Lippia sidoides essential oil encapsulated in lipid nanosystem as an anti-Candida agent

Abstract

Essential oils (EOs) have high importance in various industrial sectors, due to their wide range of confirmed biological activity, such as antibacterial, antiviral, antifungal, antiparasitic, insecticide, analgesic, anti-inflammatory, and so on. The main components of essential oils belong to the classes of monoterpenes, diterpenes, and sesquiterpenes, compounds generally sensitive to oxygen, light, heat, and moisture. These substances may undergo irreversible changes when in contact with other materials or external agents, without adequate protection. In this way, micro and nanoencapsulation technologies arise as a viable and effective solution, since they furnish protection against instability problems, change product solubility, release of the bioactive substances, and might enhance the biological activity. In this study, essential oil (EO) of Lippia sidoides Cham. (L. sidoides) was loaded in lipid-based systems through emulsification by phase inversion. Gelucire® 50/13, stearic acid or Compritol® 888 ATO (solid lipids) and oleic acid or Labrasol® (liquid lipids) comprised the lipid phase, while Poloxamer® 188 or a combination of Tween® 80 and Span® 80 were the surfactants used. Twelve formulations were prepared, and their stability examined by visual inspection. Accelerated stability tests were carried out with the formulations containing Gelucire® 50/13, which appeared more stable. Formulations were characterised by the determination of the droplet size (214.4–423.2 nm), polydispersity index (around 0.3) and ζ-potential (−40.6 to −23.0). The antifungal activity against Candida albicans of the lipid base compositions loaded with L. sidoides EO, pure EO, and its major compound, thymol, was evaluated. The lipid-based formulations and the pure EO exhibited potent activity against this yeast, exhibiting Minimum Inhibitory Concentration (MIC) between 156 and 312 μg/mL. This study contributes to the development of an effective approach to enhance the essential oil stability and to form promising antimicrobial systems, which can be used in the most diverse sectors of the industry.