Study On The Establishment Of Alkali Extraction And Acid Precipitation Method And Stability In Different Methods Of Silymarin

The purpose of this study is to solve the problem that organic solvent is used in large quantities, harmful solvent residue and energy consume in the preparation of silymarin. In this dissertation, in order to gain a green and safe method, influencing factors using alkali extraction and acid precipitation to extract and isolate silymarin were investigated and optimized. On the basic of these, strong points and weaknesses of extraction methods including alkali extraction and acid precipitation, microwave-assisted extraction, ultrasonic-assisted extraction, internal reflux method by ethanol, internal reflux method by boiling water and internal reflux method by high-pressure hot water were compared. Alkali extraction and acid precipitation method is green, energy saving and cost saving in despite of dissatisfactory extraction efficiency. Microwave-assisted extraction and ultrasonic-assisted extraction could rise extraction yield efficiently. Internal reflux method by ethanol has high extraction yield while internal reflux method by hot water is green. But both of them are energy comsuming along with silybin decrease. Meanwhile, the stability of silybin in different extraction methods is studied using HPLC-MS. Chemical changes take place on silybin in high temperature. Silybin is sensitive to high temperature and stagnant to solvent polarity and heating methods. Higher the temperature of alkaline water is, faster the change of silybin takes place. The chemical change product is a new isomeric compound of silybin. At the same time, chemical changes take place on silybin in alkaline water and the products are complicated. Higher the concentration and temperature of alkaline water is, faster the change of silybin takes place. But silybin is steady in acid water.