Evaluation of supercritical carbon dioxide extraction to obtain bioactive compounds from vernonia amygdalina delile leaves

Abstract

Literature reports have shown that supercritical extraction is a promising method to obtain bioactive compounds used to develop drugs based on natural products. This work investigated the yield, antioxidant activity, and phytochemical constituents of the extracts obtained from Vernonia amygdalina Delile leaves with supercritical CO2. The supercritical extraction was examined at temperatures of 40, 50 and 60 °C and at pressures of 200 and 250 bar. The supercritical fluid extraction (SFE) method was compared with the classical Soxhlet using different solvents at atmospheric pressure. The overall yield obtained using SFE varied from 0.69 to 1.24%. The extraction conditions which favored the highest yield were 60 °C and 250 bar. The overall SFE curves were fitted using three mathematical models. All of them were able to describe satisfactorily the extraction kinetics. Spline model presented the best fit to experimental data and was able to characterize constant and decreasing extraction rate periods. Extracts were characterized by gas chromatography coupled with mass spectrometry technique and some major components were identified. The antioxidant activity tests showed that the SFE extracts had low antioxidant activity exhibiting the estimated concentration of extract required to reduce 50% of the stable free radical DPPH (EC50) values to be between 622.62 and 937.88 µg mL-1.