Synthesis and biological evaluation of some 4-functionalized-pyrazoles as antimicrobial agents

Environmentally Friendly Synthesis of New Mono- and Bis-Pyrazole Derivatives; In Vitro Antimicrobial, Antifungal, and Antioxidant Activity; and In Silico Studies: DFT, ADMETox, and Molecular Docking

Background/Objectives: Antimicrobial resistance and oxidative stress are major global health challenges, necessitating the development of novel therapeutic agents. Pyrazole derivatives, known for their diverse pharmacological properties, hold promise in addressing these issues. This study aimed to synthesize new mono- and bis-pyrazole derivatives using an eco-friendly, catalyst-free approach and evaluate their antioxidant, antibacterial, and antifungal activities, supported by in silico ADMET profiling, molecular docking, and Density Functional Theory (DFT) analysis. Methods: The compounds were synthesized via a green condensation reaction and characterized using NMR and mass spectrometry, which was verified by DFT analysis. Biological activities were assessed through DPPH and FRAP antioxidant assays, as well as disk diffusion and MIC methods, against bacterial strains (Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli) and fungal strains (Candida albicans and Aspergillus niger). Computational ADMET profiling evaluated pharmacokinetics and toxicity, while molecular docking assessed interactions with target proteins, including catalase, topoisomerase IV, and CYP51. Results: Theoretical calculations using DFT were in agreement with the experimental results; regarding biological activities, O4 demonstrated the most significant antioxidant activity, with 80.14% DPPH radical scavenging and an IC50 value of 40.91 µg/mL. It exhibited potent antimicrobial activity, surpassing Streptomycin with a 30 mm inhibition zone against Pseudomonas aeruginosa and showing strong efficacy against Staphylococcus aureus and Candida albicans. Computational studies confirmed favorable pharmacokinetic properties, no AMES toxicity, and strong binding affinities. DFT analysis revealed O4's stability and reactivity, further validating its potential as a therapeutic candidate. Conclusions: This study identified and characterized novel pyrazole derivatives with promising biological and pharmacological properties. O4 emerged as the most potent compound, demonstrating strong antioxidant and antimicrobial activities alongside favorable computational profiles. These findings highlight the potential of the synthetized compounds for therapeutic development and underscore the value of integrating green synthesis with computational techniques in drug discovery.

Synthesis, Spectroscopic Characterization, Structural Analysis, and Evaluation of Anti-Tumor, Antimicrobial, and Antibiofilm Activities of Halogenoaminopyrazoles Derivatives

New haloaminopyrazole derivatives differing in the number of pyrazole nuclei 4a-f and 5a-e, respectively, were synthesized and characterized by 1H-NMR, 13C-NMR, IR, UV-Vis, and elemental analysis. The single-crystal X-ray diffraction method was used to describe compounds 4a and 5d. When tested on normal NCTC fibroblasts in vitro, the newly synthesized derivatives were shown to be non-cytotoxic at a dosage of 25 μg/mL. Two compounds 4a and 5d showed a high degree of biocompatibility. From the two series of compounds tested on HEp-2 human cervical carcinoma cells, compound 5d showed a more pronounced antiproliferative effect. Gram-positive strains of Staphylococcus aureus ATCC25923, Enterococcus faecalis ATCC29212, Gram-negative strains of Pseudomonas aeruginosa ATCC27853, and strains of Escherichia coli ATCC25922 were used to test the newly synthesized compounds antibacterial and antibiofilm properties. Among the studied pyrazole compounds, 2 compounds 4a and 5a with fluorine content on the phenyl ring and 4 compounds 4b, 4e, 4f, and 5b with chlorine content on the phenyl ring were noted, which proved to be the most active compared with the two reference drugs, metronidazole and nitrofurantoin. The six compounds showed a broad spectrum of action against all four tested bacterial strains, the most active being compound 4b, with a chlorine atom in the "4" position of the phenyl nucleus and a MIC of 460 μg/mL. Compounds 4a and 5a showed the best antibiofilm activity against the bacterial strain Staphylococcus aureus ATCC25923, with an MBIC of 230 μg/mL.

Insight on novel sulfamoylphenyl pyrazole derivatives as anticancer carbonic anhydrase inhibitors

As another part continue for our previous study, variable substituted pyrazoles bearing sulfamoylphenyl moiety were synthesized and screened against two cancer related human carbonic anhydrase (hCA) isoforms and acetazolamide (AAZ) used as a reference standard. Some compounds as 4e and 6c manifested a promising inhibitory activity against both isoforms (KI = 0.072, 0.081 and 0.073, 0.095 µM), respectively. While others as 4a and 5e showed inhibitory activity against hCA IX only (KI = 0.062, 0.04 µM) or against hCA XII only as compound 5b (KI = 0.106 µM) compared to AAZ (KI = 0.065, 0.046 µM), respectively. Also, the anticancer efficacy against 60 cancer cell lines for the target compounds was assessed, and the most promising ones were 4d and 5a-d. Further investigation of the anticancer activity of 5b on MCF-7 cell line explored (IC50 = 5.21 µM) compared to doxorubicin (IC50 = 11.58 µM). Moreover, compound 5b was exposed to cell cycle analysis and apoptotic assay on MCF-7 breast cancer cell line under both normal and hypoxic conditions at its IC50 concentration with elevation of total apoptotic cells % in MCF-7 relative to the control cells; respectively. Finally, molecular modelling simulations rationalized the in vitro testing results.

Synthesis of N-Sulfonyl Formamidines by Direct Condensation between Sulfonamide and Formamide Enabled by a Photogenerated Vilsmeier-Type Reagent

Herein, we report the synthesis of N-sulfonyl formamidines from carbon tetrabromide and formamide under UVA irradiation without any additional catalysts. This approach represents a straightforward methodology for accessing this class of structural units and has been applied to a wide range of readily available sulfonamides and formamides, providing the corresponding products in moderate to excellent yields (30 examples, 16-99% yields). Mechanistic investigations associated with previous reports suggest the implication of an activated iminium intermediate (Vilsmeier-Haack reagent derivatives), obtained by the photoinduced reaction between carbon tetrabromide and formamides.

Synthesis, docking and characterization of some novel 5-(S-alkyl)-1.3.4-thiadiazole-2-carboxamide derivatives as anti-inflammatory and antibacterial agents

Because of the great pharmacological and industrial significance of 1,3,4-thiadiazole and its related compounds, researchers are still very interested in them. For this reason, in this study, we looked at ways to create new hybrid compounds containing carboxamide and 1,3,4-thiadiazole moieties. The thioxoacetamide derivatives used to make these compounds were reacted with various alkylated reagents to produce multiple S-alkyl groups. Additionally, these compounds were reacted with aldehydes to form novel derivatives known as 5-(substituent)-N-phenyl-1,3,4-thiadiazole-2-carboxamide. Here, we used the agar well diffusion method to examine the antibacterial activity of all the produced compounds against a few pathogenic bacteria that were resistant to multiple drugs. Additionally, look into their capacity to lower inflammation through the use of bovine serum albumin in the protein denaturation procedure. The substances were characterized by spectral analysis (IR, 1HNMR, 13CNMR and Elemental Analysis), and efficient as antibacterial agents against all the tested bacterial strains, except for Escherichia coli. Compounds 4a and 8c showed the highest level of inhibition zone against Gram-positive bacteria (Staph. aureus, Bacillus subtilis) at concentration 0.3, 0.4 and 0.5 mg/ml compared with ciprofloxacin at the same concentrations. The results demonstrated that every compound has significant anti-inflammatory activity. At a concentration of 250 µg/ml, compounds 3a, 4c and 8c had the highest percentage inhibition of protein denaturation when (83.24%, 86.44% and 85.14%, respectively) compared to other compounds and diclofenac sodium as reference drug. Comparing compounds 4c and 8c to ciprofloxacin and diclofenac sodium, they showed powerful antibacterial and anti-inflammatory action. Furthermore, an investigation using molecular docking against DHPS from S. aureus (PDB ID: 6CLV) showed a strong connection with the intended protein and an elevated docking score, making it a prime candidate for antibiotics.

Exploring novel anticancer pyrazole benzenesulfonamides featuring tail approach strategy as carbonic anhydrase inhibitors

This study aimed to design potent carbonic anhydrase inhibitors (CAIs) based on pyrazole benzenesulfonamide core. Nine series of substituted pyrazole benzenesulfonamide compounds were synthesized with variable groups like sulphamoyl group as in compounds 4a-e, its bioisosteric carboxylic acid as in compounds 5a-e and 8e, ethyl carboxylate ester as in compounds 6a-e and 9a-e, which were designed as potential prodrugs, isothiazole ring as in compound 7, hydrazide derivative 10e, hydroxamic acid derivatives 11a-e and semicarbazide derivatives 12a-c,e. All the synthesized compounds were investigated for their carbonic anhydrase (CA) inhibitory activity against two human CA isoforms hCA IX and hCA XII and compared to acetazolamide (AAZ). Also, the compounds were assessed for their anticancer activity against 60 cancer cell lines according to the US NCI protocol. Compounds 4b, 5b, 5d, 5e, 6b, 9b, 9e and 11b revealed significant inhibitory activity against both isoforms hCA IX and hCA XII, while 6e, 9d, 11d and 11e showed significant inhibitory activity against hCA XII only compared to acetazolamide as a reference. This would highlight these compounds as promising anticancer drugs. Moreover, compound 6e revealed a remarkable cytostatic activity against CNS cancer cell line (SF-539; TGI = 5.58 μM), renal cancer cell line (786-0; TGI = 4.32 μM) and breast cancer cell line (HS 578 T; TGI = 5.43 μM). Accordingly, compound 6e was subjected to cell cycle analysis and apoptotic assay on the abovementioned cell lines at the specified GI50 (0.45, 0.89 and 1.18 μM, respectively). Also, it revealed the increment of total apoptotic cells percentage in 786-0 (53.19%), SF-539 (46.11%) and HS 578 T (43.55%) relative to the control cells (2.07, 2.64 and 2.52%, respectively). In silico prediction of BBB permeability showed that most of the calculations for compound 6e resulted as BBB (+), which is required for a compound targeting CNS. Further, the interaction of the most active compounds with the key amino acids in the active sites of hCA IX and hCA XII was highlighted by molecular docking analysis.

New Pyrazole-Clubbed Pyrimidine or Pyrazoline Hybrids as Anti-Methicillin-Resistant Staphylococcus aureus Agents: Design, Synthesis, In Vitro and In Vivo Evaluation, and Molecular Modeling Simulation

Two hybrid series of pyrazole-clubbed pyrimidines 5a-c and pyrazole-clubbed pyrazoline compounds 6a,b and 7 were designed as attractive scaffolds to be investigated in vitro and in vivo for antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. From the results of the in vitro antibacterial screening, compound 5c showed excellent activity (minimal inhibitory concentration, MIC = 521 μM) when compared with that of the reference antibiotic levofloxacin (MIC = 346 μM). The inhibition of the target dihydrofolate reductase (DHFR) enzyme by compounds 4 and 5a-c (IC50 = 5.00 ± 0.23, 4.20 ± 0.20, 4.10 ± 0.19, and 4.00 ± 0.18 μM, respectively) was found to be better than the reference drug trimethoprim (IC50 = 5.54 ± 0.28 μM). Molecular modeling simulation results have justified the order of activity of all the newly synthesized compounds as DHFR enzyme inhibitors, and compound 5c exhibited the best binding profile (-13.6169386 kcal/mol). Hence, the most potent inhibitor of the DHFR enzyme, 5c, was chosen to be evaluated in vivo for its activity in treating MRSA-induced keratitis in rats and that, in turn, significantly (P < 0.0001) reduced infection in rats when compared to MRSA-treated group results.

Synthesis, antimicrobial and antioxidant activity of triazole, pyrazole containing thiazole derivatives and molecular docking studies on COVID-19

New series of biologically active triazole and pyrazole compounds containing 2, 4-disubstituted thiazole analogues (12a-l) were synthesized from p-hydroxy benzaldehyde and phenyl hydrazine in excellent yields and purity. All the synthesized compounds were unambiguously identified based on their spectral data analyses (IR, ¹H-NMR, ¹³C-NMR spectra, and HRMS). The final derivatives were evaluated for their in vitro anti-microbial activity after thorough purification. Among all the tested compounds, the compound 12e, 12f and 12 k possess the highest growth inhibitory activity at MIC values of 4.8, 5.1 and 4.0 μg/ml respectively. The antioxidant properties of these compounds demonstrated and revealed remarkable activity compared to the standard antioxidant by using the DPPH free radical-scavenging assay. Moreover, molecular docking studies to evaluate the probable interactions with the catalytic domain of the gram-positive S. aureus topoisomerase IV enzyme may provide new insights for developing these new hybrids as potential antimicrobial agents. The binding affinities of compounds 12a-l were ranging from - 10.0 to - 11.0 kcal/mol with topoisomerase IV enzyme and with COVID-19 main protease binding affinities are ranging from - 8.2 to - 9.3 kcal/mol. These docking studies reveal that the compounds 12a-l could be the best inhibitors for the novel SARS Cov-2 virus and have more future in discovery of potent drug candidates.

Crystallographic study, biological assessment and POM/Docking studies of pyrazoles-sulfonamide hybrids (PSH): Identification of a combined Antibacterial/Antiviral pharmacophore sites leading to in-silico screening the anti-Covid-19 activity

The discovery and development of new potent antimicrobial and antioxidant agents is an essential lever to protect living beings against pathogenic microorganisms and free radicals. In this regard, new functionalized pyrazoles have been synthesized using a simple and accessible approach. The synthesized aminobenzoylpyrazoles 3a-h and pyrazole-sulfonamides 4a-g were obtained in good yields and were evaluated in vitro for their antimicrobial and antioxidant activities. The structures of the synthesized compounds were determined using IR, NMR, and mass spectrometry. The structure of the compound 4b was further confirmed by single crystal X-ray diffraction. The results of the in vitro screening show that the synthesized pyrazoles 3 and 4 exhibit a promising antimicrobial and antioxidant activities. Among the tested compounds, pyrazoles 3a, 3f, 4e, 4f, and 4g have exhibited remarkable antimicrobial activity against some microorganisms. In addition, compounds 3a, 3c, 3e, 4a, 4d, 4f, and 4g have shown a significant antioxidant activity in comparison with the standard butylhydroxytoluene (BHT). Hence, compounds 3a, 4f, and 4g represent interesting dual acting antimicrobial and antioxidant agents. In fact, pyrazole derivatives bearing sulfonamide moiety (4a-g) have displayed an important antimicrobial activity compared to pyrazoles 3a-h, this finding could be attributed to the synergistic effect of the pyrazole and sulfonamide pharmacophores. Furthermore, Molecular docking results revealed a good interaction of the synthesized compounds with the target proteins and provided important information about their interaction modes with the target enzyme. The results of the POM bioinformatics investigations (Petra, Osiris, Molinspiration) show that the studied heterocycles present a very good non toxicity profile, an excellent bioavailability, and pharmacokinetics. Finally, an antiviral pharmacophore (O δ-, O δ-) was evaluated in the POM investigations and deserves all our attention to be tested against Covid-19 and its Omicron and Delta mutants.

A Molecular Insight into Pyrazole Congeners as Antimicrobial, Anticancer, and Antimalarial Agents

BACKGROUND

Pyrazole is a bioactive heterocyclic congener found in a wide range of biological and pharmacological applications. Due to their multiple prospective uses, developing innovative pyrazoles and analogues, disclosing revolutionary ways for synthesizing this nucleus, investigating diverse potencies of that heterocycle, and seeking for possible applications of pyrazoles are all growing more significant Objectives: Pyrazole scaffolds have been proven to be successful as antimicrobial, anticancer, antimalarial therapeutic against multiple targets like DNA gyrase, topoisomerase IV, Hsp90, and several kinase enzymes. Its moiety has absorbed the attention of many scientists to research chemical and pharmacological profile due to this miscellany in the biotic region.

RESULTS

The review covers pyrazole scaffolds with a variety of biological functions, as well as attempts to connect the structure-activity relationship. Multiple pyrazole analogues have been produced as lead compounds, and their activities have been evaluated.

CONCLUSION

The combination of pyrazole with other pharmacophores in a molecule might lead to novel potent therapeutic medicines, which could aid in the development of potent lead compounds.

Novel benzenesulfonamide-bearing pyrazoles and 1,2,4-thiadiazoles as selective carbonic anhydrase inhibitors

Two series comprising 20 novel benzenesulfonamides bearing thioureido-linked pyrazole 8 and amino-1,2,4-thiadiazole 10 were synthesized and assayed as human carbonic anhydrase (hCA) inhibitors against isoforms I and II as well as the tumor-associated isoforms IX and XII. Molecular modeling studies of some potent derivatives (8a, 8c, 10a, and 10c) were also performed against isoforms hCA I, II, and XII. Both the promising series of compounds were synthesized by using commercially available mtethyl ketones and sulfanilamide as the starting materials. Interestingly, this paper also reports a novel methodology for the synthesis of amino-1,2,4-thiadiazoles 10 using 3-amino isoxazoles and 4-isothiocyanatobenzenesulfonamide as reactants. The activity profile of all the newly synthesized compounds reveals that amino-linked 1,2,4-thiadiazoles 10 were better inhibitors of the cytosolic isoform, hCA I, as compared to thioureido-linked pyrazoles 8. Further, hCA II was strongly inhibited by nearly all the newly synthesized sulfonamides, while all the compounds were less effective as hCA IX and XII inhibitors compared to the standard drug acetazolamide. However, in terms of selectivity, compound 8e was found to be the most selective inhibitor of hCA II, which is the isoform associated with glaucoma, edema, altitude sickness, and epilepsy.

Design, synthesis and mechanistic study of novel diarylpyrazole derivatives as anti-inflammatory agents with reduced cardiovascular side effects

Novel diarylpyrazole (5a-d, 6a-e, 12, 13, 14, 15a-c and 11a-g) derivatives were designed, synthesized and evaluated for their dual COX-2/sEH inhibitory activities via recombinant enzyme assays to explore their anti-inflammatory activities and cardiovascular safety profiles. Comprehensively, the structures of the synthesized compounds were established via spectral and elemental analyses, followed by the assessment of both their in vitro COX inhibitory and in vivo anti-inflammatory activities. The most active compounds as COX inhibitors were further evaluated for their in vitro 5-LOX and sEH inhibitory activities, alongside with their in vivo analgesic and ulcerogenic effects. Compounds 6d and 11f showed excellent inhibitory activities against both COX-2 and sEH (COX-2 IC₅₀ = 0.043 and 0.048 µM; sEH IC₅₀ = 83.58 and 83.52 μM, respectively). Moreover, the compounds demonstrated promising results as anti-inflammatory and analgesic agents with considerable ED₅₀ values and gastric safety profiles. Remarkably, the most active COX inhibitors 6d and 11f possessed improved cardiovascular safety profiles, if compared to celecoxib, as shown by the laboratory evaluation of both essential cardiac biochemical parameters (troponin-1, prostacyclin, tumor necrosis factor-α, lactate dehydrogenase, reduced glutathione and creatine kinase-M) and histopathological studies. On the other hand, docking simulations confirmed that the newly synthesized compounds displayed sufficient structural features required for binding to the target COX-2 and sEH enzymes. Also, in silico ADME studies prediction and drug-like properties of the compounds revealed favorable oral bioavailability results. Collectively, the present work could be featured as a promising future approach towards novel selective COX-2 inhibitors with declined cardiovascular risks.

Pyrazole-Thiazole Core-Containing Analogs Exhibit Adjunctive Activity with Meropenem against Carbapenem-Resistant Enterobacteriaceae (CRE)

Pyrazole-thiazole core-containing compound KP-40 and 20 novel derivatives were designed and synthesized through traditional SAR analysis. These molecules displayed adjunctive activity with meropenem against Gram-negative bacteria evidenced by a range of fractional inhibitory concentration (FIC=0.5-0.25) and minimum adjunctive concentration (MAC=128-32 μM) values. Of this series of molecules, four compounds displayed notable adjunctive potential, with FIC and MAC values of 0.25 and 32 μM, respectively. Moreover, the solubility of these compounds was improved to an acceptable range. Further analysis using our "in house" permeation and efflux multi parameter optimization (PEMPO) algorithm revealed key physicochemical properties that may be critical for the development of active Gram-negative antibacterials. Taking PEMPO scores into consideration prior to executing synthesis of analogs may be a simple, yet rapid and effective strategy that can be used in conjunction with traditional SAR approaches to aid in the design of potent Gram-negative antibacterials.

Design, Synthesis and Pharmacological Evalution of 1,3,4-Oxadiazole Derivatives as Collapsin Response Mediator Protein 1 (CRMP 1) Inhibitors

OBJECTIVE

The series of 2-(4-Phenylamino)-N-(5-((4-nitrophenoxy)methyl) -1,3,4-oxadiazol- 2-yl)aceta-mide (5a-5e) and substituted N-(5-(Phenoxymethyl)-1,3,4-oxadiazol-2-yl)-2- (phenylamino)acetamide (5f-5i) was designed, synthesized and investigated for Collapsin Response Mediator Protein 1 (CRMP 1) inhibitors as small lung cancer.

DESIGN

Design of compounds was determined by literature review and molecular docking studies in iGEMDOCK 2.0.

MATERIALS AND METHODS

Novel 1, 3, 4 Oxadiazole derivatives were synthesized and characterized by melting point, TLC, IR Spectroscopy, Mass spectroscopy and 1H NMR. In vitro biological evaluation was performed on NCI-H2066 cell line for different concentrations 10-1000μM by telomeric repeat amplification protocol assay. The assay of telomerase in cellular extracts was modified from the PCR-based Telomeric-Repeat Amplification Protocol (TRAP), using the oligonucleotides TS and CX.

RESULTS

Novel substituted 2-(4-Phenylamino)-N-(5-((4-nitrophenoxy)methyl)-1,3,4-oxadiazol-2- yl) acetamide (5a-5e) and substituted N-(5-(Phenoxymethyl)-1,3,4-oxadiazol-2-yl)-2-(phenylamino) acetamide (5f-5i) were synthesized, and characterized using spectral and analytical data. All compounds have shown considerable % inhibition of Cell Growth with respect to Bevacizumab, but compound 5a and 5f were equipotent with respect to activity as compared to standard Bevacizumab.

CONCLUSION

Amongst the hybrids, p-nitro substituted derivative (5a) and p-chloro substituted (5f) showed the highest activity against human lung cancer cell line NCI-H2066 by TRAP assay.

Synthesis of novel pyrazole tagged pyridine derivatives; their antimicrobial activity

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Novel pyrazole tagged pyridine derivatives 5a-n synthesized starting from 3-cyano-4-trifluoromethyl-6- thiophenyl 2(1H) pyridone 1. Compound 1 on hydrolysis followed by decarboxylation resulted in 4-trifluoro-methyl-6- thiophenyl 2(1H)pyridone 2. Compound 2 treated with POCl3 to get 2- chloro-4-trifluoromethyl-6- thiophenyl pyridine 3 further reaction with hydrazine hydrate, which resulted in the formation of compound 4. Compound 4 on reaction with different substituted 1,3-diketones in ethanol reflux condition to afford pyrazole substituted pyridine derivatives 5a-n. All derivatives were tested against Gram-positive and Gram-negative bacterial strains and different Candida strains by well diffusion method, compounds 5k and 5l showed significant activity. The binding mode of 5k and 5l also studied by molecular docking studies.

Fused pyrazole-phenanthridine based dyads: synthesis, photo-physical and theoretical studies, and live cell pH imaging

The arrangement of small sized molecules with a scaffold structure plays an active role in the fields of sensors and health care. An efficient molecular design strategy for four pyrazole-phenanthridine based D-π-A luminophores, denoted as 2a, 2b, 2c and 2d was developed to investigate the effect of acid on the photo-physical properties of these dyes. Photo-physical studies of the synthesized probes showed distinct absorption and emission under various pH conditions. Theoretical calculations using density functional methods were carried out for understanding the mechanistic aspects of the proton induced fluorescence. The experimentally observed photo-physical properties correlated well with theoretical results. Moreover, probes 2 and 2a can be used to monitor the fluorescence changes in E. coli cells under different pH conditions.

Sustainable Synthetic Approach for (Pyrazol-4-ylidene)pyridines By Metal Catalyst-Free Aerobic C(sp2)-C(sp3) Coupling Reactions between 1-Amino-2-imino-pyridines and 1-Aryl-5-pyrazolones

A novel, metal catalyst-free, and efficient method has been developed for the synthesis of (pyrazol-4-ylidene)pyridine derivatives. The process involves dehydrogenative coupling of 1-amino-2-imino-pyridines with 1-aryl-5-pyrazolone derivatives utilizing O2 as the sole oxidant. The new method benefits from a high atom economy, efficiency, and substrate scope, as well as the simplicity of reaction and product purification procedures.

Novel synthesis of new pyrazole thioglycosides as pyrazomycin analogues

This study reports a novel method for the synthesis of a new class of pyrazole thioglycosides 7a-h as pyrazomycin analogues. These series of compounds were designed through the reaction of sodium 2-cyano-3-oxo-3-(4-substitutedphenylamino)prop-1-ene-1,1-bis(thiolate) salts 2 with phenyl hydrazine in ethanol at room temperature to give the corresponding sodium 5-amino-4-(substitutedphenylcarbamoyl)-1-phenyl-1H-pyrazole-3-thiolates 3a-d. The latter compounds were treated with tetra-acetylated glycosyl bromides 4a,b in DMF at ambient temperature to give the corresponding pyrazole thioglycosides 6a-h. Treatment of pyrazole salts 3a-d with hydrochloric acid at room temperature afforded the corresponding 3-mercaptopyrazole derivatives 5. The latter compounds were treated with tetra-acetylated glycosyl bromides 4 in sodium hydride-DMF to tolerate the S-glycosyl 6a-h compounds. Ammonolysis of the latters afforded the corresponding free thioglycosides 7a-h. The structures of the reaction products were elucidated based on spectral data and elemental analysis.

A new efficient domino approach for the synthesis of coumarin-pyrazolines as antimicrobial agents targeting bacteriald-alanine-d-alanine ligase

The inhibition ofd-alanine-d-alanine ligase (Ddl) prevents bacterial growth, which makes this enzyme an attractive and viable target in the urgent search for novel effective antimicrobial drugs.

Microwave-assisted synthesis, computational studies and antibacterial/ anti-inflammatory activities of compounds based on coumarin-pyrazole hybrid

An efficient, high-yield and rapid synthesis of (E)-1,5-dimethyl-4-((2-((substituted-2-oxo-2H-chromen-4-yl)methoxy)naphthalen-1-yl)methyleneamino)-2-phenyl-1,2-dihydropyrazol-3-one derivatives (3a-3i) containing Schiff base structures under microwave-irradiation has been described. Schiff base is a potential target to discover anti-inflammatory chemotherapeutics, material science, catalysis and molecular magnetism. All the newly synthesized compounds (3a-3i) have been characterized by elemental analysis and spectroscopic techniques. The synthesized compounds (3a-3i) were evaluated for their antibacterial activity by agar-well diffusion method and anti-inflammatory activity by egg albumin denaturation method. The compounds (3e) and (3i) exhibit antibacterial effect with minimum inhibitory concentration (MIC) 0.78 µg ml^-1 and MIC 1.562 µg ml^-1 against Gram-positive Staphylococcus aureus bacterial strain compared with standard ciprofloxacin drug (MIC 6.25 µg ml^-1). The compounds (3c) and (3f) exhibited an inhibition of heat-induced protein denaturation at the concentration (31.25 µg ml^-1) as 53.65% and 67.27%, respectively, and these compounds are more active than standard aceclofenac drug (5.50%). Molecular docking study has been performed for all the synthesized compounds with S. aureus dihydropteroate synthetase and results obtained are quite promising.

Synthesis and Pharmacological Activities of Pyrazole Derivatives: A Review

Pyrazole and its derivatives are considered a pharmacologically important active scaffold that possesses almost all types of pharmacological activities. The presence of this nucleus in pharmacological agents of diverse therapeutic categories such as celecoxib, a potent anti-inflammatory, the antipsychotic CDPPB, the anti-obesity drug rimonabant, difenamizole, an analgesic, betazole, a H2-receptor agonist and the antidepressant agent fezolamide have proved the pharmacological potential of the pyrazole moiety. Owing to this diversity in the biological field, this nucleus has attracted the attention of many researchers to study its skeleton chemically and biologically. This review highlights the different synthesis methods and the pharmacological properties of pyrazole derivatives. Studies on the synthesis and biological activity of pyrazole derivatives developed by many scientists around the globe are reported.

Synthesis and Pharmacological Activities of Pyrazole Derivatives: A Review

Pyrazole and its derivatives are considered a pharmacologically important active scaffold that possesses almost all types of pharmacological activities. The presence of this nucleus in pharmacological agents of diverse therapeutic categories such as celecoxib, a potent anti-inflammatory, the antipsychotic CDPPB, the anti-obesity drug rimonabant, difenamizole, an analgesic, betazole, a H2-receptor agonist and the antidepressant agent fezolamide have proved the pharmacological potential of the pyrazole moiety. Owing to this diversity in the biological field, this nucleus has attracted the attention of many researchers to study its skeleton chemically and biologically. This review highlights the different synthesis methods and the pharmacological properties of pyrazole derivatives. Studies on the synthesis and biological activity of pyrazole derivatives developed by many scientists around the globe are reported.

Synthesis of Oxadiazolyl, Pyrazolyl and Thiazolyl Derivatives of Thiophene-2-Carboxamide as Antimicrobial and Anti-HCV Agents

Introduction:

Three series of pyrazole, thiazole and 1,3,4-oxadiazole, derivatives were synthesized starting from 5-amino-4-(hydrazinocarbonyl)-3-methylthiophene-2-carboxamide (2).

Methods:

All compounds were investigated for their preliminary antimicrobial activity. They were proved to exhibit remarkable antimicrobial activity against Pseudomonas aeruginosa with insignificant activity towards Gram positive bacterial strains and fungi.

Results:

In-vitro testing of the new compounds on hepatitis-C virus (HCV) replication in hepatocellular carcinoma cell line HepG2 infected with the virus utilizing the reverse transcription polymerase chain reaction technique (RT-PCR) generally showed inhibition of the replication of HCV RNA (–) strands at low concentration, while, eight compounds; 3a, 6, 7a, 7b, 9a, 9b, 10a and 11b proved to inhibit the replication of HCV RNA (+) and (–) strands at very low concentration range 0.08-0.36 μg/mL.

Conclusion:

Compounds 7b and 11b displayed the highest anti-HCV and antimicrobial activities in this study.

Synthesis of 4-(2-substituted hydrazinyl)benzenesulfonamides and their carbonic anhydrase inhibitory effects

In this study, 4-(2-substituted hydrazinyl)benzenesulfonamides were synthesized by microwave irradiation and their chemical structures were confirmed by (1)H NMR, (13)CNMR, and HRMS. Ketones used were: Acetophenone (S1), 4-methylacetophenone (S2), 4-chloroacetophenone (S3), 4-fluoroacetophenone (S4), 4-bromoacetophenone (S5), 4-methoxyacetophenone (S6), 4-nitroacetophenone (S7), 2-acetylthiophene (S8), 2-acetylfuran (S9), 1-indanone (S10), 2-indanone (S11). The compounds S9, S10 and S11 were reported for the first time, while S1-S8 was synthesized by different method than literature reported using microwave irradiation method instead of conventional heating in this study. The inhibitory effects of 4-(2-substituted hydrazinyl)benzenesulfonamide derivatives (S1-S11) against hCA I and II were studied. Cytosolic hCA I and II isoenzymes were potently inhibited by new synthesized sulphonamide derivatives with Kis in the range of 1.79 ± 0.22-2.73 ± 0.08 nM against hCA I and in the range of 1.72 ± 0.58-11.64 ± 5.21 nM against hCA II, respectively.

Pyrazolylbenzo[d]imidazoles as new potent and selective inhibitors of carbonic anhydrase isoforms hCA IX and XII

Novel pyrazolylbenzo[d]imidazole derivatives (2a-2f) were designed, synthesized and evaluated against four human carbonic anhydrase isoforms belonging to α family comprising of two cytosolic isoforms hCA I and II as well as two transmembrane tumor associated isoforms hCA IX and XII. Starting from these derivatives that showed high potency but low selectivity in favor of tumor associated isoforms hCA IX and XII, we investigated the impact of removing the sulfonamide group. Thus, analogs 3a-3f without sulfonamide moiety were synthesized and biological assay revealed a good activity as well as an excellent selectivity as inhibitors for tumor associated hCA IX and hCA XII and the same was analyzed by molecular docking studies.

4-Functionalized 1,3-diarylpyrazoles bearing benzenesulfonamide moiety as selective potent inhibitors of the tumor associated carbonic anhydrase isoforms IX and XII

A library of 4-functionalized 1,3-diarylpyrazoles (3a-3h, 5a-5g and 6a-6g) was designed, synthesized and evaluated against four human carbonic anhydrase (CA, EC 4.2.1.1) isozymes representing two cytosolic isozymes hCA I and hCA II, and two transmembrane tumor associated ones, hCA IX and hCA XII. All the twenty two tested compounds exhibited excellent CA activity profile against the four CA isozymes when compared to the reference drug acetazolamide. Six of the tested compounds (3a-3b, 3f, 3h, 6a and 6b) displayed low nanomolar affinity (Ki < 5 nM) for hCA IX whereas seven compounds (3a-3b, 3d-3f, 3h and 6f) displayed Ki < 10 nM against hCA XII. In addition, they acted as selective CA inhibitors of isoforms IX and XII over the physiological isoforms I and II.

Ferrocenylpyrazolyl palladium complexes as catalysts for the polymerisation of 1-heptene and 1-octene to highly branched polyolefins

(Ferrocenylpyrazolyl)palladium complexes that catalyse the polymerization of 1-heptene and 1-octene to highly branched polyolefins are reported.

Identification of a series of 1,3,4-trisubstituted pyrazoles as novel hepatitis C virus entry inhibitors

In this report we describe the identification of novel pyrazole analogs as potent hepatitis C virus (HCV) entry inhibitor. The pyrazoles were identified by our phenotypic high-throughput screening using infectious HCV. A series of pyrazole derivatives was synthesized and evaluated for inhibitory activity against HCV in the infectious cell culture system. Through evaluation of selected compounds we observed that the pyrazoles did not interfere with HCV RNA replication but with viral entry as shown by experiments with HCV replicons and HCV pseudo particles, respectively.

Synthesis of some novel 4-arylidene pyrazoles as potential antimicrobial agents

BACKGROUND

Pyrazole and pyrazolone motifs are well known for their wide range of biological activities such as antimicrobial, anti-inflammatory, and antitumor activities. The incorporation of more than one pharmacophore in a single scaffold is a well known approach for the development of more potent drugs. In the present investigation, a series of differently substituted 4-arylidene pyrazole derivatives bearing pyrazole and pyrazolone pharmacophores in a single scaffold was synthesized.

RESULTS

The synthesis of novel 4-arylidene pyrazole compounds is achieved through Knovenagel condensation between 1,3-diaryl-4-formylpyrazoles and 3-methyl-1-phenyl-1H-pyrazol-5-(4H)-ones in good yields. All compounds were evaluated for their in vitro antimicrobial activity.

CONCLUSIONS

A series of 4-arylidene pyrazole derivatives was evaluated for their in vitro antimicrobial activity against two Gram-positive (Bacillus subtilis and Staphylococcus aureus) and two Gram-negative bacteria (Pseudomonas fluorescens and Escherichia coli), as well as two pathogenic fungal strains (Candida albicans and Saccharomyces cerevisiae). The majority of the compounds displayed excellent antimicrobial profile against the Gram-positive (B. subtilis and S. aureus), and some of them are even more potent than the reference drug ciprofloxacin.

Demonic axe-like conjugated alkynes in combating microbes

A new series of disubstituted alkynes was obtained by microwave induced internal splitting of the corresponding β-oxo-alkylidenetriphenylphosphoranes. The antimicrobial potential of these conjugated alkynes and phosphoranes was assayed in vitro against three Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, Staphylococcus epidermidis), three Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae) and five fungal strains (Aspergillus niger, Candida albicans, Aspergillus flavus, Candida rugosa, Saccharomyces cerevisiae). The 3-pyridylalkyne derivatives viz., 3-(6-chloropyridin-3-yl)propynenitrile (6a), 3-(2-chloropyridin-3-yl)propynenitrile (6b), ethyl 3-(6-chloropyridin-3-yl)propiolate (6c), iso-propyl 3-(6-chloropyridin-3-yl)propiolate (6d) and 3-(2,6-dichloro-5-fluoropyridin-3-yl)propynenitrile (6e) were found to be highly potent towards all tested microorganisms except E. coli.