龙眼多糖清除自由基活性的研究

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）、TEA法脱蛋白制得的龙眼粗多糖半纯品（TLPS）、经DEAE-Cellulose52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〉ELPS；对于·OH和O2^-·，SLPS清除活性最强，ITS-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．

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

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.