本采用热水浸提紫芝菌丝体得到粗多糖后经DEAE-sepharose Fast Flow和Sephacryl S-200 HR分离纯化出一种新型的灵芝多糖LZ1。通过采用凝胶渗透色谱法、电镜、紫外、红外光谱、气相色谱、核磁共振、高碘酸氧化和Smith降解方法等方法对LZ1进行结构鉴定和解析，结果表明LZ1是不含核酸、蛋白质的均一多糖，其分子量为7498 u；其是由鼠李糖、岩藻糖、甘露糖、葡萄糖、半乳糖和阿拉伯糖以0.94:0.50:1.68:26.91:4.80:17.12的摩尔比组成的酸性杂多糖，其糖苷键为1→4、1→2或1→6、1→3；刚果红实验表明LZ1没有三螺旋结构；通过小鼠巨噬细胞RAW264.7体外免疫模型，研究LZ1对TNF-α、IL-6、NO三种细胞因子的分泌情况的影响发现LZ1对这三种细胞因子的分泌有明显的促进作用，且呈现浓度相关性，表现出明显的免疫活性；通过AAPH诱导的红细胞氧化性溶血模型对LZ1的抗氧化活性进行评价，发现LZ1有很好的抑制AAPH诱导的红细胞氧化溶血的特性。

A new polysaccharide LZ1 was isolated and purified using DEAE-Sepharose Fast Flow and Sephacryl S-200 HR from crude polysaccharide extract obtained from Ganoderma lucidum mycelium via hot-water extraction. The structure of LZ1 was identified and elucidated by gel permeation chromatography (GPC), scanning electron microscopy (SEM), ultraviolet spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, gas chromatography (GC), nuclear magnetic resonance (NMR) spectroscopy, periodate oxidation, and Smith degradation. The results showed that LZ1 was a homogeneous polysaccharide and did not contain impurities such as proteins and nucleic acids. The molecular weight (Mw) was determined to be 7498 u by GPC. LZ1 was an acidic polysaccharide and consisted of rhamnose, fucose, mannose, glucose, galactose, and arabinose at a molar ratio of 0.94:0.50:1.68:26.91:4.80:17.12. The main glycosidic linkage types were 1→4 and 1→2 or 1→6 and 1→3. Congo red test suggested that there were no triple helical structures in LZ1. The effect of LZ1 on the expression of tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), and nitric oxide (NO) was studied using murine macrophage RAW264.7 cells as an in vitro immunomodulatory model. The results showed that LZ1 significantly promoted the secretion of TNF-α, IL-6, and NO in a concentration-dependent manner, and exhibited excellent immunomodulatory activity. Evaluation of the antioxidant activity of LZ1 by a 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced oxidative hemolysis model in erythrocytes suggested that LZ1 could effectively inhibit the AAPH-induced oxidative hemolysis of erythrocytes.

广州省科技计划项目（2016A040402020）；广东省科技计划项目（2016B010121014）