Characterization of flavonoids by aluminum complexation and collisionally activated dissociation

Junmei Zhang, Junmei Wang, Jennifer S. Brodbelt

Research output: Contribution to journalArticle

41 Scopus citations

Abstract

Aluminum complexes of the type [AlIII (flavonoid - H) 2]+ are generated by electrospray ionization in order to allow differentiation of isomeric flavonoids by tandem mass spectrometry. The dominant species observed from the aluminum complexation reaction has a 1:2 aluminum(III): flavonoid stoichiometry. Differentiation of 18 flavonoids constituting seven isomeric series was achieved based on the collisionally activated dissociation patterns of the aluminum complexes. Characteristic fragmentation pathways allow identification of the site of glycosylation, the type of saccharide (rutinose versus neohesperidose) and the type of bond between the C-2 and C-3 atoms (thus distinguishing flavanones from flavonols and flavones). Two stable coordination geometries of the aluminum complex of apigenin were identified. The non-planar structure with a plane-angle of nearly 90° is 25.3 kcal mol-1 more favorable than the planar structure. The conformations of the complexes, which involve multiple interactions between the aglycone and disaccharide portions of the flavonoid with the metal ion, are significantly different for the isomeric flavonoids.

Original languageEnglish (US)
Pages (from-to)350-363
Number of pages14
JournalJournal of Mass Spectrometry
Volume40
Issue number3
DOIs
StatePublished - Mar 1 2005

Keywords

  • Aluminum complexation
  • Collisionally activated dissociation
  • Flavonoid diglycosides
  • Isomer differentiation
  • Molecular modeling

ASJC Scopus subject areas

  • Spectroscopy

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