Separation of lignans from Schisandra chinensis by two-dimensional reversed-phase liquid chromatography

A two-dimensional reversed-phase liquid chromatography (2D-RPLC) method was established to separate lignan components and pure compounds from Schisandra chinensis. This method was based on the modules of separation-enrichment and self-developed with independent intellectual property rights. First, a C-18 column (250 mmx4.6 mm, 5 mu m) was used as the analytical column. A water-methanol mixture was selected as the mobile phase. Separation resolution and retention time were selected as indexes. Gradient chromatography of the lignan extracts was repeated four times and the information was input into XTool, a chromatographic separation software. The conditions for the first- and second-dimensional chromatographic separation were optimized by XTool. Then, linear amplification was used for preparative chromatography. C-18 column (250 mm x 30 mm, 10 mu m) was selected as the first- and second-dimensional separation column. The C-18 columns (80 mmx30 mm, 10 mu m) were selected as enriching columns, and water was chosen as the diluent solution. Lignans from Schisandra chinensis were separated and purified by 2D-RPLC. Finally, nine lignan components were obtained by the first-dimensional separation. Totally, 20 high-purity compounds, containing six monomers, were obtained by the second-dimensional separation. Experimental results showed that this method has good reproducibility. This method thus allows for the systematic separation of lignans from Schisandra chinensis.