Synthesis,Molecular Docking,and Biological Evaluation of Some Novel Hydrazones and Pyrazole Derivatives as Anti‐inflammatory Agents

2‐Hydrazinyl‐N‐(4‐sulfamoylphenyl)acetamide 3 was the key intermediate for the synthesis of novel hydrazones 4–10 and pyrazole derivatives 11–17 . All compounds were tested for their in vivo anti‐inflammatory activity and their ability to inhibit the production of PGE₂ in serum samples of rats. IC₅₀ values for the most active compounds for inhibition of COX‐1 and COX‐2 enzymes were determined in vitro, and they were also tested for their ulcerogenic effect. Molecular docking was performed on the active site of COX‐2 to predict their mode of binding to the amino acids. Most of the synthesized compounds showed good anti‐inflammatory activity especially compounds 3, 4, 8, 9, 15, and 17 which showed better activity than diclofenac as the reference drug. Compounds 3, 8, 9, 13, and 15–17 were less ulcerogenic than indomethacine as the reference drug. Most of the synthesized compounds interacted with Tyr 385 and Ser 530 in molecular docking study with additional hydrogen bond for compound 17 . Compound 17 showed good selectivity index value of 11.1 for COX‐1/COX‐2 inhibition in vitro.     

New pyrazole derivative 5‐[1‐(4‐fluorophenyl)‐1H‐pyrazol‐4‐yl]‐2H‐tetrazole: synthesis and assessment of some biological activities

The molecular modification and synthesis of compounds is vital to discovering drugs with desirable pharmacological and toxicity profiles. In response to pyrazole compounds' antipyretic, analgesic, and anti‐inflammatory effects, this study sought to evaluate the analgesic, anti‐inflammatory, and vasorelaxant effects, as well as the mechanisms of action, of a new pyrazole derivative, 5‐[1‐(4‐fluorophenyl)‐1H‐pyrazol‐4‐yl]‐2H‐tetrazole. During the acetic acid‐induced abdominal writhing test, treatments with 5‐[1‐(4‐fluorophenyl)‐1H‐pyrazol‐4‐yl]‐2H‐tetrazole reduced abdominal writhing, while during the formalin test, 5‐[1‐(4‐fluorophenyl)‐1H‐pyrazol‐4‐yl]‐2H‐tetrazole reduced licking times in response to both neurogenic pain and inflammatory pain, all without demonstrating any antinociceptive effects, as revealed during the tail flick test. 5‐[1‐(4‐fluorophenyl)‐1H‐pyrazol‐4‐yl]‐2H‐tetrazole also reduced carrageenan‐induced paw edema and cell migration during the carrageenan‐induced pleurisy test. As demonstrated by the model of the isolated organ, 5‐[1‐(4‐fluorophenyl)‐1H‐pyrazol‐4‐yl]‐2H‐tetrazole exhibits a vasorelaxant effect attenuated by Nω‐nitro‐l ‐arginine methyl ester, 1H‐[1,2,4]oxadiazolo[4,3‐alpha]quinoxalin‐1‐one, tetraethylammonium or glibenclamide. 5‐[1‐(4‐fluorophenyl)‐1H‐pyrazol‐4‐yl]‐2H‐tetrazole also blocked CaCl₂‐induced contraction in a dose‐dependent manner. Suggesting a safe toxicity profile, 5‐[1‐(4‐fluorophenyl)‐1H‐pyrazol‐4‐yl]‐2H‐tetrazole reduced the viability of 3T3 cells at higher concentrations and was orally tolerated, despite signs of toxicity in doses of 2000 mg/kg. Lastly, the compounds' analgesic activity might be attributed to the involvement of the NO/cGMP pathway and K⁺ channels observed in the vasorelaxant effect.     

Discovery of Novel 2‐(piperidin‐4‐yl)‐1H‐benzo[d]imidazole Derivatives as Potential Anti‐Inflammatory Agents

A novel 2‐(piperidin‐4‐yl)‐1H‐benzo[d]imidazole derivative 5 with good anti‐inflammatory activity was identified from our in‐house library. Based on hit compound 5 , two series of 2‐(piperidin‐4‐yl)‐1H‐benzo[d]imidazole derivative 6a – g and 7a – h were designed and synthesized as novel anti‐inflammatory agents. Most of synthesized compounds exhibited good inhibitory activity on NO and TNF‐α production in LPS‐stimulated RAW 264.7 macrophages, in which the compound 6e showed most potent inhibitory activity on NO (IC₅₀ = 0.86 μm ) and TNF‐α (IC₅₀ = 1.87 μm ) production. Further evaluation revealed that compound 6e displayed more potent in vivo anti‐inflammatory activity than ibuprofen did on xylene‐induced ear oedema in mice. Additionally, Western blot analysis revealed that compound 6e could restore phosphorylation level of IκBα and protein expression of p65 NF‐κB in LPS‐stimulated RAW 264.7 macrophages.     

Synthesis and pharmacological evaluation of 3‐(4‐chloro phenyl)‐2‐substituted‐3H‐quinazolin‐4‐ones as analgesic and anti‐inflammatory agents

A new series of 3‐(4‐chloro phenyl)‐2‐substituted‐3H‐quinazolin‐4‐ones were synthesized by reacting the amino group of 2‐hydrazino‐3‐(4‐chloro phenyl)‐3H‐quinazolin‐4‐one with different aldehydes and ketones. The compounds were investigated for their analgesic activity in albino mice, and for their anti‐inflammatory and ulcerogenic activities in Wistar rats. All test compounds exhibited analgesic and anti‐inflammatory activities. Compound VA2 (2‐(1‐ethylpropylidene‐hydrazino)‐3‐(4‐chloro phenyl)‐3H‐quinazolin‐4‐one) showed moderately more potent analgesic activity and compound VA3 (2‐(1‐methylbutylidene‐hydrazino)‐3‐(4‐chlorophenyl)‐3H‐quinazolin‐4‐one) showed moderately more potent anti‐inflammatory activity when compared with the reference standard, diclofenac sodium. The test compounds showed only mild ulcerogenic side effects when compared with aspirin. Drug Dev Res 69: 226–233, 2008 ©2008 Wiley‐Liss, Inc.     

Synthesis,molecular docking,and pharmacological evaluation of N‐(2‐(3,5‐dimethoxyphenyl)benzoxazole‐5‐yl)benzamide derivatives as selective COX‐2 inhibitors and anti‐inflammatory agents

A series of N‐(2‐(3,5‐dimethoxyphenyl)benzoxazole‐5‐yl)benzamide derivatives ( 3am ) was synthesized and evaluated for their in vitro inhibitory activity against COX‐1 and COX‐2. The compounds with considerable in vitro activity (IC₅₀ < 1 μM) were evaluated in vivo for their anti‐inflammatory potential by the carrageenan‐induced rat paw edema method. Out of 13 newly synthesized compounds, 3a , 3b , 3d , 3g , 3j , and 3k were found to be the most potent COX‐2 inhibitors in the in vitro enzymatic assay, with IC₅₀ values in the range of 0.06–0.71 μM. The in vivo anti‐inflammatory activity of these six compounds ( 3a , 3b , 3d , 3g , 3j , and 3k ) was assessed by the carrageenan‐induced rat paw edema method. Compounds 3d (84.09%), 3g (79.54%), and 3a (70.45%) demonstrated significant anti‐inflammatory activity compared to the standard drug ibuprofen (65.90%) and were also found to be safer than ibuprofen, by ulcerogenic studies. A docking study was done using the crystal structure of human COX‐2, to understand the binding mechanism of these inhibitors to the active site of COX‐2.

     

1‐[(2,3‐Dihydro‐1‐benzofuran‐2‐yl) methyl]piperazines as novel anti‐inflammatory compounds: Synthesis and evaluation on H3R/H4R

The histamine receptors (HRs) are members of G‐protein‐coupled receptor superfamily and traditional targets of huge therapeutic interests. Recently, H₃R and H₄R have been explored as targets for drug discovery, including in the search for dual‐acting H₃R/H₄R ligands. The H₄R, the most recent histamine receptor, is a promising target for novel anti‐inflammatory agents in several conditions such as asthma and other chronic inflammatory diseases. Due to similarity with previously reported ligands of HRs, a set of 1‐[(2,3‐dihydro‐1‐benzofuran‐2‐yl)methyl]piperazines were synthesized and evaluated in competitive binding assays as H₃R/H₄R ligands herein. The results showed the compounds presented affinity (K_i) for H₃R/H₄R in micromolar range, and they are more selective to H₃R. All the compounds showed no important cytotoxicity to mammalian cells. The phenyl‐substituted compound LINS01005 has shown the higher affinity of the set for H₄R, but no considerable selectivity toward this receptor over H₃R. LINS01005 showed interesting anti‐inflammatory activity in murine asthma model, reducing the eosinophil counts in bronchoalveolar lavage fluid, as well as the COX‐2 expression. The presented compounds are valuable prototypes for further improvements to achieve better anti‐inflammatory agents.     

Synthesis,analgesic, anti‐inflammatory and ulcerogenic index activities of novel 2‐methylthio‐3‐substituted‐5,6‐dimethyl thieno [2,3‐d] pyrimidin‐4(3H)‐ones

A variety of novel 2‐methylthio‐3‐substituted amino‐5,6‐dimethyl thieno [2,3‐d] pyrimidin‐4(3H)‐ones were synthesized by reacting 3‐amino‐2‐methylthio‐5,6‐dimethyl thieno [2,3‐d] pyrimidin‐4(3H)‐one with different aldehydes and ketones. The starting material 3‐amino‐2‐methylthio‐5,6‐dimethyl thieno [2,3‐d] pyrimidin‐4(3H)‐one was synthesized from 2‐amino‐3‐carbethoxy‐4,5‐dimethyl thiophene. The compounds were investigated for their analgesic activity in albino mice, and for their anti‐inflammatory and ulcerogenic index activities in Wistar rats. The compound 2‐(1‐ethylpropylideneamino)‐2‐methylthio‐5,6‐dimethyl thieno [2,3‐d] pyrimidin‐4(3H)‐one (AS2) showed the most potent analgesic activity of the series. It also showed more potent anti‐inflammatory activity when compared to the reference standard, diclofenac sodium. The test compounds showed only mild ulcerogenic potential when compared to aspirin. Drug Dev Res 68:134–142, 2007. © 2007 Wiley‐Liss, Inc.     

Inhibition of key enzymes in the inflammatory pathway by hybrid molecules of terpenes and synthetic drugs: In vitro and in silico studies

The aim of this work was to compare the anti‐inflammatory activity of compounds prepared from terpenes and the synthetic drugs ibuprofen and naproxen. The anti‐inflammatory activity of the hybrid compounds was compared with the activity of the parent compounds. This was accomplished using in vitro inhibition of lipoxygenases (LOX) and COX‐2, and in silico docking studies in 15‐LOX and COX‐2. The synthesized hybrids showed an inhibition of COX‐2 and LOX between 9.8%–57.4% and 0.0%–97.7%, respectively. None of the hybrids showed an improvement in the inhibitory effect toward these pro‐inflammatory enzymes, compared to the parent terpenes and non‐steroidal anti‐inflammatory drugs. The docking studies allowed us to predict the potential binding modes of hybrids 6 – 15 within COX‐2 and 15‐LOX active sites. The relative affinity of the compounds inside the binding sites could be explained by forming non‐covalent interactions with most important and known amino acids reported for those enzymes. A good correlation (r² = 0.745) between docking energies and inhibition percentages against COX‐2 was found. The high inhibition obtained for compound 10 against COX‐2 was explained by hydrogen bond interactions at the enzyme binding site. New synthetic possibilities could be obtained from our in silico models, improving the potency of these hybrid compounds.     

Effectiveness of Novel 5‐(5‐amino‐1‐aryl‐1H‐pyrazol‐4‐yl)‐1H‐tetrazole Derivatives Against Promastigotes and Amastigotes of Leishmania amazonensis

In this research, a series of substituted 5‐(5‐amino‐1‐aryl‐1H‐pyrazol‐4‐yl)‐1H‐tetrazoles were synthesized and evaluated for in vitro antileishmanial activity. Among the derivatives, examined compounds 3b and 3l exhibited promising activity against promastigotes and amastigotes forms of Leishmania amazonensis. The cytotoxicity of these compounds was evaluated on murine cells, giving access to the corresponding selectivity index (SI).     

Synthesis and Antibacterial Activity of a New Series of 3‐[3‐(Substituted Phenyl)‐1‐Isonicotinoyl‐1H‐Pyrazol‐5‐yl]‐2H‐Chromen‐2‐one Derivatives

A novel series of 3‐[3‐(substituted phenyl)‐1‐isonicotinoyl‐1H‐pyrazol‐5‐yl]‐2H‐chromen‐2‐one derivatives 4a – k have been synthesized by the reaction of 3‐[2,3‐dibromo‐3‐(substituted phenyl) propanoyl]‐2H‐chromen‐2‐one 3a – k and isonicotinic acid hydrazide in the presence of triethylamine in absolute ethanol, characterized by spectral data and screened for their in‐vitro antibacterial activity against Gram‐positive and Gram‐negative bacteria. Among the series, compounds 4e , 4i , and 4k displayed an encouraging antibacterial activity profile as compared to the reference drug ampicillin against tested bacterial strains.     

3‐(3‐Ethylphenyl)‐2‐substituted hydrazino‐3H‐quinazolin‐4‐one Derivatives: New Class of Analgesic and Anti‐Inflammatory Agents

A new series of 3‐(3‐ethylphenyl)‐2‐substituted hydrazino‐3H‐quinazolin‐4‐ones were synthesized by reacting the amino group of 2‐hydrazino‐3‐(3‐ethylphenyl)‐3H‐quinazolin‐4‐one with a variety of aldehydes and ketones. The title compounds were investigated for analgesic, anti‐inflammatory and ulcerogenic index behavior. The compound 2‐(N′‐3‐pentylidene‐hydrazino)‐3‐(3‐ethylphenyl)‐3H‐quinazolin‐4‐one ( AS2 ) emerged as the most active compound in exhibiting analgesic activity and the compound 2‐(N′‐2‐pentylidene‐hydrazino)‐3‐(3‐ethylphenyl)‐3H‐quinazolin‐4‐one ( AS3 ) emerged as the most active compound in exhibiting anti‐inflammatory activity; and these compounds are moderately potent when compared with the reference standard diclofenac sodium. Interestingly, the test compounds showed only mild ulcerogenic potential when compared with aspirin.     

Novel 3,6‐Disubstituted 7H‐1,2,4‐Triazolo[3,4‐b][1,3,4]thiadiazines: Synthesis,Characterization, and Evaluation of Analgesic / Anti‐inflammatory,Antioxidant Activities

In this study, the synthesis of a new series of 3,6‐disubstituted‐7H‐1,2,4‐triazolo[3,4‐b][1,3,4]thiadiazine 1a – 4c compounds derived from 4‐amino‐3‐substituted‐1,2,4‐triazole‐5‐thiones 1 – 4 is described. All of the synthesized compounds were screened for their possible analgesic / anti‐inflammatory, antioxidant activities and gastric toxicity. The compound 2c was found to have both significant analgesic and consistent anti‐inflammatory activity without inducing any gastric lesions along with minimal lipid peroxidation. A deep insight into the structures of the active compounds revealed that the compounds carrying an electron withdrawing group (a chloride or fluoride) on the phenyl ring at 6‐position of the condensed heterocyclic derivatives exhibited noticeable higher activity.     

Design and Synthesis of 2‐Phenoxynicotinic Acid Hydrazides as Anti‐inflammatory and Analgesic Agents

A series of 2‐phenoxynicotinic acid hydrazides were synthesized and evaluated for their analgesic and anti‐inflammatory activities. Several compounds having an unsubstituted phenyl/4‐pyridyl or C‐4 methoxy substituent on the terminal phenyl ring showed moderate to high analgesic or anti‐inflammatory activity in comparison to mefenamic acid as the reference drug. The compounds with highest anti‐inflammatory activity were subjected to in vitro COX‐1/COX‐2 inhibition assays and showed moderate to good COX‐1 and weak COX‐2 inhibition activities.     

Synthesis and Structure‐Activity Relationship Studies of Pyrazole‐based Heterocycles as Antitumor Agents

Several 4‐cyano‐1,5‐diphenylpyrazoles attached to different heterocyclic ring systems at position 3 were synthesized starting from ethyl 4‐cyano‐1,5‐diphenyl‐1H‐pyrazole‐3‐carboxylate 1 . The newly synthesized compounds were tested in vivo for their anti‐estrogenic effects and evaluated in vitro for their cytotoxic properties against estrogen‐dependent tumors. 3‐(5‐Mercapto‐1,3,4‐oxadiazole‐2‐yl)‐1,5‐diphenyl‐1H‐pyrazole‐4‐carbonitrile 13 revealed the highest cytotoxic activity with a GI₅₀ value equal to 40 nM against the IGROVI ovarian tumor cell line. It also showed an anti‐estrogen activity 1.6 more effective than the reference drug, in addition to a high tolerable dose. 3‐(5‐(Methylthio)‐4‐phenyl‐4H‐1,2,4‐triazol‐3‐yl)‐1,5‐diphenyl‐1H‐pyrazole‐4‐carbonitrile 7 was found to have the highest anti‐estrogenic activity, while 1,5‐diphenyl‐3‐[5‐(phenylamino)‐1,3,4‐thiadiazol‐2‐yl]‐1H‐pyrazole‐4‐carbonitrile 11 showed the lowest activity. The oral LD₅₀ values revealed that most of the tested compounds are relatively nontoxic.     

Synthesis of New 2,3‐Dihydroquinazolin‐4(1H)‐one Derivatives for Analgesic and Anti‐inflammatory Evaluation

Starting from isatoic anhydrides, several new 2,3‐dihydroquinazolin‐4(1H)‐one derivatives bearing chalcone or pyrazole or thiazole moieties at the third position were synthesized. The analgesic and anti‐inflammatory activities for most compounds were studied at a dose level of 50 mg/kg via the acetic‐acid‐induced writhing‐response method and carrageenan‐induced edema method, respectively. The study showed that the chalcones bearing a 4‐chlorophenyl group 4c or 4‐nitrophenyl group 4b were the most active ones as analgesics. Both chalcone 4c and N‐phenyl pyrazole bearing 4‐methoxy phenyl group 5b showed a higher anti‐inflammatory activity than celecoxib but still lower than that of diclofenac sodium. Moreover, the chalcone 4c has nearly the same ulcerogenic index as the selective cyclooxygenase‐2 inhibitor celecoxib.     

Design,Synthesis, Biological Evaluation,and Docking Study of Acetylcholinesterase Inhibitors: New Acridone‐1,2,4‐oxadiazole‐1,2,3‐triazole Hybrids

In this study, novel acridone‐1,2,4‐oxadiazole‐1,2,3‐triazole hybrids were designed, synthesized, and evaluated for their acetylcholinesterase and butyrylcholinesterase inhibitory activity. Among various synthesized compounds, 10‐((1‐((3‐(4‐methoxyphenyl)‐1,2,4‐oxadiazol‐5‐yl)methyl)‐1H‐1,2,3‐triazol‐4‐yl)methyl)acridin‐9(10H)‐one 10b showed the most potent anti‐acetylcholinesterase activity (IC₅₀ = 11.55 μm ) being as potent as rivastigmine. Also docking outcomes were in good agreement with in vitro results confirming the dual binding inhibitory activity of compound 10b .     

Synthesis of new pyrazolo[3,4‐d]pyrimidine derivatives and evaluation of their anti‐inflammatory and anticancer activities

This study reports the synthesis of two series of new purine bioisosteres comprising a pyrazolo[3,4‐d]pyrimidine scaffold linked to piperazine moiety through different amide linkages. The newly synthesized compounds were evaluated for anticancer activity against four cell lines (MDA‐MB‐231, MCF‐7, SF‐268, B16F‐10) and cyclooxygenase (COX‐2) protein expression inhibition in lipopolysaccharide (LPS)‐activated rat monocytes. The results revealed that most of the synthesized compounds showed moderate‐to‐high cytotoxic activity against at least one cell line, with compound 10b being the most active against all used cell lines (IC₅₀ values 5.5–11 μg/ml) comparable to cisplatin. In addition, six of these compounds ( 7b, 10a–d, and 12c ) demonstrated inhibition of LPS‐induced COX‐2 protein expression at low concentration (25 μg/ml) as compared to the control non‐stimulated cells and showed a COX‐2 selectivity index range comparable to diclofenac sodium. The overall results indicate that many of these pyrazolopyrimidine derivatives possess in vitro anti‐inflammatory and anticancer activities at varying doses, and the most active compounds will be subjected to in vivo pharmacological evaluation.     

Design and synthesis of pyrazole–pyrazoline hybrids as cancer‐associated selective COX‐2 inhibitors

In continuation of our previous work on cancer and inflammation, 15 novel pyrazole–pyrazoline hybrids ( WSPP1 – 15 ) were synthesized and fully characterized. The formation of the pyrazoline ring was confirmed by the appearance of three doublets of doublets in ¹H nuclear magnetic resonance spectra exhibiting an AMX pattern for three protons (H_A, H_M, and H_X) of the pyrazoline ring. All the synthesized compounds were screened for their in vitro anticancer activity against five cell lines, that is, MCF‐7, A549, SiHa, COLO205, and HepG2 cells, using the MTT growth inhibition assay. 5‐Fluorouracil was taken as the positive control in the study. It was observed that, among them, WSPP11 was found to be active against A549, SiHa, COLO205, and HepG2 cells, with IC₅₀ values of 4.94, 4.54, 4.86, and 2.09 µM. All the derivatives were also evaluated for their cytotoxicity against HaCaT cells. WSPP11 was also found to be nontoxic against normal cells (cell line HaCaT), with an IC₅₀ value of more than 50 µM. The derivatives were also evaluated for their in vitro anti‐inflammatory activity by the protein (egg albumin) denaturation assay and the red blood cell membrane stabilizing assay, using diclofenac sodium and celecoxib as standard. Compounds that showed significant anticancer and anti‐inflammatory activities were further studied for COX‐2 inhibition. The manifestation of a higher COX‐2 selectivity index of WSPP11 as compared with other derivatives and an in vitro anticancer activity against four cell lines further established that compounds that were more selective toward COX‐2 also exhibited a better spectrum of activity against various cancer cell lines.     

Synthesis,Molecular Modeling,and Biological Evaluation of Novel 1, 3‐Diphenyl‐2‐propen‐1‐one Based Pyrazolines as Anti‐inflammatory Agents

A novel series of 1,3‐diphenyl‐2‐propen‐1‐one (chalcone) derivatives was synthesized by a simple, eco‐friendly, and efficient Claisen–Schmidt condensation reaction and used as precursors for the synthesis of new pyrazoline derivatives. All the synthesized compounds were screened for anti‐inflammatory related activities such as inhibition of phospholipase A₂ (PLA₂), cyclooxygenases (COX‐1 and COX‐2), IL‐6, and TNF‐α. The results of the above studies show that the compounds synthesized are effective inhibitors of above pro‐inflammatory enzymes and cytokines. Overall, the results of the studies reveal that the pyrazolines with chlorophenyl substitution ( 1b – 6b ) seem to be important for inhibition of enzymes and cytokines. Molecular docking experiments were performed to clarify the molecular aspects of the observed COX‐inhibitory activities of the investigated compounds.     

Synthesis and Biological Evaluation of 4‐Arylphthalazones Bearing Benzenesulfonamide as Anti‐Inflammatory and Anti‐Cancer Agents

Nine 4‐arylphthalazones bearing benzenesulfonamide (2a – i ) were synthesized by the condensation of the appropriate 2‐aroylbenzoic acid ( 1a – i ) and 4‐hydrazinobenzenesulfonamide in ethanol. The structures of these compounds were elucidated by elemental analysis, IR, ¹H NMR, ¹³C NMR, and MS spectroscopy. Two compounds, 2b and 2i , showed significant anti‐inflammatory activity comparable to that of the standard drug celecoxib in the carrageenan‐induced rat paw edema model. These compounds ( 2b and 2i ) had selective inhibitory activity towards the COX‐2 enzyme. Compound 2b had a better selectivity ratio (COX‐1/COX‐2) compared to that of celecoxib and can be used as a novel template for the design of selective COX‐2 inhibitors. Compounds 2d and 2i were screened for their antiproliferative activity toward 60 human cancer cell lines by the National Cancer Institute (USA). The compounds 2d and 2i displayed mild activity toward the renal cancer cell line UO‐31.