Effects of ultrasonic-enzymatic-assisted ethanol precipitation method on the physicochemical characteristics, antioxidant and hypoglycemic activities of Tremella fuciformis polysaccharides

Abstract

This investigation involved the extraction of a novel polysaccharide from the spore fermentation broth of Tremella fuciformis using a method that combined ultrasonic and enzymatic assistance with ethanol precipitation. It was then compared with enzymatic and ultrasonic extraction methods. The objective of this research is to offer a reference point for expanding the application of ultrasonic-assisted enzymatic extraction technology in T. fuciformis polysaccharides (TFPs). Based on single-factor experiments, Box-Behnken was used to optimize the extraction conditions of TFPs by ultrasonic-enzymatic-assisted ethanol precipitation extraction. The results revealed an optimal combination of enzymes, with a cellulase-to-papain ratio of 2:1, an enzyme addition of 4000U/100 mL, an enzymolysis temperature of 49 °C, ultrasonicpower at 3 W/mL and an ultrasonictime of 20 min. The extraction rate of TFPs and α- amylase inhibition rates were 23.94 % and 61.44 %, respectively. Comparing the physicochemical properties, structural characterization and in vitro activity of TFPs extracted through different methods, the results showed that ultrasonic treatment significantly influences the apparent morphology of polysaccharide and could enhance its in vitro biological activity. However, different extraction techniques exhibit insubstantial impact on the chemical composition, glycosidic bonds or glycosidic ring configurations within the polysaccharides. Among them, ultrasonic-enzymatic-assisted ethanol precipitation extraction of polysaccharide has the highest extraction rate and the lowest viscosity. It has significant effects on ABTS⁺ scavenging activity, α- amylase inhibition rate and glucose dialysis retardation index, polysaccharide treated with ultrasonic-enzymatic showed the best performance. These findings suggest that ultrasonic-enzymatic-assisted ethanol precipitation extraction can enhance the activities of TFPs, thereby providing a valuable insight for their future development and application.

Keywords: Antioxidant activity; Hypoglycemic activity; Structural characterization; Tremella fuciformis polysaccharides; Ultrasonic-enzymatic-assisted ethanol precipitation extraction.