Tailoring flavonoids antioxidant properties through covalent immobilization into dual stimuli responsive polymers

With the aim to modulate the flavonoid antioxidant properties, catechin and quercetin were covalently inserted into hydrogel networks by free radical grafting procedure. The effective conjugation of both flavonoids into the polymer chains was checked by FT-IR analyses. Water uptake measurements and calorimetric analyses proved the pH-and thermo-responsiveness. The effect of temperature on antioxidant properties were evaluated as scavenging ability and redox performance, while the determination of the ability to preserve folic acid from UV degradation proved the pH responsiveness. Data show that the matrices are more effective in the swollen than in the shrunken state.