Optimization ultrasonic extraction process of isoliquiritigenin by orthogonal method

Ultrasonic extraction method was used to extract isoliquiritigenin (ISLG) from Glycyrrhiza uralensis Fisch. The extraction conditions that influenced the extraction yield of ISLG were studied, including volume fraction of alcohol, ratio of liquid to material (g/mL), ultrasonic-irradiation time and extraction times. The results of orthogonal test indicated the optimum ultrasonic extraction conditions of ISLG: volume fraction 80% alcohol as solvent, ratio of liquid to material 10 : 1 (g/mL), ultrasonic extraction time 20 min, 3 times for extraction. The yield of ISLG was 0.37 [per mille] , which was 2.06 times as high as those of heat reflux extraction, 1.54 times of Soxhlet extraction. The mass fraction of ISLG in the crude extracts was 0.55%, which was 3.24 times of heat reflux extraction, 1.45 times of Soxhlet extraction. The results show that ultrasonic extraction is efficient, simple and rapid for extracting ISLG from Glycyrrhiza uralensis Fisch.