Purification Of Flavonoids From The Fruits Of Rhamnus Utilis And Analysis Of Antioxidant Activity

Rhamnus utilis is a kind of green bush or small tree.It belongs to Rhamnaceae.Its fruits have functions of clearing away heat and toxic materials,making diarrhea and killing insects,relieving cough and resolving phlegm.In some regions of our country,its fruits and leaves are used for aiding digestion,relieving alcoholism,protecting liver,decreasing enzyme,killing virus,etc.In the middle and later periods of 20 th century,scholars made intensive study into chemical components and pharmacologic action of multiple plants in Rhamnus,but there are rare reports about R.utilis.Because there is no relevant research,R.utilis has not been widely used as a drug.This study made an analysis on purification and antioxidant activity of R.utilis fruits.Response surface methodology optimizing was carried out on ultrasonic-assisted extraction technology for flavonoids in R.utilis fruits to achieve the maximum extraction amount of flavonoids.Macroporous adsorption resins were used to purify ethanol crude extract and determine the optimum purification technological parameter.Finally,its antioxidant activity was evaluated.This study is to provide theoretical evidence for the development of this plant in new type drugs and health care products.The main research contents and results are as follows:(1)Response surface analysis(RSA)method was used to optimize ultrasonic assisted extraction technology of flavonoids in its fruits.On the basis of four single factor testing including liquid-to-solid ratio,ethanol concentration,extraction time and extraction temperature,the optimal process parameters of ultrasonic assisted extraction of flavonoids in its fruits were determined.The results showed that the optimization of extraction process was30 mL/g,ethanol concentration 50%,extraction temperature 22?,extraction time 50 min.On this condition,the extraction amount of flavonoids in its fruits can reach 60.36 mg/g,which is basically consistent with the theoretical value,60.25 mg/g.(2)Macroporous absorption resin HPD100 was selected as the most proper one for purifying flavonoids of its fruits.The optimal purification process parameters are as follows: loading buffer quality concentration0.3 mg/mL,loading buffer p H 2-3,sampling flow rate 2 mL/min,loading buffer volume 40 mL,washing water quantity 3 BV,eluent concentration80% ethanol solution,elution speed 2 mL/min and stripping liquid amount40 mL.The average recovery rate of flavonoids from its fruits that are purified by macroporous absorption resin HPD100 is as high as 94.23%.(3)Prussian blue method and DPPH radicals scavenging experiment were used to detect the overall antioxidant activity of its fruits flavonoids aqueous solution.The results showed that: the reducing ability of flavonoids aqueous solution in its fruits was evidently higher than the reducing ability of vitamin C,indicating that the flavonoids in its fruits has a stronger antioxidant capacity.