Purification of Total Flavonoids Extracted from Ponkan (Citrus reticulata Blanco cv. Ponkan) Peel by AB-8 Macroporous Adsorption Resin and Separation of Flavonoid Constituents

Abstract

Objective: To propose an optimal purifi cation process for fl avonoids extracted from ponkan(Citrus Reticulata Blanco cv. Ponkan) peel. Methods: The dynamic adsorption and desorption performance of AB-8 macroporous resin towards flavonoids extracted from ponkan peel was investigated. Major process parameters including sample concentration, pH, fl ow rate, and elution ethanol concentration were evaluated. Then the purifi ed fl avonoids were isolated by chromatographic methods with silica gel and semi-preparative HPLC, and the structures were elucidated on the basis of physicochemical pro perties and spectral data analysis. Results: The optimal purifi cation process was determined as follows: samples at pH 3.0 conta ining 3.03 mg/mL ponan peel fl avonoids were loaded onto the column at a fl ow rate of 3.0 BV/h, and then 90% ethanol was passed through the column to elute the bound flavonoids. After the purification, the purity of ponan peel flavonoids was increased from 17.8% to 63.1%. In addition, eight compounds were isolated from the purifi ed fl avonoids and identifi ed as tangeretin, nobiletin, 4′,5,7,8-tetramethyl-O-isoscutellarein, 5-demethyl-tangeretin, sinetsetin, aurantine, naringin, and hesperidin. Conclusion: AB-8 macroporous resin has a high performance in enriching and purifying fl avonoids from ponkan peel, providing a simple and feasible method. Eight compounds can be isolated from the purifi ed fl avonoids. Moreover, 4′,5,7,8-tetramethyl-O-isoscutellarein, 5-demethyl-tangeretin, aurantine, naringin, and hesperidin are first reported from ponkan peel.