Priscilla Maciel Quatrin

Evaluation of Stability and In Vitro Security of Nanoemulsions Containing Eucalyptus globulus Oil

Essential oil of Eucalyptus globulus presents several pharmacological properties. However, their therapeutic efficacy may be affected by limitations due to several conditions, rendering it difficult to obtain stable and effective pharmaceutical formulations. The use of nanotechnology is an alternative to improve their characteristics aiming to ensure their stability and effectiveness. Furthermore, studies about the possible toxic effects of nanostructures are necessary to evaluate safety when the formulation comes into contact with human cells. Hence, in this paper, we evaluate for the first time the stability and in vitro cytogenotoxicity of nanoemulsions containing Eucalyptus globulus in peripheral blood mononuclear cells. As a result, the stability study found that the best condition for storage up to 90 days was refrigeration (4°C); it was the condition that best preserved the nanometric features. The content of the major compounds of oil was maintained after nanoencapsulation and preserved over time. In tests to evaluate the safety of this formulation, we can conclude that, at a low concentration (approximately 0.1%), Eucalyptus globulus nanoemulsion did not cause toxicity in peripheral blood mononuclear cells and also showed a protective effect in cells against possible damage when compared to oil in free form.

Nanoemulsions containing Cymbopogon flexuosus essential oil: Development, characterization, stability study and evaluation of antimicrobial and antibiofilm activities

The increase of microbial resistance generates the search for new substances with antimicrobial potential. The essential oil of Cymbopogon flexuosus (Lemongrass) stands out in the literature for its antimicrobial, insecticide and antioxidant properties, but it has high volatilization and low stability, and the nanoencapsulation of this oil could be an alternative to overcome these limitations. Thus, the objective of this study was to develop, for the first time, nanoemulsions containing the essential oil of C. flexuosus, through a method that does not use organic solvent and with temperature control to avoid the volatilization of the oil, characterize and evaluate of stability and the antimicrobial and antibiofilm activities of these nanoemulsions. Nanoemulsions presented adequate physicochemical characteristics (average size less than 200 nm, polydispersity index less than 0.3, negative zeta potential and acid pH) which were maintained during 90 days of storage, and the nanoencapsulation of the C. flexuosus oil enhanced its therapeutic efficacy against the microorganisms evaluated in this study compared to the free oil. These results are very promising because among the microorganisms that the nanoemulsion containing C. flexuosus was able to inhibit the formation of biofilm are the bacteria Pseudomonas aeruginosa and Staphylococcus aureus, which were recently listed by the World Health Organization as priority pathogens for development of new antibiotics.