Abstract: Response surface methodology was used to optimize the ultrasound-assisted extraction of total phenolic acids from Salvia miltiorrhiza bunge. Leaves. The extraction efficiency of total phenolic acids was investigated with respect to four variables including ethanol concentration, time, temperature and liquid-to-solid ratio. On the basis of a series of one-factor-at-a-time experiments, a polynomial regression model equation was fitted by the combined use of Box-Behnken experimental design and regression analysis. By analyzing the regression model using response surface analysis, the optimum extraction conditions of total phenolic acids from Salvia miltiorrhiza bunge. Leaves. were identified as follows: 63% ethanol concentration, 43 min extraction time, 50.00 ℃ extraction temperature and 33:1 (mL/g) liquid-to-solid ratio, and the extration efficiency of total phenolic acids was up to 7.78% under the optimized conditions. Confirmatory experiments indicated the good prediction ability of the established model.

Key words: Salvia miltiorrhiza Bunge. leaves, total phenolics, ultrasound, response surface analysis