Integrated extraction process to obtain bioactive extracts of Artemisia annua L. leaves using supercritical CO2, ethanol and water

Abstract

Artemisia annua L. is an herb used in traditional Chinese medicine due to presence of biocompounds with biomedical and pharmaceutical applications. In this work, an integrated process for extraction of bioactive compounds present in A. annua leaves was performed. The process comprised two-step extractions: in the first step supercritical carbon dioxide (scCO2) was used as a solvent, and from the solid residue of the supercritical extraction other extracts were obtained (second stage) using ethanol or water as solvents. Single-step extractions using ethanol or water as solvents were also performed for comparison. In all extracts the variables analyzed were overall extraction yield, the content and yield of total phenolic, total flavonoids and artemisinin, as well as antimalarial activity. The supercritical (SC) and ethanolic (E) extracts obtained in a single step showed the highest yields of artemisinin and were very active against Plasmodium falciparum, with IC50 values less than 0.1μgmL−1. On the other hand, the aqueous (SCA) and ethanolic (SCE) extracts from the second extraction step were free of artemisinin, but these extracts contained roughly 90mg of phenolic compounds per gram of extract, including a high overall yield in the aqueous extract. The volatile fraction (SC-V) obtained from the supercritical extraction consisted mainly of camphor. Therefore, the two-step extraction in two steps proved to be advantageous because the residue of supercritical extraction could be used for obtaining aqueous or ethanolic extracts containing phenolic compounds.