Efficient determination of three flavonoids in Malus pumila flowers by ionic liquid-HPLC

Simultaneous determination of phlorizin, astragalin and afzelin in Malus pumila flowers was performed by high performance liquid chromatography (HPLC) with 1-butyl-3-methylimidazolium bromide [BMIM]Br/methanol as an extract method. The effects of different extracts of M. pumila flowers on tyrosinase activity were evaluated. Based on the total content of phlorizin, astragalin and afzelin as indicators, the optimum extraction technology of M. pumila flowers was determined by the Box-Behnken designed with five-factors-three-levels. The optimum conditions were determined as following: smashing mesh number, 70 mesh; concentration of extraction, 0.52 mol/L; ultrasonic time, 60 min; solid-liquid ratio, 1:100; and centrifugal speed, 7000 r/min. Under optimal conditions, the total content of phlorizin, astragalin and afzelin was 181.03 mg/g (n = 6). After the addition of ionic liquid, the extraction rate of phlorizin, orientin and aflatoxin in M. pumila flowers was increased by 25.4%. Methanol extract of M. pumila flowers had an activation effect on tyrosinase, while methanol ion liquid extract had an inhibitory effect on tyrosinase.