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Analysis of oxidized epigallocatechin gallate by liquid chromatography/mass spectrometry
Author(s) -
Mizooku Yasuo,
Yoshikawa Muneyoshi,
Tsuneyoshi Toshihiro,
Arakawa Ryuichi
Publication year - 2003
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1135
Subject(s) - chemistry , gallate , electrospray ionization , chromatography , epigallocatechin gallate , mass spectrometry , aqueous solution , tandem mass spectrometry , moiety , catechin , liquid chromatography–mass spectrometry , nuclear chemistry , organic chemistry , polyphenol , antioxidant
Abstract (−)‐Epigallocatechin gallate (EGCG) of catechins changes from non‐colored at around neutral pH to yellow at higher pH region in aqueous solution. The pH‐dependent oxidation of EGCG was analyzed by liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS). LC/MS/MS analysis of EGCG and its related compounds, (−)‐epicatechin gallate (ECG) and (−)‐epigallocatechin (EGC), successfully elucidated the structure relationship of EGCG solution involving the color change reaction at different pH conditions. The oxidation species produced at alkaline pH was detected at a different retention time from EGCG in the chromatograms of the EGCG sample. The oxidation species was found to correspond to M+14 (where M is the molecular weight of EGCG), which has two hydrogen atoms removed and addition of one oxygen atom to the gallyl moiety in the B‐ring of EGCG. Copyright © 2003 John Wiley & Sons, Ltd.