Optimizing the Ultrasound-Assisted Extraction of Total Cardiac Glycosides from the Milk of Calotropis Gigantea with Response Surface Methodology

The ultrasound-assisted extraction was carried out to separate the total cardiac glycoside from the milk of Calotropis gigantea, and the extraction factors was optimized by response surface method using the Box–Behnken design (BBD) on total cardiac glycoside extraction was determined and optimized. A quadratic polynomial parameter mathematical model was established. Under the optimized conditions of ethanol concentration = 40% (vol), liquid-material ratio = 40 : 1, ultrasound power = 420 W and ultrasonic time = 30 min, the total cardiac glycoside yield is 12.75%, which is very close to the predicted value of 12.48%. The model predicts the experimental data well and has a high determination coefficient (R² = 0.992). The variables that have a greater influence on the extraction yield were selected as ultrasonic power, ultrasonic time, ethanol concentration and liquid-material ratio, respectively.