Antibacterial and Antibiofilm Efficacy of a Synthetic Nitrofuranyl Pyranopyrimidinone Derivative against Methicillin-Resistant Staphylococcus aureus

Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) is a major public health concern due to its multidrug resistance and robust biofilm formation, which contribute to persistent infections and treatment failures. Novel antibiofilm agents are urgently needed to combat drug resistant pathogens. This study evaluated the antibacterial and antibiofilm efficacy of NFPPO, a novel nitrofuranyl pyranopyrimidinone derivative, against preformed 1-, 3-, and 5-day-old MRSA biofilms. Methods: NFPPO was synthesized via a tandem Knoevenagel-Michael cyclocondensation reaction. The minimum inhibitory concentration (MIC) of NFPPO was determined against four clinical MRSA isolates and the reference strain S. aureus ATCC 700699. Antibiofilm activity was assessed against preformed 1-, 3-, and 5-day-old MRSA biofilms using the crystal violet assay. Confocal laser scanning microscopy (CLSM) quantified structural and viability changes in preformed biofilms post-NFPPO treatment. Results: All tested MRSA isolates and S. aureus ATCC 700699 exhibited vancomycin resistance (classified as VRSA), whereas NFPPO showed potent antibacterial activity (MIC, 8–16 µg/mL). All isolates formed robust biofilms (OD625 ≥ 3.0). Crystal violet assays and CLSM demonstrated significant NFPPO antibiofilm activity, reducing biofilm biomass and viability. Conclusions: NFPPO exhibited superior antibiofilm efficacy compared to vancomycin in eradicating in vitro preformed 1-, 3-, and 5-day old MRSA biofilms. These findings position NFPPO as a promising candidate for further development to target biofilm-associated MRSA infections.