Abstract: The polyphenols from young pear fruits were purified by 5 kinds of macroporous adsorption resins, and their antioxidant activity was determined. The results indicated that NKA-9 resin had better adsorption and desorption properties than four other resins. Therefore, it was the most suitable resin to purify polyphenols from young pear fruits. The optimum conditions for purification were as follows: after pH adjustment to 5.0, the polyphenol at 2 mg/mL was passed through the resin at a flow rate of 1 mL/min, followed by desorption with 70% ethanol at a flow rate of 1 mL/min. Under these conditions, the purity of the polyphenols from young pear fruits increased from 6.23% to 30.68%. Both the crude and purified samples had the ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) radicals and nitrite, with IC50 values of 151.07, 152.48 and 490.35 mg/mL versus 122.12, 130.78 and 392.09 mg/mL, respectively. Conclusively, the antioxidant capacity of the purified polyphenols was better than that of the crude sample.

Key words: macroporous resins, polyphenols from young pear fruits, purification, antioxidation