Abstract The NorA efflux pump lowers intracellular fluoroquinolone concentrations by expelling antibiotics through the membrane of Staphylococcus aureus. We identified 3-aryl-4- methyl-2-quinolin-2-ones as compounds able to restore the activity of the NorA substrate, ciprofloxacin, against resistant S. aureus strains, and acting as efflux pump inhibitors (EPI). In particular, 5-hydroxy-7-methoxy-4-methyl-3-phenylquinolin-2-one (6 c) presents both ...
