Selective nitros(yl)ation induced in vivo by a nitric oxide-donating cyclooxygenase-2 inhibitor: a NObonomic analysis

Design, synthesis, modeling studies and biological evaluation of pyrazole derivatives linked to oxime and nitrate moieties as nitric oxide donor selective COX-2 and aromatase inhibitors with dual anti-inflammatory and anti-neoplastic activities

Two new series of pyrazole derivatives 10a-f and 11a-f with selective COX-2 inhibition pharmacophore and oxime/nitrate moieties as NO donor moiety were designed, synthesized and tested for anti-inflammatory, cytotoxic activities and NO release. Compounds 10c, 11a, 11e were more selective for COX-2 isozyme (S.I. = 25.95, 22.52 and 21.54 respectively) in comparison to celecoxib (S.I. = 21.41). Regarding anti-cancer activity, all synthesized compounds were screened by the National Cancer Institute (NCI), Bethesda, USA for anticancer activity against 60 human cancer cell lines representing the following cancer types: leukemia, non-small cell lung, colon, CNS, melanoma, ovarian, renal, prostate, and breast cancers. Compounds 10c, 11a, 11e were found to be the most potent inhibitors on breast, ovarian and melanoma cell lines (MCF-7, IGROV1 and SK-MEL-5), compound 11a causing 79 % inhibition in case of MCF-7, 78.80 % inhibition in case of SK-MEL-5 and unexpected cell growth -26.22 % inhibition in case of IGROV1 (IC₅₀ = 3.12, 4.28, 4.13 μM respectively). On the other hand, compounds 10c and 11e showed lower inhibition on the same cell lines with IC₅₀ = 3.58, 4.58, 4.28 μM respectively for 10c, IC₅₀ = 3.43, 4.73, 4.43 μM respectively for 11e. Furthermore, DNA-flow cytometric analysis showed that compound 11a induces cell cycle arrest at G2/M phase leading to cell proliferation inhibition and apoptosis. Additionally, these derivatives examined against F180 fibroblasts to investigate their selectivity indexes. The pyrazole derivative with internal oxime 11a was the most potent compound against most used cell lines especially MCF-7, IGROV1 and SK-MEL-5 (IC₅₀ = 3.12, 4.28, 4.13 μM respectively) with 4.82-fold selectivity towards MCF-7 than F180 fibroblasts. Moreover, oxime derivative 11a showed potent aromatase inhibitory activity (IC₅₀ 16.50 μM) when compared with reference compound letrozole (IC₅₀ 15.60 μM). All compounds 10a-f and 11a-f released NO in a slow rate (0.73-3.88 %) and the six derivatives 10c, 10e, 11a, 11b, 11c and 11e were the highest NO releasers (3.88, 2.15, 3.27, 2.27, 2.55 and 3.74 % respectively). Herein structure based and ligand based studies were implemented to under stand and evaluate the compounds activity for further in vivo and preclinical studies. Docking mode of final designed compounds with celecoxib (ID: 3LN1) represented that their triazole ring adopted as the core aryl in Y shaped structure. Regarding aromatase enzyme inhibition, docking was carried out with ID: 1 M17. The internal oxime series was more active as anticancer because of their ability to form extra HBs with receptor cleft.

The evolving landscape for cellular nitric oxide and hydrogen sulfide delivery systems: A new era of customized medications

Nitric oxide (NO) and hydrogen sulfide (H2S) are industrial toxins or pollutants; however, both are produced endogenously and have important biological roles in most mammalian tissues. The recognition that these gasotransmitters have a role in physiological and pathophysiological processes has presented opportunities to harness their intracellular effects either through inhibition of their production; or more commonly, through inducing their levels and or delivering them by various modalities. In this review article, we have focused on an array of NO and H2S donors, their hybrids with other established classes of drugs, and the various engineered delivery platforms such a fibers, polymers, nanoparticles, hydrogels, and others. In each case, we have reviewed the rationale for their development.

Novel (pyrazolyl)benzenesulfonamides with a nitric oxide-releasing moiety as selective cyclooxygenase-2 inhibitors

Inhibition of cyclooxygenase-2 (COX-2) is a promising anti-inflammatory therapeutic strategy, but long-term medication with COX-2-inhibitors (coxibs) may be associated with adverse cardiovascular effects. Functionalization of existing lead structures with nitric oxide (NO)-releasing moieties is an auspicious approach to minimize these effects. In this regard, an organic nitrate (-O-NO2) substituent was introduced at a (pyrazolyl)benzenesulfonamide lead structure. The novel NO-coxibs selectively inhibited COX-2 in a low micromolar range (IC50(COX-2): 0.22-1.27 μM) and are supposed to be promising anti-inflammatory compounds with, in parallel, positive effects on vascular homeostasis.

Synthesis of thiophene and NO-curcuminoids for antiinflammatory and anti-cancer activities

In search of better NSAIDs four novel nitric oxide donating derivatives of curcumin (compounds 9a–d), and four thiophene curcuminoids (compounds 10a–c, 11) have been synthesised. The cytotoxic effects of these compounds along with the lead compound curcumin (7) and their effect on the production of the reactive oxygen species nitric oxide and pro-inflammatory cytokines IL-1β, TNF-α and chemokine CXCL-8 were evaluated using human monocytic THP-1 and colon adenocarcinoma CACO-2 cell lines. All of the nitric oxide donating curcuminoids 9a–d and the thiophene curcuminoids 10a–c and 11 were non-cytotoxic to THP-1 cells over a concentration range of 10-100 μM and compared with curcumin compounds 10b and 10c, were more toxic. In CACO-2 cells, 10b and 11 appeared to be non-toxic at 10 to 50 μM, whereas 10a and 10c were non-cytotoxic at 10 μM only. These results clearly indicate that the introduction of a nitroxybutyl moiety to curcumin and replacement of phenyl rings with thiophene units reduces the cytotoxic effect of the parent curcumin, whereas a methyl substituted thiophene increases the cytotoxic effects. In THP-1 cells, drugs 10a and 11 significantly decreased IL-1-β production at their non-cytotoxic concentrations, whereas, they did not decrease TNF-α production in CACO-2 cells. Compound 11 showed a significant decrease in CXCL-8 production.

Celecoxib analogs possessing a N-(4-nitrooxybutyl)piperidin-4-yl or N-(4-nitrooxybutyl)-1,2,3,6-tetrahydropyridin-4-yl nitric oxide donor moiety: synthesis, biological evaluation and nitric oxide release studies

A new group of hybrid nitric oxide (NO) releasing anti-inflammatory (AI) coxib prodrugs (NO-coxibs) wherein the para-tolyl moiety present in celecoxib was replaced by a N-(4-nitrooxybutyl)piperidyl 15a-b, or N-(4-nitrooxybutyl)-1,2,3,6-tetrahydropyridyl 17a-b, NO-donor moiety was synthesized. All compounds released a low amount of NO upon incubation with phosphate buffered saline (PBS) at pH 7.4 (2.4-5.8% range). In comparison, the percentage NO released was higher (3.1-8.4% range) when these nitrate prodrugs were incubated in the presence of L-cysteine. In vitro COX-1/COX-2 isozyme inhibition studies showed this group of compounds are moderately more potent, and hence selective, inhibitors of the COX-2 relative to the COX-1 enzyme. AI structure-activity relationship data acquired showed that compounds having a MeSO2 COX-2 pharmacophore exhibited superior AI activity compared to analogs having a H2NSO2 substituent. Compounds having a MeSO2 COX-2 pharmacophore in conjunction with a N-(4-nitrooxybutyl)piperidyl (ED50=132.4 mg/kg po), or a N-(4-nitrooxybutyl)-1,2,3,6-tetrahydropyridyl (ED50=118.4 mg/kg po), moiety exhibited an AI potency profile that is similar to aspirin (ED50=128.7 mg/kg po) but lower than ibuprofen (ED50=67.4 mg/kg po).

Inhibition of arginase activity enhances inflammation in mice with allergic airway disease, in association with increases in protein S-nitrosylation and tyrosine nitration

Pulmonary inflammation in asthma is orchestrated by the activity of NF-kappaB. NO and NO synthase (NOS) activity are important modulators of inflammation. The availability of the NOS substrate, l-arginine, is one of the mechanisms that controls the activity of NOS. Arginase also uses l-arginine as its substrate, and arginase-1 expression is highly induced in a murine model of asthma. Because we have previously described that arginase affects NOx content and interferes with the activation of NF-kappaB in lung epithelial cells, the goal of this study was to investigate the impact of arginase inhibition on the bioavailability of NO and the implications for NF-kappaB activation and inflammation in a mouse model of allergic airway disease. Administration of the arginase inhibitor BEC (S-(2-boronoethyl)-l-cysteine) decreased arginase activity and caused alterations in NO homeostasis, which were reflected by increases in S-nitrosylated and nitrated proteins in the lungs from inflamed mice. In contrast to our expectations, BEC enhanced perivascular and peribronchiolar lung inflammation, mucus metaplasia, NF-kappaB DNA binding, and mRNA expression of the NF-kappaB-driven chemokine genes CCL20 and KC, and lead to further increases in airways hyperresponsiveness. These results suggest that inhibition of arginase activity enhanced a variety of parameters relevant to allergic airways disease, possibly by altering NO homeostasis.

Synthesis of new 4-[2-(4-methyl(amino)sulfonylphenyl)-5-trifluoromethyl-2H-pyrazol-3-yl]-1,2,3,6-tetrahydropyridines: a search for novel nitric oxide donor anti-inflammatory agents

A group of 4-[2-(4-methyl(amino)sulfonylphenyl)-5-trifluoromethyl-2H-pyrazol-3-yl]-1,2,3,6-tetrahydropyridines possessing a variety of substituents (Me, CO2Et, H, N=O) attached to the 1,2,3,6-tetrahydropyridyl N(1)-nitrogen atom were synthesized and evaluated as anti-inflammatory agents. Structure-activity relationship data showed that the N-methyl-1,2,3,6-tetrahydropyridyl moiety is a suitable bioisosteric replacement for the tolyl moiety in celecoxib. The most potent compound 4-[5-(1-methyl-1,2,3,6-tetrahydropyridin-4-yl)-3-trifluoromethylpyrazol-1-yl]benzenesulfonamide (ED(50)=61.2 mg/kg po) exhibited an anti-inflammatory activity between that of the reference drugs celecoxib (ED(50)=10.8 mg/kg po) and aspirin (ED(50)=128.7 mg/kg po). The synthesis of model hybrid nitric oxide donor N-diazen-1-ium-1,2-diolate derivatives of 4-[2-(4-methyl(amino)sulfonylphenyl)-5-trifluoromethyl-2H-pyrazol-3-yl]-1,2,3,6-tetrahydropyridines requires further investigation since the reaction of 1,2,3,6-tetrahydropyridines with nitric oxide furnished the undesired N-nitroso-1,2,3,6-tetrahydrohydropyridyl product rather than the desired N-diazen-1-ium-1,2-diolate-1,2,3,6-tetrahydropyridyl product.

Oxidative-nitrosative stress and post-translational protein modifications: implications to lung structure-function relations. Arginase modulates NF-kappaB activity via a nitric oxide-dependent mechanism

NF-kappaB is a versatile transcription factor that regulates a wide array of processes, including inflammation and survival, and plays a critical role in the etiology of inflammatory lung diseases. Nitric oxide (NO) has been suggested to play an antiinflammatory role through S-nitrosation of components of NF-kappaB pathway. NO production can be modulated by changing the availability of its substrate, L-arginine. Arginases compete with NO synthases (NOSs) for their common substrate, L-arginine, and thereby have the potential to alter the signaling function of NO. The goal of the present study was to determine the impact of arginase manipulation on NO, and subsequent effects on NF-kappaB activation, in lung epithelial cells. Our results demonstrate that reduction of arginase activity enhanced cellular content of NO and S-nitrosated proteins, and resulted in decreases in TNF-alpha- or LPS-stimulated NF-kappaB DNA binding and transcriptional activity, in association with enhanced S-nitrosation of p50. The effects of arginase inhibition on NF-kappaB were reversed by the generic NOS inhibitor, N-omega-nitro-L-arginine methyl ester (L-NAME), suggesting a causal role for NO in the attenuation of NF-kappaB induced by arginase suppression. Conversely, overexpression of arginase I decreased cellular S-nitrosothiol content and enhanced IkappaB kinase activity and NF-kappaB DNA binding, and decreased S-nitrosation of p50. Collectively, our data point to a regulatory mechanism wherein NF-kappaB is controlled through arginase-dependent regulation of NO levels, which may impact on chronic inflammatory diseases that are accompanied by NF-kappaB activation and upregulation of arginases.

Anti-inflammatory drugs in the 21st century

Historically, anti-inflammatory drugs had their origins in the serendipitous discovery of certain plants and their extracts being applied for the relief of pain, fever and inflammation. When salicylates were discovered in the mid-19th century to be the active components of Willow Spp., this enabled these compounds to be synthesized and from this, acetyl-salicylic acid or Aspirin was developed. Likewise, the chemical advances of the 19th-20th centuries lead to development of the non-steroidal anti-inflammatory drugs (NSAIDs), most of which were initially organic acids, but later non-acidic compounds were discovered. There were two periods of NSAID drug discovery post-World War 2, the period up to the 1970's which was the pre-prostaglandin period and thereafter up to the latter part of the last century in which their effects on prostaglandin production formed part of the screening in the drug-discovery process. Those drugs developed up to the 1980-late 90's were largely discovered empirically following screening for anti-inflammatory, analgesic and antipyretic activities in laboratory animal models. Some were successfully developed that showed low incidence of gastro-intestinal (GI) side effects (the principal adverse reaction seen with NSAIDs) than seen with their predecessors (e.g. aspirin, indomethacin, phenylbutazone); the GI reactions being detected and screened out in animal assays. In the 1990's an important discovery was made from elegant molecular and cellular biological studies that there are two cyclo-oxygenase (COX) enzyme systems controlling the production of prostanoids [prostaglandins (PGs) and thromboxane (TxA2)]; COX-1 that produces PGs and TxA2 that regulate gastrointestinal, renal, vascular and other physiological functions, and COX-2 that regulates production of PGs involved in inflammation, pain and fever. The stage was set in the 1990's for the discovery and development of drugs to selectively control COX-2 and spare the COX-1 that is central to physiological processes whose inhibition was considered a major factor in development of adverse reactions, including those in the GI tract. At the turn of this century, there was enormous commercial development following the introduction of two new highly selective COX-2 inhibitors, known as coxibs (celecoxib and rofecoxib) which were claimed to have low GI side effects. While found to have fulfilled these aims in part, an alarming turn of events took place in the late 2004 period when rofecoxib was withdrawn worldwide because of serious cardiovascular events and other coxibs were subsequently suspected to have this adverse reaction, although to a varying degree. Major efforts are currently underway to discover why cardiovascular reactions took place with coxibs, identify safer coxibs, as well as elucidate the roles of COX-2 and COX-1 in cardiovascular diseases and stroke in the hope that there may be some basis for developing newer agents (e.g. nitric oxide-donating NSAIDs) to control these conditions. The discovery of the COX isoforms led to establishing their importance in many non-arthritic or non-pain states where there is an inflammatory component to pathogenesis, including cancer, Alzheimer's and other neurodegenerative diseases. The applications of NSAIDs and the coxibs in the prevention and treatment of these conditions as well as aspirin and other analogues in the prevention of thrombo-embolic diseases now constitute one of the major therapeutic developments of the this century. Moreover, new anti-inflammatory drugs are being discovered and developed based on their effects on signal transduction and as anti-cytokine agents and these drugs are now being heralded as the new therapies to control those diseases where cytokines and other nonprostaglandin components of chronic inflammatory and neurodegenerative diseases are manifest. To a lesser extent safer application of corticosteroids and the applications of novel drug delivery systems for use with these drugs as well as with NSAIDs also represent newer technological developments of the 21st century. What started out as drugs to control inflammation, pain and fever in the last two centuries now has exploded to reveal an enormous range and type of anti-inflammatory agents and discovery of new therapeutic targets to treat a whole range of conditions that were never hitherto envisaged.

Detection of nitros(yl)ated metabolites of nitric oxide (NO) in vivo by gas-phase chemiluminescence assay

There are several methods utilized for detection of nitric oxide (NO) and its various metabolites in biological systems. These include spectrophotometric analysis, high performance liquid chromatography, mass spectrophotometry, electro-paramagnetic resonance (EPR), and gas-phase chemiluminscence. Of these, the gas-phase chemiluminescence technique is perhaps the most sensitive, with a limit of detection in the femtomole range. Furthermore, as there are a number of commercially available NO analyzers, it is possible to directly compare results from different laboratories using this technique. Described in this unit is a group-specific derivatization approach with gas-phase chemiluminscence detection to profile NO metabolites in vivo.

Monitoring the health to disease continuum with global metabolic profiling and systems biology

Global metabolic profiling, which includes both metabolomics and metabonomics studies, is the latest ‘omics’ research platform that is being applied to understand the health and disease continuum. Metabolic profiling analyses have been demonstrated for the investigation of inborn errors of metabolism, organ transplant rejection, drug toxicity, disease diagnosis and prognosis, drug efficacy and nutritional status. Combining information generated from a metabolic profiling platform with that obtained based on genetics, transcriptomics and proteomics research paradigms will pave the way for a better understanding of the mechanisms of disease and toxicity. Metabolomics and nutrition will lay the groundwork for the application of personalized medicine in the 21st century.

Synthesis and anti-inflammatory activity of a series of N-substituted naproxen glycolamides: nitric oxide-donor naproxen prodrugs

A series of glycolamide naproxen prodrugs containing a nitrate group as a nitric oxide (NO) donor moiety has been synthesized. These compounds were evaluated for their anti-inflammatory activity, naproxen release, and gastric tolerance. Compounds 4a, 4b, 5a, 5b, 7b, and 7c exhibited anti-inflammatory activity equivalent to that of the parent NSAID, naproxen-Na, in the rat carrageenan paw edema model. At equimolar doses relative to naproxen-Na, the NO-donor glycolamide derivatives 4a, 4b, 5a, 5b, 7b, and 7c were gastro-sparing in the rat. Naproxen formation from these NO-donor glycolamides varied among the structures examined, with the N-substituent on the amide group having a particular influence, and demonstrated their prodrug nature. Compound 7b was selected for exemplary demonstration that the glycolamide nitrates can be bioactivated to release NO. These data open the possibility that naproxen glycolamide nitrates may represent a safer alternative to naproxen as anti-inflammatory medicines.