Multiple biological active 4-aminopyrazoles containing trifluoromethyl and their 4-nitroso-precursors: Synthesis and evaluation

Structure-Activity Relationship Studies on Highly Functionalized Pyrazole Hydrazones and Amides as Antiproliferative and Antioxidant Agents

Aminopyrazoles represent interesting structures in medicinal chemistry, and several derivatives showed biological activity in different therapeutic areas. Previously reported 5-aminopyrazolyl acylhydrazones and amides showed relevant antioxidant and anti-inflammatory activities. To further extend the structure-activity relationships in this class of derivatives, a novel series of pyrazolyl acylhydrazones and amides was designed and prepared through a divergent approach. The novel compounds shared the phenylamino pyrazole nucleus that was differently decorated at positions 1, 3, and 4. The antiproliferative, antiaggregating, and antioxidant properties of the obtained derivatives 10-22 were evaluated in in vitro assays. Derivative 11a showed relevant antitumor properties against selected tumor cell lines (namely, HeLa, MCF7, SKOV3, and SKMEL28) with micromolar IC50 values. In the platelet assay, selected pyrazoles showed higher antioxidant and ROS formation inhibition activity than the reference drugs acetylsalicylic acid and N-acetylcysteine. Furthermore, in vitro radical scavenging screening confirmed the good antioxidant properties of acylhydrazone molecules. Overall, the collected data allowed us to extend the structure-activity relationships of the previously reported compounds and confirmed the pharmaceutical attractiveness of this class of aminopyrazole derivatives.

Trifluoromethyl-β-dicarbonyls as Versatile Synthons in Synthesis of Heterocycles

Trifluoromethyl group relishes a privileged position in the realm of medicinal chemistry because its incorporation into organic molecules often enhances the bioactivity by altering pharmacological profile of molecule. Trifluoromethyl-β-dicarbonyls have emerged as pivotal building blocks in synthetic organic chemistry due to their facile accessibility, stability and remarkable versatility. Owing to presence of nucleophilic and electrophilic sites, they offer multifunctional sites for the reaction. This review covers a meticulous exploration of their multifaceted role, encompassing an in-depth analysis of mechanism, extensive scope, limitations and wide-ranging applications in diverse organic synthesis, covering the literature from the 21st century. This comprehensive review encapsulates the applications of trifluoromethyl-β-dicarbonyls and their synthetic equivalents as precursors of complex and diverse heterocyclic scaffolds, fused heterocycles and spirocyclic compounds having medicinal and material importance. Their potent synthetic utility in cyclocondensation reactions with binucleophiles, cycloaddition reactions, C-C bond formations, asymmetric multicomponent reactions using classical/solvent-free/catalytic synthesis have been presented. Influence of unsymmetrical trifluoromethyl-β-diketones on regioselectivity of transformation is also reviewed. This review will benefit the synthetic and pharmaceutical communities to explore trifluoromethyl-β-dicarbonyls as trifluoromethyl building blocks for fabrication of heterocyclic scaffolds having implementation into drug discovery programs in the imminent future.

Deep Learning with Geometry-Enhanced Molecular Representation for Augmentation of Large-Scale Docking-Based Virtual Screening

Structure-based virtual screening has been a crucial tool in drug discovery for decades. However, as the chemical space expands, the existing structure-based virtual screening techniques based on molecular docking and scoring struggle to handle billion-entry ultralarge libraries due to the high computational cost. To address this challenge, people have resorted to machine learning techniques to enhance structure-based virtual screening for efficiently exploring the vast chemical space. In those cases, compounds are usually treated as sequential strings or two-dimensional topology graphs, limiting their ability to incorporate three-dimensional structural information for downstream tasks. We herein propose a novel deep learning protocol, GEM-Screen, which utilizes the geometry-enhanced molecular representation of the compounds docking to a specific target and is trained on docking scores of a small fraction of a library through an active learning strategy to approximate the docking outcome for yet nontraining entries. This protocol is applied to virtual screening campaigns against the AmpC and D4 targets, demonstrating that GEM-Screen enriches more than 90% of the hit scaffolds for AmpC in the top 4% of model predictions and more than 80% of the hit scaffolds for D4 in the same top-ranking size of library. GEM-Screen can be used in conjunction with traditional docking programs for docking of only the top-ranked compounds to avoid the exhaustive docking of the whole library, thus allowing for discovering top-scoring compounds from billion-entry libraries in a rapid yet accurate fashion.

5-Alkoxy-1-aryl-3-polyfluoroalkylpyrazoles with Antinociceptive Activity: Partial Agonists of TRPV1 Ion Channels

Chemoselective O-alkylation of 1-aryl-3-polyfluoroalkylpyrazol-5-oles under basic conditions resulted in a series of 5-alkoxypyrazoles (26 derivatives). They showed an acceptable ADME profile (in silico) and can be considered as drug-like. In experiments in vivo (CD-1 mice), it was found that the obtained compounds do not have toxic properties at a dose of more than 150 mg/kg (for most compounds at a dose of >300 mg/kg, and for lead compounds - >600 mg/kg). 22 Compounds from this series demonstrated from moderate to high analgesic effects (28-104 % at 1 h and 37-109 % at 2 h after administration) in vivo in the hot plate test (SD rats, 15 mg/kg, intraperitoneal (ip)). The lead compound was 4-([1-phenyl-3-(trifluoromethyl)pyrazol-5-yl]oxy)butan-1-ol, which not only increased the latent period in the hot plate test by 103 % at both measurement points but also showed a pronounced analgesic effect under conditions of capsaicin-induced nociception (CD-1 mice, 15 mg/kg, ip). According to molecular modeling, all synthesized compounds can interact with the TRPV1 ion channel. This biological target was confirmed in in vitro experiments on Chinese hamster ovary cells expressing rTRPV1. 5-Alkoxypyrazoles were partial agonists of the TRPV1 ion channel in various degree, and the most active was the same pyrazole as in in vivo tests.

Amino-Pyrazoles in Medicinal Chemistry: A Review

A pyrazole nucleus is an easy-to-prepare scaffold with large therapeutic potential. Consequently, the search for new pyrazole-based compounds is of great interest to the academic community as well as industry. In the last ten years, a large number of papers and reviews on the design, synthesis, and biological evaluation of different classes of pyrazoles and many pyrazole-containing compounds have been published. However, an overview of pyrazole derivatives bearing a free amino group at the 3, 4, or 5 position (namely, 3-aminopyrazoles, 4-aminopyrazoles, and 5-aminopyrazoles, respectively) and their biological properties is still missing, despite the fact that aminopyrazoles are advantageous frameworks able to provide useful ligands for receptors or enzymes, such as p38MAPK, and different kinases, COX and others, as well as targets important for bacterial and virus infections. With the aim to fill this gap, the present review focuses on aminopyrazole-based compounds studied as active agents in different therapeutic areas, with particular attention on the design and structure-activity relationships defined by each class of compounds. In particular, the most relevant results have been obtained for anticancer/anti-inflammatory compounds, as the recent approval of Pirtobrutinib demonstrates. The data reported here are collected from different databases (Scifinder, Web of Science, Scopus, Google Scholar, and Pubmed) using "aminopyrazole" as the keyword.

Regioselective synthesis of novel nitroso-pyrazolylquinoxalines via HOAc-mediated cyclocondensation of 2-hydroxyimino-1,3-diketones with hydrazinylquinoxalines

This article describes the regioselective synthesis of novel nitroso-pyrazolylquinoxalines via cyclocondensation of 2-hydroxyimino-1,3-diketones with hydrazinylquinoxalines. Of note, this is the first time that 2-hydroxyimino-1,3-diketones are used as electrophilic reagents to cyclocondensation with hetarylhydrazines. The cyclocondensation proceeded through a hydrazone intermediates formation. A series of novel nitroso-substituted pyrazolylquinoxalines were synthesized by both "one-pot" and "two-step" procedures in up to 86% yields. Importantly, a gram-scale synthesis of nitroso-pyrazolylquinoxalines, their oxidation and reduction were successfully accomplished.

Synthesis, spectral characterization of pyrazole derived Schiff base analogs: molecular dynamic simulation, antibacterial and DNA binding studies

We have synthesized the pyrazole-bearing Schiff base derivatives (5a-5e) and (6a-6h) then the structural confirmation was supported by various spectral analyses. The antibacterial activity of all analogs was screened against bacterial strains Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Klebsiella pneumonieae and Pseudomonas aeruginosa. In comparison to the reference drug ciprofloxacin, the lead analogs 5c and 6c showed potent activity, with MIC values of 64 µg/mL against E. coli and B. subtilis. Compound 5c showed a moderate effect with a MIC value of 128 µg/mL against B. subtilis, P. aeruginosa and K. pneumonieae, while compound 6c was against E. coli and P. aeruginosa. Furthermore, the compounds 5c and 6c displayed groove binding mode towards CT-DNA by absorption, emission, competitive fluorescence studies using EtBr, CD and time-resolved fluorescence studies. Thermodynamic parameters of analogs 5c and 6c with CT-DNA were also calculated at 298, 303 and 308K temperatures by UV-visible spectroscopy. The molecular docking studies give the docking score for all compounds with PDB codes: 1BNA and 2XCT. The MD simulation study of analogs 5c and 6c was also carried out. The pharmacokinetic and ADME properties were calculated for all of the synthesized analogs (5a-5e) and (6a-6h).Communicated by Ramaswamy H. Sarma.

Synthesis of 4-Aminopyrazol-5-ols as Edaravone Analogs and Their Antioxidant Activity

One of the powerful antioxidants used clinically is Edaravone (EDA). We synthesized a series of new EDA analogs, 4-aminopyrazol-5-ol hydrochlorides, including polyfluoroalkyl derivatives, via the reduction of 4-hydroxyiminopyrazol-5-ones. The primary antioxidant activity of the compounds in comparison with EDA was investigated in vitro using ABTS, FRAP, and ORAC tests. In all tests, 4-Amino-3-pyrazol-5-ols were effective. The lead compound, 4-amino-3-methyl-1-phenylpyrazol-5-ol hydrochloride (APH), showed the following activities: ABTS, 0.93 TEAC; FRAP, 0.98 TE; and ORAC, 4.39 TE. APH and its NH-analog were not cytotoxic against cultured normal human fibroblasts even at 100 μM, in contrast to EDA. According to QM calculations, 4-aminopyrazolols were characterized by lower gaps, IP, and η compared to 4-hydroxyiminopyrazol-5-ones, consistent with their higher antioxidant activities in ABTS and FRAP tests, realized by the SET mechanism. The radical-scavenging action evaluated in the ORAC test occurred by the HAT mechanism through OH bond breaking in all compounds, directly dependent on the dissociation energy of the OH bond. All the studied compounds demonstrated the absence of anticholinesterase activity and moderate inhibition of CES by some 4-aminopyrazolols. Thus, the lead compound APH was found to be a good antioxidant with the potential to be developed as a novel therapeutic drug candidate in the treatment of diseases associated with oxidative stress.

A Review of the Recent Development in the Synthesis and Biological Evaluations of Pyrazole Derivatives

Pyrazoles are five-membered heterocyclic compounds that contain nitrogen. They are an important class of compounds for drug development; thus, they have attracted much attention. In the meantime, pyrazole derivatives have been synthesized as target structures and have demonstrated numerous biological activities such as antituberculosis, antimicrobial, antifungal, and anti-inflammatory. This review summarizes the results of published research on pyrazole derivatives synthesis and biological activities. The published research works on pyrazole derivatives synthesis and biological activities between January 2018 and December 2021 were retrieved from the Scopus database and reviewed accordingly.