1-Phenil-6,7-dihydroxy-isochroman inhibits inflammatory activation of microglia.

Inflammation plays a central role in the pathogenesis of several brain disorders and neuronal injury, and it develops as a consequence of glial cell activation. Activated microglial cells generate potentially damaging nitric oxide, oxygen free radicals, prostanoids, and pro-inflammatory cytokines. Naturally occurring polyphenols have recently received attention for their potential protective effect on neurodegenerative disorders characterized by microglial activation, due to their anti-inflammatory and antioxidant properties. In the present study, we investigated, using an in vitro model of primary microglia, the ability of 1-phenyl-6,7-dihydroxy-isochroman (encoded L 137), a natural polyphenolic compound, to inhibit microglia activation induced by an inflammatory insult. So, L137 effects (1-100 µM) on production of pro-inflammatory mediators in lipopolysaccharide (LPS)-activated microglial cells were evaluated. The expression of inducible isoforms of nitric oxide synthase (iNOS) and cyclooxygenase (COX-2) as well as of the nuclear transcription Factor-kappa B (NF-κB) was also performed in cellular lysates by Immunoblot. L137 significantly reduced tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-6 secretion, as well as nitric oxide (NO) and prostanoids [Thromboxane (TX)B2, prostaglandin (PG)E2] production in activated microglial cells. Western blot analyses showed an inhibitory effect of L137 on the iNOS and COX-2 expression, mediated by a modulation of redox-sensitive nuclear transcriptional factor (NF)-κB, known to control a wide array of genes involved in inflammation. In conclusion, this study demonstrate that L137 is able to inhibit the production of pro-inflammatory and neurotoxic mediators by LPS-activated microglial cells thus suggesting L137 as a potential lead compound for drug development for neurodegenerative disorders where microglia-mediated inflammatory responses play an important pathogenic role.

Highly electroconductive multiwalled carbon nanotubes as potentially useful tools for modulating calcium balancing in biological environments.

Aiming to explore the mechanisms modulating cell-carbon nanotube interactions, we investigated whether Ca(2+) ion balancing between intra- and extracellular environments could be affected by multiwalled carbon nanotubes (MWCNTs). We analyzed the effects induced by two different kinds of MWCNTs (as prepared and annealed at 2400°C) on the intracellular Ca(2+) ion levels in rat electrically sensitive cells and on the intercellular junction integrity of rat adenocarcinoma colon cells and platelet aggregation ability, which depend on the Ca(2+) concentration in the medium. MWCNTs, purified by annealing and more electroconductive as compared to nonannealed MWCNTs, affected Ca(2+) ion balancing between extra- and intracellular environments and induced changes on Ca(2+) ion-dependent cellular junctions and platelet aggregation, behaving as the calcium chelator ethylene glycol tetraacetic acid. This could be due to the sorption of cationic Ca(2+) ions on CNTs surface because of the excess of negatively charged electrons on the aromatic units formed on MWCNTs after annealing. From the ClinicAL Editor: The authors investigated whether Ca(2+) ion balance between intra- and extracellular space can be modulated by multiwalled carbon nanotubes (MWCNTs). Annealed nanotubes induced changes on Ca(2+) dependent cellular junctions and platelet aggregation, behaving similary to ethylene glycol tetraacetic acid, an established calcium chelator.

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.

Cigarette smoke inhibits adenine nucleotide hydrolysis by human platelets.

Cigarette smoking is a recognized risk factor for cardiovascular diseases and has been implicated in the pathogenesis of atherosclerosis and thrombotic events. In athero-thrombotic diseases, the extracellular adenine nucleotides play an important role by triggering a range of effects such as the recruitment and activation of platelets, endothelial cell activation and vasoconstriction. NTPDase, a plasma membrane-bound enzyme, is the most relevant enzyme involved in the hydrolysis of extracellular tri- and di-phosphate nucleotides to adenosine monophosphate, which is further degraded by 5'ectonucleotidase to the anti-thrombotic and anti-inflammatory mediator adenosine. Thus, the preserved activity of these enzymes, regulating the extracellular concentrations of nucleotides, is critical in thromboregulatory functions. In the present in vitro study, performed on human platelets suspended in undiluted or diluted aqueous cigarette smoke extract (aCSE), we demonstrated that undiluted and 1 : 2 diluted aCSE is able to significantly reduce ADP hydrolysis (-24% and 12%, respectively) by intact human platelets. ATP degradation was also reduced (-31%) by undiluted aCSE. Conversely, aCSE did not alter platelet AMP hydrolysis. Results obtained by using N-acetylcysteine, a thiol-containing antioxidant, suggest that stable oxidants present in aCSE are responsible for the platelet NTPDase inhibition induced by aCSE. The decreased adenine nucleotide degradation could play a significant role in the extensive platelet activation and vascular inflammation observed in chronic smokers.

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.