Optimization of Ultrasonic Assisted Extraction of Total Flavonoids from Hibiscus tilisceus Leaves by Response Surface Methodology and Its Scavenging Ability of Nitrite

In order to improve the utilization rate of Hibiscus tiliaceus resources, the ultrasonic-assisted extraction process of total flavonoids from Hibiscus tiliaceus leaves was studied and the scavenging ability of nitrite was also investigated. Single factor experiments were performed on ultrasonic temperature, ultrasonic time, ethanol concentration and liquid-to-material ratio using extraction yield as the response value. Response surface methodology was used to optimize the extraction conditions of total flavonoids from Hibiscus tiliaceus leaves. The scavenging ability of nitrite was determined using V_C as contrast. The results showed that the optimal conditions for extracting total flavonoids from Hibiscus tiliaceus leaves were as follows:Ultrasonic temperature 74℃, for 29 min, ethanol concentration 58%, liquid-to material ratio 29:1 mL/g. Under these conditions, the extraction yield of total flavonoids from Hibiscus tiliaceus leaves was 38.15 mg/g. The relative error from the predicted value was 0.73%. The optimized process had high accuracy and reliability. There was a dose-effect relationship between the total flavonoids extracted from Hibiscus tiliaceus and the clearance rate of nitrite, which indicated that the total flavonoids had good nitrite scavenging ability.