Molecular modeling study of micro and nanocurcumin with in vitro and in vivo antibacterial validation

Repurposing natural compounds as inhibitory targets to combat bacterial virulence is an important potential strategy to overcome resistance to traditional antibiotics, in the present study, the antibacterial activity of micro-curcumin and nano-sized curcumin was investigated against four predominant bacterial pathogens, namely, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis. Curcumin bactericidal susceptibility could be summarized as the order, P. aeruginosa > B. subtilis > S. aureus > E. coli. Molecular docking analysis was conducted to confirm the impact of curcumin on the most vital and positively identified quorum-sensing pathway signaling proteins SecA-SecY, LsrR, PqsR (MvfR), AgrA which act as key players in the bacterial communication systems. The in silico physicochemical properties revealed that curcumin as a nutraceutical can be classified as a drug-like compound. An in vivo infected wound model was employed in four groups of albino rats. Topical application of nano-curcumin lotion showed a marked reduction in wound area (98.8%) as well as nearly 100% reduction in total bacterial viable count compared to the control group, on the fifteenth day post-treatment post-injury. The obtained data suggested that curcumin nanoparticles exhibited superior antibacterial activity and may possess clinical utility as a novel topical antimicrobial and wound healing agent.