Design, Synthesis, and Bioactivity of Novel 2-(Arylformyl)cyclohexane-1,3-dione Derivatives as HPPD Inhibitors

Basing target enzyme study the enantioselective bioactivity action mechanism of flusulfinam, a novel HPPD inhibitor herbicide

Flusulfinam is a novel chiral amide herbicide widely used for controlling annual weeds in rice paddies. However, the mechanism underlying their enantioselective herbicidal activity remain unclear. Herein, it was found that flusulfinam enantiomers, similar to typical HPPD inhibitor mesotrione, reduced chlorophyll and carotenoid levels, decreased HPPD enzyme activity, and upregulated gene expression. Additionally, homogentisate supplementation alleviated the bleaching symptoms caused by flusulfinam and all these results validate that flusulfinam is indeed an HPPD inhibitor. To further investigate the mechanism of enantioselectivity, molecular docking was used and showed that R-flusulfinam (-6.55 kcal/mol) had higher binding energy than S-flusulfinam (-5.60 kcal/mol), due to more stable hydrogen bonds with Gln293. After mutating Gln293 to His, the IC50 values for R-flusulfinam and S-flusulfinam on MutQ293H were 0.73 mg/L and 0.11 mg/L, respectively, indicating swapped enantioselective inhibition compared to AtHPPD, with IC50 values of 0.52 mg/L and 1.93 mg/L, respectively. The Microscale Thermophoresis assay further revealed that the dissociation constant (Kd) for MutQ293H with R-flusulfinam was 20.40 ± 4.19 μM, similar to the Kd value of 15.63 ± 4.51 μM for S-flusulfinam. The findings reveal that mutation of the Gln293 residue in the AtHPPD enzyme significantly altered its enantioselective inhibition by flusulfinam. This study is the first to verify the mode of action of flusulfinam and identifies that Gln293 may play a key role in flusulfinam enantioselectivity in the AtHPPD, laying the foundation for future HPPD inhibitor development based on flusulfinam.

4-Hydroxyphenylpyruvate Dioxygenase Inhibitors: From Molecular Design to Synthesis

Weed resistance is a critical issue in crop production. Among the known herbicides, 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitors are crucial for addressing weed resistance. HPPD inhibitors constitute a pivotal aspect of contemporary crop protection strategies. The advantages of these herbicides are their broad weed spectrum, flexible application, and excellent compatibility with other herbicides. They also exhibit satisfactory crop selectivity and low toxicity and are environmentally friendly. An increasing number of new HPPD inhibitors have been designed by combining computer-aided drug design with conventional design approaches. Herein, the molecular design and structural features of innovative HPPD inhibitors are reviewed to guide the development of new HPPD inhibitors possessing an enhanced biological efficacy.

Design, Synthesis, and Herbicidal Activity of Natural Naphthoquinone Derivatives Containing Diaryl Ether Structures

Photosynthesis system II (PS II) is an important target for the development of bioherbicides. In this study, a series of natural naphthoquinone derivatives containing diaryl ether were designed and synthesized based on the binding model of lawsone and PS II D1. Bioassays exhibited that most compounds had more than 80% inhibition of Portulaca oleracea and Echinochloa crusgalli roots at a dose of 100 μg/mL and compounds B4, B5, and C3 exhibited superior herbicidal activities against dicotyledonous and monocotyledon weeds to commercial atrazine. In particular, compound B5 exhibited excellent herbicidal activity at a dosage of 150 g a.i./ha. In addition, compared with atrazine, compound B5 causes less damage to crops. Molecular docking studies revealed that compound B5 effectively interacted with Pisum sativum PS II D1 via diverse interaction models, such as π-π stacking and hydrogen bonds. Molecular dynamics simulation studies and chlorophyll fluorescence measurements revealed that compound B5 acted on PS II. This is the first report of natural naphthoquinone derivatives targeting PS II and compound B5 may be a candidate molecule for the development of new herbicides targeting PS II.

Ferulic Acid Dimers as Potential Antiviral Agents by Inhibiting TMV Self-Assembly

A series of ferulic acid dimers were designed, synthesized, and evaluated for anti-TMV activity. Biological assays demonstrated that compounds A6, E3, and E5 displayed excellent inactivating against tobacco mosaic virus (TMV) with EC50 values of 62.8, 94.4, and 85.2 μg mL-1, respectively, which were superior to that of ningnanmycin (108.1 μg mL-1). Microscale thermophoresis indicated that compounds A6, E3, and E5 showed strong binding capacity to TMV coat protein with binding affinity values of 1.862, 3.439, and 2.926 μM, respectively. Molecular docking and molecular dynamics simulation revealed that compound A6 could firmly bind to the TMV coat protein through hydrogen and hydrophobic bonds. Transmission electron microscopy and self-assembly experiments indicated that compound A6 obviously destroyed the integrity of the TMV particles and blocked the virus from infecting the host. This study revealed that A6 can be used as a promising leading structure for the development of antiviral agents by inhibiting TMV self-assembly.

Synthesis, and Insecticidal Activities of Propargyloxy-Diphenyl Oxide-Sulfonamide Derivatives

Agricultural pests are the primary contributing factor to crop yield reduction, particularly in underdeveloped regions. Despite the significant efficacy of pesticides in pest control, their extensive use has led to the drug-fast of insecticide resistance. Developing of new environmentally friendly plant-based pesticides is an urgent necessity. In this study, a series of diaryl ether compounds containing propargyloxy and sulfonamide groups were designed. The synthesis of these 36 compounds primarily relied on nuclear magnetic resonance for structure determination, while single-crystal X-ray diffraction was employed for certain compounds. Meanwhile, the insecticidal activities against Mythimna separata were also assessed. Some of the compounds exhibited significantly enhanced activity, the LC50 value of the highest activity compound TD8 (0.231 mg/mL) demonstrating respective increases by 100-fold compared to the plant pesticide celangulin V (23.9 mg/mL), and a 5-fold increase with the positive control L-1 (1.261 mg/mL). The interaction between the target compound and the target, as well as the consistency of the target, were verified through symptomological analysis and molecular docking. The structure-activity relationships were also conducted. This study offered a novel trajectory for the advancement and formulation of future pesticides.