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Inspired by commercially established fluxapyroxad as the lead compound of novel efficient antifungal ingredients, novel pyrazole carboxylate derivatives containing a flexible thiazole backbone were successfully designed, synthesized, and detected for their in vitro and in vivo biological activities against eight agricultural fungi. The antifungal bioassay results showed that compound 24 revealed excellent bioactivities against Botrytis cinerea and Sclerotinia sclerotiorum, with median effective concentrations (EC50) of 0.40 and 3.54 mg/L, respectively. Compound 15 revealed remarkable antifungal activity against Valsa mali, with an EC50 value of 0.32 mg/L. For in vivo fungicide control against B. cinerea and V. mali, compounds 3 and 24 at 25 mg/L, respectively, displayed prominent efficacy on cherry tomatoes and apple branches. Molecular docking results demonstrated that compound 15 could form an interaction with several crucial residues of succinate dehydrogenase (SDH), and the in vitro enzyme assay indicated that the target compound 15 displayed an inhibitory effect toward SDH, with an IC50 value of 82.26 μM. The experimental results indicated that phenyl pyrazole carboxylate derivatives displayed a weak antifungal property and low activity compared to the other title substituent pyrazole carboxylate derivatives. Compounds 3, 15, and 24 are promising antifungal candidates worthy of further fungicide development due to their prominent effectiveness.

BACKGROUND To promote the discovery and development of new fungicide with novel scaffolds or modes of action, a series of novel 5-(2-chloroethyl)-1-phenyl-6-(pyridin-4-yl)-1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-one derivatives were synthesized, and evaluated for their antifungal activities. RESULTS The bioassay data showed that compound 8IIId (EC50 = 1.93 mg L-1 ) is superior to boscalid (EC50 = 6.71 mg L-1 ) against Valsa mali. We introduced chiral groups on the structure of 8IIId, and two chiral configurations were respectively synthesized, which are 8Vc and 8Vd. Surprisingly, 8Vc showed significant antifungal activities against Valsa mali and Physalospora piricola with EC50 values of 0.22 and 0.55 mg L-1 . Physiological and biochemical studies showed that the primary action mechanism of compound 8Vc on Valsa mali may involve changing mycelial morphology and increasing cell membrane permeability. CONCLUSION These results demonstrated that 8Vc could be further modified as fungicide and provided a valuable reference for antifungal agents with pyrazolo[3,4-d]pyrimidin-4-one skeleton. © 2021 Society of Chemical Industry.

The design and synthesis of novel multi-substituted benzo-indole pyrazole Schiff base derivatives of potent DNA gyrase inhibitory activity were the main aims of this study. All the novel synthesized compounds were examined for their antibacterial activities against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella. In addition, we selected 20 compounds for the in vitro antibacterial activities assay of 6 drug-resistant bacteria strains. The result revealed compound 8I-w exhibited excellent antibacterial activity against 4 drug-resistant E. coli bacteria strains with IC50 values of 7.0, 17.0, 13.5, and 1.0 μM, respectively. In vitro enzyme inhibitory assay showed that compound 8I-w displayed potent inhibition against DNA gyrase with IC50 values of 0.10 μM. The molecular docking model indicated that compounds 8I-w can bind well to the DNA gyrase by interacting with various amino acid residues. This study demonstrated that the compound 8I-w can act as the most potent DNA gyrase inhibitor in the reported series of compounds and provide valuable information for the commercial DNA gyrase inhibiting bactericides.

Hit, Lead & Candidate Discovery To discover succinate dehydrogenase inhibitors with a novel structure, we introduced cinnamic acid structure to optimize the lead structure 1 and synthesized four series of cinnamon-pyrazole carboxamide derivatives. The bioassay data showed that compounds (E)-N-(1-[4-chlorophenyl]-4-cyano-1H-pyrazol-5-yl)-3-(2-fluorophenyl) acrylamide (5III-d) and (E)-3-(2-chlorophenyl)-N-(1-[4-chlorophenyl]-4-cyano-1H-pyrazol-5-yl) acrylamide (5III-f) showed the significant antifungal activity against three fungi. In addition, 5III-d and 5III-f exhibited the excellent inhibitory effect against succinate dehydrogenase (SDH) enzymes with IC50 values ranging from 19.4 to 28.7 μM. The study demonstrates that the chlorine substituent group is present on both the phenyl and pyrazole rings that have a very good effect on the antifungal effect, and the compounds 5III-d and 5III-f can act as potential SDH inhibitors (SDHI) and throw a sprat for a new generation of SDHI.

Many pyrazole derivatives were reported to exhibit highly activity towards tobacco mosaic virus (TMV). In this work, an optimized pyrazole Schiff base scaffold was designed and introduced to derive novel potential TMV inhibitors. Thirty-six compounds were synthesized, characterized by elemental analysis, mass spectra and nuclear magnetic resonance (NMR) spectroscopy and evaluated by biological experiments. The bioassay results showed that some of the synthesized compounds exhibited excellent anti-TMV activities. Especially, 5-chloro-3-methyl-1H-pyrazole contained compound 4j showed ningnanmycin comparable inhibitory activity and can be considered as potential anti-TMV candidate agent. With molecular docking, compound 4j insert into nucleotide sequence (GAAGUU) of OriRNA stably which revealed nucleotide could be a target of these compounds.

In this work, a total of 36 novel 5-(nicotinamido)-1-phenyl-1H-pyrazole-4-carboxylic acid derivatives were designed and synthesized successfully by introducing a carboxyl group based on the N-(1-(4-chlorophenyl)-4-cyano-1H-pyrazol-5-yl)-6-methoxynicotinamide. Among them, the growth inhibition assays on agar plates showed that compound 5IV-d(5-(2-chloronicotinamido)-1-(p-tolyl)-1H-pyrazole-4-carboxylic acid) exhibited the significant antifungal activity against four important fruit and main crop disease fungi (i.e., Valsa mali Miyabe et Yamada, Botryosphaeria dothidea, Helminthosporium maydis and Rhizoctonia cerealis) with EC50 values of 22.6, 14.5, 17.6 and 18.2 μM, respectively. In addition, 5IV-d showed the excellent inhibitory effect against SDH enzymes with IC50 values ranging from 9.4 to 15.6 μM. In vivo bioassay and molecular docking were applied to explore the potential in practical application and combination of modified structure and SDH. The results of structure-activity relationships indicates that the methoxy substitution at the benzene ring attached to the pyrazole ring and a wide variety of substituents could be responsible for the promising antifungal efficacy of the designed compounds. This study demonstrated that the compound 5IV-d can act as the most potent SDH inhibitor in the reported series of compounds.

To develop new antibacterial agents, a series of novel triazole-containing pyrazole ester derivatives were designed and synthesized and their biological activities were evaluated as potential topoisomerase II inhibitors. Compound 4d exhibited the most potent antibacterial activity with Minimum inhibitory concentration (MIC) alues of 4 &micro, g/mL, 2 &micro, g/mL, 4 &micro, g/mL, and 0.5 &micro, g/mL against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella gallinarum, respectively. The in vivo enzyme inhibition assay 4d displayed the most potent topoisomerase II (IC50 = 13.5 &micro, g/mL) and topoisomerase IV (IC50 = 24.2 &micro, g/mL) inhibitory activity. Molecular docking was performed to position compound 4d into the topoisomerase II active site to determine the probable binding conformation. In summary, compound 4d may serve as potential topoisomerase II inhibitor.

The identification of novel Topoisomerase II (Topo II) inhibitors is one of the most attractive directions in the field of bactericide research and development. In our ongoing efforts to pursue the class of inhibitors, six series of 70 novel coumarin-pyrazole carboxamide derivatives were designed and synthesized. As a result of the evaluation against four destructive bacteria, including Staphylococcus aureus, Listeria monocytogenes, Escherichia coli and Salmonella. Compound 8III-k (MIC = 0.25 mg/L) showed considerable inhibitory activity than ciprofloxacin (MIC = 0.5 mg/L) against Escherichia coli and 8V-c (MIC = 0.05 mg/L) exhibited excellent antibacterial activity than ciprofloxacin (MIC = 0.25 mg/L) against Salmonella. The selected compounds (8III-k, 8V-c and 8V-k) exhibit potent inhibition against Topo II and Topo IV with IC50 values (9.4–25 mg/L). Molecular docking model showed that the compounds 8V-c and 8V-k can bind well to the target by interacting with amino acid residues. It will provide some valuable information for the commercial Topo II inhibiting bactericides.

Acetohydroxy acid synthase (AHAS; EC 2.2.1.6, also referred to as acetolactate synthase, ALS) has been considered as an attractive target for the design of herbicides. In this work, an optimized pyrazole sulfonamide base scaffold was designed and introduced to derive novel potential AHAS inhibitors by introducing a pyrazole ring in flucarbazone. The results of in vivo herbicidal activity evaluation indicates compound 3b has the most potent activity with rape root length inhibition values of 81% at 100 mg/L, and exhibited the best inhibitory ability against Arabidopsis thaliana AHAS. With molecular docking, compound 3b insert into Arabidopsis thaliana AHAS stably by an H-bond with Arg377 and cation-π interactions with Arg377, Trp574, Tyr579. This study suggests that compound 3b may serve as a potential AHAS inhibitor which can be used as a novel herbicides and provides valuable clues for the further design and optimization of AHAS inhibitors.

A series of novel (E)-1,3-diphenyl-1H-pyrazole derivatives containing O-benzyl oxime moiety were firstly synthesized and their immunosuppressive activities were evaluated. Among all the compounds, 4n exhibited the most potent inhibitory activity (IC50 = 1.18 μM for lymph node cells and IC50 = 0.28 μM for PI3Kγ), which was comparable to that of positive control. Moreover, selected compounds were tested for their inhibitory activities against IL-6 released in ConA-simulated mouse lymph node cells, 4n exhibited the most potent inhibitory ability. Furthermore, in order to study the preliminary mechanism of the compounds with potent inhibitory activity, the RT-PCR experiment was performed to assay the effect of selected compounds on mRNA expression of IL-6. Among them, compound 4n strongly inhibited the expression of IL-6 mRNA.

Acetylcholinesterase (AChE) is a key enzyme which present in the central nervous system of living organisms. Organophosphorus pesticides (OPs) that serve as insecticides are AChE inhibitors which have been used widely in agriculture. A series of novel OPs containing pyrazole moiety have been designed and synthesized. The biological evaluation indicated compound 4e appeared 81% larvicidal activity against Plutella xylostella at the concentration of 0.1 mg/L and the inhibition of AChE by compound 4e was distinctly enhanced with the increasing doses. Molecular docking of compound 4e into the three dimensional X-ray structure of the Drosophila melanogaster AChE (DmAChE, PDB code: 1QO9) was carried out utilizating the Discovery Studio (DS), the binding model revealed that the title structure was tightly embedded in the binding sites of DmAChE. Therefore, we suggest that compound 4e may serve as a novel AChE inhibitor that can be utilized as a new insecticidal drug.

Insect ryanodine receptor is one of the promising targets for the development of novel insecticides. In order to search for potent insecticides targeting the ryanodine receptor (RyR), a series of novel diphenyl-1H-pyrazole derivatives with cyano substituent were designed and synthesized. Their insecticidal activities against diamondback moth (Plutella xylostella) indicated that most of the compounds showed moderate to high activities at the four concentrations. Among these compounds, N-(4-cyano-1-(4-fluorophenyl)-1H-pyrazol-5-yl)-1-(4-fluorophenyl)-3-phenyl-1H-pyrazole-4-carboxamide (5g) showed 84% larvicidal activity against Plutella xylostella at the concentration of 0.1 mg L−1. Molecular docking showed the predicted binding mode between 5g and protein receptor, which could suggest that the title compounds were the possible activators of insect RyR.

A series of novel pyrazole amide derivatives 3a–3p which take TMV PC protein as the target has been designed and synthesized by the reactions of 5-chloro-1-aryl-3-methyl-1H-pyrazole-4-carboxylic acids with 5-amino-1-aryl-1H-pyrazole-4-carbonitriles. All the compounds were characterized by 1H-NMR, mass spectroscopy and elemental analysis. Preliminary bioassays indicated that all the compounds acted against the tobacco mosaic virus (TMV) with different in vivo and in vitro modes at 500 μg/mL and were found to possess promising activity. Especially, compound 3p showed the most potent biological activity against tobacco mosaic virus (TMV) compared to ningnanmycin, and a molecular docking study was performed and the binding model revealed that the pyrazole amide moiety was tightly embedded in the binding sites of TMV PC (PDB code: 2OM3).

It was discovered that a number of cyclin dependent kinase inhibitors containing the pyrazole core structure exhibited high inhibitory potency against broad-range CDKs and corresponding anti-proliferative activities. This information guided us to design and synthesize a series of 1,3-diphenyl-N-(phenylcarbamothioyl)-1H-pyrazole-4-carboxamide derivatives (5a–10d), and evaluate their biological activities as CDKs inhibitors. Among all the synthesized compounds, compound 10b inhibited CDK2 with an IC50 value of 25 nM, counteracting tumor cell proliferation of three cancer cell lines (H460, MCF-7, A549) in the micromolar range (from 0.75 μM to 4.21 μM), In addition, flow cytometry indicated that compound 10b could induce cycle G0/G1 phase arrest in A549 cells with a dose dependent. Taken together, compound 10b could be selected for further preclinical evaluation.

Due to the rising incidence and lack of effective treatments, malignant melanoma is the most dangerous form of skin cancer, so that new treatment strategies are urgently needed. Several recent developments indicate that the V600E mutant BRAF (BRAF(V600E) ) is a validated target for antimelanoma-drug development. Based on in silico screening results, a series of novel pyrazole derivatives has been designed, synthesized, and evaluated in vitro for their inhibitory activities against BRAF(V600E) melanoma cells. Compound 3d exhibited the most potent inhibitory activity with an IC50 value of 0.63 μM for BRAF(V600E) and a GI50 value of 0.61 μM for mutant BRAF-dependent cells. Furthermore, the QSAR modeling and the docking simulation of inhibitor analogs provide important pharmacophore clues for further structural optimization.

There is an accumulating body of experimental evidences validating oncogenic BRAF(V600E) as a therapeutic target and offering opportunities for anti-melanoma drug development. Encouraged by the positive results of pyrazole derivatives as BRAF(V600E) inhibitors, we sought to design diverse novel potential BRAF(V600E) inhibitors as antitumor agents based on pyrazole skeleton. In silico and in vitro screening of our designed pyrazole derivatives has identified Hit 1 as BRAF(V600E) inhibitor. Based on its structure and through further structure modification, compound 25, which exhibited the most potent inhibitory activity with an IC(50) value of 0.16 μM for BRAF(V600E) and GI(50) value of 0.24 μM for mutant BRAF-dependent melanoma cells, was obtained. The 3D-QSAR models and the molecular docking simulation were introduced to analyze the structure-activity relationship.