麦冬多糖MDG-1的分离纯化和结构分析

目的分离纯化麦冬多糖抗心肌缺血的活性部位，得到相对分子质量均一的组分MDG-1，并进行结构分析。方法水提醇沉得麦冬粗多糖，超滤后经DEAE Sepharose FF柱和Sephadex G25柱色谱纯化后得MDG-1。经完全酸水解、高碘酸氧化、Smith降解、甲基化分析、¹H NMR及¹³C NMR等研究分析MDG-1的化学结构。结果和结论 MDG-1为β-D-果聚糖，易溶于水，数均分子量(M_n)为3 400，重均分子量(M_w)为4 800，峰尖分子量(M_p)为5 000，以2→1连接的呋喃型果糖为主，平均每2.8个主链残基上有一个Fruf(2→6)Fruf(2→分支)。该多糖还含有微量葡萄糖(果糖∶葡萄糖=35∶1)，可能连接在多糖的还原端。

Isolation, purification and structural analysis of a polysaccharide MDG-1 from Ophiopogon japonicus

AIM: To separate and purify the anti-myocardial ischemic polysaccharide fraction with a homogenous molecular weight from Ophiopogon japonicus, then study the chemical structure of the parts. METHODS: Crude polysaccharides were prepared by extracting the tube root fraction of Ophiopogon japonicus with water, then precipitation with ethanol. From the crude polysaccharides, the polysaccharide of MDG-1 was separated and purified using ultrafiltration, DEAE Sepharose FF and Sephadex G-25 column chromatography. Its structure was studied by complete hydrolysis, periodate oxidation, Smith degradation, methylation analysis, 1H NMR and 13C NMR analysis etc. RESULTS AND CONCLUSION: MDG-1 was a water-soluble beta-D-fructosan, containing a backbone composed of Fruf (2 --> 1), and a branch of Fruf (2 --> 6) Fruf (2 --> per average 2. 8 of main chain residues. Mn, Mw and Mp of MDG-1 were 3 400, 4 800 and 5 000, respectively. MDG-1 contains trace of Glc, which maybe connect to its reducing terminal. Molar ratio of Fru and Glc is approximately 35: 1.