【作者】 开桂青；

【导师】 潘见；

【作者基本信息】 合肥工业大学 ， 农产品加工及贮藏工程， 2008， 博士

【摘要】 乌苏烷型和齐墩果烷型五环三萜在自然界分布广泛,且具有很好的药理活性。然而,这类同分异构体和以其为母体的衍生物常相伴而生,它们的结构差异仅在母体E环的甲基异构,理化性质极其相似,采用传统的色谱分离方法难以实现理想的分离效果。因此,如何有效地分离此类同分异构体成为急待解决的问题。本文拟采用超分子配位色谱法解决乌苏烷型和齐墩果烷型五环三萜同分异构体的分析检测问题。基于这种伴生型异构体的结构差异以及环糊精的超分子配位能力,筛选合适的配位剂;选择亲水性由高到低的三对同分异构体,建立其配位色谱分离方法;结合色谱分离的结果及其它相关的试验结果,从中总结出这种伴生型同分异构体实现高效分离的规律,其研究结果如下:1、采用ChemBioOffice 2005和Pymol Version 0.99计算了该类同分异构体的分子结构直径。发现其直径与β-环糊精的空腔直径相匹配;利用分子力学（MM₂）能量最小原则计算了目标物质与β-环糊精形成包合物前后体系的最小结合能,比较得出形成包合物后体系的最小能量明显降低。依几何匹配和能量匹配原则,优选出β-环糊精及其衍生物作为分离五环三萜类乌苏烷型和齐墩果烷同分异构体的配位剂。2、建立了羟基积雪草苷和积雪草苷—B、羟基积雪草酸和terminolic acid、齐墩果酸和熊果酸三对同分异构体的色谱分离方法。以β-环糊精或葡萄糖基-β-环糊精为流动相添加剂,在4mmol/L同浓度的环糊精下,异构体的分离度为:积雪草苷和积雪草苷—B（3.08,4.65）＞羟基积雪草酸和terminolic acid（2.02,2.65）＞齐墩果酸和熊果酸（未达到基线分离）;对于积雪草苷和积雪草苷—B、羟基积雪草酸和terminolic acid,分离能力是:葡萄糖基-β-环糊精＞β-环糊精;而对于分离齐墩果酸和熊果酸,葡萄糖基-β-环糊精的分离效果比β-环糊精的分离效果略差。在色谱分离过程中,分离度和该类异构体母体上的取代基密切联系,疏水基团的差异起主要作用。3、相同的环糊精浓度下,RpC₁₈色谱柱的分离度0.77略小于RpC₈色谱柱的分离度1.08,RpC₈色谱柱有利于异构体的分离;电喷雾质谱法没有观察到色谱过程中异构体和环糊精任何形式包合物的分子离子峰,表明在动态的色谱过程中异构体没有和环糊精形成稳定的包合物。提示:在色谱分离过程中疏水效应起主要作用,环糊精和色谱柱的配位—协同作用导致了同分异构体的分离。4、借助电喷雾质谱、红外光谱、核磁共振、扫描电镜对包合物进行了结构表征。由实验结果和计算软件模拟得出同分异构体包合物的最优化构型,表明同分异构体母体上的亲水取代基越多,基团越大,越容易接近亲水性的环糊精空腔外壳,形成氢键作用,增加主客体疏水基团的结合机会。提示:五环三萜中这类同分异构体的分离随其母体上取代基亲水性的增强,β-环糊精和亲水性β-环糊精衍生物的分离能力增强。更多还原

【Abstract】 There are many oleanane and ursane pentacyclic triterpenoids in nature plants. And the isomers often exist together in many nature products. There has no much difference in their structure, which results in similar physicochemical property. Using traditional separation and analysis methods couldn’t reach satisfactory resolution. Great efforts are needed to improve the resolution of the isomers.This paper was focused on supramolecular coordination chromatography technology to resolve this problem. Based on supramolecular coordination chromatography theory, this paper chose appropriate coordination agents by chemical calculation. The separation methods for three isomers were established, which differ in hydrophilic property. The rule of the isomers was summarized by the analysis of separation mechanism. Main research finding are as follows:1、Based on models of the molecular structures and sizes of the isomers and cyclodextrins which are imitated by the software of ChemBioOffice 2005 and Pymol Version 0.99 and the computing of the energy change of the supramolecular system before and after the inclusion process by he rusults of MM,β-cyclodextrin and its derivatives were chose as the appropriate coordination agents to separate the isomers.2、Isolation methods of three chosen isomers was accomplished by coordination chromatography usingβ-cyclodextrin and its derivatives as coordination agents. The resolution was compared while usingβ-cyclodextrin or glucose-β-cyclodextrin as mobile phase additive. The result was: madecassoside and asiaticoside-B （3.08. 4.65） > madecassic acid and terminolic acid （2.02, 2.65） > ursolic acid and oleanolic acid; As for madecassoside and asiaticoside-B、madecassic acid and terminolic acid, the capability of isolation is: glucose-β-cyclodextrin >β-cyclodextrin; As for ursolic acid and oleanolic acid, glucose-β-cyclodextrin <β-cyclodextrin. It shows that the resolution of isomers is correlated closely to substitutional group and the difference in hydrophobic group plays an important role in the chromatography separation.3、Using different chromatographic column, the resolution of RpC₁₈ 0.77 is smaller than RpC₈ 1.08. The chromatographic column RpC₈ is favorable for chromatography separation. As not observing molecular ion peak of supramolecular structure in MS, It was inferred that the isomers and cyclodextrin couldn’t form very steady supramolecular structure in the process of the separation. It is confered that the hydrophobic effect plays the important role in the chromatography separation and the cyclodextrin cooperating with chromatographic column resulted in the separation of the isomers.4、The supramolecular structure have been confirmed by MS、IR、NMR、SEM. The optimization host-guest coordination compound simulated by the software based on experiment result and chemical calculation shows that the more substitutional group of isomers is hydrophilic, the more chances the hydrophobic part of isomers touch hydrophobic cavum of cyclodextrin. It is deduced that the capability ofβ-cyclodextrin and its hydrophilic derivatives to separate the isomers enhanced while the hydrophilicity of isomers increasing.更多还原