Therapeutic potential of Melaleuca alternifolia essential oil in new drug delivery systems

Medicinal plants produce secondary metabolites with special biological activities, which may be used as new therapeutic alternatives. For instance, tea tree essential oil (TTO) was shown to exert antimicrobial, antifungal, anthelmintic, antiviral, anti-tumor and anti-inflammatory activities. Due to their thermal instability, active principles can be easily degraded by physicochemical processes; therefore, they must be protected to increase their time of action and improve their controlled release. The aim of this review is to report formulations making use of encapsulated TTO as the active ingredient. Micro and nanoencapsulated systems proved to be more thermostable than TTO and to exert better antimicrobial, antifungal, antiparasitic and larvicidal effects. Nanoencapsulation also reduced the oil toxicity. Emulsified and hybrid systems developed by various methods proved to be promising for the pharmaceutical industry, because they showed improved repellent, antibacterial, antifungal and anti-inflammatory activities. Liposomal formulations produced by hydration of lipid films exhibited constant rate of terpineol-4 release. In addition, their incorporation into biomaterials, such as sponges, nanofibers and films, showed great potential for treating infections. Mainly due to the advantages of their incorporation into new drug delivery systems over conventional formulations, there is interest in the development of systems containing TTO as a pharmaceutical ingredient of plant origin.