[show abstract][hide abstract] ABSTRACT: Hydrogen sulfide (H2S) is an endogenous gasotransmitter, which mediates important physiological effects in the cardiovascular system. Accordingly, an impaired production of endogenous H2S contributes to the pathogenesis of important cardiovascular disorders, such as hypertension. Therefore, exogenous compounds, acting as H2S-releasing agents, are viewed as promising pharmacotherapeutic agents for cardiovascular diseases. Thus, this paper aimed at evaluating the H2S-releasing properties of some aryl isothiocyanate derivatives and their vascular effects. The release of H2S was determined by amperometry, spectrophotometry and gas/mass chromatography. Moreover, the vascular activity of selected isothiocyanates were tested in rat conductance (aorta) and coronary arteries. Since H2S has been recently reported to act as an activator of vascular Kv7 potassium channels, the possible membrane hyperpolarizing effects of isothiocyanates were tested on human vascular smooth muscle (VSM) cells by spectrofluorescent dyes. Among the tested compounds, phenyl isothiocyanate (PhNCS) and 4-carboxyphenyl isothiocyanate (PhNCS-COOH) exhibited slow-H2S-release, triggered by organic thiols such as L-Cysteine. These compounds were endowed of vasorelaxing effects on conductance and coronary arteries. Moreover, these two isothiocyanates caused membrane hyperpolarization of VSM cells. The vascular effects of isothiocyanates were strongly abolished by the selective Kv7-blocker XE991. In conclusion, the isothiocyanate function can be viewed as a suitable slow H2S-releasing moiety, endowed with vasorelaxing and hypotensive effects, typical of this gasotransmitter. Thus, such a chemical moiety can be employed for the development of novel chemical tools for basic studies and promising cardiovascular drugs.
[show abstract][hide abstract] ABSTRACT: This study was aimed at investigating the antitumor activity of novel 2-oxindole derivatives against a well-characterized human nonsmall cell lung cancer (NSCLC) cell line. Test compounds produced an antiproliferative activity in the low micromolar/submicromolar range of concentrations and significantly induced typical apoptotic morphology with cell shrinkage, nuclear condensation and fragmentation, and rupture of cells into debris in a relatively low percentage of A549 cells. Cell cycle arrest occurred at the G1/S phase (1a and 2), and Akt phosphorylation was significantly inhibited at Thr308 and Ser473. The most active compound (1a) has an IC50 6-fold lower than the Akt inhibitor, perifosine. These data suggest that the new compounds may be cytostatic and may have maximum clinical effects in NSCLC patients who do not respond to EGFR inhibitors. These findings prompt us to further explore the oxindole structure as leading scaffold to design new molecules with potent antitumor activity against NSCLC.
[show abstract][hide abstract] ABSTRACT: Selective cyclooxygenase 2 (COX2) inhibitors (COXIBs) are effective anti-inflammatory and analgesic drugs with improved gastrointestinal (GI) safety compared to nonselective nonsteroidal anti-inflammatory drugs (known as traditional (tNSAIDs). However, their use is associated with a cardiovascular (CV) hazard (i.e. increased incidence of thrombotic events and hypertension) due to the inhibition of COX2-dependent vascular prostacyclin. Aiming to design COX2-selective inhibitors with improved CV safety, new NO-releasing COXIBs (NO-COXIBs) have been developed. In these hybrid drugs, the NO-mediated CV effects are expected to compensate for the COXIB-mediated inhibition of prostacyclin. This study evaluates the potential CV beneficial effects of VA694, a promising NO-COXIB, the anti-inflammatory effects of which have been previously characterized in several in vitro and in vivo experimental models. When incubated in hepatic homogenate, VA694 acted as a slow NO-donor. Moreover, it caused NO-mediated relaxant effects in the vascular smooth muscle. The chronic oral administration of VA694 to young spontaneously hypertensive rats (SHRs) significantly slowed down the age-related development of hypertension and was associated with increased plasma levels of nitrates, stable end-metabolites of NO. Furthermore, a significant improvement of coronary flow and a significant reduction of endothelial dysfunction were observed in SHRs submitted to chronic administration of VA694. In conclusion, VA694 is a promising COX2-inhibiting hybrid drug, showing NO releasing properties which may mitigate the CV deleterious effects associated with the COX2-inhibition.
Pharmacological Research 09/2013; · 4.35 Impact Factor
[show abstract][hide abstract] ABSTRACT: Microparticles (MPs) are membrane fragments that may play a role in the pathogenesis of chronic respiratory diseases. We aimed to investigate whether human monocytes/macrophage-derived MPs could induce a pro-inflammatory phenotype in human bronchial smooth muscle cells (BSMC) and the effect of montelukast in this setting. Experimental methods included isolation of human monocytes/macrophages and generation of monocyte-derived MPs, RT-PCR analysis of gene expression, immunoenzymatic determination of pro-inflammatory factor release, bioluminescent assay of intracellular cAMP levels and electromobility shift assay analysis of NF-κB nuclear translocation. Stimulation of human BSMC with monocyte-derived MPs induced a pro-inflammatory switch in human BSMC by inducing gene expression (COX-2 and IL-8), protein release in the supernatant (PGE2 and IL-8), and heterologous β2-adrenoceptor desensitisation. The latter effect was most likely related to autocrine PGE2 since pre-treatment with COX inhibitors restored the ability of salbutamol to induce cAMP synthesis in desensitised cells. Challenge with MPs induced nuclear translocation of NF-κB and selective NF-κB inhibition decreased MP-induced cytokine release in the supernatant. Montelukast treatment prevented IL-8 release and heterologous β2-adrenoceptor desensitisation in human BSMC exposed to monocyte-derived MPs by blocking NF-κB nuclear translocation. These findings provide evidence on the role of human monocyte-derived MPs in the airway smooth muscle phenotype switch as a novel potential mechanism in the progression of chronic respiratory diseases and on the protective effects by montelukast in this setting.
Pharmacological Research 08/2013; · 4.35 Impact Factor
[show abstract][hide abstract] ABSTRACT: Naringenin (NAR), flavonoid abundant in the genus Citrus, has been reported to interact with the large-conductance calcium-activated potassium channels (BK). Since activators of BK channels expressed in cardiac mitochondria trigger protective effects in several models of myocardial ischemia/reperfusion (I/R), this work aimed to evaluate the potential cardioprotective effects of NAR and the involvement of mitochondrial BK channels.In an in vivo model of acute infarct in rats, NAR (100 mg/kg i.p.) significantly reduced the heart injury induced by I/R. This effect was antagonized by the selective BK-blocker paxilline (PAX). The cardioprotective dose of NAR did not cause significant effects on the blood pressure. In Largendorff-perfused rat hearts submitted to ischemia/reperfusion, NAR improved the post-ischemic functional parameters (left ventricle developed pressure and dP/dt) with lower extension of myocardial injury. On isolated rat cardiac mitochondria, NAR caused a concentration-dependent depolarization of mitochondrial membrane and caused a trans-membrane flow of thallium (potassium-mimetic cation). Both these effects were antagonized by selective blockers of BK channels. Furthermore, NAR half-reduced the calcium accumulation into the matrix of cardiac mitochondria exposed to high calcium concentrations. In conclusion, NAR exerts anti-ischemic effects through a “pharmacological preconditioning” that it is likely to be mediated, at least in part, by the activation of mitochondrial BK channels.
[show abstract][hide abstract] ABSTRACT: Montelukast (MK) is a potent cysteinyl-leukotriene receptor antagonist that causes dose-related improvements in chronic asthma. We sought to determine whether MK was able to prevent salbutamol-induced tolerance in airway smooth muscle. Homologous β2-adrenoceptor desensitisation models were established in guinea-pigs and in human bronchial smooth muscle cells by chronic salbutamol administration. Characterisation tools included measurement of the response of tracheal smooth muscle tissues to salbutamol, analysis of gene expression and receptor trafficking, evaluation of intracellular cAMP levels and phosphodiesterase (PDE) activity in human bronchial smooth muscle cells. Salbutamol-induced β2-adrenoceptor desensitisation was characterised by β2-agonist hyporesponsiveness (-30%, p<0.001) in desensitised tracheal smooth muscle, as compared to controls. MK, given intraperitoneally at 5 mg/kg(/)day for 6 consecutive days, completely restored tissue responsiveness to salbutamol. Prolonged salbutamol treatment significantly decreased cAMP synthesis, induced a complete removal of the β2-adrenoceptor from plasma membrane with a parallel increase in the cytosol and increased PDE4D5 gene transcription and PDE activity in human bronchial smooth muscle cells. In homologously desensitised BSMC, MK 30 μM for 24 h was able to prevent salbutamol subsensitivity and such an effect was associated with inhibition of salbutamol-induced PDE4 activity and restoration of membrane β2-adrenoceptor expression and function. These findings suggest the presence of a favourable interaction between MK and β2-adrenoceptor agonists that might improve the therapeutic index of bronchodilators in patients with chronic respiratory diseases.
[show abstract][hide abstract] ABSTRACT: Flavonoids are important components of 'functional foods', with beneficial effects on the cardiovascular function, mainly due to their antioxidant activity. Many flavonoids exert antihypertensive, anti-atherosclerotic and antiplatelet activity and positive effects against endothelial dysfunction. Recent evidence indicates that they exert cardioprotective effects against myocardial ischaemia/reperfusion (I/R) injury. The aim of this work was to investigate these properties for flavonoids with different structural characteristics.
In this work, the cardioprotective effects of eight flavonoids endowed with different structural characteristics were tested on Langendorff-perfused rat hearts submitted to 30 min of global ischaemia followed by 120 min of reperfusion (I/R).
Only the 5-hydroxy-substituted derivatives, such as 5-hydroxy flavone, apigenin, chrysin and naringenin, conferred on the hearts an improved post-ischaemic functional recovery associated with lower extension of tissue injury. A similar pharmacological profile was exhibited by 5-methoxy flavone. In contrast, 6-hydroxy flavone, 7-hydroxy flavone and 4'-hydroxy flavanone did not confer significant protection against the injury induced by I/R.
Some flavonoids exhibit direct cardioprotective effects against the injury induced by drastic I/R and this pharmacological property seems to be related to their structural characteristics. Such an influence of structural requirements seems to indicate that the cardioprotective effects may be due to the interaction with specific pharmacological targets.
The Journal of pharmacy and pharmacology. 05/2013; 65(5):750-6.
[show abstract][hide abstract] ABSTRACT: Naringenin (NAR), flavonoid abundant in the genus Citrus, has been reported to interact with the large-conductance calcium-activated potassium channels (BK). Since activators of BK channels expressed in cardiac mitochondria trigger protective effects in several models of myocardial ischemia/reperfusion (I/R), this work aimed to evaluate the potential cardioprotective effects of NAR and the involvement of mitochondrial BK channels. In an in vivo model of acute infarct in rats, NAR (100mg/Kg i.p.) significantly reduced the heart injury induced by I/R. This effect was antagonized by the selective BK-blocker paxilline (PAX). The cardioprotective dose of NAR did not cause significant effects on the blood pressure. In Largendorff-perfused rat hearts submitted to ischemia/reperfusion, NAR improved the post-ischemic functional parameters (left ventricle developed pressure and dP/dt) with lower extension of myocardial injury. On isolated rat cardiac mitochondria, NAR caused a concentration-dependent depolarization of mitochondrial membrane and caused a trans-membrane flow of thallium (potassium-mimetic cation). Both these effects were antagonized by selective blockers of BK channels. Furthermore, NAR half-reduced the calcium accumulation into the matrix of cardiac mitochondria exposed to high calcium concentrations. In conclusion, NAR exerts anti-ischemic effects through a "pharmacological preconditioning" that it is likely to be mediated, at least in part, by the activation of mitochondrial BK channels.
[show abstract][hide abstract] ABSTRACT: Hydrogen sulphide (H(2)S) has been recently hypothesized to be an endogenous adipocyte-derived relaxing factor, evoking vasorelaxation of conductance and resistance vessels. Although the activation of ATP-sensitive potassium channels is known to play a central role in H2S-induced vasorelaxation, activation of vascular K(v)7 voltage-gated potassium channels has also been suggested. To investigate this possibility, the ability of selective activators and blockers of distinct classes of potassium channels to affect vasodilation induced by the the H(2)S-donor NaHS, as well as NaHS-induced Rb(+) efflux in endothelium-denuded rat aortic rings, was investigated. NaHS-induced changes of membrane potential were fluorimetrically assessed on human vascular smooth muscle (VSM) cells. Modulation of K(v)7.4 channels by NaHS was assessed by electrophysiological studies, upon their heterologous expression in CHO cells. In isolated aortic rings, NaHS evoked vasorelaxing responses associated with an increase of Rb(+)-efflux. NaHS promoted membrane hyperpolarization of human VSM cells. These effects were antagonized by selective blockers of K(v)7 channels. The H(2)S-donor caused a left-shift of current activation threshold of K(v)7.4 channels expressed in CHO cells. Altogether, these results suggest that the activation of K(v)7.4 channels is a key mechanism in the vascular effects of H(2)S. Given the relevant roles played by K(v)7.4 channels in VSM contractility and by H(2)S in circulatory homeostasis regulation, these findings provide interesting insights to improve our understanding of H(2)S pathophysiology and to focus on K(v)7.4 channels as novel targets for therapeutic approaches via the "H(2)S-system".
Pharmacological Research 12/2012; · 4.35 Impact Factor
[show abstract][hide abstract] ABSTRACT: Hydrogen sulphide (H(2) S) is emerging as an important endogenous modulator, which exhibits the beneficial effects of nitric oxide (NO) on the cardiovascular (CV) system, without producing toxic metabolites. H(2) S is biosynthesized in mammalian tissues by cystathionine-β-synthase and cystathionine-γ-lyase. H(2) S exhibits the antioxidant properties of inorganic and organic sulphites, behaving as a scavenger of reactive oxygen species. There is also clear evidence that H(2) S triggers other important effects, mainly mediated by the activation of ATP-sensitive potassium channels (K(ATP) ). This mechanism accounts for the vasorelaxing and cardioprotective effects of H(2) S. Furthermore, H(2) S inhibits smooth muscle proliferation and platelet aggregation. In non-CV systems, H(2) S regulates the functions of the central nervous system, as well as respiratory, gastroenteric, and endocrine systems. Conversely, H(2) S deficiency contributes to the pathogenesis of hypertension. Likewise, impairment of H(2) S biosynthesis is involved in CV complications associated with diabetes mellitus. There is also evidence of a cross-talk between the H(2) S and the endothelial NO pathways. In particular, recent observations indicate a possible pathogenic link between deficiencies of H(2) S activity and the progress of endothelial dysfunction. These biological aspects of endogenous H(2) S have led several authors to look at this mediator as "the new NO" that has given attractive opportunities to develop innovative classes of drugs. In this review, the main biological actions of H(2) S are discussed. Moreover, some examples of H(2) S-donors are shown, as well as some hybrids, in which H(2) S-releasing moieties are added to well-known drugs, for improving their pharmacodynamic profile or reducing the potential for adverse effects, are reported.
Medicinal Research Reviews 11/2012; 32(6):1093-130. · 9.58 Impact Factor
[show abstract][hide abstract] ABSTRACT: BACKGROUND AND PURPOSE: An important objective in asthma therapy is to prevent the accelerated growth of airway smooth muscle cells which leads to hyperplasia and bronchial hyperreactivity. We investigated the effect of combination of salbutamol and peroxisome proliferator-activated receptor (PPAR)γ agonists on growth factor-stimulated human bronchial smooth muscle cell (BSMC) proliferation. EXPERIMENTAL APPROACH: Synergism was quantified by the combination index-isobologram method. Characterization tools included analyses of growth inhibition, cell viability, DNA fragmentation, gene transcription, cell cycle, and protein expression. KEY RESULTS: The PPARγ gene was highly expressed in BSMC and the protein was identified in cell nuclei. Single-agent salbutamol or PPARγ agonists prevented growth factor-induced human BSMC proliferation within a micromolar range of concentrations through their specific receptor subtypes. Sub-micromolar levels of combined salbutamol-PPARγ agonist inhibited growth by 50% at concentrations from ∼2 to 12-fold lower than those required for each drug alone, without induction of apoptosis or necrosis. Combination treatments also promote cell cycle arrest at the G1/S transition phase and inhibition of ERK phosphorylation. CONCLUSIONS AND IMPLICATIONS: The synergistic interaction between PPARγ agonists and β(2) -adrenoceptor agonists on airway smooth muscle cell proliferation highlights the antiremodeling potential of this combination in chronic lung diseases.
British Journal of Pharmacology 08/2012; · 5.07 Impact Factor
[show abstract][hide abstract] ABSTRACT: Hydrogen sulphide (H(2)S) is now viewed as an important endogenous gasotransmitter, which exhibits many beneficial effects on the cardiovascular system. H(2)S is biosynthesized in mammalian tissues by both non-enzymatic processes and several enzymatic pathways ensured by cystathionine-β-synthase and cystathionine-γ-lyase. H(2)S is endowed with the antioxidant properties of inorganic and organic sulphites, being a scavenger of reactive oxygen species. Furthermore, H(2)S triggers other important effects and the activation of ATP-sensitive potassium channels (KATP) accounts for its vasorelaxing and cardioprotective effects. H(2)S also inhibits smooth muscle proliferation and platelet aggregation. Conversely, the impairment of H(2)S contributes to the pathogenesis of hypertension and is involved in cardiovascular complications associated with diabetes mellitus. There is also evidence of a link between H(2)S and endothelial nitric oxide (NO). Recent observations indicate a possible pathogenic link between deficiencies of H(2)S activity and the progress of endothelial dysfunction. These biological aspects of endogenous H(2)S led to consider this mediator as "the new NO" and to evaluate new attractive opportunities to develop innovative classes of drugs. In this review, the main roles played by H(2)S in the cardiovascular system and the first examples of H(2)S-donor drugs are discussed. Some hybrid drugs are also addressed in this review. In such compounds opportune H(2)S-releasing moieties are conjugated to well-known drugs to improve their pharmacodynamic profile or to reduce the potential for adverse effects.
Current Medicinal Chemistry 06/2012; 19(20):3325-36. · 4.07 Impact Factor
[show abstract][hide abstract] ABSTRACT: Microparticles are membrane vesicles shed by cells upon activation and/or apoptosis. Microparticles are involved in several processes, including blood coagulation and thrombosis. In addition to their role in the regulation of lipid metabolism, peroxisome proliferator-activated receptor-γ (PPAR-γ) agonists exert other effects, both dependent on and independent of PPAR-γ activation. Some PPAR-γ agonists have been linked to an increased risk of thrombotic diseases. We aimed to investigate the potential role of PPAR-γ agonists on the generation of procoagulant microparticles by human monocytes/macrophages.
Monocytes/macrophages were isolated from the buffy coats of normal donors. Cells were incubated with three structurally unrelated PPAR-γ agonists, namely, rosiglitazone, pioglitazone, and 15-deoxy-Δ(12,14)-prostaglandin J(2). Microparticle generation was assessed as phosphatidylserine concentration by a prothrombinase assay, after capturing the microparticles onto annexin V-coated wells. Intracellular calcium concentration was assessed by a fluorescent probe. Extracellular signal-regulated kinase (ERK) phosphorylation was assessed by western blot. Tissue factor expression on microparticles was measured with a one-stage clotting assay. Rosiglitazone and 15-deoxy-Δ(12,14)-prostaglandin J(2), but not pioglitazone, caused a dose-dependent, significant increase in intracellular calcium mobilization and tissue factor-bearing microparticle generation. EGTA inhibited microparticle generation. The specific PPAR-γ inhibitor, GW9662, also inhibited microparticle generation. Finally, rosiglitazone and 15-deoxy-Δ(12,14)-prostaglandin J(2) caused phosphorylation of ERK; inhibition of ERK by PD98059 inhibited microparticle generation.
The PPAR-γ agonists rosiglitazone and 15-deoxy-Δ(12,14)-prostaglandin J(2), but not pioglitazone, caused an increase in procoagulant, tissue factor-bearing microparticle generation by human monocytes/macrophages. The effect was dependent on ERK phosphorylation and partly mediated through intracellular calcium mobilization; however, direct activation of the PPAR-γ ligand was also involved.
Cardiovascular research 03/2012; 94(3):537-44. · 5.80 Impact Factor
[show abstract][hide abstract] ABSTRACT: Nowadays, many people still fall victim to tuberculosis, the disease that has a worldwide spreading. Moreover, the problem of resistance to isoniazid and rifampin, the two most effective antitubercular drugs, is assuming an ever-growing importance. The need for new drugs active against Mycobacterium tuberculosis represents nowadays a quite relevant problem in medicinal chemistry. Several purine and 2,3-dihydropurine derivatives have recently emerged, showing considerable antitubercular properties. In this work, a quantitative structure-activity relationship (QSAR) model was developed, which is able to predict whether new purine and 2,3-dihydropurine derivatives belong to an 'Active' or 'Inactive' class against the above micro-organism. The obtained prediction model is based on a classification tree; it was built with a small number of descriptors, which allowed us to outline structural features important to predict antitubercular activity of such classes of compounds.
Chemical Biology & Drug Design 07/2011; 78(4):718-24. · 2.47 Impact Factor
[show abstract][hide abstract] ABSTRACT: The activation of ATP-sensitive potassium channels (K(ATP)), play a key role in an endogenous "self-defence" mechanism, known as ischemic preconditioning (IPC), which is fundamentally involved in the protection of the heart against the ischemia/reperfusion injury. Presently, it is widely accepted that IPC is mainly (albeit not exclusively) mediated by the activation of K(ATP) channels expressed in the mitochondrial inner membrane (mito-K(ATP)) rather than the sarcoplasmatic ones (sarc-K(ATP)). Consistently, exogenous activation of K(ATP) channels by pharmacological tools can be viewed as one of the most promising strategies for the therapy of myocardial ischemia. As part of our research program devoted to the synthesis and the evaluation of new cardioprotective agents, we extensively studied several six-membered spiro-heterocycle-benzopyran compounds endowed of a significant anti-ischemic activity. The positive results obtained, prompted us to further explore the influence on the biopharmacological effects, of the spiro-substitution at C4 benzopyran nucleus by replacing the six-membered spirocycle of the most active compounds with 5-membered-one. The preliminary evaluation of the new compounds on cultured H9c2 cardiomyoblasts exposed to anoxia/reperfusion and on Langendorff-perfused rat hearts submitted to ischemia/reperfusion cycles, showed that some of them can exert a cardioprotective effect. This anti-ischemic activity was antagonized by 5-hydroxydecanoic acid, a selective blocker of mito-K(ATP) channels, confirming the involvement of this channel in the cardioprotective activity.
European journal of medicinal chemistry 03/2011; 46(3):966-73. · 3.27 Impact Factor
[show abstract][hide abstract] ABSTRACT: β₂-Adrenoceptor agonists are important therapeutic agents in the treatment of asthma and chronic obstructive pulmonary disease. The regular use of these drugs has been associated with proasthmatic-like changes that limit their efficacy and increase the risk of severe adverse reactions. We investigated whether the peroxisome-proliferator-activated receptor (PPAR)γ agonist rosiglitazone modulated salbutamol-induced β₂-adrenoceptor desensitization in vivo and in vitro.
An in vivo model of homologous β₂-adrenoceptor desensitization, established in guinea-pigs by administering salbutamol continuously, was used to study the ability of rosiglitazone to prevent β₂-adrenoceptor tolerance. In vitro experiments on human bronchial smooth muscle cells were performed to increase the clinical relevance of the study.
In tracheal smooth muscle tissues from desensitized animals, we observed a decrease in the protective effect of salbutamol on carbachol-induced contraction, a hyperresponsiveness to cholinergic stimuli, a modest underexpression of β₂-adrenoceptor gene and a marked decrease in β-adrenoceptor number, relative to control values. Treatment with rosiglitazone preserved salbutamol relaxant activity, mitigated carbachol hyperresponsiveness and partially restored β₂-adrenoceptor binding sites in tracheal tissues from homologously desensitized animals. The highly selective PPARγ agonist, GW1929, reproduced the effect of rosiglitazone, in vivo. In vitro β₂-adrenoceptor desensitization decreased salbutamol-mediated cAMP production, without affecting forskolin responses and β₂-adrenoceptor expression. Rosiglitazone and 15-deoxy-Δ¹²(,)¹⁴-prostaglandin J₂ restored salbutamol sensitivity in homologously desensitized cells.
These data suggest a potential pharmacodynamic interaction between PPARγ agonists and salbutamol on airway smooth muscle responsiveness, supporting the therapeutic potential of this combination in chronic airway disease.
British Journal of Pharmacology 01/2011; 162(2):378-91. · 5.07 Impact Factor
[show abstract][hide abstract] ABSTRACT: A new mathematical model, referred to as Enhancer and Competitive Allosteric Modulator (ECAM) model, developed with the aim of quantitatively describing the interaction of an allosteric modulator with both enhancer and competitive properties towards G-protein-coupled receptors is described here. Model simulations for equilibrium (displacement-like and saturation-like), and kinetic (association and dissociation) binding experiments were performed. The results showed the ability of the model to interpret a number of possible ligand-receptor binding behaviors. In particular, the binding properties of PD81723, an enhancer and competitive allosteric modulator for the adenosine A(1) receptor, were experimentally evaluated by radioligand binding assays and interpreted by the ECAM model. The results also offer a theoretical background enabling the design and optimization of compounds endowed with allosteric enhancer, competitive, agonist, antagonist, and inverse agonist properties.
Journal of Theoretical Biology 12/2010; 267(4):663-75. · 2.35 Impact Factor
[show abstract][hide abstract] ABSTRACT: Microparticles (MP) are phospholipid vesicles shed by cells upon activation or apoptosis. Monocyte-derived MP upregulate the synthesis of proinflammatory mediators by lung epithelial cells; the molecular bases of such activity are unknown. Peroxisome proliferator-activated receptors (PPAR) have been demonstrated to be involved in the modulation of nuclear factor (NF)-κB transcriptional activity and inflammation. We investigated whether the upregulation of the synthesis of proinflammatory cytokines by human lung epithelial cells induced by monocyte/macrophage-derived MP involves NF-κB activation and is modulated by PPAR-γ. MP were generated by stimulation of human monocytes/macrophages with the calcium ionophore, A23187. MP were incubated with human lung epithelial cells. NF-κB translocation was assessed by electrophoretic mobility shift assay. Interleukin (IL)-8 and monocyte chemotactic protein (MCP)-1 synthesis was assessed by ELISA and RT-PCR. Stimulation of A549 alveolar cells with monocyte/macrophage-derived MP caused an increase in NF-κB activation and IL-8 and MCP-1 synthesis that was inhibited by pre-incubation with the PPAR-γ agonists, rosiglitazone and 15-deoxy-Δ12,14-prostaglandin-J2. Parallel experiments with normal human bronchial epithelial cells largely confirmed the results. The effects of PPAR-γ agonists were reversed by the specific antagonist, GW9662. Upregulation of the synthesis of proinflammatory mediators by human lung epithelial cells induced by monocyte/macrophage-derived MP is mediated by NF-κB activation through a PPAR-γ dependent pathway.
European Respiratory Journal 12/2010; 37(6):1494-502. · 6.36 Impact Factor
[show abstract][hide abstract] ABSTRACT: The non-steroidal anti-inflammatory drug (NSAID) sulindac exhibits cyclooxygenase (COX)-dependent and COX-independent chemopreventive properties in human cancer. The present study was aimed at investigating whether the hydroxamic acid substitution for the carboxylic acid group could enhance the in vitro antitumor and antiangiogenic activities of sulindac. Characterization tools used on this study included analyses of cell viability, caspase 3/7 induction, DNA fragmentation, and gene expression. Our findings demonstrate that the newly synthesized hydroxamic acid derivative of sulindac and its sulfone and sulfide metabolites were characterized by a good anticancer activity on human pancreatic and colon cancer cells, both in terms of potency (IC(50) mean values from 6 ± 1.1 μM to 64 ± 1.1 μM) and efficacy (E(max) of ∼100%). Hydroxamic acid derivatives trigger a higher degree of apoptosis than carboxylic acid counterparts, increase bax/bcl-2 expression ratio and induce caspase 3/7 activation. Most notably, these compounds significantly inhibit proangiogenic growth factor-stimulated proliferation of vascular endothelial cell (HUVEC) at sub-micromolar concentrations. Our data also provide evidence that the COX-active metabolite of sulindac hydroxamic acid were the most active of the series and selective inhibition of COX-1 but not COX-2 can mimic its effects, suggesting that COX inhibition could only play a partial role in the mechanism of compound action. In conclusion, these data demonstrate that substitution of the carboxylic acid group with the hydroxamic acid moiety enhances in vitro antiproliferative, proapoptotic and antiangiogenic properties of sulindac, therefore increasing the therapeutic potential of this drug.
European journal of medicinal chemistry 11/2010; 45(11):5100-7. · 3.27 Impact Factor
[show abstract][hide abstract] ABSTRACT: This work evaluated the potential usefulness of pharmacological activation of cardiac ATP-sensitive potassium channels (K(ATP)) in the prevention of drug-induced QT prolongation in anaesthetised guinea-pigs. Prolongation of cardiac repolarisation and QT interval is an adverse effect of many drugs blocking HERG potassium channels. This alteration can be dangerously arrhythmogenic and has been associated with the development of a particular form of ventricular tachyarrhythmia known as torsade de pointes.
The well-known K(ATP) openers aprikalim, cromakalim and pinacidil were used. Moreover, three benzothiazine derivatives, which have been reported as potent activators of K(ATP) channels, were also used.
Pharmacological activation of K(ATP) channels caused a reduction of the QT prolongation, induced by astemizole, cisapride, quinidine and thioridazine. In contrast, the QT prolongation induced by haloperidol, sotalol and terfenadine, which are known to block HERG channels but also K(ATP) channels, was not influenced by K(ATP) activation. Glibenclamide and tolbutamide (non-selective blockers of K(ATP) channels expressed both in sarcolemmal and in mitochondrial membranes) antagonised the effects of K(ATP) openers, whereas 5-hydroxydecanoic acid (selective blocker of the mitochondrial K(ATP) channels) failed to antagonise the effects of K(ATP) openers, indicating that only the sarcolemmal K(ATP) is involved in the cardioprotective activity.
The data suggest that pharmacological K(ATP) activation might represent an option for treatment of patients exposed to QT-prolonging drugs.
The Journal of pharmacy and pharmacology. 07/2010; 62(7):924-30.