Study of the effects of variety and season of collection on the amounts of bioactive compounds in Algerian olive leaves

Abstract

This study explored the bioactive contents (including chlorophyll, carotenoid, phenolic and flavonoid compounds) of olive leaves (Olea europaea L.) from three Algerian cultivars (Aberkane, Aharoun, and Akerma) across four distinct seasonal periods (autumn, winter, spring, and summer). The investigation involved performing antioxidant potential tests. The findings indicated that all cultivars are rich in bioactive compounds and the Aberkane olive leaves exhibited the highest levels of chlorophyll a (2518.79 ± 19.32 µg/g), chlorophyll b (816.22 µg/g), carotenoid (120.22 ± 6.72 µg/g) phenolic (596.97 ± 29.07 mg GAE/g DE) and flavonoid (374.05 ± 12.54 mg EQ/g DE) compounds. Aberkane olive leaves presented also the best results of DPPH scavenger activity (IC50: 38.40 ± 1.75 µg/ml) and ferric reducing power (A0.5: 22.34 ± 1.98 µg/ml). In general, leaves collected during summer demonstrated the highest contents of bioactive compounds and the best antioxidant activities, compared to other seasons. Consequently, it can be deduced that both the cultivar type and the season of collection exert significant influences on the bioactive content and antioxidant potential of olive leaves.