Zhang Bi-Wei, Xu Jin-Long, Zhang Hua, Zhang Qiang, Lu Jie, Wang Jun-Hui
School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, People's Republic of China.
Anhui Qiangwang Flavouring Food Co., LTD, Dongcheng Development Zone, Jieshou City, Anhui, China.
PLoS One. 2016 Dec 20;11(12):e0168472. doi: 10.1371/journal.pone.0168472. eCollection 2016.
Umbilicaria esculenta has been used as a tonic food in China for several centuries owing to its pleasant flavor and health benefits. In this study, a water soluble polysaccharide, which we designated as UP2, with an average molecular weight of 3.33 × 105 Da, was isolated from U. esculenta cultivated in the Huangshan Mountain, by consecutive hot water extraction and anion-exchange chromatography. Gas chromatography analysis indicated that UP2 contained three kinds of monosaccharides, including mannose, glucose, and galactose at a molar ratio of 1.7:1.0:1.2. Linkage analysis of UP2 revealed the presence of (1 → 6)-linked glucosyl, (1 → 3,6)-linked glucosyl, t-linked galactosyl, (1 → 6)-linked galactosyl and (1 → 6)-linked mannosyl at a molar ratio of 0.7:4.6:4.1:2.2:9.1. Structural analysis determined that UP2 possessed a backbone consisting of (1 → 6)-linked β-D-glucopyranosyl and (1 → 6)-linked α-D-mannopyranosyl residues, which substituted at the O-3 position of (1 → 6)-linked β-D-glucopyranosyl residues by branches of (1 → 6)-linked α-D-galactopyranosyl and 1-linked β-D-galactopyranosyl residues. Immunostimulatory activity analysis showed that UP2 could stimulate the proliferation of RAW264.7 cells in a dose-dependent manner, and all the samples (20-500 μg/mL) were found to enhance nitric oxide production. The highest phagocytic activity of UP2 was observed at 200 μg/mL. Thus, UP2 may be a potential source of biological and pharmacological agents.
由于美味的口感和对健康的益处，石耳在中国已被用作滋补食品达几个世纪之久。在本研究中，通过连续热水提取和阴离子交换色谱法，从黄山种植的石耳中分离出一种水溶性多糖，我们将其命名为UP2，平均分子量为3.33×10⁵Da。气相色谱分析表明，UP2含有三种单糖，包括甘露糖、葡萄糖和半乳糖，摩尔比为1.7:1.0:1.2。UP2的连接分析显示存在(1→6)-连接的葡萄糖基、(1→3,6)-连接的葡萄糖基、t-连接的半乳糖基、(1→6)-连接的半乳糖基和(1→6)-连接的甘露糖基，摩尔比为0.7:4.6:4.1:2.2:9.1。结构分析确定，UP2具有由(1→6)-连接的β-D-吡喃葡萄糖基和(1→6)-连接的α-D-吡喃甘露糖基残基组成的主链，这些残基在(1→6)-连接的β-D-吡喃葡萄糖基残基的O-3位被(1→6)-连接的α-D-吡喃半乳糖基和1-连接的β-D-吡喃半乳糖基残基的分支取代。免疫刺激活性分析表明，UP2可以剂量依赖性方式刺激RAW264.7细胞的增殖，并且发现所有样品（20-500μg/mL）均可增强一氧化氮的产生。在200μg/mL时观察到UP2的最高吞噬活性。因此，UP2可能是生物和药理活性剂的潜在来源。
