RESUMEN
The extraction conditions and antioxidant activities of rutin from Sophora japonica bud by deep eutectic solvents were investigated. Box-Behnken design was used to optimize the extraction conditions and the scavenging activities of DPPH, O2- and ·OH of purified rutin were evaluated. The highest yield of 279.8 mg/g was achieved in the extraction medium of choline chloride/triethlene glycol (1/4) under the optimum conditions: water content of the DES 18.1%, extraction time 28.3 min, extraction temperature 70 °C and liquid-solid ratio 10 mg/1 g. The highest extraction amount was slightly different from the predicted value of the established second-order polynomial equation. In addition, The EC50 of DPPH scavenging, O2- scavenging and ·OH scavenging of rutin were 5.68 µg/mL, 0.19 and 0.28 mg/mL, respectively. The above results indicate rutin extracted by the choline chloride/triethylene glycol has excellent antioxidant activity and was an admirable free radical scavenger.