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目的探究红树林放线菌Streptomyces sp.CHQ-61产生的胞外多糖的结构及自由基清除活性。方法利用乙醇沉淀法、阴离子交换层析柱和凝胶层析柱对菌株发酵产物中的胞外多糖进行分离纯化,运用核磁共振、气质联用色谱、红外光谱、高效凝胶渗透色谱和柱前衍生高效液相色谱分析鉴定多糖的结构特征,采用DPPH、超氧阴离子和羟基自由基清除率评价胞外多糖的抗氧化活性。结果从红树林放线菌Streptomyces sp.CHQ-61发酵产物中分离得到多糖XH-1,其分子量为8.9kDa,丙酮酸含量为4.0%,主要由半乳糖和氨基葡萄糖组成,糖链主要含有(1→6)Galp,还有少量的(1→3)GlcNp、(1→4,6)Galp、(1→3,6)GlcNp、末端Galp和GlcNp,XH-1具有一定的体外自由基清除活性,其清除DPPH、超氧阴离子和羟基自由基的EC50分别为0.5、0.8和3.0mg/mL。结论本文首次报道了红树林根泥放线菌Streptomyces sp.CHQ-61产生的胞外多糖XH-1为1种含有丙酮酸的半乳糖和氨基葡萄糖组成的结构新颖的胞外多糖,其具有较强的体外自由基清除活性。
Objective To investigate the structure and free radical scavenging activity of extracellular polysaccharides produced by Streptomyces sp. CHQ-61. Methods The extracellular polysaccharides in the fermentation products were isolated and purified by ethanol precipitation, anion exchange chromatography and gel filtration. The products were characterized by 1H NMR, GC-MS, FTIR, GPC and HPLC Derivative high performance liquid chromatography (HPLC) was used to identify the structural characteristics of polysaccharides. The antioxidant activity of exopolysaccharide was evaluated by DPPH, superoxide anion and hydroxyl radical scavenging rate. Results The polysaccharide XH-1 was isolated from the fermentation product of Streptomyces sp. CHQ-61 and its molecular weight was 8.9kDa and the content of pyruvate was 4.0%. It mainly consisted of galactose and glucosamine. The sugar chain mainly contained ( 1 → 6) Galp, a small amount of (1 → 3) GlcNp, (1 → 4,6) Galp, (1 → 3,6) GlcNp, Galp and GlcNp, XH- EC50 of DPPH, superoxide anion and hydroxyl radical were 0.5, 0.8 and 3.0 mg / mL, respectively. Conclusions This paper reports for the first time that extracellular polysaccharide XH-1 produced by mangrove root actinomycete Streptomyces sp. CHQ-61 is a novel extracellular polysaccharide composed of pyruvate-containing galactose and glucosamine, Strong in vitro free radical scavenging activity.