437 Influence of Cultivar, Harvesting Season and Geographical Origin on Phenolic Content in Leaves of Greek Olive Cultivars E. Giannakopoulou, G. Mitsopoulos and M. Hagidimitriou Pomology Laboratory Crop Science Department Agricultural University of Athens Iera Odos 75, 11855 Athens Greece V. Papageorgiouand M. Komaitis Food Chemistry and Analysis Laboratory Food Science and Technology Department Agricultural University of Athens Iera Odos 75, 11855 Athens Greece Keywords: olive, phenolic compounds, antioxidant activity Abstract 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. INTRODUCTION Olive culture is inextricably tied to the history and culture of Greece. Furthermore, olive oil and table olives are important parts of the Mediterranean diet, which is well known for its high content in phenolic compounds, plant secondary metabolites with great structural diversity. These compounds play an important role in the prevention of cardiovascular diseases and some types of cancer due to their antioxidant activity (Andrikopoulos et al., 2002). Olive leaves have also been used as a folk remedy to treat fever and some serious diseases such as malaria (Benavente-Garcia et al., 2005). The phenolic profile of olive trees depends on many factors, such as genotype, tissue type, developmental stage, geographical origin (Vinha et al., 2005). In the present study the total amount of phenolics and their antioxidant activity were studied in the leaves of ‘Kalamata’ and ‘Konservolia’ in two different harvesting seasons and in three different locations. MATERIALS AND METHODS The leaves were collected from ‘Kalamata’ ‘and ‘Konservolia’ cultivars in the second half of June and October 2009 from the Agricultural University of Athens (AUA) orchard, Rovies Evoias and Poros. The extraction of the phenolic compounds was carried out according to Ryan et al. (2002) protocol. Total phenolic content and antioxidant activity of the samples were determined according to Folin-Ciocalteau (Shahidi and Naczk, 1995) and DPPH (Molyneux, 2004) methods, respectively. The total phenolic content of the samples was expressed as milligrams of gallic acid equivalents (mg GAE) per gram of dried tissue, while antioxidant activity was expressed using the IC 50 index (Inhibition Concetration, mg/L of extract). It must be mentioned that the lower the IC 50 value, the higher the antioxidant activity of the samples. The experimental design was the Completely Random Design. Statistical analysis was performed using JMP 7 software. Proc. XXVIII th IHC – Olive Trends Symposium Eds.: J. Tous et al. Acta Hort. 924, ISHS 2011