Influence of Cultivar, Harvesting Season and Geographical Origin on Phenolic Content in Leaves of Greek Olive Cultivars

The influence of cultivar, harvesting season and geographical origin on the concentration of phenolic compounds and their antioxidant activity of 'Kalamata' and 'Konservolia' leaves have been studied. The leaves were collected from three different locations, the Agricultural University of Athens orchard, Rovies Evoias and Poros in June and October 2009. Total phenolic content and antioxidant activity of the samples were determined according to Folin-Ciocalteau and DPPH methods, respectively, while separation and identification of phenolic compounds was carried out by HPLC analysis. Total phenolic content for 'Kalamata' ranged between 1.92-3 mg GAE/g dry tissue and for 'Konservolia' between 1.9-2.51 mg GAE/g dry tissue, while the values for the antioxidant activity ranged between 133.15-567.7 mg/L for 'Kalamata' and 155.73-504.98 mg/L for 'Konservolia'. The HPLC analysis showed the presence of flavonoids, hydroxycinnamic derivatives and secoiridoids. The most abundant flavonoids were rutin, luteolin-7-o-glucoside and luteolin-4-o-glucoside while the most abundant secoiridoid and hydroxycinnamic derivative were eleuropein and p-coumaric acid, respectively.