Microwave-assisted extraction of lactones from Ligusticum chuanxiong Hort. using protic ionic liquids

Traditional Chinese medicine is still the main source for medical treatment in China. Extraction processes are usually adopted to separate bioactive ingredients from local plants. However, volatile traditional organic solvents are commonly used in the extraction process, which would lead to solvent loss and environment pollution. In this work, in order to improve the extraction process and develop a greener process, a microwave-assisted extraction (MAE) method was investigated to extract senkyunolide I, senkyunolide H and Z-ligustilide from Ligusticum chuanxiong Hort. Two ionic liquids, N, N-dimethyl-N-(2-hydroxyethoxyethyl)ammonium propionate (DMHEEAP) and N, N-dimethyl(cyanoethyl)ammonium propionate (DMCEAP), were employed as extractants. Important factors such as system temperature, extraction time, solid-to-solvent ratio and particle size were studied. The results show the system temperature was main factor which affects the microwave assisted extraction process. The extraction equilibrium could be reached in a short period of time. The extraction efficiency was not affected by the phase ratio within a certain solid/solvent ratio range. The particle size of Ligusticum chuanxiong powder had no remarkable effect on extraction efficiency. The back-extraction of protic ionic liquids using n-hexane was realized, and the concentration of senkyunolide I and senkyunolide H hardly decreased, but the concentration of Z-ligustilide decreased by 39.7%. The extraction mechanism of the investigated microwave assisted ionic liquid extraction was the same as traditional organic solvent extraction.