Iron Chelation by the Powerful Antioxidant Flavonoid Quercetin

Abstract

Chelation of the bare and hydrated iron(II) cation by quercetin has been investigated at the DF/B3LYP level in the gas phase. Several complexed species arising from neutral and anionic forms of the ligand have been taken into account. Both 1:1 and 1:2 metal/flavonoid stoichiometries have been considered. Results indicate that among the potential sites of chelation present on quercetin, the oxygen atoms belonging to the 3-hydroxy and 4-oxo, and to the 5-hydroxy and 4-oxo groups, are the preferred ones. Time-dependent density functional theory (TDDFT) calculations, used to reproduce the electronic UV−vis spectra of isolated quercetin and its complexes with Fe²⁺, were also performed in methanol and dimethylsulfoxide. Keywords: Quercetin; iron(II); complexation; antioxidants