3D-QSAR Directed Discovery of Novel Halogenated Phenyl 3-Trifluoroethoxypyrazole Containing Ultrahigh Active Insecticidal Anthranilic Diamides

The Hoverfly Attracting Property of a Methyl Salicylate-Containing (E)-β-Farnesene Analog (3e) and Potential Mechanism by Mediating the EcorOBP15 and EcorOR3

Using natural enemies provides a sustainable method to control major agricultural pests. Hoverflies are significant natural enemies of aphids and efficient pollinators. Herbivore-induced plant volatiles (HIPVs), including (E)-β-farnesene (EBF) and methyl salicylate (MeSA), are key olfactory cues mediating hoverflies behavior. Our previous work identified compound 3e, an EBF analog containing a MeSA moiety, exhibited aphid-repelling and ladybug-attracting activities. However, whether 3e can attract hoverflies remains unknown. Therefore, this study explored the attractant property and potential mechanism of 3e toward hoverflies. Laboratory bioassays and field trials indicated 3e has an obvious hoverfly attracting property. The attraction mechanism studies demonstrate that, similar to EBF, 3e can interact with EcorOBP15 and EcorOR3, with its greater chemical softness, larger hydrophobic and charge regions enhancing these interactions. Furthermore, 3e exhibited low toxicity to honeybees (Apis mellifera) and hoverflies (Eupeodes corollae). Consequently, 3e could be a promising eco-friendly behavioral regulator for integrated aphid management in sustainable agriculture.

Computer-aided design of novel anthranilic diamides containing fluorinated alkoxy groups as potential ryanodine receptor insecticides

BACKGROUND

Increasing the diversity of lead compounds has been shown to enhance the efficacy of diamide insecticides. Fifty novel compounds were precisely designed and synthesized utilizing fragment-based assembly and virtual screening coupling.

RESULTS

The median lethal concentration (LC50) values of compounds X-30 and X-40 against Mythimna separata were 0.09 and 0.08 mg L-1, respectively, which are lower than that of chlorantraniliprole (CHL, 0.11 mg L-1). Notably, compounds X-10, X-18, X-25, X-32 and X-43 had corresponding LC50 values of 2.0 × 10-4, 5.0 × 10-4, 6.0 × 10-4, 9.0 × 10-4 and 7.0 × 10-4 mg L-1 against Plutella xylostella, respectively. The best compound X-10 exhibited five-fold greater efficacy than CHL (1.0 × 10-3 mg L-1). The LC50 values of compounds X-21, X-29, and X-40 against Spodoptera frugiperda were 0.27, 0.26 and 0.25 mg L-1, respectively, which are slightly lower than that of CHL (0.33 mg L-1). In the case of Ostrinia furnacalis, compound X-43 showed good efficacy with LC50 values comparable to those of CHL (1.38 versus 1.57 mg L-1). Calcium imaging experiments demonstrated that X-21 acted on S. frugiperda ryanodine receptors. Furthermore, this series of compounds showed safety toward nontarget mammals compared to CHL.

CONCLUSION

The introduction of fluorinated alkoxy groups at the 3-position of the pyrazole ring leads to good insecticidal activity and improved insect selectivity. © 2025 Society of Chemical Industry.

Discovery of Enantiopure (S)-Methoprene Derivatives as Potent Biochemical Pesticide Candidates

(S)-Methoprene has been widely applied as a powerful biochemical pesticide to control disease vectors and other pestiferous arthropods of economic importance. As a juvenile hormone analogue, many products based on (S)-methoprene are developed and commercialized in the USA, Europe, and elsewhere. However, the agricultural use of (S)-methoprene and its analogues remains underexplored. Here, based on an intermediate derivatization strategy and structural modification, a series of enantiopure (S)-methoprene derivatives were designed for their expected bioactivity against two crop-threatening pests. Six compounds showed more than 2-fold stronger inhibition of emergence against Plutella xylostella than (S)-methoprene, among which one that was designated as B2 showed even superior activity to the conventional chemical pesticide and biopesticide with IE50 of 0.02 mg/L. Nine compounds exhibited over 2-fold higher bioactivity against Aphis craccivora growth than (S)-methoprene. The physicochemical property evaluation and toxicological test showed that the potent (S)-methoprene derivatives were low toxic to the nontarget organism and the environment. Molecular docking studies further demonstrated that the high bioactivity of B2 may be partially attributed to its great affinity for binding to juvenile hormone receptors of P. xylostella. The current study suggests that B2 is a biochemical pesticide candidate with potency to be developed as a new agrochemical for lepidopteran control.

Discovery of Trisubstituted N-Phenylpyrazole Containing Diamides with Improved Insecticidal Activity

To increase the structural diversity of insecticides and meet the needs of effective integrated insect management, the structure of chlorantraniliprole was modified based on a previously established three-dimensional quantitative structure-activity relationship (3D-QSAR) model. The pyridinyl moiety in the structure of chlorantraniliprole was replaced with a 4-fluorophenyl group. Further modifications of this 4-fluorophenyl group by introducing a halogen atom at position 2 and an electron-withdrawing group (e.g., iodine, cyano, and trifluoromethyl) at position 5 led to 34 compounds with good insecticidal efficacy against Mythimna separata, Plutella xylostella, and Spodoptera frugiperda. Among them, compound IV f against M. separata showed potency comparable to that of chlorantraniliprole. IV p against P. xylostella displayed a 4.5 times higher potency than chlorantraniliprole. In addition, IV d and chlorantraniliprole exhibited comparable potencies against S. frugiperda. Transcriptome analysis showed that the molecular target of compound IV f is the ryanodine receptor. Molecular docking was further performed to verify the mode of action and insecticidal activity against resistant P. xylostella.

Novel Evodiamine-Based Sulfonamide Derivatives as Potent Insecticide Candidates Targeting Insect Ryanodine Receptors

Pests represent an important impediment to efficient agricultural production and pose a threat to global food security. On the basis of our prior research focused on identifying insecticidal leads targeting insect ryanodine receptors (RyRs), we aimed to identify evodiamine scaffold-based novel insecticides. Thus, a variety of evodiamine-based derivatives were designed, synthesized, and assessed for their insecticidal activity against the larvae of Mythimna separata (M. separata) and Plutella xylostella (P. xylostella). The preliminary bioassay results revealed that more than half of the target compounds exhibited superior activity compared to evodiamine, matrine, and rotenone against M. separata. Among these, compound 21m displayed the most potent larvicidal efficiency, with a remarkable mortality rate of 93.3% at 2.5 mg/L, a substantial improvement over evodiamine (10.0% at 10 mg/L), matrine (10.0% at 200 mg/L), and rotenone (30.0% at 200 mg/L). In the case of P. xylostella, compounds 21m and 21o displayed heightened larvicidal activity, boasting LC50 values of 9.37 × 10-2 and 0.13 mg/L, respectively, surpassing that of evodiamine (13.41 mg/L), matrine (291.78 mg/L), and rotenone (18.39 mg/L). A structure-activity relationship analysis unveiled that evodiamine-based derivatives featuring a cyclopropyl sulfonyl group at the nitrogen atom of the B ring and a fluorine atom in the E ring exhibited more potent larvicidal effects. This finding was substantiated by calcium imaging experiments and molecular docking, which suggested that 21m could target insect RyRs, including resistant mutant RyRs of P. xylostella (G4946E and I4790M), with higher affinity than chlorantraniliprole (CHL). Additionally, cytotoxicity assays highlighted that the potent compounds 21i, 21m, and 21o displayed favorable selectivity and low toxicity toward nontarget organisms. Consequently, compound 21m emerges as a promising candidate for further development as an insecticide targeting insect RyRs.

Discovery of novel thiazolyl anthranilic diamide derivatives as insecticidal candidates

BACKGROUND

Agricultural pests have caused huge losses in agricultural production and threaten global food security. Synthetic insecticides remain the major control method. However, with the rapid development of pest resistance and the increasingly stringent regulations on pesticide usage, the development of efficient insecticides with novel structures is particularly urgent.

RESULTS

Twenty-six novel anthranilic diamide derivatives containing the thiazole moiety were designed based on the scaffold hopping strategy. Bioassay results indicated that compound 6e exhibited excellent insecticidal activity against a susceptible strain of diamondback moth (Plutella xylostella) with a median lethal concentration (LC50 ) of 0.65 mg L-1 , which was similar to chlorantraniliprole (LC50  = 0.53 mg L-1 ). Compound 6e showed marginally lower (LC50  = 50.45 mg L-1 ) insecticidal activity than chlorantraniliprole (LC50  = 31.98 mg L-1 ) on chlorantraniliprole-resistant P. xylostella larvae, suggesting a cross-resistance of compound 6e with chlorantraniliprole (resistance ratios, 77.6-fold and 60.3-fold, respectively). Compound 6e also showed good insecticidal activity against fall armyworm and beet armyworm with pest mortalities of 74% and 64%, respectively, at 5 mg L-1 concentration. In addition, compounds 6e and 12a showed delayed toxicity against red imported fire ant with mortality rates of 84% and 85% (respectively) after 5 days of treatment at 1.0 mg L-1 , which were superior to that of chlorantraniliprole.

CONCLUSION

The introduction of thiazole into anthranilic diamide scaffolds resulted in insecticidal leads 6e and 12a with excellent insecticidal activities and potential application in controlling red imported fire ants. The work also guides the discovery of insecticidal molecules with thiazole-containing anthranilic diamide scaffold. © 2023 Society of Chemical Industry.

3D-QSAR Combination with Molecular Dynamics Simulations to Effectively Design the Active Ryanodine Receptor Agonists against Spodoptera frugiperda

Computer-aided molecular modeling was applied to design a series of Spodoptera frugiperda RyR agonists. Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were used to generate 3D-QSAR models. MD simulations in the complex with S. frugiperda native, mutant RyR, and mammalian RyR1 under physiological conditions were used to validate the detailed binding mechanism. Binding free energy calculation by molecular mechanics generalized surface area (MM-GBSA) explained the role of key amino acid residues in ligand-receptor binding. Therefore, 14 new compounds were effectively designed and synthesized, and a bioassay indicated that compounds A-2 and A-3 showed comparable activity to that of chloranthraniliprole with LC50 values of 0.27, 0.18, and 0.20 mg L-1, respectively, against S. frugiperda. Most target compounds also displayed good activity against Mythinma separata at 0.1 mg L-1. Molecular docking and MM-GBSA calculations demonstrated that A-3 had a better binding capacity with native and mutant S. frugiperda RyRs.

CoMFA Directed Molecular Design for Significantly Improving Fungicidal Activity of Novel [1,2,4]-Triazolo-[3,4-b][1,3,4]-thiadizoles

Target based molecular design via the aid of computation is one of the most efficient methods in the discovery of novel pesticides. Here, a combination of the comparative molecular field analysis (CoMFA) and molecular docking was applied for discovery of potent fungicidal [1,2,4]-triazolo-[3,4-b][1,3,4]-thiadiazoles. Bioassay results indicated that the synthesized target compounds 3a, 3b, and 3c exhibited good activity against Alternaria solani, Botrytis cinerea, Cercospora arachidicola, Fusarium graminearum, Physalospora piricola, Rhizoctonia solani, and Sclerotinia sclerotiorum with an EC50 value falling between 0.64 and 16.10 μg/mL. Specially, 3c displayed excellent fungicidal activity against C. arachidicola and R. solani, which was 5 times more potent than the lead YZK-C22. The enzymatic inhibition assay and fluorescence quenching analysis with R. solani pyruvate kinase (RsPK) showed a weaker binding affinity between RsPK and 3a, 3b, or 3c. Transcriptomic analyses showed that 3c exerted its fungicidal activity by disrupting steroid biosynthesis and ribosome biogenesis in eukaryotes. These findings support that 3c is a promising fungicide candidate, and a fine modification from a lead may lead to a totally different mode of action.

Discovery of Novel Diamides Scaffold Containing Monofluoro-acrylamides Activating the Insect Ryanodine Receptor

The research and development of organofluorine chemistry has flourished; in particular, monofluoroalkene has aroused considerable interest from medicinal and organic chemists. It is a significant attempt to introduce monofluoroalkene into agrochemicals. In this study, monofluoroalkene was introduced into diamide molecules and inserted between the aliphatic amide and benzene ring, and 44 compounds have been successfully synthesized. The bioassay results showed that compounds with monofluoro-acrylamide moiety (Z-isomers) had excellent larvicidal activity against lepidopteran pests at 5 mg·L-1. The LC50 values of compounds B16, B18, and B21 against Mythimna separata were 1.02, 1.32, and 0.78 mg·L-1, respectively. 3D-QSAR analysis including the CoMFA model and the CoMSIA model was conducted to illustrate the contributions of steric, electrostatic, hydrophobic, and hydrogen bond fields on the bioactivity. Moreover, typical symptoms caused by chlorantraniliprole including dehydration, shrinkage, and blackening were also observed on the test larvae treated with monofluoro-acrylamide diamide compounds. M. separata central neurons calcium imaging experiment of compound B18 indicated that the monofluoro-acrylamide diamide compounds were potential insect ryanodine receptor activators. The molecular docking was performed in the CHL binding domain of Plutella xylostella RyR and revealed that the predicted binding mode of compound B21 was slightly different from that of CHL. The MM|GBSA dG Bind values of B21 and CHL with P. xylostella RyR were respectively -85.797 and -95.641 kcal·mol-1. The present work explored the insecticidal properties of a new diamide scaffold containing a monofluoro-acrylamide fragment and extended the application of monofluoroalkene in the agrochemical field.

Design, Synthesis, and Insecticidal Evaluation of N-Pyridylpyrazole Amide Derivatives Containing 4,5-Dihydroisoxazole Amide as Potential Ryanodine Receptor Activators

Using the 4,5-dihydroisoxazol amide structure to expand the aliphatic amide moiety of chlorantraniliprole, a series of 28 novel N-pyridylpyrazolecarboxamide derivatives containing 4,5-dihydroisoxazol amide fragment were designed and synthesized. All target compounds had been properly characterized and confirmed by 1H NMR, 13C NMR, and HRMS, and the effects were evaluated against Mythimna separata (M. separata) and Plutella xylostella (P. xylostella). The bioassay results indicated that most of the target compounds exhibited good insecticidal activities against M. separata and P. xylostella at 50 mg/L; especially, compound A4 showed an LC50 value of 3.27 mg/L against M. separata. Calcium imaging experiments indicated that the target compound A4 had a similar mechanism of action to chlorantraniliprole, causing an increase in the cytoplasmic Ca2+ concentration. The molecular docking revealed the possible binding mode of compound A4 with a ryanodine receptor.