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Identification of isomeric flavonoid glucuronides in urine and plasma by metal complexation and LC‐ESI‐MS/MS
Author(s) -
Davis Barry D.,
Needs Paul W.,
Kroon Paul A.,
Brodbelt Jennifer S.
Publication year - 2006
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.1050
Subject(s) - chemistry , glucuronide , naringenin , chromatography , flavonoid , electrospray ionization , tandem mass spectrometry , mass spectrometry , metabolite , electrospray , glucuronidation , stereochemistry , organic chemistry , biochemistry , enzyme , antioxidant , microsome
Noncovalent complexes were used for structural determination and isomer differentiation of flavonoid glucuronides. Several flavonoid glucuronides including naringenin‐7‐ O ‐glucuronide, synthesized here for the first time, were used as test compounds. Electrospray ionization quadrupole ion trap mass spectrometry with collision‐induced dissociation (CID) was used to analyze complexes of the form [Co(II) (L‐H) (Aux)] + and [Co(II) (L‐H) (Aux) 2 ] + , in which L is the flavonoid glucuronide and Aux is a phenanthroline‐based ligand. These complexes yielded characteristic fragmentation patterns that facilitated assignment of the substitution position of the glucuronides. The methods were adapted to liquid chromatography/tandem mass spectrometry (LC‐MS/MS) with postcolumn cobalt complexation and were tested on extracts from biological fluids. The metabolites naringenin‐7‐ O ‐glucuronide and naringenin‐4′‐ O ‐glucuronide were detected in human urine following the consumption of grapefruit juice. Isomeric quercetin glucuronides were identified and differentiated after spiking rat plasma at the 1 µ M level, proving that the new methods are effective at biologically relevant concentrations. Copyright © 2006 John Wiley & Sons, Ltd.