Géis à base de nanoemulsões de curcuminoides para aplicação cutânea

Abstract

The skin is the largest organ in the human body and it is susceptible to physical injury and wounds. This study aims to develop a product which would help in the healing process of skin wounds and burns. This product is based on curcuminoids nanoparticles, which can be used for wound and burns healing and other biomedical applications with expressive antioxidant and antibacterial activity. For this, initially the curcuminoids were extracted from the saffron rhizomes and characterized by 13C and 1H Nuclear Magnetic Resonance, High Efficiency Liquid Chromatography (HPLC) and Infrared Spectroscopy, later the development process consists in the preparation of curcuminoids nanoemulsions, varying the amount of organic phase, caprylic/capric acid triglyceride (TACC) derived from coconut oil and the percentage of surfactant F127, which were submitted to particle size and zeta potential analysis. Two formulations were selected, which presented smaller particle sizes, varying from 180 to 210 nm, with values of polydispersity index (PDI) between 0.1 and 0.3, which shows a moderately polydispersed distribution and zeta potential varying from -26 to -29 mV. Afterwards, these nanoemulsions were submitted to preliminary studies of stability at a temperature of 26 ± 2 ºC and 45 ± 2 ºC for 90 days and analyzed again by particle size, PDI, zeta potential, hydrogen potential (pH) and curcuminoids quantification. The nanoemulsions behaved as expected with pH reductions between 4.0 and 5.1 in the ideal limit for skin application and stability of curcuminoids. The quantification of the systems at room temperature did not show significant changes, keeping the percentage of degradation less than 10%, indicating an estimated validation time of 12 months. Tests of sequestration of the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical and ferrous ion chelation were realized and proved that, even after the encapsulation, the system showed high antioxidant power. At a concentration of 10 μg/mL eliminated 86.4% of the DPPH free radical and presented a chelating ability of 64.3%, values that exceed the positive controls of the analyzes. TEM and AFM images of nanoemulsions revealed spherical shape of the formulations. Emulsions presented 100% of encapsulation efficiency (EE) and in the in vitro release study showed up to 14.2% release of curcuminoids in 24 hours, with controlled release profile. The study of release kinetics revealed a zero order reaction, as desired. Nanoemulsions were used as the basis for the production of termoresponsive gels of F127. Rheological studies were performed to delineate the profile of the gels produced and the results showed that the addition of the nanoemulsions reduced the temperature of sol-gel transition when compared to pure gels of F127. In addition, the value of the elastic mode (G') was maintained between 1 and 3 kPa, characterizing the gels as fluids.