Artemisia annua organic solvent extract, processed by supercritical CO2

BACKGROUND: Artemisia annua L. extraction is traditionally performed using hexane; the process is simple, but not selective. In this work, a strategy to concentrate artemisinin and the other similar active principles in the final extract is proposed, combining cheapness of maceration and selectivity of SC-CO2 processing. RESULTS: Hexane extraction produced a solid, waxy extract with a yield of 3.3% w/w with respect to the starting vegetable material. Then, SC-CO2 processing of this solid extract was performed operating at 0.8 kg h−1 SC-CO2 flow rate and at different operative parameters. Very selective conditions were found operating at 90 bar and 50°C, obtaining a final product containing more than 71% w/w of active compounds (artemisinin, artemisin and dehydroartemisinin). CONCLUSION: Using this approach, a product more than 2.6 times richer in artemisinin than the one obtained by conventional techniques and about 2 times richer than direct CO2 extraction, was obtained. Another relevant result is that the overall process scheme is cheaper than direct CO2 extraction, since a high pressure extractor about 20 times smaller can be used, to process the waxy product obtained by hexane extraction.