Isolation And Purification Of Flavonoids From Exochorda Racemosa And Biologycal Activity

The objective of this research was to optimize the extraction process of flavone from Exochorda racemosa using microwave. The flavone was extracted, isolated and identified; in vitro antioxidant activity were also measured. At the same time, three flavonoids were proved to have function of lowering blood sugar.(1) Response surface methodology(RSM) was used to optimize the flavonoids extraction from Exochorda racemosa using microwave based on the Box-Behnken design. The power, microwave time, solid / liquid ratio, temperatures were analyzed as variables. The results showed that both power and extraction time had significant effects on yield of polysaccharide. The optimal conditions were as follows: power 357 W, ratio of solid to liquid 1:26 g/m L, extraction time 63 min. Under this condition, the yield of flavonoids was 14.59 mg/g, compared with theoretical value, which was 14.67 mg/g, the relative error was 0.5%.(2) Ethanol, petroleum ether, ethyl acetate, butyl alcohol ware used to extract flavone from Exochorda racemosa. Column Chromatography and HPLC were used for separation and purification. MS and NMR were used to identify the chemical composition. Three compounds were isolated and were identified as Apigenin, Apigenin-7-O-β-D-glucopyranoside and rutin.(3) By comparing with ethanol, petroleum ether and water, the in vitro antioxidant activity of ethyl acetate was the highest one. in vitro antioxidant activity were measured. The scavenging effects on DPPH radica, hydroxyl radica L(.OH), superoxide radica(O2-)were determined. The value of IC50 of DPPH·, OH·, and O2-· were 0.52,0.55,1.18 mg/m L. The scavenging effect of DPPH·、OH· was higher than BHT, but lower than VC.the scavenging effcct of O2-·were lower than VC and BHT.(4) In order to reveal the mechanism and components of flavonoids in Exochorda racemosa to lower blood sugar. The hypoglycemic functions of apigenin, apigenin-7-O-β-D-glucopyranoside and rutin were tested respectively. The results showed that the α-glycosidase inhibitory activities of apigenin, rutin were higher than acarbose, apigenin-7-O-β-D-glucopyranoside was lower than acarbose.