Study On Esters Synthesis Of Ginsenoside Compound K

In the research on Ginseng, the problem about the metabolic reactions of Ginsenosides in animals already became a important research direction of many scholars. Protopanaxadiol and protopanaxatriol as main Ginsenosides in Ginseng, with different metabolic ways in the stomaches and the intestinals, were administrated orally or injected intravenously, and then metabolized mainly compound K(M1) (20-O-β-D-pyranylglucosyl-20(S)- protopanaxadiol). After the oral administration or intravenous injection of Ml, Ml was accumulated in liver selectively and was excreted by the bile, the other was transformed into corresponding fatty acid ester EM1. In a recent study, the researchers examined the antitumor activity of EM1 in comparision with M1 and discovered that EM1 possessed more antimour activity. At the same time, the experimental result also indicated that the toxicity of EM1 was lower and the retention time in the liver was longer than M1, whats more, the results also showed that EM1 has more effective antitumor activity and functions via the activation of immune responses compared with M1. As a result lengthened the existence in the body of human, EM1 has more antitumor activity, and the mechanism of antitumor activity of EM1 was thyough functions via the activation of immune response. At present, researchers, both at home and abroad, get M1, especially EM1 from the metabolite of intestine or samples from animal's blood and liver after oral administration treatment, since the complicated method, difficult extraction, low yield rate etc,only a series of mixtures and functions of EM1 needed to be studied.Ginsenosides can be decomposed by intestinal bacterium and produced new compounds. Based on this latest scientific research and development, according to the metabolic mechanism of intestinal bacterium to ginsenosides, this experiment simulated the palmitic acid etherification of metabolite M1 in vitro, researched the synthesis of M1 and palmitoyl chloride. Two monomers were acquired, one is PM1, the other was named as P1M1 temporarily. According to special proportion, M1 and palmitoyl chloride were mixed and stired over night in the conditions of EtOAc as medium, NaHCO₃ satured with water that is apt to the positive reaction and ice-water bath. EtoAc section was dissolved in MeOH, then the white power mixture was obtained. By the thin layer silical gel columnchromatogragh, as gradient mobile phase including CHCL₃CHCL₃-MeOH(20:1), CHCL₃-Me0H(15:1) and CHCL₃-MeOH(10:1), CHCL₃-MeOH (15:1) and CHCL₃-MeOH(20.1) sections were collected, compound â…  and â…¡ were acquiried by HPLC RP-C18.On the basis of chemical and spectrum (MS and MNR) analysis, compound â…  was eluciated as palmitic acid ester of Ml which palmitic acid and CH₂OH of glucosyl of Compound K formed by dehydration and named as PM1. By the conventional chemical and NMR analysis ,compund â…¡ was conformed as palmitic acid ester of M1.There is further research on that esterfunction of palmitic acid connected with which of C-2 and C-3 of glucose in M1.RP-HPLC was used to determinate the content of PMl in the synthetic compounds. Chromatograghy system as follows: The analytical column was ODS HYPERSIL C18(100x 4.6mm 5u.m) 799160D-554.The mobile phase was 100%MeOH. The flow rate was O.lmL/min and the UV detection wavelength was at 215nm. Column temperature is room temperature. Analytic time was 65 min. Retention time of PMl was 45 min or so. The results showed that the average transformation rate of PMl was 27.59%.Two ways were used to purify semifinished compound K, One was ODS column Chromatograghy, the other was re-crystallization of MeOH. Area unification of HPLC was applied to determine the purification of crystals obtained by two above-mentioned ways. The results showed that re-crystallization of MeOH is simple, saving labour-time, and that the purification of compound k is up to 98.73%.Domestic scholars already carried out the research on the synthesis of fatty acid single ester of Ml (SMI). The pharmacological experiment that SMI acted on Hepa and MFC showed : SMI was a active component of high-efficiency and low-toxicity, however, the transformation rate of it was only 7.94%, the one of PMl as by-product was3.35%.Nowadays, a great of Ml obtained by enzymlization, can be satisfied with the needs of industrial manufacture, however, the transformation rate from Ml to SMI was not high, SMI cant meet the needs of industrial manufacture. PMl and SMI were homologue.In respect to the structure, there were more two carbon in SMI than PMl, P1M1 and Ml were isomer, therefore,above-mentioned compounds should possess the same pharmacological role, this should be verified by the further pharmacological experiment. In this research, a lot of PMl was acquiried in new synthetic material and ways, and the average transformation rate of PMl was 27.59%. The extensive choice of active components, further improvement on synthetic methods, simplification of operating programe and increase in the transformation rate will accelerate the industial manufature of PMl. This research laied a solid theorical foundation on study and exploration new antitumor medicine of ginsenosides.