Supercritical Fluid Extraction of Polyphenols from Vietnamese Callisia fragrans Leaves and Antioxidant Activity of the Extract

Abstract

Vietnamese Callisia fragrans (C. fragrans) has been considered as a valuable traditional plant with various medicinal properties. In this study, polyphenols were extracted from Vietnamese C. fragrans leaves by supercritical carbon dioxide (SC-CO2) extraction method using ethanol as a cosolvent. The investigation of four factors influencing the total polyphenol content (TPC) and antioxidant activity of the extracts obtained from each single-factor experiment was conducted including ethanol concentration, CO2 flow rate, extraction temperature, and pressure. Besides, the extraction efficiency of the SC-CO2 method under the best extraction conditions, namely ethanol concentration of 14%, CO2 flow rate of 20 g/min, extraction temperature of 45°C, and pressure of 200 bar was compared to that of the Soxhlet extraction (SE) method in terms of the TPC and antioxidant activity of the extracts. The results showed that using SC-CO2 method, the TPC and the half-maximal inhibitory concentration value obtained were of 87.42 ± 1.33 mg/g and 243.83 ± 5.30 μM TE/g, respectively, with much less time and solvent amount required while that obtained using SE method were of 85.34 ± 4.27 mg/g and 236.33 ± 7.66 μM TE/g, respectively. This indicated that SC-CO2 would be suitable for the industrial production of polyphenols with high antioxidant activity of the extracts obtained due to the restrictions of using the SE method and advantages of applying SC-CO2 method. Therefore, SC-CO2 method could be regarded as a potentially upcoming extraction technique which might be employed to replace the conventional SE method.