compounds, markers in vine chemotaxonomy, and involved in color stabilization of red wines. Sugar acylation usually confers higher stability on glycoside derivatives and this effect is enhanced by an aromatic substituent such as p-coumaric acid. Until now, only p-coumaroyl anthocyanins have been found in grape.
  
  
  METHODS
  A method of 'suspect screening analysis' by ultra-high-performance liquid chromatography/high-resolution mass spectrometry (UHPLC/QTOFMS) has recently been developed to study grape metabolomics. In the present study, this approach was used to identify new polyphenols in grape by accurate mass measurement, MS/MS fragmentation, and study of correlations between fragments observed and putative structures.
  
  
  RESULTS
  Three putative p-coumaroyl flavonoids were identified in Raboso Piave grape extract: a dihydrokaempferide-3-O-p-coumaroylhexoside-like flavanone, isorhamnetin-3-O-p-coumaroylglucoside, and a chrysoeriol-p-coumaroylhexoside-like flavone. Accurate MS provided structural characterization of functional groups, and literature data indicates their probable position in the molecule. A fragmentation scheme is proposed for each compound.
  
  
  CONCLUSIONS
  Compounds were identified by overlapping various analytical methods according to recommendations in the MS-based metabolomics literature. Stereochemistry and the definitive position of substituents in the molecule can only be confirmed by isolation and characterization or synthesis of each compound. These findings suggest addressing research of acylated polyphenol glycosides to other grape varieties.
authors.affiliation: Consiglio per la Ricerca e la Sperimentazione in Agricoltura - Centro di Ricerca per la Viticoltura (CRA-VIT), Viale XXVIII aprile 26, 31015, Conegliano (TV), Italy.
authors.forename: Annarita
authors.initials: A
authors.lastname: Panighel
authors.affiliation: Consiglio per la Ricerca e la Sperimentazione in Agricoltura - Centro di Ricerca per la Viticoltura (CRA-VIT), Viale XXVIII aprile 26, 31015, Conegliano (TV), Italy.
authors.forename: Mirko
authors.initials: M
authors.lastname: De Rosso
authors.affiliation: Consiglio per la Ricerca e la Sperimentazione in Agricoltura - Centro di Ricerca per la Viticoltura (CRA-VIT), Viale XXVIII aprile 26, 31015, Conegliano (TV), Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Dalla Vedova
authors.affiliation: Consiglio per la Ricerca e la Sperimentazione in Agricoltura - Centro di Ricerca per la Viticoltura (CRA-VIT), Viale XXVIII aprile 26, 31015, Conegliano (TV), Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Flamini
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003373:Coumaric Acids / Q000032:analysis; D005419:Flavonoids / Q000032:analysis*; D006027:Glycosides / Q000032:analysis*; D059808:Polyphenols / Q000032:analysis; D011422:Propionates; D053719:Tandem Mass Spectrometry / Q000379:methods*; D027843:Vitis / Q000737:chemistry*
chemical_list: D003373:Coumaric Acids; D005419:Flavonoids; D006027:Glycosides; D059808:Polyphenols; D011422:Propionates; C495469:p-coumaric acid