芫根是高原特有的经济作物，芫根多糖具有抗氧化、抗疲劳、抗缺氧等生物活性，为了探究芫根多糖的结构以及检测抗氧化活性，该文使用水提醇沉法提取粗多糖，分离纯化得到BRP-5，利用高效凝胶渗透色谱、离子色谱仪、扫描电镜、扫描隧道探针显微镜、红外光谱、同步热测量仪对其组成、形态和结构进行分析，以其清除超氧阴离子自由基、羟自由基、DPPH自由基能力评估体外抗氧化活性。结果表明，BRP-5是以半乳糖醛酸为主要单糖的酸性多糖，重均分子量为16670 Da，表面有裂纹和裂隙，最大高度（Ten Point Height，Sz）、根均方高度（Root Mean Square，Sq）、算术平均高度（Roughness Average，Sa）分别为24.40、2.84、2.01 nm，可能存在吡喃糖环，无定型结构。DPPH自由基和羟自由基清除率在0.1-1.5 mg/mL之间呈现剂量依赖性，半抑制浓度（50% Inhibiting Concentration, IC50）分别为0.96 mg/mL和低于0.1 mg/mL，超氧阴离子自由基清除率低于50%，BRP-5具有一定的抗氧化活性。研究结果可提高芫根多糖结构的了解，为相关抗氧化产品的开发提供理论依据。

Brassica rapa L. is an economic crop unique to the plateau. Polysaccharides from Brassica rapa L. possesses biological activities such as antioxidation, anti-fatigue, and anti-hypoxia. To investigate the structure of polysaccharides from Brassica rapa L. and examine its antioxidant activity, crude polysaccharides were extracted by the water extraction and ethanol precipitation method and BRP-5 was isolated and purified in this paper. The composition, morphology, and structure of BRP-5 were analyzed by using High-Performance Gel Permeation Chromatography, Ion Chromatography, Scanning Electron Microscopy, Scanning Tunneling Microscopy, infrared spectroscopy, and synchronous thermal measurement. The antioxidant activity in vitro was evaluated by its ability to scavenge superoxide anion radicals, hydroxyl radicals, and DPPH radicals. The results indicate that BRP-5 is an acidic polysaccharide with galacturonic acid as the main monosaccharide, with a weight-average molecular weight of 16,670 Da. Cracks and fissures were found on its surface, with Sz (Ten Point Height), Sq (Root Mean Square) and Sa (Roughness Average) being 24.40, 2.84, and 2.01 nm respectively. A pyranose ring and an amorphous structure might exist. The scavenging rates of DPPH radicals and hydroxyl radicals showed dose dependence within the range of 0.1 - 1.5 mg/mL, with 50% Inhibiting Concentration values of 0.96 mg/mL and less than 0.1 mg/mL respectively. The scavenging rate of superoxide anion radicals was less than 50%. A certain antioxidant activity was demonstrated by BRP-5. The research findings can enhance the understanding of the structure of polysaccharides from Brassica rapa L. and provide a theoretical basis for the development of related antioxidant products.

2021年度青海省“昆仑英才·高端创新创业人才”项目