玉米须多糖的制备及体外抗氧化活性研究

Preparation of Corn Silk Polysaccharides and Study on Their Anti-oxidative Activity in Vitro

以水提醇沉法制备玉米须粗多糖,二乙胺基乙基纤维素(DEAE)离子交换柱层析法进行分离,分离组分采用高效凝胶渗透色谱法(HPGPC)测定其相对分子质量,并以清除1,1-二苯基-2-苦基肼(DPPH)自由基、邻苯三酚自氧化产生的超氧阴离子以及Fenton反应生成的羟基自由基等方法研究其体外抗氧化活性.实验结果表明,在提取温度100℃、提取时间2 h和料液比10∶150实验条件下玉米须粗多糖的提取率为3.03%;分离纯化得到中性和酸性多糖组分各一个,对应的重均分子量分别为364 754.0 Da和184 926.9 Da;多糖浓度为2.0 mg/mL时,中性多糖对1,1-二苯基-2-苦基肼自由基、超氧阴离子以及羟基自由基的清除率分别为4.158%、47.7%和43.8%,酸性多糖组分的相应清除率分别为-3.89%、53.2%和43.3%.玉米须中性多糖对1,1-二苯基-2-苦基肼自由基有微弱清除作用,而酸性多糖对自由基的生成具有很小的促进作用;两者都对超氧阴离子和羟基自由基具有一定的清除作用,但均低于维生素C.

The corn silk crude polysaccharides could be obtained by water extraction and alcohol precipitation, then DEAE（ diethylaminoethyl cellulose） ion exchange column chromatography was utilized for their separation. Their molecular weight was determined by high performance gel permeation chromatography （ HPGFC）, the corn silk polysaccharides were reacted with DPPH （ 1,1 -diphenyl- 2-picrylhydrazyl） free radical, superoxide anion from pyrogallol auto-oxidation and hydroxyl free radical from Fenton reaction to determine their anti-oxidative activity in vitro. The results indicated that the extraction rate of corn silk crude polysaccharides was 3.03%, on condition that the temperature was 100 ℃, the time was 2 h and ratio of solid to liquid was 10： 150. Two fractions were obtained, which were referred as neutral polysaccharides and acidic polysaccharides, and their average molecular weight was determined to be 364 754.0 and 184 926.9 Da, respectively. It was proved when the concentration of polysaccharides was 2.0 mg/mL, the clearances of DPPH free radical, superoxide anion and hydroxyl free radical were 4. 158% , 47.7% and 43.8% , respectively, for the neutral pol- ysaecharides. In addition, the relative clearances were -3.89% , 53.2% and 43.3%, respectively, for the acidic polysaccharides. The corn silk neutral polysaccharides processed a weak cleaning effect on DPPH free radical, however, the acidic polysaecharides could slightly promote the generation of DPPH free radical. Both of two fractions had positive cleaning effect on superoxide anion and hydroxyl free radical, but their anti-oxidative activity was lower than vitamin C.