Aug 2026· Journal of Agricultural and Food Chemistry· Vol 74, pp. 26031-26042· 0 citations· 55 references
TL;DR
Findings suggested that compound 6m might be a potent candidate as a succinate dehydrogenase inhibitor (SDHI) against R. solani with strong protective and curative effects even at 50 μg/mL.
Abstract
In this study, 30 tetrahydroquinoline-based pyrazole-4-carboxamide derivatives were designed, synthesized, and screened for antifungal activities. Among them, compound 6m displayed the strongest inhibitory activity against Rhizoctonia solani, with a half-maximal effective concentration (EC50) as low as 0.03 μg/mL, superior to Boscalid (EC50 = 0.40 μg/mL) and Fluxapyroxad (EC50 = 0.06 μg/mL). Further detached-leaf assays on rice verified that 6m could markedly suppress the growth of R. solani with strong protective and curative effects even at 50 μg/mL. Follow-up mechanistic studies indicated that compound 6m might exert antifungal activity through SDH inhibition-related mechanisms. These findings suggested that compound 6m might be a potent candidate as a succinate dehydrogenase inhibitor (SDHI) against R. solani. Further research, including field trials and biosafety assessment, was needed to realize the potential of compound 6m as an effective tool for rice protection.
Twenty-three novel flavonol derivatives bearing a 1,2,3,4-tetrahydroquinoline (THQ) scaffold were designed and synthesized, and their antifungal activities against eight plant pathogenic fungi were evaluated. Several compounds exhibited 100% inhibition against Sclerotinia sclerotiorum and Phytophthora capsici (Pc). Among them, Q8 showed the most potent activity against Pc with an EC50 value of 4.1 μg mL–1, superior to azoxystrobin (69.0 μg mL–1) and fluopyram (123.2 μg mL–1). In vivo tests on chili fruits demonstrated that Q8 at 200 μg mL–1 provided superior curative and protective effects (73.7 and 80.8%) compared to azoxystrobin (53.0 and 54.4%). Mechanistic studies revealed that Q8 disrupted cell membrane integrity and inhibited succinate dehydrogenase (SDH) activity, with computational simulations suggesting a higher binding affinity for SDH than fluopyram. Safety evaluation showed no obvious adverse effects on seed germination or earthworm survival. Collectively, these results indicate that Q8 represents a promising lead compound for fungicide development.
Qingxue Hu, Xiaoting Geng, Fang Tian et al.· Journal of Agricultural and...· 0 citations
Transketolase (TKL, EC 2.2.1.1) was confirmed as a potential new target for herbicides. In this study, a series of pyrazole-fusaric acid derivatives 9a-9o were designed and synthesized via structural optimization of compound 7r. Among them, compound 9f exhibited good inhibition on Digitaria sanguinalis and Amaranthus retroflexus (inhibition >95%) even at 10 mg/L via the small cup method. It exhibited excellent inhibition against D. sanguinalis and A. retroflexus (inhibition >90%, 150 g ai/ha) via the pot bioassay superior to the positive control. Significantly, it showed good crop safety to maize, wheat, soybean, and cotton (the phytotoxicity <10%, 375 g ai/ha). Additionally, compound 9f exhibited excellent inhibition on both SvTKL and NtPPO (IC50: 0.11, 1.00 mg/L). Both molecular docking and molecular dynamics simulation confirmed that the complexes for SvTKL-9f and NtPPO-9f demonstrated strong stability. Altogether, there is potential to discover novel dual-target-inhibiting herbicide candidates by further structurally optimizing compound 9f.
Yongqi Liu, Chengkun Li, Xizheng Ma et al.· Journal of Agricultural and...· 0 citations
A series of 30 novel α-methylene-γ-butyrolactone (MBL) derivatives were designed and synthesized. Bioassays revealed that several compounds exhibited potent fungicidal activities against Valsa mali, Rhizoctonia solani, and Phytophthora capsici. A25 showed the highest activity against V. mali (EC50 = 0.70 mg/L). Against R. solani, A5 (EC50 = 0.94 mg/L) and A21 (EC50 = 0.69 mg/L) were highly active. Against P. capsici, A14 (EC50 = 0.69 mg/L), A21 (EC50 = 0.59 mg/L), and A24 (EC50 = 0.71 mg/L) displayed potent antioomycete activity. At 200 mg/L, A21 provided protective (88.9%) and curative (67.0%) effects in potted rice against R. solani as well as protective (91.0%) and curative (85.4%) effects on pepper plants against P. capsici. Mechanistic studies indicated that A21 blocks ATP synthesis and impairs energy metabolism. Toxicity assessment showed that A21 was nontoxic to earthworms and silkworms at the tested concentrations. This work provides insights for developing MBL derivatives as potential fungicides.
Deyou Yang, Heng Li, Jiaying Xu et al.· Journal of Agricultural and...· 0 citations
As part of an ongoing effort to develop novel succinate dehydrogenase inhibitors (SDHIs), a range of innovative nicotinamide derivatives featuring stilbene scaffolds were synthesized and assessed for their antifungal properties. Lead compounds 6g and 6c demonstrated significant antifungal efficacies against Rhizoctonia solani and Sclerotinia sclerotiorum, with EC50 (half maximal effective concentration) values of 0.008 and 0.034 μg/mL, respectively, surpassing Boscalid (EC50 = 0.573 and 0.455 μg/mL, respectively) and Fluxapyroxad (EC50 = 0.026 and 0.037 μg/mL, respectively). Detached leaf assays further confirmed their excellent protective and curative effects, outperforming Boscalid and Fluxapyroxad. Further studies revealed that compound 6g operated through a mechanism akin to Boscalid and Fluxapyroxad. These results indicated that both 6g and 6c showed great potential as novel SDHIs for effectively managing R. solani and S. sclerotiorum, underscoring the necessity for further research to fully explore their capabilities.
Bo Luo, Yihan Hu, Yi Zhao et al.· Journal of Agricultural and...· 0 citations
In this study, 22 novel formononetin derivatives bearing benzothiazole were designed and synthesized, and their antifungal activities against nine plant pathogens were evaluated. H2 exhibited promising activity against Phomopsis sp. (P. sp.) (EC50 = 9.85 μg/mL), superior to azoxystrobin (Az, EC50 = 41.1 μg/mL). At 200 μg/mL, H2 showed curative and protective efficacies of 58.4 and 64.5% against kiwifruit soft rot, outperforming Az (41.6 and 48.2%). Preliminary phenotypic investigations suggested that H2 might disrupt cell wall and membrane integrity, causing electrolyte leakage and malondialdehyde (MDA) accumulation, while mitochondrial membrane potential dissipation further hinted at impaired mitochondrial function. Although the precise molecular target remains unknown, H2 shows promise as a lead candidate, and the benzothiazole moiety appears critical for enhancing activity. This study provides a preliminary basis for developing eco-friendly fungicides.
Dan Shen, Xiaoyan Pan, Han Yang et al.· Journal of Agricultural and...· 0 citations
Hemiptera pests damage crops and transmit viruses through piercing-sucking mouthparts, causing enormous economic losses and inducing resistance to insecticides. Novel insecticides are critical to combat rising resistance. Nicotinamidase, a newly validated target present in the insect chordotonal organ, has attracted attention. A series of novel sulfonyl, carbonyl, and amide group-based 4-(trifluoromethyl)nicotinamide derivatives was designed using the prodrug strategy and an intermediate derivatization method. Bioactivity assays indicated that most compounds possessed enhanced insecticidal activity. B-38 exhibited outstanding lethality against Sitobion avenae (LC50 = 0.710 mg/L), outperforming that of flonicamid (LC50 = 13.7 mg/L). The 3D-QSAR model revealed that the introduction of electron-withdrawing groups at the R3 position and electron-donating groups at the R4 positions, respectively, enhanced insecticidal potency. DFT calculations suggested that propargyl and imide groups may be essential for bioactivity. This study provides fundamental insights for developing green and efficient insecticides.
Ying Bian, Li-Xia Zhao, Tiansong Li et al.· Journal of Agricultural and...· 0 citations