Phenolic Components and Antioxidant Activity of Wood Extracts from 10 Main Spanish Olive Cultivars

Abstract

The chemical composition and radical-scavenging activity of wood samples from 10 main Spanish olive cultivars were studied. The wood samples were collected during the pruning works from trees growing under the same agronomical and environmental conditions. The 10 ethyl acetate extracts were submitted to HPLC-DAD/ESI-MS analysis to determine the phenolic constituents. Seventeen compounds were identified (10 secoiridoids, 3 lignans, 2 phenol alcohols, 1 iridoid, and 1 flavonoid) by comparison with authentic samples. Significant quantitative and qualitative differences were found among olive cultivars. The lignan (+)-1-hydroxypinoresinol 1-O-β-d-glucopyranoside was the major compound in all olive cultivars, except in cultivars 'Farga' and 'Picual'. The multivariate analysis of all data revealed three sets of cultivars with similar compositions. Cultivars 'Gordal sevillana' and 'Picual' had the most distinct chemical profiles. With regard to the radical-scavenging activity, cultivar 'Picual', with oleuropein as the major phenolic, showed the highest activity (91.4 versus 18.6-32.7%).

RP‐HPLC‐DAD‐ESI‐QTOF‐MS based metabolic profiling of the potential Olea europaea by‐product “wood” and its comparison with leaf counterpart

“…The presence of saccharides, organic acids and iridoids was observed in the studied extracts with some qualitative differences (Tables and S1). On the one hand, the monosaccharides d ‐mannitol ( 1 ) was found in olive wood and leaves with stems, which is in agreement with previous reports on olive wood from Spanish cultivars (Pérez‐Bonilla et al, ; Salido et al, ). On the other hand, according to Liu et al () stachyose ( 2 ) and verbascose ( 3 ) were characterised for the first time in wood.…”

“…The first compounds that appeared were sugars and organic acids and last ones were secoiridoids and lignans (Table ). Furthermore, UV–vis detection data were used to primarily characterise the chemical structures, which showed equivalent to results in accordance with previous studies (Talhaoui et al, ; Klen et al, ; Mekky et al, ; Salido et al, ; Ammar et al, , ). Mass accurate determinations in the negative ionisation mode helped to identify the molecular formula of each molecular ion.…”

“…After a careful interpretation of their MS and MS/MS spectra the identified compounds were: cycloolivil glycoside ( 81 ), (−)‐olivil 4‐ O ‐ β ‐ d ‐glucopyranoside ( 82 ), cycloolivil ( 83 ), olivil ( 84 ), and (+)‐1‐hydroxypinoresinol 1‐ O ‐ β ‐ d ‐glucopyranoside ( 85 ). All aforementioned lignans were previously reported in olive wood (Pérez‐Bonilla et al, ; Salido et al, ), whereas only two of them in olive leaves (Michel et al, ). For instance, Fig.…”

“…Advances in analytical chemistry have led to the development of a wide range of analytical platforms and protocols for phytochemical screening. In the case of olive wood, previous studies have reported up to 30 different phenolic compounds (Table S1) using some spectroscopy methods such as UV, IR, 1 H–NMR, 13 C–NMR, 2D NMR (DQF‐COSY, HSQC, HMBC), and on‐line HPLC‐DAD‐DPPH/ABTS assays (Pérez‐Bonilla et al, , , , ; Zbidi et al, ; Salido et al, ). However, phenolic compounds in olive leaves have been extensively studied using a HPLC coupled to DAD and fluorometric detection, single and hybrid mass analysers such as ion trap (IT), TOF, triple quadrupole, and IT‐orbitrap (Fu et al, ; Quirantes‐Piné et al, ; Talhaoui et al, , ; Michel et al, ; Tóth et al, ) (Table S2).…”

“…In this context, wood deserves further studies, and so far little information is available about both its bioactivity and its phytochemical composition. Although recent works have identified wood constituents from Spanish olive cultivars (Altarejos et al, ; Pérez‐Bonilla et al, , ; Salido et al, ), it seems that detailed information on wood phytochemicals and other olive cultivars is still limited.…”