Olive oils rich in natural catecholic phenols decrease isoprostane excretion in humans

Cardiovascular and Metabolic Benefits of Extra Virgin Olive Oil Phenolic Compounds: Mechanistic Insights from In Vivo Studies

Extra virgin olive oil (EVOO) represents a significant source of monounsaturated fatty acids (MUFA) and vitamin E, but it is also considered a functional food, due to the content of peculiar bioactive molecules, such as phenolic compounds, being able to modulate various processes related to aging and the most common metabolic and degenerative diseases. A lot of experimental research has focused on some of these components, but in most cases, the studies were performed in vitro testing compounds at non-physiological concentrations and achieving results that cannot easily be translated in vivo. Recent clinical studies demonstrated that in vivo these compounds are able to regulate physiological functions and prevent several pathological events including metabolic and cardiovascular diseases (CVDs), which represent the main causes of death worldwide. This review aims to sum up the major evidence on the beneficial effects of EVOO phenolic compounds in vivo on these pathologies, describing and evaluating the efficacy in relation to the mechanisms of diseases of the whole phenolic fraction and some of its specific components.

Efficacy of Hydroxytyrosol-Rich Food Supplements on Reducing Lipid Oxidation in Humans

In the present study we report the efficacy of two food supplements derived from olives in reducing lipid oxidation. To this end, 12 healthy volunteers received a single dose (25 mL) of olive phenolics, mainly hydroxytyrosol (HT), provided as a liquid dietary supplement (30.6 or 61.5 mg HT), followed by an investigation of two reliable markers of oxidative stress. Blood and urine samples were collected at baseline and at 0.5, 1, 1.5, 2, 4, and 12 h post-intake. Plasma-oxidized low-density lipoprotein (oxLDL) cholesterol levels were measured with ELISA using a monoclonal antibody, while F2-isoprostanes (F2-IsoPs) were quantified in urine with UHPLC-DAD-MS/MS. Despite the great variability observed between individuals, a tendency to reduce lipoxidation reactions was observed in the blood in response to a single intake of the food supplements. In addition, the subgroup of individuals with the highest baseline oxLDL level showed a significant (p < 0.05) decrease in F2-IsoPs at 0.5 and 12 h post-intervention. These promising results suggest that HT supplementation could be a useful aid in preventing lipoxidation. Additionally, people with a redox imbalance could benefit even more from supplementing with bioavailable HT.

Ameliorative Effects of some Natural Antioxidants against Blood and Cardiovascular Toxicity of Oral Subchronic Exposure to Silicon Dioxide, Aluminum Oxide, or Zinc Oxide Nanoparticles in Wistar Rats

The present study determines the possible protective role of fig fruit extract with olive oil and date palm fruit extract (FOD) in decreasing the oral subchronic blood and cardiovascular toxicity of SiO₂NPs, Al₂O₃NPs, or ZnONPs. The present study used 80 male Wistar rats (8 groups, n = 10) distributed according to the treatment. The FOD treatments were used at their recommended antioxidant doses. All nanoparticles (NPs) were given orally and daily at doses of 100 mg/kg for 75 days. The oral administration of different NPs alone led to dramatic, oxidative stress, inflammatory markers, blood coagulation, endothelial dysfunction markers, myocardial enzymes, hematological parameters, lipid profile, and histopathological features compared with the control group. The FOD-NP-treated groups recorded significantly ameliorated blood and cardiovascular toxicity hazards compared to the groups administered with the NPs alone. In conclusion, the administration of FOD provides considerable chemopreventive and ameliorative effects against NP toxicity.

Oleuropein Improves Cognitive Dysfunction and Neuroinflammation in Diabetic Rats through the PI3K/Akt/mTOR Pathway

Objective

To explore the effect and mechanism of oleuropein on cognitive dysfunction and neuroinflammation in diabetic rats.

Method

A diabetic rat model was constructed using streptozotocin, and the diabetic rats were divided into 3 groups with different treatment for 4 weeks, named STZ group (gavaged with normal saline), STZ+LOE group (40 mg/kg oleuropein, and STZ+SITA group (30 mg/kg sitagliptin). The fasting blood glucose (FBG), fasting serum insulin levels, and HOMA-IR index were measured in rats. After the last treatment, the Morris water maze experiment was carried out, and the rats were first subjected to training experiments for 4 consecutive days; the escape latency, number of crossing platform quadrant intersections, time spent in the target quadrant, and swimming speed were recorded. Additionally, the malondialdehyde (MDA), myeloperoxidase (MPO) content, superoxide dismutase (SOD) activity, interleukin- (IL-) 1β, tumor necrosis factor (TNF-α), and phosphatidylinositol 3-kinases (PI3K)/threonine-protein kinase (Akt)/mTOR expression levels in rat hippocampus tissues were detected.

Results

Oleuropein reduced insulin resistance, spatial learning, and memory ability in diabetic rats. It also could improve oxidative stress and inflammatory response and activate the PI3K/Akt/mTOR signaling pathway in hippocampus tissues.

Conclusion

Oleuropein ameliorates cognitive dysfunction and neuroinflammation in diabetic rats by regulating the PI3K/Akt/mTOR signaling pathway.

Polyphenols and Their Metabolites in Renal Diseases: An Overview

Kidney diseases constitute a worldwide public health problem, contributing to morbidity and mortality. The present study aimed to provide an overview of the published data regarding the potential beneficial effects of polyphenols on major kidney diseases, namely acute kidney injury, chronic kidney disease, diabetic nephropathy, renal cancer, and drug-induced nephrotoxicity. This study consists of a bibliographical review including in vitro and in vivo studies dealing with the effects of individual compounds. An analysis of the polyphenol metabolome in human urine was also conducted to estimate those compounds that are most likely to be responsible for the kidney protective effects of polyphenols. The biological effects of polyphenols can be highly attributed to the modulation of specific signaling cascades including those involved in oxidative stress responses, anti-inflammation processes, and apoptosis. There is increasing evidence that polyphenols afford great potential in renal disease protection. However, this evidence (especially when in vitro studies are involved) should be considered with caution before its clinical translation, particularly due to the unfavorable pharmacokinetics and extensive metabolization that polyphenols undergo in the human body. Future research should consider polyphenols and their metabolites that indeed reach kidney tissues.

The olive constituent oleuropein exerts nephritic protective effects on diabetic nephropathy in db/db mice

BACKGROUND

Oleuropein, the most prevalent polyphenol in olives, exerts many positive impacts on human health, including counteracting cancer. However, the effect of oleuropein on diabetic nephropathy (DN) progression remains elusive.

METHODS

A total of three groups of mice were used in our study. Two groups of db/db mice fed with or without oleuropein. A group of wide-type mice fed with normal diet was used as normal control. After ten weeks of treatment, the body weight, biochemical parameters, oxidative stress markers, inflammatory cytokines levels, and kidney injury status were measured.

RESULTS

Our results demonstrated that oral administration of oleuropein reduced body weight, alleviated kidney injury, and decreased oxidative stress and inflammatory response in db/db mice. The oleuropein inhibited cell apoptosis via regulation of MAPK signalling pathways and its downstream targets Bax, caspase-3, and Bcl-2 expression.

CONCLUSION

Oleuropein may server as a favourable additional agent for the treatment of patients with DN.

Cellular Antioxidant Effects and Bioavailability of Food Supplements Rich in Hydroxytyrosol

The present study evaluates the effect of olive (Olea europaea L.) vegetation water on human cells regarding its antioxidant properties and radical scavenger bioactivities. To this aim, two food supplements containing concentrated olive water in combination with 6% lemon juice or 70% grape juice, respectively, were assessed in different oxidation assays. From the investigated polyphenols, hydroxytyrosol, present in olives and in a lesser extent in grapes, was found to be the most abundant in both formulations, followed by tyrosol and oleuropein for the olive-derived concentrate with lemon juice, and by proanthocyanidins and tyrosol for the olive concentrate with grape juice. Cellular studies suggest that both formulations are effective antioxidants. In particular, the combination of olive and grape extracts showed a remarkable superoxides-, hydroxyl radicals-, and hydrogen peroxides-scavenging activity, while the formulation containing 94% olive concentrate wasmore potent in protecting the cells against lipoxidation. Both products showed a significant and similar effect in preventing advanced glycation end products’ (AGEs) formation. In addition, preliminary data indicate that hydroxytyrosol is absorbed into the human body when administered via these hydrophilic matrices, as confirmed by the urinary excretion of free hydroxytyrosol. Since the availability of phytochemicals largely depends on the vehicle in which they are solved, these findings are of relevance and contribute to supporting the healthful effects here assessed in a cellular environment.

Extra virgin olive oil: More than a healthy fat

The beneficial effects of a Mediterranean diet on human health and, in particular, on lowering risk of cardiovascular disease, has been mainly attributed to its high content to extra virgin olive oil (EVOO). While its main fatty acid, oleic acid, is considered important to these effects, EVOO has other biological properties that depend on, or are potentiated by other minor components of this oil. Initially, the mechanisms considered as possible causes of this cardioprotective effect of EVOO were based on the incidence on the so-called traditional risk factors (especially lipids and blood pressure). However, the high relative reduction in the prevalence of cardiovascular morbidity and mortality were not proportional to the limited findings about regulation of those traditional risk factors. In addition to several studies confirming the above effects, current research on beneficial effect of EVOO, and in particular in conjunction with Mediterranean style diets, is being focused on defining its effects on newer cardiovascular risk factors, such as inflammation, oxidative stress, coagulation, platelet aggregation, fibrinolysis, endothelial function or lipids or on the modulation of the conditions which predispose people to cardiovascular events, such as obesity, metabolic syndrome or type 2 diabetes mellitus. In the current review, we will mainly focus on reviewing the current evidence about the effects that EVOO exerts on alternative factors, including postprandial lipemia or coagulation, among others, discussing the underlying mechanism by which it exerts its effect, as well as providing a short review on future directions.

Oleuropein protects against lipopolysaccharide-induced sepsis and alleviates inflammatory responses in mice

Sepsis results from a major systemic inflammatory response and can induce disorders in multiple organs. The present study evaluated the potential protective effects of oleuropein (OLE) against hyperinflammatory responses during lipopolysaccharide (LPS)-induced sepsis in mice. Sixty male Balb/c mice were randomly categorized into five groups of 12 animals each: control, intraperitoneally injected with OLE (50 mg/kg), injected with LPS (10 mg/kg, intraperitoneal), and two groups administered OLE (25 and 50 mg/kg) for 3 days prior to LPS injection. Twenty-four hours after lipopolysaccharide injection, the animals were sacrificed. Serum, liver, and kidney tissue samples were collected for biochemical analyses, histopathological examinations, and investigation of inflammation-related gene expression. OLE pretreatment significantly reduced liver damage parameters (alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase) and kidney damage parameters (blood urea nitrogen, creatinine, and kidney injury molecule-1) in the septic mice. OLE pretreatment ameliorated LPS-induced liver and kidney histological changes. OLE significantly mitigated the increased levels of malondialdehyde in the liver and kidneys and reduced levels of reduced glutathione induced by LPS. LPS injection also resulted in increased expression of the proinflammatory cytokines (TNF-α, IL-1β, and IL-6) and inflammation-related genes (Nos2, Hmgb1, Mpo, Cd46, Map2k4, and Map2k7) in the hepatic and renal tissues. OLE reduced these expressions to ameliorate the inflammatory response. Moreover, OLE pretreatment enhanced the survival rate of septic mice. In conclusion, OLE alleviated the inflammatory response to protect against LPS-induced sepsis in mice.

Is Extra Virgin Olive Oil an Ally for Women's and Men's Cardiovascular Health?

Noncommunicable diseases are long-lasting and slowly progressive and are the leading causes of death and disability. They include cardiovascular diseases (CVD) and diabetes mellitus (DM) that are rising worldwide, with CVD being the leading cause of death in developed countries. Thus, there is a need to find new preventive and therapeutic approaches. Polyphenols seem to have cardioprotective properties; among them, polyphenols and/or minor polar compounds of extra virgin olive oil (EVOO) are attracting special interest. In consideration of numerous sex differences present in CVD and DM, in this narrative review, we applied "gender glasses." Globally, it emerges that olive oil and its derivatives exert some anti-inflammatory and antioxidant effects, modulate glucose metabolism, and ameliorate endothelial dysfunction. However, as in prescription drugs, also in this case there is an important gender bias because the majority of the preclinical studies are performed on male animals, and the sex of donors of cells is not often known; thus a sex/gender bias characterizes preclinical research. There are numerous clinical studies that seem to suggest the benefits of EVOO and its derivatives in CVD; however, these studies have numerous limitations, presenting also a considerable heterogeneity across the interventions. Among limitations, one of the most relevant in the era of personalized medicine, is the non-attention versus women that are few and, also when they are enrolled, sex analysis is lacking. Therefore, in our opinion, it is time to perform more long, extensive and lessheterogeneous trials enrolling both women and men.

The effect of oleuropein on unilateral ureteral obstruction induced-kidney injury in rats: the role of oxidative stress, inflammation and apoptosis

Unilateral ureteral obstruction (UUO) induces kidney injury. Oleuropein as a major compound of olive leaves modulates the inflammatory parameters and decreases oxidative stress. Accordingly, we evaluate the renoprotective effect of oleuropein against 3-day UUO rats. Forty rats were randomly divided into five groups (n = 8) including control, UUO and UUO + oleuropein groups (50, 100 and 200 mg/kg). UUO model was induced by left ureter ligation and continued for 3-day. Rats were treated synchronic daily for 3-day, then mean arterial pressure (MAP), renal perfusion pressure (RPP), renal blood flow (RBF), serum creatinine level, and also superoxide dismutase (SOD), glutathione peroxidase (GPx) activity levels and malondialdehyde (MDA) concentration (in the obstructed kidney) were measured. The western blotting method was applied to evaluate the Bax, Bcl-2, cleaved caspase-3 and TNF-α proteins expression level. The hematoxylin and eosin method was applied to evaluate the kidney tissue damage score (KTDS). UUO significantly increased RVR, KTDS, and MDA, cleaved caspase-3, Bax, serum creatinine and TNF-α protein levels (P < 0.05), and also significantly decreased RBF, SOD, and GPx and Bcl-2 protein expression levels (P < 0.001) in the obstructed kidney and oleuropein (200 mg/kg) significantly ameliorated the changes induced by UUO. Our findings showed that oleuropein has a renoprotective effect against 3-day UUO. The mechanisms underlying the observed effects may be related to its antioxidative stress, anti-apoptotic, and anti-inflammatory effects.

UV-Vis Spectroelectrochemistry of Oleuropein, Tyrosol, and p-Coumaric Acid Individually and in an Equimolar Combination. Differences in LC-ESI-MS2 Profiles of Oxidation Products and their Neuroprotective Properties

Major phenolic compounds from olive oil (ArOH-EVOO), oleuropein (Ole), tyrosol (Tyr), and p-coumaric acid (p-Cou), are known for their antioxidant and neuroprotective properties. We previously demonstrated that their combination could potentiate their antioxidant activity in vitro and in cellulo. To further our knowledge of their electron-transfer properties, Ole, Tyr, and p-Cou underwent a spectroelectrochemical study, performed either individually or in equimolar mixtures. Two mixtures (Mix and Mix-seq) were prepared in order to determine whether distinct molecules could arise from their simultaneous or sequential oxidation. The comparison of Liquid Chromatography-Electrospray Ionization-Tandem Mass Spectrometry (LC-ESI-MS2) profiles highlighted the presence of specific oxidized products found in the mixes. We hypothesized that they derived from the dimerization between Tyr and Ole or p-Cou, which have reacted either in their native or oxidized forms. Moreover, Ole regenerates when the Mix undergoes oxidation. Our study also showed significant neuroprotection by oxidized Ole and oxidized Mix against H2O2 toxicity on SK-N-SH cells, after 24 h of treatment with very low concentrations (1 and 5 nM). This suggests the putative relevant role of oxidized Ole products to protect or delay neuronal death.

Oleuropein, a Bioactive Compound from Olea europaea L., as a Potential Preventive and Therapeutic Agent in Non-Communicable Diseases

Growing scientific literature data suggest that the intake of natural bioactive compounds plays a critical role in preventing or reducing the occurrence of human chronic non-communicable diseases (NCDs). Oleuropein, the main phenolic component of Olea europaea L., has attracted scientific attention for its several health beneficial properties such as antioxidant, anti-inflammatory, cardio- and neuro-protective, and anti-cancer. This article is a narrative review focused on the current literature concerning the effect of oleuropein in NCDs, such as neuro- and cardiovascular diseases, diabetes mellitus, chronic kidney diseases, and cancer, by its putative antioxidant and anti-inflammatory activity, but also for its other peculiar actions such as an autophagy inducer and amyloid fibril growth inhibitor and, finally, for its anti-cancer effect. Despite the increasing number of published studies, looking at the beneficial effects of oleuropein, there is limited clinical evidence focused on the benefits of this polyphenol as a nutraceutical product in humans, and many problems are still to be resolved about its bioavailability, bioaccessibility, and dosage. Thus, future clinical randomized trials are needed to establish the relation between the beneficial effects and the mechanisms of action occurring in the human body in response to the intake of oleuropein.

Effect Of An Extra-Virgin Olive Oil Intake On The Delay Of Cognitive Decline: Role Of Secoiridoid Oleuropein?

Currently, there is an increase in the number of the world's aging population. This aging process is often connected with cognitive decline of some functions such as memory or speed processing loss. Since Alzheimer's disease cannot be cured yet, considerable efforts are being made to at least delay this cognitive decline among elderly in order to maintain and prolong the quality of their life. This can also be achieved by non-pharmacological approaches such as performing physical activities, cognitive training, or adhering to a Mediterranean Diet (MedDiet). One of the components of MedDiet - extra-virgin olive oil (EVOO) - has considerable health benefits. The purpose of this review is to examine the effect of EVOO intake on the delay of cognitive decline among the elderly. The methodology is based on a literature review of available sources found on the research topic in three acknowledged databases: Web of Science, Scopus, and PubMed. The results of in vitro and in vivo studies indicate that the regular intake of EVOO is associated with enhanced cognitive functions, which means that this oil may have a neuroprotective effect and could positively prevent the development of dementia, especially Alzheimer's dementia. It is believed that secoiridoid oleuropein is responsible for this effectiveness. Furthermore, there is also a need of more randomized controlled studies or longitudinal observational studies to be performed to confirm the efficacy of the beneficial health effect of EVOO on the delay of cognitive decline.

Antioxidative Effects of Olive Polyphenols Compared to Vitamin E in Piglets Fed a Diet Rich in N-3 PUFA

The aim of the current study was to assess the antioxidative effects of the dietary supplementation of olive leaf extract (OLE) in different concentrations compared to those of vitamin E in piglets under conditions of dietary n-3 PUFA-induced oxidative stress. Forty-eight castrated male piglets (10.6 ± 0.99 kg) were fed the following experimental diets: Cont- (low-fat diet, no supplement), Cont+ (high linseed oil diet, no supplement), Vit-E (as Cont+, 105 IU vitamin E/day), OLE-1 (as Cont+, 3.84 mg hydroxytyrosol equivalents (HEQs)/day), OLE-2 (as Cont+, 38.4 mg HEQ/day), and OLE-3 (as Cont+, 96 mg HEQ/day). After 21 days of feeding, the experimental diets, blood and urine samples were collected to assess the extent of the oxidative stress. Results indicated that diet OLE-1 lowered the activity of gamma-glutamyl transferase, protected DNA (measured as DNA tail %) and altered urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG). Dietary vitamin E lowered the levels of urinary F2-isoprostanes, as well as of plasma malondialdehyde and γ-tocopherol, but raised the plasmatic α-tocopherol and altered the level of urinary 8-OHdG. In conclusion, only minor positive effects of dietary OLE on the oxidative stress parameters were observed. Additionally, OLE did not show concentration dependence.

Effects of Virgin Olive Oils Differing in Their Bioactive Compound Contents on Biomarkers of Oxidative Stress and Inflammation in Healthy Adults: A Randomized Double-Blind Controlled Trial

A regular consumption of virgin olive oil (VOO) is associated with a reduced risk of cardiovascular disease. We aimed to assess whether the raw intake of an optimized VOO (OVOO, 490 ppm of phenolic compounds and 86 ppm of triterpenes), and a functional olive oil (FOO, 487 ppm of phenolic compounds and enriched with 389 ppm of triterpenes) supplementation (30 mL per day) during three weeks would provide additional health benefits to those produced by a standard VOO (124 ppm of phenolic compounds and 86 ppm of triterpenes) on oxidative and inflammatory biomarkers. Fifty-one healthy adults participated in a randomized, crossover, and controlled study. Urinary 8-hidroxy-2′-deoxyguanosine, plasma interleukin-8 (IL-8), and tumor necrosis factor α (TNF- α) concentrations were lower after the intervention with the FOO than after the OVOO (p = 0.033, p = 0.011 and p = 0.020, respectively). In addition, IL-8 was lower after the intervention with FOO than after VOO intervention (p = 0.002). This study provides a first level of evidence on the in vivo health benefits of olive oil triterpenes (oleanolic and maslinic acids) in healthy humans, decreasing DNA oxidation and plasma inflammatory biomarkers. The trial was registered in ClinicalTrials.gov ID: NCT02520739.

Network Meta-Analysis of Metabolic Effects of Olive-Oil in Humans Shows the Importance of Olive Oil Consumption With Moderate Polyphenol Levels as Part of the Mediterranean Diet

The beneficial role of olive oil consumption is nowadays widely recognized. However, it is not clear whether its health effects are due to the presence of monounsaturated lipids and/or to the antioxidant fraction of microconstituents present in olive oil. The aim of the present study was to analyze the exact role of olive oil in the modification of metabolic factors (glucose and circulating lipids) and explore the role of its antioxidant polyphenols. In the present work, we have performed a network meta-analysis of 30 human intervention studies, considering direct and indirect interactions and impact of each constituent. Interestingly, we show that the impact of olive oil on glucose, triglycerides, and LDL-cholesterol is mediated through an adherence to the Mediterranean diet, with the only notable effect of olive oil polyphenols being the increase of HDL-cholesterol, and the amelioration of the antioxidant and inflammatory status of the subjects. Additionally, we report for the first time that lower antioxidant polyphenol levels may be sufficient for the beneficial effects of olive oil, while we show that the lipid fraction of olive oil may be responsible for some of its beneficial actions. In all parameters examined the beneficial effect of olive oil was more pronounced in subjects with an established metabolic syndrome or other chronic conditions/diseases. In conclusion, all these findings provide new knowledge that could lead to re-establishment of the role of olive oil in human nutrition.

The beneficial effect of natural antioxidants from olive oil with fig and date palm fruit extracts on biochemical and hematological parameters in rats during diethylnitrosamine-induced carcinogenesis

Diethylnitrosamine (DEN) is a well-known carcinogen. The aim of our study was to determine the role of olive oil (7 g/kg) with fig (1 g/kg) (OF) and (or) date palm (1 g/kg) (D) fruit extracts during DEN treatment of male Wistar rats. The OF–DEN and (or) D–DEN groups were given oral antioxidants daily for two weeks before and during DEN treatment (21 weeks).

The DEN-treated group showed dramatic results for all investigated parameters as compared with the control rats. All OF–DEN and D–DEN groups showed significant improvement in hepatic thiobarbituric acid reactive substances, reduced glutathione, and nitric oxide concentration in the liver tissue, in addition to improvement in serum vascular endothelial growth factor level, alpha-fetoprotein, lipid profile, lipid risk ratios, and the hematological parameters as compared with the DEN-treated group.

In conclusion, the administration of OF and (or) D fruit extracts to DEN-treated rats resulted in a considerable improvement in the investigated biochemical and hematological parameters. In addition, the combined OFD treatments showed greater improvements revealing the synergistic effect of the combination.

Structure Properties, Acquisition Protocols, and Biological Activities of Oleuropein Aglycone

Oleuropein aglycone, which is the major phenolic component of extra virgin olive oil, is gaining popularity and importance in scientific and public communities. This paper summarizes the structure properties, acquisition protocols, and biological activities of oleuropein aglycone. There are three hydrolytic methods used to obtain oleuropein aglycone from oleuropein-enzymatic hydrolysis, acid hydrolysis, and acetal hydrolysis. Enzymatic hydrolysis can be achieved with exogenous enzymes and endogenous enzymes. In addition, the diverse pharmacological effects of oleuropein aglycone are summaried. These pharmacological effects include anti-Alzheimer's disease, anti-breast cancer, anti-inflammatory, anti-hyperglycemic, anti-oxidative, and lipid-lowering properties. Therefore, we can use hydrolysis and biological activities to study oleuropein aglycone in the future.

Strategies to decrease oxidative stress biomarker levels in human medical conditions: A meta-analysis on 8-iso-prostaglandin F2α

The widespread detection of elevated oxidative stress levels in many medical conditions has led to numerous efforts to design interventions to reduce its effects. Efforts have been wide-ranging, from dietary changes to administration of antioxidants, supplements, e.g., omega-3-fatty acids, and many medications. However, there is still no systemic assessment of the efficacy of treatments for oxidative stress reduction across a variety of medical conditions. The goal of this meta-analysis is, by combining multiple studies, to quantitate the change in the levels of the popular oxidative stress biomarker 8-iso-prostaglandin F2α (8-iso-PGF2α) after a variety of treatment strategies in human populations. Nearly 350 unique publications with 180 distinct strategies were included in the analysis. For each strategy, the difference between pre- or placebo and post-treatment levels calculated using Hedges' g value of effect. In general, administration of antibiotics, antihyperlipidemic agents, or changes in lifestyle (g = - 0.63, - 0.54, and 0.56) had the largest effect. Administration of supplements, antioxidants, or changes in diet (g = - 0.09, - 0.28, - 0.12) had small quantitative effects. To fully interpret the effectiveness of these treatments, comparisons to the increase in g value for each medical condition is required. For example, antioxidants in populations with coronary artery disease (CAD) reduce the 8-iso-PGF2α levels by g = - 0.34 ± 0.1, which is quantitatively considered a small effect. However, CAD populations, in comparison to healthy populations, have an increase in 8-iso-PGF2α levels by g = 0.38 ± 0.04; therefore, the overall reduction of 8-iso-PGF2α levels is ≈ 90% by this treatment in this specific medical condition. In conclusion, 8-iso-PGF2α levels can be reduced not only by antioxidants but by many other strategies. Not all strategies are equally effective at reducing 8-iso-PGF2α levels. In addition, the effectiveness of any strategy can be assessed only in relation to the medical condition investigated.

Critical Review on the Significance of Olive Phytochemicals in Plant Physiology and Human Health

Olive oil displays remarkable organoleptic and nutritional features, which turn it into a foodstuff appreciated by consumers, and a basic component of the Mediterranean diet. Indeed, the noticed benefits of including olive oil in the diet have been assigned to the presence of diverse bioactive compounds with different molecular structures. These compounds confer a wide range of biological properties to this food matrix, including the prevention of distinct human diseases as well as the modulation of their severity. The most relevant bioactive compounds present in olive oil correspond to benzoic and cinnamic acids, phenolic alcohols and secoiridoids, and also flavonoids. Over the last decades, several studies, devoted to gaining a further insight into the relative contribution of the separate groups and individual compounds for their biological activities, have been conducted, providing relevant information on structure-activity relationships. Therefore, this paper critically reviews the health benefits evidenced by distinct phenolic compounds found in olive oils, thus contributing to clarify the relationship between their chemical structures and biological functions, further supporting their interest as essential ingredients of wholesome foods.

A Mediterranean Diet Reduces F2-Isoprostanes and Triglycerides among Older Australian Men and Women after 6 Months

Background: Health benefits of a Mediterranean dietary pattern have been shown. However, there are few data on the effects of increased adherence to a Mediterranean diet (MedDiet) in non-Mediterranean countries.Objective: We aimed to determine whether adherence to a MedDiet would result in changes in plasma lipids, glucose and insulin, high-sensitivity C-reactive protein (hs-CRP), and F₂-isoprostanes (F₂-IsoPs) in an Australian population.Methods: The study was a 6-mo parallel, randomized, controlled dietary intervention trial. We recruited 166 participants aged ≥65 y. Participants were stratified on body mass index, sex, and age and assigned to receive either a MedDiet or a habitual diet (HabDiet). The primary outcome was cognitive function, reported elsewhere. As secondary outcomes, assessment of fasting total, LDL, and HDL cholesterol; triglycerides (TGs); glucose; insulin; hs-CRP; and F₂-IsoPs was completed at baseline and at 3 and 6 mo. The MedDiet group followed a prescribed diet containing 15-45 mL extra-virgin olive oil/d, abundant vegetables, fruit, nuts, legumes, and whole grains, as well as moderate fish, poultry, and dairy foods. Dietary intake was measured by 3-d weighed food records at baseline and at 2 and 4 mo. Results were analyzed by using linear mixed-effects models.Results: Compared with the HabDiet, the MedDiet resulted in lower TGs at 3 mo (mean difference: -0.15 mmol/L; 95% CI: -0.23, -0.07 mmol/L; P < 0.001) and 6 mo (mean difference: -0.09 mmol/L; 95% CI: -0.18, -0.01 mmol/L; P = 0.03) and lower F₂-IsoPs at 3 mo (mean difference: -103.5 pmol/L; 95% CI: -154.2, -52.7 pmol/L; P < 0.001) and 6 mo (-65.4 pmol/L; 95% CI: -117.1, -13.7 pmol/L; P < 0.001). Lipoprotein, glucose and insulin, and hs-CRP concentrations were not significantly different between groups.Conclusion: A high adherence to a MedDiet for 6 mo resulted in a significant reduction in TGs and F₂-IsoPs among older Australians. This trial was registered at clinicaltrials.gov as ACTRN12613000602729.

Safety of hydroxytyrosol as a novel food pursuant to Regulation (EC) No 258/97

Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver an opinion on hydroxytyrosol, which is chemically synthesised, as a novel food (NF) pursuant to Regulation (EC) No 258/97. The information provided on the composition, specifications, batch-to-batch variability, stability and production process of the NF is sufficient and does not raise concerns about the safety of the NF. The applicant intends to add hydroxytyrosol to fish and vegetable oils up to 215 mg/kg and to margarines up to 175 mg/kg. The target group is the general population which excludes children under 36 months of age, pregnant women and breastfeeding women. Considering the no observed adverse effect level (NOAEL) of 50 mg/kg body weight per day from a subchronic oral toxicity study with the NF and the maximum anticipated daily intake for the NF, the margin of exposure (MoE) would result in 100 for children (3-9 years of age) and at least 200 for adolescents, adults (excluding pregnant and breastfeeding women) and elderly. Taking into account that the anticipated daily intake of the NF would be in the range of or even less than the exposure of hydroxytyrosol from the consumption of olive oils and olives, which has not been associated with adverse effects, and considering the similar kinetics of hydroxytyrosol in rats and humans, the Panel considers that the MoE for the NF at the intended uses and use levels is sufficient for the target population. The Panel concludes that the novel food, hydroxytyrosol, is safe under the proposed uses and use levels.

Oleuropein attenuates cognitive dysfunction and oxidative stress induced by some anesthetic drugs in the hippocampal area of rats

The present study was designed to evaluate the antioxidant effects of oleuropein against oxidative stress in the hippocampal area of rats. We used seven experimental groups as follows: Control, Propofol, Propofol-Ketamine (Pro.-Ket.), Xylazine-Ketamine (Xyl.-Ket.), and three oleuropein-pretreated groups (Ole.-Pro., Ole.-Pro.-Ket. and Ole.-Xyl.-Ket.). The oleuropein-pretreated groups received oleuropein (15 mg/kg body weight as orally) for 10 consecutive days. Propofol 100 mg/kg, xylazine 3 mg/kg, and ketamine 75 mg/kg once as ip was used on the 11th day of treatment. Spatial memory impairment and antioxidant status of hippocampus were measured via Morris water maze, lipid peroxidation marker, and antioxidant enzyme activities. Spatial memory impairment and lipid peroxidation significantly increased in Xyl.-Ket.-treated rats in comparison to the control, propofol, Ole.-Pro. and Ole.-Pro.-Ket. groups. Oleuropein pretreatment significantly reversed spatial memory impairment and lipid peroxidation in the Ole.-Xyl.-Ket. group as compared to the Xyl.-Ket.-treated rats. There was no significant difference between the control and the propofol group in lipid peroxidation and spatial memory status. Superoxide dismutase and catalase activities both significantly decreased in Xyl.-Ket.-treated rats when compared to the control, propofol, Ole.-Pro., Ole.-Pro.-Ket., and Ole.-Xyl.-Ket. groups. In contrast, glutathione peroxidase activity in Xyl.-Ket.-treated rats significantly increased as compared to the control, propofol, Pro.-Ket., Ole.-Pro., and Ole.-Pro.-Ket. groups. We concluded that xylazine in combination with ketamine is an oxidative anesthetic drug and oleuropein pretreatment attenuates cognitive dysfunction and oxidative stress induced by anesthesia in the hippocampal area of rats. We also confirmed the antioxidant properties of propofol as a promising antioxidant anesthetic agent.

Hydroxytyrosol supplementation increases vitamin C levels in vivo. A human volunteer trial

Hydroxytyrosol (HT) is a main phenolic component of olive oil. In this study, we investigated the safety and effects produced by HT purified (99.5%) from olive mill waste. HT was administered at a daily dosage of 45 mg for 8 weeks to volunteers with mild hyperlipidemia (n=14). We measured markers of cardiovascular disease risk, enzyme markers of several clinical conditions, hematology, antioxidant parameters, vitamins and minerals at baseline (T0), 4 weeks (T4) and 8 weeks (T8). The values obtained at T4 and T8 were compared with baseline. We found that the HT dose administered was safe and mostly did not influence markers of cardiovascular disease, blood lipids, inflammatory markers, liver or kidney functions and the electrolyte balance. Serum iron levels remained constant but a significant (P<0.05) decrease in ferritin at T4 and T8 was found. Serum folate and red blood cell folate levels were also reduced at T4 and T8. Finally, vitamin C increased by two-fold at T4 and T8 compared with levels at baseline. These results indicate a physiologically relevant antioxidant function for HT through increasing endogenous vitamin C levels.

Phenolic Compounds from Olea europaea L. Possess Antioxidant Activity and Inhibit Carbohydrate Metabolizing Enzymes In Vitro

Phenolic composition and biological activities of fruit extracts from Italian and Algerian Olea europaea L. cultivars were studied. Total phenolic and tannin contents were quantified in the extracts. Moreover 14 different phenolic compounds were identified, and their profiles showed remarkable quantitative differences among analysed extracts. Moreover antioxidant and enzymatic inhibition activities were studied. Three complementary assays were used to measure their antioxidant activities and consequently Relative Antioxidant Capacity Index (RACI) was used to compare and easily describe obtained results. Results showed that Chemlal, between Algerian cultivars, and Coratina, among Italian ones, had the highest RACI values. On the other hand all extracts and the most abundant phenolics were tested for their efficiency to inhibit α-amylase and α-glucosidase enzymes. Leccino, among all analysed cultivars, and luteolin, among identified phenolic compounds, were found to be the best inhibitors of α-amylase and α-glucosidase enzymes. Results demonstrated that Olea europaea fruit extracts can represent an important natural source with high antioxidant potential and significant α-amylase and α-glucosidase inhibitory effects.

One-week administration of hydroxytyrosol to humans does not activate Phase II enzymes

The notion that (poly)phenols act as direct free radical scavengers is being challenged by mere chemical and biochemical considerations such as bioavailability and intracellular concentrations. An alternative hypothesis that is gaining considerable traction is that (poly)phenols are processed by the body as xenobiotics via the Keap1/Nrf2/ARE signaling axis, leading to the induction of Phase II enzymes. However, there are no solid human data to confirm this interesting supposition. In this study, we tested the activities of hydroxytyrosol (HT) on Phase II enzymes' expression in a double-blind, randomized, placebo-controlled study. We tested two HT doses, i.e. 5 and 25mg/d, vs. placebo following a Latin square design. We report that HT is well tolerated but does not significantly modify Phase II enzyme expression in peripheral blood mononuclear cells. Moreover, we were unable to record significant effects on a variety of surrogate markers of cardiovascular disease such as lipid profile and inflammation and oxidation markers. Available evidence indicates that the "hormesis hypothesis" that (poly)phenols activate Phase II enzymes requires solid human confirmation that might be provided by future trials. This study is registered at ClinicalTrials.gov (identifier: NCT02273622).

Special Issue on "Analytical Methods for Oxidized Biomolecules and Antioxidants" The use of isoprostanoids as biomarkers of oxidative damage, and their role in human dietary intervention studies

Isoprostanoids are a group of non-enzymatic oxidized lipids from polyunsaturated fatty acids. They are commonly used as biomarkers for oxidative damage, to assess in vivo lipid peroxidation in diseases related to the vascular system and neurodegeneration. Currently, there is a mismatch with the outcome in the use of these biomarkers in intervention studies, particularly when testing the effect of antioxidants such as vitamins C and E, or zinc, or a cocktail of these, with other food components. Much of this is because the biomarkers, the method of measurement, and the duration of supplementation are unsuitable. In this review, we will highlight the formation of isoprostanoids from their respective fatty acids, and their application as biomarkers for oxidative damage in vivo, considering human dietary intervention studies evaluating plasma and urine, using mass spectrometry techniques.

Oleuropein induced apoptosis in HeLa cells via a mitochondrial apoptotic cascade associated with activation of the c-Jun NH2-terminal kinase

Oleuropein could inhibit growth and/or induce apoptosis in several cancer cell lines. In this study, we investigate how oleuropein strongly induces apoptotic cell death in HeLa human cervical carcinoma cells. Oleuropein induced HeLa cells apoptosis as demonstrated by induction of a sub-G(1) peak in flow cytometry and apoptosis-related morphological changes observed by fluorescence microscopy after being stained by Hoechst 33324. The results also showed that 150 - 200 μM oleuropein&ndash;treated HeLa cells were arrested at the G(2)/M phase. Western blot analysis revealed that the phosphorylated ATF-2, c-Jun NH(2)-terminal kinase (JNK) protein, p53, p21, Bax, and cytochrome c protein in the cytoplasm significantly increased in a dose-dependent manner after treatment of oleuropein for 24 h. Additionally, increasing levels of Bax in response to JNK/SPAK signaling, which formed mitochondrial membrane channels, accounted for releasing of cytochrome c and activation of caspase-9 and -3. SP600125 (20 μM), a JNK(1/2) inhibitor, markedly suppressed the formation of apoptotic bodies and JNK activation induced by oleuropein at 200 μM. Thus, oleuropein-induced apoptosis was activated by the JNK/SPAK signal pathway. The result shows that oleuropein holds promise as a potential chemotherapeutic agent for the treatment of HeLa cells.

Effects of the olive-derived polyphenol oleuropein on human health

The use of the products derived from the olive tree on human health dates back centuries. In several civilizations, the olive tree had and still has a very strong cultural and religious symbolism. Notably, the official seal and emblem of the World Health Organization features the rod of Asclepius over a world map surrounded by olive tree branches, chosen as a symbol of peace and health. Recently, accumulating experimental, clinical and epidemiological data have provided support to the traditional beliefs of the beneficial effect provided by olive derivates. In particular, the polyphenols present in olive leaves, olives, virgin (unrefined) olive oil and olive mill waste are potent antioxidant and radical scavengers with anti-tumor and anti-inflammatory properties. Here, we review the positive impact on human health of oleuropein, the most prevalent polyphenol present in olives. In addition, we provide data collected in our laboratory on the role of oleuropein in counteracting lipid accumulation in a mouse model of non-alcoholic fatty liver disease.

Chronic hydroxytyrosol feeding modulates glutathione-mediated oxido-reduction pathways in adipose tissue: a nutrigenomic study

BACKGROUND AND AIM

Hydroxytyrosol (HT) is the most prominent phenolic component of olives, olive oil, and their by-products, e.g. olive mill waste water. As the link between HT consumption (via extra virgin olive oil intake) and better cardiovascular prognosis is being scientifically validated, HT is entering the market as a potentially useful supplement for cardiovascular disease prevention. One of the target organs in cardiometabolic prevention is the adipose tissue, where inflammation, oxidative stress, and secretion of adipocytokines contribute to cardiovascular risk.

METHODS AND RESULTS

We explored the nutrigenomic effects of long-term supplementation with nutritionally-relevant doses of HT, i.e. 0.03 gm% - with specific reference to the adipose tissue and glutathione metabolism - and we explored underlying mechanisms in vitro. We show that HT modulates the antioxidant network in the adipose tissue, as mediated by glutathione (GSH) and associated enzymes. We also confirmed the GSH-modulating activities of HT in cultured adipocytes, where low, physiological HT concentrations were able to blunt the H2O2-induced GSH/GSSG alteration indicative of oxidative stress. In terms of surrogate markers of cardiovascular disease, we recorded significantly decreased circulating leptin concentrations in mice fed with HT as compared with controls.

CONCLUSIONS

HT - in nutritionally relevant amounts - is able to positively modulate the glutathione-driven antioxidant enzymatic machinery in the adipose tissue. Because HT is generally recognized as safe (GRAS) and exhibits an excellent safety profile in vitro and in vivo, its future employment as adjunct treatment of metabolic syndrome can be envisioned, pending specific trials.

Effects of maternal dietary olive oil on pathways involved in diabetic embryopathy

Maternal diabetes induces a pro-oxidant/pro-inflammatory intrauterine environment related to the induction of congenital anomalies. Peroxisome proliferator activated receptors (PPARs) are transcription factors that regulate antioxidant and anti-inflammatory pathways. We investigated whether maternal diets supplemented with olive oil, enriched in oleic acid, a PPAR agonist, can regulate the expression of PPAR system genes, levels of lipoperoxidation and activity of matrix metalloproteinases (MMPs) and their endogenous inhibitors (TIMPs) in embryos and decidua from diabetic rats. The embryos and decidua from diabetic rats showed reduced expression of PPARs and increased concentration of lipoperoxidation, MMPs and TIMPs, whereas the maternal treatments enriched in olive oil increased PPARδ in embryos and PPARγ and PPARγ-coactivator-1α expression in decidua, and increased TIMPs concentrations and decreased lipoperoxidation and MMPs activity in both tissues. Thus, maternal diets enriched in olive oil can regulate embryonic and decidual PPAR system genes expression and reduce the pro-oxidant/pro-inflammatory environment during rat early organogenesis.

The effects of oleuropein aglycone, an olive oil compound, in a mouse model of carrageenan-induced pleurisy

BACKGROUND & AIMS

Several olive oil phenolic compounds, such us oleuropein have attracted considerable attention because of their antioxidant activity, anti-atherosclerotic and anti-inflammatory properties. The aim of this study was to investigate the effects of oleuropein aglycone, a hydrolysis product of oleuropein, in a mouse model of carrageenan-induced pleurisy.

METHODS

Mice were anaesthetized and subjected to a skin incision at the level of the left sixth intercostals space. The underlying muscle was dissected and saline or saline containing 2% λ-carrageenan was injected into the pleural cavity.

RESULTS

Injection of carrageenan elicited an acute inflammatory response characterized by: infiltration of neutrophils in lung tissues (P < 0.01 versus sham. P < 0.01 versus carrageenan) and subsequent lipid peroxidation (P < 0.01 versus sham. P < 0.01 versus carrageenan), increased production of tumor necrosis factor-α and interleukin-1β (P < 0.01 versus sham. P < 0.01 versus carrageenan), increased expression of adhesion molecules, increased synthesis of nitric oxide (P < 0.01 versus sham. P < 0.01 versus carrageenan), nitrotyrosine and poly-ADP-ribose (P < 0.01 versus sham. P < 0.01 versus carrageenan). Administration of oleuropein aglycone 30 min after the challenge with carrageenan, caused a significant reduction of all the parameters of inflammation measured.

CONCLUSIONS

Thus, we propose that olive oil phenolic constituents may be useful in the treatment of various inflammatory diseases.

Urinary metabolites as biomarkers of polyphenol intake in humans: a systematic review

BACKGROUND

To identify associations between polyphenol intake and health and disease outcomes in cohort studies, it is important to identify biomarkers of intake for the various compounds commonly consumed as part of the diet.

OBJECTIVE

The objective of this systematic review was to assess the usefulness of polyphenol metabolites excreted in urine as biomarkers of polyphenol intake in humans.

DESIGN

The method included a structured search strategy for polyphenol intervention studies on Ovid MEDLINE, EMBASE (Ovid), and Cochrane databases; formal inclusion and exclusion criteria; data extraction into an Access database; validity assessment; and meta-analysis.

RESULTS

One hundred sixty-two controlled intervention studies with polyphenols were included, and mean recovery yield and correlations with the dose ingested were determined for 40 polyphenols. Polyphenols such as daidzein, genistein, glycitein, enterolactone, and hydroxytyrosol showed both a high recovery yield (12-37%) and a high correlation with the dose (Pearson's correlation coefficients: 0.67-0.87), which showed good sensitivity and robustness as biomarkers of intake throughout the different studies. Weaker recovery for anthocyanins (0.06-0.2%) and weaker correlations with dose [Pearson's correlation coefficients: 0.21-0.52 for hesperidin, naringenin, (-)-epicatechin, (-)-epigallocatechin, quercetin, and 3 microbial metabolites of isoflavones (dihydrodaidzein, equol, and O-desmethylangolensin)] suggest that they are currently less suitable as biomarkers of intake.

CONCLUSIONS

These data confirm the value of certain urinary polyphenols as biomarkers of intake. A validation in populations is now needed to evaluate their specificity, sensitivity, and responsiveness to dose under free-living conditions.

Limited effect of dietary saturated fat on plasma saturated fat in the context of a low carbohydrate diet

We recently showed that a hypocaloric carbohydrate restricted diet (CRD) had two striking effects: (1) a reduction in plasma saturated fatty acids (SFA) despite higher intake than a low fat diet, and (2) a decrease in inflammation despite a significant increase in arachidonic acid (ARA). Here we extend these findings in 8 weight stable men who were fed two 6-week CRD (12%en carbohydrate) varying in quality of fat. One CRD emphasized SFA (CRD-SFA, 86 g/d SFA) and the other, unsaturated fat (CRD-UFA, 47 g SFA/d). All foods were provided to subjects. Both CRD decreased serum triacylglycerol (TAG) and insulin, and increased LDL-C particle size. The CRD-UFA significantly decreased plasma TAG SFA (27.48 ± 2.89 mol%) compared to baseline (31.06 ± 4.26 mol%). Plasma TAG SFA, however, remained unchanged in the CRD-SFA (33.14 ± 3.49 mol%) despite a doubling in SFA intake. Both CRD significantly reduced plasma palmitoleic acid (16:1n-7) indicating decreased de novo lipogenesis. CRD-SFA significantly increased plasma phospholipid ARA content, while CRD-UFA significantly increased EPA and DHA. Urine 8-iso PGF_2α, a free radical-catalyzed product of ARA, was significantly lower than baseline following CRD-UFA (−32%). There was a significant inverse correlation between changes in urine 8-iso PGF_2α and PL ARA on both CRD (r = −0.82 CRD-SFA; r = −0.62 CRD-UFA). These findings are consistent with the concept that dietary saturated fat is efficiently metabolized in the presence of low carbohydrate, and that a CRD results in better preservation of plasma ARA.

Cardioprotective and neuroprotective roles of oleuropein in olive

Traditional diets of people living in the Mediterranean basin are, among other components, very rich in extra-virgin olive oil, the most typical source of visible fat. Olive is a priceless source of monounsaturated and di-unsaturated fatty acids, polyphenolic antioxidants and vitamins. Oleuropein is the main glycoside in olives and is responsible for the bitter taste of immature and unprocessed olives. Chemically, oleuropein is the ester of elenolic acid and 3,4-dihydroxyphenyl ethanol, which possesses beneficial effects on human health, such as antioxidant, antiatherogenic, anti-cancer, anti-inflammatory and antimicrobial properties. The phenolic fraction extracted from the leaves of the olive tree, which contains significant amounts of oleuropein, prevents lipoprotein oxidation. In addition, oleuropein has shown cardioprotective effect against acute adriamycin cardiotoxicity and an anti-ischemic and hypolipidemic activities. Recently, oleuropein has shown neuroprotection by forming a non-covalent complex with the Aβ peptide, which is a key hallmark of several degenerative diseases like Alzheimer and Parkinson. Thus, a large mass of research has been accumulating in the area of olive oil, in the attempt to provide evidence for the health benefits of olive oil consumption and to scientifically support the widespread adoption of traditional Mediterranean diet as a model of healthy eating. These results provide a molecular basis for some of the benefits potentially coming from oleuropein consumption and pave the way to further studies on the possible pharmacological use of oleuropein to prevent or to slow down the cardiovascular and neurodegenerative diseases.

Oleuropein in olive and its pharmacological effects

Olive from Olea europaea is native to the Mediterranean region and, both the oil and the fruit are some of the main components of the Mediterranean diet. The main active constituents of olive oil include oleic acid, phenolic constituents, and squalene. The main phenolic compounds, hydroxytyrosol and oleuropein, give extra-virgin olive oil its bitter, pungent taste. The present review focuses on recent works that have analyzed the relationship between the major phenolic compound oleuropein and its pharmacological activities including antioxidant, anti-inflammatory, anti-atherogenic, anti-cancer activities, antimicrobial activity, antiviral activity, hypolipidemic and hypoglycemic effect.

Olive oil phenols modulate the expression of metalloproteinase 9 in THP-1 cells by acting on nuclear factor-kappaB signaling

In vivo studies suggest that the phenolic component contributes to the anti-inflammatory and antiatherosclerotic actions of olive oil; however, the effects in circulating cells are not fully characterized. Monocytes play a key role in inflammation-based diseases by expressing several molecules, including metalloproteinases (MMPs). In the present study, we investigated the effects of olive oil phenolic extract and individual compounds on MMP-9 in THP-1 cells, a human monocyte-like cell line. Olive oil extract prevented the stimulation of MMP-9 expression and secretion in tumor necrosis factor alpha-treated THP-1 cells. Oleuropein aglycone, a typical olive oil phenol, was active at concentrations found in the extract, although other compounds probably contribute to the biological activity. We also found that the effect of the extract and individual compounds on MMP-9 is due to impaired nuclear factor-kappaB signaling. Our findings provide further evidence on the mechanisms by which olive oil reduces the inflammatory burden associated with disorders, such as atherosclerosis.