617690-17-2Relevant academic research and scientific papers
Synthesis, electrochemical, spectral, and antioxidant properties of complexes of flavonoids with metal ions
De Souza, Rubens F. V.,Sussuchi, Eliana M.,De Giovani, Wagner F.
, p. 1125 - 1144 (2003)
Complexes of metal ions with the flavonoids quercetin (H2L 1), rutin (H2L2) and 3-hydroxyflavone (HL 3) have been synthesized. From the data obtained by elemental analyses, molar conductance, atomic absorption, thermal analyses, 1H NMR, IR, UV-Vis and EPR spectroscopies one can propose the compositions: [Cu2(L1)(H2O)4]Cl2 (1), [Cu3(L2)2(H2O)6]Cl 2 (2), [Cu(L3)(H2O)2]Cl (3), [Fe2 (L1)(H2O)8]Cl2 (4), [Fe3(L2)2(H2O)12]Cl 2 (5) and [Fe(L3)(H2O)4]Cl (6). We have used the assumption that the electrochemical oxidation can be used as a model for antioxidant activities for the flavonoids. The cyclic voltammograms show irreversible oxidation processes at +0.58 V and +0.91 V for (1), +0.82 V for (2), +0.89 V for (3), +0.58 V and +0.90 V for (4), +0.78 V for (5) and +0. 86 V for (6) versus Ag/AgCl. These values are lower than those for the free flavonoids indicating a more favorable antioxidant activity. Furthermore, these complexes were also more effective than the uncomplexed flavonoids scavenging superoxide radicals generated by reduction of the oxygen-saturated solution. The superoxide radical scavenging activities of flavonoid complexes seemed to correlate with the redox potentials of the flavonoid.
