Synthesis and bioactivities of novel pyrazole oxime derivatives containing a 1,2,3-thiadiazole moiety

Base-promoted anaerobic intramolecular cyclization synthesis of 4,5-disubstituted-1,2,3-thiadiazoles

An alkali-promoted, transition-metal-free and oxidant-free method to construct 4,5-disubstituted-1,2,3-thiadiazoles from N-tosylhydrazone-bearing thiocarbamates by employing a sustainable intramolecular reaction strategy has been developed.

Synthesis of New 1-Aryl-2-(3,5-dimethylpyrazol-1-yl)ethanone Oxime Ether Derivatives and Investigation of Their Cytotoxic Effects

In this study, 12 new 1-aryl-2-(3,5-dimethylpyrazol-1-yl)ethanone oxime ether derivatives were designed and synthesized to investigate their cytotoxic effects. The in vitro cytotoxic activities of the compounds were evaluated against cervix, colon, breast, glioma, neuroblastoma, and lung cancer cell lines, as well as a healthy cell line using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazo-lium bromide (MTT) assays with 5-fluorouracil (5-FU) as the reference compound. Compound 5f (IC50 = 5.13 µM) was found to be more effective than 5-FU (IC50 = 8.34 µM) in the C6 cancer cell line, and it had no cytotoxic effect on the L929 healthy cell line. Flow cytometry was used to investigate the mechanism of action of compound 5f on the cell cycle of the C6 cell line. The analysis showed that cell death was significantly due to apoptosis. These results indicate that compound 5f induces cell cycle arrest, and may be effective in treating glioma.

Photo-oxidative Ruthenium(II)-Catalyzed Formal [3 + 2] Heterocyclization of Thioamides to Thiadiazoles

An operationally simple and sustainable one-pot photo-oxidative formal [3 + 2] heterocyclization of β-ketothioamides with aryldiazonium salts catalyzed by Ru(bpy)₃Cl₂ has been realized to provide 2,4-disubstituted 5-imino-1,2,3-thiadiazoles in good to high yields under mild reaction conditions for the first time. The reaction proceeded via an α-phenylhydrazone adduct of thioamides leading to 1,2,3-thiadiazoles via N-S bond formation at room temperature. Notably, the products possess Z-stereochemistry with regard to the exocyclic C═N double bond at the 5-position of the ring.

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).

Design, synthesis, antibacterial evaluation, molecular docking and computational study of 4-alkoxy/aryloxyphenyl cyclopropyl methane oxime derivatives

A series of new 4-alkoxy/aryloxyphenyl cyclopropyl methane oxime derivatives 2(a-k) were synthesized and fully characterized by FT-IR, 1H-NMR, 13C-NMR and Mass spectrometry techniques. All the synthesized compounds 2(a-k) were assayed for in vitro antibacterial activity against a selected bacterial strain and the compound (2 h) and (2k) exerted excellent activity against Staphylococcus aureus, Escherichia coli and Salmonella typhi strains. The potency of inhibitors and possible interaction mechanism of synthetic oxime (2k) with 1GQN enzyme on Salmonella typhi was explored by molecular docking method. Amongst the all synthesized compounds, the quantum chemical calculations were done for Cyclopropyl(4-(pyridin-3-ylmethoxy)phenyl)methanone oxime (2k). The first hyperpolarizability calculation performed in different solvent such as CHCl₃, CH₂Cl₂ and DMSO and compared to the reference compound urea. In addition, natural bond orbital analysis (NBO), local reactivity descriptors, thermodynamic properties, Mulliken charges, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were explored using theoretical calculations.

Thiadiazole derivatives as anticancer agents

In spite of substantial progress made toward understanding cancer pathogenesis, this disease remains one of the leading causes of mortality. Thus, there is an urgent need to develop novel, more effective anticancer therapeutics. Thiadiazole ring is a versatile scaffold widely studied in medicinal chemistry. Mesoionic character of this ring allows thiadiazole-containing compounds to cross cellular membrane and interact strongly with biological targets. Consequently, these compounds exert a broad spectrum of biological activities. This review presents the current state of knowledge on thiadiazole derivatives that demonstrate in vitro and/or in vivo efficacy across the cancer models with an emphasis on targets of action. The influence of the substituent on the compounds' activity is depicted. Furthermore, the results from clinical trials assessing thiadiazole-containing drugs in cancer patients are summarized.

Synthesis, Insecticidal Evaluation, and 3D-QASR of Novel Anthranilic Diamide Derivatives Containing N-Arylpyrrole as Potential Ryanodine Receptor Activators

To cope with the global food shortage and insect pest, there is an urgent need to discover new pesticides with novel modes of actions. Ryanodine receptor (RyR) insecticides showed great promise in integrated pest management. Herein, we report the synthesis of novel anthranilic diamide derivatives incorporating pyrrole moieties targeting at insect RyRs. The structures were confirmed by ¹H NMR, ¹³C NMR, ¹⁹F NMR, and high-resolution mass spectrometry. The preliminary bioassay results indicated that most of the title compounds showed good to excellent insecticidal activities against the oriental armyworm (Mythimna separata) and diamondback moth (Plutella xylostella). For the oriental armyworm, Ij displayed the same level of larvicidal activity as the positive control chlorantraniliprole, with an LC₅₀ value of 0.21 mg/L. For the diamondback moth, In, Io, Ip, and Iq exhibited higher insecticidal activities than chlorantraniliprole. In particular, In had 50% larvicidal activity at 0.00001 mg/L. The calcium imaging technique was applied to study the effect of Ij, In, and Ip on the intracellular calcium ion concentration ([Ca²⁺]_i) in central neurons isolated from the oriental armyworm. The results indicated that the tested compounds, such as chlorantraniliprole, could activate the insect RyRs. Furthermore, comparative molecular field analysis and density functional theory calculations were carried out to study the structure-activity relationship.

Design, Synthesis, and Biological Evaluation of Novel Thiazolyl Substituted Bis-pyrazole Oxime Derivatives with Potent Antitumor Activities by Selectively Inducing Apoptosis and ROS in Cancer Cells

BACKGROUND

A large number of pyrazole derivatives have different biological activities such as anticancer, antimicrobial, anti-inflammatory, analgesic and antiepileptic activity. Among them, pyrazole oximes have attracted much attention due to their potential pharmacological activities, particularly anticancer activities.

OBJECTIVE

Our goal is to synthesize novel thiazolyl substituted bis-pyrazole oxime derivatives with potent antitumor activities by selectively inducing apoptosis and Reactive Oxygen Species (ROS) accumulation in cancer cells.

METHODS

Eighteen bis-pyrazole oximes were synthesized by conjugating thiazolyl substituted pyrazoles with pyrazoxime. The target compounds were characterized by 1HNMR, 13C NMR, and HRMS, and screened for their antiproliferative activity against four cancer cells in MTT assay. The most potent compound was examined for its inhibitory effect and ROS accumulation in both cancer cells HCT116 and normal intestinal epithelial cells CCD841. Finally, the most potent compound was further evaluated for its apoptotic induction by flow cytometry analysis and immunoblot analysis of apoptosis-related proteins and DNA damage proteins.

RESULTS

Most compounds displayed potent antiproliferative activity against four cancer cell lines in vitro, displaying potencies superior to 5-FU. In particular, the most potent compound 13l selectively inhibited proliferation of colorectal cancer HCT116 cells but not normal colon CCD841 cells. Furthermore, compound 13l also selectively promoted intracellular ROS accumulation in HCT116 which was involved in 13l inhibition of cancer cell proliferation and induction of cell apoptosis. Finally, compound 13l also dose-dependently induced cancer cell apoptosis by regulating apoptotic and DNA damage related proteins expressions.

CONCLUSION

Our synthetic bis-pyrazole oxime derivatives possess potent antitumor activities by selectively inducing apoptosis and ROS accumulation in cancer cells, which may hold great promise as therapeutic agents for the treatment of human cancers.

Discovery of Novel Isothiazole, 1,2,3-Thiadiazole, and Thiazole-Based Cinnamamides as Fungicidal Candidates

A series of isothiazole, 1,2,3-thiadiazole, and thiazole-based cinnamamide morpholine derivatives were rationally designed, synthesized, characterized, and evaluated for their fungicidal activities. Bioassay indicated that a combination of 3,4-dichloroisothiazole active substructures with cinnamamide morpholine lead to significant improvement of in vivo antifungal activities of the target compounds; among them, compound 5a exhibited good fungicidal activity against Pseudoperonspera cubensis in vivo with an inhibition rate of 100% at 100 μg/mL. A field experiment indicated that the difference of efficacy between 5a (75.9%) and dimethomorph (77.1%) at 37.5 g ai/667 m² was not significant; and 5a also exhibited good activity against Botrytis cinerea by triggering accumulation of PAL and NPR1 defense-related gene expression and the defense associated enzyme phenylalanine ammonia-lyase (PAL) expression on cucumber, rather than direct inhibition. These findings strongly supported that 3,4-dichloroisothiazole containing cinnamamide morpholine 5a not only showed good fungicidal activity against P. cubensis but also exhibited plant innate immunity stimulation activity as a promising fungicide candidate with both fungicidal activity and systemic acquired resistance.

I2/CuCl2-promoted one-pot three-component synthesis of aliphatic or aromatic substituted 1,2,3-thiadiazoles

An efficient I₂/CuCl₂-promoted one-pot three-component strategy for the construction of 1,2,3-thiadiazoles from aliphatic- or aromatic-substituted methyl ketones, p-toluenesulfonyl hydrazide, and potassium thiocyanate has been developed. Simple and commercially available starting materials, a broad substrate scope, and excellent functional group tolerability make this strategy practical for applications. Furthermore, 1,2,3-thiadiazole synthesis was realized by using potassium thiocyanate as an odorless sulfur source.

A new exploration towards aminothiazolquinolone oximes as potentially multi-targeting antibacterial agents: Design, synthesis and evaluation acting on microbes, DNA, HSA and topoisomerase IV

This work did a new exploration towards aminothiazolquinolone oximes as potentially multi-targeting antimicrobial agents. A class of novel hybrids of quinolone, aminothiazole, piperazine and oxime fragments were designed for the first time, conveniently synthesized as well as characterized by ¹H NMR, ¹³C NMR and HRMS spectra. Biological activity showed that some of the synthesized compounds exhibited good antimicrobial activities in comparison with the reference drugs. Especially, O-methyl oxime derivative 10b displayed excellent inhibitory efficacy against MRSA and S. aureus 25923 with MIC values of 0.009 and 0.017 mM, respectively. Further studies indicated that the highly active compound 10b showed low toxicity toward BEAS-2B and A549 cell lines and no obvious propensity to trigger the development of bacterial resistance. Quantum chemical studies have also been conducted and rationally explained the structural features essential for activity. The preliminarily mechanism exploration revealed that compound 10b could not only exert efficient membrane permeability by interfering with the integrity of cells, bind with topoisomerase IV-DNA complex through hydrogen bonds and π-π stacking, but also form a steady biosupramolecular complex by intercalating into DNA to exert the efficient antibacterial activity. The supramolecular interaction between compound 10b and human serum albumin (HSA) was a static quenching, and the binding process was spontaneous, where hydrogen bonds and van der Waals force played vital roles in the supramolecular transportation of the active compound 10b by HSA.

Novel Synthesis and Biological Evaluation of the First Pyrazole Thioglycosides as Pyrazofurin Analogues

This study reports a novel and efficient method for the synthesis of the first reported novel class of pyrazole thioglycosides 6a-h. These series of compounds were designed through the reaction of sodium 2-cyano-3-oxo-3-(4-substitutedphenylamino)prop-1-ene-1,1-bis(thiolate) salts 2 with hydrazine hydrate in ethanol at room temperature to give the corresponding sodium 5-amino-4-(substitutedphenylcarbamoyl)-1H-pyrazole-3-thiolates 3a-d. The latter compounds were treated with protected α-D-gluco- and galacto-pyranosyl bromides 4a,b in DMF at ambient temperature to give in a high yields the corresponding pyrazole thioglycosides 6a-h. Treatment of pyrazole salts 3a-d with hydrochloric acid at amobient temperature afforded the corresponding 3-mercaptopyrazole derivatives 5. The latter compounds were treated with peracetylated sugars 4 in sodium hydride in ethanol at ambient temperature to tolerate the S-glycosyl 6a-h compounds. Ammonolysis of the pyrazole thioglycosides 6a-h afforded the corresponding free thioglycosides 7a-h. The toxicity and antitumor activities of the synthesized compounds were studied.

The Good, the Bad, and the Ugly: "HiPen", a New Dataset for Validating (S)QM/MM Free Energy Simulations

Indirect (S)QM/MM free energy simulations (FES) are vital to efficiently incorporating sufficient sampling and accurate (QM) energetic evaluations when estimating free energies of practical/experimental interest. Connecting between levels of theory, i.e., calculating Δ A l o w → h i g h , remains to be the most challenging step within an indirect FES protocol. To improve calculations of Δ A l o w → h i g h , we must: (1) compare the performance of all FES methods currently available; and (2) compile and maintain datasets of Δ A l o w → h i g h calculated for a wide-variety of molecules so that future practitioners may replicate or improve upon the current state-of-the-art. Towards these two aims, we introduce a new dataset, "HiPen", which tabulates Δ A g a s M M → 3 o b (the free energy associated with switching from an M M to an S C C - D F T B molecular description using the 3ob parameter set in gas phase), calculated for 22 drug-like small molecules. We compare the calculation of this value using free energy perturbation, Bennett's acceptance ratio, Jarzynski's equation, and Crooks' equation. We also predict the reliability of each calculated Δ A g a s M M → 3 o b by evaluating several convergence criteria including sample size hysteresis, overlap statistics, and bias metric ( Π ). Within the total dataset, three distinct categories of molecules emerge: the "good" molecules, for which we can obtain converged Δ A g a s M M → 3 o b using Jarzynski's equation; "bad" molecules which require Crooks' equation to obtain a converged Δ A g a s M M → 3 o b ; and "ugly" molecules for which we cannot obtain reliably converged Δ A g a s M M → 3 o b with either Jarzynski's or Crooks' equations. We discuss, in depth, results from several example molecules in each of these categories and describe how dihedral discrepancies between levels of theory cause convergence failures even for these gas phase free energy simulations.

Design, Synthesis, and Biological Activities of Novel Pyrazole Oxime Compounds Containing a Substituted Pyridyl Moiety

In this paper, in order to find novel biologically active pyrazole oximes, a series of pyrazole oxime compounds bearing a substituted pyridyl unit were prepared. Bioassays showed that some target compounds were found to have good acaricidal activity against Tetranychus cinnabarinus at a concentration of 500 μg/mL, compound 9q especially displayed potent acaricidal activity against T. cinnabarinus when the concentration was reduced to 100 μg/mL. Interestingly, most target compounds possessed excellent insecticidal activities against Oriental armyworm at 500 μg/mL. Moreover, some compounds were active against Aphis medicaginis and Nilaparvata lugens at 500 μg/mL. Additionally, compounds 9b, 9g, 9l, 9p, 9q, 9r, 9s, 9t, 9u, and 9v displayed significant antiproliferative activities against HepG2 cells with IC₅₀ values of 1.53-17.27 μM, better than that of the control 5-fluorouracil (IC₅₀ = 35.67 μM).

Synthesis, Crystal Structure, and DFT Study of Ethyl 1-(2-(Hydroxyimino)-2-phenylethyl)-3-phenyl-1H-pyrazole-5-carboxylate

The crystal structure of ethyl 1-(2-(hydroxyimino)-2-phenylethyl)-3-phenyl-1H-pyrazole-5-carboxylate has been determined by X-ray single crystal diffraction. The crystal of the title compound is the monoclinic space group P2/c with unit cell parameters of a=8.634(2) Å, b=9.616(2) Å, c=22.190(3) Å, β=99.2652°, V=1818.3(4) Å3, and Z=4. The dihedral angles formed by the planes of the central pyrazole ring and the adjacent benzene rings are 73.60(7)° and 3.55(7)°, respectively. The combination of the weak intermolecular C-H⋯O and N-H⋯O hydrogen-bonding interactions stabilizes the crystal packing. The geometries of its Z and E isomers and the corresponding transition state (TS), as well as the dimer of its Z isomer, are optimized using the B3LYP hybrid functional coupled with def-TZVP triple-zeta polarized basis set. The bond angles and bond lengths of the optimized structure of Z dimer are very consistent with those of its single crystal parameters. Double-hybrid functional PWPB95-D3 in combination with very highly accurate basis set def2-QZVP is employed to evaluate accurate energy of each isomer and TS. The calculated equilibrium constant between Z and E isomers corresponds to the [Z]/[E] ratio of 4.29. Mulliken atomic charges and electrostatic potential (ESP) on molecular van der Waals (vdW) surface are calculated in order to study and predict the intermolecular interactions. The molecular total energies and frontier orbital analysis are also discussed.