天麻多糖分离、结构分析与自由基清除作用研究

目的：研究活性天麻多糖的提取、结构分析与自由基清除作用。方法：以水提醇沉法制备天麻粗多糖，CTAB 季铵盐络合法、凝胶过滤柱层析进一步纯化；通过IR、NMR 等分析天麻多糖结构；利用Feton 体系和邻苯三酚自氧化反应，采用比色法测定天麻多糖对·OH 及O2·的清除作用。结果：通过正交试验获得天麻多糖提取工艺为：料水比1:40，浸提温度80℃，提取次数2 次，75% 乙醇沉淀；红外光谱和1H-NMR 分析天麻多糖为α- 吡喃己糖，单糖分析结果显示它为单一葡萄糖残基组成，13C-NMR 分析表明天麻多糖为带1 → 6 键接支链的α-(1 → 4)-D- 葡聚糖；在相同的实验体系浓度下，天麻粗多糖及纯化多糖对·OH 的IC50 分别为1.18、1.62mg/ml；对O2·的IC50 分别为0.81、1.03mg/ml。结论：天麻多糖为1 → 6 键接支链的α-(1 → 4)-D- 葡聚糖，对O2·具有一定清除能力。

Study on Extraction Technology, Structure and Free Radical Scavenging Activity of Polysaccharides from Gastrodia elata B1

Polysaccharides were extracted from Gastrodia elata B1 with water and precipitated by ethanol, purified through cetyltrimethylammonium bromide (CTAB) complex method and Sepharose 6-fast flow chromatography. The structural characterization of Gastrodia elata B1 polysaccharides (GPS) was conducted by means of IR and NMR techniques. In simulated chemical reaction system, the scavenging effects of GPS on ·OH and O2· were investigated via Fenton reaction and pyrogallol autoxidation method repectively. Results showed that the optimal extraction technology conditions are as follows: extraction temperature 80 ℃, extraction times 2, solid-liquid ratio 1:40 and using 75% ethanol as precipitant. IR and 1H-NMR analysis indicated that GPS are composed of D-glucopyranose. The 13C-NMR results revealed that GPS are a (1→4) linked α-D-glucan, which is attached by glucosyl side chains at O-6 of the glucosyl residues of main chain. The IC50 of crude GPS and purified GPS to ·OH are 1.18 mg/ml and 1.62 mg/ml respectively, and those O2· are 0.81 mg/ml and 1.03 mg/ml respectively. In conclusion, GPS have a structure of (1→4) linked α-D-glucan with branching residues and certain capacity of scavenging free radicals.