These authors equally contributed to this work.
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Identification of autoxidation oligomers of flavan-3-ols in model solutions by HPLC-MS/MS
Article first published online: 3 DEC 2008
DOI: 10.1002/jms.1536
Copyright © 2008 John Wiley & Sons, Ltd.
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How to Cite
He, F., Pan, Q.-H., Shi, Y., Zhang, X.-T. and Duan, C.-Q. (2009), Identification of autoxidation oligomers of flavan-3-ols in model solutions by HPLC-MS/MS. J. Mass Spectrom., 44: 633–640. doi: 10.1002/jms.1536
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These authors equally contributed to this work.
Publication History
- Issue published online: 11 MAY 2009
- Article first published online: 3 DEC 2008
- Manuscript Accepted: 28 OCT 2008
- Manuscript Received: 4 JUL 2008
Funded by
- National Natural Science Foundation of China. Grant Number: 30671467 to C.-Q.D
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Keywords:
- HPLC-DAD-ESI/MS;
- flavan-3-ols;
- autoxidation;
- B-type dehydrodicatechin;
- B-type dehydrotricatechin;
- A-type dehydrotricatechin
Abstract
Autoxidation of flavan-3-ols was carried out in aqueous/methanol model solutions under mildly acidic conditions (pH 6.0), and these autoxidation products were analyzed by using high performance liquid chromatography (HPLC) coupled with tandem mass spectrometry (MS/MS). The results showed that (+)-catechins and (−)-epicatechins generated autoxidation reaction with each other to form a series of oligomers that had the same [M − H]− molecular ions (MS1) as those of natural procyanidins, but had completely different fragment ions (MS2). According to MS/MS analysis, the major fragments of these oligomers were derived not only from the retro-Diels–Alder (RDA) dissociations on the C-rings of the flavan-3-ol units, but also from the quinone-methide (QM) cleavage of the interflavan linkages (IFL), and thus they were identified as B-type dehydrodicatechins, B-type dehydrotricatechins and A-type dehydrotricatechins, respectively. The potential structures of their [M − H]− molecular ions and partial fragment ions were deduced on the basis of the MS/MS characterization and the oxidation of flavan-3-ols in previous reports. Some specific fragment ions were found to be very useful for identifying the autoxidation oligomers (the B-type dehydrodicatechins at m/z 393, the B-type dehydrotricatechins at m/z 681 and the A-type dehydrotricatechins at m/z 725). Copyright © 2008 John Wiley & Sons, Ltd.