Differentiation of flavonoid glycoside isomers by using metal complexation and electrospray ionization mass spectrometry.
The elucidation of flavonoid isomers is accomplished by electrospray ionization tandem mass spectrometry (ESI-MS/MS) via formation and collisional activated dissociation (CAD) of metal/flavonoid complexes containing an auxiliary ligand. Addition of a metal salt and a suitable neutral auxiliary ligand to flavonoids in solution results in the formation of [M(II) (flavonoid-H) ligand]+ complexes by ESI which, upon collisional activated dissociation, often result in more distinctive fragmentation patterns than observed for conventional protonated or deprotonated flavonoids. Previously, 2,2'-bipyridine was used as an auxiliary ligand, and now we compare and explore the use of alternative pyridyl ligands, including 4,7-diphenyl-1,10-phenanthroline. Using this technique, three groups of flavonoid glycoside isomers are differentiated, including glycosides of apigenin, quercetin, and luteolin.
Pikulski
Michael
M
Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712-0165, USA.
Brodbelt
Jennifer S
JS
D015082:2,2'-Dipyridyl / Q000737:chemistry; D002240:Carbohydrate Sequence; D003035:Cobalt / Q000737:chemistry; D007887:Fabaceae / Q000737:chemistry; D005419:Flavonoids / Q000737:chemistry*; D005638:Fruit / Q000737:chemistry; D007202:Indicators and Reagents; D008670:Metals / Q000737:chemistry*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010618:Phenanthrolines; D021241:Spectrometry, Mass, Electrospray Ionization; D014675:Vegetables / Q000737:chemistry
D005419:Flavonoids; D007202:Indicators and Reagents; D008670:Metals; D010618:Phenanthrolines; D003035:Cobalt; C002850:4,7-diphenylphenanthroline sulfonate; D015082:2,2'-Dipyridyl