No abstract

Controllable and on‐demand delivery of supramolecular systems have received considerable attention in modern agricultural management, especially for managing intractable plant diseases. Here, an intelligent photoresponsive pesticide delivery system is reported based on β‐cyclodextrin (β‐CD) and azobenzene, which overcomes the resistance of phytopathogens caused by the irrational use of conventional pesticides. Antibacterial bioassays illustrated that designed azobenzene derivative 3a possesses the most efficient bioactivity with EC50 values of 0.52–25.31 µg mL−1 toward three typical phytopathogens. Moreover, the assembly of the supramolecular binary complex 3a@β‐CD is successfully elucidated and displays exceptional inhibitory activity on biofilm formation. Of note, this supramolecular binary complex significantly improves the water solubility, foliar surface wettability, and shows marked light‐responsive properties. In vivo anti‐Xoo assays reveal that 3a@β‐CD has excellent control efficiency (protective activity: 51.22%, curative activity: 48.37%) against rice bacterial blight pathogens, and their control efficiency can be elevated to values of 55.84% (protective activity) and 52.05% (curative activity) by UV–vis exposure. In addition, the 3a@β‐CD are non‐toxic toward various non‐target organisms. This study therefore offers new insights into the potential of host‐guest complexes as a feasible pesticide discovery strategy characterized by a safe, biocompatible, light‐responsive release, and antibiofilm properties for overcoming intractable plant bacterial diseases.

Supramolecular chemistry provides huge potentials and opportunities in agricultural pest management. In an attempt to develop highly bioactive, eco-friendly, and biocompatible supramolecular complexes for managing intractable plant bacterial diseases, herein, a type of interesting adamantane-functionalized 1,3,4-oxadiazole was rationally prepared to facilitate the formation of supramolecular complexes via β-cyclodextrin−adamantane host−guest interactions. Initial antibacterial screening revealed that most of these adamantane-decorated 1,3,4-oxadiazoles were obviously bioactive against three typically destructive phytopathogens. The lowest EC 50 values could reach 0.936 (III 18 ), 0.889 (III 18 ), and 2.10 (III 19 ) μg/mL against the corresponding Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas axonopodis pv. citri (Xac), and Pseudomonas syringae pv. actinidiae (Psa). Next, the representative supramolecular binary complex III 18 @β-CD (binding mode 1:1) was successfully fabricated and characterized by 1 H nuclear magnetic resonance (NMR), isothermal titration calorimetry (ITC), high-resolution mass spectrometry (HRMS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Eventually, correlative water solubility and foliar surface wettability were significantly improved after the formation of host−guest assemblies. In vivo antibacterial evaluation found that the achieved supramolecular complex could distinctly alleviate the disease symptoms and promote the control efficiencies against rice bacterial blight (from 34.6−35.7% (III 18 ) to 40.3−43.6% (III 18 @β-CD)) and kiwi canker diseases (from 41.0−42.3% (III 18 ) to 53.9−68.0% (III 18 @β-CD)) at 200 μg/mL (active ingredient). The current study can provide a feasible platform and insight for constructing biocompatible supramolecular assemblies for managing destructive bacterial infections in agriculture.

A safe, biocompatible, and stimuli-responsive cucurbit [7]urilmediated supramolecular bactericidal nanoparticle was fabricated by encapsulating a highly bioactive carbazole-decorated imidazolium salt (A 1 , EC 50 = 0.647 μg/mL against phytopathogen Xanthomonas oryzae pv oryzae) into the host cucurbit[7]uril (CB[7]), thereby leading to self-assembled topographies from microsheets (A 1 ) to nanospheroidal architectures (A 1 @ CB[7]). The assembly behaviors were elucidated by acquired single-crystal structures, 1 H NMR, ITC, and X-ray powder diffraction experiments. Complex A 1 @CB[7] displayed lower phytotoxicity and could efficiently switch on its potent antibacterial ability via introducing a simple competitor 1-adamantanamine hydrochloride (AD). In vivo antibacterial trials against rice bacterial blight revealed that A 1 @CB[7] could relieve the disease symptoms after being triggered by AD and provide a workable control efficiency of 42.6% at 100 μg/mL, which was superior to bismerthiazol (33.4%). These materials can provide a viable platform for fabricating diverse stimuli-responsive supramolecular bactericides for managing bacterial infections with improved safety.

One new aliphatic ketone alcohol, 15,17-dione-16-hentriacontanol (1), with fifteen known compounds (2-16) were isolated from the ethanolic extract of the whole dried plant of Lepidium latifolium. The antibacterial activities (using minimum inhibitory concentrations (MIC) detection method), the antioxidant activities (using 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and pyrogallol), and the antiproliferative activities (using 3-(4,5dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) method) against three human cancer cell lines were evaluated. The results showed that compounds 2, 9, 10 and 11 with phenolic hydroxyl groups have good antibacterial and DPPH scavenging activities. Compounds 2, 12 and 13, which contain -NH groups have the highest scavenging rates of superoxide anions. The compounds of long-chain alkane containing hydroxyl groups have potent inhibitory activity against MGC-803, HepG2 and T24 cancer cells. The experimental content of this paper enriches the related research of L. latifolium, and greatly expands the market application value of the plant.