Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 64843
Title Peroxidase-catalyzed formation of quercetin quinone methide-glutathione adducts
Author(s) Awad, H.M.; Boersma, M.G.; Vervoort, J.; Rietjens, I.M.C.M.
Source Archives of Biochemistry and Biophysics X (2000)378. - ISSN 0003-9861 - p. 224 - 233.
Department(s) Biochemistry
Publication type Refereed Article in a scientific journal
Publication year 2000
Abstract The oxidation of quercetin by horseradish peroxidase/H2O2 was studied in the absence but especially also in the presence of glutathione (GSH). HPLC analysis of the reaction products formed in the absence of GSH revealed formation of at least 20 different products, a result in line with other studies reporting the peroxidase-mediated oxidation of flavonoids. In the presence of GSH, however, these products were no longer observed and formation of two major new products was detected. 1H NMR identified these two products as 6-glutathionylquercetin and 8-glutathionylquercetin, representing glutathione adducts originating from glutathione conjugation at the A ring instead of at the B ring of quercetin. Glutathione addition at positions 6 and 8 of the A ring can best be explained by taking into consideration a further oxidation of the quercetin semiquinone, initially formed by the HRP-mediated one-electron oxidation, to give the o-quinone, followed by the isomerization of the o-quinone to its p-quinone methide isomer. All together, the results of the present study provide evidence for a reaction chemistry of quercetin semiquinones with horseradish peroxidase/H2O2 and GSH ultimately leading to adduct formation instead of to preferential GSH-mediated chemical reduction to regenerate the parent flavonoid
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