Variation in artemisinin and flavonoid content in different extracts of Artemisia annua L.

Artemisia annua L. is a promising and potent antimalarial drug. This activity has been ascribed to its content of artemisinin, a sesquiterpene lactone that is stage specific and very effective against drug-resistant Plasmodium species and which has low toxicity. The in vitro antiplasmodial activity of artemisinin is enhanced by the flavonoids of the extract, as recently proposed by the authors. Different extracts (tinctures, infusions and decoctions), obtained from a cultivar selected by the University of Campinas (0.52% artemisinin), were analyzed in order to prove the selectivity of the solvents to obtain high yields of both artemisinin and flavonoids. Tinctures 40 and 60% v/v showed a greater power of extraction in comparison with infusions and decoctions. The best performance was obtained using 60% v/v tincture. The extraction efficiency for artemisinin was 40% and for flavonoids was 29.5%. Among aqueous extracts, the best results were obtained by preparing an infusion with boiling water, left to cool for 15 minutes before filtration. The extraction efficiency for artemisinin was 57.5% and for flavonoids was 8.2%. If leaves are boiled for several minutes the artemisinin concentration is decreased, probably due to the heat instability of this constituent. Also microwave could represent a valid alternative method to extract the phytocomplex, the extraction efficiency for artemisinin was 4 1.0% and that for flavonoids was 7.7%.