Clara Cena

Searching for new NO-donor Aspirin-like molecules: a new class of nitrooxy-acyl derivatives of salicylic acid

A new class of products in which the phenol group of salicylic acid is linked to alkanoyl moieties bearing nitrooxy functions has been synthesized and studied for their polyvalent actions. The products were stable in acid and neutral media, while they were hydrolyzed in human serum. Their half-lives were dependent upon the structure of alkanoyl moieties. The products showed anti-inflammatory activities similar to aspirin when tested in the carrageenan-induced paw edema assay in the rat. Interestingly, unlike aspirin, they showed reduced or no gastrotoxicity in a lesion model in rats at equimolar doses. A number of them were able to inhibit platelet aggregation induced by collagen in human platelet-rich plasma. All of the products were capable of relaxing rat aortic strips precontracted with phenylephrine in a concentration-dependent manner. Selected members of this new class of nonsteroidal anti-inflammatory drugs might represent possible safer alternatives to aspirin in different clinical settings.

A novel hybrid aspirin-NO-releasing compound inhibits TNFalpha release from LPS-activated human monocytes and macrophages

BackgroundThe cytoprotective nature of nitric oxide (NO) led to development of NO-aspirins in the hope of overcoming the gastric side-effects of aspirin. However, the NO moiety gives these hybrids potential for actions further to their aspirin-mediated anti-platelet and anti-inflammatory effects. Having previously shown that novel NO-aspirin hybrids containing a furoxan NO-releasing group have potent anti-platelet effects, here we investigate their anti-inflammatory properties. Here we examine their effects upon TNFα release from lipopolysaccharide (LPS)-stimulated human monocytes and monocyte-derived macrophages and investigate a potential mechanism of action through effects on LPS-stimulated nuclear factor-kappa B (NF-κB) activation.MethodsPeripheral venous blood was drawn from the antecubital fossa of human volunteers. Mononuclear cells were isolated and cultured. The resultant differentiated macrophages were treated with pharmacologically relevant concentrations of either a furoxan-aspirin (B8, B7; 10 μM), their respective furazan NO-free counterparts (B16, B15; 10 μM), aspirin (10 μM), existing nitroaspirin (NCX4016; 10 μM), an NO donor (DEA/NO; 10 μM) or dexamethasone (1 μM), in the presence and absence of LPS (10 ng/ml; 4 h). Parallel experiments were conducted on undifferentiated fresh monocytes. Supernatants were assessed by specific ELISA for TNFα release and by lactate dehydrogenase (LDH) assay for cell necrosis. To assess NF-κB activation, the effects of the compounds on the loss of cytoplasmic inhibitor of NF-κB, IκBα (assessed by western blotting) and nuclear localisation (assessed by immunofluorescence) of the p65 subunit of NF-κB were determined.ResultsB8 significantly reduced TNFα release from LPS-treated macrophages to 36 ± 10% of the LPS control. B8 and B16 significantly inhibited monocyte TNFα release to 28 ± 5, and 49 ± 9% of control, respectively. The B8 effect was equivalent in magnitude to that of dexamethasone, but was not shared by 10 μM DEA/NO, B7, the furazans, aspirin or NCX4016. LDH assessment revealed none of the treatments caused significant cell lysis. LPS stimulated loss of cytoplasmic IκBα and nuclear translocation of the p65 NF-κB subunit was inhibited by the active NO-furoxans.ConclusionHere we show that furoxan-aspirin, B8, significantly reduces TNFα release from both monocytes and macrophages and suggest that inhibition of NF-κB activation is a likely mechanism for the effect. This anti-inflammatory action highlights a further therapeutic potential of drugs of this class.

Edaravone derivatives containing NO-donor functions.

A new series of polyvalent drugs obtained by joining edaravone with NO-donor moieties is described. All compounds display high antioxidant power together with NO-dependent vasodilator properties. The analysis of a number of molecular descriptors shows that the antioxidant activity, which is tightly linked to the presence of the edaravone substructure, is principally modulated by lipophilicity. These products are potentially useful in the treatment of cardiovascular disorders in which EDRF deficiency and ROS excess are involved.

Nitrooxyacyloxy)methyl Esters of Aspirin as Novel Nitric Oxide Releasing Aspirins

A series of (nitrooxyacyloxy)methyl esters of aspirin were synthesized and evaluated as new NO-donor aspirins. Different amounts of aspirin were released in serum from these products according to the nature of nitrooxyacyloxy moiety present. In the aromatic series, there is a rather good linear correlation between the amount of aspirin released and the potencies of the products in inhibiting platelet aggregation induced by collagen. Both the native compounds and the related nitrooxy-substituted acid metabolites were able to relax rat aorta strips precontracted with phenylephrine, in keeping with a NO-induced activation of the sGC as a mechanism that underlies the vasodilator effect. The products here described are new improved examples of NO-donor aspirins containing nitrooxy groups. They could represent an alternative to the use of aspirin in a variety of clinical applications.

Searching for new NO-donor aspirin-like molecules: Furoxanylacyl derivatives of salicylic acid and related furazans.

A new group of derivatives of salicylic acid containing NO-donor furoxans, and the related des-NO-furazans, were synthesized and evaluated as new aspirin-like molecules. Their stability was assessed in acid (pH 1) and physiological solutions (pH 7.4), and in human serum. No compound exhibited COX-inhibitory activity against COX-1 and COX-2 isoforms, when tested up to 100μM, respectively, on isolated platelets and on monocytes. Phenylsulfonyl- and cyano-substituted furoxans inhibited platelet aggregation induced by collagen in human platelet-rich plasma, through a cGMP dependent mechanism. Furoxan derivatives displayed cGMP-dependent vasodilator activities, tested on rat aorta strips precontracted with phenylephrine. All products showed anti-inflammatory activity similar to that of ASA, tested on rats by the carrageenan-induced paw edema assay. Unlike ASA, all products showed markedly reduced gastrotoxicity in a rat lesion model.

Nitrooxymethyl-Substituted Analogues of Rofecoxib: Synthesis and Pharmacological Characterization

Nitrooxymethyl‐substituted derivatives of Rofecoxib were synthesized and tested for their cyclooxygenase (COX)‐inhibiting activity in whole human blood, vasodilator potency on rat aorta strips, and for their capacity of inhibiting platelet aggregation of human platelet‐rich plasma. The results show that their potency and selectivity in inhibiting COX isoforms, as well as their anti‐aggregatory properties, are closely dependent on the position at which the NO‐donor nitrooxymethyl function is introduced into the Rofecoxib scaffold. All the products were capable of dilating rat aorta strips precontracted with phenylephrine in a dose‐dependent manner, through a cGMP‐dependent mechanism. Compound 10 emerged as a quite potent COX‐2‐selective inhibitor endowed with good vasodilator activity. Interestingly, compound 19 behaved as a potent selective COX‐1 inhibitor, and displayed good vasodilator and anti‐aggregatory properties. The hydroxymethyl derivatives, potential metabolites of the nitrooxymethyl analogues, were similarly studied for a comparison.

Multitarget drugs: Focus on the NO-donor hybrid drugs

The article addresses the design of multitarget drugs, namely, compounds capable of interacting with more than one target simultaneously. These agents could be useful tools in the therapy of complex diseases such as cardiovascular and inflammatory diseases. An interesting case of multitarget compounds are nitric oxide (NO)-donor hybrids, structures which combine the physiological properties of NO with those of a lead drug. In particular, the authors discuss the symbiotic approach used to design NO-donor nonsteroidal anti-inflammatory drugs (NO-NSAIDs) and NO-donor antioxidants. The former could be useful agents in the treatment of anti-inflammatory diseases being devoid of gastro- and cardiotoxicity, the latter could be a valid approach to the treatment of many cardiovascular diseases.

A new furoxan NO-donor rabeprazole derivative and related compounds.

The design of hybrid molecules by combining appropriate pharmacophoric groups with NO-releasing moieties is a promising approach to the production of new drugs with interesting potential for treating a variety of diseases. Our research group has been active in this field and we have designed several such products. These compounds include NO-donor nonsteroidal antiinflammatory drugs (NSAIDs) 5] and NO-donor H2-receptor antagonists. We pursued this line because nitric oxide (NO.) has protective effects on the gastric mucosa through a number of mechanisms, such as promotion of mucus secretion, increased mucosal blood flow and decreased adherence of neutrophils to the gastric vascular endothelium. In confirmation of this idea, we herein describe the new hybrid 12, obtained by joining the 4-alkoxy-3-phenylsulfonylfuroxan substructure to rabeprazole (1; Scheme 1). It is known that furoxans are able to release NO at physiological pH, in the presence of thiol cofactors. The mechanism of this release appears to be complex and may contributed to the dramatic T1 relaxivity changes. Gd±DTPA alone did not provide any meaningful enhancement of the signal, even when a 600-fold excess was used in the experiment. In conclusion, we have developed new types of imaging probes that have the potential to be used for in vivo imaging of blood coagulation. The specific peptide derived from 2AP labeled with various reporter groups can be covalently attached to fibrin by blood coagulation factor FX13 through transglutamination. Theoretically, the same approach could be applied to other transglutaminases, which are widely found in generic tissue stabilization and also contribute to a variety of diseases, such as cancer, neurodegenerative diseases, and celiac disease. 18]

Antisecretory and gastroprotective activities of compounds endowed with H2 antagonistic and nitric oxide (NO) donor properties

In spite of the well recognized gastric antisecretory activity, the gastroprotective potential of histamine H2 receptor antagonists is controversial. Most clinical studies in fact indicate that these drugs do not substantially protect the gastric mucosa from aggressive factors. Nitric oxide (NO) has been recently recognized as a fundamental mediator in gastric defence mechanisms, due to its ability to increase gastric mucosal blood flow and mucus production and to inhibit neutrophils adherence to endothelial cells. The aim of this study was to investigate the gastroprotective and H2 receptor antagonistic activity of a series of lamtidine analogues which contain different NO-releasing moieties (furoxan, nitroxy and nitrosothiol). These compounds were tested, in comparison with related H2 antagonists devoid of NO-donor structures, in different H2 receptor assays and in the conscious rat against 0.6 N HCl-induced gastric lesions. All the compounds tested were able to antagonize histamine-mediated responses at cardiac and gastric H2 receptors; however, furoxan and nitroxy derivatives were 10-fold less potent than the analogues devoid of NO-donor properties. By contrast, NO-donor compounds were more active than reference H2 antagonists as gastroprotective agents against mucosal injury induced by 0.6 N HCl. Among the different NO-donor moieties, the furoxan group conferred to the H2 antagonist molecule the highest gastroprotective potential; this finding closely correlates with the characteristics of NO release. In conclusions, lamtidine-analogue H2 antagonists combined with NO-donor moieties are endowed with gastric antisecretory and protective activity and could be the prototypes of a new class of anti-ulcer drugs. Finally, the furoxan NO donor group seems to be the most favourable among the different moieties tested.

Designing Multitarget Anti‐inflammatory Agents: Chemical Modulation of the Lumiracoxib Structure toward Dual Thromboxane Antagonists–COX‐2 Inhibitors

A series of lumiracoxib derivatives were designed to explore the influence of isosteric substitution on balancing COX‐2 inhibition and thromboxane A2 prostanoid (TP) receptor antagonism. The compounds were synthesized through a copper‐catalyzed coupling procedure and characterized for their pKa values. TP receptor antagonism was assessed on human platelets; COX‐2 inhibition was determined on human isolated monocytes and human whole blood. TPα receptor binding of the most promising compounds was evaluated through radioligand binding assays. Some of the isosteric substitutions at the carboxylic acid group afforded compounds with improved TP receptor antagonism; of these, a tetrazole derivative retained good COX‐2 inhibitory activity and selectivity. The identification of this tetrazole acting as a balanced dual‐acting compound in human whole blood, along with SAR analysis of the synthesized lumiracoxib derivatives, might contribute to the rational design of a new class of cardioprotective anti‐inflammatory agents.