Enhanced antimicrobial and antibiofilm effects of Baccaurea ramiflora Lour. fruit extract combined with FMSP-nanoparticles against multidrug-resistant bacteria: an in vitro and in silico analysis

Abstract

The increasing prevalence of antimicrobial resistance (AMR) and biofilm-associated infections poses significant challenges to public health. This study investigated the antibacterial and antibiofilm potential of ethanol extracts of Baccaurea ramiflora Lour. (B. ramiflora) peel (BRP) and seed (BRS) extract, combined with fluorescent magnetic submicronic polymer nanoparticles (FMSP-NPs), against Gram-negative multidrug-resistant Pseudomonas aeruginosa (MDRPA) and Gram-positive methicillin-resistant Staphylococcus aureus (MRSA). FMSP-NPs were synthesized via hetero-coagulation and characterized by Scanning Electron Microscopes (SEM) and Transmission Electron Microscopes (TEM). Antibacterial activity such as Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and morphology was evaluated using microbroth dilution and biofilm inhibition by crystal violet assay method. Molecular docking was performed to predict the binding poses of 18 selected phytoconstituents from BRP and BRS against Staphylococcus aureus (S. aureus) Gyrase B and Sortase A, targeting antibacterial and antibiofilm activity. FMSP-NPs were spherical, measuring 100–300 nm in diameter. Among all formulations, FMSP-BRP showed the highest antibacterial activity, with MIC/MBC values of 0.25/0.5 mg/mL against Pseudomonas aeruginosa (P. aeruginosa) and 2/4 mg/mL against S. aureus, causing pronounced cellular damage observed by SEM. FMSP-BRP exhibited the highest biofilm inhibition, with 65.1% against P. aeruginosa and 59.2% against S. aureus, compared to FMSP-BRS (49.6%, 44.7%) and FMSP-NPs (39.7%, 38.4%). It markedly reduced biofilm integrity, bacterial colonization, and Extracellular polymeric substances (EPS) matrix formation. Molecular docking identified proanthocyanidin as the most active phytoconstituent, demonstrating the highest binding affinity toward S. aureus Gyrase B and Sortase A. These findings highlight FMSP-BRP nanocomposites as promising candidates for combating drug-resistant bacterial infections. These findings support the traditional use of B. ramiflora against infectious diseases and underscore the potential of nanotechnology-based natural extracts in combating AMR.