Application Of Microwave-Assisted Extraction And Ionic Liquid-based Microwave-Assisted Extraction Of Active Compounds From Traditional Chinese Medicine

Microwave-assisted extraction (MAE) technology uses microwave heating to speed up the solvent in the process of extracting the target compounds from solid samples. Compared with traditional extraction methods, MAE exhibits many unique advantages such as rapidity, high efficiency, and low cost. Ionic liquids (ILs) are not only "environmentally friendly" and "green solvents," they also possess strong polarity, which is helpful in the absorption of microwave energy. Therefore, ILs are good extractants for MAE. Microwave-assisted extraction and ILs as solvent combination of microwave-assisted extraction have promising potential in the application of the extraction of active compounds from Traditional Chinese Medicine (TCM). In this paper, we used these technologies to extract active compounds from TCM, as follows:An MAE method was developed for extracting mollugin from R. cordifolia. Several variables that can potentially affect the extraction efficiency, namely extracting solvent, microwave power, extraction time and solid-liquid ratio, were optimized. The extraction efficiency of mollugin from R. cordifolia with MAE was higher than conventional extraction methods such as Soxhlet extraction, heat reflux extraction, and ultrasonic-assisted extraction. Due to the considerably shortened process time (from 4h to 4min) and its higher extraction efficiency (from 5.10 to 6.24mg/g), the proposed MAE procedure is obviously a more rapid and effective sample preparation technique.The application of ionic liquid-based microwave-assisted extraction (ILMAE) for extracting the phenolic alkaloids present in samples of the medicinal plant Nelumbo nucifera Gaertn. as well as three alkaloids, namely, N-Nornuciferine, O-nornuciferine and nuciferine, from the lotus leaf was successfully developed. The performance of various ILs with different cations and anions, the concentration of the selective ILs, and the microwave parameters including microwave power, extraction time, and solid-liquid ratio were systematically optimized. Compared with the regular MAE and conventional heat reflux extraction (HRE), these proposed approaches exhibited higher efficiency and shorter extraction time, indicating that ILMAE is an efficient, rapid, and simple sample preparation technique.