【作者】 吕丽爽；

【导师】 汤坚；

【作者基本信息】 江南大学 ， 食品科学， 2006， 博士

【摘要】 何首乌（Polygonum multiflorum Thunb）为蓼科多年生草本植物的块根,是我国传统的延年益寿的中草药。何首乌中主要的功效性成分二苯乙烯苷近年来成为研究的热点。文献报道了其多项生理功能:抗氧化、清除自由基;抗肿瘤;降低胆固醇;抑制动脉粥样状硬化;保护肝脏;具有血管舒张作用;防治老年痴呆;提高记忆等功效。其间以抗氧化、清除自由基性能最为突出。故本课题以贵州何首乌为原料,建立了分离纯化的工艺路线,分离制备得到二苯乙烯苷晶体,深入探讨了二苯乙烯苷抗氧化性能及抗氧化机理,为进一步研究何首乌的药理提供了理论基础。在分析选取何首乌原料后,研究二苯乙烯苷的分离提取工艺。运用溶剂提取、壳聚糖絮凝澄清、大孔吸附树脂分离技术分离纯化何首乌中二苯乙烯苷。首先,通过单因素、中心组合实验,运用响应面分析法优化了水提取工艺条件,得到最佳条件为:固-液比1:15,温度50℃,时间40min。而后,对水提浓缩液选用壳聚糖为絮凝剂进行了澄清以除去蛋白、果胶等大分子杂质,通过正交实验得到最佳条件为:壳聚糖添加量:0.3mg/mL,pH值4.5,温度20℃。最后,对15种大孔吸附树脂进行静态吸附实验,优选出5种吸附率高,解吸效果良好的树脂进行了静态吸附动力学、静态吸附等温线方程的拟和实验,考察了树脂的吸附速率以及溶液浓度与饱和吸附量了的关系,最终选出大孔吸附树脂HPD100作为分离纯化二苯乙烯苷的最佳树脂。继而分别对树脂的动态吸附条件:进样浓度、流速、进样pH值、洗脱溶液进行了优化,最终确定相关柱条件,洗脱方式为先用20%乙醇洗脱除去部分杂质,在用40%乙醇洗脱目标产物二苯乙烯苷,使得最终产物纯度为84.47%,得率为75.12%。应用聚酰胺柱层析系统初步纯化了何首乌的乙醇粗提液,而后通过溶剂结晶技术,首次分离得到了二苯乙烯苷白色针状晶体,液-质（LC-MS）联用测定纯度为99.49%,相对分子质量为406;通过核磁共振分析（NMR）鉴定其结构;并运用X-射线衍射、差示扫描量热分析（DSC）、热重分析（TGA）等技术对晶体性质进行了初步测定,证明二苯乙烯苷不存在同质多晶现象,仅有一种针状晶体存在形式,且不含结晶水,熔点为151.33℃。以BHT、Vc、白藜芦醇（RE）为对照,分别对二苯乙烯苷（SG）、大孔吸附树脂分离样品（RF-SG）、何首乌粗提物（C-SG）体外抗氧化性能进行测定。考察了亚油酸体系抗氧化性,还原性,DPPH自由基、超氧阴离子、羟自由基、H₂O₂清除能力以及金属鏊合性。得出结论:从何首乌中提取的不同纯度的二苯乙烯苷样品均具有抗氧化、清除自由基功能。其活性强弱依次为SG、RF-SG、C-SG。与常用抗氧化剂BHT、Vc对照,SG亚油酸体系抗氧化性、还原性、清除DPPH自由基能力相对较弱;而清除超氧阴离子、羟基自由基、H₂O₂能力要高于BHT、Vc。而与结构相似的RE对照,SG优于RE,原因是在结构上SG比RE多形成了一个（2-O-Glu）糖苷;由此2-糖苷的推电子效应,可以使对位羟基（C5-OH）所形成的苯氧自由基更为稳定,以便终止自由基链反更多还原

【Abstract】 Polygonum multiflorum Thunb(PM) is an earthnut plant and is typically traditional anti-aging herb in China. A lot of research has been carried out on the main functional compound-stilbene glycoside (SG) from PM in recent years. SG serves several functions, such as: antioxidant activity and free radical scavenging, anti-tumour effect, cholesterin reduction, atherosclerosis inhibition, liver protecting, vasodilation, prevention of aging dementia, improve memory etc. Antioxidant activity is the major functionality of SG. In this dissertation, the crystal of SG was separated from PM harvested in Guizhou province, and its antioxidant activity and the mechanism were studied. Also, the isolation and purification of SG from PM was conducted.The extraction and isolation of SG from PM were optimized. SG was extracted by water from PM. The optimal conditions were:50℃, 1:15 solid /liquid ratio and for 40min. Secondly, Chitosan was used to clarify crude extract of PM, and the best parameters were: chitosan addition quantity 0.3mg/mL, pH 4.5, and 20℃. Finally, macroporous adsorbent resin separation SG was carried out. On comparing the adsorption and desorption performance of 15 kinds of macroporous adsorbent resin by static adsorption test, 5 kinds of resin were picked out. Through static experiments on Freundlich and Langmuir adsorption isotherm, HPD-100 macroporous adsorbent resin was selected for it excellent performance. Afterward, the effect of concentration, pH, eluted solution and speed of infusion of HPD-100 resin were studied with dynamic adsorption test. The result showed that impurities were removed by using 20% EtOH, then SG was eluted with 40% EtOH, Thence the final product was obtained with a purity of 84.47%, and yield ratio of 75.12%. Column chromatography of polycaprolactam was used to separate EtOH extracts of PM,and then an acicular crystal was obtained by solvent evaporation. The purity of stilbene glycoside was 99.49% by HPLC analysis. The structure of crystals was determined by NMR and X-ray diffraction analysis. The physical property of crystals was also tested on DSC and TGA. The result showed that there was no polymorphism and only one acicular crystal of SG was observed. The melting point of SG was 151.33℃.Antioxidant activitity of SG, the fraction of resin (RF-SG) and ethanol extracts of PM (C-SG) were investigated. The antioxidant properties of extracts of PM were evaluated using different antioxidation tests, including reducing power, inhibition to lipid oxidation (ferric-thiocyanate), DPPH radical scavenging, superoxide anion radical scavenging, hydroxyl radical scavenging, hydrogen peroxide scavenging, and metal chelating activity, Butylated hydroxytoluene (BHT) and Vc were used as references. At the same time, the various antioxidant activities were compared with that of resveratrol (RE: a kind of structure analog).更多还原