Optimization of ultrasound-assisted deep eutectic solvents extraction of rutin from Ilex asprella using response surface methodology

Taking the extraction amount of rutin as the index, the extraction process of rutin from Ilex asprella (Hook. et Arn.) Champ. ex Benth. using the ultrasonic-assisted deep eutectic solvent method was optimized through response surface method. The effects of various factors, including the types of deep eutectic solvent, molar ratio of the solvent, water content, liquid-solid ratio, the temperature, power and time of ultrasound on the extraction amount of rutin were investigated. In accordance with the result of univariate experiments, the extraction process was optimized through employing the Box-Behnken response surface design method. A three-factor, three-level experimental model was established with the liquid-solid ratio, water content and ultrasonic time as variables. The findings indicated that the optimal technological conditions were as stated below: the molar ratio of lactic acid to choline chloride at 1:1, the ultrasonic extraction temperature at 40 °C, the ultrasonic extraction time at 31 min, the water content at 28%, and the liquid-solid ratio at 20:1 mL/g. Under optimal conditions, the validation experimental result revealed that the extraction amount of rutin was 86.553 ± 1.35 µg/g, with an absolute error of less than 0.6% in comparison with the predicted value of the model. The use of deep eutectic solvents for the extraction of rutin and the application of response surface method for optimizing the extraction process of rutin from Ilex asprella (Hook. et Arn.) Champ. ex Benth. were demonstrated. The present study provided a reference for the comprehensive utilization of Ilex asprella (Hook. et Arn.) Champ. ex Benth..