Is artemisinin the only antiplasmodial compound in the Artemisia annua tea infusion? An in vitro study

In our ongoing investigation into Artemisia annua for the treatment of malaria, we decided to study the possibility that synergism might enhance the efficacy of artemisinin. Our main objective was to test tea infusions and nonpolar extracts prepared from different A. annua varieties against Plasmodium falciparum in vitro in order to determine if synergism will increase the effectiveness of artemisinin in the samples as compared to pure artemisinin. We found that the IC50 of artemisinin in the tea and nonpolar extracts was not significantly different to the IC50 of pure artemisinin. We could show that the year and country of harvest or storage conditions did not have any influence on the activity and that it narrowly followed the concentration of artemisinin in all the extracts. In conclusion, based on these in vitro results, artemisinin seems to be the only active antiplasmodial compound in A. annua.