Optimization for the extraction of polysaccharides from Gentiana scabra Bunge and their antioxidant in vitro and anti-tumor activity in vivo

• The extraction of polysacchrides from Gentiana scabra Bunge (GSP) was optimized.
• The predictive model of GSP extraction is adequate for the extraction process.
• GSP possessed a good antioxidant activity in vitro and anti-tumor activity in vivo.

Water-soluble polysaccharides were obtained from Gentiana scabra Bunge. Response surface methodology was used to optimize the extraction conditions, and a central composite design was adopted to determine the optimal processing parameters. The optimum extraction conditions are as follows: extraction temperature, 100 °C; ratio of water to raw material, 26.56; extraction time, 3 h; and extraction frequency, 2. Under these conditions, the experimental yield of polysaccharides was 13.0 ± 0.25%, which was consistent with the predicted yield. In vitro evaluation of the antioxidant activity suggests that the polysaccharides have high scavenging activity to 1,1-diphenyl-2-picrylhydrazyl radicals, relatively lower reducing power and scavenging activity to superoxide anions and hydroxyls. The polysaccharides also show high anti-tumor activity in vivo.