In this investigation, to determine their potential as specific antibacterial agents, Schiff's bases (LT-SB1-23 and SB1-SB12) and novel quinoline-isatin hybrids were subjected to microbiological testing. The in-vitro screening against bacterial strains (Escherichia coli, Enterococcus faecalis, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella typhi) exhibited their antibacterial potential with many of the compounds showing inhibition range of 90–100 % at 200 μg/mL, against most of the tested strains. The MIC values of some of the compounds showed good antibacterial efficacy with values ranging from 32 to 128 μg/mL. Their bacterial growth inhibitory potential was further supported by disk diffusion and growth curve assays. Interestingly, one of the Schiff's bases (LT-SB7) displayed strong synergistic activity against E. coli and S. typhi with 16–64 folds reduction in MIC values. Additionally, it exhibited up to 85 % suppression of biofilm at ½MIC against AA209 environmental bacterial isolate and reduced the development of multidrug-resistant bacterial isolates. Promising compound LT-SB7 underwent 100 ns molecular dynamics simulations with biofilm-causing protein (PDB ID: 7C7U) to assess conformational changes and complex stability. Overall, this study identified compounds as effective antibacterial alternatives for the future.

中文翻译：

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4-氨基喹啉-Isatin分子杂交体和希夫碱作为有前途的抗菌剂的合成和机理研究


在这项研究中，为了确定它们作为特异性抗菌剂的潜力，对 Schiff 的碱（LT-SB1-23 和 SB1-SB12）和新型喹啉-靛红杂交种进行了微生物学测试。针对细菌菌株（大肠杆菌、粪肠球菌、枯草芽孢杆菌、金黄色葡萄球菌、铜绿假单胞菌和伤寒沙门氏菌）的体外筛选显示出其抗菌潜力，许多化合物在 200 μg/mL 时显示出 90-100% 的抑制范围，针对大多数测试菌株。一些化合物的 MIC 值显示出良好的抗菌效果，值范围为 32 至 128 μg/mL。他们的细菌生长抑制潜力得到了纸片扩散和生长曲线测定的进一步支持。有趣的是，希夫碱基之一 （LT-SB7） 对大肠杆菌和伤寒沙门氏菌表现出很强的协同活性，MIC 值降低了 16-64 倍。此外，它在 1/2MIC 下对 AA209 环境细菌分离物的生物膜抑制高达 85%，并减少了多重耐药细菌分离物的开发。有前途的化合物 LT-SB7 对生物膜致病蛋白 （PDB ID： 7C7U） 进行了 100 ns 分子动力学模拟，以评估构象变化和复合物稳定性。总体而言，这项研究确定了化合物是未来有效的抗菌替代品。