Extraction And Purification Of Polyphenols From Rhamnus Utilis Leaves And Analysis Of Antioxidant Activity

Rhamnus utilis is belongs to Rhamniaceaea,it is known as a medicinal plant in some areas of China.In this paper,the extraction and purification technology and antioxidant activity of polyphenols from the leaves of R.utilis.Firstly,ultrasonic and microwave assisted extraction were used to extract polyphenols and optimized extraction process.Secondly,purification of crude polyphenols from R.utilis leaves with macroporous resinthe and determined the optimum purification parameters.Finally,the antioxidant activity was evaluated.The purpose of this study is to provide the basis for the further development of this plant resource..The main findings are as follows:1.Used ultrasonic and microwave assisted extractionthe to extract the polyphenols from R.utilis leaves.Studied the effects of solvent volume fraction,liquid-material ratio,extraction time and temperature on the extraction of polyphenols and response surface methodology was designed based on single factor experiment.The results showed that the best conditions of ultrasonic extraction wsa as follows: ethanol volume fraction was 60 %,extraction time was 40 min,liquid-material ratio was 10:1(m L/g),extraction temperature was 65 ℃.Under these conditions,the measured polyphenol extraction amount was 57.73 mg/g.The optimum conditions of microwave assisted extraction were as follows: ethanol volume fraction was80%,extraction time was 5.5 min,liquid-solid ratio was 20:1(m L/g).Under these conditions,the actual extraction amount of polyphenols was 47.51 mg/g.Both of them were closed to the theoretical prediction.Compared ultrasonic assisted extraction with microwave assisted extraction,the ultrasonic assisted extraction method was more better.2.Four macroporous resins AB-8,D101,NAK-9,and HPD600 were screened by static and dynamic adsorption experiments,and D101 was determined to be the best adsorption resin.The study showed that the best process for purifying polyphenols was as follows: the sample solution concentration was 0.4 mg/m L,the pH of sample solution was 5.0,the sample liquid flow rate was 1.8 m L/min,the integral number of desorption solution was 85%,and the flow rate of desorption solution was 1.2 m L/min.Under these conditions,the recovery rate of polyphenols reached 89.33%.3.The total reducing ability,DPPH radical scavenging ability and hydroxyl radical scavenging ability of crude polyphenols and purified polyphenols extracted by the two extraction methods were studied and compared respectively.The results show that the R.utilis leaves polyphenols have certain antioxidant activity,and the hydroxyl radical scavenging ability of R.utilis leaves polyphenols in the concentration range of0.025～0.15mg/m L is even higher than that of VC at the same concentration.