Total Phenolic content and antioxidant activity of leaves and drupes in major Greek olive varieties

Abstract

The total phenolic content and the antioxidant activity were determined for leaves and drupes of the major Greek olive varieties 'Koroneiki', 'Lianolia Kerkyras', 'Mastoidis', 'Adramytini', 'Megaritiki', 'Gaidourelia', 'Kalamata', 'Konservolia', 'Chalkidiki' and the Spanish variety 'Arbequina'. Leaves were collected in April, September and December, and drupes were collected green and black, for two consecutive years and investigated for their total phenolic content and antioxidant activity, using the Folin-Ciocalteu and the DPPH assays, respectively. The data obtained from this work showed that the total phenolic content and the antioxidant activity of all varieties per tissue have varied significantly since different varieties exhibited statistically significant different values. Furthermore, within each variety, tissue was an important parameter for both the total phenolic content and the antioxidant activity, as different tissues exhibited statistically significant differences for both measurements. For the varieties studied, and for both years, new season leaves on April showed the highest total phenolic content followed by green and black drupes with a few exceptions. Also new season leaves on April showed the highest total phenolic content than the leaves of September and December of the same year with a few exceptions also. A positive correlation (r=0.793**) between the antioxidant activity and the total phenolic content was found.