Separation of polyphenols from blueberry based on antioxidative activities

Based on the determination of antioxidative activity,the extraction procedure of higher pure polyphenol from blueberry was optimized.The crude extracts were obtained by using different polar solvents( water,n- butyl alcohol,70% ethanol,methanol,ethyl acetate) from blueberry fruit. The ethyl acetate,n- butyl alcohol and water liquid- liquid extracts were orderly obtained from macroporous resin enrichment material after methanol extracted.The antioxidative activity of these extracts were measured in vitro by the method of DPPH( 1,1- diphenyl- 2-picrylhydrazyl) and ABTS( 2,2'- azino- bis( 3- ethylbenzthiazolne- 6- sulfonic)). The results showed that all these extracts had antioxidative activity,the active components of the crude extracts mainly existed in methanol,70%ethanol and n- butanol parts.The antioxidative activities of liquid- liquid extracts after macroporous resin enrichment order by polyphenols extracted with n- butanol > those extracted with water > those extracted with ethyl acetate.The activity of these extracts was significantly correlated with total polyphenol content,not with total anthocyanin content.This showed that blueberry polyphenols with strong free radical scavenging effects can be obtain with polar solvent.The optimal blueberry polyphenol extraction procedure based on antioxidative activity was confirmed as: blueberry was extracted with 70% ethanol containing 0.3% trifluoroacetic acid,then absorbed with LS- 305 macroporous resin,firstly eluted with aqueous solution congtaining 0.3% trifluoroacetic acid to remove impurities,then eluted with methanol containing 0.3% trifluoroacetic acid,the eluent was concentrated at 40℃ under reduced pressure to remove solvents and then redissolved in water,extracted with ethyl acetate to remove impurities again,the rest was extracted with n- butanol,concertrated the n- butanol part at 60℃ under reduced pressure and freeze- drying.