Phenolic Compounds In Virgin Olive Oil Research Articles

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.

The Composition of Volatiles and the Role of Non-Traditional LOX on Target Metabolites in Virgin Olive Oil from Autochthonous Dalmatian Cultivars.

The lipoxygenase pathway has a significant influence on the composition of the volatile components of virgin olive oil (VOO). In this work, the influence of the maturity index (MI) on the activity of the lipoxygenase enzyme (LOX) in the fruits of the autochthonous Dalmatian olive cultivars Oblica, Levantinka and Lastovka was studied. The analysis of the primary oxidation products of linoleic acid in the studied cultivars showed that LOX synthesises a mixture of 9- and 13-hydroperoxides of octadecenoic acid in a ratio of about 1:2, which makes it a non-traditional plant LOX. By processing the fruits of MI~3, we obtained VOOs with the highest concentration of desirable C6 volatile compounds among the cultivars studied. We confirmed a positive correlation between MI, the enzyme activity LOX and the concentration of hexyl acetate and hexanol in cultivars Oblica and Lastovka, while no positive correlation with hexanol was observed in the cultivar Levantinka. A significant negative correlation was found between total phenolic compounds in VOO and LOX enzyme activity, followed by an increase in the MI of fruits. This article contributes to the selection of the optimal harvest time for the production of VOOs with the desired aromatic properties and to the knowledge of the varietal characteristics of VOOs.

Extra Virgin Olive Oil Phenolic Compounds Modulate the Gene Expression of Biomarkers Involved in Fibroblast Proliferation and Differentiation.

Extra virgin olive oil phenolic compounds have been identified as possible biostimulant agents against different pathological processes, including alterations in healing processes. However, there is little evidence on the molecular mechanisms involved in this process. The aim was to analyse the effect of hydroxytyrosol, tyrosol, and oleocanthal on fibroblast gene expression. PCR was used to determine the expression of different differentiation markers, extracellular matrix elements, and growth factors in cultured human fibroblasts CCD-1064Sk treated with different doses of hydroxytyrosol (10-5 M and 10-6 M), tyrosol (10-5 M and 10-6 M), and oleocanthal (10-6 M and 10-7 M). After 24 h of hydroxytyrosol treatment, increased expression of connective tissue growth factor, fibroblast growth factor (FGF), platelet-derived growth factor, vascular endothelial growth factor, transforming growth factor β1 (TGF-β1), and their receptors was observed. Tyrosol and olecanthal modulated the expression of FGF and TGFβR1. All phytochemicals tested modified the expression of differentiation markers and extracellular matrix elements, increasing gene expression of actin, fibronectin, decorin, collagen I, and III. Phenolic compounds present in extra virgin olive could have a beneficial effect on tissue regeneration by modulating fibroblast physiology.

Nutrition during pregnancy and lactation: New evidence for the vertical transmission of extra virgin olive oil phenolic compounds in rats

Maternal breast milk provides the newborn with passive immunity and stimulates the maturation of the infant immune system. The aim of the present study was to evaluate the vertical transmission of phenolic compounds and their metabolites to offspring in rats fed with extra virgin olive oil (EVOO) during pregnancy and lactation. For this purpose, plasma and lactic serum from dams and plasma from offspring were analyzed by LC-ESI-LTQ-Orbitrap-MS. Both enzymatic and microbial metabolites of hydroxytyrosol and tyrosol were detected in dam plasma and lactic serum. In addition, significant levels of phenolic compounds and their metabolites were found in offspring plasma. The concentration and number of hydroxytyrosol derivatives was higher than those of tyrosol and the microbial metabolites were found in the highest concentration. The observed vertical transmission of EVOO phenolic compounds, whose health benefits are widely reported, provides further support for the importance of the maternal diet during pregnancy and lactation.

The Impact of Mild Frost Occurring at Different Harvesting Times on the Volatile and Phenolic Composition of Virgin Olive Oil.

The organoleptic characteristics of virgin olive oil (VOO), together with its nutritional and health properties, have led the olive tree to be cultivated beyond the Mediterranean basin, reaching latitudes with colder climates, with minimum temperatures below 0 °C and with a higher probability of early frosts. The freezing of olives generates destruction within the tissues and promotes degradation reactions. In this study, the impact of mild frost occurring at different harvesting times on the composition of volatiles and phenolic compounds in VOO were investigated. Arbequina variety olives were harvested at different stages of ripening. Half of the olives were subjected to oil extraction and the other half were frozen at −3 ± 1 °C for 12 h prior to oil extraction. A significant decrease of phenolic compounds with harvesting time was observed in both types of oils (fresh and frozen olives). Oils from frozen olives presented a slightly higher content of total phenols, except in the advanced ripening stage (September), and a slightly lower content of volatile compounds at all harvesting times. In addition, a higher content of 3,4-DHPEA-EDA was observed in oils from frozen olives, which is attributed to an early action of the endogenous β-glucosidase enzyme on oleuropein in freeze-damaged olive fruits. Principal component analysis and Discriminant Partial Least Square Regression allowed the oils to be classified according to the type of fruit (fresh and frozen) and the month of harvest. This study would indicate that mild frost would have a low impact on the chemical composition of virgin olive oil, although, this depends on the ripening stage.

Study on the interaction mechanism of virgin olive oil polyphenols with mucin and α-amylase

The interaction mechanism of mucin and α-amylase with virgin olive oil (VOO) polyphenols (oleuropein (OL), tyrosol (TY), hydroxytyrosol (HT)) was analyzed by fluorescence, ultraviolet (UV) absorption, attenuated total reflection Fourier transform infrared (ATR-FTIR), circular dichroic (CD) spectroscopy and molecular docking. A total of 17 polyphenols have been identified in the selected VOO, and the TY, HT and OL were the main compounds. The quenching mechanism between mucin/α-amylase and three VOO polyphenols was static, mainly through van der Waals forces and hydrogen bonds. The results of UV absorption, ATR-FTIR, and CD spectroscopy revealed that the conformation of mucin changed after combining with the three polyphenols, while that of the α-amylase changed little. Molecular docking predicted the interaction sites of the three polyphenols with human salivary mucin and α-amylase. The present study could provide the theoretical foundation for further research on the interaction between human salivary protein and phenolic compounds in VOO.

Metal nanoparticles based lab-on-paper for phenolic compounds evaluation with no sample pretreatment. Application to extra virgin olive oil samples

In this work, a low-cost, disposable, and portable lab-on-paper device is proposed to simultaneously quantify total polyphenol content (TPC) and antioxidant capacity (AOC) in 15 min; the assay requires no pre-treatment of the samples. The lab-on-paper device fabrication has been carried out employing a xurography-based benchtop microfabrication technology using low-cost materials as chromatography paper and polymeric sheets. Extra virgin olive oil (EVOO) phenolic compounds' represents a nutritional added value, nevertheless, the high lipidic content hinders their direct and rapid analysis, resulting in an extremely challenging sample. The realized lab-on-paper allows to perform the dual TPC and AOC determination in three simple steps: (i) sample loading, (ii) analytes transport to the analysis spot, and (iii) double colorimetric analysis exploiting the growth of AuNPs and AgNPs on paper mediated by phenolic compounds. Signal acquisition is achieved using a standard digital camera. The dual colorimetric assay is able to detect phenolic compounds in the 25–500 mg L−1 range with limits of detection ≤6 mg L−1 and good reproducibility (RSDs ≤11%). Direct analysis of EVOO samples (n = 30) correlated well (r > 0.92) with conventional spectrophotometric methods for TPC and AOC determination.

Effects of virgin olive oil phenolic compounds on health: solid evidence or just another fiasco?

Current research suggests that virgin olive oil (VOO) phenolics are potent preventive and therapeutic agents against metabolic diseases associated with inflammation and oxidative stress. Evidence-based medicine requires these effects be proved in randomized controlled trials (RCT), which are then assessed in meta-analyses, to ensure that the alleged health benefits really proceed in humans. The available evidence is limited to the ability of VOO phenolic compounds to protect lipoproteins from oxidation and to reduce systolic pressure in hypertensive individuals. No RCT assessing the effects of VOO phenolics on diabetes and neurodegenerative diseases have been performed, and those focused on osteoarthritis and cancer provided very scarce information. Therefore, RCT in extensive and diverse population groups, with different disorders and phenolic doses adjusted to usual VOO consumptions are necessary to achieve high quality scientific evidence before nutritional recommendations can be given to the general public.

Virgin Olive Oil Phenolic Compounds Modulate the HDL Lipidome in Hypercholesterolaemic Subjects: A Lipidomic Analysis of the VOHF Study.

ScopeThe lipidomic analysis of high‐density lipoprotein (HDL) could be useful to identify new biomarkers of HDL function.Methods and resultsA randomized, controlled, double‐blind, crossover trial (33 hypercholesterolaemic subjects) is performed with a control virgin olive oil (VOO), VOO enriched with its own phenolic compounds (FVOO), or VOO enriched with additional phenolic compounds from thyme (FVOOT) for 3 weeks. HDL lipidomic analyses are performed using the Lipidyzer platform. VOO and FVOO intake increase monounsaturated‐fatty acids (FAs) and decrease saturated and polyunsaturated FAs in triacylglyceride (TAG) species, among others species. In contrast, FVOOT intake does not induce these FAs changes. The decrease in TAG52:3(FA16:0) after VOO intake and the decrease in TAG52:5(FA18:2) after FVOO intake are inversely associated with changes in HDL resistance to oxidation. After FVOO intake, the decrease in TAG54:6(FA18:2) in HDL is inversely associated with changes in HDL cholesterol efflux capacity.ConclusionVOO and FVOO consumption has an impact on the HDL lipidome, in particular TAG species. Although TAGs are minor components of HDL mass, the observed changes in TAG modulated HDL functionality towards a cardioprotective mode. The assessment of the HDL lipidome is a valuable approach to identify and characterize new biomarkers of HDL function.

The phenolic profile of virgin olive oil is influenced by malaxation conditions and determines the oxidative stability

Phenolic compounds largely contribute to the nutraceutical properties of virgin olive oil (VOO), the organoleptic attributes and the shelf life due to their antioxidant capabilities. Due to the relevance of malaxation in the oil extraction process, we tested the effects of malaxation time on the concentrations of relevant phenolic compounds in VOO, and we evaluated the influence of performing malaxation under vacuum. An increase in malaxation time significantly decreased the concentrations of aglycone isomers of oleuropein and ligstroside but, conversely, increased the oleocanthal and oleacein contents. Additionally, malaxation under vacuum led to an increase in phenolic contents compared to standard conditions carried out at atmospheric pressure. Finally, we explored the possibility of predicting the VOO oxidative stability on the basis of the phenolic profile, and a model (R2 = 0.923; p < 0.0001) was obtained by combining the concentration of the VOO phenolic compounds and the main fatty acids.

Effect of olive oil phenolic compounds on the aroma release and persistence from O/W emulsion analysed in vivo by APCI-MS.

The effect of the presence of virgin olive oil (VOO) phenolic compounds was studied during the in-vivo consumption of an olive oil-in-water (O/W) food emulsion, assessed by APCI-MS. VOO phenolic compounds were present at 593 mg kg-1. Four volatile compounds, i.e. ethyl acetate, hexanal, hexanol and linalool, were monitored based on their physicochemical characteristics and their aroma impact. Olive O/W emulsions were stabilized by whey protein isolate (WPI) and xanthan gum. Our results suggested that ethyl acetate and hexanal have a "salting out" effect in the presence of VOO phenolics at swallowing of emulsion. Among the volatiles investigated, hexanal showed the highest release. The persistence in the breath was higher for linalool only, potentially due to its higher hydrophobicity. This study could be beneficial in the formulation of new functional foods to enhance aroma release and persistence in the presence of natural phenolic compounds.

Modulation of intestinal epithelium homeostasis by extra virgin olive oil phenolic compounds.

Dietary habits have been strongly linked to the maintenance of intestinal epithelium homeostasis, whose alteration may contribute to the pathogenesis of inflammatory diseases and cancer. Polyphenols are among those dietary components suggested to be beneficial for gut health. Within a balanced Mediterranean type diet, a good portion of ingested polyphenols comes from olives and extra virgin olive oil (EVOO). Most of them reach the intestine, where they may be directly absorbed or metabolized under absorption. Others undergo an extensive gastrointestinal biotransformation, producing various metabolites that retain the potential beneficial effect of the parent compounds, or exert a more efficient biological action themselves. Ingested EVOO polyphenols (EVOOP) and their metabolites will be particularly concentrated in the intestinal lumen, where they might exert a significant local action. In this review we summarize the few studies that investigated the effect of EVOOP at the intestinal level, focusing on the possible mechanism of action in relation to their interaction with the microbiota, and their ability to potentially modulate the oxidative status of the intestinal epithelial layer, inflammation and immune response.

Effect of olive cultivar on bioaccessibility and antioxidant activity of phenolic fraction of virgin olive oil.

This study aims to characterize the phenolic profile and antioxidant capacity of seven monovarietal virgin olive oils (VOOs) and evaluate their in vitro gastrointestinal stability. 'Picual', 'Blanqueta', 'Sevillana', 'Habichuelero', and 'Chetoui' olive cultivars were selected for VOO extraction. The oils were subjected to in vitro digestion. The recovery index (RI) of phenolic compounds after each digestion step and the bioaccessibility index (BI) were evaluated. In addition, the antioxidant activity of the bioaccessible fraction (BF) of VOOs was determined by DPPH, ABTS, and ORAC assays, as well as by studying the intracellular reactive oxygen species in Caco-2 cells. Differences were found in the composition of phenolic compounds in VOOs depending on cultivars. During the digestive process, important losses of phenolic compounds were observed between the buccal and duodenal steps, unlike HTy and Ty, which presented increased recovery due to the hydrolysis of secoiridoid derivatives. Differences in the bioaccessibility of phenolic compounds were found between varieties of VOOs. 'Sevillana' VOO had the highest total bioaccessibility (36%), followed by the 'Picual' (19%), 'Chetoui' (17%), 'Habichuelero' (10%), and 'Blanqueta' (8%) varieties. The BF of all the varieties of VOO showed similar radical ABTS scavenging capacity, 'Chetoui', and 'Blanqueta'-BF having the highest radical DPPH scavenging capacity, and 'Habichuelero' and 'Picual'-BF showing protective effects against the peroxyl radical measured by ORACFL assay. All VOO-BFs presented decreases in ROS levels in Caco-2 cells. Our results suggest differences in the bioaccessibility of phenolics from diverse VOO varieties, which could lead to different biological properties. Therefore, this study represents a first step toward the development of novel dietary strategies focusing on the phenolic supplementation of different VOOs to preserve human health.

Hydroxytyrosol and the Colonic Metabolites Derived from Virgin Olive Oil Intake Induce Cell Cycle Arrest and Apoptosis in Colon Cancer Cells.

After the sustained consumption of virgin olive oil (VOO), the unabsorbed native phenols (mainly hydroxytyrosol (HT)) are transformed into its catabolites in the intestine by microbials. The role of these catabolites in preventing colon cancer has not been sufficiently investigated. This work aims to study the antiproliferative and apoptotic activities in colon (Caco-2; HT-29) cancer cell lines of the main catabolites detected in human feces (phenylacetic, phenylpropionic, hydroxyphenylpropionic, and dihydroxyphenylpropionic acids and catechol), after the sustained VOO intake. Additionally, an assessment of the ability of these colonic cells to metabolize the studied compounds was performed. The results showed that HT and phenylacetic and hydroxyphenylpropionic acids produce cell cycle arrest and promote apoptosis. HT-29 cells were more sensitive to phenol treatments than Caco-2. In synthesis, the results of the present study represent a good starting point for understanding the potential apoptotic and antiproliferative effects of VOO phenolic compounds and their colonic metabolites.

The Health Benefiting Mechanisms of Virgin Olive Oil Phenolic Compounds.

Virgin olive oil (VOO) is credited as being one of the many healthful components associated with the Mediterranean diet. Mediterranean populations experience reduced incidence of chronic inflammatory disease states and VOO is readily consumed as part of an everyday Mediterranean dietary pattern. VOO is rich in phenolic compounds and the health promoting benefits of these phenolics are now established. Recent studies have highlighted the biological properties of VOO phenolic compounds elucidating their anti-inflammatory activities. This paper will review current knowledge on the anti-inflammatory and nutrigenomic, chemoprotective and anti-atherosclerotic activities of VOO phenolics. In addition the concentration, metabolism and bioavailability of specific phenolic compounds will be discussed. The evidence presented in the review concludes that oleurepein, hydroxytyrosol and oleocanthal have potent pharmacological activities in vitro and in vivo; however, intervention studies with biologically relevant concentrations of these phenolic compounds are required.

Towards green analysis of virgin olive oil phenolic compounds: Extraction by a natural deep eutectic solvent and direct spectrophotometric detection

The determination of phenolic compounds in extra virgin olive oils (EVOO) by means of rapid, low-cost, environment-free methods would be a desirable achievement. A natural deep eutectic solvent (DES) based on glucose and lactic acid was considered as extraction solvent for phenolic compounds in EVOO. DESs are green solvents characterized by high availability, biodegradability, safety, and low cost. The spectrophotometric characteristics of DES extracts of 65 EVOO samples were related to the total phenolic content of the oils, assessed by methanol-water extraction coupled to the Folin-Ciocalteu assay. A regression model (ncalibration=45, nvalidation=20), including the absorbance at two wavelengths (257, 324nm), was obtained, with an adjusted R2=0.762. Therefore the DES could provide a promising and viable approach for a green screening method of phenolic compounds in EVOO, by means of simple spectrophotometric measurements of extracts, even for on-field analysis (for example in olive mills).

Effect of virgin olive oil and thyme phenolic compounds on blood lipid profile: implications of human gut microbiota.

To investigate the effect of virgin olive oil phenolic compounds (PC) alone or in combination with thyme PC on blood lipid profile from hypercholesterolemic humans, and whether the changes generated are related with changes in gut microbiota populations and activities. A randomized, controlled, double-blind, crossover human trial (n=12) was carried out. Participants ingested 25mL/day for 3weeks, preceded by 2-week washout periods, three raw virgin olive oils differing in the concentration and origin of PC: (1) a virgin olive oil(OO) naturally containing 80mgPC/kg, (VOO), (2) a PC-enriched virgin olive oil containing 500mgPC/kg, from OO (FVOO), and (3) a PC-enriched virgin olive oil containing a mixture of 500mgPC/kg from OO and thyme, 1:1 (FVOOT). Blood lipid values and faecal quantitative changes in microbial populations, short chain fatty acids, cholesterol microbial metabolites, bile acids, and phenolic metabolites were analysed. FVOOT decreased seric ox-LDL concentrations compared with pre-FVOOT, and increased numbers of bifidobacteria and the levels of the phenolic metabolite protocatechuic acid compared to VOO (P<0.05). FVOO did not lead to changes in blood lipid profile nor quantitative changes in the microbial populations analysed, but increased the coprostanone compared to FVOOT (P<0.05), and the levels of the faecal hydroxytyrosol and dihydroxyphenylacetic acids, compared with pre-intervention values and to VOO, respectively (P<0.05). The ingestion of a PC-enriched virgin olive oil, containing a mixture of olive oil and thyme PC for 3weeks, decreases blood ox-LDL in hypercholesterolemic humans. This cardio-protective effect could be mediated by the increases in populations of bifidobacteria together with increases in PC microbial metabolites with antioxidant activities.

Temporal changes of virgin olive oil volatile compounds in a model system simulating domestic consumption: The role of biophenols

Virgin olive oil (VOO) aroma is one of the main quality attributes, to be maintained and preserved from the production to the use. We investigated the changes in VOO volatile compounds in a model system, made by refined olive oil spiked with selected VOO volatile molecules representative of its aroma, and the effect of VOO phenolic compounds addition upon storage to simulate the home consumption. Storage up to 7days was carried out under conditions simulating the home-use/storage of the oil, at 10°C in darkness, by sampling periodically an aliquot of oil by opening the bottle. SPME–GC/MS was used to quantify headspace concentration of 12 target volatile compounds. Storage resulted in a general lowering of most of the key aroma compounds. The presence of phenolic compounds resulted in a lower loss (17–44%) of aroma compounds with respect to the system without phenolics, whereas the strength of the effect depended upon the chemical classes and specific volatile compounds considered. Our results showed how the volatiles changes in 1week of use and that biophenols reduce the loss of positive odor notes of VOO also during home/restaurant consumption and storage once the bottle is opened.

Extraction, Separation, and Identification of Phenolic Compounds in Virgin Olive Oil by HPLC-DAD and HPLC-MS

The aim of this study was to evaluate the recovery of individual phenolic compounds extracted from virgin olive oil (VOO), from different Greek olive varieties. Sufficient recoveries (90%) of all individual phenolic compounds were obtained using methanol as an extraction solvent, acetonitrile for residue solubilization, and two washing steps with hexane. Moreover, in order to elucidate structural characteristics of phenolic compounds in VOO, high performance liquid chromatography with a diode array detector (HPLC-DAD) at 280 and 340 nm and HPLC coupled to electrospray ionization mass spectrometry (HPLC-ESI-MS) in the negative-ion mode were performed. The most abundant phenolic compounds were oleuropein derivatives with m/z 319 and 377 and ligstroside derivatives with m/z 303, 361. Lignans, such as 1-acetoxypinoresinol and pinoresinol were also present in substantial quantities in the phenolic fraction. However, pinoresinol was co-eluted with dialdehydic form of ligstroside aglycone (DAFLA) and it was not possible to be quantified separately. The phenolic extracts, obtained from different VOO samples, yielded similar HPLC profiles. Differences, however, were observed in the last part of the chromatogram, corresponding to isomers of the aldehydic form of ligstroside aglycone. Oxidized phenolic products, originating from secoiridoids, were also detected.

Stability of Virgin Olive Oil Phenolic Compounds during Long-Term Storage (18 Months) at Temperatures of 5-50 °C.

Virgin olive oil (VOO) phenolic compounds have high nutritional and biological properties. The purpose of this research was to study the stability of VOO phenolic compounds during long-term storage (18 months) at different temperatures (5, 15, 25, and 50 °C) and to verify the advantage of storing VOO at a temperature lower than the usual commercial conditions (20-25 °C). Four monovarietal VOOs that differed in their fatty acid profile and content of natural antioxidants were used in this study. The degradation of secoiridoid phenolics during storage displayed pseudo-first-order kinetics and depended on the initial content of phenolics related to olive oil variety. The initial degradation rate was similar at 5 and 15 °C but increased considerably at 25 °C and was even faster at 50 °C. Tyrosol derivatives were more stable than hydroxytyrosol compounds, especially in closed bottles with limited oxygen availability. The increase in the content of simple phenolics, the decrease of their secoiridoid derivatives, or the ratio of simple to secoiridoid phenolics could be used as indices of the oxidative and hydrolytic degradation of VOO phenolics. The shelf life of the studied VOO was considerably extended at reduced storage temperature (15 vs 25 °C). Moreover, storage conditions affected VOO phenolic content and therefore the expiration date of the health claim that olive oil polyphenols contribute to the protection of blood lipids from oxidative stress.