Antioxidant Capacity of Free Volatile Compounds from Olea europaea L. cv. Oblica Leaves Depending on the Vegetation Stage.

Renata Jurišić Grubešić,Elma Vuko,Ivica Ljubenkov,Marija Nazlić,Tina Miletić,Valerija Dunkić,Nenad Vuletić

doi:10.3390/antiox10111832

Abstract

Previous research on specialized metabolites of olive leaves has focused on the phenolic components and their biological role. The research in this article focuses on the metabolites that form free volatile compounds (FVCs). The composition of FVCs is divided into compounds isolated in the oil phase (essential oils; EO) and in the aqueous phase (hydrosols; Hy) from leaves of Olea europaea L. cultivar Oblica. Plant material was collected from the same olive tree over a six-month period, from December to May, and analyzed by gas chromatography–mass spectrometry (GC–MS). The compounds β-caryophyllene, α-humulene, allo-aromadendrene, docosane, hexadecanoic acid and oleic acid were identified in all EO study periods. In the Hy in all studied periods, the major compounds are α-pinene, β-ionone, myristicin, docosane, 1-hexanol, oleic acid and (E)-β-damascenone. The differences in the qualitative composition of FVC are directly related to the phenological development of the leaves. Antioxidant capacity of the EOs and hydrosols was measured with two methods, ORAC and DPPH. Hydrosol extracts showed higher capacity than the EOs in all methods.

Highlights

Olea europaea L. (Oleaceae)—the olive—is cultivated in various parts of the world, with the Mediterranean region still being the largest growing region due to its climate of warm, dry summers and cold, rainy winters [1]
Pretreatment is important for the isolation of the target substances, olive leaves are prepared under different conditions for extraction [9]
The results of this study show that oleic acid and docosane are components identified in the hydrophilic and lipophilic phases, i.e., essential oil and hydrosol, extracted from the leaves of Olea europaea cv

Summary

Introduction

Olea europaea L. (Oleaceae)—the olive—is cultivated in various parts of the world, with the Mediterranean region still being the largest growing region due to its climate of warm, dry summers and cold, rainy winters [1]. (Oleaceae)—the olive—is cultivated in various parts of the world, with the Mediterranean region still being the largest growing region due to its climate of warm, dry summers and cold, rainy winters [1] This plant is so popular because the Mediterranean diet is considered one of the healthiest diets in the world and olive oil is one of the most important dietaries of this diet [2]. Europaea is a subspecies considered drought resistant because it grows in an areas where it is frequently exposed to stress (e.g., lack of water), which is characteristic of the Mediterranean region [3]. It is divided into a wild form O. europaea subsp. The area under olive cultivation in Croatia is very large and the most important variety is “Oblica”, which is the subject of the present study [5,6]

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Results

Conclusion