Development, Stability and Antioxidant Activity of Microemulsion Containing Pequi (Caryocar brasiliense Camb.) Oil

The study of drug delivery systems can potentiate the action of ingredients carried by these systems and the evaluation of their quality parameters offers evidences of the compounds behavior in the formulations. This study aimed to obtain microemulsified formulations containing pequi (Caryocar brasiliense Camb.) oil and to determine its stability, plus its potential antioxidant activity. The pseudoternary phase diagrams were constructed using a mixture of the surfactants sorbitan oleate (Span 80), polysorbate 80 (Tween 80) and cosurfactant, 1-butanol, besides the triglycerides of capric/caprylic acid (Polymol 812) and distilled water. Pequi oil was incorporated in the proportion of 3% (w/w). The selected microemulsions were subjected to centrifugation, 14 days of heating - cooling cycles, and physicochemical analysis (pH, electrical conductivity and refractive index), and then evaluated. Five out of the initial seven formulations remained stable. Therefore, the formulations were subjected to accelerated conditions in triplicate for 90 days. Two microemulsions maintained adequate physical and chemical stability. The hydrodynamic diameter tests showed that two formulations had droplet size in nanometer scale. The rheological profile showed that both formulations presented newtonian behavior and linear viscosity. The analysis of the antioxidant activity showed that the formulations had significant activity and had this activity increased when the pequi oil was added. Concluding, the approved systems kept a remarkable stability and can be used as a modified vehicle to the oil extracted from pequi.