Nanoformulation of peppermint (Mentha piperita L.) and rosemary (Rosmarinus officinalis L.) Essential Oils: Antibacterial Effects

Essential oils are known for their natural antibacterial properties; however, their clinical and industrial applications are often limited by poor water solubility and low bioavailability. Nanoformulation techniques such as nanoemulsions, nanocomposites, nanocapsules, and liposomes have emerged as effective strategies to overcome these limitations, enhancing the stability, solubility, and antimicrobial activity of essential oils. This study investigates the antibacterial activity of peppermint ( Mentha piperita L.) and rosemary ( Rosmarinus officinalis L.) essential oils, delivered via various nanoformulations, against Staphylococcus epidermidis and Escherichia coli . Essential oils were extracted using a Clevenger apparatus and analyzed by GC-MS. Formulations were prepared, and particle sizes measured via electron microscopy. Antibacterial activity was also evaluated through antibiogram tests. All experiments were conducted in triplicate. The main components identified were methyl cyclohexanol (35.90%) in peppermint and camphor (23.22%) in rosemary essential oils. Particle sizes for peppermint nanoemulsions, nanocomposites, nanocapsules, and nanoliposomes were 3.34, 27.14, 19.25, and 19.01 nm, respectively; for rosemary, sizes were 2.69, 71.07, 35.02, and 25.38 nm. Both pure essential oils and their nanoformulations showed effective antimicrobial activity against Gram-positive and Gram-negative bacteria, with nanoforms exhibiting stronger effects. Gram-positive bacteria were more susceptible overall. Notably, nanoparticles and nanoliposomes had greater inhibitory effects than pure essential oils, and nanoemulsions demonstrated even higher antimicrobial activity than nanoliposomes. These results suggest that the essential oils of peppermint and rosemary, as well as their nanoformulations, may exhibit enhanced potency and could be effectively used as integrated agents against bacterial pathogens.