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An effective method based on medium‐pressure liquid chromatography and recycling high‐speed counter‐current chromatography for enrichment and separation of three minor components with similar polarity from Dracocephalum tanguticum
- Yang, Xue, Wang, Nana, Shen, Cheng, Li, Hongmei, Zhao, Jingyang, Chen, Tao, Li, Yulin
- Journal of separation science 2019 v.42 no.3 pp. 684-690
- Dracocephalum, countercurrent chromatography, ethyl acetate, hexane, high performance liquid chromatography, methanol, plant extracts, recycling, solvents
- The separation of minor compounds, especially those with similar polarities from a complex sample, remains challenging. In the proposed study, an effective method based on medium‐pressure liquid chromatography and recycling high‐speed counter‐current chromatography was developed for the enrichment and separation of three minor components from Dracocephalum tanguticum. The crude extract was directly introduced to medium‐pressure liquid chromatography for the enrichment of the three minor components. Based on high‐performance liquid chromatography analysis, the total content of these three compounds increased from 0.48% in the crude extract to 85.3% in the medium‐pressure liquid chromatography fraction. In addition, high‐speed counter‐current chromatography was employed to separate the enriched compounds using the solvent system hexane/ethyl acetate/methanol/water (1.18:8.82:1.18:8.82, v/v/v/v). As a result, compound 3 and a mixture of compounds 1 and 2 were obtained. In order to improve the resolution of compounds 1 and 2 while saving separation time, a recycling and heart‐cut mode was used. Finally, compounds 1 and 2 were obtained after five cycles. These compounds were identified as 3‐phenylethyl β‐d‐glucopyranoside (1), tazettoside E (2), and cirsiliol‐4′‐glucoside (3). Compounds 1 and 2 were primarily separated from D. tanguticum. Moreover, the developed method provided a reference for the separation of minor components from the complex sample.