Extraction,Isolation and Antioxidant Activity of Flavonoids from Tartary Buckwheat

In this study orthogonal tests were applied to optimize the extraction conditions of flavonoids from tartary buckwheat,including extraction time,ethanol concentration,ratio of sample to solvent and extraction temperature. The optimal extraction conditions are:extraction time 5 hours,ethanol concentration 70%,ratio of sample to solvent 1:15 and extraction temperature 70℃. After purification,the flavonoids extracted from tartary buckwheat with the purity of 73.32% were obtained. Antioxidant activities of flavonoids of tartary buckwheat,ethanol extract of tartary buckwheat powder,and ethanol extract of tartary buckwheat hull were studied at different concentrations and pH values and compared with those of rutin and vitamin C. Results suggested that the antioxidant activity of flavonoids of tartary buckwheat is lower than that of vitamin C,but stronger than that of rutin or the ethanol extract of tartary buckwheat powder,and much higher than that of the ethanol extract of tartary buckwheat hull,and the scavenging capability on DPPH free radical increases with is concentration increasing. When pH is in the scope of 2 to 8,the scavenging capability on DPPH free radical firstly increases and then decreases,which is the lowest at pH 7.