ABSTRACT
This chapter discusses some antimalarial plants that have been well studied, and from which compounds have been isolated and found to be active against Plasmodium. Hepatic metabolism is postulated to be the main elimination pathway for artemisinin, which has a high hepatic extraction ratio of 0.93. Artemisinin derivatives are metabolized by CYP450 enzymes to the more potent dihydroartemisinin. The exact mechanism of artemisinin remains to be resolved, although it has been postulated to be involved in interference of heme detoxification. An aqueous infusion contains more artemisinin as compared to a decoction, as artemisinin is heat labile. To reduce development of resistance as well as taking into account the short half-life of artemisinin, artemisinin and its derivatives should not be used as monotherapy for malaria but instead with another antimalarial agent. Trials on individual alkaloids confirm their efficacy as antimalarials. Quinine overdosage may cause oculotoxicity, cardiotoxicity, hypotension, and cardiovascular collapse.
