Anti-Biofilm Potential of Nanonized Eugenol against Pseudomonas aeruginosa

This study dealt with nanonization of eugenol, a major phytochemical present in basil leaf, which has pharmacological potential as an anti-bacterial agent. Eugenol nanoparticle (ENP) was synthesized by simple ultrasonic cavitation method through emulsification of hydrophobic eugenol into hydrophilic gelatin. Thus, the nanonization process made the water-insoluble eugenol to water-soluble nano-eugenol, making the nano-form bioavailable. The average size of the ENPs was 20-30 nm. Entrapment efficiency of eugenol within gelatin cap was about 80% of the eugenol, that was used as precursor in the nanonization reaction. In vitro release of eugenol from gelatin cap was slow and sustained over a period of five days. The ENP had higher anti-biofilm potency than eugenol for both formation and eradication of biofilm, formed by clinically relevant pathogen Pseudomonas aeruginosa. Minimal biofilm inhibitory concentration and minimal biofilm eradication concentration of ENPs were 2.0 and 4.0 mM respectively. In addition, the measurement of P. aeruginosa biofilm biomass, biofilm pellicle formation, biofilm thickness, amount of biofilm-forming extra-polymeric substance, cell surface hydrophobicity, cell swarming and twitching efficiencies, cellular morphology and biofilm formation in catheter demonstrated that the anti-biofilm efficacy of nano-eugenol was 30-40% higher than that of bulk eugenol. Thus, ENP can be used as a potential drug against pneumonia, a chronic infection in lung caused by P. aeruginosa, which is difficult to treat with antibiotics, due to natural intrinsic resistance of biofilm-formed cells to most antibiotics. The overall actions of ENP have been presented in the figure 1. Highlights Nano-formulation of eugenol, an important phytochemical, by ultrasonic cavitation method, which was simple, time-saving, low-cost and eco-friendly. Nanonization made water-insoluble eugenol into water-soluble form with enhanced therapeutic efficacy. The eugenol nanoparticle (ENP) could inhibit formation of biofilm as well as facilitate eradication of pre-formed biofilm of P. aeruginosa. Biofilm formation was found to be prevented significantly on ENP-coated catheter. Nano-eugenol may be used as a potential drug against bacterial diseases, caused by pseudomonal biofilm, which are difficult to treat by antibiotics. Nano-formulated eugenol may also be used as an effective anti-fouling agent for biomedical devices like contact lens, pace-maker, materials for organ transplantation etc. to prevent bacterial colonization.