Serena Viappiani

Olive Phenol Hydroxytyrosol Prevents Passive Smoking–Induced Oxidative Stress

BackgroundOxidative stress is involved in the onset of several degenerative disorders, and epidemiological studies indicate that a high intake of dietary antioxidants, as in the case of the Mediterranean basin, is protective. Olive mill waste waters (OMWWs) are a byproduct of olive oil production rich in phenolic antioxidants, such as hydroxytyrosol. We tested the effects of a low dose of an OMWW extract in a model of sidestream smoke–induced oxidative stress in rats by evaluating the urinary excretion of 8-iso-prostaglandin (PG) F2&agr; (iPF2&agr;-III). Methods and ResultsAn OMWW extract (5 mg/kg, providing 414 &mgr;g/kg of hydroxytyrosol) was administered to rats daily for 4 days, during which time the animals were exposed to sidestream smoke for 20 minutes once a day. Daily urines were collected, and the urinary excretion of 8-iso-PGF2&agr; was evaluated as an index of oxidative stress–induced in vivo lipid peroxidation. The exposure of rats to passive smoking increased the urinary excretion of 8-iso-PGF2&agr; by 44±4.2% at 48 hours and by 55±10% at 96 hours. Treatment with the OMWW extract was able to completely prevent the increase at 48 hours and resulted in lower increments (34±18% versus 55±10%) of 8-iso-PGF2&agr; excretion at 96 hours. ConclusionsA low dose of hydroxytyrosol, administered through OMWW, reduces the consequences of sidestream smoke–induced oxidative stress in rats.

The Cycloxygenase-2 inhibitor SC58236 is neuroprotective in an in vivo model of focal ischemia in the rat.

Focal ischemia was induced in the fronto-parietal region of rat brain, by injection of Rose Bengal, followed by light activation. Focal ischemia was accompanied by formation of PGD(2) peaking 60-90 min post irradiation and declining thereafter. Increased Cycloxygenase-2 (COX-2) expression was also observed. Control ischemic rats showed distinct morphological alterations with necrosis of neurons, glial cells and blood vessels, surrounded by a halo with pyknotic cells with cytoplasm swelling and vacuolization. Compound SC58236, a selective COX-2 inhibitor, dose-dependently prevented, ischemia-induced eicosanoid formation (area under the curve (AUC) of controls: 3.11 +/- 0.87; AUC of 20 mg/kg SC58236: 0.39 +/- 0.24), and caused significant reduction of damaged area (30.7 and 18.9% at SC58236 20 and 6.6 mg/kg), suggesting that selective inhibitors of COX-2 are neuroprotective.

Cysteinyl-leukotrienes receptor activation in brain inflammatory reactions and cerebral edema formation: a role for transcellular biosynthesis of cysteinyl-leukotrienes

We studied the effect of intravascular activation of human neutrophils on the synthesis of cysteinyl leukotrienes (cysLT) and the formation of cerebral edema in guinea‐pig brains. Challenge with the chemotactic formylated tripeptide fMLP (0.1 µM) of neutrophil‐perfused brain in vitro resulted in blood‐brain barrier disruption associated with a significant increase of cysLT. Both events were completely prevented by neutrophil pretreatment with a specific 5‐lipoxygenase (5‐LO) inhibitor. Perfusion with the 5‐LO metabolite leukotriene B4 (10 nM), together with neutrophils treated with the 5‐LO inhibitor, did not restore the alteration in permeability observed upon perfusion with untreated and activated neutrophils. The dual cysLT1‐cysLT2 receptor antagonist BAYu9773 was more potent and more effective than a selective cysLT1 antagonist in preventing the brain permeability alteration induced by neutrophil activation. RT‐PCR showed significant expression of cysLT2 receptor mRNA in human umbilical vein endothelial cells. Intravital microscopy in mice showed that inhibition of leukotriene synthesis significantly reduced firm adhesion of neutrophils to cerebral vessels without affecting rolling. These data support the hypothesis that neutrophil and endothelial cells cooperate toward the local synthesis of cysLT within the brain vasculature and, acting via the cysLT2 receptor on endothelial cells, may represent a contributing pathogenic mechanism in the development of cerebral inflammation and edema.

Cyclooxygenase-inhibiting nitric oxide donators for osteoarthritis.

Nonsteroidal anti-inflammatory drugs (NSAIDs) remain the most commonly used medications for the treatment of the symptoms of many chronic inflammatory diseases, including osteoarthritis. Unfortunately, the toxicity of NSAIDs substantially limits their long-term use. Some newer NSAIDs, namely selective cyclooxygenase (COX)-2 inhibitors, exhibit greater gastrointestinal safety, and concomitant use of anti-secretory drugs can also reduce NSAID-induced gastropathy. However, NSAIDs also adversely affect the cardiovascular system. A new class of anti-inflammatory drugs, COX-inhibiting nitric oxide donators (CINODs), has been designed to exert similar anti-inflammatory effects as NSAIDs, but with an improved safety profile. CINODs release nitric oxide, providing protective effects in the gastrointestinal tract and attenuating the detrimental effects on blood pressure normally associated with NSAIDs. We provide an outline of the rationale for CINODs and their activity, in addition to an overview of the pre-clinical and clinical profile of the most advanced CINOD, naproxcinod.

Prevention of Bleomycin-Induced Lung Fibrosis in Mice by a Novel Approach of Parallel Inhibition of Cyclooxygenase and Nitric-Oxide Donation Using NCX 466, a Prototype Cyclooxygenase Inhibitor and Nitric-Oxide Donor

Cyclooxygenase (COX)-inhibiting nitric oxide (NO) donors (CINODs) are designed to inhibit COX-1 and COX-2 while releasing NO. COX inhibition is responsible for anti-inflammatory and pain-relieving effects, whereas NO donation can improve microcirculation and exert anti-inflammatory and antioxidant actions. In an in vivo mouse model of bleomycin-induced lung fibrosis, we evaluated whether a prototype CINOD compound, (S)-(5S)-5,6-bis(nitrooxy)hexyl)2-(6-methoxynaphthalen-2-yl)propanoate (NCX 466), may show an advantage over naproxen, its congener drug not releasing NO. Bleomycin (0.05 IU) was instilled intratracheally to C57BL/6 mice, which were then treated orally with vehicle, NCX 466 (1.9 or 19 mg/kg), or an equimolar dose of naproxen (1 or 10 mg/kg) once daily for 14 days. Afterward, airway resistance, assumed as lung stiffness index, was assayed, and lung specimens were collected for analysis of lung inflammation and fibrosis. NCX 466 and naproxen dose-dependently prevented bleomycin-induced airway stiffness and collagen accumulation. NCX 466, at the highest dose, was significantly more effective than naproxen in reducing the levels of the profibrotic cytokine transforming growth factor-β and the oxidative stress markers thiobarbituric acid reactive substance and 8-hydroxy-2′-deoxyguanosine. NCX 466 also decreased myeloperoxidase activity, a leukocyte recruitment index, to a greater extent than naproxen. A similar inhibition of prostaglandin E2 was achieved by both compounds. In conclusion, NCX 466 has shown a significantly higher efficacy than naproxen in reducing lung inflammation and preventing collagen accumulation. These findings suggest that COX inhibition along with NO donation may possess a therapeutic potential in lung inflammatory diseases with fibrotic outcome.

Leukotriene modifiers: novel therapeutic opportunities in asthma

Cysteinyl leukotrienes (Cys-LT) are powerful proinflammatory autacoids that cause long-lasting bronchoconstriction, plasma leakage, increased mucus production; their biological activity suggests a prominent role in the etiopathology of asthma and several Cys-LT receptor antagonists and synthetase inhibitors have been developed as new antiasthmatic drugs. Zafirlukast was discovered by a mechanism-based approach to drug discovery; early structure-activity relationship analyses of the prototype SRS-A antagonist FPL-55712, lead to the identification of an indole-containing lead compound that was more specific than FPL-55712. Modifications were made on the lipid-like tail, indole backbone and acidic head region of this lead compound, resulting in potent and selective leukotriene receptor antagonists such as ICI-198615 and 204219 (zafirlukast). On the basis of successful results in preclinical asthma models, zafirlukast was recommended for clinical development and became the first leukotriene-modifier to be approved for the treatment of asthma. Leukotriene biosynthesis inhibitors (LSI) also represent a promising approach to the treatment of asthma and may theoretically provide a broader protection than Cys-LT receptor antagonists by inhibition of the synthesis of the two major leukotrienes, the Cys-LT and the chemotactic LTB4. The LSI BAY X-1005 is the result of a broad chemistry program that identified 15-HETE as an endogenous inhibitor of leukotriene synthesis and REV 5901 as a lead prototypic quinoline-based 5-lipoxygenase (5-LO) inhibitor. Clinical studies demonstrated the effectiveness of BAY X-1005 in experimental conditions such as allergen provocation and cold-air induced asthma. However, no consistent treatment effect in the overall asthma population (mild to moderately severe asthmatics) lead to discontinuation of its development.

Clinical pharmacology of non-steroidal anti-inflammatory drugs: novel acquisitions

Prostaglandins (PGs), thromboxanes (TXs), leukotrienes (LTs), and hydroxyeicosatetraenoic acids (HETEs) are collectively referred to as eicosanoids because they are derived from 20-carbon essential fatty acids that contain three, four or five double bonds (i.e. 8, 11, 14-eicosatrienoic acid, 5, 8, 11, 14-eicosatetraenoic acid or arachidonic acid and 5, 8, 11, 14, 17-eicosapentaenoic acid). In humans, arachidonic acid represents the most abundant percursor.

Evaluation of the Pharmacological Activity of the Pure Cysteinyl-Leukotriene Receptor Antagonists CGP 45715A (Iralukast) and CGP 57698 in Human Airways

Cysteinyl-containing leukotrienes (cysteinyl-LTs) produce bronchoconstriction, mucus hypersecretion, and pro-inflammatory effects (Dahlen et al., 1980; Dahlen et al., 1981; Foster C von Sprecher et al., 1991; von Sprecher et al., 1996).