Chemical Characterization, Cytotoxic Activity, and Antimicrobial Potential of Nanoemulsions Based on Cymbopogon...

The essential oils (EOs) of Cymbopogon citratus (DC.) Stapf are globally recognized for their antimicrobial properties. However, their therapeutic potential is limited by their low solubility and potency. This study aimed to investigate the chemical constituents, cytotoxic activity, and antimicrobial potential of nanoemulsions based on C. citratus EOs. Thirteen primary components were analyzed using gas chromatography-mass spectrometry. The major components were geraniol acetate (50.81%), citral (16.97%), β-citral (12.95%), and geranial (9.45%). Nanoemulsions containing three different concentrations (1%, 5%, and 10%) of EOs were evaluated regarding the droplet size, polydispersity index, pH, conductivity, and viscosity. The results demonstrated that nanoemulsions with spherical shapes and droplet sizes less than 143 nm were successfully formed at all tested concentrations, with average sizes of 143, 132, and 82 nm, respectively. Furthermore, all formulations were physically stable, even after undergoing stability testing. The EO of C. citratus exhibited potent antibacterial activity against a broad range of foodborne pathogens, including both Gram-positive and Gram-negative bacteria, with Salmonella Paratyphi A being the most susceptible strain. The aforementioned nanoemulsions were more effective against methicillin-resistant Staphylococcus aureus and Bacillus cereus. The nanoemulsions did not induce any significant cytotoxicity within the concentration range of 0.05-2 μg/mL in 24 h (p > 0.05). The cell viability consistently remained above 85%, even at the highest concentration tested. These findings suggested the strong potential of C. citratus EOs and their nanoemulsion forms as natural antimicrobial agents for applications in the food and pharmaceutical industries.