Cinétique d'étude de l'activité antioxydante d'un extrait aqueux de calices séchés <em>d'Hibiscus</em> <em>Sabdariffa</em> par piégeage de l'ion radicalaire ABTS<sup>•+</sup>

Abstract

The anti-radical and therefore antioxidant activities of different concentrations of dried calyxes of Hibiscus sabdariffa dried calyx "sorrel" and that of a reference antioxidant, "gallic acid", were determined by the scavenging effects on free radical cation of 2,2'-azinobis[3-ethylbenzothiazoline-6sulfonate] (ABTS + ) according to the experimental method of Re et al. after a time reaction of 1, 6 10 and 12 minutes. The aim of this study was to determine the incubation time required for maximum antioxidant activity. The obtained results shown that the of Hibiscus sabdariffa dried calyxes, as those of gallic acid have a maximum activity after 1 minute of incubation time. This activity would increase ranging 3 to 20% depending the tested concentrations after 1 to 6 minutes of incubation. And, between 1 to 5% after 10 to 12 minutes. The Sorrel dried calyxes keep their antioxidant activity despite the drying heating process (drying). The incubation times of 6 or 10 minutes appear to be the optimum reaction time to evaluate the antioxidant activity according to the ABTS method.