Activity correlation between artemisinin and dihydro-artemisinin in fresh isolates of Plasmodium falciparum from Thailand.

Introduction Artemisinin is a sesquiterpene lactone that occurs naturally in the wormweed (Artemisia annua L), an annual plant of wide distribution in the temperate zone between the Balcans and China. Artemisinin was first extracted from the plant, structurally identified and described by Chinese scientists in the early 1970s (1). The compound has strong antimalarial activity directed against asexual and sexual blood forms of all Plasmodium species so far investigated (9). Its blood schizontocidal activity is very rapid, accounting for short fever and parasite clearance times, albeit not exhaustive at the recommended dose regimens and thus fraught with the problem of recrudescence (6). The main indication for the use of artemisinin and its derivatives is the treatment of falciparum malaria, especially in areas with resistance to the common blood schizontocidal compounds.