Design, Synthesis, and Biological Evaluation of Novel Purine Derivatives as Herbicide Safeners

Mesosulfuron-methyl, an inhibitor of acetolactate synthase (ALS), has been extensively used in wheats. However, it can damage wheat ( Triticum aestivum ) and even lead to crop death. Herbicide safeners selectively shield crops from such damage without compromising weed control. To mitigate the phytotoxicity of mesosulfuron-methyl in crops, several purine derivatives were developed based on active substructure splicing. The synthesized title compounds underwent thorough characterization using infrared spectroscopy, 1 H nuclear magnetic resonance ( 1 H NMR), 13 C nuclear magnetic resonance ( 13 C NMR), and high-resolution mass spectrometry. We evaluated chlorophyll and glutathione contents as well as various enzyme activities to evaluate the safer activity of these compounds. Compounds III-3 and III-7 exhibited superior activity compared with the safener mefenpyr-diethyl. Molecular structure analysis, along with predictions of absorption, distribution, metabolism, excretion, and toxicity, indicated that compound III-7 shared pharmacokinetic traits with the commercial safener mefenpyr-diethyl. Molecular docking simulations revealed that compound III-7 competitively bound to the ALS active site with mesosulfuron-methyl, elucidating the protective mechanism of the safeners. Overall, this study highlights purine derivatives as potential candidates for novel safener development.