Studies On Methylation Of Ginenoside Rg₂

Ginsenoside Rg₂ is a kind of protopanaxatrio saponin,which has many pharmacodynamic effects.The study shows that the hydroxyl of ginsenoside has the significant effect on its pharmacological activity.The pharmacological activity and application of ginsenoside Rg₂ have been reported in many studies,but the structure-activity relationship of ginsenoside Rg₂ is not clear.In order to promote the development and utilization of ginsenosides Rg₂,we tried to modify Rg₂ with the methylation methods to make methylated derivatives,lower polarity of molecular structure,provide material foundation to study the structure-activity relationship.The research results are as follows:1.Four classical methylation methods were used to modify the structure of ginsenoside Rg₂.TLC was used to analyze and compare the methylation products obtained by several methods.Among them,the Hakomori method wasted the shorter time,producted the fewer species of ginsenoside Rg₂ methylation derivatives,and the pure ginsenoside Rg₂ methylation modification was more easily to separated product.2.Through the single factor experiment,the factors affecting the acetylation were optimized,including material ratio,solvent,reaction time,temperature,catalyst and so on,and the optimum reaction conditions were obtained.The results show that in DMSO solvent,with DBU as the reaction catalyst,the ratio of Rg₂ to CH₃I is the methylation product obtained at 25 ^oC reaction 30 min at 1:50.The derivative of the product is less and the pure compounds are more easily separated.3.By silica gel column chromatography,separate and purify methylation products,through the EI-MS,¹³C NMR analysis showed that the production is 8 substituted product,namely C-3,C-12,C-3',C-4',C-6',C-2'',C-3”,C-4''replaced,the product is 8 methylated ginseng saponin Rg₂?Rg₂-M?,the yield was 14.4%,the purity of 96.7%.To sum up,we optimizes the ginseng saponin Rg2 methylation method and conditions,methods and conditions of the preparation was studied using 8 methylated Rg₂ ginsenosides,and purification of product purity higher than 96%Rg2-m.Compared with ginsenoside Rg2,the polarity of Rg₂-M is significantly decreased,which can be used to study the structure-activity relationship of ginsenoside Rg₂,providing reference materials for the development and utilization of ginsenoside Rg₂.