Purification Of Dihydromyricetin From Tengcha And Preliminary Study On Its Metallic Complexes

Tengcha(Ampelopsis grossedentata W.T.Wang),belongs to Ampelopsis Michx of Vitaceae.It is grown abroad in the south of the Yangtze River.It's used for drinking and drug among the people,which contains rich flavones,such as Dihydromyricetin(DMY for short).The tender stems and leaves of Tengcha have been made into a healthy drink which is called "mystic tea" for treating rheum,fever,gall of fauces,hepatitis and so on, with a long history of several hundred years among Yao and Zhuang nationality in China. The studies on Tengcha were mainly in isolation and identification of active component and functional activity of flavonoids.Purification of dihydromycetin from Tengcha and a preliminary study of metallic complexes were studied in this paper.1 Optimal purification process of dihydromyricetin from TengchaHigh purity dihydromyricetin was obtained with water recrystallization,the yield was34.59%after the third repetition and the purity was above 90%.Experiments of 11 kinds of macroporous adsorbing resins adsorbing and desorbing dihydromyricetin indicated that No.1 was one of the most appropriate resins in all for preliminary purification of flavones.Its adsorbing capacities were 36.06mg/g,desorbing rate were 86.17%.In column of No.1,the optimum conditions were that the concentration of crude flavones was 6-7mg/ml,the volume of sample was 1/3 that of column,flowing velocity was 1.8ml/min,eluting solution was 80%ethanol,which led to 65%purity of the dihydromyricetin and 80%desorbing rate of dihydromyricetin.It's a better way to purify dihydromyricetin through polyamide column with crude flavonoid powder pretreatment. The suitable parameters were:eluting solution 60%ethanol,flown rate 0.6ml/min,the weight of sample 0.5g.The desorbing rate was 86%and the purity reached 85%.2 Preliminary study on metallic complexes of dihydromyricetinThe coordination reactions between the product of water repetition and calcium ion, zinc ion,ferrous ion were researched with different molar ratio under the alkaline condition.Through the UV- spectrum and IR spectrum,it was confirmed that the coordination reactions had happened.As far as antioxidant activity,the scavenging capability to hydroxyl radical of zinc complex and calcium complex were significant,the clearance rate over 80%.The clearance rate of ferrous complex was low,less than 20%.