Purification Of Puerarin By The Double-injection Crystallization And Its Solubility Determination

The effective ingredients of natural products are the important raw material of pharmacy. Active compounds, especially flavonoids, have been the focus of raw material drug. As the main active component of pueraria flavonoids, puerarin is paid more attention increasingly for it can improve the blood vessel circulation of heart and brain, reduce the oxygen consumption capacity of cardiac muscle, reduce the blood sugar, prevent the hypertension and artery teriosclerosis and so on many kinds of pharmacological action, the pure product is very popular in international market.At present, there are many of purification techniques of puerarin which have different Advantages and disadvantages, but high yield can not be get. Therefore it is of great interest and significance to explore novel techniques to purify puerarin. In this paper, the purification techniques of puerarin are as follows: Coarse puerarin was crystallized by double-injection. Then, acid hydrolyzing process was imported to remove the ramification of pueraria. Emphatically, the condition of the crystal and acid hydrolyzing process were studied and the solubility of puerarin in crystal solvent was determined. The optimal operation parameters were chosen and consequently establish the favorable base for the industrialized production of puerarin. The experimental results indicate that, compared with some other methods purification, both the double-injection crystallization techniques and the acid hydrolyzing techniques have their inimitable traits. Furthermore, the techniques can ensure relative higher yield and purity of product. In order to get high yield, this paper bring forward a reclaim method of puerarin in crystal solution and acid hydrolyzing solution.(1) The coarse puerarin in purity of 45.94% was crystallized by double-injection. The influences of crystal temperature, stirring velocity, crystal time, volume of substrate, ratio of the solventing-out solvent and the soluble solution were investigated in detail to find the optimal crystal techniques. It was found that the yield and purity of puerarin can reach 87.52% and 87.76% respectively, when the temperature is 45℃, the stirring velocity is 60r/min, the volume of substrate is 10mL, the crystal time is 4h, the ratio of the solventing-out solvent and the soluble solution is 0.5.(2) The puerarin in purity of 75.52% after first step crystalization was hydrolyzed by acid. The influences of neutralization by different alkali neutralization, neutralizing to different pH, different washing mode were investigated in detail to find the optimal hydrolyzing techniques. The experimental results indicated that by taking NaOH to pH=4, filtrating, desiccating, washing by mode 1, the yield and purity of puerarin can reach 98.19% and 62.18% respectively.(3) This paper establishes a reclaiming techniques of puerarin in crystal solution and acid hydrolyzing solution by solvent. The reclaiming yield of puerarin can reach 43.17% for the crystal solution and 32.69% for the acid hydrolyzing solution, respectively.