Development of nanostructured lipid carrier containing tea tree oil: Physicochemical properties and stability

Context: Tea tree oil (TTO) is an essential oil derived from Melaleuca alternifolia, with high antimicrobial and antifungal potential. Unfortunately, its topical antifungal efficacy is limited because it is volatile, thermolabile and easily oxidized. A formulation has been developed to overcome this problem by encapsulating TTO in a nanostructured lipid carrier (NLC). Aims: To determine the effect of the liquid to solid lipid ratio on the physicochemical properties and the stability of TTO-loaded NLC. Methods: Five formula of TTO-loaded NLCs were produced by high shear homogenization method and characterized according to their particle size, size distribution, polydispersity, zeta potential, thermal characteristics, X-ray diffraction, and terpinen-4-ol concentration. In addition, a stability study was conducted by observing its physical and chemical characteristics during storage in the refrigerator (4 ± 2 C) and at room temperature (27 ± 2 C) for six months. Results: The resulting TTO-loaded NLC had an average droplet size under 400 nm. The particle size increases with increasing amount of liquid lipid in the formula. There were insignificant changes in organoleptic properties, polydispersity index, zeta potential and terpinene-4-ol concentration during stability study for six months. However, the particle size slightly increased during the six months of storage. Furthermore, the NLC 3, which formulated with a 25:95 ratio liquid to solid lipid, was be chosen as the best formula, since it demonstrated the best physicochemical characteristic and stability. Conclusions: TTO-loaded NLC with good physicochemical characteristics and stability has been successfully developed. In addition, NLC 3 is considered as the best NLC formula, which exhibits characteristics and stability that meet the requirements.