Safeners Improve Maize Tolerance under Herbicide Toxicity Stress by Increasing the Activity of Enzymes in Vivo

A built-in self-calibrating luminescence sensor based on RhB@Zr-MOF for detection of cations, nitro explosives and pesticides

A RhB@Zr-MOF composite with dual-emission properties was successfully constructed, which comprises a zirconium-based metal-organic framework and the luminescent dye molecule, Rhodamine B (RhB), embedded via the encapsulation method. The fluorescence intensity ratio of the two emissions was found to be ca. 370 nm/590 nm for RhB@Zr-MOF. The fluorescence intensity values of the two emissions of RhB@Zr-MOF can also be affected by the structures of analytes containing different organic groups. Due to the existence of the dual-emission properties in RhB@Zr-MOF, the relative fluorescence intensity of the emission peaks was introduced as a detection index instead of absolute fluorescence intensity. RhB@Zr-MOF, which possesses the characteristics of a built-in self-calibrating fluorescence sensor, was investigated for detecting cations, nitroaromatics and pesticides. Aside from high sensitivity and selectivity, recyclability is the most important property for sensing pesticides. This work shows that RhB@Zr-MOF can maintain its stability after 5 cycles of detecting nitenpyram, with LOD of 0.2 μM. These results demonstrate that dye@MOFs with dual-emission properties can be employed as multifunctional fluorescence sensors for different types of analytes, and that RhB@Zr-MOF provides a new paradigm for analyte sensing.

Design, Synthesis, and Herbicidal Activity of Novel Diphenyl Ether Derivatives Containing Fast Degrading Tetrahydrophthalimide

To seek new protoporphyrinogen oxidase (PPO) inhibitors with better biological activity, a series of novel diphenyl ether derivatives containing tetrahydrophthalimide were designed based on the principle of substructure splicing and bioisomerization. PPO inhibition experiments exhibited that 6c is the most potential compound, with the half-maximal inhibitory concentration (IC₅₀) value of 0.00667 mg/L, showing 7 times higher activity than Oxyfluorfen (IC₅₀ = 0.0426 mg/L) against maize PPO and similar herbicidal activities to Oxyfluorfen in weeding experiments in greenhouses and field weeding experiments. In view of the inspected bioactivities, the structure-activity relationship (SAR) of this series of compounds was also discussed. Crop selection experiments demonstrate that compound 6c is safe for soybeans, maize, rice, peanuts, and cotton at a dose of 300 g ai/ha. Accumulation analysis experiments showed that the accumulation of 6c in some crops (soybeans, peanuts, and cotton) was significantly lower than Oxyfluorfen. Current work suggests that compound 6c may be developed as a new herbicide candidate in fields.

Design, Synthesis, and Biological Activity of Novel Diazabicyclo Derivatives as Safeners

Herbicide safeners selectively protect crops from herbicide damage without reducing the herbicidal efficiency on target weed species. The title compounds were designed by the intermediate derivatization approach and fragment splicing to exploit novel potential safeners. A total of 31 novel diazabicyclo derivatives were synthesized by the microwave-assistant method using isoxazole-4-carbonyl chloride and diazabicyclo derivatives. All synthetic compounds were confirmed by infrared, ¹H and ¹³C nuclear magnetic resonance, and high-resolution mass spectrometry. The bioassay results demonstrated that most of the title compounds could reduce the nicosulfuron phytotoxicity on maize. The glutathione S-transferase (GST) activity in vivo was assayed, and compound 4(S15) revealed an inspiring safener activity comparable to commercialized safeners isoxadifen-ethyl and BAS-145138. The molecular docking model exhibited that the competition at the active sites of target enzymes between compound 4(S15) and nicosulfuron was investigated with respect to herbicide detoxification. The current work not only provided a powerful supplement to the intermediate derivatization approach and fragment splicing in design pesticide bioactive molecules but also assisted safener development and optimization.