Study On The Extraction、Isolation And Antidiabetic Constituents Of Apple Polyphenols

Apple polyphenols are known as an important bioactivity constituents in apple,their function as natural free radical scavengers and therefore can act as potentialdisease-preventing agent against a range of degenerative diseases, such ascardiovascular disease, cancer and immune system decline. Our team’s preliminarywork found that apple polyphenols could significantly improve the diabetic conditionsin streptozocin (STZ) induced diabetic rats.The study took apple polyphenol extract as the object of the research, which wasbased on the separation method of column chromatography. Of which the objective isto investigate the antidiabetic effect. Firstly, in order to facilitate the isolation, applepolyphenol extract were separated into several parts of different polarity bymacroporous resin column, then different parts of apple polyphenols were tested forthe antidiabetic activity by STZ induced diabetic rats.25compounds were isolatedfrom the antidiabetic part by column chromatography of silica gel, ODS, Toyopearl,Sephadex and PHPLC.23of them were confirmed, their structures were identified asp-Coumaric acid (1), Caffeic acid (2),5-O-p-Coumaroylquinic acid(3),4-O-p-Coumaroylquinic acid(4),4-O-p-Coumaroylquinic acid methyl ester(5),1-O-p-Coumaroylquinic acid methyl ester(6),1-O-caffeoylquinic acid methyl ester(7),1-O-caffeoylquinic acid ethyl ester (8),3-Hydroxyphloridzin (9), Phloretin-2’-xyloglucoside (10),3-Hydroxyphloretin-2’-xyloglucoside(11), Phloretin-2’-xylogalactoside (12),(2R,3R)-(+) Taxifolin(13), Quercitrin (14), Quercetin-3-O-β-D-galactoside (15), Phloretin (16), phloridzin (17),3,5-di-O-Caffeoylquinic acid (18),Cinchonain Ia (19), Rhinchoin Ia (20), Cinchonain Ib (21), Rhinchoin Id (22),Cinchonain Id (23) on the basis of spectroscopic analysis including UV,1D,2D-NMRand MS, and compound8is a new compound, compound19~23were reported inapple for the first time.The chemical constituents of antidiabetic part of apple polyphenols wereanalized by HPLC,14peaks were identified by compared with standard compounds,which accounts for82.1%of the total area of absorption peaks, and the content ofmain compounds was measured by HPLC.The islet cell proliferation experiment indicated that compound1、7、9、11、12、16accelerated the proliferation of the pancreastic β cells, especially compound11andcompound12showed significant activity on islet β cells. The study also determinated total triterpenoids of different apple varieties inapple peel and apple flesh.