Encapsulation of Eucalyptus tereticornis extract in polylactic-co-glycolic acid nanoparticles: standardization, optimization and cell viability

Eucalyptus tereticornis extract is a promising drug for the treatment of type 2 diabetes mellitus and obesity, showing in vitro effects, such as increased glucose uptake and reduced lipid storage. However, its in vivo efficacy has been demonstrated only when administered intraperitoneally. Thus, this study focused on standardisation and optimisation of the preparation of polylactic-co-glycolic acid 50:50 nanoparticles (NPs). The size distribution of the NPs, polydispersity index, and zeta potential were evaluated to identify the NPs with the best encapsulation efficiency and loading capacity based on a first-order design using the response surface methodology. To evaluate cell viability of the NPs, in vitro viability assessments were performed using C2C12, 3T3-L1, HepG2, and J774A.1 cell lines and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The highest encapsulation efficiency and load capacity were 81.569 ± 1.798% and 1.885 ± 0.042%, respectively. These results confirmed the effective encapsulation of Eucalyptus tereticornis extract and the interactions between the components of the system. Finally, none of the evaluated concentrations negatively affected the cell line viability, confirming the reproducibility of the method with great pharmacological potential. In addition, this model can be used to develop nanoformulations that efficiently improve response.