2.2 Isolation and purification of polysaccharide
Briefly, the dry three-year roots of Radix ginseng (2,000 g) were smashed into crude powder (60-80 mesh) and extracted three times with water (20 L) by continuously stirring at 80 °C for two hours each time. The combined aqueous extracts were filtered through a cotton cloth bag and centrifuged (1,500 g for 15 min) and were subsequently concentrated in a rotary evaporator at 60 °C. Then, the ethanol solution was to a final concentration of 80%. The sediment was dissolved in water, continuously stirred at 4 °C for 12 hours, and the precipitate was removed by centrifugation (1,500 g for 15 min). The aqueous extract was then filtered and concentrated, followed by the addition of Sevage reagent (butanol and chloroform at a 1:4 ratio) to deproteinate the sample (Huang, Li, Wan, Zhang, & Yan, 2015). Then, the supernatant was concentrated to a proper volume under reduced pressure and lyophilized to get the GP.