Commercial and laboratory extracts from Olea europaea L. leaf: estimation of oleuropein content

Olea europaea L. leaves, a typical herbal drug in the Mediterranean regions, have been widely used in traditional remedies in countries such as Greece, Spain, Italy, France, Turkey, Israel, Morocco, and Tunisia. They have been used in the human diet as an extract, an herbal tea, and a powder, and they contain many potentially bioactive compounds that may have antioxidant, antihypertensive, antiatherogenic, anti-inflammatory, hypoglycemic, and hypocholesterolemic properties. One of these potentially bioactive compounds is the secoiridoid, oleuropein, which can constitute up to 6-9% of dry matter in the leaves, it and its derivatives exhibit several specific biological activities [1, 2, 3]. Other bioactive components found in olive leaves include related secoiridoids, flavonoids, and triterpenes. The aim of the present work is the HPLC/DAD/MS is the characterization and quantification of antioxidant secondary metabolites in olea leaves and evaluate the oleuropein content and antiradical activities in commercial acqueous Olea leaf extracts, recently used to the preparation of antioxidant and antihypertensive dietary supplements. Commercial extracts were homogenized, centrifuged and analyzed; laboratory extracts were prepared extracting fresh or dried leaves, coming from different Italian and European cultivar, for 1 hour at 70°C and then for 12 hours at room temperature. In the commercial samples the concentration of oleuropein found was from trace amounts to 1061 mg/L, of extract; in the leaf saples was from 8.71 mg/g to 29.65 mg/g of leaves.