羊栖菜褐藻糖胶的结构表征及其抗氧化活性

为研究羊栖菜褐藻糖胶的结构及其抗氧化活性,以羊栖菜为原料,经CaCl₂溶液提取、DEAE-Sepharose fast flow分离纯化得到褐藻糖胶组分SFP-2。采用高效凝胶渗透色谱法(HPGPC)、化学法、高效液相法(HPLC)以及傅里叶变换红外光谱法(IR)对多糖的纯度、分子量、理化性质、单糖组成以及官能团进行测定,并通过测定DPPH自由基清除活性、超氧阴离子清除活性、ABTS⁺自由基清除活性、亚硝酸盐清除活性和还原力,对多糖的体外抗氧化活性进行了评价。结果表明,SFP-2分子量均一,为707.0 kDa;总糖含量为66.9%,蛋白含量为3.1%,硫酸基含量为21.2%,不含糖醛酸;SFP-2主要由岩藻糖和半乳糖构成,还含有少量的甘露糖和氨基葡萄糖;红外光谱显示,SFP-2具有硫酸化多糖常见官能团的特征吸收峰;上述结果表明SFP-2是一种不含糖醛酸的硫酸化岩藻聚糖。SFP-2具有良好的清除DPPH自由基、超氧阴离子、ABTS⁺自由基、亚硝酸盐活性,其EC₅₀分别为8.94、8.30、16.04、9.87 mg/mL,且具有一定的还原能力。因此,SFP-2是一种不含糖醛酸的,抗氧化活性良好的羊栖菜褐藻糖胶。

Structural Characterization and Antioxidant Activities of Fucoidan from Sargassum fusiforme

In order to study the structural characterization and antioxidant activities of fucoidan from Sargassum fusiforme, a heterogeneous polysaccharide SFP-2 was obtained by CaCl₂ solution extraction and anion-exchange. Structural characterization of SFP-2 was preliminarily determined by high performance gel permeation chromatography (HPGPC), chemical methods, high performance liquid chromatography (HPLC) as well as fourier-tansform infrared (IR). The antioxidant activities were evaluated by scavenging assays involving DPPH radical, superoxide anion, ABTS+ radical, nitrite and reducing power. Results indicated that SFP-2 appeared as a single and symmetrical peak in the HPGPC chromatogram and the average molecular weight was 707.0 kDa. The contents of total sugar, protein and sulfate ester were 66.9%, 3.1% and 21.2%, respectively. No uronic acid was detected, SFP-2 was mainly composed of fucose and galactose with a small amount of mannose and glucosamine. IR further proved SFP-2 was a sulfated polysaccharide. From the results, SFP-2 was a sulfated fucoidan without uronic acid. SFP-2 had good scavenging activity for DPPH radical, superoxide anio, ABTS+ radical and nitrite. The EC₅₀ values of the scavenging assays were 8.94, 8.30, 16.04, 9.87 mg/mL, respectively, with the ability of reducing power. Results above indicated that SFP-2 was a kind of non-glucuronic acid fucoidan which had better antioxidant activity.