Abstract The objective of this study was to evaluate the influence of vitamin C (VC) on the stability of stored liposomes under different climatic conditions. Liposomal formulations containing 1 mg/mL of VC (LIP-VC) and blank formulations (LIP-B) were prepared by the reverse-phase evaporation method. After preparation, they were characterized according to their refractive index, average vesicle diameter, polydispersity index (PDI), zeta potential, pH, content, encapsulation efficiency (EE%), morphology, stability and antioxidant activity. For stability, LIP-VC and LIP-B were stored in different climatic conditions (4 °C, 25 °C and 40 °C) for 30 days. The LIP-VC presented 1.3365 refractive index, 161 nm of mean diameter, 0.231 PDI, -7.3 mV zeta potential, 3.2 pH, 19.4% EE%, spherical morphology, 1 mg/mL of VC content, and antioxidant activity of 12 and 11.4 μmol of TE/mL for the radical DPPH and ABTS+, respectively. During stability, the LIP-B stored in 40 °C showed an instability in the parameters: PDI, vesicle size and zeta potential after 15 days, while the LIP-VC remained stable in its size and PDI for 30 days. After that, it is shown that VC can be used as an antioxidant and stabilizer in liposomes to increase the stability and shelf-life of vesicles.

A reliable method using LC-UV to assay mometasone furoate (MF) in creams or nasal sprays using the same chromatographic conditions was set up. Methanol:water 80:20 (v/v) (1.0 mL min-1) was used as mobile phase. MF was detected at 248 nm and analyzed in a concentration range from 1.0 to 20.0 µg mL-1. The method provided acceptable theoretical plates, peak simmetry, peak tailing factor and peak resolution a short run (5 min). The method showed specificity, good linearity (r = 0.9999) and the quantification limit was 0.379 µg mL-1. Furthermore, the method was precise (RSD < 2.0%), accurate (recovery > 97%) and robust.

The goal of this study was to evaluate the feasibility of preparing nanocapsules and nanoemulsions using tea tree oil as oily phase aiming to protect its volatilization. The nanostructures presented nanometric mean size (160-220 nm) with a polydispersity index below 0.25 and negative zeta potential. The pH values were 6.43 ± 0.37 and 5.98 ± 0.00 for nanoemulsions and nanocapsules, respectively. The oil content after preparation was 96%. The inclusion of tea tree oil in nanocapsules showed higher protection against volatilization. The analysis of mean size and polydispersity index of formulations presented no significant alteration during the storage time.