Comparison of the Antimicrobial and Antioxidant Effects of Oleuropein Extracted from Arbequina Olive Leaves with the Extracts of its Leaf and Fruit

Introduction: Olive leaf is an evergreen plant and enriched in phenolic compounds and antioxidants. Oleuropein is the most common type of phenolic compounds can found in Olive leaves. The aim of this study was to compare the antimicrobial and antioxidant effects of Oleuropein extracted from olive leaf with the extracts from its leaf and fruit. Methods: The type of study was experimental and after ethanol extraction from olive leaf and fruit, oleuropein was isolated from the leaf extract. Antimicrobial effects of Oleuropein obtained from olive fruit and leaf extracts against Staphylococcus saprophyticus and Pseudomonas aeruginosa bacteria were determined using minimum inhibitory concentration (MIC) method. Amounts of phenolic compounds were derived by the Folin-Ciocalteu assay and the antioxidant effects were determined by the 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) free radical inhibition method. SPSS version 16 software was used for statistical calculations, Excel program used to draw graphs and one-way ANOVA was used to evaluate the effect of the intervention. Results: Oleuropein was extracted from olive leaf in the amount of 14% with a purity of 70%. The highest and lowest amount of phenolic compounds and the antimicrobial and antioxidant effects were observed for Oleuropein obtained from olive leaf and olive fruit extracts, respectively. The amount of oleuropein phenolic compounds was equal to 879.16 (µg GAE/g), its MIC against S. saprophyticus and P.aeruginosa bacteria was equal to 3.25 and 12.5 mg/ml, respectively. Its antioxidant activity was equal to 8.59 µg/ml. Conclusion: In the present study, oleuropein was extracted from olive leaves and the study showed that the amount of oleuropein in the Spanish Arbican variety was obtained with the highest value of 14%. According to the results of antimicrobial activity and antioxidant, it can be concluded that olive leaf extract and extracted oleuropein have the potential to increase and improve the performance of preservatives and antioxidants.