Discovery of Mesoionic Derivatives Containing a Dithioacetal Skeleton as Novel Potential Antibacterial Agents and Mechanism Research.

In this study, the design and synthesis of novel pyrido[1,2-]pyrimidinone mesoionic derivatives incorporating dithioacetal structures were carried out. The three-dimensional quantitative structure-activity relationship (3D-QSAR) model was built according to the EC values and directed the synthesis of compound . The biological activity test against pv. () and pv. () indicated that compound showed good antibacterial activity with EC values of 10.9 and 17.5 mg/L, which were lower than the EC values of bismerthiazol (29.3 and 39.8 mg/L) and thiodiazole copper (64.8 and 78.1 mg/L). Furthermore, the in vivo antibacterial activity against bacterial leaf blight (BLB) and bacterial leaf streak (BLS) revealed that the protective activity of compound was 43.9 and 41.7%, respectively, which was better than the protective activity of thiodiazole copper (40.6 and 35.0%). In addition, the protective activity against bacterial leaf blight of compound was associated with the increasing rice defensive enzyme activity and the upregulation of proteins involved in oxidative phosphorylation. Moreover, compound could upregulate the expression of complex I (nicotinamide adenine dinucleotide hydrogen (NADH) dehydrogenase) in the oxidative phosphorylation pathway, which was verified by complex I activity evaluation.