1,3-Diarylcycloalkanopyrazoles and diphenyl hydrazides as selective inhibitors of cyclooxygenase-2

A novel class of potent antiangiogenic and antioxidant pyrazoles: synthesis, bioactivity, docking and ADMET studies

Aim: Angiogenesis is the hallmark of cancer progression driven by VEGF/VEGFR-2 signalling pathway, inhibition of which could be a solution to tackle the progression of tumour cells and thus arresting their growth.Materials & methods: A novel class of pyrazoles was synthesized using arginine and dibromo ketones. Antiangiogenic activity was performed by in vivo yolk sac method. Antioxidant activity was evaluated by hydroxyl and superoxide radical scavenging assays. Docking studies were performed to determine the pyrazoles' binding potential with VEGFR-2 receptor and VEGF tyrosine kinase. ADMET properties were calculated using SwissADME and admetSAR for drug-likeness.Results: Compounds 5a-e showed significant antiangiogenic effects. Compound 5f exhibited effective hydroxyl and superoxide radical scavenging activities. Docking results confirmed the potential binding efficiency with VEGFR-2 receptor over VEGF tyrosine kinase, thus, functioning as competitive-inhibitors. ADMET studies revealed that the compounds possess favourable drug-like qualities.Conclusion: This study presents a novel class of pyrazoles as promising antioxidant and antiangiogenic agents with favourable drug-likeness properties.

Regioselective Synthesis, Structural Characterization, and Antiproliferative Activity of Novel Tetra-Substituted Phenylaminopyrazole Derivatives

A small library of highly functionalized phenylaminopyrazoles, bearing different substituents at position 1, 3, and 4 of the pyrazole ring, was prepared by the one-pot condensation of active methylene reagents, phenylisothiocyanate, and substituted hydrazine (namely, methyl- and benzyl-hydrazine). The identified reaction conditions proved to be versatile and efficient. Furthermore, the evaluation of alternative stepwise protocols affected the chemo- and regio-selectivity outcome of the one-pot procedure. The chemical identities of two N-methyl pyrazole isomers, selected as prototypes of the whole series, were unambiguously identified by means of NMR and mass spectrometry studies. Additionally, semiempirical calculations provided a structural rationale for the different chromatographic behavior of the two isomers. The prepared tetra-substituted phenylaminopyrazoles were tested in cell-based assays on a panel of cancer and normal cell lines. The tested compounds did not show any cytotoxic effect on the selected cell lines, thus supporting their pharmaceutical potentials.

Sustainable synthesis of pyrazoles using alcohols as the primary feedstock by an iron catalyzed tandem C–C and C–N coupling approach

We report two new efficient iron-catalyzed synthetic strategies for multicomponent synthesis of tri-substituted pyrazoles using biomass-derived alcohols as the primary feedstock.

Continuous flow synthesis of Celecoxib from 2-bromo-3,3,3-trifluoropropene

We describe the total flow synthesis of the widely prescribed anti-inflammatory COX-2 inhibitor Celecoxib from 2-bromo-3,3,3-trifluoropropene, as a convenient and available trifluoromethyl building block, to generate trifluoropropynyl lithium and to trap it immediately with an aldehyde. Oxidation of the obtained alcohol into ketone followed by condensation with 4-sulfamidophenylhydrazine afforded the targeted drug with full regioselectivity. It is noteworthy that the quality of these flow reactions (50% overall yield within 1 h cumulated residence time over 3 steps) directly furnished the target API and intermediates with excellent purity.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s41981-021-00205-x.

Utility of novel 2-furanones in synthesis of other heterocyclic compounds having anti-inflammatory activity with dual COX2/LOX inhibition

Inflammation is associated with the development of several diseases comprising cancer and cardiovascular disease. Agents that suppress cyclooxygenase (COX) and lipoxygenase (LOX) enzymes, besides chemokines have been suggested to minimise inflammation. Here, a variety of novel heterocyclic and non-heterocyclic compounds were prepared from novel three furanone derivatives. The structures of all synthesised compounds were confirmed by elemental and spectral analysis including mass, IR, and ¹H-NMR spectroscopy. Anti-inflammatory activities of these synthesised compounds were examined in vitro against COX enzymes, 15-LOX, and tumour necrosis factor-α (TNF-α), using inhibition screening assays. The majority of these derivatives showed significant to high activities, with three pyridazinone derivatives (5b, 8b, and 8c) being the most promising anti-inflammatory agents with dual COX-2/15-LOX inhibition activities along with high TNF-α inhibition activity.

Classification of Cyclooxygenase-2 Inhibitors Using Support Vector Machine and Random Forest Methods

This work reports the classification study conducted on the biggest COX-2 inhibitor data set so far. Using 2925 diverse COX-2 inhibitors collected from 168 pieces of literature, we applied machine learning methods, support vector machine (SVM) and random forest (RF), to develop 12 classification models. The best SVM and RF models resulted in MCC values of 0.73 and 0.72, respectively. The 2925 COX-2 inhibitors were reduced to a data set of 1630 molecules by removing intermediately active inhibitors, and 12 new classification models were constructed, yielding MCC values above 0.72. The best MCC value of the external test set was predicted to be 0.68 by the RF model using ECFP_4 fingerprints. Moreover, the 2925 COX-2 inhibitors were clustered into eight subsets, and the structural features of each subset were investigated. We identified substructures important for activity including halogen, carboxyl, sulfonamide, and methanesulfonyl groups, as well as the aromatic nitrogen atoms. The models developed in this study could serve as useful tools for compound screening prior to lab tests.

Rational Use of Heterogeneous Data in Quantitative Structure-Activity Relationship (QSAR) Modeling of Cyclooxygenase/Lipoxygenase Inhibitors

Numerous studies have been published in recent years with acceptable quantitative structure-activity relationship (QSAR) modeling based on heterogeneous data. In many cases, the training sets for QSAR modeling were constructed from compounds tested by different biological assays, contradicting the opinion that QSAR modeling should be based on the data measured by a single protocol. We attempted to develop approaches that help to determine how heterogeneous data should be used for the creation of QSAR models on the basis of different sets of compounds tested by different experimental methods for the same target and the same endpoint. To this end, more than 100 QSAR models for the IC50 values of ligands interacting with cyclooxygenase 1,2 (COX) and seed lipoxygenase (LOX), obtained from ChEMBL database were created using the GUSAR software. The QSAR models were tested on the external set, including 26 new thiazolidinone derivatives, which were experimentally tested for COX-1,2/LOX inhibition. The IC50 values of the derivatives varied from 89 μM to 26 μM for LOX, from 200 μM to 0.018 μM for COX-1, and from 210 μM to 1 μM for COX-2. This study showed that the accuracy of the models is dependent on the distribution of IC50 values of low activity compounds in the training sets. In the most cases, QSAR models created based on the combined training sets had advantages in comparison with QSAR models, based on a single publication. We introduced a new method of combination of quantitative data from different experimental studies based on the data of reference compounds, which was called "scaling".

The use of enaminones and enamines as effective synthons for MSA-catalyzed regioselective synthesis of 1,3,4-tri- and 1,3,4,5-tetrasubstituted pyrazoles

In the present work, an efficient regioselective synthesis of 1,3,4-tri- and 1,3,4,5-tetrasubstituted pyrazoles via a methanesulfonic acid (MSA)-catalyzed reaction of hydrazones with enaminones or enamines is reported.

SAR and QSAR models of cyclooxygenase-1 (COX-1) inhibitors

Cyclooxygenase-1 (COX-1) is one isoform of COX, and it is a main target of nonsteroidal anti-inflammatory drugs (NSAIDs). It is important to develop efficient and selective COX-1 inhibitors. In this work, 12 classification models for 1530 cyclooxygenase-1 (COX-1) inhibitors were built by support vector machine (SVM), decision tree (DT) and random forest (RF) methods. The best classification model (model 1A) was built by SVM with MACCS fingerprints. The classification accuracies for the training and test sets were 99.67% and 97.39%, respectively. The Matthews correlation coefficient (MCC) of the test set was 0.94. We also divided the 1530 COX-1 inhibitors into nine subsets according to their different scaffolds using Kohonen's self-organizing map (SOM). In addition, six quantitative structure-activity relationship (QSAR) models for 181 COX-1 inhibitors whose IC₅₀ were measured by enzyme immunoassay were built by multiple linear regression (MLR) and SVM. The best QSAR model (model 5A) was built by SVM with CORINA Symphony descriptors. The correlation coefficients of the training and test sets are 0.93 and 0.84, respectively. The models built in this study can be obtained from the authors.

Design and Amberlyst-15 mediated synthesis of novel thienyl-pyrazole carboxamides that potently inhibit Phospholipase A2 by binding to an allosteric site on the enzyme

Inflammation-mediated disorders are on the rise and hence, there is an urgent need for the design and synthesis of new anti-inflammatory drugs with higher affinity and specificity for their potential targets. The current study presents an effective and new protocol for the synthesis of thienyl-pyrazoles through 3 + 2 annulations using a recyclable heterogeneous catalyst Amberlyst-15. Chalcones 3(a-g) prepared from 3-methylthiophene-2-carbaldehyde and acetophenones by Claisen-Schmidt approach reacted with semicarbazide hydrochloride 4 in the presence of Amberlyst-15 in acetonitrile at room temperature producing thienyl-pyrazole carboxamides 5(a-h) in good yields. Alternatively, the compounds 5(a-h) were prepared by conventional method using acetic acid (30%) medium. Structures of synthesized new pyrazoles were confirmed by spectral and crystallographic studies. All the new compounds were evaluated for their in vitro inhibition of Phospholipase A2 from Vipera russelli and preliminary studies revealed that, amongst the designed series, compounds 5b, 5c and 5h showed promising inhibition. Further, the compounds exhibited linear mixed-type inhibition behavior for the sPLA2 enzyme indicating that they bind to an allosteric site distinct from either the calcium or substrate binding site on the enzyme. These kinetic conclusions were further validated by macromolecular rigid-body docking whereby compounds 5c and 5h showed binding to distinct pockets on the protein. These findings present a promising series of lead molecules that can serve as prototypes for the treatment of inflammatory related disorders.

Visible-Light Photocatalysis: Does It Make a Difference in Organic Synthesis?

Visible-light photocatalysis has evolved over the last decade into a widely used method in organic synthesis. Photocatalytic variants have been reported for many important transformations, such as cross-coupling reactions, α-amino functionalizations, cycloadditions, ATRA reactions, or fluorinations. To help chemists select photocatalytic methods for their synthesis, we compare in this Review classical and photocatalytic procedures for selected classes of reactions and highlight their advantages and limitations. In many cases, the photocatalytic reactions proceed under milder reaction conditions, typically at room temperature, and stoichiometric reagents are replaced by simple oxidants or reductants, such as air, oxygen, or amines. Does visible-light photocatalysis make a difference in organic synthesis? The prospect of shuttling electrons back and forth to substrates and intermediates or to selectively transfer energy through a visible-light-absorbing photocatalyst holds the promise to improve current procedures in radical chemistry and to open up new avenues by accessing reactive species hitherto unknown, especially by merging photocatalysis with organo- or metal catalysis.

Design, synthesis and biological evaluation of novel 1,3-diarylpyrazoles as cyclooxygenase inhibitors, antiplatelet and anticancer agents

With the aim of achieving new compounds possessing both anti-inflammatory and antiplatelet activities, we synthesized (E)-3-[3-(pyridin-3/4-yl)-1-(phenyl/sulfonylmethylphenyl)-1H-pyrazol-4-yl]acrylamides, and evaluated their COX-1 and COX-2 inhibitory and antiplatelet activities. Since COX-2 inhibitory and antiplatelet compounds have anticancer potential, we also screened their antiproliferative effects against three human cancer cell lines. Compounds 5n, 5p, 5s, 10d, 10g and 10i were determined as dual COX-2 inhibitor/antiplatelet compounds. Compound 10h appeared to be a compound that exhibited antiplatelet activity without inhibiting the COX enzyme. Compounds 5h, 10a and 10i were the most effective derivatives which displayed antiproliferative activity against Huh7, MCF7 and HCT116 cells. Particularly, compound 10i, as the compound exhibiting the highest cytotoxic, antiplatelet and COX-2 inhibitory activity, was remarkable.

Easy and rapid preparation of benzoylhydrazides and their diazene derivatives as inhibitors of 15-lipoxygenase

Two series of diaza derivatives were prepared by solvent-free condensation of benzoic acid and 4-substituted phenylhydrazines in order to obtain phenylhydrazides (HYD series) and, by oxidation of these compounds, the corresponding benzoyldiazenes (DIA series). Both sets were evaluated as inhibitors of soybean 15-lipoxygenase activity and antioxidant capability in the FRAP and CUPRAC assays. The most potent inhibitors of both series exhibited IC50 values in the low micromolar range. Kinetic studies showed that at least the more active compounds were competitive inhibitors. Docking results indicated that the most potent inhibitor interacts strongly with Ile-839 and iron in the active site.

Brönsted acid-mediated annulations of 1-cyanocyclopropane-1-carboxylates with arylhydrazines: efficient strategy for the synthesis of 1,3,5-trisubstituted pyrazoles

A diversity-oriented synthesis of 1H-pyrazole derivatives via Brönsted acid-promoted annulations of 1-cyanocyclopropane-1-carboxylates with arylhydrazines has been developed.

Theoretical and experimental investigation of the polyeletrophilic β-enamino diketone: straightforward and highly regioselective synthesis of 1,4,5-trisubstituted pyrazoles and pyrazolo[3,4-d]pyridazinones

A highly efficient regioselective synthesis of 1,4,5-trisubstituted pyrazoles and pyrazolo[3,4-d]pyridazinones from enamino diketone along with a theoretical and experimental study of the chemical reactivity enamino diketone.

I2-mediated oxidative C-N bond formation for metal-free one-pot synthesis of di-, tri-, and tetrasubstituted pyrazoles from α,β-unsaturated aldehydes/ketones and hydrazines

An I2-mediated metal-free oxidative C-N bond formation methodology has been established for the regioselective pyrazole synthesis. This practical and eco-friendly one-pot protocol requires no isolation of the less stable intermediates hydrazones and provides a facile access to a variety of di-, tri-, and tetrasubstituted (aryl, alkyl, and/or vinyl) pyrazoles from readily available α,β-unsaturated aldehydes/ketones and hydrazine salts.

Design and synthesis of novel 2-phenyl-5-(1,3-diphenyl-1H-pyrazol-4-yl)-1,3,4-oxadiazoles as selective COX-2 inhibitors with potent anti-inflammatory activity

A novel series of 2-phenyl-5-(1,3-diphenyl-1H-pyrazol-4-yl)-1,3,4-oxadiazoles were designed and synthesized for selective COX-2 inhibition with potent anti-inflammatory activity. Among the compounds tested, 9g (2-(3-(4-nitrophenyl)-1-phenyl-1H-pyrazol-4-yl)-5-phenyl-1,3,4-oxadiazole) was found to be the most potent inhibitor of COX-2 with IC50 of 0.31 μM showing promising degree of anti-inflammatory activity in the carrageenan-induced rat paw edema model with ED50 of 74.3 mg/kg. The lead compound 9g further showed suppression of acetic acid-induced writhes comparable to that of aspirin and gastro-sparing profile superior to the aspirin. Molecular docking analysis displayed higher binding affinity of ligands towards COX-2 than COX-1.

Synthesis and in-silico studies of some diaryltriazole derivatives as potential cyclooxygenase inhibitors

The synthesis of several 4-phenyl-5-pyridin-4-yl-2,3-dihydro-3H-1,2,4-triazole-3-thiones possessing N-2 Mannich bases or S-alkyl substituents, is reported. Several of them exhibited a low nanomolar COX enzyme inhibition activity. Most of the compounds showed inhibition of edema was similar to that evoked by celocoxib in animal model. Molecular docking studies of the compounds into the binding sites of COX-1 and COX-2 allowed us to shed light on the binding mode of these novel COX inhibitors.

Synthesis of tri- and tetrasubstituted pyrazoles via Ru(II) catalysis: intramolecular aerobic oxidative C-N coupling

An unprecedented ruthenium(II)-catalyzed intramolecular oxidative C-N coupling method has been developed for the facile synthesis of a variety of synthetically challenging tri- and tetrasubstituted pyrazoles. Dioxygen gas is employed as the oxidant in this transformation. The reaction demonstrates excellent reactivity, functional group tolerance, and high yields.