Discovery and biological evaluation of nitrofuranyl-pyrazolopyrimidine hybrid conjugates as potent antimicrobial agents targeting and methicillin-resistant .

Nitrofuran and pyrazolopyrimidine-based compounds possess a broad antimicrobial spectrum including Gram-positive and Gram-negative bacteria. In the present work, a series of conjugates of these scaffolds was synthesized and evaluated for antimicrobial activity against and methicillin-resistant (MRSA). Many compounds showed MIC values of ≤2 μg ml, with compound 35 demonstrating excellent activity (MICs: 0.7 and 0.15 μg ml against and MRSA, respectively) and safety up to 50 μg ml in HepG2 cells. Compound 35 also exhibited no hemolytic activity, biofilm eradication, and effectiveness against efflux-pump-overexpressing strains (NorA, TetK, MsrA) without resistance development. It showed synergistic effects with vancomycin () and rifampicin (MRSA). Mechanistic studies revealed that compound 35 exhibits good membrane-targeting abilities, as evidenced by DAPI/PI staining and scanning electron microscopy (SEM). In an intracellular model, it reduced bacterial load efficiently in both and MRSA strains. With a strong profile, compound 35 demonstrated favorable oral pharmacokinetics at 30 mg kg and potent anti-MRSA activity, highlighting its potential against antibiotic-resistant infections.