[EN] Objectives. We evaluated the antioxidant effects of the specific phenolic compounds of virgin olive oil and their ability to modify the release of eicosanoids, pro-inflammatory mediators, in leukocytes. Results. All four phenolics inhibited leukotriene B4 generation at the 5-lipoxygenase level with effectiveness hydroxytyrosol > oleuropein > caffeic acid > tyrosol (approximate IC50 values: 15 µM, 80 µM, 200 µM and 500 µM, respectively). In contrast, none of these compounds caused substantial inhibition of thromboxane generation via the cyclo-oxygenase pathway. None of these compounds were toxic to leukocytes at the concentrations tested. Regarding the antioxidant and oxygen free radical scavenging properties, hydroxytyrosol, caffeic acid, oleuropein and tyrosol (decreasing order of effectiveness) quenched the chemiluminescence signal due to reactive oxygen species generated by tetradecanoylphorbolacetate-stimulated rat leukocytes, resulting in a 70% to 37% inhibition at 320 µM. In a cell free system the phenolics exerted potent scavenging effects of hydrogen peroxide and superoxide anion. Moreover, they prevented Fe3+-ascorbate-induced lipid peroxidation in a dose-related manner. The phenolics also scavenged nitrogen free radicals, as nitric oxide and peroxynitrite. Tyrosol, with only one hydroxyl moiety, was the less effective compound in the different assays. Conclusions. We demonstrate that phenolics found in virgin olive oil possess an interesting array of lipoxygenase-inhibitory and antioxidant properties that might be related to the beneficial heath effects described for usual virgin olive oil consumers.

Peer reviewed