Design, synthesis and evaluation of quinolone quaternary ammonium antibacterial agent with killing ability to biofilm.

Staphylococcus aureus (S. aureus) is the most common and widely distributed pathogenic bacterium. The problem of methicillin-resistant Staphylococcus aureus (MRSA) caused by the widespread use of antibiotics is particularly severe. In addition, S. aureus can resist antibiotics by forming biofilms, making clinical treatment difficult. A series of antimicrobial quinolone-based quaternary ammonium compounds were designed and synthesized. Among them, the optimal compound 3e showed the strongest activity against S. aureus, and it had relatively low hemolytic toxicity and cytotoxicity. Compound 3e has excellent bactericidal performance, capable of quickly and thoroughly sterilizing. In continuous sub-lethal concentration bacterial passage culture, no bacterial resistance tendency caused by 3e was found. Moreover, 3e can exert a significant level of activity in blood components and still has a period of suppression on bacteria after the drug is removed. Encouragingly, 3e has a certain bactericidal potential against bacteria with high concentration and high tolerance. It has shown strong bactericidal effects when fighting against persister bacteria and biofilms in vitro. Mechanism research indicates that 3e exerts its antimicrobial action through related membrane activity and is related to membrane components phosphatidylglycerol (PG) and cardiolipin (CL). In addition, 3e can also bind to bacterial DNA.