Study On The Extraction,Purification And Biological Activity Of Phenol In Strawberry

Strawberry(Fragaria ananassa Duck)is a perennial herb,which belonging to Rosaceae.Strawberries are fleshy red tender,sweet and sour taste.They are rich in polyphenols,anthocyanins,vitamin C,polysaccharides and other secondary metabolites,which also has strong antioxidant activity.At present,the domestic research on strawberry in China is still in the treatment of fresh fruit,the biological activity of strawberry and physiological function of the research is still in infancy,therefore,we need to develop the further market.prospects of strawberry polyphenols active products.Based on strawberry powder as raw materials,firstly,optimized the extraction process of polyphenols in the strawberry,and the extracted polyphenols were purified and analyze its components;secondly,analyzed the phenolics in vitro antioxidant activity and its antimicrobial activity;finally,further research the polyphenols in Hepg-2 cell growth inhibition.The main research results are as follows:(1)Based on the single factor experiment,Box-Benhnken center combination was used to design the response surface experiment.The results showed that the optimum extraction process of strawberry polyphenol was as follows:1:30 g·mL-1,ultrasonic time 20 min,cellulase addition 0.11 mg·mL-1,temperature 62 ?,and under the optimized conditions,the yield of polyphenols was 22.57 mg·g-1.(2)With a mass concentration of 3 mg·mL-1 of strawberry polyphenols extract(pH2)to 1 mL·min-1 sample velocity on 42 mL,dynamic adsorption resin reach saturation;after 80 mL volume fraction of 50%ethanol,with 1 mL·min-1 flow rate of elution,could clear completely,the desorption rate was 94.37%.After the purification of HPD400 resin,the total phenol concentration of the strawberry polyphenol purified solution was improved remarkably.The total phenol content was about 2.71 times before purification,and the total antioxidant capacity was about 2.88 times before purification.Analysis of the purified polyphenols by HPLC showed that the strawberry contained rich phenolic acids and flavonoids.(3)The removal rate from the same concentration before and after purification was compared with that of Vc in the same concentration,analyzing its in vitro antioxidant.When the sample concentration was 2.8mg·mL-1,the crude polyphenols and purified polyphenols on DPPH free radical clearance rate were 67%and 92.7%respectively,and the activity of O2-· free radicals was 77.62 U·L-1 and 147.39 U·L-1 respectively.When the sample concentration was 1.0 mg·mL-1,the crude polyphenols and purified polyphenols ·OH clearance rates were 59.47%and 80.8%respectively.(4)The antibacterial test of the purified polyphenols was carried out,and the antibacterial activity of the strawberry polyphenols was tested by the filter paper method.The inhibitory ability of the three kinds of bacteria was greatly inhibited by Escherichia coli,Staphylococcus aureus and Salmonella.The minimal inhibitory concentrations of the three strains were Staphylococcus aureus 0.6 mg·mL-1,Escherichia coli 0.8 mg·mL-1,Salmonella 0.9 mg·mL-1 respectively(5)MTT assay and LDH method were used to study the inhibitory effect of strawberry polyphenols on the growth of HepG-2 cells.MTT test results showed that in a certain range,polyphenols can obviously inhibit the growth of Hepg-2 cells,and showed a dose and time effect relationship.The inhibitory rates of Hepg-2 cells were 63.21%,69.33%and 70.72%respectively at 24 h,48 h and 72 h respectively when the concentration of polyphenols was 300 ?g·mL-1.When the concentration of strawberry polyphenols was 300?g ·mL-1,The LDH activity reached 196.55 U·L-1 and 231.03 U· L-1 at 24 h and 48h.