Old cure may offer new malaria option.

An herbal-tea remedy for malaria contains a component that may form the basis of a novel drug against the disease, tests in mice show. The compound, called tazopsine, is derived from the bark of a tree (Strychnopsis thouarsii) found in Madagascar's eastern rain forest.

In lab dishes, tazopsine killed the two common malaria parasites Plasmodium falciparum and Plasmodium yoelii. Tests in mice newly infected with P. yoelii showed that tazopsine given orally protected 70 percent of the animals, the researchers report in the December 2006 PLoS Medicine.

But tazopsine proved toxic at high doses, limiting the amount that could be given. To get around that, the researchers broke down tazopsine into seven constituent parts. They found that one, dubbed NCP-tazopsine, killed the parasite as well as the whole compound did.

When the scientists gave a quadrupled dose of NCP-tazopsine to mice heavily infected with P. yoelii, the chemical caused no side effects and killed all the parasites before they could pass through the animals' livers and infect their bloodstreams.

Although it remains unclear how NCP-tazopsine works, the findings suggest that it might prevent malaria from causing illness in newly infected people, such as travelers, soldiers, or others passing through malarial zones, the researchers say. But before it's given to people, NCP-tazopsine must pass tests in chimpanzees against P.falciparum, the parasite strain that causes the most-severe malaria. The researchers also are planning tests of whether the compound eradicates parasites lying dormant in monkeys' livers, says study coauthor Dominique Mazier, a parasitologist at Pierre and Marie Curie University in Paris.--N.S.