Optimized Extraction, Preliminary Characterization, and In Vitro Antioxidant Activity of Polysaccharides from Glycyrrhiza Uralensis Fisch

BACKGROUND This study performed optimized extraction, preliminary characterization, and in vitro antioxidant activities of polysaccharides from Glycyrrhiza uralensis Fisch. MATERIAL AND METHODS Three parameters (extraction temperature, ratio of water to raw material, and extraction time) were optimized for yields of G. uralensis polysaccharides (GUP) using response surface methodology with Box-Behnken design (BBD). The GUP was purified using DEAE cellulose 32-column chromatography. The main fraction obtained from G. uralensis Fisch was GUP-II, which was composed of rhamnose, arabinose, galactose, and glucose monosaccharide, was screened for antioxidant properties using DP Hand hydroxyl radical scavenging assays. In addition, immunological activity of GUP-II was determined by nitric oxide and lymphocyte proliferation assays. RESULTS Optimization revealed maximum GUP yields with an extraction temperature of 99°C, water: raw material ratio of 15: 1, and extraction duration of 2 h. GUP-II purified from G. uralensis Fisch had good in vitro DPPH and hydroxyl radical scavenging abilities. Immunologically, GUP-II significantly stimulated NO production in RAW 264.7 macrophages, and significantly enhanced LPS-induced lymphocyte proliferation. CONCLUSIONS Extraction of GUP from G. uralensis Fisch can be optimized with respect to temperature, extraction period, and ratio of water to material, using response surface methodology. The purified product (GUP-II) possesses excellent antioxidant and immunological activities.