辐照降解黄芪多糖及其抗氧化活性研究

Study on irradiation degradation and antioxidant activity of Astragalus polysaccharide

从黄芪中提取分离两组大分子黄芪多糖APS 1(分子量1.93×10^(6))和APS 2(分子量3.92×10^(5)),并采用γ射线(1~20 kGy)对其水溶液进行辐照降解处理。通过凝胶渗透色谱法、高效液相色谱和傅里叶变换红外吸收光谱分析方法,研究辐照对黄芪多糖分子量、结构组成以及回收率的影响。以对1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)抑制率为指标,对比辐照前后不同分子量黄芪多糖的抗氧化活性。结果显示:随着吸收剂量增大,APS 1分子量快速降低至2.33×10^(4),多糖回收得率降低至44.7%;APS 2分子量从3.92×10^(5)快速降低至2.54×10^(4),多糖回收得率降低至39.2%。在低剂量下通过多糖浓度控制,可有效实现分子量的逐步降低和高回收得率。辐照降解后,多糖、单糖组成和结构基本一致。APS 1对DPPH的抑制率随着分子量的降低从3.55%增大到20.53%,APS 2则从15.23%增大到29.61%。

Two groups of high molecular weight Astragalus polysaccharide(APS),APS 1(molecular weight of 1.93×10^(6))and APS 2(molecular weight of 3.92×10^(5)),were isolated from Astragalus membranaceus,and the two aqueous polysaccharide solutions were treated with g-irradiation at absorbed doses of 1~20 kGy.We studied the irradiation impact on APS molecular weight,structure composition,and recovery using gel permeation chromatography,high-performance liquid chromatography,and Fourier transform infrared spectrometry analyses.We compared the antioxidant activities of different molecular-weight APS before and after irradiation via the 1,1-diphenyl-2-picrylhydrazyl(DPPH)inhibition rate.The results showed that the molecular-weight of APS 1 rapidly degraded to 2.33×10^(4)with the increase in absorbed dose,and the polysaccharide recovery rate was decreased to 44.7%.The molecular weight of APS 2 decreased rapidly from 3.92×10^(5)to 2.54×10^(4),and the polysaccharide recovery rate decreased to 39.2%.The APS molecular weight could be effectively reduced gradually at a low absorbed dose with a high recovery rate by controlling the polysaccharide concentration.The monosaccharide composition and polysaccharide structure were essentially the same before and after the irradiation-induced degradation.The inhibition rate of APS 1 increased from 3.55%to 20.53%with the decrease in molecular weight.Finally,the DPPH inhibition rate of APS 2 increased from 15.23%to 29.61%with the decrease in molecular weights.