Study On Extraction,Purification And Antioxidant Activity Of Rhamnus Davurica Pall Polyphenol

Rhamnus davurica Pall is a common wild plant resource in Changbai Mountains and Great Khingan Ranges of Northeast China.It tastes bitter and most of Rhamnus davurica Pall fruits were wasted when they were ripe.Rhamnus davurica Pall fruits are rich in polyphenols and have higher polyphenols content than other fruits and vegetables.Polyphenols have remarkable antioxidant,anti-cancer and free radical scavenging effects,which are closely related to the health of modern people.However,due to the origin limitation,the fruit storage difficulty during transportation,and the foreseeable loss of polyphenols activity,etc.How to extract and purify polyphenols from Rhamnus davurica Pall is of great importance.In this experiment,wild Rhamnus davurica Pall picked in the Great Khingan Range were used as raw materials.The ultrasonic assisted extraction method was optimized by response surface method,which is based on single factor experiment.We chose the best purification method through comparing the adsorption and desorption properties of different macroporous resins.The antioxidant activity of polyphenols was evaluated through in vivo and in vitro experiments,providing a reference principle for the research and processing of functional foods with polyphenols from Rhamnus davurica Pall.The main research conclusions are as follows:(1)The optimum conditions of ultrasonic-assisted extraction of polyphenols from Rhamnus davurica Pall.Based on the single single factor experiments,the liquid-material ratio,extraction solvent concentration,ultrasonic power and ultrasonic time were selected as variables and the amount of polyphenol extracted was the response value.The ultrasonic assisted extraction of polyphenols from Rhamnus davurica Pall was optimized by response surface experiments with four factors and three levels.The extraction process conditions after optimization are as follows: the liquid-material ratio of 15:1,extraction solvent concentration 52%,ultrasonic power 550 W,ultrasonic time 43 minutes,the extraction amount of polyphenol(6.23±0.18)mg/g.(2)The selection of macroporous resin and determination of the optimum purification conditions.Three different types of resins were selected to screen out the resins with the best purification effect for polyphenols from Rhamnus davurica Pall and then the static and dynamic adsorbation-desorption was performed.The results showed that the adsorption and desorption capacity of AB-8 macroporous resin was better,and the purification conditions were optimized.Isothermal adsorption experimental shows that AB-8 macroporous resin on polyphenols from Rhamnus davurica Pall was exothermic.The adsorption process conforms to Langmuir isothermal adsorption model and Freundlich isothermal adsorption model and the fitting degree is better.The optimum conditions for purification of polyphenols from Rhamnus davurica Pall by AB-8 macroporous resin were as follows: the mass concentration of column liquid 7.07mg/mL,adsorption time 4 hours,desorption time was 2 hours,sample pH 4,70% ethanol as the desorption solvent,adsorption velocity of the upper column was 2BV/h,desorption velocity of the eluent was 2BV/h.Under these conditions,the purity of polyphenols increased from 11.28% to 73.79%,the black-purple powder obtained by freeze-drying was polyphenol extract from Rhamnus davurica Pall.(3)Evaluation of antioxidant activity of polyphenols from Rhamnus davurica Pall in vitro.After purification of Rhamnus davurica Pall polyphenols sample,the total reducing power,the scavenging effect of hydroxyl radicals on OH,ABTS and DPPH free radical scavenging capacity were determined.Vitamin C(Vc)was used as reference substance for comparison.The results showed that there was a positive correlation between the concentration of polyphenols and antioxidant capacity in the four antioxidant systems.When the concentration of Vitamin C and polyphenol solution of Rhamnus davurica Pall was 0.5mg/ml,DPPH free radical scavenging rate of polyphenols in Rhamnus davurica Pall was 74.28%,DPPH free radical scavenging rate of Vitamin C was 98.82,DPPH free radical scavenging rate of polyphenols in Rhamnus davurica Pall was 75.17% of Vitamin C;when the solution concentration was 1.0mg/mL,ABTS free radical scavenging rates of polyphenols and Vitamin C were 96.51% and 98.88%,the results were similar;when the solution concentration was 0.5mg/L,·OH hydroxyl radicals scavenging rates of polyphenols and Vitamin C were 95.36% and 28.91%;when the solution concentration was 1.0mg/mL,the reducing power of polyphenols(0.701)was 38.39% of Vitamin C(1.826).It has better scavenging effect in four kinds of antioxidant systems,but its antioxidant capacity is still weaker than Vitamin C.(4)Study on antioxidant activity of polyphenols from Rhamnus davurica Pall in miceTo evaluate the antioxidant activity of Rhamnus davurica Pall polyphenols on acute ethanol-induced oxidative damage in mice,Rhamnus davurica Pall polyphenols were fed to mice meanwhile determinating the SOD activity,MDA content,CAT activity,GSH-PX activity in the liver to determine the antioxidant capacity of polyphenols extracts.The results showed that the polyphenols extract from Rhamnus davurica Pall could effectively improve the antioxidant capacity of ethanol-induced acute injury mice.