Study On Separation, Purification And Biological Activity Of Polyphenols From Pomegranate Peel

Pomegranate is planted extensively in our country and also has a large output,which ranked firstly in the world. Many related products like pomegranate juice,pomegranate-based cosmetic, pomegranate oil has been developed from pomegranatebecause multiple nutritional value has been found in it. At the same time, a lot differenttypes of side products can be gained from the production of pomegranate-relatedproducts. In this paper, we will talk about the polyphenols and ellagic acid ofpomegranate peel, which are the by-products of pomegranate juice.First, we studied the extraction processes of polyphenol and ellagic acid frompomegranate peel according to the single-factor experiments and orthogonal designexperiment. We confirmed the opital process of polyphenol extraction: the ratio ofpretreated pomegranate peel powder and ethanol (40%) was1:20, heated at50℃for90min, in this condition we got the higher and stable yeild of polyphenol, that was33.5%approximately. We confirmed the opital process of ellagic acid extraction：theratio of pretreated pomegranate peel powder and1mol/L HCl was1:10, heated at50℃for90min, the yeild of ellagic acid was4%approximately.Secondly, we studied on optimizing macroporous resin to separate and purifypolyphenol. Results indicate that macroporous resin SP-700is the best one, whichpossess the strongest absorbend ability and easier desorption property. And confirmedthe basic conditions of polyphenols purification: concentration of polyphenol2mg/mL,pH3.0, flowing rate2.1mL/min, and the eluteethanol concentration90%, elution rate0.8mL/min, with the polyphenols purity increasing from34%to71%. Comparing thepurified and unpurified polyphenols through the high performance liquidchromatography, it was obvious that the macroporous resin had the effect of purifyingpolyphenols. Purified polyphenols include four major substances. They are punicalagin,gallic acid, ellagic acid, protocatechuic acid ordering from higher to lower content ofpolyphenols.Finally, through the vitro antioxidant test and function test, we studied on thecomparing of polyphenols and ellagic acid through the antioxidant ability of hydroxylfree radical, DPPH radical, ABTS+radical, and mice hypoglycemic effect. The resultsindicated that, polyphenols and ellagic acid have antioxidant effects on those freeradical, and the purified polyphenols on hydroxyl radical, DPPH radical, ABTS+radicaland antioxidant capacity is the strongest, superior to that of crude polyphenol and ellagic acid. Hypoglycemic rate by shearing tail and testing blood glucose valuesindicated that hypoglycemic effect of the polyphenols and ellagic acid can obviouslyreduce the blood level of glucose. Purified polyphenol had the best hypoglycemic effect,next was crude polyphenol, ellagic acid was the last.