Analysis Of Oleanane And Ursane Pentacyclic Triterpenoids By Supramolecular Coordination Chromatography

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.