Studies on antiinflammatory agents. I. Synthesis and pharmacological properties of 2'-phenoxymethanesulfonanilide derivatives

Direct C-H Sulfuration: Synthesis of Disulfides, Dithiocarbamates, Xanthates, Thiocarbamates and Thiocarbonates

In light of the important biological activities and widespread applications of organic disulfides, dithiocarbamates, xanthates, thiocarbamates and thiocarbonates, the continual persuit of efficient methods for their synthesis remains crucial. Traditionally, the preparation of such compounds heavily relied on intricate multi-step syntheses and the use of highly prefunctionalized starting materials. Over the past two decades, the direct sulfuration of C-H bonds has evolved into a straightforward, atom- and step-economical method for the preparation of organosulfur compounds. This review aims to provide an up-to-date discussion on direct C-H disulfuration, dithiocarbamation, xanthylation, thiocarbamation and thiocarbonation, with a special focus on describing scopes and mechanistic aspects. Moreover, the synthetic limitations and applications of some of these methodologies, along with the key unsolved challenges to be addressed in the future are also discussed. The majority of examples covered in this review are accomplished via metal-free, photochemical or electrochemical approaches, which are in alignment with the overraching objectives of green and sustainable chemistry. This comprehensive review aims to consolidate recent advancements, providing valuable insights into the dynamic landscape of efficient and sustainable synthetic strategies for these crucial classes of organosulfur compounds.

A novel three-component reaction between isocyanides, alcohols or thiols and elemental sulfur: a mild, catalyst-free approach towards O-thiocarbamates and dithiocarbamates

A new multicomponent reaction has been developed between isocyanides, sulfur and alcohols or thiols under mild reaction conditions to afford O-thiocarbamates and dithiocarbamates in moderate to good yields. The one-pot reaction cascade involves the formation of an isothiocyanate intermediate, thus a catalyst-free synthesis of isothiocyanates, as valuable building blocks from isocyanides and sulfur is proposed, as well. The synthetic procedure suits the demand of a modern organic chemist, as it tolerates a wide range of functional groups, it is atom economic and easily scalable.

Nimesulide analogues: From anti-inflammatory to antitumor agents

Nimesulide is a nonsteroidal anti-inflammatory drug possessing analgesic and antipyretic properties. This drug is considered a selective cyclooxygenase-2 (COX-2) inhibitor and, more recently, has been associated to antitumor activity. Thus, numerous works have been developed to modify the nimesulide skeleton aiming to develop new and more potent and selective COX-2 inhibitors as well as potential anticancer agents. This review intends to provide an overview on analogues of nimesulide, including the general synthetic approaches used for their preparation and structural diversification and their main anti-inflammatory and/or antitumor properties.

Synthesis of N-[2-(2,4-Difluorophenoxy)trifluoromethyl-3-pyridyl]sulfonamides and their inhibitory activities against secretory phospholipase A₂

N-[2-(2,4-Difluorophenoxy)trifluoromethyl-3-pyridyl]sulfonamide derivatives 3-6 were prepared by the reaction of 3-pyridylamines and sulfonyl chlorides. Inhibitory activities of these compounds toward secretory phospholipase A₂ (sPLA₂) were examined and N-[2-(2,4-difluorophenoxy)-5-trifluoromethyl-3-pyridyl]-2-naphthalenesulfonamide (5c) was found to be the most potent against sPLA₂ with an IC₅₀ value of 90 µM.

New fluoro derivatives of the pyrazolo[5,1-c][1,2,4]benzotriazine 5-oxide system: evaluation of fluorine binding properties in the benzodiazepine site on γ-aminobutyrric acid type A (GABA(A)) receptor. Design, synthesis, biological, and molecular modeling investigation

In the search for potent ligands at the benzodiazepine site on the GABA(A) receptor, new fluoro derivatives of the pyrazolo[5,1-c][1,2,4]benzotriazine system were synthesized to evaluate the importance of the introduction of a fluorine atom in this system. Biological and pharmacological studies indicate that the substitution at position 8 with a trifluoromethyl group confers pharmacological activity due to potential metabolic stability in comparison to inactive 8-methyl substituted analogues. In particular, the compound 3-(2-methoxybenzyloxycarbonyl)-8-trifluoromethylpyrazolo[5,1-c][1,2,4]benzotriazine 5-oxide (21) emerges because of its selective anxiolytic profile without side effects. An analysis of all the newly synthesized compounds in our pharmacophoric map confirms the essential interaction points for binding recognition and the important areas for affinity modulation. The fluorine atom was able to form a hydrogen bond interaction only when it is not in position 3.

The effects of cyclooxygenase (COX)-2 inhibition on ischemia-reperfusion injury in liver transplantation

PURPOSE

Our objective was to evaluate whether COX-2 inhibition with FK3311, a selective cyclooxygenase (COX)-2 inhibitor, improves transplanted liver function.

METHODS

Inbred male Lewis rats weighing 200-260 g were used. The donor liver was perfused with cold University of Wisconsin (UW) solution and then stored in the same solution at 4 degrees C for 18 hr. After the preservation period, orthotopic liver transplantation was performed. Animals were divided into three groups: the control group; the FK low-dose group (1 mg/kg FK3311 i.v. 20 min before reperfusion); and the FK high-dose group (3 mg/kg FK3311 i.v. 20 min before reperfusion). Survival rate, serum GOT and GPT levels, liver tissue blood flow, and serum thromboxane B(2) (TxB(2)) levels were compared among groups.

RESULTS

Survival rate was significantly better (p <. 05) and serum GOT levels 30 min after reperfusion were significantly lower (p <. 05) in the FK high-dose group compared to the other two groups. Four hours after reperfusion, GPT levels and liver tissue flow were significantly (p <. 05) better in the FK high-dose group compared to the control. Both 30 min and 4 hr after reperfusion, serum TxB(2) levels were significantly lower in the FK high-dose group compared to the control (p <. 05).

CONCLUSION

COX-2 activity results in deteriorated liver function after I/R injury associated with transplantation, and selective COX-2 inhibition improved liver graft function.

Inhibition of Cyclooxygenase-2 Improves Cardiac Function Following Long-Term Preservation

BACKGROUND

Cyclooxygenase (COX) is an intracellular enzyme that converts arachidonic acid to prostaglandin endoperoxide (PGG(2)). There are two isoforms of COX, namely constitutive COX-1 and inducible COX-2. It has been reported that COX-2 plays an important role in ischemia-reperfusion injury and that COX-2 mRNA and protein expression were up-regulated during cardiac allograft rejection. FK3311 is a suppressor of COX-2 activation. The purpose of this study was to evaluate the effectiveness of inhibiting COX-2 with FK3311 for the minimization of ischemia-reperfusion injury and for the improvement of donor heart function following transplantation in a canine model.

MATERIALS AND METHODS

Adult mongrel dogs were used. After the measurement of hemodynamic parameters [cardiac output (CO), left ventricular pressure (LVP), and the maximum rates of increase and decrease in LVP (+/-LVdp/dt)], coronary vascular beds were washed out with a hypothermic (4 degrees C) University of Wisconsin (UW) solution following cardiac arrest in response to cold (4 degrees C) glucose-insulin-potassium solution. The heart was then excised and preserved in hypothermic (4 degrees C) UW solution for 12 h. FK3311 (3 mg/kg) was administered intravenously to five dogs prior to reperfusion, while vehicle was administered intravenously to a control group (n = 5). After 3 h of orthotopic transplantation using cardiopulmonary bypass, the hemodynamic parameters were compared with preoperative values of the donor animals under the condition of 10 mm Hg right atrial pressure and 5 mug/kg/min dopamine support.

RESULTS

The recovery rates of CO and +/-LVdP/dt were significantly (P < 0.05) higher in the FK-treated dogs than in the controls (CO: 93 +/- 6 versus 66% +/- 4%; +LVdp/dt: 125 +/- 8 versus 77 +/- 10%; and -LVdp/dt: 81 +/- 7 versus 52 +/- 6%; for FK-treated versus control dogs, respectively). The recovery rate of LVP was higher in the FK-treated dogs than in the controls (90 +/- 5 versus 72 +/- 5%), but this difference was not statistically significant. Immunohistochemical staining revealed that COX-2 expression was reduced significantly in the myocardium of FK-treated dogs compared with controls.

CONCLUSION

Hemodynamic parameters following transplantation were improved significantly in dogs treated with FK3311. Therefore, the inhibition of COX-2 improves transplanted cardiac function following long-term preservation.

8,9-dihydroxy-1,2,3,11b-tetrahydrochromeno[4,3,2,-de]isoquinoline (dinoxyline), a high affinity and potent agonist at all dopamine receptor isoforms

The synthesis and preliminary pharmacological evaluation of 8,9-dihydroxy-1,2,3,11b-tetrahydrochromeno[4,3,2,-de]isoquinoline (5, now named dinoxyline) is described. This molecule was designed as a potential bioisostere that would conserve the essential elements of our beta-phenyldopamine D(1) pharmacophore (i.e., position and orientation of the nitrogen, hydroxyls, and phenyl rings). Previously, we have rigidified these elements using alkyl bridges, as exemplified in the dopamine D(1) full agonist molecules dihydrexidine (1) and dinapsoline (2). This approach has been modified and we now show that it is possible to tether these elements using an ether linkage. Preliminary pharmacology has revealed that 5 is a potent full D(1) agonist (K(0.5) <10 nM; EC(50)=30 nM), but also has high affinity for brain D(2)-like and cloned D(2) and D(3) receptors. Interestingly, whereas 1 and 2 and their analogues have only moderate affinity for the human D(4) receptor, 5 also has high affinity for this isoform. Moreover, although N-alkylation of 1 and 2 increases D(2) affinity, the N-allyl (15) and N-n-propyl (17) derivatives of 5 had decreased D(2) affinity. Therefore, 5 may be engaging different amino acid residues than do 1 and 2 when they bind to the D(2) receptor. This is the first example of a ligand with high affinity at all dopamine receptors, yet with functional characteristics similar to dopamine. These rigid ligands also will be useful tools to determine specific residues of the receptor transmembrane domains that are critical for agonist ligand selectivity for the D(4) receptor.

Synthesis of some new 2-substituted-phenyl-1H-benzimidazole-5-carbonitriles and their potent activity against Candida species

New 2-substituted-phenyl-1H-benzimidazole-5-carboxylic acids (35, 38), ethyl-5-carboxylate (36), -5-carboxamides (37, 39),-5-carboxaldehyde (42), -5-chloro (40), -5-trifluoromethyl (41), and -5-carbonitriles (44-53, 55-67), -6-carbonitrile (54) were prepared and evaluated in vitro against Candida species. The cyano substituted compounds 53, 57, 58 and 61 exhibited the greatest activity with MIC values of 3.12 microg/mL, values similar to that of fluconazole.

The effect of a selective cyclooxygenase-2 inhibitor in extended liver resection with ischemia in dogs

BACKGROUND

Pringle's procedure is commonly used during liver surgery, and it sometimes causes liver failure. Metabolites of arachidonic acid, which are converted by cyclooxygenase (Cox), are involved in ischemia-reperfusion injury. This study evaluated the effects of FK 3311, which selectively inhibits Cox-2, on ischemia-reperfusion injury during liver resection in dogs.

MATERIALS AND METHODS

The animals were divided into four groups and subjected to 60 min of warm ischemia by partial inflow occlusion. The FK-treated groups (FK0.2: 0.2 mg/kg, FK1: 1 mg/kg, FK3: 3mg/kg) received FK3311, and the control group received vehicle. Following reperfusion, the nonischemic lobes were resected and remnant liver function was evaluated.

RESULTS

Tissue blood flow and serum glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, and lactate dehydrogenase were significantly better in the FK1 and FK3 groups, especially FK1, than in the control group. Thromboxane B(2) was significantly lower in the FK1 and FK3 groups than in the control group. The level of 6-keto-prostaglandin F(1alpha) was significantly lower in the FK3 group and relatively unchanged in the FK1 group. Histological damage was milder in the FK1 group. There were significantly fewer polymorphonuclear neutrophils in the FK1 group than in the control group.

CONCLUSIONS

FK3311 ameliorates the ischemia-reperfusion injury caused by Pringle's procedure during extensive liver resection. This agent may be clinically useful in extended liver surgery involving vascular isolation.

The anti-inflammatory effect of FR188582, a highly selective inhibitor of cyclooxygenase-2, with an ulcerogenic sparing effect in rats

The anti-inflammatory and ulcerogenic effects of FR188582, 3-chloro-5-[4-(methylsulfonyl) phenyl]-1-phenyl-1H-pyrazole, were investigated. In a recombinant human cyclooxygenase (COX) enzyme activity, FR188582 inhibited COX-2 with an IC50 value of 0.017 microM, and the inhibition of prostaglandin (PG) E2 formation by FR188582 was over 6000 times more selective for COX-2 than COX-1. Oral administration of FR188582 dose-dependently inhibited adjuvant arthritis. This effect was threefold more potent than that of indomethacin. FR188582 and indomethacin dose-dependently suppressed the formation of immunoreactive PGE2, but not immunoreactive leukotriene (LT) B4, in arthritic paw. Unlike indomethacin, FR188582 did not induce visible gastric lesions in rats at doses up to 32 mg/kg, p.o. Furthermore, FR188582 did not inhibit the level of immunoreactive PGE2 and immunoreactive 6-keto PGF1alpha in rat gastric mucosa. These results suggest that FR188582, a highly selective COX-2 inhibitor, has a potent anti-inflammatory effect mediated by inhibition of PGE2 in inflamed tissues. The safety profile of FR188582 appears to be improved over the safety profile of indomethacin.

Substituted heterocyclic analogs as selective COX-2 inhibitors in the flosulide class

Substituted heterocyclic analogs in the Flosulide class were investigated as potential selective cyclooxygenase-2 inhibitors. 6-(4-Ethyl-2-thiazolylthio)-5-methanesulfonamido-3H-isobe nzofuran-1-one 14 was found to be the optimal compound in the series with superior in vitro and in vivo activities.

Cyclooxygenase-2 inhibitors in tumorigenesis (part I)

The rate-limiting enzyme in arachidonate metabolism is mediated by enzymes known as cyclooxygenases (COXs). These enzymes catalyze the biosynthesis of prostaglandin H2, the precursor of molecules, such as prostaglandins, prostacyclin, and thromboxanes. The COX enzyme family consists of the classical COX-1 enzyme, which is constitutively expressed in many tissues, and a second enzyme, i.e., COX-2, which is induced by various stimuli, such as mitogens and cytokines, and is involved in many inflammatory reactions. Because nonsteroidal anti-inflammatory drugs inhibit both COX-1 and COX-2, these drugs also cause unwanted side effects, exemplified by gastrointestinal bleeding. Accumulating evidence indicates that nonsteroidal anti-inflammatory drugs can reduce the incidence of colorectal cancers in human and experimental animals and can reduce the polyp number and size in patients with familial adenomatous polyposis. This Part I (of a two-part review) focuses on the discovery of the COXs; their biochemical, molecular, and structural properties; and on the discovery of isozyme-specific inhibitors of COX activity.

Discovery of FR115092: a novel antinephritic agent

A series of dapsone-related 4-aminopheynl and 2-aminothiazolyl derivatives was prepared, and their antinephritic activity and blood toxicity were evaluated. 5-(2-Pyridylsulfonyl)-2-thiazolamine (FR115092, 26) was effective against two nephritis models, namely graft-versus-host disease (GVHD) and autoimmune W/BF1 mice, and showed none of the blood toxicity observed with dapsone.

Inhibition of constitutive and inducible cyclooxygenase activity in human platelets and mononuclear cells by NSAIDs and Cox 2 inhibitors

A range of NSAIDs and reported Cox 2 selective compounds were tested in human freshly isolated platelets and LPS-stimulated mononuclear cells to determine their potency and selectivity as inhibitors of constitutive (presumably Cox 1) and inducible (presumably Cox 2) cyclooxygenase respectively. All compounds tested were either equipotent at inhibiting constitutive and inducible cyclooxygenase or were selective for the inducible form. The most selective compound was Dup697 and the least selective, ketoprofen. Several compounds only produced a partial inhibition of constitutive cyclooxygenase as the maximum inhibitor concentration achievable in the assay was limited to 1 mM. With the exception of paracetamol, all compounds were able to produce full inhibition curves against the inducible form. Potency estimates against constitutive Cox compare closely with published data but most compounds were consistently more potent against the inducible isoform than in published data for human cloned, microsomal Cox 2. These data suggest that human mononuclear cells are either exquisitely sensitive to some NSAIDs or they may contain another Cox isoform as yet indistinguishable from Cox 2.