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, 1H nuclear magnetic resonance (1H NMR), 13C nuclear magnetic resonance (13C 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.