龙眼多糖清除自由基活性的研究

Study on Free-radical Scavenging Activities of Polysaccharide Extracts from Longan

从清除1,1-二苯基-2-苦苯肼自由基(DPPH·)、羟基自由基(·OH)和超氧阴离子(O2-·)三个方面,探讨纯化方法对龙眼多糖清除自由基活性的影响.以抗坏血酸为对照,利用分光光度法分别测定龙眼粗多糖(CLPS)、Sevag法脱蛋白制得的龙眼粗多糖半纯品(SLPS)、TCA法脱蛋白制得的龙眼粗多糖半纯品(TLPS)、经DEAE-Cellulose 52离子交换柱层析纯化得到的龙眼多糖纯品(LPS-2)对DPPH·、·OH和O2-·的清除能力.结果显示:多糖纯度越高,清除DPPH.活性也越强,其清除活性由强到弱依次为:LPS-2>TLPS>SLPS>CLPS;对于.OH和O2-·,SLPS清除活性最强,LPS-2清除活性最弱,说明杂蛋白质抑制了多糖清除.OH、O2-·活性,而糖蛋白中的蛋白质则起到促进作用.

The effect of purification technique on free-radical scavenging activities of polysaccharide extracts from longan was compared towards 1,1-diphenyl-2-picrylhydrazyl radical （ DPPH·）, hydroxyl radical （·OH） and superoxide anion radical （O2-· ）. With ascorbie acid as comparison, the scavenging abilities were determined by spectrophotometry against DPPH· , OH produced by Fenton reaction and O2-· generated by pyrogallol autoxidation of the crude longan polysaccharide （CLPS）, semi-pure longan polysaccharide product （Sl.JX3） prepared by removing its protein with the Sevag method, semi-pure longan polysaccharide product （TLPS） prepared by removing its protein with the TCA method, pure longan polysaeeharide （LPS-2） purified by DEAE-Cellulose 52 ion-exchange chromatography, respectively. The results showed that the higher the purity of polysaccharide, the stronger the scavenging activity to DPPH · , and the order of activity from greatness to weakness was ： LPS-2 〉 TLPS 〉 SLPS 〉 CLPS; in addition, as for ·OH and O2 , the activity of SLPS was the strongest and the LPS-2 was the weakest, which implied that the morley protein inhibited the scavenging activities to · OH and O2- · Nevertheless the protein moiety in glycoprotein promoted the activities.