Characterisation and antioxidant activity of bioactive molecules extracted from Olea europaea leaves

The aim of our research was to investigate the total phenolic content (TPC), flavonoids (TFC), phenolic composition and antioxidant activity of olive leaf extract of five cultivars (Caiazzana, Frantoio, Leccino, Ortice and Coratina) from the Campania Region (Italy) during the phenological phase. Different microwave powers, time and three solvents (methanol, ethanol and water) in different proportions were employed. Our results show that the cultivar, the harvest-time e the solvent influence the TPC and TFC. The Caiazzana and Coratina cultivars harvested in March showed the highest TPC compared to the other cultivars, and were also particularly rich in oleuropein. Antioxidant activity was assessed by DPPH and in vitro tests on trout erythrocytes (haemolysis test) and the highest activity was found in extracts from the Caiazzana and Coratina cultivars. A higher presence of biomolecules was found in the early vegetative recovery phase characterised by phenolic compounds with high antiradical activity, particularly in the Caiazzana and Coratina cultivars. The use of these molecules extracted from waste products of the olive chain for the production of functional feeds, cosmetic products and for industrial use, may represent an important economic resource.