Ultrasonic Microwave-assisted Extraction Coupled with High-speed Counter-Current Chromatography for the Preparation of Nigakinones from Picrasma quassioides (D.Don) Benn

Introduction Nigakinones are the main effective compounds of Picrasma quassioides (D. Don) Benn and are widely used in traditional Chinese medicine, therefore a rapid and efficient separation and purification method is necessary. Objective To develop a new method based on ultrasonic microwave-assisted extraction (UMAE) and high-speed counter-current chromatography (HSCCC) for the rapid separation and purification of nigakinone and methylnigakinone from P. quassioides (D.Don) Benn. Methodology Response surface methodology (RSM) was used to optimise the extraction conditions of UMAE: 10.0?g of original sample was extracted with 210?mL of 90% (v/v) aqueous methanol at 60 degrees C for 13?min, ultrasonic power was 100?W and microwave power was dynamically adjusted to the given temperature. After extraction, the extract was introduced into the HSCCC and separated with a hexane:ethyl acetate:methanol:2% acetic acid (9:11:9:11, v/v/v/v) solvent system. Results About 2.1?mg nigakinone with purity of 96.8% was obtained in one step within 200?min, methylnigakinone was also obtained with a purity of 75.6%. Their chemical structures were identified with ESI-MS and 1H-NMR. Conclusion UMAE coupled with HSCCC was found to be a promising and feasible alternative method to separate and purify alkaloids from natural herbs such as P. quassiodes. Copyright (c) 2012 John Wiley & Sons, Ltd.