Synthesis of Novel Acetoguanidine Derivatives and Their Biological Activity Against Xanthomonas oryzae

Rice bacterial leaf blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is a severe bacterial disease that can lead to fatal damage to rice plants when infection is severe. In this study, an active splicing strategy was employed to design and synthesize 36 novel acetoguanidine derivatives. The structures of the target compounds were confirmed by ¹H NMR and ¹³C NMR spectroscopy, and their antibacterial activity against Xoo was evaluated. Among them, compounds E5, E6, and E9 exhibited significant inhibitory effects on Xoo, with EC₅₀ values of 17.27, 18.15, and 19.35 μg/mL, respectively. Further investigation into the preliminary mechanism of action of E5 revealed that treatment with this compound notably influenced reactive oxygen species (ROS) production. Additionally, safety assessments conducted on earthworms and silkworms indicated that E5 possesses favorable biosafety. These findings suggest that E5 is a promising candidate for antibacterial agents, laying a theoretical foundation for the development of small-molecule inhibitors.