Effects of Different Deproteinization Methods on the Antioxidant Activity of Polysaccharides from Flos Sophorae Immaturus Obtained by Ultrasonic Microwave Synergistic Extraction

Abstract

Flos Sophorae Immaturus (FSI) serves as one of the Chinese medicinal herbs of homologous provenance, whose polysaccharides constitute part of the active compounds that exert their pharmacological properties. Single-factor and response surface methodology were employed to investigate optimal extraction conditions for the ultrasonic-microwave synergistic extraction (UMSE) of polysaccharides from FSI (PFSI), which were deproteinized by Sevage, papain, and trichloroacetic acid methods, and the antioxidant potential of PFSI by contrasting deproteinization methods based on free-radical scavenging capacity. The optimum conditions for UMSE extraction of PFSI were 500 W microwave power, 265.887 W ultrasonic power, 20.078 min extraction time, and 94.995:1 liquid-to-material ratio. Meanwhile, the sequence of the single factors on the yield of polysaccharides indicated that microwave power > extraction time > D liquid to material ratio > B ultrasonic power, and that the obtained average value of polysaccharide yield was 37.05%, which was analogous to the predicted value of 37.17%, indicating that the optimization method was reasonable. In vitro, the antioxidant assay demonstrated that PFSI, with or without deproteinization, had a definite capability to scavenge oxidative free radicals. This research provides a theoretical basis for the industrial production of PFSI as a natural antioxidant, and a scientific basis for its industrial development.