Phenolic Compounds in Olive Leaf Extract as a Source of Useful Antioxidants

Abstract

Using electron paramagnetic resonance (EPR) spectroscopy, antioxidant properties of olive leaves extracts obtained of three autochthonous olive varieties grown in Istria, Buža, Istarska bjelica and Rosinjola have been investigated. The highest content of total phenolic compounds ((57.6 ± 0.1) mg quercetin equivalents/g of dry extract) was obtained for extract of Buža. The analysis of chemical composition of extracts was performed by HPLC/DAD and LC/MS method. Futhermore, Buža has shown the highest antioxidant activity in scavenging DPPH radical (AA=80.0 ± 3.0%), followed by extracts of Rosinjola and Istarska bjelica. In DPPH radical scavenging assay fi nal concentration of extracts in was 0.1 mg/mL. Antioxidant activity was in good correlation with total phenolics. It seems that these bioproducts could be useful in therapy of conditions related with oxidative stress. The results have indicated a high potential of application of olive leaf and olive leaf extract in foodstuff and food additive. Also, it can be used to improve the shelf life of foods and to develop functional foods