A molecular target for the class of anti-malaria drugs called artemisinins has been identified, researchers report in this week's Nature (Vol. 424, No. 6951, 21 Aug. 2003, pp. 957-961).
Artemisinins have become increasingly important for treating malaria as resistance to existing drugs spreads. In some parts of southeast Asia they are the only effective anti-malarial. They were discovered in the 1970s - extracted from the Chinese herb quingao or sweet wormwood (Artemisia annua), a long-recognised anti-malarial remedy. Their mode of action however, remained obscure. The leading theory was that artemisinins interact with haem molecules, a breakdown product of the malaria parasite's human red-blood-cell meal. The interaction was thought to release massive quantities of free radicals - enough to kill the parasite.
Not so, find Sanjeev Krishna and colleagues. They show that artemesinins block the action of a metabolic enzyme called PfATP6 that is crucial to the life of the parasite. The finding could eventually lead to the manufacture of synthetic artemisinins with greater preference for PfATP6. In the short-term, studying the genetics of PfATP6 in populations of wild parasites could help to pre-empt resistance that has rendered other drugs useless, the researchers claim.
Krishna's work "has a practical significance beyond its undoubted scientific merit," comments Robert Ridley in an accompanying News and Views article.
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