Quercetin is a substrate for the transmembrane oxidoreductase Dcytb

Evangelia Vlachodimitropoulou, Richard J. Naftalin, Paul A. Sharp

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)


Duodenal cytochrome b (Dcytb) is a transmembrane oxidoreductase protein found in apical membranes of duodenal enterocytes, as well as human erythrocytes, with the capacity to transport electrons donated by cytosolic ascorbate to extracellular electron receptors such as Fe(III), dehydroascorbate, or molecular O-2. We have investigated the capacity of the flavonoid quercetin to act as an electron donor for Dcytb in a manner similar to that of ascorbate by observing the reduction of extracellular Fe(III) to Fe(II) in either Madin-Darby canine kidney (MDCK) cells overexpressing Dcytb (Dcytb(+)) or Dcytb-null MDCK cells. In Dcytb(+) cells there is a saturable increase in extracellular Fe(III) reduction in response to increasing intracellular quercetin concentrations (K-m = 6.53 +/- 1.57 mu M), in addition to a small linear response, whereas in Dcytb-null cells there is only a small linear increase in extracellular Fe(III) reduction. No extracellular Fe(III) reduction occurs in Dcytb-null cells when the cells are preloaded with ascorbate. Flavonoids such as quercetin at their physiological concentrations can therefore function as modulators of ferric reductases, enhancing the import of Fe(II) and also providing extracellular reducing potential. (C) 2010 Elsevier Inc. All rights reserved.
Original languageEnglish
Pages (from-to)1366 - 1369
Number of pages4
JournalFree Radical Biology and Medicine
Issue number10
Publication statusPublished - May 2010


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