Extraction, Characterization, Antioxidant, and Immunostimulatory Activities of Polysaccharides from Hedyotis corymbosa

In this study, optimization of enzyme-assisted extraction, purification, characterization, and its bioactivities of polysaccharides from Hedyotis corymbosa (HCP) was investigated. It was found that the optimum extraction conditions were 3% of enzyme concentration (X(1)), 30 of liquid-to-solid ratio (X(2)), 56°C of extraction temperature (X(3)), 200W of ultrasonic power (X(4)), 10 min of extraction time (X(5)), and 5 of pH value (X(6)). Under optimum conditions, the experimental yield (4.10 ± 0.16%) was closed to the predicted value (4.02%). The crude HCP was further purified using DEAE-52 and Sephadex G-150 gel column, and a major polysaccharide fraction from HCP, designed as HCP-1a with molecular weight of 33.9 kDa, was obtained. The HCP and HCP-1a were characterized by chemical analysis, FT-IR, and HPLC. For antioxidant activities in vitro, HCP possessed strong hydroxyl radical scavenging, DPPH radical scavenging, and Fe(2+) chelating activities. In subsequent immunostimulatory studies, significantly decreased NO, IL-1β, and TNF-α concentrations were observed in both of HCP and HCP-1a treated RAW264.7 cells. Therefore, this study may indicate some insights into the application of polysaccharides from Hedyotis corymbosa as potential natural antioxidants and immunostimulants.