该研究以酶解- 超声辅助法提取得到的淮山粗多糖为原料，采用凝胶柱进行分离纯化，进而采用高效液相色谱、超高效聚合物色谱系统、傅里叶红外变换光谱和扫描电镜对其结构进行分析，并探究了其铁离子还原能力和氧自由基清除能力。结果发现粗多糖经纯化后得到3个多糖级分，其中CYP-Ⅲ得率最高（65.2%），其次是CYP- Ⅱ（4.2%）和CYP-Ⅰ（2.5%）；红外光谱显示，三种多糖级分存在着吡喃糖且含有α-糖苷键，但CYP-Ⅰ中含有更多的羧基；CYP-Ⅰ是杂多糖（甘露糖38.29%、半乳糖30.61%、葡萄糖21.41%），分子量最大（5.1 ku），抗氧化活性最强；CYP-Ⅱ主要由葡萄糖（87.92%）聚合而成，分子量为4.0 ku；CYP-Ⅲ是葡聚糖（葡萄糖99.09%），分子量为2.5 ku，抗氧化活性最弱；扫描电镜结果显示CYP-Ⅰ分布无序，呈团簇状聚集且存在许多孔隙；CYP-Ⅱ表面较为紧密但凹凸不平；CYP-Ⅲ表面光滑但分布杂乱。结果表明在本研究中淮山多糖的的抗氧化活性与其酸性糖、甘露糖、半乳糖、鼠李糖和羧基含量成正相关。该研究可为淮山多糖的开发利用提供理论依据。

In this study, crude polysaccharide isolated from Chinese yam by enzymatic hydrolysis and ultrasoundassisted extraction, was separated and purified using a gel column, and then subjected to structural analyses by high performance liquid chromatography, ultra-high performance polymer chromatography, Fourier transform infrared spectroscopy, and scanning electron microscopy. Moreover, its ferric ion reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) were examined. The results revealed that the crude polysaccharide after purification yielded three polysaccharide fractions. The yield of the third fraction, CYP-III, was the highest (65.2%), followed by CYP-II (4.2%) and CYP-I (2.5%). Fourier transform infrared spectroscopy revealed that all three polysaccharide fractions contained pyranose and α-glycoside bonds, but CYP-I contained a higher amount of carboxyl groups. CYP-I was identified as a heteropolysaccharide composed of mannose (38.29%), galactose (30.61%), and glucose (21.41%), and had the highest molecular weight (5.1 ku) and the strongest antioxidant activity. CYP-II was found to be composed mainly of glucose (87.92%) and had a molecular weight of 4.0 ku. CYP-III was identified as a glucan (glucose 99.09%) with a molecular weight of 2.5 ku and the weakest antioxidant activity. The scanning electron microscopy examination revealed that CYP-I was disordered and appeared in clusters with numerous pores; CYP-II had a ompact but uneven surface, whilst CYP-III had smooth surfaces but distributed randomly. The results showed that the antioxidant activity of Chinese yam polysaccharide in this study was significantly positively correlated with the contents of acid sugars, mannose, galactose, rhamnose, and carboxyl groups. This study can provide a theoretical basis for the development and utilization of yam polysaccharides.

广东省重点研发计划项目（2022B0202020004）；国家重点研发计划项目（2021YFD1600103）；广东省特支计划本土创新团队项目（2019BT02N112）