Microemulsions are thermodynamically stable isotropic systems comprising of oil, surfactant and water. Cinnamon oil (Cinnamomum zeylanicum) microemulsion was formulated using non-ionic surfactant Tween 20 and water. With oil to surfactant (v/v) ratio of 1:4, cinnamon oil microemulsion (CMF4) was formulated having droplet diameter of 5.79 and kinetically stable for 240 days. TEM images confirmed the spherical morphology of emulsion droplets. Surfactant concentration demonstrated a negative correlation with droplet diameter and turbidity but positive correlation with stability and viscosity. Formulated microemulsion (CMF4) was evaluated for bactericidal activity against Staphylococcus aureus by dose and time dependent killing experiment. SEM analysis suggested that microemulsion treatment resulted in alteration of permeability and surface features of bacterial cell membrane which lead to lysis and cell death. CMF4 showed no erythema for skin irritation test in wistar rats and triggered wound-healing process in wistar rats. Control group without any treatment, cinnamon oil only and neomycin treated group healed in 20, 16 and 16 days, whereas cinnamon oil formulation (CMF4) treated group was healed in 14 days.
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