Abstract
Olive leaf extracts are of special interest due to their proven therapeutic effects. However, they are still considered a by-product of the table olive and the oil industries. In order to learn possible ways of exploiting this waste for health purposes, we investigated the phytochemical profiles and antioxidant activities in the leaves of 15 Italian Olea europaea L. cultivars grown in the same pedoclimatic conditions. The phenolic profiles and amounts of their seven representative compounds were analyzed using HPLC ESI/MS-TOF. The antioxidant activities were determined using three different antioxidant assays (DPPH, ORAC, and superoxide anion scavenging assay). Wide ranges of total phenolic content (11.39–48.62 g GAE kg−1 dry weight) and antioxidant activities (DPPH values: 8.67–29.89 µmol TE mg−1 dry weight, ORAC values: 0.81–4.25 µmol TE mg−1 dry weight, superoxide anion scavenging activity values: 27.66–48.92 µmol TE mg−1 dry weight) were found in the cultivars. In particular, the cultivars Itrana, Apollo, and Maurino, showed a high amount of total phenols and antioxidant activity, and therefore represent a suitable natural source of biological compounds for use in terms of health benefits.
Highlights
In the Mediterranean area, the olive (Olea europaea L. subsp. europaea) is considered to be one of the oldest and important agricultural crops and is characterized by a large number of cultivars used for the production of olive oil and table olives [1,2,3]
Our study examined olive leaves from 15 Italian olive cultivars in order to provide basic data on their phenolic composition and antioxidant activities and to predict which one represents the best source of bioactive compounds for functional food, cosmetics, and pharmaceuticals
The phenolic compounds identified by negative ionization mode are shown in Table 1, including retention times, experimental and calculated m/z, molecular formula, errors, score, and literature references
Summary
In the Mediterranean area, the olive (Olea europaea L. subsp. europaea) is considered to be one of the oldest and important agricultural crops and is characterized by a large number of cultivars used for the production of olive oil and table olives [1,2,3]. Europaea) is considered to be one of the oldest and important agricultural crops and is characterized by a large number of cultivars used for the production of olive oil and table olives [1,2,3]. Olive leaves represent about 10% of the total biomass collected during olive oil production [6], and they are considered to be a cheap raw material which can be used as a useful source of high added-value products (phenolic compounds). Several studies have investigated the presence of a high number of phenolic compounds in olive leaves such as hydroxytyrosol, rutin, verbascoside, luteolin-7-glucoside, oleuropein, oleuropein aglycone, ligstroside [7], and other compounds such as quinic acid [8]. Oleuropein is the most abundant phenolic compound in olive cultivars [9], which is extracted as part of the phenolic fraction of olive fruits, leaves, and seeds, it has not been reported in virgin olive oils [7,10]
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