Abstract: In this study,total flavonoids from Malus torigoides were ultrasonically extracted by alkaline water. The effects of solid to liquid ratio,ultrasonic temperature,power and time on the extraction yield of flavonoids were investigated and these parameters were optimized using single factor and orthogonal experiments. In addition,the content and antioxidant activity of the extracted total flavonoids were determined. The results showed that the optimal extraction conditions were solid to liquid ratio of 60:1 mL/g,ultrasonic temperature of 35 ℃,ultrasonic time of 8 min,ultrasonic power of 126.5 W. Under the optimized conditions,the content of flavonoids was 13.1432%. Antioxidant analysis showed that the extract had strong reducibility and scavenging capacity against DPPH free radicals with an IC₅₀ value of 2.39 mg/L and hydroxyl free radicals with an IC₅₀ value of 0.45 mg/L,and these activities were concentration dependent.

Key words: Malus toringoides, flavonoids, ultrasonic extraction, antioxidant activity