Pressurized liquid and ultrasound-assisted extraction of α-bisabolol from candela (Eremanthus erythropappus) wood

Alpha-Bisabolol is an optically active sesquiterpene applied in various commercial products and obtained at high concentration in essential oil extracted from candeia (Eremanthus erythropappus (DC.) Macleish) wood. In this study, the non-conventional pressurized liquid extraction (PLE) and ultrasound-assisted extraction (UAE) methods were employed to evaluate candeia oil quality in terms of yield and a-bisabolol content in comparison with Soxhlet and hydrodistillation techniques. The extractions with n-hexane, ethanol, and ethyl acetate (Soxhlet and PLE) showed the affinity of the compounds for polar solvents and the positive effect of temperature on the yield. However, the highest purity in terms of alpha-bisabolol was obtained with the apolar solvent n-hexane (up to 64.23%). Besides the alpha-bisabolol, alpha-bisabolol B, and isovaleric acid were found in the composition of the essential oil extracted by hydrodistillation, while the oil extracted with n-hexane also presented the sesquiterpenes eremanthin and costunolide. The UAE was performed using a Box-Behnken experimental design to evaluate the effect of the variables temperature, volume of n-hexane to wood mass ratio, and amplitude percentage on the yield of oil. In 7 min of extraction, up to 83% of the yield obtained in the conventional technique in Soxhlet (360 min) were obtained, with a solvent volume 2.5 times smaller, as well as a high yield of alpha-bisabolol (up to 8.90 g(alpha-bisabolol) kg(wood)(-1)).