Optimization of microwave-assisted extracting oleanolic acid and ursolic acid from loquat flowers

This paper aimed at optimizing these conditions of microwave-assisted extracting oleanolic acid (OA) and ursolic acid (UA) from loquat (Eriobotyra japonica) flowers to provide theoretical and technical support for the rational utilization of the flower resources. Single-factor and orthogonal experiments were applied to determine the optimal microwave-assisted extraction conditions and its effectiveness was compared with the other extraction methods. Contents of OA and UA were determined simultaneously by HPLC. Results indicated that the extraction yields of OA and UA were 0.482mg/g dry weight (DW) and 3.118mg/g DW respectively under the optimal microwave-assisted extraction conditions:80% of ethanol concentration, 40∶1 in liquid/solid ratio (mL/g) , 50min in extraction time, 300W for microwave power and extraction at 50℃. Extraction yields of OA and UA by microwave-assisted method were significantly higher than those using ultrasonic-wave assisted extraction and thermo-refluxing extraction techniques.