Desenvolvimento de nanoemulsões contendo esqualano para incorporação de compostos bioativos

Abstract

In the context of skin aging triggered by oxidative stress, vitamins C and E are widely recognized for their antioxidant action and synergistic effect. However, their application is limited by challenges such as the low bioavailability of vitamin E and the solubility incompatibility between the two. Nanotechnology emerges as a promising alternative to enhance the stability, bioavailability, and skin permeation of these compounds. In this scenario, the choice of the active carrier plays a fundamental role, as its properties directly influence the release and delivery of the compounds to the target site.Squalane stands out as a promising component in the development of nanoemulsions due to its biocompatibility and ability to carry lipophilic actives. In this context, this study developed and characterized soybean lecithin-based nanoemulsions containing different proportions of coconut oil and squalane for the delivery of vitamins C and E, targeting cosmetic applications. The formulations showed a hydrodynamic diameter below 200 nm, a polydispersity index (PDI) lower than 30%, and a high Zeta potential, demonstrating stability for 90 days. Scanning electron microscopy (SEM) revealed morphological variations according to the oil phase and presence of the vitamins, while thermogravimetric analysis (TGA) indicated that the carrier oils increased the thermal stability of the actives. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of the vitamins in the nanoemulsions, with high encapsulation efficiency (vitamin E: 99.66 ± 0.01 to 99.48 ± 0.02%; vitamin C: 31.04 ± 3.17 to 84.19 ± 8.93%), in agreement with the literature. The release of vitamin E fit the Higuchi (1961) and Korsmeyer-Peppas (1983) models. Skin permeation assays indicated that the V.E 2:1 nanoemulsion exhibited greater skin retention (2000.0 ± 12.4 µg cm⁻²), while the V.C+E 1:2 formulation showed the highest permeation flux (77.2 ± 1.0 μg cm⁻² h⁻¹) and permeability coefficient (3.9 × 10⁻³ ± 0.9 cm h⁻¹). Thermodynamic analysis revealed system stability, low activation energies (13.03 to 26.06 kJ mol⁻¹), and constant entropy across all samples (−0.20 J K⁻¹ mol⁻¹), in addition to the Gibbs free energy of diffusion ranging from 54 to 62 kJ mol⁻¹. Dehydration of the system components may have influenced the variations observed in diameter and PDI. Acetylcholinesterase (AChE) inhibition was evaluated, showing that isolated vitamin C did not inhibit the enzyme, whereas its incorporation into the nanoemulsion system resulted in inhibition, suggesting a synergistic effect. The results highlight the potential of the developed nanoemulsions for dermocosmetic and therapeutic applications, expanding the possibilities for the use of vitamins C and E, as well as emphasizing the importance of selecting an appropriate carrier system.