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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.

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.

Mitogen activated protein kinase (MAPK) signal transduction pathway has been proved to play an important role in tumorigenesis and cancer development. MEK inhibitor has been demonstrated significant clinical benefit for blocking MAPK pathway activation and possibly could block reactivation of the MAPK pathway at the time of BRAF inhibitor resistance. Twenty N-(benzyloxy)-1,3-diphenyl-1H-pyrazole-4-carboxamide derivatives have been designed and synthesized as MEK inhibitors, and their biological activities were evaluated. Among these compounds, compound 7b showed the most potent inhibitory activity with IC50 of 91nM for MEK1 and GI50 value of 0.26μM for A549 cells. The SAR analysis and docking simulation were performed to provide crucial pharmacophore clues that could be used in further structure optimization.

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.

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.

A series of novel Mannich base derivatives of flavone containing benzylamine moiety was synthesized using the Mannich reaction. The results of antifungal activity are not ideal, but its antifungal effect has a certain increase compared to flavonoids. After that, four bacteria were used to test antibacterial experiments of these compounds; compound 5g (MIC = 0.5, 0.125 mg/L) showed significant inhibitory activity against Staphylococcus aureus and Salmonella gallinarum compared with novobiocin (MIC = 2, 0.25 mg/L). Compound 5s exhibited broad spectrum antibacterial activity (MIC = 1, 0.5, 2, 0.05 mg/L) against four bacteria. The selected compounds 5g and 5s exhibit potent inhibition against Topo II and Topo IV with IC50 values (0.25–16 mg/L). Molecular docking model showed that the compounds 5g and 5s can bind well to the target by interacting with amino acid residues. It will provide some valuable information for the commercial antibacterial agents.

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.

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).

Succinate dehydrogenase (SDH) plays an important role in the Krebs cycle, which is considered as an attractive target for development of succinate dehydrogenase inhibitors (SDHIs) based on antifungal agents. Thus, in order to discover novel molecules with high antifungal activities, SDH as the target for a series of novel nicotinamide derivatives bearing substituted pyrazole moieties were designed and synthesised via a one-pot reaction.The biological assay data showed that compound 3 l displayed the most potent antifungal activity with ECThe study suggests that the pyrazole nicotinamide derivative 3 l may serve as a potential SDHI that can be used as a novel antifungal agent, and provides valuable clues for the further design and optimisation of SDH inhibitors. © 2016 Society of Chemical Industry.

An extract from the female sex gland of Semiothisa cinerearia attracted conspecific males in field tests. A major active component was isolated from the extract and identified by GC-MS, GC-IR and microchemical reactions as cis-3,4-epoxy-(Z,Z)-6. 9-heptadecadiene, which showed strong EAG response. Another minor yet important component was identified as (Z,Z,Z)-3,6,9-heptadecatriene.