Abstract
Artemisia annua is an herbal drug with profound antimalarial activity, which can be ascribed to the sesquiterpene lactone artemisinin. Artemisinin also shows efficacy against other parasitic protozoan species, such as Trypanosoma and Leishmania, however trypanocidal and leishmanicidal effects of A. annua extracts have not been reported so far. In the current study, we evaluated the in vitro growth inhibitory activity of a number of organic and aqueous A. annua extracts, including tinctures, infusions and decoctions against three parasitic protozoa, T. brucei rhodesiense, T. cruzi and L. donovani. Artemisinin content of these extracts was determined by HPLC/DAD/MS. Artemisinin was also evaluated for its antiparasitic activity for comparison. Among the tested extracts, the acetone- and the n-hexane-solubles of A. annua were the most potent against T. b. rhodesiense with IC50 values of 0.30 and 0.455 μg/mL, respectively, whereas the other extracts were ten- to fifty-fold less potent. Neither of the extracts nor artemisinin had trypanocidal activity against T. cruzi (IC50 > 30 μg/mL). Only the organic extracts of A. annua arrested the growth of L. donovani with modest IC50 values (5.1 to 9.0 μg/mL) comparable to that of artemisinin (IC50 8.8 μg/mL). This study highlights significant variations in the artemisinin content of A. annua extracts and underlines the potential of A. annua extracts and artemisinin in the treatment of trypanosomal and leishmanial infections.