Synthesis, crystal structures, fluorescence and xanthine oxidase inhibitory activity of pyrazole-based 1,3,4-oxadiazole derivatives

Triazole derivatives as potential xanthine oxidase inhibitors: Design, enzyme inhibition potential, and docking studies

Considerable ingenuity has been shown in the recent years in the discovery of novel xanthine oxidase (XO) inhibitors that fall outside the purine scaffold. The triazole nucleus has been the cornerstone for the development of many enzyme inhibitors for the clinical management of several diseases, where hyperuricemia is one of them. Here, we give a critical overview of significant research on triazole-based XO inhibitors, with respect to their design, synthesis, inhibition potential, toxicity, and docking studies, done till now. Based on these literature findings, we can expect a burst of modifications on triazole-based scaffolds in the near future by targeting XO, which will treat hyperuricemics, that is, painful conditions like gout that at present are hard to deal with.

Past, present and future of xanthine oxidase inhibitors: design strategies, structural and pharmacological insights, patents and clinical trials

Xanthine oxidase, a molybdo-flavoenzyme, and an isoform of xanthine dehydrogenase both exist as xanthine oxidoreductase and are responsible for purine catabolism. Xanthine oxidase is more involved in pathological conditions when extensively modulated. Elevation of xanthine oxidase is not only the prime cause of gout but is also responsible for various hyperuricemia associated pathological conditions like diabetes, chronic wounds, cardiovascular disorders, Alzheimer's disease, etc. Currently available xanthine oxidase inhibitors in clinical practice (allopurinol, febuxostat and topiroxostat) suffer from fatal side effects that pose a serious problem to the healthcare system, raising global emergency to develop novel, potent and safer xanthine oxidase inhibitors. This review will provide key and systematic information about: a. design strategies (inspired from both marketed drugs in clinical practice and natural products), structural insights and pharmacological output (xanthine oxidase inhibition and associated activities) of various pre-clinical candidates reported by various research groups across the globe in the past two decades; b. patented xanthine oxidase inhibitors published in the last three decades and c. clinical trials and their outcomes on approved drug candidates. Information generated in this review has suggested fragment-based drug design (FBDD) and molecular hybridization techniques to be most suitable for development of desired xanthine oxidase inhibitors as one provides high selectivity toward the enzyme and the other imparts multifunctional properties to the structure and both may possess capabilities to surpass the limitations of currently available clinical drugs. All in combination will exclusively update researchers working on xanthine oxidase inhibitors and allied areas and potentially help in designing rational, novel, potent and safer xanthine oxidase inhibitors that can effectively tackle xanthine oxidase related disease conditions and disorders.

Design, synthesis, and evaluation of tricyclic compounds containing phenyl-tetrazole as XOR inhibitors

Based on analyses of the interaction between febuxostat and xanthine oxidoreductase (XOR), tetrazole was used to replace the carboxyl-thiazole fragment of febuxostat using a bioelectronic isosteric strategy. Three series of compounds were designed. The inhibitory activity against XOR of all compounds was evaluated and their structure-activity relationships determined. The inhibitory activity against XOR of compounds I was weak, with a half-maximal inhibitory concentration (IC₅₀) value > 10 μmol, whereas the inhibitory activity of compounds II and III was increased significantly, among which compounds IIIa (IC₅₀ = 26.3 ± 1.21 nM) and IIIc (IC₅₀ = 29.3 ± 0.88 nM) were the best. Molecular docking showed that tetrazole could enter the active cavity instead of a carboxyl group and retain most of the interaction between febuxostat and XOR. For compounds III, the hydrogen bonds with Asn768 and Thr1010 of XOR were absent, but some new interactions were introduced to improve potency. A potassium oxazinate/hypoxanthine-induced model of acute hyperuricemia in mice also showed a significant hypouricemia effect of compounds IIIa, IIIc, and IIIe (P < 0.01), which was consistent with the results of inhibition in vitro. In conclusion, we identified a promising XOR inhibitor and provided new ideas for the design of XOR inhibitors.

Synthetic heterocyclic derivatives as promising xanthine oxidase inhibitors: An overview

Inhibition of xanthine oxidase is an effective and most prominent therapeutic approach for the management of gout. Discovery of its association in the pathophysiology of diabetes, cardiovascular disorders, etc., widened its therapeutic horizons. Limited drug candidates in clinical practice along with side effects forced researchers to develop more efficacious and safer xanthine oxidase inhibitors for the management of gout and other disorders associated with xanthine oxidase hyperactivity. In this regard, this review focus on: (a) Various drug candidates in clinical practice and under clinical trials, (b) Development of various heterocyclic motifs as xanthine oxidase inhibitors in last two decades and (c) Various patented synthetic xanthine oxidase inhibitors.

Recent updates on Synthetic Strategies and Biological Potential of 1,3,4-oxadiazole: Review

Abstract:

Among the large variety of nitrogen and oxygen-containing heterocycles, 1,3,4-oxadiazole, the scaffold, has attracted considerable attention owing to its ability to show an extensive range of pharmacological actions. According to literature investigations, prepared 1,3,4-oxadiazole and its derivative are pharmacologically significant and consist of a variety of activities, such as anticonvulsant, anticancer, antioxidant, anti-inflammatory, antibacterial, antidiabetic, etc. These heterocyclics are formed mainly by the cyclization reactions of various reactants under diverse reaction circumstances. Therefore, significant efforts of organic chemists have been directed towards the synthesis of new drug candidates containing 1,3,4-oxadiazole subunits connected to an established potential pharmacophore to improve the efficacy and potency. This article aims to highlight recent publications on the various synthesis techniques of 1,3,4-oxadiazole and related compounds over the previous ten years (2011–2021). The purpose of this review is to help researchers by summarizing several synthetic strategies for synthesizing oxadiazole.

Recent Progress on Anticancer Agents Incorporating Pyrazole Scaffold

The search of new anticancer agents is considered as a dynamic field of medicinal chemistry. In recent years, the synthesis of compounds with anticancer potential has increased and a large number of structurally varied compounds displaying potent anticancer activities have been published. Pyrazole is an important biologically active scaffold that possessed nearly all types of biological activities. The aim of this review is to collate literature work reported by researchers to provide an overview on in vivo and in vitro anticancer activities of pyrazole based derivatives among the diverse biological activities displayed by them and also presents recent efforts made on this heterocyclic moiety regarding anticancer activities. This review has been driven from the increasing number of publications, on this issue, which have been reported in the literature since the ending of the 20th century (from 1995-to date).

Inhibitors of Xanthine Oxidase: Scaffold Diversity and Structure-Based Drug Design

Xanthine oxidase (XO) is the enzyme responsible for the catabolism of purines and their conversion into uric acid. XO is thus the target for the treatment of hyperuricemia and gout. For more than 50 years the only XO inhibitor drug available on the market was the purine analogue allopurinol. In the last decade there has been a resurgence in the search for new inhibitors of XO, as the activity of XO and hyperuricemia have also been associated with a variety of conditions such as diabetes, hypertension, and other cardiovascular diseases. In recent years the non-purine inhibitor febuxostat was approved in Europe and the USA for the treatment of hyperuricemia. This drug was followed by another XO inhibitor called topiroxostat. This review discusses the molecular structures and activities of the multiple classes of inhibitors that have been developed since the discovery of allopurinol, with a brief review of the molecular interactions between inhibitors and XO active site residues for the most important molecules. The challenges ahead for the discovery of new inhibitors of XO with novel chemical structures are discussed.

Crystal structure of ethyl 1-(4-fluorobenzyl)-3-phenyl-1H-pyrazole-5-carboxylate, C19H17FN2O2

C19H17FN2O2, triclinic, P1̅ (no. 2), a = 7.8593(19) Å, b = 10.3322(18) Å, c = 10.9747(19) Å, α = 108.914(18)°, β = 92.931(3)°, γ = 99.544(3)°, V = 826.1(3) Å3, Z = 2, R gt(F) = 0.0431, wR ref(F 2) = 0.1170, T = 296.15 K.

Crystal structure of ethyl 1-(4-bromobenzyl)-3-phenyl-1H-pyrazole-5-carboxylate, C19H17BrN2O2

C19H17BrN2O2, triclinic, P1̅ (no. 2), a = 8.3979(11) Å, b = 10.4083(14) Å, c = 11.1696(15) Å, α = 69.270(2)°, β = 89.401(2)°, γ = 73.709(2)°, V = 872.1(2) Å3, Z = 2, R gt(F) = 0.0422, wR ref(F 2) = 0.1138, T = 296.15 K.

Crystal structure of 2-(1-benzyl-3-phenyl-1H-pyrazol-5-yl)-5-(4-nitrobenzylthio)-1,3,4-oxadiazole, C25H19N5O3S

C25H19N5O3S, monoclinic, P21/c (no. 14), a = 16.715(2) Å, b = 11.2677(15) Å, c = 12.6490(17) Å, β = 110.818(2)°, V = 2226.7(5) Å3, Z = 4, R gt(F) = 0.0424, wR ref(F 2) = 0.1037, T = 296 K.

Crystal structure of ethyl 1-benzyl-5-phenyl-1H-pyrazole-3-carboxylate, C19H18N2O2

C19H18N2O2, triclinic, P1̅ (no. 2), a = 9.832(2) Å, b = 10.590(2) Å, c = 17.794(3) Å, α = 77.080(3)°, β = 81.720(4)°, γ = 64.958(3)°, V = 1633.7(5) Å3, Z = 4, R gt(F) = 0.0634, wR ref(F 2) = 0.1964, T = 296 K.

Crystal structure of methyl 1-(4-fluorobenzyl)-3-phenyl-1H-pyrazole-5-carboxylate, C18H15FN2O2

C18H15FN2O2, triclinic, P1̅ (no. 2), a = 7.8272(8) Å, b = 9.6662(10) Å, c = 10.9834(12) Å, α = 107.859(2)°, β = 92.559(2)°, γ = 99.415(2)°, V = 776.31(14) Å3, Z = 2, R gt(F) = 0.0407, wR ref(F 2) = 0.1187, T = 296 K.

An efficient one-pot catalyzed synthesis of 2,5-disubstituted-1,3,4-oxadiazoles and evaluation of their antimicrobial activities

A facile and convenient one-pot catalyzed synthesis of 2,5-disubstituted-1,3,4-oxadiazole derivatives as efficient antimicrobial agents was described.

Synthesis, Crystal Structures and Xanthine Oxidase Inhibitory Activity of 2-(Benzylthio)-5-[1-(4-Fluorobenzyl)-3-Phenyl-1H-Pyrazol-5-Yl]-1,3,4-Oxadiazoles Derivatives

A synthetic route for the preparation of 2-(benzylthio)-5-[1-(4-fluorobenzyl)-3-phenyl-1H-pyrazol-5-yl]-1,3,4-oxadiazoles derivatives from ethyl 3-phenyl-1H-pyrazole-5-carboxylate has been developed. The configurations of the intermediate 1,3,4-oxadiazole-2-thione and 3-bromobenzylthio substituted 1,3,4-oxadiazole were determined by single crystal X-ray diffraction analysis. The in vitro xanthine oxidase inhibitory activity of these compounds was evaluated.