Determination of antioxidant properties of lyophilized olive leaf water extracts obtained from 21 different cultivars

The objective of this study was to compare the antioxidant activities of lyophilized olive leaf water extracts (OLWExtracts) from 21 different olive tree cultivars. The highest total phenolic content (102.69 +/- 1.63 mu g GAE/mg extract) was found in cultivar 'Esek Zeytini' and the lowest content (78.52 +/- 2.18 mu g GAE/mg extract) was in 'Uslu'. The highest total flavonoid content (12.47 +/- 0.12 mu g QE/mg extract) obtained from 'Frantoio'. According to EC50 values, 'Domat' have the highest DPPH scavenging activity (EC50 =59 mu g/mL), reducing power (EC50 =180 mu g/mL), and superoxide radical scavenging capacity (EC50=44 mu g/mL). While, 'Ascolana' showed the highest metal chelating capacity (EC50=163 mu g/mL), 'Memecik' showed the highest hydrogen peroxide (H2O2) scavenging capacity. Research results exhibited that OLWExtracts are comparable to synthetic antioxidants. The correlation study showed that while total phenolic content correlated with DPPH scavenging activity and reducing power (p < 0.01), total flavonoid content correlated with metal chelating and superoxide radical scavenging capacity (p < 0.05)