Design, synthesis, antifungal activities and binding mode with succinate dehydrogenase receptor of quinazolinone oxime ether derivatives

In order to discover novel compounds with high fungicidal activities, fluopyram was used as a control, based on the previous discovery of a novel nitromethylquinazolinone skeleton, 25 novel quinazolinone oxime ether derivatives were designed and synthesized by intermediate derivatization and sub-structural combination methods. Their structures were characterized by ¹H NMR, ¹³C NMR and HR-EI-MS spectral data. The preliminary in vivo antifungal evaluation results showed that compounds A19 and A25 were 43.74% and 42.46% control Fusarium graminearum at a concentration of 500 mg/L, respectively. However, the antifungal activities were much lower than that of fluopyram. The differences in physicochemical properties and binding mode with succinate dehydrogenase (SDH) receptor between these compounds and fluopyram may be the major factor which reduced the antifungal activities.