Extraction,Purification And Functionality Of Total Flavonoids From Leaves Of Fagopyrum Tataricum(L.) Gaerth

This paper explored the extraction and purification process,antioxidant activity in vitro of flavonoids from blooming tartary buckwheat leaves.Flavonoids extracts were given gavage to ?-type diabetes mellitus mice which were induced by high suger and fat diet combined STZ in order to investigate its antioxidant activity in vivo,the effects of glucolipid metabolism and protection on liver,kidney,spleen and islet tissue.It aimed to provide theoretical basis for the development and utilization of flavonoids in buckwheat leaves.The mian research results were as follows:The flavonoid compounds with blooming buckwheat leaves were extracted by ultrasonic assisted method.It investigated the effects of ethanol concentration,extraction temperature,solid-liquid ratio,extraction time and ultrasonic power on flavonoids yield by single factor experiment.Then,Box-Behnken response surface methodology of four factors and three levels by Design Expert 8.0.5.0 was used to optimize the extraction process.The optimal extraction conditions were as follows:ethanol concentration was 60%;extraction temperature was 72 ?;material ratio was 1:32;ultrasonic assisted time was 31 min;and ultrasonic power was 101 W.Under these conditions,the extraction yield of flavonoid was 10.25%.Through the study of adsorption and desorption properties of five tested resin(AB-8,S-8,D-101,HPD-600,DA-201),it showed that AB-8 macroporous adsorption resin which was the ideal resin for the purification of flavonoids from buckwheat leaves had higher adsorption rate and adsorption capacity,and was easy to desorption.The optimum purification process were as follows:the pH of the sample solution was 5,concentration was 1.50 mg/mL,flow rate was 1.00 mL/min,loading quantity of sample was 33mL/g resin,the eluent was 75%ethanol,the pH of eluent was 5,flow rate was 1.50 mL/min,the amount of eluent was 10 mL/g resin.The recovery rate of flavonoids in tartary buckwheat leaves was 77.01%,and the purity of flavonoids was 90.6%,which was 3.02 times of that before purification.The antioxidant activity of total flavonoids in tartary buckwheat leaves was analyzed by using Vc as contrast.The results showed that the total flavonoids of tartary buckwheat leaves had high antioxidant activity and ability to scavenge · OH and O2-.When flavonoid concentration was 0.7mg/mL,the clearance rate of · OH and O2-was 95%.The ability of scavenging · OH and O2-was stronger than Vc in a certain concentration range.In addition,the scavenging ability of the flavonoids on NO2-was better than Vc at the same concentration,the reducing power was close to Vc,and the scavenging ability of DPPH was weaker than Vc.Flavonoids extracts were given gavage to II-type diabetes mellitus mice which were induced by high suger and fat diet combined STZ.The results showed that flavonoids extracts could reduce the apoptotic rate of islet cell,improve the content of serum insulin,increase the activity of T-SOD and GSH-PX in serum,liver,kidney and spleen,decrease the content of MDA,improve the glucose metabolism disorder in mice,decrease the content of serum TC and TG,increase the content of HDL-C,improve the lipid metabolism of diabetic mice;reduce lesion damage of liver,kidney,spleen and islet tissue.