Optimization of the Ultrasonic Extraction Technology of Total Flavonoids from Hoya carnosa Leaves by Response Surface Methodology

In order to explore the process conditions of ultrasonic extraction of total flavonoids from the leaves of Hoya carnosa, and promote the development and utilization of Hoya carnosa in Fujian, the leaves of Hoya carnosa were used as the main raw material. Then, the effects of extraction time, solid-liquid ratio and extraction temperature on the extraction rate of total flavonoids from the leaves of Hoya carnosa were investigated by designing the single factor experiment through the ultrasonic-assisted extraction. On this basis, the response surface optimization experiment was carried out. The results showed that the optimum extraction conditions for total flavonoids from the leaves of Hoya carnosa were as follows: the extraction time of 40 min, the solid-liquid ratio of 1∶35, the extraction temperature of 40℃. Under the optimum extraction conditions, the extraction rate of total flavonoids from the leaves of Hoya carnosa was 125.28 mg·g^-1, which was close to the theoretical predicted value of 126.18 mg·g^-1 predicted by the model equation.