以油菜花粉多糖为原料,采用氢氧化钠-氯乙酸法,分别在0.5 mol/L和2.0 mol/L NaOH浓度条件下对油菜花粉多糖(rape pollen polysaccharides,RPP)进行羧甲基化修饰,并对其清除羟自由基(·OH)、超氧阴离子自由基(O2-·)和1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基的能力进行研究.结果表明:羧甲基与油菜花粉多糖形成羧甲基化合物,得到取代度分别为0.47和0.55的2个改性产物,羧甲基油菜花粉多糖1(Carboxymethylated rape pollen polysaccharide1,CM-RPP1)和羧甲基油菜花粉多糖2(Carboxymethylated rape pollen polysaccharide 2,CM-RPP2),RPP、CM-RPP1和CM-RPP2表现出不同程度的抗氧化活性,总的自由基清除能力大小为CM-RPP2>CM-RPP1>RPP.与未修饰油菜花粉多糖相比,羧甲基化修饰能提高油菜花粉多糖的体外抗氧化活性.%Polysaccharides from rape pollen (RPP) was carboxymethylated by alkaline chloroacetic acid at 0.5 mol/L and 2.0 mol/L NaOH respectively to obtain carboxymethylated rape pollen polysaccharides(CM-RPP).The scavenging capacities of hydroxyl free radicals, superoxide anion radical, 1,1-diphenyl-2-picrylhydrazyl were assayed,with vitamin C (VC) as control.The results were that two carboxymethylated polysaccharides of RPP with degree of substitution (SD) of 0.47 and 0.55, named carboxymethylated rape pollen polysaccharide1 (CM-RPP1) and carboxymethylated rape pollen polysaccharide 2(CM-RPP2), were obtained. RPP, CM-RPP1 and CM-RPP2 had certain scavenging ability to OH·free radical, O 2-·free radical and DPPH free radical. Total antioxidant activity was CM-RPP2>CM-RPP1>RPP. Compared with RPP, the antioxidant activity of polysaccha-rides in rape pollen can be improved through carboxymethylation.
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