Design, Synthesis, and Bioactivity of Novel Coumarin-3-carboxylic Acid Derivatives Containing a Thioether Quinoline Moiety.

A series of coumarin-3-carboxylic acid derivatives containing a thioether quinoline moiety were designed and synthesized. The structures of these compounds were determined using H NMR, C NMR, and HRMS. The antibacterial activity of the compounds was evaluated against pv (), (), and (). The results showed that most of the compounds exhibited significant antibacterial activity against these pathogens. Particularly, compound A9 demonstrated potent activity against and , with EC values of 11.05 and 8.05 μg/mL respectively. In addition, A9 indicated strong protective and curative effects against , with efficacy rates of 61.50 and 54.86%, respectively, surpassing those of the positive control thiodiazole copper. The scanning electron microscopy observations revealed that treatment of cells with A9 at a concentration of 2EC resulted in a curved and sunken cell morphology, along with destroyed cell membrane integrity. Additionally, the motility and exopolysaccharide production of were inhibited, and biofilm formation was prevented. Consequently, these newly developed derivatives of coumarin-3-carboxylic acid, incorporating the thioether quinoline moiety, hold promise as potential templates for the development of innovative antibacterial agents.