Simultaneous obtaining hydrophilic and hydrophobic compounds by ultrasonic synergistic extraction technology: The molecular mechanism of extraction and the multiple effects of macroporous adsorption resin

This study used ultrasonic synergistic extraction deep eutectic solvents (DES) technology to extract polysaccharides and flavonoids from A. membranaceus . Based on a comprehensive consideration of the yield of Astragalus polysaccharides (APS) and flavonoids , the best DES (choline chloride: oxalic acid = 1: 2) was selected from 16 different DES. The binding energy between the solvent and the target molecule was calculated using the density functional theory (DFT) in order to explore the molecular mechanism of DES for simultaneously extracting compounds with varying polarity. The results showed that the number of hydrogen bonds formed between the selected DES and glucose and calycosin-7-glucoside molecules was higher than that of the traditional solvents used for extracting these two substances. The adsorption capacity of 10 different types of macroporous adsorption resins for polysaccharides and flavonoids in the DES system was studied. Among them, HP-20 macroporous adsorption resin had better adsorption and desorption effects on flavonoids but almost no adsorption effect on polysaccharides. A pseudosecond-order kinetic equation is more suitable for fitting the adsorption characteristics of macroporous adsorption resins for flavonoids. At the same temperature, the Freundlich isotherm model is more suitable for fitting the adsorption behavior of HP-20 macroporous adsorption resin towards flavonoids. The adsorption thermodynamic parameters indicate that flavonoids are physically adsorbed on HP-20 macroporous adsorption resin in a spontaneous, endothermic, and entropy-increasing manner, and a high temperature is more suitable for the occurrence of adsorption behavior. In this study, polysaccharides and flavonoids were simultaneously extracted by green solvent , which provided enlightenment for the sustainable utilization of A. membranaceus resources.