Activités antioxydante et anticoagulante des polyphénols de la pulpe d’olive Olea europaea L.

Abstract

The objective of this study is the evaluation of antioxidant and anticoagulant activities of polyphenols obtained from extracts of olive pulp(Olea europaea L.) of two varieties cultivated in Setif. The Pomological characterization for the two varieties studied showed a difference between them in terms of weight, width, length, humidity and oil content and its polyphenol content. Quantitative analysis of extracts revealed a wealth of olives by polyphenols and flavonoids, but the content in flavonoids is low compared to that of polyphenols for both studied varieties. Qualitative analysis of two polyphenolic extracts by TLC revealed the presence of numerous constituents, including oleuropein, tyrosol, catechin, rutin, quercitin, vanillin and gallic acid. The antioxidant capacity of this polyphenolic extract was evaluated in vitro by three different tests: DPPH• free radical scavenging assay, ß-carotene bleaching test and reducing power assay. The extract demonstrated a great capacity to scavenge the DPPH• radical with an IC50 equal to 2.585 and 4.625 µg/ml for the variety Bouchouk extract and for the variety Knanfes extract, respectively. This antioxidant capacity is confirmed by the ß-carotene bleaching assay and the reducing power test. Indeed, theses extracts are also able to inhibit lipid peroxydation with respectable percentages of about 97. 27 % for the extract of Bouchouk variety and 94.45% for the extract of Khanfes variety and they have a great reducing power with an EC50 of 5.055 and 6.110 µg/ml respectively. The anticoagulant activity of olive polyphenols was also evaluated in vitro by using two tests: the test of the cephalin-kaolin time and the test of Quick time.The times of coagulation obtained on normal plasma in the presence of these polyphenols indicate that they carry an anticoagulant activity on the two pathways of coagulation but this activity is highly marked on the endogenous pathway than on the exogenous pathway.