Extraction, Islation, Structural Modification Of Puerarin From Pueraria Lobata

Puerarin(4',7-dihydroxy-8-D-gluco-isoflavone) is one of important active components of pueraria lobato(Wild.) Ohwi, Pharmacological experiments showed that it had many effects to reduce blood vessel resistance,improve circulation of brain and coronary artery,reduce the quantum of oxygen consumed by cardiac muscle. Moreover,it had the advantages of little toxicity and quick metabolizability. However, the imperfect method of extraction and its bad solubility in fat solvent or water caused by its structure of isoflavone result in poor bio-utilization ratio which restrict its bio-activity and clinic application. To solve the problem mentioned above and enhance the activities of puerarin, the experiment extracted and isolated puerarin from pueraria lobato(Willd) Ohwi and modified it with chemical methods.Pueraria lobata(wild.)ohwi was warming soaked in the Ethanol. Then the Eththanol solution was condensed to the ointment, which was dissolved by n-butanel. The solution of n-butanel was separated by water and light petroleum respectively. Disappearing of puerarin fluorescence part on TLC(thin layer chromatography) was regarded as the end of warming soak and separation. The light petroleum separated solution was decolored on Al2O3 column, low pressure condensed, filtered, dried, dissolved and crystaled. After that, the high pure objective compound was obtained. However, its bio-utilization ratio is not good due to its poor solubility in fat solvent or water. To solve the problem and enhance the activities of puerarin,its structure was modified by chemical methods. A series of derivatives were gained, the structure of puerarin and its derivatives were identified with infrared (IR) and nuclear magnetic resonance (NMR) spectrometers. Purity and yield were determined respectively with ultraviolet(UV)spectrometers.The significant findings in the experiment include: 1. Selected the method of warming soak and separation in two kinds solvent, ended the soak and separation when the fluorescence part on TLC(thin layer chromatography)disappeared. The yield and purity of puerarin were 1.41％and 97％ respectively. 2. The blue fluorescence spot on TLC was the sign of puerarin. Choose methanol -chloroform (4:1)as extending solvent , Its Rf was 0.31. The data of nuclear magnetic resonance hydrogen spectrum accorded with characteristic of puerarin structure. The peak of H-1″in Glucose group is puerarin characteristic peak.3.Eight derivatives were obtained with the chemical method,the structure of eight derivatives was identified by infrared (IR) and nuclear magnetic resonance (NMR) spectrometers.It was showed that six new derivatives included 3′-methylene- dimethy-lamine-puerarin, 3′,5′-methylene-diethylamine-puerarin,3′-methylenemorpho line-puerarin,3′-methylene-N-methylpiprrazine-puerarin,3′-methylene-hexahydropyridine-puerarin and 3′-methylene- pyrolipinum-puerarin, two known derivatives were 4′,7-Di-O-hydroxyethyl- puerarin and hexa-O-puerarin.