Searching for new alternatives to antibiotic treatments is crucial to surmount the multidrug-resistant bacteria. In this work, the antimicrobial activity of synthetic imidazolidines was evaluated as well as their modulating effect on the resistance to fluoroquinolones in a S. aureus strain (SA-1199B), which overexpresses the norA gene that encodes the NorA efflux pump. Results showed weak antimicrobial activity (512 μg mL^-1) for two fluorobenzylidene derivatives against this bacterial strain, while the other benzylidene derivatives were inactive. Despite this fact, both fluorinated compounds were able to enhance the activity of norfloxacin and ciprofloxacin against SA–1199B up to 6.4– and 3.2-fold, respectively. In addition, both derivatives potentiated the action of ethidium bromide against this strain, suggesting that the modulating effect probably involves the inhibition of the NorA efflux pump, which is in concordance with the fluorimetic assays and molecular docking analyses performed in this work.

寻找新的抗生素治疗替代方法对于克服耐多药细菌至关重要。在这项工作中，评估了合成咪唑烷的抗菌活性及其对金黄色葡萄球菌菌株（SA-1199B）对氟喹诺酮类药物耐药性的调节作用，该菌株过表达编码NorA外排泵的norA基因。结果显示抗微生物活性弱（512μgmL ^{- 1}）中有两个针对该细菌菌株的氟亚苄基衍生物，而其他亚苄基衍生物则没有活性。尽管有这个事实，两种氟化化合物都能将诺氟沙星和环丙沙星的抗SA-1199B活性分别提高至6.4和3.2倍。此外，这两种衍生物均增强了溴化乙锭对该菌株的作用，表明调节作用可能涉及抑制NorA外排泵，这与本工作中进行的荧光分析和分子对接分析一致。