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.

Determination of polyphenolic components by High Performance Liquid Chromatography (HPLC) and evaluation of the antioxidant activity of leaves of Olea europaea L. var. sylvestris (Miller) Lehr

“…« These results are in agreement with those of Addab [7] who showed a relatively high anti-radical power of the hydroethanolic extract of Oleaster leaves vis-à-vis DPPH close to that of vitamin C with CI50 of 84.74±1.16 mg/ ml, and 32.60±0.98 respectively ». « According to studies conducted by Mezouar [8] and Djenane [5], hydromethanolic extracts of wild olive leaves exhibit significant antioxidant activity with CI 50 of 13.14±0.16μg/ml and 19.2±1.6μg/ml respectively ». « Similarly Makowska-Wąsshowed a high free radical scavenging capacity with IC50 of 62.48±3.7 μg/ml for Oleaster leaf methanolic extract.…”