Optimization of Purification Technology and Antioxidant Activity of Total Flavonoids from Sea Buckthorn Leaves

China is rich in sea buckthorn (Hippophae rhamnoides L.)resources and a large amount of sea buckthorn fruit is used to extract oil andjuice every year. However, Sea Buckthorn Leaves (SBL), which are full offlavonoids, are discarded as waste. To make full use of resources and turn waste into valuables, theoptimal purification process of flavonoids from SBL was studied and theantioxidant activities of Crude SBL Flavonoids (CFSBL) and Purified Flavonoids (PFSBL)were compared. The macroporous resin which was most suitablefor the purification of CFSBL was selected by comparing the flavonoid content,adsorption rate, desorption rate, and recovery rate in eluant. The purificationprocess of CFSBL was optimized by a single factor, Analytic Hierarchy Process (AHP)and Response Surface Methodology (RSM). 1,1-Diphenyl-2-Picrylhydrazyl(DPPH), hydroxyl radical, and reducing power methods were used to determine theantioxidant activity of CFSBL and PFSBL, respectively.     AB-8 macroporous resin was optimized forpurification and the optimal process was determined by RSM combined with AHP: The ethanol concentrationwas 82.93%, and the sample concentration and elutionvelocity were 0.09 and 1.71 mL/min, respectively. The purity of PFSBL was 84.2%, which was 6.53 times higher than that before purificationand the recovery rate was 69.5%. The scavenging IC₅₀ of DPPH,hydroxyl radical, and reducing the power of CFSBL were 0.016, 1.501, and 0.146mg/mL, respectively. PFSBL were 0.002, 1.131 and 0.051 mg/mL, respectively. Theantioxidant activity of PFSBL was improved compared with that of CFSBL. SBL canbe considered a potential source of antioxidants in food and industry. Thepurification process in this study can enhance the antioxidant activity of SBL.