Application of microwave-assisted extraction coupled with high-speed counter-current chromatography for separation and purification of dehydrocavidine from Corydalis saxicola Bunting.

Introduction: Dehydrocavidine is a major component of Corydalis saxicola Bunting with sedative, analgesic, anticonvulsive and antibacterial activities. Conventional methods have disadvantages in extracting, separating and purifying dehydrocavidine from C. saxicola. Hence, an efficient method should be established.

Objective: To develop a suitable preparative method in order to isolate dehydrocavidine from a complex C. saxicola extract by preparative HSCCC.

Methodology: The methanol extract of C. saxicola was prepared by optimised microwave-assisted extraction (MAE). The analytical HSCCC was used for the exploration of suitable solvent systems and the preparative HSCCC was used for larger scale separation and purification. Dehydrocavidine was analysed by high-performance liquid chromatography (HPLC) and further identified by ESI-MS and 1H NMR.

Results: The optimised MAE experimental conditions were as follows: extraction temperature, 60 degrees C; ratio of liquid to solid, 20; extraction time, 15 min; and microwave power, 700 W. In less than 4 h, 42.1 mg of dehydrocavidine (98.9% purity) was obtained from 900 mg crude extract in a one-step separation, using a two-phase solvent system composed of chloroform-methanol-0.3 m hydrochloric acid (4 : 0.5 : 2, v/v/v).

Conclusion: Microwave-assisted extraction coupled with high-speed counter-current chromatography is a powerful tool for extraction, separation and purification of dehydrocavidine from C. saxicola.