Simple and efficient sustainable semi-synthesis of oleacein [2-(3,4-hydroxyphenyl) ethyl (3S,4E)-4-formyl-3-(2-oxoethyl)hex-4-enoate] as potential additive for edible oils

Beneficial Effect of Olive Oil and Its Derivates: Focus on Hematological Neoplasm

Olive oil (Olea europaea) is one of the major components of the Mediterranean diet and is composed of a greater percentage of monounsaturated fatty acids, such as oleic acid; polyunsaturated fatty acids, such as linoleic acid; and minor compounds, such as phenolic compounds, and particularly hydroxytyrosol. The latter, in fact, are of greater interest since they have found widespread use in popular medicine. In recent years, it has been documented that phenolic acids and in particular hydroxytyrosol have anti-inflammatory, antioxidant, and antiproliferative action and therefore interest in their possible use in clinical practice and in particular in neoplasms, both solid and hematological, has arisen. This work aims to summarize and analyze the studies present in the literature, both in vitro and in vivo, on the possible use of minor components of olive oil in some hematological neoplasms. In recent years, in fact, interest in nutraceutical science has expanded as a possible adjuvant in the treatment of neoplastic pathologies. Although it is worth underlining that, regarding the object of our study, there are still few preclinical and clinical studies, it is, however, possible to document a role of possible interest in clinical practice.

Olea europaea L-derived secoiridoids: Beneficial health effects and potential therapeutic approaches

Over the years, health challenges have become increasingly complex and global and, at the beginning of the 21st century, chronic diseases, including cardiovascular, neurological, and chronic respiratory diseases, as well as cancer and diabetes, have been identified by World Health Organization as one of the biggest threats to human health. Recently, antimicrobial resistance has also emerged as a growing problem of public health for the management of infectious diseases. In this scenario, the exploration of natural products as supplementation or alternative therapeutic options is acquiring great importance, and, among them, the olive tree, Olea europaea L, specifically leaves, fruits, and oil, has been increasingly investigated for its health promoting properties. Traditionally, these properties have been largely attributed to the high concentration of monounsaturated fatty acids, although, in recent years, beneficial effects have also been associated to other components, particularly polyphenols. Among them, the most interesting group is represented by Olea europaea L secoiridoids, comprising oleuropein, oleocanthal, oleacein, and ligstroside, which display anti-inflammatory, antioxidant, cardioprotective, neuroprotective and anticancer activities. This review provides an overview of the multiple health beneficial effects, the molecular mechanisms, and the potential applications of secoiridoids from Olea europaea L.

Oleacein: A comprehensive review of its extraction, purification, absorption, metabolism, and health effects

Extra virgin olive oil (EVOO) consumption reduces the risk of cardiovascular disease in high-risk groups and the polyphenols in EVOO play an important health effect on it. As one of the most abundant polyphenols in EVOO, oleacein (OLEA) has many health benefits. However, there is no review article that focus comprehensively on OLEA, and most articles have limited data and information on OLEA. The purpose of this review is to summarize the results of all available studies, to present and compare the main traditional and novel techniques for the extraction and isolation and purification of OLEA, to elucidate the absorption and metabolic pathways of OLEA, and finally, to illustrate the health-promoting properties. Hopefully, this review can promote the use of OLEA in functional foods and therapeutic fields.

Dietary oleacein, a secoiridoid from extra virgin olive oil, prevents collagen-induced arthritis in mice

Olacein (OLA), one of the main secoiridoids derived from extra virgin olive oil (EVOO), has been shown to modulate oxidative and inflammatory responses in various pathological conditions; however, its potential benefit in joint disorders such as rheumatoid arthritis (RA) is unknown. Therefore, this study was designed to evaluate the preventive role of the effects of an OLA-supplemented diet in the murine model of collagen-induced arthritis (CIA), delving into the possible mechanisms and signaling pathways involved. Animals were fed an OLA-enriched preventive diet for 6 weeks prior to CIA induction and until the end of the experimental time course. On day 43 after the first immunization, mice were sacrificed: blood was collected, and paws were histologically and biochemically processed. Dietary OLA prevented collagen-induced rheumatic bone, joint and cartilage conditions. Circulating matrix metalloproteinase (MMP)-3 and proinflammatory cytokine (IL-6, IL-1β, TNF-α, IL-17) levels were significantly decreased in the joint, as well as MMP-9 and cathepsin-K (CatK) expression in secoiridoid-fed animals. In addition, dietary OLA was able to decrease COX-2, mPGES-1 and iNOS protein expressions and, also, PGE2 levels. The mechanisms possibly involved in these protective effects could be related to the activation of the Nrf-2/HO-1 axis and the inhibition of proinflammatory signaling pathways, including JAK-STAT, MAPKs and NF-κB, involved in the production of inflammatory and oxidative mediators. These results support the interest of OLA, as a nutraceutical intervention, in the management of RA.

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.

Anti-Inflammatory Effects of Olive Leaf Extract and Its Bioactive Compounds Oleacin and Oleuropein-Aglycone on Senescent Endothelial and Small Airway Epithelial Cells

Olive tree by-products have been deeply studied as an invaluable source of bioactive compounds. Several in vitro and in vivo studies showed that olive leaf extract (OLE) has anti-inflammatory and antioxidant properties. Here, we wanted to assess the valuable benefits of two less-studied OLE components-3,4-DHPEA-EDA (Oleacin, OC) and 3,4-DHPEA-EA (Oleuropein-Aglycone, OA)-directly purified from OLE using a cost-effective and environmentally sustainable method, in line with the principles of circular economy. OLE, OC and OA were then tested in human cellular models involved in acute and chronic inflammation and in the pathogenesis of viral infections, i.e., lipopolysaccharide (LPS)-treated monocyte/macrophages (THP-1) and endothelial cells (HUVECs), senescent HUVECs and Poly(I:C)-treated small airway epithelial cells (hSAECs). Results showed that OC and OA are efficient in ameliorating almost all of the pro-inflammatory readouts (IL-1β, TNF-α, IL-8, ICAM, VCAM) and reducing the release of IL-6 in all the cellular models. In hSAECs, they also modulate the expression of SOD2, NF-kB and also ACE2 and TMPRSS2, whose expression is required for SARS-CoV-2 virus entry. Overall, these data suggest the usefulness of OLE, OC and OA in controlling or preventing inflammatory responses, in particular those associated with viral respiratory infections and aging.

Solid acid-catalyzed one-step synthesis of oleacein from oleuropein

In this study, we developed a new synthetic strategy to convert secoiridoid glucosides into unique dialdehydic compounds using solid acid catalysts. Specifically, we succeeded in the direct synthesis of oleacein, a rare component of extra-virgin olive oil, from oleuropein, which is abundant in olive leaves. Whereas the conventional total synthesis of oleacein from lyxose requires more than 10 steps, these solid acid catalysts enabled the one-step synthesis of oleacein from oleuropein. A key step in this synthesis was the selective hydrolysis of methyl ester. Density functional theory calculations at the B3LYP/631+G (d) level of theory revealed the formation of a tetrahedral intermediate bonded to one H₂O molecule. These solid acid catalysts were easily recovered and reused at least five times by simple cleaning. Importantly, this synthetic procedure was not only applicable to other secoiridoid glucosides, but could also be employed for the corresponding scale-up reaction using oleuropein extracted from olive leaves as the starting material.

Hydroxytyrosol oleate: A promising neuroprotective nanocarrier delivery system of oleuropein and derivatives

Olive Phenols (OPs) are known to be potent antioxidants and possess various bioactivities and health benefits. Epidemiological studies suggested that consumption of olive oil reduces the risk of different diseases exerting a protective effect against certain malignant tumors (prostate, breast, digestive tract, endothelium, etc.). However, extremely low absorption rate of olive phenolic compounds restricts their bioactivity. In this context, solid lipid nanoparticles (SLNs) are a promising solution because they provide higher drug stability and can incorporate both lipophilic and hydrophilic drugs. Interesting experimental results have been obtained using hydroxytyrosol oleate (HtyOle) as a main component of a nanoparticle delivery system containing oleuropein (OL), oleuropein aglycone (3,4-DHPEA-EA), or hydroxytyrosol itself (Hty). In this work, hydroxytyrosol oleate (HtyOle) and hydroxytyrosol oleate (HtyOle)-based solid lipid nanoparticles were prepared and characterized. In addition, we evaluatedin vitro their antioxidant activity by DPPH assays and by ROS formation using the SH-SY5Y cell line.

The Double-Edged Sword of Oleuropein in Ovarian Cancer Cells: From Antioxidant Functions to Cytotoxic Effects

Oleuropein plays a key role as a pro-oxidant as well as an antioxidant in cancer. In this study, the activity of oleuropein, in an in vitro model of ovarian (OCCs) and breast cancer cells (BCCs) was investigated. Cell viability and cell death were analyzed. Oxidative stress was measured by CM-H2DCFDA flow cytometry assay. Mitochondrial dysfunction was evaluated based on mitochondrial reactive oxygen species (ROS) and GPX4 protein levels. Further, the effects on iron metabolism were analyzed by measuring the intracellular labile iron pool (LIP). We confirmed that high doses of oleuropein show anti-proliferative and pro-apoptotic activity on HEY and MCF-7 cells. Moreover, our results indicate that low doses of oleuropein impair cell viability without affecting the mortality of cells, and also decrease the LIP and ROS levels, keeping them unchanged in MCF-7 cells. For the first time, our data show that low doses of oleuropein reduce erastin-mediated cell death. Interestingly, oleuropein decreases the levels of intracellular ROS and LIP in OCCs treated with erastin. Noteworthily, we observed an increased amount of ROS scavenging enzyme GPX4 together with a consistent reduction in mitochondrial ROS, confirming a reduction in oxidative stress in this model.

Phenolic Compounds from Virgin Olive Oil: Approaches for Their Synthesis and Analogues

Virgin olive oil (VOO) is the main fat consumed by populations in the Mediterranean basin, and phenolic compounds, minor components of this fat, are known to be responsible for diverse health benefits when consumed in a regular diet. According to numerous investigations, these benefits are mostly related to phenols such as tyrosol and hydroxytyrosol and secoiridoid derivatives such as ligstroside, oleuropein, oleocanthal and oleacein. These compounds are present in low concentrations, and for some of them, standards are not commercially available, hampering studies on the mechanisms underlying their biological activity. In order to contribute to a better knowledge of the bioactivity of these compounds and their metabolites, they must be available with high purity and in sufficient amounts for the assays. Chemical synthesis has been considered a convenient way to obtain these compounds. This Review will focus on the synthesis of representative VOO compounds, namely, ligstroside, oleuropein, oleocanthal, oleacein and analogues.

(-)-Methyl-Oleocanthal, a New Oleocanthal Metabolite Reduces LPS-Induced Inflammatory and Oxidative Response: Molecular Signaling Pathways and Histones Epigenetic Modulation

The antioxidant and anti-inflammatory responses of (−)-methyl-oleocanthal (met-OLE), a new metabolite of the extra virgin olive oil (EVOO) phenolic oleocanthal (OLE), were explored in lipopolysaccharide (LPS)-induced murine peritoneal macrophages. Possible signaling pathways and epigenetic modulation of histones were studied. Met-OLE inhibited LPS-induced intracellular reactive oxygen species (ROS) and nitrite (NO) production and decreased the overexpression of the pro-inflammatory enzymes COX-2, mPGES-1 and iNOS in murine macrophages. In addition, met-OLE was able to significantly decrease the activation of p38, JNK, and ERK mitogen-activated protein kinases (MAPKs) and blocked canonical and non-canonical inflammasome signaling pathways. On the contrary, met-OLE upregulated haem oxigenase 1 (HO-1) and nuclear factor (erythroid-derived 2)-like 2 (Nrf-2) expression in treated cells. Finally, met-OLE pretreated spleen cells counteracted LPS induction, preventing H3K18 acetylation or H3K9 and H3K27 demethylation. Overall, these results provide novel mechanistic insights into the beneficial effects of met-OLE regarding the regulation of the immune–inflammatory response through epigenetic changes in histone markers. This revealing evidence suggests that the methylated metabolite of OLE may contribute significantly to the beneficial effects that are associated with the secoiridoid-related compound and the usual consumption of EVOO.

Novel Hydroxytyrosol-Donepezil Hybrids as Potential Antioxidant and Neuroprotective Agents

It is well-accepted that the endogenous antioxidant protection system progressively decays in elderly people, and that the oxidative stress contributes to different neurodegenerative disorders such as Alzheimer’s Diseases (AD). The lower incidence of AD in countries which feature the Mediterranean Diet was associated to the high consumption of extra virgin olive oil and its polyphenolic fraction, in particular hydroxytyrosol. The protective role of these bio-phenols against oxidative stress, suggested that we combine their antioxidant/free radical scavenging activity with donepezil, an active ingredient which has just been approved for the treatment of AD. Different synthetic strategies were tested to conjugate the two different synthons in good yields. Additionally, a nitro-hydroxytyrosol derivative was synthesized to extend the application to other neurodegeneration inflammatory models. Then, their bioactivity was measured in different chemical and biological tests on a human neuroblastoma cell line (SHSY-5Y). Remarkable results on cell viability and the regulation of the redox state of cells were obtained. All hybrids showed negligible cell death under 1 μM and are stable and non toxic. Reactive oxygen species (ROS) measurements showed that the nitro-hybrid was the more effective one at reducing the ROS amount to physiological values. Then, in light of the bio-metal hypothesis of diverse neurodegenerative disorders, we tested these new compounds on the chelation properties of redox-active metals. The nitro-hybrid was able to chelate all of the tested metal cations, suggesting that we propose it as potential lead compound for a new class of neuroprotective antioxidant agents.

Identification and Functional Characterization of Genes Encoding Phenylacetaldehyde Reductases That Catalyze the Last Step in the Biosynthesis of Hydroxytyrosol in Olive

Hydroxytyrosol derivatives are the most important phenolic components in virgin olive oil due to their well-demonstrated biological activities. In this regard, two phenyl acetaldehyde reductase genes, OePAR1.1 and OePAR1.2, involved in hydroxytyrosol synthesis, have been identified from an olive transcriptome. Both genes were synthesized and expressed in Escherichia coli, and their encoded proteins were purified. The recombinant enzymes display high substrate specificity for 2,4-dihydroxyphenylacetaldehyde (3,4-DHPAA) to form hydroxytyrosol. The reaction catalyzed by OePAR constitutes the second, and last, biochemical step in the formation of hydroxytyrosol from the amino acid L-3,4-dihydroxyphenylalanine (L-DOPA) in olive. OePAR1.1 and OePAR1.2 enzymes exhibit high thermal stability, similar pH optima (pH 6.5), and high affinity for 3,4-DHPAA (apparent Km 0.6 and 0.8 µmol min−1 mg−1, respectively). However, OePAR1.2 exhibited higher specific activity and higher expression levels in all the olive cultivars under study. The expression analyses indicate that both OePAR1.1 and OePAR1.2 genes are temporally regulated in a cultivar-dependent manner. The information provided here could be of interest for olive breeding programs searching for new olive genotypes with the capacity to produce oils with higher levels of hydroxytyrosol derivatives.

Oleacein inhibits STAT3, activates the apoptotic machinery, and exerts anti-metastatic effects in the SH-SY5Y human neuroblastoma cells

Several studies published in the last decade suggest that the beneficial role of extra-virgin olive oil (EVOO) in human health is mostly attributable to the main secoiridoid derivatives (oleuropein, oleocanthal, and oleacein). Anti-cancer properties have also been demonstrated for certain compounds present in small quantities in EVOO, including oleuropein and hydroxytyrosol, which have been extensively studied, while minor attention has been given to the most abundant secoiridoid oleacein. The aim of our research was to study the molecular mechanisms underlying the anti-proliferative and anti-metastatic capacity of oleacein in the SH-SY5Y human neuroblastoma cell line. Our results demonstrate that oleacein is able to reduce the proliferation of the SH-SY5Y cells by blocking the cell cycle in the S phase and inducing apoptotic cell death through the increase in both Bax and p53 as well as a reduction in the Bcl-2 expression and STAT3 phosphorylation. Moreover, oleacein caused reduction in the SH-SY5Y cell adhesion and migration. Overall, these findings indicate that oleacein exerts anti-cancer effects against neuroblastoma cells, suggesting a promising role as a candidate against this type of cancer.

Oleocanthal Quantification Using 1H NMR Spectroscopy and Polyphenols HPLC Analysis of Olive Oil from the Bianchera/Belica Cultivar

The cultivar Bianchera is an autochthonous variety from the eastern part of northern Italy, but it is also cultivated in the Slovenian and Croatian peninsula of Istria where it is named Belica (Slovenia) and Bjelica (Croatia). The properties of oleocanthal, a natural anti-inflammatory ibuprofen-like compound found in commercial monocultivar extra virgin olive oils, were determined by means of both quantitative ¹H NMR (qNMR) and HPLC analyses, where qNMR was identified as a rapid and reliable method for determining the oleocanthal content. The total phenolic content (TPC) was determined by means of the Folin-Ciocalteau method and the major phenols present in the olive oils were also quantified by means of HPLC analyses. All these analyses confirmed that the cultivar Bianchera was very rich in polyphenols and satisfied the health claim provided by the EU Commission Regulation on the polyphenols content of olive oils and their beneficial effects on human health.

Semi-synthesis as a tool for broadening the health applications of bioactive olive secoiridoids: a critical review

Covering: 2005 up to 2020Olive bioactive secoiridoids are recognized as natural antioxidants with multiple beneficial effects on human health. Nevertheless, the study of their biological activity has also disclosed some critical aspects associated with their application. Firstly, only a few of them can be extracted in large amounts from their natural matrix, namely olive leaves, drupes, oil and olive mill wastewater. Secondly, their application as preventive agents and drugs is limited by their low membrane permeability. Thirdly, the study of their biological fate after administration is complicated by the absence of pure analytical standards. Accordingly, efficient synthetic methods to obtain natural and non-natural bioactive phenol derivatives have been developed. Among them, semi-synthetic protocols represent efficient and economical alternatives to total synthesis, combining efficient extraction protocols with efficient catalytic conversions to achieve reasonable amounts of active molecules. The aim of this review is to summarize the semi-synthetic protocols published in the last fifteen years, covering 2005 up to 2020, which can produce natural olive bioactive phenols scarcely available by extractive procedures, and new biophenol derivatives with enhanced biological activity. Moreover, the semi-synthetic protocols to produce olive bioactive phenol derivatives as analytical standards are also discussed. A critical analysis of the advantages offered by semi-synthesis compared to classical extraction methods or total synthesis protocols is also performed.

Montmorillonite K10: An Efficient Organo-Heterogeneous Catalyst for Synthesis of Benzimidazole Derivatives

The use of toxic solvents, high energy consumption, the production of waste and the application of traditional processes that do not follow the principles of green chemistry are problems for the pharmaceutical industry. The organic synthesis of chemical structures that represent the starting point for obtaining active pharmacological compounds, such as benzimidazole derivatives, has become a focal point in chemistry. Benzimidazole derivatives have found very strong applications in medicine. Their synthesis is often based on methods that are not convenient and not very respectful of the environment. A simple montmorillonite K10 (MK10) catalyzed method for the synthesis of benzimidazole derivatives has been developed. The use of MK10 for heterogeneous catalysis provides various advantages: the reaction yields are decidedly high, the work-up procedures of the reaction are easy and suitable, there is an increase in selectivity and the possibility of recycling the catalyst without waste formation is demonstrated. The reactions were carried out in solvent-free conditions and in a short reaction time using inexpensive and environmentally friendly heterogeneous catalysis. It has been shown that the reaction process is applicable in the industrial field.

Natural Deep Eutectic Solvent as Extraction Media for the Main Phenolic Compounds from Olive Oil Processing Wastes

In this new century, sustainable development challenges chemical sciences to develop new and clean technological processes. The agri-food industry produces significant quantities of waste, raising significant economic and environmental concerns. Food waste valorization using environmentally friendly procedures is of increasing importance. This study describes the use of several Natural Deep Eutectic Solvents (NADESs) for the microwave-assisted extraction (MAE) of valuable bioactive phenolic compounds from olive oil processing wastes. The extracted samples were characterized by liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF/MS) analysis and the quantification of the phenolic compounds was performed by HPLC analysis. The obtained data were compared with those obtained using water as the solvent in the same extraction conditions. The extraction process is nontoxic, simple and selective and meets most of the criteria to be considered as a sustainable process, with the solvents arising directly from nature.

Mediterranean Diet Nutrients to Turn the Tide against Insulin Resistance and Related Diseases

Insulin resistance (IR), defined as an attenuated biological response to circulating insulin, is a fundamental defect in obesity and type 2 diabetes (T2D), and is also linked to a wide spectrum of pathological conditions, such as non-alcoholic fatty liver disease (NAFLD), cognitive impairment, endothelial dysfunction, chronic kidney disease (CKD), polycystic ovary syndrome (PCOS), and some endocrine tumors, including breast cancer. In obesity, the unbalanced production of pro- and anti-inflammatory adipocytokines can lead to the development of IR and its related metabolic complications, which are potentially reversible through weight-loss programs. The Mediterranean diet (MedDiet), characterized by high consumption of extra-virgin olive oil (EVOO), nuts, red wine, vegetables and other polyphenol-rich elements, has proved to be associated with greater improvement of IR in obese individuals, when compared to other nutritional interventions. Also, recent studies in either experimental animal models or in humans, have shown encouraging results for insulin-sensitizing nutritional supplements derived from MedDiet food sources in the modulation of pathognomonic traits of certain IR-related conditions, including polyunsaturated fatty acids from olive oil and seeds, anthocyanins from purple vegetables and fruits, resveratrol from grapes, and the EVOO-derived, oleacein. Although the pharmacological properties and clinical uses of these functional nutrients are still under investigation, the molecular mechanism(s) underlying the metabolic benefits appear to be compound-specific and, in some cases, point to a role in gene expression through an involvement of the nuclear high-mobility group A1 (HMGA1) protein.

Sustainable and Selective Extraction of Lipids and Bioactive Compounds from Microalgae

The procedures for the extraction and separation of lipids and nutraceutics from microalgae using classic solvents have been frequently used over the years. However, these production methods usually require expensive and toxic solvents. Based on our studies involving the use of eco-sustainable methodologies and alternative solvents, we selected ethanol (EtOH) and cyclopentyl methyl ether (CPME) for extracting bio-oil and lipids from algae. Different percentages of EtOH in CPME favor the production of an oil rich in saturated fatty acids (SFA), useful to biofuel production or rich in bioactive compounds. The proposed method for obtaining an extract rich in saturated or unsaturated fatty acids from dry algal biomass is disclosed as eco-friendly and allows a good extraction yield. The method is compared both in extracted oil percentage yield and in extracted fatty acids selectivity to extraction by supercritical carbon dioxide (SC-CO₂).

Eco-Friendly Extraction and Characterisation of Nutraceuticals from Olive Leaves

Olive tree (Olea europaea L.) leaf, a waste by-product of the olive oil industry, is an inexpensive and abundant source of biophenols of great interest for various industrial applications in the food supplement, cosmetic, and pharmaceutical industries. In this work, the aqueous extraction of high-added value compounds from olive leaves by using microfiltered (MF), ultrapure (U), and osmosis-treated (O) water was investigated. The extraction of target compounds, including oleuropein (Olp), hydroxytyrosol (HyTyr), tyrosol (Tyr), verbascoside (Ver), lutein (Lut), and rutin (Rut), was significantly affected by the characteristics of the water used. Indeed, according to the results of liquid chromatography tandem mass spectrometry, the extracting power of microfiltered water towards rutin resulted very poor, while a moderate extraction was observed for oleuropein, verbascoside, and lutein. On the other hand, high concentrations of hydroxytyrosol were detected in the aqueous extracts produced with microfiltered water. The extraction power of ultrapure and osmosis-treated water proved to be very similar for the bio-active compounds oleuropein, verbascoside, lutein, and rutin. The results clearly provide evidence of the possibility of devising new eco-friendly strategies based on the use of green solvents which can be applied to recover bioactive compounds from olive leaves.

Health-promoting properties of oleocanthal and oleacein: Two secoiridoids from extra-virgin olive oil

Extra virgin olive oil (EVOO) polyphenols, including the secoiridoids oleocanthal (OLC) and oleacein (OLE), are attracting attention because of their beneficial effects on health. Data on OLC and OLE bioavailability are scarce, as most research on EVOO polyphenols has concentrated on hydroxytyrosol, tyrosol, and oleuropein. Consequently, relevant goals for future research are the elucidation of OLC and OLE bioavailability and finding evidence for their beneficial effects through pre-clinical and clinical studies. The aim of this review is to shed light on OLC and OLE, focusing on their precursors in the olive fruit and the impact of agronomic and processing factors on their presence in EVOO. Also discussed are their bioavailability and absorption, and finally, their bioactivity and health-promoting properties.

Oleacein Prevents High Fat Diet-Induced Adiposity and Ameliorates Some Biochemical Parameters of Insulin Sensitivity in Mice

Oleacein is one of the most abundant polyphenolic compounds of olive oil, which has been shown to play a protective role against several metabolic abnormalities, including dyslipidemia, insulin resistance, and glucose intolerance. Herein, we investigated the effects of oleacein on certain markers of adipogenesis and insulin-resistance in vitro, in 3T3-L1 adipocytes, and in vivo in high-fat diet (HFD)-fed mice. During the differentiation process of 3T3-L1 preadipocytes into adipocytes, oleacein strongly inhibited lipid accumulation, and decreased protein levels of peroxisome proliferator-activated receptor gamma (PPARγ) and fatty acid synthase (FAS), while increasing Adiponectin levels. In vivo, treatment with oleacein of C57BL/6JOlaHsd mice fed with HFD for 5 and 13 weeks prevented the increase in adipocyte size and reduced the inflammatory infiltration of macrophages and lymphocytes in adipose tissue. These effects were accompanied by changes in the expression of adipose tissue-specific regulatory elements such as PPARγ, FAS, sterol regulatory element-binding transcription factor-1 (SREBP-1), and Adiponectin, while the expression of insulin-sensitive muscle/fat glucose transporter Glut-4 was restored in HFD-fed mice treated with oleacein. Collectively, our findings indicate that protection against HFD-induced adiposity by oleacein in mice is mediated by the modulation of regulators of adipogenesis. Protection against HFD-induced obesity is effective in improving peripheral insulin sensitivity.

Anti-tumor Activity and Epigenetic Impact of the Polyphenol Oleacein in Multiple Myeloma

Olive oil contains different biologically active polyphenols, among which oleacein, the most abundant secoiridoid, has recently emerged for its beneficial properties in various disease contexts. By using in vitro models of human multiple myeloma (MM), we here investigated the anti-tumor potential of oleacein and the underlying bio-molecular sequelae. Within a low micromolar range, oleacein reduced the viability of MM primary samples and cell lines even in the presence of bone marrow stromal cells (BMSCs), while sparing healthy peripheral blood mononuclear cells. We also demonstrated that oleacein inhibited MM cell clonogenicity, prompted cell cycle blockade and triggered apoptosis. We evaluated the epigenetic impact of oleacein on MM cells, and observed dose-dependent accumulation of both acetylated histones and α-tubulin, along with down-regulation of several class I/II histone deacetylases (HDACs) both at the mRNA and protein level, providing evidence of the HDAC inhibitory activity of this compound; conversely, no effect on global DNA methylation was found. Mechanistically, HDACs inhibition by oleacein was associated with down-regulation of Sp1, the major transactivator of HDACs promoter, via Caspase 8 activation. Of potential translational significance, oleacein synergistically enhanced the in vitro anti-MM activity of the proteasome inhibitor carfilzomib. Altogether, these results indicate that oleacein is endowed with HDAC inhibitory properties, which associate with significant anti-MM activity both as single agent or in combination with carfilzomib. These findings may pave the way to novel potential anti-MM epi-therapeutic approaches based on natural agents.

Computational de-orphanization of the olive oil biophenol oleacein: Discovery of new metabolic and epigenetic targets

The health promoting effects of extra virgin olive oil (EVOO) relate to its unique repertoire of phenolic compounds. Here, we used a chemoinformatics approach to computationally identify endogenous ligands and assign putative biomolecular targets to oleacein, one of the most abundant secoiridoids in EVOO. Using a structure-based virtual profiling software tool and reference databases containing more than 9000 binding sites protein cavities, we identified 996 putative oleacein targets involving more than 700 proteins. We subsequently identified the high-level functions of oleacein in terms of biomolecular interactions, signaling pathways, and protein-protein interaction (PPI) networks. Delineation of the oleacein target landscape revealed that the most significant modules affected by oleacein were associated with metabolic processes (e.g., glucose and lipid metabolism) and chromatin-modifying enzymatic activities (i.e., histone post-translational modifications). We experimentally confirmed that, in a low-micromolar physiological range (<20 μmol/l), oleacein was capable of inhibiting the catalytic activities of predicted metabolic and epigenetic targets including nicotinamide N-methyltransferase, ATP-citrate lyase, lysine-specific demethylase 6A, and N-methyltransferase 4. Our computational de-orphanization of oleacein provides new mechanisms through which EVOO biophenols might operate as chemical prototypes capable of modulating the biologic machinery of healthy aging.

Montmorillonite K10-Catalyzed Solvent-Free Conversion of Furfural into Cyclopentenones

A simple and eco-friendly montmorillonite K10 (MK10)-catalyzed method for the synthesis of cyclopentenone derivatives from biomass-produced furfural has been developed. The versatility of this protocol is that the reactions were performed under solvent-free conditions and in a short reaction time under heterogeneous catalysis. Montmorillonite K10 is mostly explored as a heterogeneous catalyst since it is inexpensive and environmentally friendly.

Effects of Oleacein on High-Fat Diet-Dependent Steatosis, Weight Gain, and Insulin Resistance in Mice

Many reports indicate that the protective action of nutraceuticals in the Mediterranean diet, against metabolic and cardiovascular diseases, can be attributed to the action of polyphenolic components of extra-virgin olive oil (EVOO). Here, we evaluated the protective effects of oleacein, one of the most abundant secoiridoids in EVOO, on the damages/metabolic alterations caused by high-fat diet (HFD) in male C57BL/6JolaHsd mice. After 5 weeks of treatment with 20 mg/kg of oleacein, body weight, glycemia, insulinemia, serum lipids, and histologic examination of liver tissue indicated a protective action of oleacein against abdominal fat accumulation, weight gain, and liver steatosis, with improvement of insulin-dependent glucose and lipid metabolism. Both serum parameters and hepatic histologic examination were altered in mice fed with HFD. By contrast, in the animals that received oleacein, plasma glucose, cholesterol and triglyceride serum levels, and liver histology were similar to controls fed with normocaloric diet. In addition, protein levels of FAS, SREBP-1, and phospho-ERK in liver were positively modulated by oleacein, indicating an improvement in liver insulin sensitivity. In a group of obese mice, treatment with oleacein determined a light, but still significant reduction of the increase in body weight, mainly due to lesser liver steatosis enlargement, associated with reduced levels of SREBP-1 and phospho-ERK and lower levels of total serum cholesterol; in these animals, altered plasma glucose and triglyceride serum levels were not reverted by oleacein. These results indicate that HFD-related hepatic insulin resistance may be partially prevented by oral administration of oleacein, suggesting a protective role of this nutraceutical against diet-dependent metabolic alterations. Additional studies are necessary to check whether oleacein can be used as an adjuvant to improve insulin sensitivity in humans.