Synthesis and Anti-HIV-1 Activity Evaluation for Novel 3a,6a-Dihydro-1H-pyrrolo[3,4-c]pyrazole-4,6-dione Derivatives

Diastereomeric pure pyrazolyl-indolyl dihydrofurans: Unveiling isomeric selectivity in antibacterial action via in vitro and in silico insights

Developing pure diastereoisomeric molecular hybrids for the selective inhibition of bacterial growth opened new avenues for combating the ever-increasing microbial resistance. Considering this, a series of diastereoisomeric pure pyrazolyl-dihydrofurans (7a-7y) were synthesized and characterized using NMR, LCMS, and X-ray crystallography. DFT based method was used to explore the configurational stability of cis over trans isomeric form. Considering 7a and 8a as representative isomeric forms with same structural framework, the difference in their bio-efficacy against bacterial and fungal strains was assessed using serial dilution method. The relatively high inhibition of bacterial growth by the cis isomeric form (7a) (MIC = 1.562 µg/mL), amoxicillin (MIC = 3.125 µg/mL) inspired us to broaden the substrate scope for synthesizing a series of pure diastereoisomeric cis forms as selective anti-bacterial agents. However, both the isomers displayed antifungal activity less than the standard drug (Fluconazole) employed in the study. All the reactions proceeded smoothly and yielded a diverse array of dihydrofuran derivatives. The developed synthetics were found to be non-cytotoxic against mouse fibroblast cells and didn't affect the seed germination of Brassica nigra seeds when treated at 1 mg/mL concentration. The experimentally determined in vitro results were further validated using in silico molecular docking and dynamics studies.

N-Heterocycles as Promising Antiviral Agents: A Comprehensive Overview

Viruses are a real threat to every organism at any stage of life leading to extensive infections and casualties. N-heterocycles can affect the viral life cycle at many points, including viral entrance into host cells, viral genome replication, and the production of novel viral species. Certain N-heterocycles can also stimulate the host's immune system, producing antiviral cytokines and chemokines that can stop the reproduction of viruses. This review focused on recent five- or six-membered synthetic N-heterocyclic molecules showing antiviral activity through SAR analyses. The review will assist in identifying robust scaffolds that might be utilized to create effective antiviral drugs with either no or few side effects.

Access and Modulation of Substituted Pyrrolo[3,4-c]pyrazole-4,6-(2H,5H)-diones

The first access to polyfunctionnalized pyrrolo[3,4-c]pyrazole-4,6-(2H,5H)-dione derivatives is reported. The series were generated from diethyl acetylenedicarboxylate and arylhydrazines, which afforded the key intermediates bearing two functional positions. The annellation to generate the maleimide moiety of the bicycle was studied. Moreover, an efficient palladium-catalyzed C-C and C-N bond formation via Suzuki-Miyaura or Buchwald-Hartwig coupling reactions in C-6 position was investigated from 6-chloropyrrolo[3,4-c]pyrazole-4,6-(2H,5H)-diones. This method provides novel access to various 1,6 di-substituted pyrrolo[3,4-c] pyrazole-4,6-(2H,5H)-diones.

Discovery of novel pyrazole and pyrazolo[1,5-a]pyrimidine derivatives as cyclooxygenase inhibitors (COX-1 and COX-2) using molecular modeling simulation

Searching for effective and selective anti-inflammatory agents, our study involved designing and synthesizing new pyrazole and pyrazolo[1,5-a]pyrimidine derivatives 4-11. The structures of the synthesized derivatives were confirmed using different spectroscopic techniques. Virtual screening was achieved for the newly designed derivatives using in silico docking simulation inside the active sites of four proteins classified as two cyclooxygenases (COX)-1 (PDB: 3KK6 and 4OIZ) and two COX-2 (PBD: 1CX2 and 3LN1). Among them, six derivatives 4c, 5b, 6a, 7a, 7b, and 10b displayed the highest binding energy. These derivatives were evaluated for their in vitro COX-1 and COX-2 inhibitory activities and their selectivity indexes were calculated. Additionally, these derivatives displayed IC₅₀ values ranging between 4.909 ± 0.25 and 57.53 ± 2.91 µM, and 3.289 ± 0.14 and 124 ± 5.32 µM, against COX-1 and COX-2, respectively. Furthermore, the tested derivatives were found to have selective inhibitory activity on the COX-2 enzyme. Surprisingly, the two pyrazole derivatives 4c and 5b were found to be the most active, with IC₅₀ values of 9.835 ± 0.50 and 4.909 ± 0.25 µM and 4.597 ± 0.20 and 3.289 ±  0.14 µM compared with meloxicam (1.879 ± 0.1 and 5.409 ±  0.23 µM) and celecoxib (5.439 ± 0.28 and 2.164 ± 0.09 µM) against COX-1/-2, respectively. Besides, two pyrazole derivatives, 4c and 5b, displayed a COX-1/COX-2 SI of 2.14 and 1.49. Computational techniques such as molecular docking, density function theory (DFT) calculation, and chemical absorption, distribution, metabolism, excretion, and toxicity evaluation were applied to explain the molecules' binding mode, chemical nature, drug likeness, and toxicity prediction.

Pyrazole Containing Anti-HIV Agents: An Update

BACKGROUND

Pyrazole scaffolds have gained importance in drug discovery and development for various pharmacological activities like antiviral, antifungal, anticancer, antidepressant, anti-inflammatory, antibacterial, etc. Additionally, the pyrazole moiety has shown potent anti-HIV activity as a core heterocycle or substituted heterocycles derivatives (mono, di, tri, tetra, and fused pyrazole derivatives). To assist the development of further potential anti-HIV agents containing pyrazole nucleus, here we have summarized pyrazole containing anti-HIV compounds that have been reported by researchers all over the world for the last two decades.

OBJECTIVE

The present review concentrates on an assortment of pyrazole containing compounds, particularly for potential therapeutic activity against HIV.

METHODS

Google Scholar, Pubmed, and SciFinder were searched databases with ''pyrazol'' keywords. Further, the year of publication and keywords ''Anti-HIV'' filter was applied to obtain relevant reported literature for anti-HIV agents containing pyrazole as a core or substituted derivatives.

RESULTS

This review article has shown the comprehensive compilation of 220 compounds containing pyrazole nucleus and possessing anti-HIV activity by sorting approximately 40 research articles from 2001 to date. 1-(4-Benzoylpiperazin-1-yl)-2-(4-fluoro-7-(1H-pyrazol-3-yl)-1H-pyrrolo[2,3-c]pyridin-3-yl)ethane-1,2-dione (13), 3-(3-(2-(4-benzoylpiperazin-1-yl)-2-oxoacetyl)-4-fluoro-1H-pyrrolo[2,3-c]pyridin-7-yl)-1H-pyrazole-5-carboxamide (31), 3-(3-(2-(4-benzoylpiperazin-1-yl)-2-oxoacetyl)-4-fluoro-1H-pyrrolo[2,3-c]pyridin-7-yl)-1H-pyrazole-5-carboxamide (88), 3-cyanophenoxypyrazole derivative (130), and 4-(4-chlorophenyl)-5-(4-methyl-5-((4-nitrophenyl)diazenyl)thiazol-2-yl)-3-phenyl-5,6-dihydro-4H-pyrazolo[4,3-d]isoxazole (178) were the most potent mono-, di-, tri-, tetra-substituted, and fused pyrazole derivatives, respectively, which have shown potent anti-HIV activity among all the described derivatives as compared with standard anti-HIV drugs.

CONCLUSION

This review article provides an overview of the potential therapeutic activity of pyrazole derivatives against HIV that will be helpful for designing pyrazole containing compounds for anti-HIV activity.

Design, synthesis, and cytotoxic activity of novel 2H-imidazo[1,2-c]pyrazolo[3,4-e]pyrimidine derivatives

In this study, a series of novel 2H-imidazo [1, 2-c] pyrazolo [3, 4-e] pyrimidine derivatives were designed, synthesized, and evaluated for their cytotoxic activities. The in vitro cell growth inhibition assay of the target compounds indicated their selectivity in inhibiting the proliferation of blood tumor cells (K562, U937) and solid tumor cells (HCT116, HT-29). Compound 9b exhibited the highest antiproliferative activities against K562 (IC₅₀ = 5.597 µM) and U937 (IC₅₀ = 3.512 µM). Based on the flow cytometry assays, compound 9b caused obvious induction of cell apoptosis and cell arrest at the S phase. Furthermore, western blot analysis revealed that compound 9b upregulated the expression of Bax, downregulated the levels of Bcl-2, and further activated caspase-3 in K562 cells. Therefore, compound 9b may be a potential anticancer agent that deserves further investigation.

A Cascade Reaction of Cinnamyl Azides with Acrylates Directly Generates Tetrahydro-Pyrrolo-Pyrazole Heterocycles

Developing reactions to generate complex and modular building blocks in a concise and direct fashion remains a contemporary synthetic challenge. This work describes a stereoselective cascade reaction between allylic azides and acrylates that directly generates tetrahydro-pyrrolo-pyrazole ring systems. These products contain up to four contiguous stereocenters, two of which may be tetrasubstituted carbon atoms attached to a nitrogen atom. Over 30 examples are provided with an average isolated yield of 71% (ranging from 40% to 94%). The reaction was easily scaled to use more than one gram of starting material, and the products can be readily diversified.

Pyrrolo[3,4- c]pyrazole Synthesis via Copper(Ι) Chloride-Catalyzed Oxidative Coupling of Hydrazones to Maleimides

A variety of pyrrolo[3,4- c]pyrazole derivatives from readily available aldehyde hydrazones and maleimides via direct oxidative coupling under radical cascade reaction have been reported. This method offers satisfactory chemical yields and good functional group compatibility. Moreover, this practical approach is catalyzed by CuCl utilizing air as the oxidant and some control experiments were performed to elaborate the mechanism.

Synthesis of Novel Pyrazole Derivatives and Their Tumor Cell Growth Inhibitory Activity

To find novel antitumor agents, a series of 1H-benzofuro[3,2-c]pyrazole derivatives 4a-e were designed and synthesized. The treatment of 6-methoxybenzofuran-3(2H)-one 3 with LiHMDS in anhydrous tetrahydrofuran (THF) followed by reaction with 3-substitued phenyl isothiocyanate gave the thioamide intermediates, which underwent condensation with hydrazine monohydrate in dioxane/EtOH (1:1) to provide the benzofuropyrazole derivatives 4a–e as well as the unexpected pyrazole derivatives 5a–e. In tumor cell growth inhibitory assay, all the benzofuropyrazole derivatives were not active against the breast tumor MCF-7 cell, only 4a was highly active and more potent than ABT-751 against the leukemia K562 (GI₅₀ = 0.26 μM) and lung tumor A549 cells (GI₅₀ = 0.19 μM), while other benzofuropyrazoles showed very weak inhibitory activity. In contrast, the pyrazoles 5a-e were in general more potent than the benzofuropyrazoles 4a–e. Compound 5a exhibited a similar tendency to that of 4a with high potency against K562 and A549 cells but weak effects on MCF-7 cell. Both pyrazoles 5b and 5e exhibited high inhibitory activities against K562, MCF-7 and A549 cells. The most active compound 5b was much more potent than ABT-751 against K562 and A549 cells with GI₅₀ values of 0.021 and 0.69 μM, respectively. Moreover, 5b was identified as a novel tubulin polymerization inhibitor with an IC₅₀ of 7.30 μM.

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.

Design, synthesis and antiviral evaluation of novel heteroarylcarbothioamide derivatives as dual inhibitors of HIV-1 reverse transcriptase-associated RNase H and RDDP functions

In the continuous effort to identify new HIV-1 inhibitors endowed with innovative mechanisms, the dual inhibition of different viral functions would provide a significant advantage against drug-resistant variants. The HIV-1 reverse transcriptase (RT)-associated ribonuclease H (RNase H) is the only viral-encoded enzymatic activity that still lacks an efficient inhibitor. We synthesized a library of 3,5-diamino-N-aryl-1H-pyrazole-4-carbothioamide and 4-amino-5-benzoyl-N-phenyl-2-(substituted-amino)-1H-pyrrole-3-carbothioamide derivatives and tested them against RNase H activity. We identified the pyrazolecarbothioamide derivative A15, able to inhibit viral replication and both RNase H and RNA-dependent DNA polymerase (RDDP) RT-associated activities in the low micromolar range. Docking simulations hypothesized its binding to two RT pockets. Site-directed mutagenesis experiments showed that, with respect to wt RT, V108A substitution strongly reduced A15 IC50 values (12.6-fold for RNase H inhibition and 4.7-fold for RDDP), while substitution A502F caused a 9.0-fold increase in its IC50 value for RNase H, not affecting the RDDP inhibition, reinforcing the hypothesis of a dual-site inhibition. Moreover, A15 retained good inhibition potency against three non-nucleoside RT inhibitor (NNRTI)-resistant enzymes, confirming a mode of action unrelated to NNRTIs and suggesting its potential as a lead compound for development of new HIV-1 RT dual inhibitors active against drug-resistant viruses.