The Chemical Stability Of Cichoric Acid And Separation And Analysis Of Its Epimers By High Performance Liquid Chromatography

Echinacea purpurea is a native north American plant which belongs to Echinacea.it is the best-selling phytomedicine commonly treated as immunostimulant and immunomodulation.Caffeic acid derivatives, polysaccharide,glycoprotein,alkamide are the main relevant constituents. The cichoric acid is the most important active compound,which can inhibit HIV and HIV integrase,also has anti-inflammatory,anti-virus, anti-cancer,anti-fungal effect.So it is the focus of research.In this thesis, the chemical stability and HPLC analysis of cichoric acid epimers was studied,the main contents are as followed:1.The stability of cichoric acid in the solution and solid state was studied,respectively.With the analysis of High performance liquid chromatography-Mass spectrometry and TG-DSC experiment,the results demonstrated that cichoric acid in the solid state is very stable,even though heated at the temperature 105℃.Whereas cichoric acid in the aqueous solution become relatively unstable,it was hydrolyzed into caftaric acid and caffeic acid first,finally only caffeic acid was detected in product.In addition,cichoric acid in methanol can keep stable,too.2.The photoepimerization of L-cichoric acid was investigated.When the solution of L-cichoric acid was irradiated with the UV light, L-cichoric acid was converted to another compound partially.With the separation and identification by HPLC-MS,UV spectrum,optical rotation, and ~1HNMR,the results demonstrated that L-cichoric acid could partially be epimerized to meso-cichoric acid.The rates of epimerization of L-cichoric acid in different solvents had significant differences.At 365 nm,the ratio of epimerization at the equilibrium state is ordered as follows:acetonitrile＞methanol＞tetrahydrofuran＞water;While at 254 nm, the order is:acetonitrile＞tetrahydrofuran＞methanol＞water.In addition, the ratio of epimerization at 254nm is more than that at 365nm.3.A HPLC method was developed to analyze the L-cichoric acid and its epimer.Epimers were separated by HPLC using Spherigel C18(5μm, 200×4.6mm)as the column,A(0.1%formic acid +0.1%TEA +water):B(acetonitrile)=85:15 as the mobile phase.Meanwhile,the flow rate was 1mL/min,temperature of column were set at 25℃.This method can be applied to qualitative and quantitative analysis for cichoric acid epimers in Echinacea purpurea.