Formation, characterization, and biological activity of lipid systems loaded by essential oil

• Ano de defesa: 2022
• Autor(a) principal: Baldim, Iara
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Carreadores lipídicos nanoestruturados; Encapsulação; Encapsulation; Essential oils; Liposomes; Lipossomas; Lippia sidoides; Microrganismos multirresistentes; Multidrug-resistant microorganisms; NLC; Óleos essenciais
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/60/60137/tde-31052022-084754/

Essential oils (EOs) have aroused great interest in recent years, mainly due to their wide range of biological activities, such as antifungal, antibacterial, insecticide, antiviral, antioxidant, among others. Its use as an active ingredient brings countless benefits, and maybe the main advantage is related to its ability to fight the resistance often presented by microorganisms against antibiotics and antifungals available on the market. However, the high volatility and sensitivity of these compounds restrict their use, limiting the incorporation into more elaborate products. Microencapsulation and nanoencapsulation of EOs emerge as viable and efficient strategies to protect and modulate the release of their bioactive compounds, promoting increased physical-chemical stability, protection against environmental factors, reduced volatility, increased solubility, bioavailability and biological activity, reduction of toxicity, among other benefits. Lipid systems are an especially promising strategy for EO incorporation, as they are biocompatible, present high loading capacity, low cost, low toxicity, and can encapsulate both lipophilic and hydrophilic substances. Among these systems, the liposomes are biocompatible, biodegradable vesicles with a potential pharmaceutical application; and nanostructured lipid carriers (NLC) are nanoparticles able to carry chemically different molecules, providing an adjustable release profile, which can be produced on a large scale, without the need for organic solvents. The influence of the encapsulation system, lipid components, type of emulsifier, and other excipients must be evaluated to optimize system stability, retention of bioactive compounds, and improve their biological activity. This thesis aimed to investigate the technological routes involved in obtaining micro or nanostructured lipid systems to stabilize and modulate the release of rosemary-pepper (Lippia sidoides) and clove (Syzygium aromaticum) essential oils were investigated, emphasizing the preparation processes, physicochemical properties, stability, and biological activity against multidrugresistant microorganisms of clinical importance. The main formulation and process variables were analyzed, defining optimal processing conditions for liposome-based systems encapsulating essential oil complexed in β-cyclodextrin and for NLCs. Assays of antifungal activity against different microorganisms were performed for NLCs, which proved to be efficient in combating the multidrug-resistant fungus Candida auris, which has spread globally, mainly in hospital environments, with very limited or non-existent treatment options.