Variations in phenolic compounds and antiradical scavenging activity of Olea europaea leaves and fruits extracts collected in two different seasons

Abstract

Olea europaea L. leaves and fruits were sampled in Mahdia region (center of Tunisia) according to the biological cycle of olive in order to analyze their phenolic compounds and to ascertain their antiradical scavenging activity. The harvesting time effect on HPLC analysis of olive leaves and fruits was significant. The results indicated that there is a decrease in total polyphenols, total o-diphenols and total flavonoids, when the leaves are still growing and in the ripe fruits, whereas they increase when the leaves have completed their growth and in the unripe fruits. Total tannins and carotenoids contents of leaves presented non similar variation to total polyphenols, o-diphenols and flavonoids during the vegetative cycle of olive. The comparison of the antioxidant capacity allowed us to conclude that that the leaves collected at two different stages of the vegetative cycle of olive showed higher value of antioxidant activity, based on ABTS radical-scavenging activity than the unripe and ripe fruits from the two studied varieties.