Apple Fruit Total Phenols, Chlorogenic Acid And Continuous Separation And Phlorizin Inhibition Of Amylase

An efficient preparative separation of polyphenols from thinned young apples (TYA) has been developed in the present study. X-5resin was verified to offer the best adsorption capacity and desorption ratio for total polyphenols among the eight macroporous resins investigated. Influential factors, such as pH value and concentration of feeding solution, strippant, and adsorption isotherm to the separation of total polyphenols, were successively investigated on X-5resin. After one run treatment, the phenolic content was increased2.12-fold from35.17%to74.64%, with a recovery yield of89.35%. Chlorogenic acid and phlorizin were selectively purified using X-5and polyamide resins. The contents of chlorogenic acid and phlorizin were15.20%and97.52%with recovery yields of89.16%and64.95%, respectively. The method developed will provide a potential approach for its wide industrial and pharmaceutical use.Four kinds of phenolic components were obtained through successive process of separation and purification; they were total polyphenols,30%ethanol eluate,70%ethanol eluate and phlorizin, respectively. The different components described above were examined for their inhibitory effects on human salivary a-amylase. Total polyphenol and30%ethanol eluate significantly suppressed the enzyme activity, while the inhibitory activity of70%ethanol eluate and phlorizin were relatively low. To evaluate the relative potency of total polyphenol and30%ethanol eluate, their concentration required for50%inhibition of enzyme activity (IC50) and maximum enzyme inhibition were determined and compared to the widely used pharmacological inhibitor, acarbose. Results showed that both of total polyphenol and30%ethanol eluate effectively inhibited a-amylase and a-glucosidase. The IC50for α-amylase inhibition of30%ethanol eluate was67.0726±4.12ug/mL, higher than that of acarbose (12.34±1.57μg/mL), while the IC50for a-glucosidase of30%ethanol eluate was42.68±3.47μg/mL, half of that of acarbose (88.53±4.19μg/mL). A kinetic study indicated that30%ethanol eluate was a competitive a-amylase inhibitor, with maximum reaction rate leveling off at approximately6.17×10-4M/min. The active components in30%ethanol eluate which showed strong inhibitory effects on carbohydrate-hydrolyzing enzyme were chlorogenic acid, oligomeric procyanidines, soluble tannins and etc. These results suggest that30%ethanol eluate of phenolic compounds in young apples, a potent inhibitor of carbohydrate-hydrolyzing enzyme, may be useful in pharmaceutical industry to prevent diabetes.