Synthesis and Biological Activity Evaluation of Novel <em>β</em>-Substituted Nitromethylene Neonicotinoid Analogues

The structure-based design and synthesis of a series of novel neonicotinoid analogues are described. The novel neonicotinoid analogues were designed based upon the reaction of enamine derivatives with electron-withdrawing <em>β</em>-substituents with electrophilic thiocyanogen reagents. These compounds were characterized by spectroscopic methods. Bioassays indicated that some of the synthesized compounds exhibited excellent bioactivity against cowpea aphids (<em>Aphis craccivora</em>). The LC<sub>50</sub> values of compounds <strong>7</strong>, <strong>9</strong>, <strong>12</strong>, <strong>13</strong>, <strong>15</strong>, <strong>17</strong>, <strong>19</strong>, <strong>20</strong> and commercial imidacloprid were 0.01567, 0.00974, 0.02494, 0.01893, 0.02677, 0.01778, 0.0220, 0.02447 and 0.03502 mmol L<sup>−1</sup>, respectively, which suggested that they could be used as leads for future development of new insecticides

A Water-Based Nanoformulation for the Pesticide Delivery of Lambda-Cyhalothrin with High Retention on Foliage by Using Aerosol OT Vesicles as Carriers

Lambda-cyhalothrin (LC) is a highly efficient broad-spectrum pesticide in agricultural production, yet its application is limited by weak solubility and poor adhesion to foliage. To develop effective utilization and enhance pesticide adhesion to targets, LC was loaded into a water-based vesicle system formed by aerosol OT (AOT) with a double hydrocarbon chain. The LC-loaded AOT vesicles (LC-AOT) had a high encapsulation efficiency (EE) of 97%. Dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements showed that LC-AOT vesicles had uniform morphology with a particle size of around 200 nm. The zeta potential and polydispersity index (PDI) values of LC-AOT vesicles were −70.3 mV and 0.20, respectively. Compared with commercial LC formulations, LC-AOT vesicles exhibited better wettability and retention on cabbage leaves. In addition, an insecticidal activity study demonstrated that LC-AOT vesicles exhibited prominent toxicity against Aphis craccivora. This research provided a valuable approach for solving problems of low utilization and little deposition on foliage for water-insoluble LC pesticides

Enhanced Insecticidal Effect and Interface Behavior of Nicotine Hydrochloride Solution by a Vesicle Surfactant

Nicotine hydrochloride (NCT) has a good control effect on hemiptera pests, but its poor interfacial behavior on the hydrophobic leaf leads to few practical applications. In this study, a vesicle solution by the eco-friendly surfactant, sodium diisooctyl succinate sulfonate (AOT), was prepared as the pesticide carrier for NCT. The physical chemical properties of NCT-loaded AOT vesicles (NCT/AOT) were investigated by techniques such as dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and cryogenic transmission electron microscopy (cryo-TEM). The results showed that the pesticide loading and encapsulation efficiency of NCT/AOT were 10.6% and 94.8%, respectively. The size of NCT/AOT vesicle was about 177 nm. SAXS and surface tension results indicated that the structure of the NCT/AOT vesicle still existed with low surface tension even after being diluted 200 times. The contact angle of NCT/AOT was always below 30°, which means it could wet the surface of the cabbage leaf well. Consequently, NCT/AOT vesicles could effectively reduce the bounce of pesticide droplets. In vitro release experiments showed that NCT/AOT vesicles had sustained release properties; 60% of NCT in NCT/AOT released after 24 h, and 80% after 48 h. Insecticidal activity assays against aphids revealed that AOT vesicles exhibited insecticidal activity and could have a synergistic insecticidal effect with NCT after the loading of NCT. Thus, the NCT/AOT vesicles significantly improved the insecticidal efficiency of NCT, which has potential application in agricultural production activities

Discovery of Potential Neonicotinoid Insecticides by an Artificial Intelligence Generative Model and Structure-Based Virtual Screening

The identification of neonicotinoid insecticides bearing novel scaffolds is of great importance for pesticide discovery. Here, artificial intelligence-based tools and virtual screening strategy were integrated to discover potential leads of neonicotinoid insecticides. A deep generative model was successfully constructed using a recurrent neural network combined with transfer learning. The model evaluation showed that the pretrained model could accurately grasp the SMILES grammar of drug-like molecules and generate potential neonicotinoid compounds after transfer learning. The generated molecules were evaluated by hierarchical virtual screening, hits were subjected to a similarity search, and the most similar structures were purchased for the bioassay. Compounds A2 and A5 displayed 52.5 and 50.3% mortality rates against Aphis craccivora at 100 mg/L, respectively. The docking study indicated that these two compounds have similar binding modes to neonicotinoids, which were verified by further molecular dynamics simulations

Bi-aryl rotation in phenyl-dihydroimidazoquinoline catalysts for kinetic resolution of arylalkyl carbinols

Chiral nucleophilic catalysts, 6-aryl-phenyl-dihydroimidazoquinolines (PIQs), were designed, synthesised and applied to the kinetic resolution of arylalkyl carbinols with very high selectivity (S) factors (up to 530).</p

Avermectin induced DNA damage to the apoptosis and autophagy in human lung epithelial A549 cells

Avermectin (AVM), as a biological insecticide, is widely used in agriculture and forestry production globally. However, inhalation of AVM may pose a risk, and the lung is the direct target, but the cytotoxicity of AVM on human lung cells is still unclear. Here, we attempted to elucidate the cytotoxic effect and molecular mechanism of AVM on human lung A549 cells. The results indicated that AVM inhibits cell proliferation, and enhances programmed cell death (apoptosis and autophagy). In addition, we found the AVM-treated cells showed an obvious drop in mitochondrial membrane potential and LC3-I/II, increased ROS production, DNA double-strand breaks, caspase-3/9 activated, PARP cleaved, cytochrome c and Bax/Bcl-2 content rise. The results showed that AVM induced mitochondria-related apoptosis and autophagy in lung A549 cells. These results indicate that AVM can pose a potential threat to human health by inducing DNA damage and programmed cell death

Construction and Characterization of a Novel Sustained-Release Delivery System for Hydrophobic Pesticides Using Biodegradable Polydopamine-Based Microcapsules

Microcapsule formulations have been highly desirable and widely developed for effective utilization of pesticides and environmental pollution reduction. However, commercial and traditional microcapsule formulations of λ-cyhalothrin (LC) were prepared by complicated synthesis procedures and thereby specific organic solvents were needed. In this work, LC was encapsulated into versatile, robust, and biodegradable polydopamine (PDA) microcapsules by self-polymerization of dopamine. LC-loaded PDA microcapsules were characterized by transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and thermogravimetric analysis measurements (TGA). LC-loaded PDA microcapsules have uniform morphology with nanoscale, decent LC loading content (>50.0% w/w), and good physicochemical stability and sustained release properties. The bioassay against housefly (Musca domestica) showed that the bioactivity and long-term efficiency of LC-loaded PDA microcapsules was superior to that of the commercial formulation. All of these results demonstrated that LC-loaded PDA microcapsules could be applied as a commercial LC microcapsule formulation with fewer environmental side effects and higher effective delivery