Identification of Predominant Phytochemical Compounds and Cytotoxic Activity of Wild Olive Leaves (Olea europaea L. ssp. sylvestris) Harvested in South Portugal

Abstract

This study has been aimed at providing a qualitative and quantitative evaluation of selected phytochemicals such as phenolic acids, flavonoids, oleuropein, fatty acids profile, and volatile oil compounds, present in wild olive leaves harvested in Portugal, as well as at determining their antioxidant and cytotoxic potential against human melanoma HTB-140 and WM793, prostate cancer DU-145 and PC-3, hepatocellular carcinoma Hep G2 cell lines, as well as normal human skin fibroblasts BJ and prostate epithelial cells PNT2. Gallic, protocatechuic, p-hydroxybenzoic, vanillic acids, apigenin 7-O-glucoside, luteolin 7-O-glucoside, and rutin were identified in olive leaves. The amount of oleuropein was equal to 22.64 g/kg dry weight. (E)-Anethole (32.35%), fenchone (11.89%), and (Z)-3-nonen-1-ol (8%) were found to be the main constituents of the oil volatile fraction, whereas palmitic, oleic, and alpha-linolenic acid were determined to be dominating fatty acids. Olive leaves methanol extract was observed to exerted a significant, selective cytotoxic effect on DU-145 and PC-3 cell lines. Except the essential oil composition, evaluated wild olive leaves, with regard to their quantitative and qualitative composition, do not substantially differ from the leaves of other cultivars grown for industrial purposes and they reveal considerable antioxidant and cytotoxic properties. Thus, the wild species may prove to be suitable for use in traditional medicine as cancer chemoprevention.

Phytochemical and antioxidant analysis of medicinal and food plants towards bioactive food and pharmaceutical resources

“…Melnyk et al 46 identified rutin as the highest content of phenolics in the rue methanolic extract, consistent with the present work. Several studies 48 , 49 have reported oleuropein and its derivatives as the dominant phenolics in the olive leaf, according with our results. As shown in data (Table 2 and Fig.…”

“…In some cases, phenylethanoids, which are phenethyl alcohol-structured phenolic antioxidants, were abundantly found in olive leaves, including oleuropein and its derivatives, followed by tyrosol and verbascoside. These molecules may conduct to its high antioxidant properties 11 , 49 . Tyrosol existed in highest concentration in rosemary (4.56 mg g −1 ), but in small quantity in olive leaf (0.75 mg g −1 ) and rue (0.19 mg g −1 ).…”

Evaluation of Phytochemical and Antioxidant Properties of 15 Italian Olea europaea L. Cultivar Leaves

“…The other two molecules, luteolin (from traces to a maximum of 3 g/kg −1 DW) and verbascoside, were detected at low levels in all the cultivars examined, in accordance with the literature [4,26]. Verbascoside is a hydroxycinnamic derivative typical of olive fruit and it has been found in small amounts in olive leaves, as reported by Makowska-Wazs et al [40] for wild olive trees and by Pereira et al [41] for the Portuguese olive cultivar Cobrançosa.…”

Influence of different light conditions and time of sprouting on harmful and beneficial aspects of rutabaga sprouts in comparison to their roots and seeds

“…Flavonoid and phenolic acid analysis was performed according to Makowska‐Wąs et al ., using a Dionex HPLC system with a PDA 100 UV–visible detector Hypersil Gold (C‐18) column (5 µm, 250 × 4.6 mm, Thermo EC) mobile phase of 1% formic acid in water (A) and acetonitrile (B) in a gradient mode 5–60% B over 60 min, at a flow rate of 1 mL min −1 . Identification of the compounds was conducted by comparing their retention times and UV spectrum with those of the standards (phenolic acids: caffeic, chlorogenic, gentisic, sinapic and ferulic; and flavonoids: isoquercitrin, robinin, morin, myricetin, apigenin, kaempferol and quercetin were used; 10 mg of each standard was dissolved in 10 mL HPLC‐purity methanol to obtain 1 mg mL −1 stock solution).…”