Purification of Eremophilane‐Type Sesquiterpenes from Ligularia atroviolacea by High Speed Countercurrent Chromatography

Abstract

Following an initial cleanup step on the C18 open column chromatography, a preparative high speed countercurrent chromatography (HSCCC) method for isolation and purification of 8β‐H‐eremophil‐3,7(11)‐dien‐12,8α; 15,6α‐diolide, and furanoeremophil‐3‐en‐15,6α‐olide from the Chinese medicinal plant Ligularia atroviolacea was successfully established by a one‐step separation, using n‐hexane‐ethyl acetate‐ethanol‐water (4∶1∶4∶1, v/v/v/v) as the two phase solvent system. The upper phase was used as the mobile phase in the head to tail elution mode. HPLC analysis of the fractions collected on the preparative HSCCC of 600 mg of crude extracts showed that the purity of 8β‐H‐eremophil‐3,7(11)‐dien‐12,8α; 15,6α‐diolide (54.7 mg) was 98.1% and that of furanoeremophil‐3‐en‐15,6α‐olide (41.8 mg) was 98.4%. The chemical structures of the two eremophilane‐type sesquiterpenes were identified by ESI‐MS, 1H‐NMR, and 13C‐NMR analysis. To the best of our knowledge, 8β‐H‐eremophil‐3,7(11)‐dien‐12,8α; 15,6α‐diolide was obtained from L. atroviolacea for the first time, while furanoeremophil‐3‐en‐15,6α‐olide was first isolated as a natural product.