An investigation onto the potential antimicrobial, anticancer, and anti-inflammatory activities of a Origanum vulgare leaf oil self-nanoemulsifying system

This study aimed to formulate a self-nanoemulsion system using Origanum vulgare ( O. vulgare ) leaf oil and investigate the antibacterial, anticancer, and anti-inflammatory properties. The formulation of a nanoemulsion from O. vulgare leaf oil involved the self-nanoemulsifying technique, with Span 80 and Tween 80 acting as the emulsifying agents. The particle size, polydispersity index (PDI), antibacterial, cytotoxic, and anti-inflammatory properties were examined. The nanoemulsion formulation with a PDI of 0.216 and a particle size of 89.61 nm was identified as the optimal formulation. The formulation showed a zeta potential of -33.15 mV. The AFM values were in the range of 30–150 nm. The O. vulgare leaf oil self-nanoemulsion showed significant antimicrobial activity against MRSA, S. aureus , and P. vulgaris , with zone of inhibition diameters of 53, 52, and 48 mm, respectively, and a minimum inhibitory concentration (MIC) against MRSA, S. aureus , P. vulgaris , E. coli , and K. pneumonia of 0.19 µg/mL. The IC₅₀ values of the optimized nanoemulsion were 7.58 µg/mL for HeLa, 7.24 µg/mL for Caco-2, 8.23 µg/mL for MCF-7, 10.02 µg/mL for Hep-G2, 9.6 µg/mL for B16-F7, and 12.02 for LX-2 compared with 12.08, 12.58, 14.12, 18.1, 14.85, and 14.79 µg/mL, respectively, for the crude essential oil. Importantly, the optimized nanoemulsion exhibited 2846.33 µg/mL against the healthy HEK-293 cell line, indicating a degree of preferential cytotoxicity toward the tested cancer cells. These findings suggest that nanoemulsification may enhance the anticancer activity of the essential oil while potentially improving its selectivity. Regarding its anti-inflammatory effects, O. vulgare leaf oil demonstrated activity against both COX-1 and COX-2, with greater selectivity for COX-2. Accordingly, an optimized O. vulgare leaf-oil self-nanoemulsifying system was successfully developed, and the results suggest the possibility of using the self-nanoemulsification process to enhance the functional properties of the chemically characterized O. vulgare leaf oil.