Efficient combination of circulating ultrasound-assisted extraction and centrifugal partition chromatography for extraction and on-line separation of chemical constituents from Stellera chamaejasme L.

INTRODUCTION: Sample preparation is a crucial step in medicinal herb analysis because the desired chemical components need to be extracted from the herbal materials for further separation and characterisation. Thus, the development of " modern" sample preparation techniques with significant advantages over conventional methods is very important. OBJECTIVE: The aim of this study was the development of a new preparation method using circulating ultrasonic-assisted extraction (CUAE) coupled with centrifugal partition chromatography (CPC) for continuous extraction and on-line isolation of chemical constituents from Stellera chamaejasme L. METHODOLOGY: The stationary or mobile phase was used as the extraction solvent. Extraction parameters, including the ultrasound power, extraction time, temperature, and liquid:solid ratio, were optimised using a response surface methodology. RESULTS: The extraction time, temperature, and power considerably affected the extraction yield. The optimised extraction parameters were an ultrasound power of 800 W, extraction time of 30 min, extraction temperature of 70 °C, and liquid:solid ratio of 8 mL/g. The solvent system for CUAE and CPC was optimised using mathematical equations, and the two-phase solvent system of n-hexane:ethyl acetate:methanol:water at a volume ratio of 3:5:4:6 was calculated. Four target compounds (daphnoretin, chamaechromone, neochamaejasmin A, and isochamaejasmin) with purities above 96% were successfully extracted and isolated on-line via CUAE/CPC. CONCLUSION: Compared with the reference extraction methods, the instrumental setup achieved a scientific and systematic extraction and isolation of natural products and has great potential for industrial application.

Ultrafiltration liquid chromatography combined with high-speed countercurrent chromatography for screening and isolating potential α-glucosidase and xanthine oxidase inhibitors from Cortex Phellodendri.

Cortex Phellodendri is a typical Chinese herb with a large number of alkaloids existing in all parts of it. The most common methods for screening and isolating alkaloids are mostly labor intensive and time consuming. In this study, a new assay based upon ultrafiltration liquid chromatography was developed for the rapid screening of ligands for α-glucosidase and xanthine oxidase. The C. Phellodendri extract was found to contain two alkaloids with both α-glucosidase- and xanthine oxidase binding activities and one lactone with α-glucosidase-binding activity. Subsequently, with the help of high-speed countercurrent chromatography, the specific binding ligands including palmatine, berberine, and obaculactone with purities of 97.38, 96.12, and 96.08%, respectively, were successfully separated. An optimized low-toxicity two-phase solvent system composed of ethyl acetate/n-butanol/ethanol/water (3.5:1.7:0.5:5, v/v/v/v) was used to isolate the three compounds mentioned above from C. Phellodendri. The targeted compounds were identified by liquid chromatography coupled with mass spectrometry and NMR spectroscopy. Therefore, ultrafiltration liquid chromatography combined with high-speed countercurrent chromatography is not only a powerful tool for screening and isolating α-glucosidase and xanthine oxidase inhibitors in complex samples but is also a useful platform for discovering bioactive compounds for the prevention and treatment of diabetes mellitus and gout.