Optimal Extraction Technology of Indigo Naturalis by Uniform Design

OBJECTIVE To optimize extraction process of Indigo Naturalis by uniform design. METHODS The process was studied by uniform design method with the extraction ratio of indirubin as the index, and four factors were chosen, including ethanol volume, ethanol concentration, extraction time and the extraction times. RESULTS The factors influenced the indirubin extraction was ethanol concentration＞ethanol volume＞extraction time＞extraction times. Extraction time, ethanol volume and ethanol concentration were positively correlated with the extraction efficiency. CONCLUSION The results indicate that the optimum extraction technology is as follows: 10 times volume of 90% ethanol, 0.5 h reflux and extraction for 2 times.