Oleuropein Aglycone Research Articles

Relationships Between Chemical Compounds and Sensory Properties of Virgin Olive Oil in the US and Israel: Development of a Prediction Model for Defects.

Virgin olive oil (VOO) quality is defined by both chemical and sensory parameters. While the chemical parameters are objective and measured using instrument-based methods, sensory quality evaluation is based upon human panels, which can be subjective, have less repeatability, suffer from fatigue, and require long and costly training. Tasting biases could be minimized by a trained panel, but using humans as a testing instrument is inevitably prone to various psychological biases, stimulus-related factors, and carry-over effects. The objectives of this study were to evaluate instrumental methodologies that will assist the existing human panel in assessing the sensory characteristics of VOO and to develop chemistry-based predicting models for sensory properties in the oil using VOO samples originating from the US and Israel. Our results indicated that oil rancidity highly correlated with the contents of chemical components contents; 1-penten-3-one, 3-hexen-1-ol, (E)-2-pentanal, and 1-octen-3-ol are the major volatiles associated with rancidity defects (low concentrations of these compounds). Positive sensory attributes, such as fruitiness, correlated with 1- acetoxypinoresinol and hexanal, while bitterness correlated with pinoresinol, the aldehydic form of oleuropein aglycones, and the dialdehydic form of oleuropein aglycone. The random forest model suggested that luteolin, (E)-2-hexenal, 1-penten-3-one, and C18:0 are the most useful measurements in predicting the occurrence of sensory defects in the olive oil samples included. In other words, when these compounds are below or above a certain threshold, a defect, such as rancidity, is more likely to be found by the sensory panel.

Triple enzymatic cascade reaction to produce hydroxytyrosol acetate from olive leaves using integrated membrane bioreactors.

An integrated system of three membrane bioreactors (MBRs) has been developed that cascades three different enzymatic reactions. The integrated system was applied to produce hydroxytyrosol acetate from oleuropein extracted from olive leaves. Different reactor configurations for each reaction were tested and individually optimized to select the MBR to ensure high conversion and continuous production of oleuropein aglycone (OA), hydroxytyrosol (HY) and hydroxytyrosol acetate (HA). Based on this study, the most performing configuration of the integrated system was identified. In the first reaction, oleuropein was converted to OA using a biocatalytic membrane reactor (BMR) with immobilized β-glucosidase in polymeric membranes (conversion 98%). The OA was then fed to another BMR, where it was converted to HY (conversion: 70%) by an immobilized mutant of the promiscuous hydrolase/acyltransferase (PestE) (from the thermophilic archaeon Pyrobaculum calidifontis VA1). The HY produced was then acetylated using PestE immobilized on magnetic nanoparticles in a multiphase MBR (conversion: 98%) and simultaneously extracted (extraction: 98%) in ethyl acetate. The work demonstrates that continuous cascade enzymatic reactions can be engineered using artificial membranes to tailor enzyme compartmentalization, mass transport and phase contact according to reaction requirements. Besides, environmental factors proved the sustainability of the integrated membrane bioreactive system.

Phytochemical Characterization of Two New Olive Oil Genotypes Growing in Southern Tunisia.

This research can be considered as the first complete survey for the valorization of new olive genotypes cultivated in the South-East of Tunisia as well as their oils. The study aimed to characterize the phytochemical composition of virgin olive oil produced from two olive cultivars, namely Nourgou and Gousalani. The pomological characterization of fruits, the quality criteria and the phytochemical profile were quantified. Additionally, antioxidant activity was evaluated using Ferric reducing antioxidant power (FRAP) and Oxygen radical absorbance capacity (ORAC) tests to also obtain a bioactive characterization of these monovarietal olive oils. The obtained results revealed that the analyzed olive oils samples can be classified into Extra Virgin category (EVOO) according to the regulated physicochemical characteristics. Our findings showed a significant variability in the chemical parameters of the analyzed EVOO likely associated with the genetic potential, mainly for chlorophylls contents (1.37-1.64 mg/kg), in carotenoids pigments (3.97-10.86 mg/kg), in α-tocopherol (175.59-186.87 mg/kg), in sterols (1036.4-1931.4 mg/kg) in oleic acid (65.33-68.73%), in palmitic acid (C16:0) (13.32-17.48%), in linoleic acid (C18:2) (11.06-13.47%). Additionally, the HPLC-MS/MS analysis showed that the two EVOOs analyzed contained appreciable amounts of total polyphenols, ranging from 348.03 up to 516.16 mg/kg, in Nourgou and Gousalani oils, respectively. Regarding the individual phenolic compounds, the EVOO samples were mainly characterized by phenolic alcohols, phenolic acids, secoiridoids, verbascoside, flavonoids and phenolic aldehydes. The prevalent simple phenolics detected were secoiridoids with the dominance of the oleuropein aglycone in Gousalani oil. In addition, findings from in vitro antioxidant assays (FRAP and ORAC) revealed that the two studied oils possessed a powerful antiradical activity and a good reducing power capacity. In conclusion, these new EVOOs exhibited a superior quality compared to other Tunisian varieties, considering their antiradical activity and reducing power capacity.

Extra Virgin Olive Oil's Main Components' Antioxidant Activity and in Silico Effect on AKT1.

The study compared the chemical composition of various olive oils from the northern Algerian province of Bejaia. The research focused on the antioxidant activities of the oil's main constituents and their ability to inhibit the AKT1 protein, which is implicated in the development of colorectal cancer. The findings revealed that all of the examined oils fell within the extra virgin olive oil (EVOO) category and exhibited a high oleic acid content, particularly for samples from wild olives. These oils include high amount of ligstroside and oleocanthal, two important phenolic compounds. Wild olive oils stand out from cultivated ones due to their higher bitterness index. In addition, these oils have the highest concentrations of α-tocopherols and the best oxidative stability. Olive oil extracts demonstrated their antioxidant properties by neutralizing DPPH and ABTS radicals and converting ferric ions (Fe3+) to ferrous ions (Fe2+) for FRAP assay. Molecular docking was applied to assess the interaction between the main compounds identified in the analyzed olive oils and the human AKT1 protein, which is involved in the genesis of colorectal cancer. The findings revealed that lutein, oleuropein aglycone, and ligstroside aglycone had the highest binding affinity for the AKT1 protein. The present study could provide the theoretical foundation for further research on the interaction between AKT1 protein and EVOO compounds.

Molecular Dynamics Simulation Study of the Self-Assembly of Tau-Derived PHF6 and Its Inhibition by Oleuropein Aglycone from Extra Virgin Olive Oil.

Alzheimer's disease (AD) and other taupathies are neurodegenerative disorders associated with the amyloid deposition of the Tau protein in the brain. This amyloid formation may be inhibited by small molecules, which is recognized as one of the best therapeutic strategies to stop the progression of the disease. This work focuses on the small nucleating segment, hexapeptide-paired helical filament 6 (PHF6), responsible for Tau aggregation. Using computational modeling and classical molecular dynamics simulations, we show that PHF6 monomers collapse in water to form β-sheet rich structures, and the main olive oil polyphenol oleuropein aglycone (OleA) prevents peptide aggregation significantly. We gradually increase the ratio of the PHF6-OleA from 1:1 to 1:3 and find that for the 1:1 ratio, the peptide monomers are prone to form aggregated structures, while for the 1:2 ratio, the formation of the extended β-sheet structure is significantly less. For a 1:3 ratio of protein/OleA, the peptide residues are sufficiently crowded by OleA molecules through hydrogen bonding, hydrophobic interactions, and π-π stacking; hence, the peptide chains prefer to exist in a monomeric random coil conformation.

The Management of Irrigation and Potassium Fertilization to Mitigate the Effect of Light Frosts on the Phenolic and Volatile Compounds in Virgin Olive Oils.

The frequency of early frosts has increased in recent years, which are injurious to olive growing, causing losses in the yield and quality of virgin olive oil. In this research, it was studied how the management of agronomic factors mitigates frost damage in Arbequina olives, minimizing the loss of phenols and volatiles in virgin olive oil, at different fruit ripening stages. A Box-Behnken design and multivariate analysis were performed, with three levels of irrigation, potassium fertilization, and foliar copper application (15 treatments). Virgin olive oil was extracted from fresh and frozen olives. Light frost caused a significant decrease in the total phenols and secoiridoid compounds in and the antioxidant capacity of the frost-affected oils, which were perceived as more pungent and had the slight defect of "frostbitten olives". According to the Box-Behnken design, an 86% reference evapotranspiration (ET0) or higher with 100 potassium oxide units (UK2O) and a 100% ET0 or higher with 250 UK2O would be required to minimize the effect of light frost on phenols and volatiles. Partial Least Squares Regression-Discriminant Analysis (PLS-DA) differentiated the virgin olive oils according to their ripening stage and fresh and frost conditions. Moreover, PLS-DA positively correlated a 75-100% ET0 and 0 Uk2O with the dialdehydic form of the decarboxymethyl ligstroside aglycone (p-HPEA-EDA), the dialdehydic form of the decarboxymethyl oleuropein aglycone (3,4-DHPEA-EDA), the dialdehydic form of the ligstroside aglycone (p-HPEA-EDA-DLA), and with fruity, pungent, and bitter attributes. Precision agronomic management based on the needs of the crop itself would avoid unnecessary stress on olive trees and oil damage.

Phenolic enrichment of foods curated in olive oil: Kinetics and chemical evaluation

Since ancient times food has been preserved in vegetable oils for curation. Nevertheless, the transfer of bioactive compounds from these oils to curated foods has not been studied. This research has evaluated the phenolic enrichment of foods curated in olive oil. For this purpose, six foods (fish, vegetables, and cheese) were immersed in olive oil for 30 days and analyzed to determine these antioxidant phenols by LC–MS/MS. Oleuropein aglycone, hydroxytyrosol and tyrosol were the main phenols quantitatively enriched in the foods (up to 42.1, 26.2 and 53.0 mg/kg, respectively). The total phenolic content ranged from 5.8 to 12.1 mg in the evaluated foods taking as reference the recommended daily intake (150 g for fish, 200 g for vegetables, and 50 g for cheese). This research proves the phenolic enrichment of foods curated in olive oil, which can hypothetically increase their antioxidant and bioactive properties.

Antioxidant and anti-ageing effects of oleuropein aglycone in canine skeletal muscle cells

Reactive oxygen species (ROS) are normally produced in skeletal muscle. However, an imbalance in their regulatory systems can lead to their accumulation and ultimately to oxidative stress, which is one of the causes of the ageing process. Companion dogs share the same environment and lifestyle as humans, making them an excellent comparative model for the study of ageing, as well as they constitute a growing market for bioactive molecules that improve the quality of life of pets. The anti-ageing properties of oleuropein aglycone (OLE), a bioactive compound from olive leaves known for its antioxidant properties, were investigated in Myok9 canine muscle cell model. After incubation with OLE, senescence was induced in the canine cellular model by hydrogen peroxide (H2O2). Analyses were performed on cells after seven days of differentiation. The oxidative stress induced by H2O2 treatment on differentiated canine muscle cells led to a significant increase in ROS formation, which was reduced by OLE pretreatment alone or in combination with H2O2 by about 34% and 32%, respectively. Cells treated with H2O2 showed a 48% increase the area of senescent cells stained by SA-β-gal, while OLE significantly reduced the coloured area by 52%. OLE, alone or in combination with H2O2, showed a significant antioxidant activity, possibly through autophagy activation, as indicated by the expression of autophagic markers.

Dual enzyme compartmentalization in a pH-responsive membrane: A way to tune enzymatic reactions in biocatalytic membranes

In this work, the use of a pH-responsive isoporous membrane allowed the compartmentalization of two different enzymes, one on the surface and the other in the pores of the membrane. This intensified and compartmentalized enzyme-loaded membrane system allowed the two enzymatic reactions to be modulated based on a pH shift. The chosen enzymes are pectinase and β-glucosidase, enzymes commonly used in biorefinery, whose optimum pH (3 and 6.5, respectively) is in the range where membrane pore closing (pH < 4) and opening is observed. Pectinase is covalently bound to the membrane surface at pH 3 while the pores are closed and is used to control the membrane fouling due to pectin accumulation during plant material processing. β-glucosidase is immobilized in the membrane pores at pH 6.5 (open pores) and is used to catalyze the reaction of oleuropein into the phytotherapeutic oleuropein aglycone. The different localization of the two enzymes was demonstrated by AFM, immunolocalization and SEM, confocal microscopy and XPS. In the open pore configuration, a very high conversion of pectin and oleuropein is simultaneously obtained (93% and 95%, in 165 h, respectively); whereas, in the closed pore configuration, an increased and exclusive conversion (95% in 24 h) of pectin was obtained. This innovative strategy of artificial ordered compartmentalization allows tuning the enzymatic reactions based on pH, preserving labile biomolecules (e.g.β-glucosidase) from deactivation at acidic pH and cleaning the membrane avoiding aggressive solvents. This makes it possible to increase the stability of enzymes, which is an obstacle to the development of biocatalytic membrane reactors, and proposes an unconventional and efficient way to synchronize the action of complementary enzymes in a case, or to selectively enhance the action of one of them by simply shifting the pH.

Assessment of Antimicrobial and Anti-Aging Effects of Triterpenoid and Polyphenol Compounds from Olea europaea L: Extraction, Identification and In Vitro Tests

Aim: This study investigated the antimicrobial and anti-aging effects of bioactive compounds derived from Olea europaea L. leaves and flowers, widely used in traditional treatments in European and Mediterranean countries. Materials and Methods: Following solid-liquid extraction and purification steps, the control of purification processes was conducted using thin-layer chromatography (TLC). Identification of the obtained molecules was performed through high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR) analyses. For determining antimicrobial activity, representatives of Gram-positive and Gram-negative bacteria, Bacillus cereus, and Escherichia coli O15:H7, were respectively used for minimum inhibitory concentration (MIC) tests. In the assessment of Oleuropein's in vitro cytotoxicity on human dermal fibroblasts, the MTT assay was employed using HDFa cell lines, while an ELISA Test kit was utilized to determine changes in collagen type-I levels. Results: As a result of the study, molecules oleanolic acid (L1), oleuropein (L2), and ursolic acid (L3) were isolated and identified from olive leaves, whereas oleuropein aglycone (F1) molecule was isolated from olive flowers. According to the results of the Minimum Inhibitory Concentration (MIC) tests, compounds L1, L2, and L3 isolated from the leaves exhibited an inhibitory effect against Bacillus cereus within the concentration range of 5-250 µg/mL, whereas Oleuropein aglycone (F1) did not demonstrate any inhibitory activity. Furthermore, it was found that, except for the Oleuropein (L2) molecule, no other compound was effective against Escherichia coli. In the evaluation of Oleuropein's in vitro cytotoxicity on human dermal fibroblasts, a dose-dependent effect on HDFa cell viability was observed, and collagen type-I levels were significantly higher than levels obtained with vitamin C. Conclusion: Based on the obtained results, it is believed that the active molecules derived from olive plant's leaves and flowers exhibit antimicrobial effects, potentially serving as natural preservatives in the cosmetics industry. Moreover, their contribution to cell regeneration suggests potential use in wound treatments

Antioxidant activity and in silico anticholinesterase studies of major phenolic constituents of three commercial olive oils: A comparative study

This study aimed to compare the physicochemical properties, in vitro antioxidant, and total phenolic content of three commercially available olive oils in Oman and to investigate the potential neuroprotective effects of phenolic compounds through molecular docking studies. Three samples of extra virgin olive oil viz., RS (Spain), Tunisian olive oil and locally produced olive oil (Aljabal Al'akhdar) were purchased from the local market. The physicochemical parameters, total phenolic (TP) content, in vitro antioxidant activity and total antioxidant capacity were studied for comparison. In silico molecular docking studies of five phenolic compounds viz., tyrosol, hydroxy tyrosol, luteolin, oleuropein aglycone and oleocanthal on Acetylcholinesterase (AChE) enzyme was carried out to explore their possible role in Alzheimer’s disease (AD). All three samples of olive oil were found to be acidic with slight variation. The refractive indices were noted to be similar to the values reported in the literature. The oils showed excellent antioxidant activity (92.11–95.34%) and were observed to have a linear correlation with their TP content. Tunisian olive oil was observed to exhibit the best antioxidant activity, highest total antioxidant capacity and contained the maximum amount of phenolic compounds. In silico molecular docking studies showed interaction with the key residues of the active site on the target AChE protein. The inhibition of the cholinesterase activity as an additional inhibitory property makes good use of the antioxidant activity rationalizing the significance of bioactive polyphenolic compounds luteolin and oleuropein aglycone present in the olive oil, thus paving the development of natural therapeutics against AD.

Effect of Oleuropein on Anti-Obesity and Uncoupling Protein 1 Level in Brown Adipose Tissue in Mild Treadmill Walking Rats with Diet-Induced Obesity.

Oleuropein aglycone (OA), which is the absorbed form of oleuropein, is a major phenolic compound in extra virgin olive oil. We analyzed the anti-obesity effect of OA intake combined with mild treadmill walking (MTW, 4 m/min for 20 min/d, 5-6 d/wk, without electric shocks and slope) in rats under a high-fat diet (HF). Four-week-old male Sprague-Dawley rats (n=28) were equally divided into four groups: control (HF), 0.08% oleuropein-supplemented HF (HFO), HF with MTW (HF+W), and HFO with MTW (HFO+W) groups. After 28 d, the inguinal subcutaneous fat content and weight gain were significantly lower in the HFO+W group than in the control group. The HFO+W group also had significantly higher levels of urinary noradrenaline secretion, interscapular brown adipose tissue, uncoupling protein 1, brain transient receptor potential ankyrin subtype 1 (TRPA1), vanilloid subtype 1 (TRPV1), and brain-derived neurotrophic factor (BDNF) than the control group. Especially, the HFO+W group showed a synergistic effect on noradrenaline secretion. Therefore, OA combined with MTW may accelerate the enhancement of UCP1 and BDNF levels in rats with HF-induced obesity by increasing noradrenaline secretion after TRPA1 and TRPV1 activation.

Storage Effects on Bioactive Phenols in Calabrian Monovarietal Extra Virgin Olive Oils Based on the EFSA Health Claim.

The beneficial properties of extra virgin olive oil (EVOO) on lipids blood levels were recognized by the European Food Safety Authority (EFSA) with a health claim, specifically referring to EVOOs containing at least 5 mg of hydroxytyrosol and its secoiridoids derivatives per 20 g of oil. The main purpose of the work was to characterize the phenolic profile of two commercially available Calabrian monovarietal EVOOs (Nocellara del Belice, VN; Dolce di Rossano, VDR), and to study the effect of one-year storage on secoiridoids composition, by monthly controls. A new UHPLC-ESI-HRMS method was developed and validated, thus facilitating the EFSA claim application and allowing producers to valorize their products. Seven biologically active compounds were chosen: tyrosol, hydroxytyrosol, oleocanthal, oleacein, oleuropein aglycone, verbascoside, and oleuropein. LODs and LOQs were 0.001-0.02 mg g-1 and 0.002-0.08 mg g-1, respectively. The variation coefficients were ≤20% and the percentage of recovery was between 89-109%. During the 12-month storage period, the concentration of selected compounds ranged between 1258.78-1478.91 mg Kg-1 for VN, and 1408.22-2071.45 mg Kg-1 for VDR, with a decrease of 15% and 32% respectively. The method allows an accurate quantification of EVOO phenols thus being useful to certify the nutraceutical properties of olive oil.

The Protective Role of Oleuropein Aglycone against Pesticide-Induced Toxicity in a Human Keratinocytes Cell Model.

The extensive use of agricultural pesticides to improve crop quality and yield significantly increased the risk to the public of exposure to small but repeated doses of pesticides over time through various routes, including skin, by increasing the risk of disease outbreaks. Although much work was conducted to reduce the use of pesticides in agriculture, little attention was paid to prevention, which could reduce the toxicity of pesticide exposure by reducing its impact on human health. Extra virgin olive oil (EVOO), a major component of the Mediterranean diet, exerts numerous health-promoting properties, many of which are attributed to oleuropein aglycone (OleA), the deglycosylated form of oleuropein, which is the main polyphenolic component of EVOO. In this work, three pesticides with different physicochemical and biological properties, namely oxadiazon (OXA), imidacloprid (IMID), and glyphosate (GLYPHO), were compared in terms of metabolic activity, mitochondrial function and epigenetic modulation in an in vitro cellular model of human HaCaT keratinocytes to mimic the pathway of dermal exposure. The potential protective effect of OleA against pesticide-induced cellular toxicity was then evaluated in a cell pre-treatment condition. This study showed that sub-lethal doses of OXA and IMID reduced the metabolic activity and mitochondrial functionality of HaCaT cells by inducing oxidative stress and altering intracellular calcium flux and caused epigenetic modification by reducing histone acetylation H3 and H4. GLYPHO, on the other hand, showed no evidence of cellular toxicity at the doses tested. Pretreatment of cells with OleA was able to protect cells from the damaging effects of the pesticides OXA and IMID by maintaining metabolic activity and mitochondrial function at a controlled level and preventing acetylation reduction, particularly of histone H3. In conclusion, the bioactive properties of OleA reported here could be of great pharmaceutical and health interest, as they could be further studied to design new formulations for the prevention of toxicity from exposure to pesticide use.

Potential of the Oxidized Form of the Oleuropein Aglycon to Monitor the Oil Quality Evolution of Commercial Extra-Virgin Olive Oils.

The quality of commercially available extra-virgin olive oils (VOOs) of different chemical compositions was evaluated as a function of storage (12 months), simulating market storage conditions, to find reliable and early markers of the virgin olive oil (VOOs) quality status in the market. By applying a D-optimal design using the Most Descriptive Compound (MDC) algorithm, 20 virgin olive oils were selected. The initial concentrations of oleic acid, hydrophilic phenols, and α-tocopherol in the 20 VOOs ranged from 58.2 to 80.5%, 186.7 to 1003.2 mg/kg, and 170.7-300.6 mg/kg, respectively. K270, ∆K, (E, E)-2.4-decadienal and (E)-2-decenal, and the oxidative form of the oleuropein aglycon (3,4-DHPEA-EA-OX) reflected the VOO quality status well, with 3,4-DHPEA-EA-OX being the most relevant and quick index for simple monitoring of the "extra-virgin" commercial shelf-life category. Its HPLC-DAD evaluation is easy because of the different wavelength absorbances of the oxidized and non-oxidized form (3,4-DHPEA-EA), respectively, at 347 and 278 nm.

Targeted metabolic profiling of the revived ancient ‘Corbella’ olive cultivar during early maturation

‘Corbella’ is an ancient olive cultivar whose cultivation has recently been revived and hence little is known about its composition. This is the first work studying the metabolic profile of ‘Corbella’ olives during early maturation. Olives with a ripening index (RI) < 1 yielded considerably less oil content (<40%) but had more concentration of phenolic compounds (148.41–219.70 mg/kg), carotenoids (9.61–14.94 mg/kg) and squalene (521.41–624.40 mg/kg). Contrarily, the levels of α-tocopherol were higher at the RI of 1.08 and 1.96 (64.57 and 57.75 mg/kg, respectively). The most abundant phenolic compound was oleuropein aglycone (>50% of the phenolic composition), suggesting a high hydrolytic activity of β-glucosidase in the fruit. The antioxidant capacity was barely affected, while oleic/linoleic ratio reached its highest at RI of 1.96. Therefore, olives with an RI below 2 could be good candidates to produce high-quality olive oils with good level of stability.

Comparison of Drying Techniques for Extraction of Bioactive Compounds from Olive-Tree Materials.

Olive tree vegetal materials are considered a powerful source for the isolation of bioactive compounds-mainly phenols and triterpenic acids. However, the high humidity content of them reduces their preservation and extractability to a liquid solvent. Accordingly, a drying step is crucial to homogenize the material and to obtain an efficient extraction. We studied the influence of the drying process on the extraction efficiency of bioactive compounds from olive vegetal material. For this purpose, we evaluated the effects of four drying processes on the solid-liquid extraction of bioactive compounds from two by-products, olive leaves and pomace, and olive fruits harvested from two cultivars, Alfafara and Koroneiki. Infrared-assisted drying (IAD) was the most suited approach to obtain extracts enriched in oleuropein from leaves (28.5 and 22.2% dry weight in Alfafara and Koroneiki, respectively). In the case of pomace, lyophilization and microwave-assisted drying led to extracts concentrated in oleacein and oleuropein aglycone, whereas IAD and oven-drying led to extracts with enhanced contents of hydroxytyrosol glucoside and hydroxytyrosol, respectively. The drying process considerably affected the chemical composition of extracts obtained from fruits. Changes in the composition of the extracts were explained essentially by the drying process conditions using auxiliary energies, temperature, and time, which promoted chemical alterations and increased the extractability of the compounds. Therefore, the drying protocol should be selected depending on the phenolic content and initial raw material.

EVOO Polyphenols Exert Anti-Inflammatory Effects on the Microglia Cell through TREM2 Signaling Pathway.

In Alzheimer's disease (AD), microglia, brain resident immune cells, become chronically inflammatory and neurotoxic. In recent years, neuroinflammation has attracted particular interest in the scientific community. The genetic variants of molecules associated with ''microgliopathies'', including the triggering receptor expressed in myeloid cells-2 (TREM2), result in increased risk of developing AD and cognitive decline. We performed a set of in vitro assays using human neuronal (SH-SY5Y) and microglial (BV2 and C13NJ) cell models. Cells were differentially treated with extra virgin olive oil (EVOO) polyphenols, oleuropein aglycone (OleA) and hydroxytyrosol (HT) before adding LPS. We evaluated the protective effects of these EVOO products by a set of biochemical and cell biology assays, including ELISA, MTT, ROS detection, Western blotting and immunofluorescence. Our results provide an integrated understanding of the neuroprotection exerted by polyphenols in terms of: (i) reduction of pro-inflammatory cytokines release (IL-6, IL-8, IP-10 and RANTES); (ii) activation of the TREM2-dependent anti-inflammatory pathway; (iii) enhancement of protective microglial activity favoring the M2 polarization phenotype. Such findings provide new and important insights into the mechanisms by which the dietary olive polyphenols exert beneficial properties against neuroinflammation and neuronal impairment.

Maturity impact on physicochemical composition and polyphenol properties of extra virgin olive oils obtained from Manzanilla, Arbequina, and Koroneiki varieties in Iran.

This study investigated the physicochemical properties and polyphenol composition of extra virgin olive oils (EVOOs) extracted from three olive cultivars. The investigated cultivars were Arbequina, Koroneiki, and Manzanilla, grown in Olive Research Station in Rudbar county, Gilan province, Iran, at three ripening stages. Several parameters were analyzed, including peroxide and acidity values, unsaponifiable matter, oxidative stability, total aliphatic alcohols, fatty acids (FAs), sterols, and triacylglycerol composition. The results showed that as maturity increased, parameters such as oil content, acidity value, and iodine value, rise, while parameters including peroxide value, oxidative stability, aliphatic alcohols, and unsaponifiable matter decreased (p < .05). The saponification value was slightly reduced in the developing ripening process (p > .05). The MUFA/PUFA ratio and total sterol content declined during the olive ripening stages (p < .05). The triterpenes decreased in Arbequina and Koroneiki cultivars but increased in Manzanilla cultivar during the maturity stages. According to the data, oleuropein decreased while oleuropein aglycone, oxidized aldehyde, and hydroxylic form of oleuropein increased for all EVOOs during maturation. Apigenin, quercetin, ligstroside aglycone, aldehyde and hydroxylic form, ferulic acid, caffeic acid, and catechin decreased during the ripening of fruits (p < .05). The main triglycerides were triolein (OOO), palmitodiolein (POO), dioleolinolein (OOL), and palmitooleolinolein (PLO) in all EVOOs. In addition, the olive cultivar and harvesting date influence the physicochemical properties and polyphenol composition of EVOOs extracted from olive varieties grown in one region. In conclusion, the results can present helpful information to determine the optimum maturity stage for the investigated olive cultivars.

A Systematic Ex-Vivo Study of the Anti-Proliferative/Cytotoxic Bioactivity of Major Olive Secoiridoids' Double Combinations and of Total Olive Oil Phenolic Extracts on Multiple Cell-Culture Based Cancer Models Highlights Synergistic Effects.

Several individual olive oil phenols (OOPs) and their secoiridoid derivatives have been shown to exert anti-proliferative and pro-apoptotic activity in treatments of human cancer cell lines originating from several tissues. This study evaluated the synergistic anti-proliferative/cytotoxic effects of five olive secoiridoid derivatives (oleocanthal, oleacein, oleuropein aglycone, ligstroside aglycone and oleomissional) in all possible double combinations and of total phenolic extracts (TPEs) on eleven human cancer cell lines representing eight cell-culture-based cancer models. Individual OOPs were used to treat cells for 72 h in half of their EC50 values for each cell line and their synergistic, additive or antagonistic interactions were evaluated by calculating the coefficient for drug interactions (CDI) for each double combination of OOPs. Olive oil TPEs of determined OOPs' content, originating from three different harvests of autochthonous olive cultivars in Greece, were evaluated as an attempt to investigate the efficacy of OOPs to reduce cancer cell numbers as part of olive oil consumption. Most combinations of OOPs showed strong synergistic effect (CDIs < 0.9) in their efficacy, whereas TPEs strongly impaired cancer cell viability, better than most individual OOPs tested herein, including the most resistant cancer cell lines evaluated.