Study On Isolation,Purification And Antioxidation Activity Of Flavonoids From Lycium Ruthenicum Leaves

Lycium ruthenicum Murr.is an important medicine and food homologous plant in desert areas of China.It belongs to a perennial shrub of the genus Solanaceae.There are some flavonoids in the Lycium Ruthenicum Leaves.It is the main active ingredient in the development of anti-cardio-cerebrovascular drugs.Because it has a certain degree of anti-oxidation.In this paper,the flavonoids were subjected to extraction,Isolation and purification process optimization,antioxidant activity research for different flavonoids.The main conclusions were as follows:(1)The ultrasonic-microwave synergy extraction process of total flavonoids from Lycium ruthenicum leaves was optimized by response surface methodology.By means of the microwave power,liquid to solid ratio,extraction time and ethanol concentration of four factors,primary and secondary relations of:liquid to solid ratio>ethanol concentration>extraction time >the microwave power.The results indicated that the optimal extraction conditions were determined as follows:the microwave power of 175 W,liquid to solid ratio of 18.9 mL/g,extraction time of 9.9 min and ethanol concentration of 69%.Under the above conditions,extraction rate of total flavonoids could reach(0.997±0.015)%.(2)AB-8 macroporous resin was used to further purify the flavonoids extracted from the Lycium Ruthenicum Leaves.By means of the concentration of sample soultion,pH of sample soultion and velocity of sample soultion of three factors.The effects of various factors on the adsorption rate of total flavonoids:concentration > pH > velocity.The optimal adsorption condition is the sample concentration was 1.0 mg/mL,the sample solution pH was 5.0,the velocity of sample soultion was 1 mL/min.By means of ethanol concentration,velocity of eluent flow and eluent volume flow of three factors.The effects of various factors on the desorption rate of total flavonoids:ethanol concentration > eluent volume flow > velocity.The optimal desorption condition is the ethanol concentration was90 %,the velocity of eluent flow was 1 mL/min,the eluent volume flow was 6 BV.The average recovery was(76.74±1.47)%.(3)The purified flavonoids was further isolated into four components by Sephadex LH-20 column chromatography.Through ultraviolet detection and UPLC qualitative analysis,four components were identified as Rutin,Quercetin,Luteolin and Isorhamnetin,and their respective contents were 0.92 %,0.08 %,0.79 %,0.84 %.(4)The antioxidant activity of different flavonoids from the Lycium Ruthenicum Leaves in vitro was evaluated by five factors: determination of total antioxidant capacity,scavenging effects of DPPH free radical,ABTS free radical and super-oxide anion,and lipid peroxidation inhibition rate in lipid peroxide system.The results showed that concentration and antioxidant properties of each components are show a certain linear relationship,and the antioxidant capacity increases with the concentration of varying degrees of increase.Quercetin and Rutin showed strong antioxidant properties,which may be related to the amount and substitution position of phenolic hydroxyl groups in their structures.