Microbial Application to Improve Olive Mill Wastewater Phenolic Extracts

Olive mill wastewater (OMW) contains valuable and interesting bioactive compounds, among which is hydroxytyrosol, which is characterized by a remarkable antioxidant activity. Due to the health claims related to olive polyphenols, the aim of this study was to obtain an extract from OMW with an increased level of hydroxytyrosol by means of microbial enzymatic activity. For this purpose, four commercial adsorbent resins were selected and tested. The beta-glucosidase and esterase activity of strains of Wickerhamomyces anomalus, Lactiplantibacillus plantarum, and Saccharomyces cerevisiae were also investigated and compared to those of a commercial enzyme and an Aspergillus niger strain. The W. anomalus strain showed the best enzymatic performances. The SP207 resin showed the best efficiency in selective recovery of hydroxytyrosol, tyrosol, oleuropein, and total phenols. The bioconversion test of the OMW extract was assessed by using both culture broths and pellets of the tested strains. The results demonstrated that the pellets of W. anomalus and L. plantarum were the most effective in hydroxytyrosol increasing in phenolic extract. The interesting results suggest the possibility to study new formulations of OMW phenolic extracts with multifunctional microorganisms.     

UV-Vis光谱差减法测定油橄榄叶中橄榄苦苷含量初探

建立了紫外-可见(UV-Vis)分光光谱测定油橄榄叶中橄榄苦苷含量的方法.以芦丁和橄榄苦苷为对照品,分别采用NaNO2-Al(NO3)3-NaOH络合体系和AlCl3络合体系进行显色.以NaNO2-Al(NO3)3-NaOH体系显色后于510 nm处可测得油橄榄叶中总黄酮和橄榄苦苷的吸光度之和;而以AlCl3体系显色后...     

橄榄苦甙的NMR数据解析

对橄榄苦甙进行了¹H和¹³C MNR检测, 通过DEPT和¹H-¹H COSY、HMQC、HMBC、NO ESY等2D NMR对其¹H和¹³C NMR数据进行了全归属和较详细的解析, 并指出其NMR数据特征.     

Synthesis of deuterium-labelled substrates for the study of oleuropein biosynthesis in Olea europaea callus cultures

We propose the cell culture approach to investigate oleuropein (1) biogenesis in Olea europaea L. We suggest employing olive callus cultures to identify the iridoidic precursor of oleuropein. In fact, we confirmed that callus cells from olive shoot explants are able to produce key secoiridoid as 1. To enable this approach, we synthesised and characterised deuterium-labelled iridoidic precursors belonging both to the loganin and the 8-epiloganin series. These iridoids are [7,8-²H₂]-7-deoxy-8-epi-loganin (2^D), [8,10-²H₂]-8-epi-loganin (4^D) and [7,8-²H₂]-7-deoxy-loganin (3^D).     

Olive Pomace Phenolic Compounds Stability and Safety Evaluation: From Raw Material to Future Ophthalmic Applications

Nowadays, increasing interest in olive pomace (OP) valorization aims to improve olive’s industry sustainability. Interestingly, several studies propose a high-value application for OP extracts containing its main phenolic compounds, hydroxytyrosol and oleuropein, as therapy for ocular surface diseases. In this work, the stability and accessibility of OP total phenolic and flavonoid content, main representative compounds, and antioxidant activity were assessed under different pretreatment conditions. Among them, lyophilization and supercritical CO₂ extraction were found to increase significantly most responses measured in the produced extracts. Two selected extracts (CONV and OPT3) were obtained by different techniques (conventional and pressurized liquid extraction); Their aqueous solutions were characterized by HPLC-DAD-MS/MS. Additionally, their safety and stability were evaluated according to EMA requirements towards their approval as ophthalmic products: their genotoxic effect on ocular surface cells and their 6-months storage stability at 4 different temperature/moisture conditions (CPMP/ICH/2736/99), together with pure hydroxytyrosol and oleuropein solutions. The concentration of hydroxytyrosol and oleuropein in pure or extract solutions was tracked, and possible degradation products were putatively identified by HPLC-DAD-MS/MS. Hydroxytyrosol and oleuropein had different stability as standard or extract solutions, with oleuropein also showing different degradation profile. All compounds/extracts were safe for ophthalmic use at the concentrations tested.     

Phenolic composition,antioxidant and antinociceptive activities of Syringa vulgaris L. bark and leaf extracts

Metabolite profile, antioxidant and antinociceptive activities of Syringa vulgaris bark and leaf methanolic extracts were investigated. By means of HPLC-DAD-ESI-TOF and HPLC-DAD-ESI-MS/MS, a total of 33 phenolics were identified, including 15 secoiridoids, 6 phenylpropanoids, 3 flavonoids, 3 lignans and 6 low molecular weight phenols. Validated quantitative analysis show that syringin (2.52%) and rutin (1.13%) are the main phenolic compounds in bark and leaf, respectively. Notable radical scavenging and antinociceptive activities of the bark and leaf extracts were confirmed by in vitro DPPH^● and ABTS^●+ assays and by in vivo hot-plate method in mice, respectively. Our results could lay the scientific basic of future clinical perspectives of lilac bark and leaf.     

Oleuropein as a Potent Compound against Neurological Complications Linked with COVID-19: A Computational Biology Approach

The association of COVID-19 with neurological complications is a well-known fact, and researchers are endeavoring to investigate the mechanistic perspectives behind it. SARS-CoV-2 can bind to Toll-like receptor 4 (TLR-4) that would eventually lead to α-synuclein aggregation in neurons and stimulation of neurodegeneration pathways. Olive leaves have been reported as a promising phytotherapy or co-therapy against COVID-19, and oleuropein is one of the major active components of olive leaves. In the current study, oleuropein was investigated against SARS-CoV-2 target (main protease 3CL^pro), TLR-4 and Prolyl Oligopeptidases (POP), to explore oleuropein potency against the neurological complications associated with COVID-19. Docking experiments, docking validation, interaction analysis, and molecular dynamic simulation analysis were performed to provide insight into the binding pattern of oleuropein with the three target proteins. Interaction analysis revealed strong bonding between oleuropein and the active site amino acid residues of the target proteins. Results were further compared with positive control lopinavir (3CL^pro), resatorvid (TLR-4), and berberine (POP). Moreover, molecular dynamic simulation was performed using YASARA structure tool, and AMBER14 force field was applied to examine an 100 ns trajectory run. For each target protein-oleuropein complex, RMSD, RoG, and total potential energy were estimated, and 400 snapshots were obtained after each 250 ps. Docking analyses showed binding energy as −7.8, −8.3, and −8.5 kcal/mol for oleuropein-3CL^pro, oleuropein-TLR4, and oleuropein-POP interactions, respectively. Importantly, target protein-oleuropein complexes were stable during the 100 ns simulation run. However, an experimental in vitro study of the binding of oleuropein to the purified targets would be necessary to confirm the present study outcomes.     

Production of glucose and bioactive aglycone by chemical and enzymatic hydrolysis of purified oleuropein fromOlea Europea

Pure-grade oleuropein, a bitter, hypotensive, phenolic glucoside, was obtained from organic extracts of olive plant leaves by two Chromatographic steps. The purified compound was characterized by spectroscopic NMR and FAB-MS methods. The glucoside underwent chemical and enzymatic hydrolysis. Aglycone was characterized by spectroscopic methods (¹H-NMR and FAB-MS). Glucose was measured by enzymatic methods. The enzymatic hydrolysis of oleuropein was carried out by a soluble β-glucosidase. The reaction was characterized in terms of kinetic parameters, optimal pH value, activation energy, inhibition constant by glucose, and thermal stability. Preliminary experiments were also performed in a continuousflow ultrafiltration membrane reactor. The cut-off of the membrane was lower than the molecular-weight of the enzyme, thus determining β-glucosidase confinement within the reactor. Under these conditions, β-glucosidase had a good long-term stability. This is an encouraging result in view of possible industrial applications.     

Study of the phenolic composition of spanish and italian monocultivar extra virgin olive oils: Distribution of lignans, secoiridoidic, simple phenols and flavonoids

The aim of the present study was to compare the phenolic content in selected monocultivar extra virgin olive oils. Analyses were carried out by HPLC/DAD/MS on Picual, Picuda, Arbequina and Hojiblanca oils from Spain and Seggianese and Taggiasca oils from Italy. Oils from cultivar Picual showed similar characteristics to those of Seggianese oils, with total amounts of secoiridoids of 498.7 and 619.2 mg/L, respectively. The phenolic composition of Arbequina oils is close to that of the Taggiasca variety with lignans among the main compounds. The determination of free and linked OH-Tyr, by way of an acid hydrolysis, represents a rapid and suitable method, especially when standards are not available, to determine antioxidant potentialities in terms of MPC, particularly for fresh extra virgin olive oils rich in secoiridoidic derivatives.     

The biotransformation of oleuropein in rats

A highly sensitive and specific LC‐MS/MS method was developed to investigate the in vivo bio‐transformation of oleuropein in rat. Rat feces and urine samples collected after oral administration were determined by liquid chromatography coupled to tandem mass spectrometry with electrospray ionization in the negative‐ion mode. The assay procedure involves a simple liquid–liquid extraction of parent oleuropein and the metabolite from rat feces and urine with ethyl acetate. Chromatographic separation was operated with 0.1% formic acid aqueous and methanol in gradient program at a flow rate of 0.50 mL/min on an RP‐C₁₈ column with a total run time of 31 min. This method was successfully applied to simultaneous determination of oleuropein and its metabolites in rat feces and urine. De‐glucosylation, hydrolysis, oxygenation and methylation were found to comprise the major metabolic pathway of oleuropein in rat gastrointestinal tract and three metabolites were absorbed into the blood circulatory system within 24 h after oral administration. Copyright © 2013 John Wiley & Sons, Ltd.