1-Phenyl-6,7-dihydroxy-isochroman suppresses lipopolysaccharide-induced pro-inflammatory mediator production in human monocytes.

Extra-virgin olive oil is an integral ingredient of the Mediterranean diet, and it has been suggested that its high consumption has beneficial effects on human health. Its protective effect, in particular against the development of CVD, has been related not only to the high content of oleic acid, but also to the antioxidant and anti-inflammatory properties of polyphenols. In order to verify the anti-inflammatory and anti-atherogenic properties of hydroxy-isochromans, a class of ortho-diphenols present in extra-virgin olive oil, we investigated the potential ability of 1-phenyl-6,7-dihydroxy-isochroman (L137) to modulate the production of key inflammatory mediators by human monocytes, by evaluating its in vitro effects on prostanoid (thromboxane A(2) and PGE(2)) and cytokine (TNF-α) production. Its effect on the protein expression of the inducible form of cyclo-oxygenase-2 (COX-2), a pro-inflammatory enzyme responsible for elevated prostanoid levels, was also explored. The results showed that L137 significantly inhibited both prostanoid and TNF-α production in lipopolysaccharide-primed human monocytes in a dose-dependent manner, by inhibiting the COX activity of COX-2. We also demonstrated that the effects of the isochroman are mediated, at least partly, through the suppression of NF-κB activation leading to the down-regulation of the synthesis of COX-2.

Olive oil isochromans inhibit human platelet reactivity.

The effects of certain polyphenolic compounds in red wine, such as resveratrol and quercetin, have been widely investigated to determine the relationship between dietary phenolic compounds and the decreased risk of cardiovascular diseases. However, the effects of polyphenolic compounds contained in other foods, such as olive oil, have received less attention and little information exists regarding the biological activities of the phenol fraction in olive oil. The aim of this study was to evaluate the antiplatelet activity and antioxidant power of two isochromans [1-(3'-methoxy-4'-hydroxy-phenyl)-6,7-dihydroxy-isochroman (encoded L116) and 1-phenyl-6,7-dihydroxy-isochroman (encoded L137)] recently discovered in olive oil and synthesized in our laboratory from hydroxytyrosol. These compounds were effective free radical scavengers and inhibited platelet aggregation and thromboxane release evoked by agonists that induce reactive oxygen species-mediated platelet activation including sodium arachidonate and collagen, but not ADP. Release of tritiated arachidonic acid from platelets was also impaired by L116 and L137. These results indicate that other Mediterranean diet nutraceuticals also exhibit antioxidant activity that could be beneficial in the prevention of vascular diseases.