Purification and Structural Analysis of Flavonoids from Lycium barbarum Leaves

In order to determine the best purification process of Lycium barbarum leaves flavone,confirm the structure and contents of the product after purification. Comparing the adsorption and desorption performance of six macro porous adsorption resins including AB-8,DM301,NKA-9,HPD-100,HP-20 and D101,and selecting the best one to research the condition of sample and elution,investigation on pH of sample,concentration of sample,sample flow rate,and the concentration,dosage,flow rate of elution. The composition and structure of the purified compounds were analyzed by UV-Vis,FT-IR and HPLC. The results showed that the D101 macro porous adsorption resin had the best adsorption performance and desorption effect. The optimal purification process was as follows:The concentration of the upper sample was 3.728 mg/mL,the pH of the upper column was 6,and the flow rate of the upper sample was 2 mL/min. The eluent of 70% ethanol was used,the flow rate was 2 mL/min,and the amount of the eluent was 3.5 BV. Under the conditions,the total flavonoid content increased from 355.05 mg/g to 809.89 mg/g with a 2.28 fold increase. The detection for UV-Vis showed that the purified product had the basic structure of flavonoid C6-C3-C6. FT-IR test showed that the multiple characteristic functional groups including C=O,hydroxyl,phenol hydroxyl,methyl and methyl were more prominent than the crude extract. By HPLC,the contents of rutin,chlorogenic acid,quercetin,caffeic acid,p-coumaric acid,kaempferol and ferulic acid in the purified product were 179.45,60.92,3.14,6.35,2.66,2.45 and 1.38 mg/g respectively.