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Poly(ethylene glycol) (PEG), a kind of “green” medium, was used to extract artemisinin from the Chinese herb Artemisia annua L. to replace the traditional volatile and explosive solvents like petroleum ether, diethyl ether, etc. PEGs, with different molecular weights, show excellent ability for artemisinin extraction, and the extraction efficiency decreased with the increase of molecular weight. It was also demonstrated that ultrasonic irradiation could further enhance extraction efficiency compared with conventional water bath heating. Results indicate that the extraction amount of artemisinin from one gram of the leaves could reach 15.8 mg/g under the optimal conditions with ultrasonic power of 100 W, the temperature of 50 °C, time of 1 h in PEG-200, which were optimized by response surface method. Compared with Soxhlet extraction using petroleum ether (PE), the method developed here shows higher extraction efficiency (15.8 mg/g for PEG vs. 14.9 mg/g for PE process) and shorter extraction time (1 h vs. ...

Artemisinin is a kind of natural antimalarial drug exhibiting low toxicity and a very fast action against malaria. Solvent extraction is the most widely used method to separate artemisinin from the Chinese medicinal herb Artemisia annua L. In this study, a series of monoether-based solvents were investigated to extract artemisinin, and propylene glycol methyl ether (PGME) was found to be the most appropriate one for this extraction. Ultrasonic irradiation was demonstrated to be able to assist artemisinin extraction. Influence of extraction conditions, including liquid/solid ratio, extraction temperature, ultrasonic time, and ultrasonic power, on the extraction efficiency were discussed by single-factor experiments, and the main influencing factors were optimized by response surface methods. The extraction mechanism was explored using spectroscopic characterizations, and kinetics of this process was also studied. Results indicated that ultrasonic assisted extraction using PGME had faster extraction rate than conventional solvents, and ultrasonic could significantly enhance mass transfer. Compared with conventional extraction, the process developed here exhibited a higher efficiency (13.79 mg g−1vs. 13.29 mg g−1) and shorter extraction time (decreased from 8 h to 0.5 h) at a relatively low temperature. In addition, PGME had low toxicity and volatility, making the extraction process more safe and reliable. Therefore, this proposed method demonstrated that PGME-based ultrasonic assisted extraction is a rapid, efficient, simple and safe technique for natural product extraction.