秀珍菇多糖PMP-2a的理化性质及其体外抗氧化活性研究

Physicochemical Characteristics and in vitro Antioxidant Activity of Polysaccharide PMP-2a from Pleurotus geesteranus

摘要:

本文以秀珍菇菌丝体为原料提取水溶性粗多糖，经脱蛋白、脱色、DEAE-Sepharose F.F和Superdex-200柱层析纯化，得到一种秀珍菇菌丝体多糖（PMP-2a）。高效液相色谱鉴定其纯度；比色法测定其总糖、糖醛酸、蛋白质含量；紫外光谱、红外光谱、β-消去等方法研究其理化性质和部分结构；通过清除超氧阴离子自由基、羟基自由基来研究PMP-2a的体外抗氧化活性。结果表明，PMP-2a为均一组分，其中性糖部分由鼠李糖（Rha）、葡萄糖（Glc）、半乳糖（Gal）、甘露糖（Man）、阿拉伯糖（Ara）组成（摩尔比为1:13.18:2.19:7.23:3.15）；其总糖、糖醛酸、蛋白质含量分别为82.6%、19.8%、10.6%，不含有核酸；红外光谱呈现典型的多糖特征峰，含有α-D-吡喃糖苷键；相对分子质量为9.28×104 Da，β-消去反应表明糖链与蛋白之间存在-O-的连接键；PMP-2a对超氧阴离子自由基、羟基自由基的清除效果显著，且与多糖浓度呈明显的量效关系。

Abstract:

In this study, a water-soluble, crude polysaccharide was extracted from Pleurotus geesteranus and the mycelium polysaccharide was obtained by deproteinization, discoloration, and purification using diethylaminoethanol (DEAE)-Sepharose Fast-Flow ion-exchange chromatography and Superdex-200 column chromatography. The purity of the polysaccharide was determined using high-performance liquid chromatography (HPLC); Colorimetric measurement of the total sugar, uronic acid and protein content; and physicochemical properties and partial structural characteristics, studied by ultraviolet (UV), infrared (IR) and β-elimination reaction methods. The in vitro antioxidant activity of PMP-2a was determined by superoxide radical and hydroxyl radical scavenging assays. The results showed that PMP-2a was a homogeneous polysaccharide, consisting of Rha, Glc, Gal, Man, and Ara in a molar ratio of 1:13.18:2.19:7.23:3.15. The total sugar, uronic acid, and protein content of PMP-2a were 82.6%, 19.8%, and 10.6%, respectively; no nucleic acid was found. Typical absorption bands of polysaccharides and glycosidic bonds in α-D-pyranoside were found in the IR spectrum. The molecular weight was 9.28 × 104 Da, and the β-elimination reaction indicated that PMP-2a was linked to peptide chains through an -O- bond. PMP-2a showed significant superoxide radical- and hydroxyl radical-scavenging activities in a dose-dependent manner.