Essential oils (EOs) present limitations such as volatility, low water solubility, and instability, which restrict their direct application in pharmaceutical and cosmetic formulations. This study aimed to develop and characterize a nanoemulsion (NE) based on Melaleuca alternifolia EO, overcoming these challenges. The EO was extracted by hydrodistillation (yield: 3%) and analyzed by gas chromatography-mass spectrometry (GC-MS), identifying terpinen-4-ol (47.49%), γ-terpinene (17.89%), and α-terpinene (9.35%) as major components. The NE was prepared using ultrasound and Tween 80 as a surfactant, resulting in a monomodal distribution with a mean droplet size of 60 nm, confirmed by dynamic light scattering and the Tyndall effect. Stability assessments, including thermal and centrifugation tests, revealed a robust system, with optimal performance at 5-25 °C and controlled release behavior at 50 °C. The NE demonstrated potent antimicrobial activity, with minimum inhibitory concentrations (MIC) as low as 0.0078 µg mL-1. Although not directly compared to the crude EO, the results indicate preserved and possibly enhanced antimicrobial efficacy due to encapsulation. These findings suggest that the nanoemulsion is a promising platform for pharmacosmetic applications, enabling EO delivery at low concentrations while improving physicochemical stability and biological performance.
Oliveira et al. (Wed,) studied this question.