Phytochemical analysis and alpha-amylase inhibitory property of olive (Olea europaea L.) leaves extracts

Evaluation of medicinal plants for their antidiabetic activities has increased considerably around the world as well as in Algeria. Olea europaea, commonly called Zeytoune, is traditionally used by Tlemcen population in Algeria, for treating diabetes mellitus. In this work, we evaluate the capacity of O. europaea leaves crude extracts to inhibit in vitro α-amylase activity. The qualitative phytochemical screening carried out on O. europaea 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 802.57 ± 0.001 mg GAE/ g and 359 ± 0.002 mg CE/ g, respectively. In vitro tests carried out on the inhibitory of α-amylase activity, revealed an inhibitory effects, specifically with hydroacetonic extract in a concentration-dependent manner, with an IC50 value of 0.27 ± 0.02 mg/mL. These findings reveals that O. europaea leaves extracts could represent an interesting source of bioactive compounds and allow to the development of new antidiabetic agents.