RESUMO
To optimize the extraction technology of the total saponins in Dipsaci Radix, the extraction efficiency of total saponins was investigated with respecting to three variables including time, ethanol concentration 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 central composite experimental design and regression analysis. By analyzing the regression model using response surface analysis, the optimum extraction conditions of total saponins from Dipsaci Radix were identified as follows: 7 times of 55% alcohol, refluxing 3 times, 2.8 hours every time, and the extraction efficiency of total saponins was up to 0.201 1 g·g-1 and the asperosaponin Ⅵ was up to 0.015 4 g·g-1 under the optimized conditions. Confirmatory experiment indicated the good prediction ability of the established model and provided the basis for further development and utilization of Dipsaci Radix.