Separation of astragaloside IV from Astragalus membranaceus based on high‐speed countercurrent chromatography in continuous injection mode

Abstract Introduction Astragaloside IV (AS‐IV) is an index for the quality evaluation of the traditional Chinese medicine Astragalus and an important material basis for Astragalus to exert its medicinal effects, and it is difficult to obtain a single AS‐IV by ordinary separation methods. Objective To find a new isolation method that can prepare AS‐IV quickly and efficiently. Methodology AS‐IV was isolated from Astragalus membranaceus extract by high‐speed countercurrent chromatography using a two‐phase solvent system consisting of ethyl acetate/ n ‐butanol/water (4.2:0.8:5, v/v) at a speed of 950 rpm at a flow rate of 2 mL/min using one of the high‐speed countercurrent chromatographic sequential injection models developed during the previous study. Results Compared with the common countercurrent chromatographic separation, this separation method increased the injection volume and yield by 4‐fold and 4.47‐fold, respectively, with only about 1.2‐fold increase in solvent consumption and separation time, and the purity was basically not reduced, and 55.9 mg of AS‐IV, with a purity of 96.95%, was finally prepared from 400 mg of the crude extract in 240 min. Conclusion The continuous injection mode of high‐speed countercurrent chromatography was able to successfully prepare a large amount of AS‐IV with high purity at one time.