Abstract:

The extraction yield of Gynura divaricata (L.) DC. polysaccharides affected by extraction temperature, time and times and solid/liquid ratio was optimized by single factor and orthogonal array design methods. In addition, the removals of protein by the Sevag method and of color with hydrogen peroxide or activated carbon from the crude polysaccharide extract obtained were investigated. The anthranone-sulphuric acid method was used for polysaccharide determination. Result showed that a maximum polysaccharide yield was achieved through the optimal twice extraction for 3.5 h each time at 100 ℃ at 1:7 solid/ liquid ratio (g/mL). The optimal solvent for the removal of protein was a mixture of chloroform and n-butanol (4:1, V/V). The addition of 0.15 g/mL activated carbon aqueous suspension for twice treatment for 45 min at 80 ℃ or the addition of 70% (V/V) hydrogen peroxide for 120 min treatment at 60 ℃ gave an optimal removal of color. The procedure proved to be simple, feasible, effective and stable so as to be most suitable for the extraction and purification of polysaccharide from Gynura divaricata (L.) DC..

Key words: Gynura divaricata (L.) DC., polysaccharide, extraction and purification, determination