WU Yonghua, LIU Enqi, ZHANG Jianping, CHEN Shanglong, CHEN Anhui, SHAO Ying
The purification process of hawthorn leaf polyphenols was investigated, and its antioxidant activity and constituents were analyzed. The adsorption properties of selected four macroporous resins (SP-825, D101, AB-8, XDA-2) for hawthorn leaf polyphenols were compared, the optimum purification resins were screened and the purification parameters were optimized. The antioxidant activity, composition and infrared spectroscopic characteristics of hawthorn leaf polyphenols were investigated. The results showed that AB-8 resin possessed the best effect on the purification of hawthorn leaf polyphenols. The optimum purification parameters were as follows, initial sample solution pH 4.5, sample concentration 0.064 mg/mL, sampling flow rate 1.5 mL/min, elution flow rate 0.6 mL/min with 70% ethanol. Under these conditions, the recovery rate was 78.25%, the purity of polyphenol was increased by 4.15 times after purification. The crude extract and purified substance of hawthorn leaf polyphenols showed good antioxidant activity, the IC50 values of DPPH· scavenging capacity were (1.28±0.14) μg/mL and (0.78±0.09) μg/mL respectively, the IC50 values of Fe2+ chelating capacity were (55.58±1.24) μg/mL and (34.13±1.02) μg/mL respectively, the IC50 values of total reduction power were (3.66±0.18) μg/mL and (2.12±0.23) μg/mL respectively, the IC50 values of purified hawthorn leaf polyphenols for ·OH scavenging capacity were (4.49±0.16) μg/mL, which indicated that the antioxidant capacity of the purified substance of hawthorn leaf polyphenols was significantly improved compared with the crude extracts. FTIR analysis showed that the purified hawthorn leaf polyphenols had characteristic peaks of polyphenols and flavonoids, HPLC analysis showed that the purified hawthorn leaf polyphenols mainly contained chlorogenic acid, epicatechin, ferulic acid, rutin and ursolic acid, which indicated that hawthorn leaf polyphenols have good utilization and development prospects.