Plant Essential Oils Based Nanoemulsion Formulations and Its Antibacterial Effect on Some Pathogens

Antibiotic resistance is the most challenging problem of concern globally and this is invigorating the need of newer antimicrobial products with potential antimicrobial properties. Plant products, especially plant essential oils produce a large array of secondary metabolites as natural antimicrobials. Use of nanotechnology can add advantages to enhance the antibacterial properties of these essential oils. Present study is focused on development of nanoemulsions from plant essential oils and to study their antibacterial activities. Tea Tree Oil, Thyme Oil, Clove leaf and Cinnamon Essential Oils nanoemulsion was formulated using Tween 20 and Tween 80 respectively using probe ultrasonicator. All the formulated Nanoemulsions were then subjected to physicochemical characterization, stability studies and tested for antibacterial activities using Agar-well diffusion method. Stable nanoemulsion formulation with maximum antibacterial activity then subjected to droplet size measurements and polydispersibility index study. Increase in surfactant concentration resulted in reduction in droplet size when ultrasonication time was constant. Cinnamon oil nanoemulsion 20C4 & 80C4 with pdi index 0.573 and 0.382 and droplet size 272.3nm and 133.6 nm respectively demonstrated maximum antibacterial activity in Agar-well diffusion method against S.aureus, E.coli, and S.typhi. When both nanoemulsions were exposed to bacterial growth curve inhibition study. No potential rise in optical density of test pathogens were observed. The inhibition of bacterial growth may be due to killing action of cinnamon oil nanoemulsion formulations to initial bacterial inoculum added to nutrient broth. The study suggests that nanoemulsion formulations from plant essential oils can be used as natural antimicrobials in variety of products.