Ultrasound Assisted Aqueous Two‐Phase Extraction Process Optimization, Purification, Structural Characterization, and Antioxidant Activity of Polysaccharides From <i>Taraxacum mongolicum</i> Hand.‐Mazz

ABSTRACT The ultrasound assisted aqueous two‐phase extraction (UATPE) process of crude polysaccharides from Taraxacum mongolicum Hand.‐Mazz. (TMHPs) was optimized by an orthogonal test. A major homogeneous polysaccharide fraction (TMHPs‐1‐SG) was purified from the crude TMHPs via DEAE‐52 and Sephadex‐G150 column chromatography, and the structure of TMHPs‐1‐SG was characterized by using ultraviolet–visible spectroscopy (UV–vis), ion chromatography, high‐performance gel permeation chromatography (HPGPC), Fourier transform infrared spectroscopy (FT–IR), Congo red test, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), and then evaluated their antioxidant activity. The results show that the optimal extraction process was obtained as follows: the ammonium sulfate content of 24%, ethanol concentration of 45%, ultrasound power of 400 W, and solid‐to‐liquid ratio of 1:20 g/mL, and the yield of TMHPs was 12.06% ± 0.16%. TMHPs‐1‐SG with Mw of 11.30 kDa consisted of arabinose (Ara, 8.59%), glucose (Glc, 72.16%), and mannose (Man, 13.27%). TMHPs‐1‐SG showed the typical absorption patterns of polysaccharides. Moreover, TMHPs‐1‐SG did not have a triple helix structure and presented an irregular structure, and the surface of TMHPs‐1‐SG was smooth and attached with many spherical particles. Furthermore, the IC 50 values of TMHPs‐1‐SG for DPPH, ABTS + , OH, and O 2 − radicals scavenging rates were 0.57, 0.75, 0.74, and 0.58 mg/mL, respectively. The results provide a green and feasible strategy for the efficient extraction of natural polysaccharides.