Synthesis, crystal structure, herbicidal activities and 3D-QSAR study of some novel 1,2,4-triazolo[4,3-a]pyridine derivatives

Combining QSAR techniques, molecular docking, and molecular dynamics simulations to explore anti-tumor inhibitors targeting Focal Adhesion Kinase

Focal Adhesion Kinase (FAK) is an important target for tumor therapy and is closely related to tumor cell genesis and progression. In this paper, we selected 46 FAK inhibitors with anticancer activity in the pyrrolo pyrimidine backbone to establish 3D/2D-QSAR models to explore the relationship between inhibitory activity and molecular structure. We have established two ideal models, namely, the Topomer CoMFA model (q 2 = 0.715, r 2 = 0.984) and the Holographic Quantitative Structure-Activity Relationship (HQSAR) model (q 2 = 0.707, r 2 = 0.899). Both models demonstrate excellent external prediction capabilities.Based on the QSAR results, we designed 20 structurally modified novel compounds, which were subjected to molecular docking and molecular dynamics studies, and the results showed that the new compounds formed many robust interactions with residues within the active pocket and could maintain stable binding to the receptor proteins. This study not only provides a powerful screening tool for designing novel FAK inhibitors, but also presents a series of novel FAK inhibitors with high micromolar activity that can be used for further characterization. It provides a reference for addressing the shortcomings of drug metabolism and drug resistance of traditional FAK inhibitors, as well as the development of novel clinically applicable FAK inhibitors.Communicated by Ramaswamy H. Sarma.

Spectroscopic and optical properties of 1,2,4-triazolo[4,3-a]pyridin-3(2H)-one as a component of herbicides

The herbicides azafenidin [(2-(2,4-dichloro-5-prop-2-ynoxyphenyl)-5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyridin-3-one)] and flumetsulam [(N-(2,6-difluorophenyl)-5-methyl-[1,2,4]triazolo[1,5-a]pyrimidine-2-sulfonamide)] were subjected to IR, Raman, UV-Vis and emission studies. As triazolopyridine is the most prominent and active component of these herbicides, this molecule was characterised by XRD studies, FTIR, Raman, UV-Vis and emission spectra. The experimental data were compared to the results of the DFT quantum chemical calculations carried out for its optimised structure, IR intensities and Raman activities, HOMO-LUMO transitions, and energies of the singlet and triplet states. The characteristics for triazolopyridine quantities were used in the analysis of the studied herbicides.

Herbicidal Activity of Beflubutamid Analogues as PDS Inhibitors and SAR Analysis and Degradation Dynamics in Wheat

In this work, a series of beflubutamid (BF) analogues' postemergent herbicidal activity was evaluated, and the structure-activity relationship (SAR) was discussed. At a dosage of 300 g ai/ha, compounds (Rac)-6h and (Rac)-6q showed excellent herbicidal activity against Amaranthus retroflexus, Abutilon theophrasti, and Medicago sativa, with inhibition rates of 90, 100, and 80% and 100, 100, and 100%, respectively, comparable to that of commercial herbicide BF, which showed inhibition rates of 90, 100, and 100%, respectively. Notably, at dosages of 150 and 300 g ai/ha, the chiral compounds (S)-6h and (S)-6q exhibited higher herbicidal activities than their racemates. Molecular docking results indicated that compounds (S)-BF and (S)-6h have stronger binding affinities with Oryza sativa phytoene desaturase (OsPDS), resulting in a higher herbicidal activity. Additionally, the degradation dynamics half-life of (S)-BF in wheat was determined to be 77.02 h. Consequently, compounds (S)-6h and (S)-6q are promising lead candidates for the development of highly effective herbicides.

3D-QSAR-Based Molecular Design to Discover Ultrahigh Active N-Phenylpyrazoles as Insecticide Candidates

Three-dimensional quantitative structure-activity relationship (3D-QSAR) is one of the most important and effective tools to direct molecular design in new pesticide development. Chlorantraniliprole is an anthranilic diamide ryanodine receptor (RyR) agonist with ultrahigh activity, high selectivity, and mammalian safety. To continue our studies on new insecticide development, here, we designed new insecticidal N-phenylpyrazoles by using 3D-QSAR of chlorantraniliprole analogues as a guide. Most of the target compounds synthesized exhibited medium to excellent activity against Mythimna separata, Plutella xylostella, and Spodoptera frugiperda. Compounds III b and III y showed similar activity against M. separata as chlorantraniliprole (LC₅₀ values: 0.21, 0.25, and 0.16 μg mL^-1 respectively). Compounds III b exhibited a 3-fold higher potency against P. xylostella than chlorantraniliprole. For S. frugiperda, the potency of III a and III b was 2.9 and 2.0 times higher than that of the positive control, respectively. The mode of action of the title compounds was validated by calcium imaging experiments and molecular docking using their target RyRs. III b can dock well with mutated P. xylostella RyRs, implying a potentially lower cross-resistance risk as compared with commercial RyR agonists. Density functional theory calculations suggested the feasibility of higher potency with the structural modifications. Compound III b was found to be an ultrahigh active insecticidal candidate with a broad spectrum for integrated pest management.

Design, Synthesis, Herbicidal Activity, and Molecular Docking Study of 2-Thioether-5-(Thienyl/Pyridyl)-1,3,4-Oxadiazoles as Potent Transketolase Inhibitors

Transketolase (TK) has been regarded as a new target for the development of novel herbicides. In this study, a series of 2-thioether-5-(thienyl/pyridyl)-1,3,4-oxadiazoles were designed and synthesized based on TK as the new target. The preliminary bioassay results indicated that compounds 4l and 4m displayed the best herbicidal activities against Amaranthus retroflexus (AR) and Digitaria sanguinalis (DS), with the inhibition exceeding 90% at 100-200 mg/L in vitro. Moreover, they also displayed higher postemergence herbicidal activities (90% control) against AR and DS than all of the positive controls at 45-90 g [active ingredient (ai)]/ha in a greenhouse. Notably, compounds 4l and 4m showed a broad spectrum of weed control at 90 g ai/ha. More significantly, compound 4l exhibited good crop selectivity against maize at 90 g ai/ha. Both fluorescent binding experiments and molecular docking analyses indicated that compounds 4l and 4m exhibited strong TK inhibitory activities with superior binding affinities than the others. Preliminary mechanism studies suggested that they might exert their TK inhibitory effects by occupying the active cavity of At TK and forming more strong interactions with amino acids in the active site. Taken together, these results suggested that compound 4l was a potential herbicide candidate for weed control in maize fields targeting TK.

The Structural and Optical Properties of 1,2,4-Triazolo[4,3-a]pyridine-3-amine

The structural and spectroscopic properties of a new triazolopyridine derivative (1,2,4-triazolo[4,3-a]pyridin-3-amine) are described in this paper. Its FTIR spectrum was recorded in the 100–4000 cm⁻¹ range and its FT-Raman spectrum in the range 80–4000 cm⁻¹. The molecular structure and vibrational spectra were analyzed using the B3LYP/6-311G(2d,2p) approach and the GAUSSIAN 16W program. The assignment of the observed bands to the respective normal modes was proposed on the basis of PED calculations. XRD studies revealed that the studied compound crystallizes in the centrosymmetric monoclinic space group P2₁/n with eight molecules per unit cell. However, the asymmetric unit contains two 1,2,4-triazolo[4,3-a]pyridin-3-amine molecules linked via N–H⋯N hydrogen bonds with a R₂²(8) graph. The stability of the studied molecule was considered using NBO analysis. Electron absorption and the luminescence spectra were measured and discussed in terms of the calculated singlet, triplet, HOMO and LUMO electron energies. The Stokes shifts derived from the optical spectra were equal to 9410 cm⁻¹ for the triazole ring and 7625 cm⁻¹ for the pyridine ring.

Synthesis, Crystal Structure, Herbicidal Activity, and SAR Study of Novel N-(Arylmethoxy)-2-chloronicotinamides Derived from Nicotinic Acid

Nicotinic acid, also known as niacin, is a natural product, which is widely found in plants and animals. To discover novel natural-product-based herbicides, a series of N-(arylmethoxy)-2-chloronicotinamides were designed and synthesized. Some of the new N-(arylmethoxy)-2-chloronicotinamides exhibited excellent herbicidal activity against Agrostis stolonifera (bentgrass) at 100 μM. Compound 5f (2-chloro-N-((3,4-dichlorobenzyl)oxy)nicotinamide) possessed excellent herbicidal activity against Lemna paucicostata (duckweed), with an IC₅₀ value of 7.8 μM, whereas the commercial herbicides clomazone and propanil had values of 125 and 2 μM, respectively. The structure-activity relationships reported in this paper could be used for the development of new herbicides against monocotyledonous weeds.

The crystal structure of (E)-3-chloro-2-(2-(2-fluorobenzylidene)hydrazinyl)pyridine, C12H9ClFN3

C12H9ClFN3, monoclinic, C2/c (no. 15), a = 24.713(13) Å, b = 15.459(13) Å, c = 17.507(12) Å, β = 17.515(11)°, V = 4742(6) Å3, Z = 16, R gt (F) = 0.0530, wR ref (F 2) = 0.1161, T = 113(2) K.

Design, step-economical diversity-oriented synthesis of an N-heterocyclic library containing a pyrimidine moiety: discovery of novel potential herbicidal agents

The synthesis of highly diverse libraries has become of paramount importance for obtaining novel leads for drug and agrochemical discovery. Herein, the step-economical diversity-oriented synthesis of a library of various pyrimidine-N-heterocycle hybrids was developed, in which a 4,6-dimethoxypyrimidine core was incorporated into nine kinds of N-heterocycles. A total of 34 structurally diverse compounds were synthesized via a two-step process from very simple and commercially available starting materials. Further, in vivo biological screening of this library identified 11 active compounds that exhibited good post-emergence herbicidal activity against D. sanguinalis at 750 g ai per ha. More importantly, pyrimidine-tetrahydrocarbazole hybrid 5q showed good to excellent herbicidal activity against five test weeds at the same dosage. Pyrimidine-tetrahydrocarbazole hybrids represent a novel class of herbicidal agents that may become promising lead compounds in the herbicidal discovery process.

Laboratory bioassay, greenhouse experiment and 3D-QSAR studies on berberine analogues: a search for new herbicides based on natural products

BACKGROUND

Berberine is a herbicidal chemical that we isolated from Coptis chinensis. In continuation of our program aimed at discovering and developing natural botanical herbicides, we evaluated the herbicidal activities of 39 berberine analogues and developed a three-dimensional quantitative structure-activity relationship (3D-QSAR) model.

RESULTS

Among these 39 analogs, the most active compounds were determined to be worenine chloride and coptisine chloride, with median inhibitory concentration (IC₅₀ ) values on all eight tested weed species of < 10 mg L^-1 . As a reference, the IC₅₀ values of berberine on six weed species were < 10 mg L^-1 . Furthermore, the results of a greenhouse experiment showed that at 10 mg L^-1 , and 7 days after treatment, the effects of worenine chloride and coptisine chloride on Lemna minor and Ageratum conyzoides were significantly higher than those of glyphosate and sulcotrione. In the 3D-QSAR analysis, the electrostatic field contour map indicated that introducing an electropositive group in the N-7, C-9 and C-10 positions would potentially improve the inhibition rate. A positively charged nitrogen atom at the N-7 position was important for activity. Replacement of -OCH₃ by -OH at the C-9 and C-10 positions could decrease the inhibitory activity, while the hydrophobic field contour map revealed that the hydrophobicity of the C-10 position was associated with high activity. Moreover, the hydrogen bond acceptor field contour map suggested that the existence of a hydrogen bond acceptor at the C-3 and C-9 positions might affect the inhibition rate.

CONCLUSIONS

3D-QSAR provided meaningful clues to the structural features of berberine analogues that will assist the design of more potent herbicidal compounds in the future. © 2020 Society of Chemical Industry.

Structural modification of 4, 5-dihydro-[1, 2, 4] triazolo [4, 3-f] pteridine derivatives as BRD4 inhibitors using 2D/3D-QSAR and molecular docking analysis

Cancer treatment continues to be one of the most serious public health issues in the world. The overexpression of BRD4 protein has led to a series of malignant tumors, hence the development of small molecule BRD4 protease inhibitors has always been a hot spot in the field of medical research. In this study, a series of 4,5-dihydro-[1, 2, 4] triazolo [4, 3-f] pteridine derivatives were used to establish 3D/2D-QSAR models and to discuss the relationship between inhibitor structure and activity. Four ideal models were established, including the comparative molecular field analysis (CoMFA: [Formula: see text] = 0.574, [Formula: see text] = 0.947) model, comparative molecular similarity index analysis (CoMSIA: [Formula: see text]= 0.622, [Formula: see text] = 0.916) model, topomer CoMFA ([Formula: see text] = 0.691, [Formula: see text]= 0.912) model and hologram quantitative structure-activity relationship (HQSAR: [Formula: see text]= 0.759, [Formula: see text] = 0.963) model. They show quite good external predictive power for the test set, with [Formula: see text] values of 0.602, 0.624, 0.671 and 0.750, respectively. In addition, the contour and color code map given by the 2D/3D-QSAR model with the results of molecular docking analyzed to chalk up modification methods for improving inhibitory activity, which was verified by designing novel compounds. The analysis results are helpful to promote the modification of the inhibitor framework and to provide a reference for the construction of new and promising BRD4 inhibitor compounds.

A computational approach for designing novel SARS-CoV-2 Mpro inhibitors: combined QSAR, molecular docking, and molecular dynamics simulation techniques

The promising compound T₂₁ for treating COVID-19 at the active site of SARS-CoV-2 M^pro.

The combination of HPLC and biological analysis to determine the quality markers and its structural composition of Eclipta prostrata L

INTRODUCTION

The diversity and complexity of components are important reasons for the unstable efficacy and safety of Chinese materia medica (CMM) in quality control. The good and stable quality control may be related to the quality markers with structural composition of multi-components.

OBJECTIVE

In the present study, we take Eclipta prostrata L. as a representative example. The 11 samples were collected from the different areas in China, and the discrepancy in bioactivity and chemical composition of these samples were compared. DOX (doxorubicin hydrochloride)-induced ICR mice were established for in vivo nephrotic syndrome experiments. The biochemical indicators including 24-h urine protein, triglyceride (TG), etc. were measured and the pathological change of kidney tissue was observed. MPC-5 cells damage model was induced to compare the difference of these samples in bio-activity. High-performance liquid chromatography (HPLC) method for 11 EEP (extract of Eclipta prostrata L.) samples were performed to analyse the content of the quality markers.

RESULTS

In vivo experiments, EEP could mitigate the content or activity of urine protein, TG, etc. compared with the positive group (TG content was 2.53 ± 0.39 mmol/L, urinary protein quantification on 35th day was 16.79 ± 2.32 mg). In vitro experiments, CCE (coumestans component of Ecliptae) and EEP had equivalent effects on biochemical indicators such as cell viability, etc. According to the HPLC analysis, the content of wedelolactone was 45.88% and demethylwedelolactone was 23.74% in CCE.

CONCLUSION

The CCE with a ratio of 2:1 can be considered as a quality marker of Eclipta prostrata L.. This research may provide a perspective for quality control of CMM.

Synthesis, Insecticidal Activities, and Structure-Activity Relationship of Phenylpyrazole Derivatives Containing a Fluoro-Substituted Benzene Moiety

Fluorinated organic compounds represent a growing and important family of commercial chemicals. Introduction of fluorine into active ingredients has become an effective way to develop modern crop protection products. Given the particular properties of fluorine and high efficiency and selectivity of diamide insecticides, we designed and synthesized 27 anthranilic diamides analogues containing fluoro-sustituted phenylpyrazole. A preliminary bioassay indicated that most target compounds exhibited good biological activity against Mythimna separata and Plutella xylostella. Compound IIIf containing a 2,4,6-trifluoro-substituted benzene ring showed 43% insecticidal activity against M. separata at 0.1 mg L^-1, while the control chlorantraniliprole was 36%. The activity of IIIe against P. xylostella at 10^-5 mg L^-1 was 94%, compared with that of the control being 70%. Thus, introduction of fluorine into diamide insecticides was useful for increasing activity. Insect electrophysiology studies showed that the calcium concentration in the nerve cells of third M. separata larvae was elevated by IIIf, which further confirmed that ryanodine receptor (RyR) was its potential target.

A Novel Series of [1,2,4]Triazolo[4,3-a]Pyridine Sulfonamides as Potential Antimalarial Agents: In Silico Studies, Synthesis and In Vitro Evaluation

For the development of new and potent antimalarial drugs, we designed the virtual library with three points of randomization of novel [1,2,4]triazolo[4,3-a]pyridines bearing a sulfonamide fragment. The library of 1561 compounds has been investigated by both virtual screening and molecular docking methods using falcipain-2 as a target enzyme. 25 chosen hits were synthesized and evaluated for their antimalarial activity in vitro against Plasmodium falciparum. 3-Ethyl-N-(3-fluorobenzyl)-N-(4-methoxyphenyl)-[1,2,4]triazolo[4,3-a]pyridine-6-sulfonamide and 2-(3-chlorobenzyl)-8-(piperidin-1-ylsulfonyl)-[1,2,4]triazolo[4,3-a]pyridin-3(2H)-one showed in vitro good antimalarial activity with inhibitory concentration IC₅₀ = 2.24 and 4.98 μM, respectively. This new series of compounds may serve as a starting point for future antimalarial drug discovery programs.

Monoterpenes and Their Derivatives-Recent Development in Biological and Medical Applications

Monoterpenes, comprising hydrocarbons, are the largest class of plant secondary metabolites and are commonly found in essential oils. Monoterpenes and their derivatives are key ingredients in the design and production of new biologically active compounds. This review focuses on selected aliphatic, monocyclic, and bicyclic monoterpenes like geraniol, thymol, myrtenal, pinene, camphor, borneol, and their modified structures. The compounds in question play a pivotal role in biological and medical applications. The review also discusses anti-inflammatory, antimicrobial, anticonvulsant, analgesic, antiviral, anticancer, antituberculosis, and antioxidant biological activities exhibited by monoterpenes and their derivatives. Particular attention is paid to the link between biological activity and the effect of structural modification of monoterpenes and monoterpenoids, as well as the introduction of various functionalized moieties into the molecules in question.

Synthesis and Pesticidal Activities of New Quinoxalines

Natural products are a source of many novel compounds with biological activity for the discovery of new pesticides and pharmaceuticals. Quinoxaline is a fused N-heterocycle in many natural products and synthetic compounds, and seven novel quinoxaline derivatives were designed and synthesized via three steps. Pesticidal activities of title quinoxaline derivatives were bioassayed. Most of these compounds had herbicidal, fungicidal, and insecticidal activities. The compounds 2-(6-methoxy-2-oxo-3-phenylquinoxalin-1(2H)-yl)acetonitrile (3f) and 1-allyl-6-methoxy-3-phenylquinoxalin-2(1H)-one (3g) were the most active herbicides and fungicides. Mode-of-action studies indicated that 3f is a protoprophyrinogen oxidase-inhibiting herbicide. Compound 3f also possessed broad-spectrum fungicidal activity against the plant pathogen Colletotrichum species. Some of these compounds also had insecticidal activity. Molecular docking and DFT analysis can potentially be used to design more active compounds.

Synthesis and herbicidal activity of novel pyrazole aromatic ketone analogs as HPPD inhibitor

BACKGROUND

4-Hydroxyphenylpyruvate dioxygenase (HPPD, EC 1.13.11.27) has been a good target for herbicide discovery. In order to discover novel HPPD herbicides, a series of pyrazole aromatic ketone analogs were designed and synthesized.

RESULTS

The 25 pyrazole aromatic ketone analogs synthesized were tested for herbicidal activity and compounds A1, A3, A4, A17, A20 and A25 displayed excellent herbicidal activity against Chenopodium serotinum, Stellaria media and Brassica juncea at 37.5 g ha^-1 . In addition, compounds A1, A5, A9, A10, A16, A17, A20 and A25 exhibited good crop selectivity for wheat, maize and rice at 150 g ha^-1 . Inhibition activities against AtHPPD proved the compounds were HPPD inhibitors. The structure-activity relationship of these pyrazole aromatic ketone analogs was studied using molecular docking.

CONCLUSION

These pyrazole aromatic ketone derivatives could be used as lead structures for development of HPPD herbicides against dicotyledonous weeds with further structure modification. © 2019 Society of Chemical Industry.

One-pot synthesis, structure and structure-activity relationship of novel bioactive diphenyl/diethyl (3-bromo-1-(3-chloropyridin-2-yl)-1H-pyrazol-5-yl)(arylamino)methylphosphonates

BACKGROUND

N-Pyridylpyrazole derivatives have received continuous attention in agrochemical research during the last decade owing to their remarkable insecticidal or fungicidal potentials. To look for novel heterocyclic agrochemicals for increasing production of agriculture, a series of novel α-aminophosphonate derivatives containing N-pyridylpyrazole moiety were synthesized.

RESULTS

The structures of the title compounds were confirmed via melting point, IR, ¹ H NMR, ¹³ C NMR, ³¹ P NMR, HRMS and elemental analysis. The single crystal structure of diethyl (3-bromo-1-(3-chloropyridin-2-yl)-1H-pyrazol-5-yl)(2,6-dimethylphenylamino)methylphosphonate (compound 12b) was first reported. Moreover, the bioassays displayed that the title compounds exhibited modest or weak insecticidal activities against oriental armyworm at 200 μg mL^-1 . The first investigation on the fungicidal potential of chlorantraniliprole showed no significant activities towards the six tested fungi found in this study, however, most of the title compounds displayed apparent in vitro fungicidal activity against some plant fungi, in particular excellent activities towards Physalospora piricola. Compounds 11a and 11b had EC₅₀ values of 18.8 and 17.4 μg mL^-1 , respectively, which were comparable with that of fungicide control triadimefon (EC₅₀  = 24.7 μg mL^-1 ) against Physalospora piricola. In addition, some compounds exhibited modest in vivo control efficacy at 0.5 mg mL^-1 towards Sclerotinia sclerotiorum (11b: 30.1(±1.8)%), Rhizoctonia cerealis (11a: 20.4(±2.1)%; 11b: 30.2(±2.2)%), and Erysiphe graminis (11a: 30.3(±1.8)%; 12d: 40.2(±0.9)%).

CONCLUSION

Compounds 11a, 11b and 12d could be promising new lead structures for the development and discovery of novel fungicides towards Physalospora piricola and Erysiphe graminis. The structure-activity relationship (SAR) analysis provided useful guidance and new understanding for the design of novel pyridylpyrazole-containing agrochemicals. © 2019 Society of Chemical Industry.

Novel 4-pyrazole carboxamide derivatives containing flexible chain motif: design, synthesis and antifungal activity

BACKGROUND

In recent years, carboxamide fungicides, targeting succinate dehydrogenase (SDH), have shown highly efficient and broad spectrum fungicidal activity. Structure-activity relationship (SAR) results for these commercial fungicides show that the carboxamide group was a key active group. This is useful information for the discovery of new pyrazole carboxamide derivatives with fungicidal activity.

RESULTS

Twenty-seven novel pyrazole carboxamides were designed and synthesized. Their fungicidal activities against Gibberella zeae, Phytophthora infestans, Phytophthora capsici, Rhizoctonia solani, Alternaria solani, Botrytis cinerea, Fusarium oxysporum, Cercospora arachidicola, Sclerotinia sclerotiorum and Physalospora piricola were tested; derivatives possessed excellent inhibitory at 50 mg L^-1 in particular. Furthermore, some pyrazole carboxamides exhibited remarkably high activities against Sclerotinia sclerotiorum in vitro with EC₅₀ values of 2.04 to 15.2 μg mL^-1 . In addition, some compounds also exhibited high activities against Physalospora piricola, Cercospora arachidicola and Phytophthora capsici. Inhibition activities against SDH proved that the designed analogues were effective at the enzyme level. The SAR of these pyrazole carboxamides was studied by using the docking method.

CONCLUSION

It is possible that pyrazole carboxamides, which exhibit good activity against Sclerotinia sclerotiorum, can be further optimized as a lead compounds of carboxamide fungicides. © 2019 Society of Chemical Industry.

Synthesis, Crystal Structure, and Agricultural Antimicrobial Evaluation of Novel Quinazoline Thioether Derivatives Incorporating the 1,2,4-Triazolo[4,3-a]pyridine Moiety

A total of 22 quinazoline thioether derivatives incorporating a 1,2,4-triazolo[4,3-a]pyridine moiety were designed, synthesized, and evaluated as antimicrobial agents in agriculture. Among these compounds, the chemical structure of compound 6l was further confirmed via single-crystal X-ray diffraction analysis. The bioassay results revealed that some of the compounds possessed noticeable in vitro antibacterial activities against the tested phytopathogenic bacteria. For example, compounds 6b and 6g had EC₅₀ values as low as 10.0 and 24.7 μg/mL against Xanthomonas axonopodis pv. citri (Xac), respectively, which were significantly better than that of the commercial agrobactericide bismerthiazol (56.9 μg/mL). Particularly, compound 6b was also found to be capable of suppressing the pathogenic bacterium Xanthomonas oryzae pv. oryzae (Xoo) approximately 12-fold more potent than control bismerthiazol, in terms of their EC₅₀ values (7.2 versus 89.8 μg/mL). Importantly, the most active compound 6b turned out to be one with the highest hydrophilicity and the lowest molecular weight within the series. In vivo bioassays further showed the application prospect of 6b as a promising plant bactericide for controlling Xoo. Additionally, in vitro antifungal activities of these compounds were also evaluated at the concentration of 50 μg/mL. Overall, the present study demonstrated the potential of 1,2,4-triazolo[4,3-a]pyridine-bearing quinazoline thioether derivatives as efficient agricultural antibacterial agents for crop protection.

Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

A series of novel 3-methylphosphonylated [1,2,4]triazolo[4,3-a]pyridines was accessed through a 5-exo-dig-type cyclization of chloroethynylphosphonates and commercially available N-unsubstituted 2-hydrazinylpyridines. In addition, 3-methylphosphonylated [1,2,4]triazolo[4,3-a]quinolines and 1-methylphosphonylated [1,2,4]triazolo[3,4-a]isoquinolines were synthesized in a similar manner. The presence of a NO₂ group in the starting hydrazinylpyridine induces a Dimroth-type rearrangement leading to 2-methylphosphonylated [1,2,4]triazolo[1,5-a]pyridines.

Novel [1,2,3]triazolo[1,5-a]pyridine derivatives are trypanocidal by sterol biosynthesis pathway alteration

Aim: To study a new series of [1,2,3]triazolo[1,5-α]pyridine derivatives as trypanocidal agents because current antichagasic pharmacologic therapy is only partially effective. Materials & methods: The effect of the series upon Trypanosoma cruzi epimastigotes and murine macrophages viability, cell cycle, cell death and on the metabolites of the sterol biosynthesis pathway was measured; also, docking in 14α-demethylase was analyzed. Results: Compound 16 inhibits 14α-demethylase producing an imbalance in the cholesterol/ergosterol synthesis pathway, as suggested by a metabolic control and theoretical docking analysis. Consequently, it prevented cell proliferation, stopping the cellular cycle at the G2/M phase, inducing cell death. Conclusion: Although the exact cell death mechanism remained elusive, this series can be used for the further rational design of novel antiparasitic molecules.

Novel Trifluoromethylpyrazole Acyl Thiourea Derivatives: Synthesis, Antifungal Activity and Docking Study

Background:

In recent years, pyrazole carboxamide derivatives possessed excellent fungicidal activity. In the process of designing new fungicides, the carboxamide group was modified in order to find novel structure pyrazole carboxamide derivatives.

Methods:

Ten novel trifluoromethyl pyrazole acyl thiourea derivatives were designed and synthesized. In vivo fungicidal activities of these compounds were tested against Fusarium oxysporum, Corynespora mazei and Botrytis cinerea, respectively

Results:

Particularly compounds exhibited significant control effective at 100 mg/L. More importantly, some compounds showed the good control effective at 10 mg/L. Furthermore, docking was established to study the structure-activity relationship of the title compounds.

Conclusion:

It is possible that trifluoromethylpyrazole acyl thiurea derivatives, which possess good control effective against Botrytis cinerea, may become novel lead compounds for the development of fungicides with further structure modification.

Crystal structure and molecular docking studies of new pyrazole-4-carboxamides

Two pyrazol-4-carboxamides, 3-(difluoromethyl)-N-(mesitylcarbamoyl)-1-methyl-1H-pyrazole-4-carboxa-mide (7a) and 3-(difluoromethyl)-N-((3,5-dimethylphenyl) carbamoyl)-1-methyl-1H-pyrazole-4-carboxamide (7b) were synthesized and their structures were confirmed by the aid of 1H NMR and HRMS analyses. The structure of the pyrazole-4-carboxamide, 7a was also determined by X-ray diffraction. The preliminary activity results demonstrate that these two compounds exhibit good inhibitory activity against Botrytis cinerea. Further docking results indicated that the key active group is difluoromethyl pyrazole moiety.

Toxicity of a molluscicide candidate PPU07 against Oncomelania hupensis (Gredler, 1881) and local fish in field evaluation

Schistosomiasis japonica caused by Schistosoma japonicum infection is recognized as a considerable economic and public health concern in Asia. Oncomelania hupensis is the sole intermediate host of S. japonicum. The only molluscicide recommended by World Health Organization (WHO) since 1960s is relative toxic to other aquatic species. In this article, we evaluated the novel molluscicide PPU07 in field trials on their efficiency against O. hupensis and toxicity for local fish. 25% PPU07 sulfate WP exhibited similar molluscicidal effect at 2.0 g/m² and 2.0 g/m³ in the spraying and immersion trials with the WHO recommended molluscicide niclosamide (1 g/m² and 1 g/m³). The mortality rates reached 95% and 96%, respectively. Moreover, little toxicity was observed for local fish and other aquatic organisms at the effective molluscicidal concentrations. In all, 25% PPU07 sulfate WP is a promising molluscicide for snail control, particularly in semi-commercial or commercial aquaculture ponds.

Design, Synthesis and Insecticide Activity of Novel Acetylcholinesterase Inhibitors: Triazolinone and Phthalimide Heterodimers

Based on the "cluster effect" and the structure characters of acetylcholinesterase (AChE; EC 3.1.1.7), a new series of 1,2,4-triazolin-3-one and phthalimide heterodimers were designed, synthesized, and evaluated as potent dual acetylcholinesterase inhibitors (AChEIs). Most of the synthesized compounds showed good in vitro inhibitory activities towards both Drosophila melanogaster acetylcholinesterase (DmAChE) and Musca domestica acetylcholinesterase (MdAChE). Among them, 5g was found to be the most potent anti-AChE derivate (5g, IC₅₀ = 8.07 µM to DmAChE, IC₅₀ = 32.24 µM to MdAChE). It was 2.31- and 1.35-fold more active than the positive control ethion (CP, IC₅₀ = 18.62 µM to DmAChE, IC₅₀ = 43.56 µM to MdAChE). The docking model study revealed that 5g possessed the fitted spatial structure and bound to the central pocket and peripheral site of DmAChE. Moreover, most compounds demonstrated high insecticidal activity to Lipaphis erysimi and Tetranychus cinnabarinus at the concentration of 300 mg/L.

Synthesis, Nematicidal Activity and Docking Study of Novel Pyrazole-4-Carboxamide Derivatives Against Meloidogyne incognita

Background:

A series of novel 2,6-dichloro-4-(trifluoromethyl)phenyl)-3-(difluoromethyl)- 1H-pyrazole-4-carboxamide derivatives were designed and synthesized.

Methods:

All the title compounds were confirmed by 1H NMR and MS.

Results and Conclusion:

The primarily nematicidal activity results indicated that some of them exhibited moderate control efficacy against the tomato root-knot nematode disease caused by Meloidogyne incognita.

Synthesis, Molecular Docking and in Vitro Screening of Some Newly Synthesized Triazolopyridine, Pyridotriazine and Pyridine⁻Pyrazole Hybrid Derivatives

A series of novel pyridine and fused pyridine derivatives have been prepared starting from 6-(3,4-dimethylphenyl)-2-hydrazinyl-4-(thiophen-2-yl)-pyridine-3-carbonitrile 1 which on treatment with appropriate formic acid, acetic acid/acetic anhydride, benzoyl chloride and/or carbon disulfide afforded the corresponding triazolopyridine derivatives 2–5. Also, treatment of hydrazide 1 with diethyloxalate, chloroacetyl chloride, chloroacetic acid and/or 1,2-dichloroethane yielded the corresponding pyridotriazine derivatives 7–10. Further transformation of compound 1 with a different active methylene group, namely acetyl acetone, diethylmalonate, ethyl cyanoacetate, ethyl benzoylacetate and/or ethyl acetoacetate, produced the pyridine–pyrazole hybrid derivatives 11–15. These newly synthesized compounds (1–15) were subjected to in silico molecular docking screenings towards GlcN-6-P synthase as the target protein. The results revealed moderate to good binding energies of the ligands on the target protein. All the newly prepared products exhibited antimicrobial and antioxidant activity.

KI-catalyzed oxidative cyclization of α-keto acids and 2-hydrazinopyridines: efficient one-pot synthesis of 1,2,4-triazolo[4,3-a]pyridines

A one-pot approach to 1,2,4-triazolo[4,3-a]pyridines via KI-catalyzed oxidative cyclization was developed with good economical and environmental advantages.

Synthesis, insecticidal activity and inhibition on topoisomerase I of 20(S)-t-Boc-amino acid derivatives of camptothecin

Camptothecin (CPT), a quinolone alkaloid extracted from Camptotheca acuminata Decne, exhibits potential insecticidal activities against various insect species. Our previous studies have showed that CPT induced apoptosis in Spodoptera exigua Hübner cell line and inhibited the relaxation activity of topoisomerase I (Topo I). In this study, total seven 20(S)-t-butoxy carbonyl-amino acid derivatives of CPT were synthesized and evaluated for insecticidal activities, cytotoxicity and Topo I inhibitory activities. Results showed that introduction of t-Boc amino acids to 20-position on CPT improves contact assay and cytotoxicity of most derivatives toward S. exigua but reduces inhibitory effect on relaxation activity of S. exigua Topo I. Furthermore, compounds 1d and 1g demonstrated higher level of contact activities and cytotoxicity than CPT and hydroxyl-camptothecin (HCPT), which are potential to be developed as potential insecticides targeted at more than Topo I.