Subhashini Brahadeeswaran, Ramasamy Tamizhselvi
Plant-derived exosome-like nanoparticles (P-DENs) have emerged as promising bio-nanocarriers with antimicrobial potential. In this study, we isolated and characterized exosome-like nanovesicles from Rosa damascena and evaluated their antibacterial efficacy against Salmonella enterica, a significant foodborne pathogen. Rosa damascena-derived exosomes-like nanovesicles (R-DENs) exhibited 8.9 × 109 particles/mL in nanoparticle tracking analysis. Growth assays revealed significant inhibition of bacterial proliferation (63.52%). Propidium iodide (PI) staining in flow cytometry demonstrated concentration-dependent bacterial cell death (65.78%), while scanning electron microscopy (SEM) visualized distinct ultrastructural damage to the bacterial envelope, confirming membrane disruption as a primary antibacterial mechanism. Consistent with these effects, R-DENs markedly reduced biofilm formation (69.88%) and suppressed exopolysaccharide (EPS) production (69.10%). Elevated intracellular reactive oxygen species (ROS) levels (up to 65.37%) further indicated oxidative stress as a major antibacterial contributor. Moreover, R-DENs treatment impaired bacterial adhesion (77.88%) and invasion (67.37%) in L929 fibroblasts, correlating with attenuation of pathogenicity. Gene expression analysis confirmed significant downregulation of biofilm- and virulence-associated genes (fimA, csgD, bcsA, rsmA, and rpoS), linking the phenotypic changes to molecular interference with pathogenic pathways. Collectively, these findings demonstrate that R-DENs exert multifaceted antibacterial activity through membrane disruption, biofilm and EPS inhibition, ROS generation, and suppression of virulence traits, underscoring their potential as natural, biocompatible nanotherapeutics against drug-resistant bacterial infections.