Optimization of ultrasound extraction of antibacterial material from Cynanchum atratum Bunge with response surface methodology

In order to study the conditions of extracting antibacterial material from Cynanchum atratum, C.atratum was used as material, the diameter of inhibition zone and Penicillium italicum worked as an indicator and bacterial strain in this experiment respectively, beside these ultrasound-assisted extraction was used to antibacterial material from C. atratum. On the basis of single factor tests, the method of response surface methodology was used to optimize ultrasound-assisted extraction of antibacterial material form C. atratum. The result indicated that the optimal conditions to extract antibacterial material from C.atratum were that ethanol concentration was 50%, extraction time was 2 h, liquid-to-material ratio was 31 and extraction temperature was 69 ℃. Under these conditions, the inhibitory effect against P. italicum by C. atratum extracts was 40.58 mm, close to the theoretically predicted value of 40.81 mm.