Antioxidant activity of olive leaves extracts from Greek cultivars
Olive leave extracts from four Greek cultivars (koroneiki, megaritiki, kalamon and amfisis) were obtained using different solvents (methanol/water, water, petrol ether, and dichloromethane). The phenol composition was determined for the three cultivars by MS. The following compounds were identified. Secologanoside, demethyloleuropein, oleuropein diglucoside, luteolin-7-O-glucoside, rutin, oleuropein, oleuroside, quercetrin, ligstroside and verbascoside. The compound oleuropein was found to be in higher concentration in all cultivars.
Extracts were tested for their possible antioxidant activities as interaction with the stable free radical DPPH. In all cases methanol/water and water extracts presented significant antioxidant activity. They have also been tested for their inhibitory activity against lipoxygenase. Again methanol/water and water extracts showed significant inhibitory activity, although there are some differences among the extracts of the different types of olives. A correlation between radical scavenging capacities of extracts with total phenol compounds content was observed. Free radicals play an important role in inflammatory process. Consequently, leave extracts with antioxidant/scavenging properties could be expected to offer protection in rheumatoid arthritis and inflammation.