Research On Extraction And Purification Of Betula Platyphylla Suk Leaf Flavonoids And Its Prevention Of HUVEC Oxidative Damage

Betula platyphylla suk is a common tree species in northeast forest region,which is with advantages of extensive distribution and strong adaptability etc.The leaf of betula platyphylla suk contains rich active substances,such as flavonoids and phenolic acids etc.Bark of betula platyphylla suk can be made into paper and can also be made into medicine,which is with the functions of relieving cough and asthma.Juice of betula platyphylla suk can be made into beverage,which can improve immunity of people and supplement various kinds of nutrition.This experiment takes leaves of betula platyphylla suk to extract betula platyphylla suk leaf flavonoids and then studies antioxidant activity.First,ultrasonic extraction technology has been adopted to extract betula platyphylla suk leaf flavonoids and response surface optimization method has been applied to optimize flavonoids extraction conditions.Second,NKA-9 macroporous adsorption resin has been selected to purify the extracted flavones extract;dynamic adsorption text and static adsorption test have been adopted to optimize purification condition.Third,antioxidant capacity of purified betula platyphylla suk leaf flavonoids extract has been verified through removing DPPH free radical,hydroxyl radical,ABTS radical and reduction ability test.Fourth,test cultivates SOD activity,GSH-PX activity and T-AOC total antioxidant capacity in human umbilical vein endothelial cells(HUVEC)and verify if betula platyphylla suk leaf flavonoids extract can prevent cell oxidative damage.Experimental results are as following:1.The optimal extraction process parameters have been confirmed: extraction should be made with material liquid ratio at 1:41,ethanol mass fraction at 90% and ultrasonic time at 44 min,the highest flavonoid yield rate is 6.12%;2.The optimal process parameters for NKA-9 macroporous adsorption resin purifying betula platyphylla suk leaf flavonoids extract are: sample concentration at 0.8mg/ml,sample amount at 3BV,sample rate at 1.5ml/min,PH value at 3,eluent volume fraction at 90% and eluent dosage at 3BV;flavonoids content in the extract attained under this condition can reach 68.5%.3.When the concentration of betula platyphylla suk leaf flavonoids extract is 0.20mg/mL,the DPPH free radical scavenging rate is 86.89%;when the concentration is 0.18mg/mL,ABTS free radical scavenging rate is 96.26%;then the dosage of flavonoids extract is 1.9mg/mL,hydroxyl radical savenging rate is 71.18%.4.When the concentration of betula platyphylla suk leaf flavonoids extract is 10?g/mL,the SOD activity,GSH-PX activity of the cell can be strengthened significantly,the level of reactive oxygen species in cell can be improved(p<0.01).Experimental results have shown that betula platyphylla suk leaf flavonoids extract is with obvious anti-free radical function and can prevent the cellular oxidative damage.