Complexing behavior of rutin and quercetin

The equilibrium reactions between rutin, 3-[6-O-(6-deoxy-α-L-mannopyranosyl)-(β-D-glucopyranosyl)oxy]-2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4H-1-benzopyran-4-one, and quercetin (rutin aglycone) with iron(III), copper(II), cobalt(II), and nickel(II) have been studied by potentiometric and spectrophotometric methods in aqueous solution. All measurements were carried out at t = 20 °C and μ = 0.10 M, and the corresponding stability constants were calculated by applying computational methods. The interactions between the proposed cations with both biological ligands and other related ones are compared, with simultaneous postulation of the probable structures. Key words: chelate stability constants of rutin, chelate stability constants of quercetin, transition metal ion interaction with flavonoids, stability constant determinations, potentiometric and spectrophotometric studies.