Quinoline-based anti-MRSA agents: Current development, structure-activity relationships, and mechanisms

Methicillin-resistant Staphylococcus aureus (MRSA), the most common pathogen in hospital and community environments, can cause serious and even fatal infections. The antibiotics currently used for clinical treatment of MRSA have developed resistance, and there is an urgent need to develop new antimicrobials to treat infections caused by MRSA strains. Quinoline analogues play an important role in the development of antimicrobials. Herein, we discussed the current development of antibacterial activities of quinoline analogues, mainly for anti-MRSA activity, and their structure-activity relationships (SARs) from the perspective of using the quinoline nucleus to search for novel potential anti-MRSA candidates. Additionally, the mechanisms of some representative quinoline analogues against MRSA were clarified. Altogether, this review could provide further insights for the rational development of quinoline-based antibacterial drugs, especially against MRSA.

Discovery of thiosemicarbazone derivatives as effective New Delhi metallo-β-lactamase-1(NDM-1) inhibitors against NDM-1 producing clinical isolates

New Delhi metallo-b-lactamase-1(NDM-1)is capable of hydrolyzing nearly allβ-lactam antibiotics,posing an emerging threat to public health.There are currently less effective treatment options for treating NDM-1 positive"superbug",and no promising NDM-1 inhibitors were used in clinical practice.In this study,structure eactivity relationship based on thiosemicarbazone derivatives wassystematically characterized and their potential activities combined with meropenem(MEM)were evaluated.Compounds 19 bg and 19 bh exhibited excellent activity against 10 NDM-positive isolate clinical isolates in reversing MEM resistance.Further studies demonstrated compounds 19 bg and 19 bh were uncompetitive NDM-1 inhibitors with Ki Z 0.63 and 0.44 mmol/L,respectively.Molecular docking speculated that compounds 19 bg and 19 bh were most likely to bind in the allosteric pocket which would affect the catalytic effect of NDM-1 on the substrate meropenem.Toxicity evaluation experiment showed that no hemolysis activities even at concentrations of 1000 mg/m L against red blood cells.In vivo experimental results showed combination of MEM and compound 19 bh was markedly effective in treating infections caused by NDM-1 positive strain and prolonging the survival time of sepsis mice.Our finding showed that compound 19 bh might be a promising lead in developing new inhibitor to treat NDM-1 producing superbug.