In this work, a simple and efficient protocol for the rapid separation of two pairs of isomeric monoterpenes from Paeoniae Alba Radix was developed by combining macroporous resin and elution–extrusion counter-current chromatography. The crude extract was firstly subjected to a D101 macroporous resin column eluted with water and a series of different concentrations of ethanol. Then, effluents of 30 and 95% ethanol were collected as sample 1 and sample 2 for further counter-current chromatography purification. Finally, a pair of isomers, 96 mg of compound 1 and 48 mg of compound 2 with purities of 91.1 and 96.2%, respectively, was isolated from 200 mg of sample 1. The other pair of isomers, 14 mg of compound 3 and 8 mg of compound 4 with purities of 93.6 and 88.9%, respectively, was isolated from 48 mg of sample 2. Their purities were analyzed by high-performance liquid chromatography, and their chemical structures were identified by mass spectrometry and ¹H NMR spectroscopy. Compared to a normal counter-current chromatography separation, the separation time and solvent consumption of elution–extrusion counter-current chromatography were reduced while the resolutions were still good. The established protocol is promising for the separation of natural products with great disparity of content in herbal medicines.

An efficient strategy for extracting and separating five lignans from Schisandra chinensis (Turcz.) Baill has been developed using supercritical fluid extraction (SFE) and high-speed counter-current chromatography (HSCCC) in the present study. First, the extraction was performed by a preparative SFE system under 15 MPa of pressure at 36°C for 4 h. Then, the SFE extract was successfully separated and purified by HSCCC with a two-phase solvent system composed of n-hexane/ethyl acetate/methanol/water (6:4:5:5, 6:4:6:4, 6:4:8:2, v/v) in a stepwise elution mode. The fractions were analyzed by HPLC, and the chemical structures of the products were identified by ESI-MS and ¹H NMR spectroscopy. As a result, a total of 12.5 mg of schisandrin at 98.0% purity, 7.1 mg of gomisin A at 98.1% purity, 1.8 mg of schisantherin B at 93.3% purity, 4.4 mg of deoxyschisandrin at 92.9% purity, and 6.8 mg of γ-schisandrin at 89.1% purity were obtained from 300 mg crude extract in a one-step purification.