Extraction, separation, and antioxidant activity of polysaccharides from peony seed shell

This work evaluated the extraction, purification, and enrichment process of peony seed shell (PSS) polysaccharides, and explored the structural characteristics and the antioxidant activity of the polysaccharides. In this study, water was used as the solvent in combination with ultrasonic-assisted extraction technology to extract polysaccharides from PSS, and the extraction process was refined and optimized. The optimal extraction conditions were obtained as follows: liquid-to-solid ratio of 15 mL/g, power ratio of 65 %, extraction time of 25 min, and extraction temperature of 44 degrees C. The obtained polysaccharide solution was precipitated with 80 % ethanol and 100 % ethanol to obtain polysaccharides PP-a and PP-b, with yields of 1.39 % and 1.11 %, respectively. The crude polysaccharide was removed from protein by enzymatic method, followed by further separation and purification using DEAE-52 and Sephadex G-100 column chromatography. Two polysaccharide components, PP-a-3 and PP-b-1, were successfully obtained. The structures of the two polysaccharides were identified using methods such as Fourier-Transform Infrared Spectroscopy (FT-IR), monosaccharide composition analysis, methylation analysis, and nuclear magnetic resonance (NMR) spectrum. The results implied that PP-a-3 was mainly composed of (1-*4,5)-arabinose and (1-*2,4,5)-galactose, while PP-b-1 was mainly composed of (1-*4,5)-arabinose. The results of in vitro antioxidant activity suggested that PP-a-3 and PP-b-1 exhibited enhanced antioxidant capacity with increasing concentration in the range of 1-8 mg/mL. The results revealed that the two polysaccharides had good antioxidant properties and could be used as natural antioxidants. This study laid the research foundation for the deep development and utilization of oil tree peony, and also provided the reference for the further study and development of active ingredients in natural products.