Supercritical fluid extraction of phenolics from Anisophyllea disticha (Jack) Baill. and evaluation of their antioxidant activities

Abstract

Anisophyllea disticha (Jack) Baill. (A. disticha) is a species of the Anisophylleaceae family that has undergone the least investigation despite being widely used in folk medicine to cure a wide range of illnesses. The purpose of this study is to examine the impact of various factors on the supercritical fluid extraction of A. disticha in order to maximise recovery of total phenolic content, antioxidant activity, and polyphenol identification. The total phenolic content (TPC) and antioxidant activities of A. disticha were determined using the supercritical fluid extraction (SFE) method and compared with Soxhlet. Box-Behnken design of response surface methodology was performed to examine the effect of independent variables of SFE such as temperature, pressure, and concentration of ethanol as co-solvent on TPC and antioxidant activities of A. disticha stem extracts. At combined effects of different temperatures, pressure, and co-solvent, the total SFE yield were ranged between 0.65 and 4.14%, which was about half of the Soxhlet extract of 8.75±1.54%. The highest concentration (µg/g) of gallic acid (118.83±1.17), p-coumaric (61.60±0.33), ferulic acid (57.93±1.15), and quercetin (24.16±0.41) were obtained at a temperature of 50 ˚C, the pressure of 25 MPa and co-solvent of 20%, while lowest concentration was found 70 ˚C, 30 MPa, and 20% ethanol. SFE extracts possessed remarkable TPC and concentration of phenolic compounds, indicating superior recovery of compounds. SFE showed more than two-fold higher ferric-reducing antioxidant power compared to Soxhlet with values of 585.32±17.01 mg Fe (II)/g extract and 203.63±16.03 mg Fe (II)/g extract, respectively. SFE demonstrated a potential alternative to the classical solvent extraction methods.