Ultra‐high‐pressure‐assisted extraction of wedelolactone and isodemethylwedelolactone from Ecliptae Herba and purification by high‐speed counter‐current chromatography

Ultra-high-pressure extraction combined with high-speed counter-current chromatography was employed to extract and purify wedelolactone and isodemethylwedelolactone from Ecliptae Herba. The operating conditions of ultra-high-pressure extraction were optimized using an orthogonal experimental design. The optimal conditions were 80% aqueous methanol solvent, 200 MPa pressure, 3 min extraction time and 1:20 (g/mL) solid-liquid ratio for extraction of wedelolactone and isodemethylwedelolactone. After extraction by ultra-high pressure, the extraction solution was concentrated and subsequently extracted with ethyl acetate; a total of 2.1 g of crude sample was obtained from 100 g of Ecliptae Herba. A two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-water (3:7:5:5, v/v) was used for high-speed counter-current chromatography separation, by which 23.5 mg wedelolactone, 6.8 mg isodemethylwedelolactone and 5.5 mg luteolin with purities >95% were purified from 300 mg crude sample in a one-step separation. This research demonstrated that ultra-high-pressure extraction combined with high-speed counter-current chromatography was an efficient technique for the extraction and purification of coumestans from plant material.