Orthogonal array design for the optimization of supercritical fluid extraction of tanshinones from Danshen

Different from the west medicine, the therapeutic effect of the traditional Chinese medicine is usually based on multifarious essential components or the combination of them instead of only one component. In this paper, a novel supercritical fluid extraction (SFE) method has been developed for extracting tanshinones (dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone II(A)) from Danshen, the dried root of Salvia miltiorrhiza. Various experimental conditions were investigated to optimize the SFE. Under the appropriate conditions, extracting at 40 MPa, and 50 degrees C and with CO(2) flow rate of 25 L/h for 1 h, SFE can achieve a better yield as well as the recoveries of the tanshinones than the conventional extraction using methanol. Moreover, the target compounds were analyzed by HPLC with a C(18) RP column by gradient elution using ACN and water as mobile phase at a flow rate of 1.0 mL/min and with UV detection at 270 nm. Four calibration equations were then established and good linear relationships were shown (r(2) >0.999) in the investigated concentration range. The recoveries, measured at three concentration levels, varied from 97.2 to 103.8%. The method provided in this article could be applied as an improved quality control method for Danshen products.