Quercetin as a shuttle for labile iron

The antioxidant activity of flavonoids may involve their ability to complex body iron in non-redox-active forms. In this study, it was found that the catechol flavonoids rutin and quercetin are able to suppress redox-active labile plasma iron (LPI) in both buffered solution and in iron-overloaded sera. Both flavonoids are effective in loading the metal into the iron-transport protein transferrin. Iron derivatives of quercetin and rutin are able to permeate cell membranes, however, only free quercetin is able to gain access to the cytosol and decrease intracellular labile iron pools. These results suggest that the antioxidant activity of quercetin may be dependent on its ability to shuttle labile iron from cell compartments followed by its transfer to transferrin.

Graphical abstractQuercetin may remove labile iron from iron-overloaded cells and transfer it without generating oxidative stress to other high-affinity molecules (e.g., transferrin).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Catechol flavonoids rutin and quercetin decrease labile iron in plasma and solution. ► They also transfer iron to high the affinity molecules transferrin and calcein. ► Quercetin (but not rutin) can decrease intracellular labile iron pools. ► Quercetin may be used in iron-redistribution therapy.