Abstract:

Response surface methodology (RSM) was applied to optimize the ultrasonic-assisted extraction conditions of alkaloids from Semen Strychni. Based on the signal factor test, ethanol concentration, ultrasonic power and extraction time were chosen as casual factors, and a three-factor and three-level Box-Behnken central composite design leading to a set of 15 combinations of these variables was performed to attain the highest weighed value of yields of strychnine and brucine (their weighed coefficients both were 0.5 ). The optimal ultrasonic-assisted extraction conditions were determined as follows: particle size of Semen Strychni 20－40 mesh, ethanol concentration 32.3%, pH 5, ultrasonic power 300 W, ultrasonic-assisted extraction time 37 min, and ratio of liquid to solid 10:1. Under these conditions, the yields of strychnine and brucine were 18.75 mg/g and 9.24 mg/g respectively, which were consistent with the predicted values. These results demonstrate the validity of this extraction process.

Key words: Semen Strychni, alkaloidslultrasonic-assisted extractionlresponse surface methodology