Comparative evaluation of physicochemical properties of four main Iranian cultivars of Olea europaea (Mary, Roghani, Fishomi and Zard)

Oleuropein, Hydroxytyrosol and Tyrosol are three major phenolic compounds present in olive with remarkable pharmacological effects. In this study, leaves and fruits of four olive cultivars including ‘Fishomi’, ‘Mary’, ‘Roghani’ and ‘Zard’ growing in the north of Iran were collected for comparative evaluation of the concentration of Oleuropein, Hydroxytyrosol and Tyrosol as well as antioxidant properties. According to the results, the highest and lowest levels of Tyrosol were detected in ‘Mary’ and ‘Zard’ leaves, respectively. There were significant differences between levels of Hydroxytyrosol in ‘Mary’ leaves compared with other examined cultivars. ‘Mary’ fruits had the highest level of Oleuropein, Hydroxytyrosol and Tyrosol, while ‘Fishomi’ fruits had the lowest level of these compounds. The total phenol content of leaf extracts was significantly higher than those detected in fruit extracts. In the leaves and fruits of the examined cultivars, the highest and the lowest Phenylalanine ammonia-lyase (PAL) activity was found in ‘Mary’ and ‘Fishomi’ cultivars, respectively. PAL activity in the leaves of all examined cultivars was significantly higher than their fruits. Meanwhile, the results showed that the antioxidant activities of the leaves in all cultivars were higher than the fruits. These results suggest that olive leaves, as well as fruits, might also be used as rich sources of natural antioxidants.