Separation And Purification Of Puerarin From Radix Puerariae

The effective ingredients of natural products are the important raw material of pharmacy. Radix puerariae,a kind of frequently used traditional Chinese medicine, has extensive pharmacological activity. The main ingredient is pueraria flavonoids, which play a major pharmacological effect of puerarin. Puerarin can improve the blood vessel circulation of heat and brain, regulate blood pressure, promote blood circulation, and protect the liver. Especially, it's very effective for cardiovascular diseases.At present, these are many of purification techniques of puerarin which have different advantages and disadvantages, but high yield can not be got. Therefore it is of great interest and significance to explore novel techniques to purify puerarin. In this paper, the common ethanol refluxing method and the new microwave technology will be synthesized. First, the pueraria flavonoid will be extracted by the microwave-assisted method. Then the puerarin derivatives will be hydrolyzed by chlorhydric acid according to the characteristics of the puerarin and its derivatives. Finally, the pure puerarin will be received through extractioin and crystallization under different pH. This study is focused on the extraction process of pueraria flavonoid and the acid hydrolysis process of puerarin derivatives. And the reaction conditions will be optimized to lay a good foundation of the industrial production of puerarin.The microwave assisted ethanol refluxing method is chosen to extract puerarin flavonoids. The technological conditions such as extracting time, extracting temperature, microwave power, extractant concentration and extractant dosage are investigated with the help of single factor experiments and the orthogonal experiments. The optimized process conditions are worked out as follow, extracting time 60 min, extracting temperature 80℃, microwave power 800 W, extractant concentration 80% and solid-liquid ratio 1∶20. And finally the puerarin flavonoids extraction rate and the yield rate is 90.18% and 20.15%, respectively.The acid hydrolysis of the puerarin derivatives by conventional method, ultoasonic assisted method and microwave assisted method have been investigated respectively and optimized through single factor experiment and orthogonal experiments with the content of puerarin as the examinal index. The content of puerarin is added about 58% than which is not acid hydrolysis, under the three acid hydrolysis technique, the reaction time is 120 min by acid hydrolysis method, while reaction time is 45 min by ultrasonic auxiliary, and the reaction time is only 10 min by microwave assisted acid hydrolysis method.On the basis of hydrolysis reactions, the effects of ethyl acetate and butanol as the extractants and the crystallization of different pH are studied to separate and pure puerarin further. The results show that, under the optimized conditions, ethyl acetate is much better than butanol as the extractant. After extracting, the content of puerarin in hydrolyzed layer is 50.69 mg/mL, and the crystallization precipitation of crude products has a best effect when the pH is adjusted to 5-6. The weight of the purified puerarin is 1.465 g, the purity and yield of puerarin is 70.18% and 2.95%, respectively.