Gianfrancesco Montedoro

Antioxidant activity of tocopherols and phenolic compounds of virgin olive oil

The antioxidant effects of hydrophilic phenols and tocopherols on the oxidative stability in virgin olive oils and in purified olive oil have been evaluated. Total hydrophilic phenols and the oleosidic forms of 3,4-dihydroxyphenolethanol (3,4-DHPEA) were correlated (r=0.97) with the oxidative stability of virgin olive oil. On the contrary, tocopherols showed low correlation (r=0.05). Purified olive oil with the dialdehydic form of elenolic acid linked to 3,4-DHPEA, an isomer of oleuropeine aglycon, and 3,4-DHPEA had good oxidative stability. A synergistic effect was observed in the mixture of 3,4-DHPEA and its oleosidic forms with α-tocopherol in purified olive oil by the Rancimat method at 120°C.

Contribution of phenolic compounds to virgin olive oil quality

Hydrophilic phenols are the most abundant natural antioxidants of virgin olive oil (VOO), in which, however, tocopherols and carotens are also present. The prevalent classes of hydrophilic phenols found in VOO are phenolic alcohols, phenolic acids, flavonoids, lignans and secoiridoids. Secoiridoids including aglycon derivatives of oleuropein, demethyloleuropein and ligstroside, that are present in olive fruit, are the most abundant phenolic antioxidants of VOO. In this paper, the phenolic composition of VOO as well as the agronomic and technological parameters that affect their concentration in the oil are discussed. The olive cultivar and the ripening stage of fruit, in fact, have always been the most studied agronomic aspects that affect phenolic concentration in VOO. However, the malaxation conditions and the extraction systems used to separate oil from olive pastes (i.e. pressure three-phases and two-phases centrifugation systems) are also of great importance.

Phenolic compounds in olive oil: antioxidant, health and organoleptic activities according to their chemical structure

Abstract.Hydrophilic phenols are the most abundant natural antioxidants of virgin olive oil (VOO), in which, however, tocopherols and carotenes are also present. The prevalent classes of hydrophilic phenols found in VOO are phenolic alcohols and acids, flavonoids, lignans and secoiridoids. Among these substances the last two classes include the most concentrate phenols of VOO. Secoiridoids, like aglycone derivatives of oleuropein, demethyloleuropein and ligstroside, are present in olive fruit as most abundant VOO phenolic antioxidants. Several important biological properties (antioxidant, anti-inflammatory, chemopreventive and anti-cancer) and the characteristic pungent and bitter tasty properties have been attributed to VOO phenols. Relationships between polyphenols activities and their chemical structures are discussed in this paper.

Potential anti-cancer effects of virgin olive oil phenols on colorectal carcinogenesis models in vitro

The traditional Mediterranean diet is thought to represent a healthy lifestyle; especially given the incidence of several cancers including colorectal cancer is lower in Mediterranean countries compared to Northern Europe. Olive oil, a central component of the Mediterranean diet, is believed to beneficially affect numerous biological processes. We used phenols extracted from virgin olive oil on a series of in vitro systems that model important stages of colon carcinogenesis. The effect the extract on DNA damage induced by hydrogen peroxide was measured in HT29 cells using single cell microgel‐electrophoresis. A significant anti‐genotoxic linear trend (p = 0.011) was observed when HT29 cells were pre‐incubated with olive oil phenols (0, 5, 10, 25, 50, 75, 100 μg/ml) for 24 hr, then challenged with hydrogen peroxide. The olive oil phenols (50, 100 μg/ml) significantly (p = 0.004, p = 0.002) improved barrier function of CACO2 cells after 48 hr as measured by trans‐epithelial resistance. Significant inhibition of HT115 invasion (p < 0.01) was observed at olive oil phenols concentrations of 25, 50, 75, 100 μg/ml using the matrigel invasion assay. No effect was observed on HT115 viability over the concentration range 0, 25, 50 75, 100 μg/ml after 24 hr, although 75 and 100 μg/ml olive oil phenols significantly inhibited HT115 cell attachment (p = 0.011, p = 0.006). Olive oil phenols had no significant effect on metastasis‐related gene expression in HT115 cells. We have demonstrated that phenols extracted from virgin olive oil are capable of inhibiting several stages in colon carcinogenesis in vitro.

Inhibitory effects of olive oil phenolics on invasion in human colon adenocarcinoma cells in vitro

Studies in human, animal and cellular systems suggest that phenols from virgin olive oil are capable of inhibiting several stages in carcinogenesis, including metastasis. The invasion cascade comprises cell attachment to extracellular matrix components or basement membrane, degradation of basement membrane by proteolytic enzymes and migration of cells through the modified matrix. In the present study, we investigated the effect of phenolics extracted from virgin olive oil (OVP) and its main constituents: hydroxytyrosol (3,4‐dihydroxyphenylethanol), tyrosol (p‐hydroxyphenylethanol), pinoresinol and caffeic acid. The effects of these phenolics were tested on the invasion of HT115 human colon carcinoma cells in a Matrigel invasion assay. OVP and its compounds showed different dose‐related anti‐invasive effects. At 25 μg/ml OVP and equivalent doses of individual compounds, significant anti‐invasive effects were seen in the range of 45–55% of control. Importantly, OVP, but not the isolated phenolics, significantly reduced total cell number in the Matrigel invasion assay. There were no significant effects shown on cell viability, indicating the reduction of cell number in the Matrigel invasion assay was not due to cytotoxicity. There were also no significant effects on cell attachment to plastic substrate, indicating the importance of extracellular matrix in modulating the anti‐invasive effects of OVP. In conclusion, the results from this study indicate that phenols from virgin olive oil have the ability to inhibit invasion of colon cancer cells and the effects may be mediated at different levels of the invasion cascade.

Influence of the Decrease in Oxygen during Malaxation of Olive Paste on the Composition of Volatiles and Phenolic Compounds in Virgin Olive Oil

The sensory and health properties of virgin olive oil (VOO) are highly related to its volatile and phenolic composition. Oxygen control in the pastes during malaxation may be a new technological parameter to regulate enzymatic activities, such as polyphenoloxidase, peroxidase, and lipoxygenase, which affect the phenolic and volatile composition of VOO. In this work, we monitored CO2 and O2 concentrations during industrial-scale olive paste malaxation with various initial O2 concentrations within the malaxer headspace. Results show that the O2 concentration in the malaxer headspace did not affect CO2 production during processing, whereas a strong influence was observed on the changes of the phenolic composition of olive pastes and VOOs, with high correlation coefficient for the total phenols (R = 0.94), especially for oleuropein and demethyloleuropein derivatives (R = 0.81). In contrast, aroma production during malaxation was minimally affected by the O2 concentration in the malaxer headspace.

Relationships between the volatile compounds evaluated by solid phase microextraction and the thermal treatment of tomato juice : optimization of the blanching parameters

Abstract Tomato juice contains volatile compounds that are originally detected in fruit, such as terpenes, and others that are originated during processing by lipoxygenase activity, carotenoid co-oxidation and Maillard reaction that can be activated during the thermal treatments. This paper reports the analysis of the volatile compounds of tomato juice sampled by solid phase microextraction (SPME) and the optimization of the blanching parameters in tomato juice, using the volatile compounds as markers. One hundred and ninety volatile compounds, including ketones, aldehydes, alcohols, esters, ethers, hydrocarbons, sulfur, nitrogen and oxygen compounds, phenols, oxygen-containing heterocyclic compounds, free acids and lactones, were identified or tentatively identified by the GC–MS technique. The thermal treatment mainly modifies saturated and unsaturated C6 alcohols and aldehydes, esters, ketones and carotenoid derivatives. The optimal conditions for the blanching, selected by response surface modelling (RSM), were 67°C for 24 min and 86°C for 3.5 min for the cold break and the hot break treatments, respectively.

Effect of thermal treatment in the headspace volatile compounds of tomato juice

Volatile compounds of tomato juice include compounds of the original fruit, such as terpenes, and other substances that are originated during processing by lipoxygenase activity, carotenoid cooxidation and Maillard reaction. This paper reports: a) a comparison between solid phase microextraction (SPME) and traditional static (SHSA) and dynamic headspace (DHSA); b) optimization of SPME; c) evaluation of the volatile compounds of tomato juice under different conditions of thermal treatment. Results were analyzed by multivariate statistical analysis. One hundred ninety and 219 volatile compounds were sampled using SPME and traditional SHSA and DHSA, respectively; these compounds belonged to the following chemical classes: ketones, aldehydes, alcohols, esters, ethers, hydrocarbons, sulfur, nitrogen and oxygen compounds, phenols, oxygen-containing heterocyclic compounds, free acids and lactones. The thermal treatment mainly modified saturated and unsaturated C6 alcohols and aldehydes, terpene and carotenoid derivatives.

Antagonism between olive oil phenolics and nitric oxide on lymphomonocyte cytosolic calcium

Some biological actions of olive oil phenolics (inhibition of platelet aggregation, decrease of LDL-oxidation, inhibition of bacterial growth and hypertensive action) have been attributed to NOS stimulation in endothelial cells through an increase of cytosolic calcium, notwithstanding the scavenging activity of phenolics on NO and superoxide. In this paper, we determine the concentration of cytosolic calcium in human lymphomonocytes incubated with high concentrations of NO-donors (CysNO) and we evaluate the effects of olive oil phenolics on this parameter. CysNO induces a marked decrease of cytosolic calcium; both olive oil phenolics oppose this action of CysNO. The effects of phenolics and CysNO are independent and additive. (Mol Cell Biochem xxx: 181–184, 2005)