RESUMEN
Object A novel microwave-heated extraction (MHE) method was studied for the extraction of glycyrrhizic acid from Glycyrrhiza uralensis Fisch. Methods Several factors, such as temperature, time and microwave power were investigated and the appropriate MHE conditions were obtained from the orthogonal test. Under the optimum conditions, the optimal solvent was selected and the MHE was compared with ultrasonic extraction, leaching at room temperature and Soxhlet extraction,. Results The optimum conditions of MHE is extracting for another 40 min in 0.5% ammonia water after heated to 60 ℃ by microwave of 2 000 W. Yield of glycyrrhizic acid was about equal to that of Soxhlet extraction for 4 h, and that of leaching at room temperature for 44.3 h. Conclusion The MHE method is fast, efficient, energy-saving and high-selective, which is recommendable to the application to active compounds extraction from Chinese herbal medicines.