Design, Synthesis, and Herbicidal Activity of Pyrazole Amide Derivatives as Potential Transketolase Inhibitors.

The design and synthesis of new herbicidal active compounds based on a new target are of great significance for the development of new herbicides. Transketolase (TK) plays a key role in the Calvin cycle of plant photosynthesis and has been confirmed as a potential candidate target to develop and discover new herbicides. To obtain compounds with ultraefficient targeting of TK, a series of pyrazole amide derivatives were designed and synthesized through structural optimization for lead compound based on TK as the new target. The bioassay results showed that compounds and displayed a highly inhibitory effect with the root inhibition of about 90% against () and 80% against () and () by the small cup method, which was better than the positive control mesotrione and nicosulfuron. Furthermore, compounds and exhibited an excellent inhibitory effect with the inhibition of about 80% (against ) and over 80% (against ) at the dosage of 150 g of active ingredient/ha by the foliar spray method. The TK enzyme activity inhibition test showed that the inhibition effect of target compounds against TK was consistent with the results of herbicidal activities. Also, molecular docking analysis showed that compounds and went deep into the active cavity of TK, bound to TK by a strong interaction, and might act on the enzyme TK. Above of all, compounds and are promising herbicide lead compounds targeting TK. Hence, they could be developed into more efficient herbicides by further structural optimization.