Optimization of Extraction Process of Forsythioside A, Forsythin and Rutin from Forsythia suspensa Leaves Based on Response Surface Methodology and Entropy Weight Method

In this paper, the ultrasonic extraction technology of Forsythia suspensa leaves was optimized based on multi-index components. The contents of forsythioside A, forsythin and rutin were determined by high performance liquid chromatography (HPLC). The ethanol concentration, liquid-solid ratio, extraction time and extraction temperature were taken as the factors. The entropy weight method was used to obtain comprehensive score by calculating the weight coefficient of each index. Subsequently, the comprehensive score was taken as the index. Finally the Box-Behnken response surface methodology was adopted to optimize the extraction process. The optimum extraction conditions of Forsythia suspensa leaves were as follow: Ethanol concentration 50%, liquid to material ratio 28:1 mL/g, extraction temperature 51 ℃, extraction time 25 min. The results of the validation tests showed that under the optimal conditions, the extraction amount of forsythioside A, forsythin and rutin were 69.69, 22.87 and 22.46 mg/g, respectively, the RSD was less than 3% and comprehensive score was 32.18. The extraction technology was stable and feasible, and the extraction quantity of active components was high. It was suitable for the extraction of Forsythia suspensa leaves.