Alpha-amylase inhibitory activity and antioxidant effect of Olea var. europaea sylvestris leaves extracts.

Abstract

Evaluation of medicinal plants for their antidiabetic activities has increased considerably around the world as well as in Algeria. Olea europaea var. sylvestris, commonly called Ezzeboudj, is traditionally used by Tlemcen population in Algeria, for treating diabetes mellitus. In this work, we studied the antioxidant activity of wild olive leaves crude extracts, by free radical DPPH scavenging method and iron reduction FRAP. On the other hand, evaluation of the ability of the extracts to inhibit α-amylase activity. The qualitative phytochemical screening carried out on O. europaea var. sylvestris leaves extracts showed the presence of tannins, sterols and triterpenes, saponins, flavonoids and terpenoids. A quantitative analysis of the crude extracts showed significant levels of total polyphenols and flavonoids in hydroacetonic extract, with an amount of 228,45 ± 0,03 mg GAE /g and 204,8 ± 0,04 mg CE /g, respectively. The results obtained from the antioxidant activity showed a high scavenging activity for hydroacetonic extract with an IC50 of 7,95 ± 0,16 µg/ml. In vitro tests carried out on the inhibitory of α-amylase activity, revealed an inhibitory effects, specifically with hydromethanolic extract in a concetration-dependent manner, with an IC50 value of 0,91 ± 0,02 mg/ml. These findings reveals that O. europaea var. sylvestris leaves could represent an interesting source of antioxidants and allow to the development of new antidiabetic agents.