Design and environmentally benign synthesis of novel thiophene appended pyrazole analogues as anti-inflammatory and radical scavenging agents: Crystallographic , in silico modeling, docking and SAR characterization

An Update on the synthesis and pharmacological properties of pyrazoles obtained from Chalcone

Abstract:

A review concerning the synthesis and pharmacological properties of pyrazoles obtained from Chalcone described in the literature over the last 5 years (2016-2020) was presented and discussed. Among the synthetic approaches for pyrazoles described so far, the cyclization and acetylation method of α,β-unsaturated chalcones and substituted hydrazine was selected and analyzed. 105 pyrazole derivatives (3-107) were evaluated as well as their pharmacological activities, namely, antineoplastic, anti-inflammatory, antioxidant, antibacterial, antifungal, antimycobacterial, antiplasmodial, Alzheimer's disease, enzymes inhibition (like acetylcholinesterase, carbonic anhydrase, and malonyl CoA decarboxylase), anticonvulsant, among others. Pyrazolic compounds are widely used in the new drugs design with a wide spectrum of pharmacological approaches, therefore, it is relevant to research the synthetic methods and therapeutic properties of different pyrazole derivatives.

Development of pyrazole derivatives in the management of inflammation

The therapeutic limitations and poor management of inflammatory conditions are anticipated to impact patients negatively over the coming decades. Following the synthesis of the first pyrazole-antipyrine in 1887, several other derivatives have been screened for anti-inflammatory, analgesic, and antipyretic activities. Arguably, the pyrazole ring, as a major pharmacophore and central scaffold partly, defines the pharmacological profile of several derivatives. In this review, we explore the structural-activity relationship that accounts for the pharmacological profile of pyrazole derivatives and highlights future research perspectives capable of optimizing current advancement in the search for safe and efficacy anti-inflammatory drugs. The flourishing research into the pyrazole derivatives as drug candidates has advanced our understanding of inflammation-related diseases and treatment.

Design, synthesis and in silico study of pyridine based 1,3,4-oxadiazole embedded hydrazinecarbothioamide derivatives as potent anti-tubercular agent

Development of novel, safe and effective drug candidates combating the emerging drug resistance has remained a major focus in the mainstream of anti-tuberculosis research. Here, we inspired to design and synthesize series of new pyridin-4-yl-1,3,4-oxadiazol-2-yl-thio-ethylidene-hydrazinecarbothioamide derivatives as potential anti-tubercular agents. The anti-tubercular bioactive assay demonstrated that the synthesized compounds exhibit potent anti-tubercular activity (MIC = 3.9-7.81 μg/mL) in comparison with reference drugs Rifampicin and Isoniazid.We employed pharmacophore probing approach for the identification of CYP51 as a possible drug target for the synthesized compounds. To understand the preferable binding mode, the synthesized molecules were docked onto the active site of Sterol 14 α-demethylases (CYP51) target. From the binding free energy of the docking results it was revealed that the compounds were effective CYP51 inhibitors and acts as antitubercular agent.

Excellent antitumor and antimetastatic activities based on novel coumarin/pyrazole oxime hybrids

A series of hybrids 10a-v based on coumarin/pyrazole oxime have been synthesized, and exhibit good to excellent antitumor activities. Compound 10n has shown remarkable anticancer effect on SMMC-7721 cells (IC₅₀ = 2.08 μM), which is considerably lower than 5-FU (IC₅₀ = 37.8 μM) and similar to ADM (IC₅₀ = 2.67 μM), with little effect on normal hepatic cells LO2. Notably, the suppression experiments of metastatic activities reveal that 10n also displays significant anti-metastasis effects through inhibiting cell migration and invasion in highly metastatic SMMC-7721 cell line, and dose-dependently reverses TGF-β1-induced epithelial-mesenchymal transition (EMT) procedure better than ADM. Finally, 10n also possesses low acute toxicity and potent tumor growth inhibitory property against SMMC-7721 cell lines in vivo. Our findings suggest that novel coumarin/pyrazole oxime hybrids are promising therapeutic agent candidates for further research.

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.

Current progress on antioxidants incorporating the pyrazole core

The search of new antioxidants, as drugs candidates, is an active field of medicinal chemistry. The synthesis of compounds with antioxidant potential has increased in recent years and a high number of structurally diverse compounds have been published. This review aims to show the current state-of-the-art on the development of antioxidant compounds incorporating the pyrazole pharmacophore. It is a well-timed review driven by the increasing number of papers, on this issue, that have been published since the beginning of the 21st century (from 2000 to 2017). The aim is to look deeper into the structures already published in the literature containing the pyrazole core as the unique pharmacophore or combined with other pharmacophores and see the relationship between the presence of this five-membered nitrogen heterocycle and the behaviour of the compounds as potential antioxidant agents. An attempt was made to whenever possible establish structure-activity relationships that could help the design of new and more potent antioxidant agents containing this important pharmacophore.