Preparation and characterization of lemongrass oil nanoemulsion: Antimicrobial, antibiofilm, antioxidant, and anticancer activities

Although citrus essential oils, including lemongrass essential oil, have antibacterial, anti-biofilm, and antioxidant properties, their biological instability and poor water solubility render them unsuitable for industrial usage. Thus, this study aimed to prepare both lemongrass essential oil emulsion (LEO-E) and lemongrass essential oil nanoemulsion (LEO-NE), and evaluate their different bioactivities. Characterization by gas chromatography-mass spectroscopy (GC-MS) and evaluation of antimicrobial, antibiofilm, antioxidant, and anticancer activities were carried out. GC-MS results illustrated that D-limonene compound is the dominant among other compounds in LEO. According to transmission electron microscopy and dynamic light scattering, LEO-NE appeared as spherical-shaped droplets with a constant size spanning from 29.1 to 37.4 nm with a polydispersity index value of 0.163. Antimicrobial results showed that LEO-NE exhibited promising antimicrobial activity against <i>Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans</i>, and <i>Austromerope brasiliensis</i> with inhibition zones of 25.33 ± 1.1, 26.5 ± 0.5, 22 ± 1, 24.33 ± 0.5, 28.6 ± 1, and 27.97 ± 0.9 mm, respectively. Moreover, LEO-NE showed considerable antiـbiofilm efficacy toward <i>S. aureus</i> and <i>P. aeruginosa</i> with inhibition percentages at 1/2 of MIC of 98.92 and 92.62%, respectively. Furthermore, LEO-NE exhibited antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl method with 88.5% at 100 µg/mL concentration. In addition, LEO-NE displayed potential anticancer activity toward the human prostate cancer cell line (PC3) and human liver cancer cell line (Hep-G2), where IC₅₀ values were 170.09 and 105.06%, respectively. In conclusion, the prepared LEO-NE in the current study had antimicrobial, antibiofilm, antioxidant, and anticancer activities, which can be used in the medical and pharmaceutical fields.