Étude de l'activité antioxydante des extraits de plantes utilisées en médecines traditionnelles.

Abstract

Within the framework of the valorization of Algerian plant species, and their therapeutic virtues. This work as follow-up of the determinition of secondary metabolites and bioactivities, aims to quantify tannins (hydrolysable and condensed) and assess the antioxydant power by the following methods: total antioxidant activity, metal chelation, and iron reducing power by two methods for ethyl acetate and methanolic extracts of six Algerian species: Nonea vesicaria, Solenanthus lanatus, Cynoglossum cheirifolium, Olea europaea subsp. laperrinei, Rhus pentaphylla and Clematis cirrhosa. The results obtained show that R. pentaphylla has a high content of hydrolysable tannins for the ethyl acetate extract with a value of 898,64 ± 46,01 mg tannic acid equivalent / g dry extract and condensed tannins for the methanol extract with a value of 32,69 ± 2,63 mg catechin equivalent / g dry extract. In addition, the results of the antioxidant activity study showed that ethyl acetate and methanol extracts from O. europaea subsp. laperrinei had the highest total antioxidant capacity (780,81± 27,72 and 478,92 ± 19,66 mg ascorbic acid equivalent/g dry extract respectively). The ethyl acetate extract from C.cirrhosa showed a high iron chelation capacity with an IC50 of 762,45 ± 175,31 μg/ml, of which EDTA has the highest iron chelation capacity due to its low IC50 (3,92 ± 0,05 μg/ml). The two tests FRAP and reducing power activity confirmed that extracts of O. europaea subsp. laperrinei have excellent iron-reducing activity. For the FRAP test the methanol extract has a low EC1 (67,93 ± 1,46 μg/ml) and for the reducing power activity test the ethyl acetate extract of O. europaea subsp. laperrinei has a lower EC50 (85,84 ± 6,68 μg/ml) than the positive control trolox (110,10 ± 3,03 μg/ml). Finally, extracts with a high tannin contents and antioxidant activities can find applications in the pharmaceutical and food industry.