Chinese doctors prescribed for thousands of years, and even today it is one of the most effective treatments for malaria. Now, scientists say they have finally discovered exactly how a drug of plant origin called artemisinin kills malaria parasites. The discovery may help develop new weapons against malaria.
Artemisinin and several derivatives are derived from Qinghao, also known as mugwort or Artemisia annua , a long plant known for its antipyretic capacity. Qinghao extracts have recently become very popular in Southeast Asia, where resistance to most other drugs against malaria is endemic, and more and more researchers are studying drugs. But exactly how artemisinin kills the parasite Plasmodium falciparum that causes malaria remained uncertain. Artemisinin has a chemical structure called a bridge peroxide, which can be cleaved by iron ions to form free radicals that attack a range of proteins and other biomolecules; some researchers suspected that such an attack would be fatal for parasites. Others have speculated that, like chloroquine against malaria drug, artemisinin frustrates the removal of heme, a toxic by-product formed during the consumption of the parasite of human hemoglobin.
None of these explanations is correct, according to a team from the University of Liverpool, University of Southampton Medical School and Hospital of St. George in the UK the team noted that the chemical structure artemisinin resembles thapsigargin, an inhibitor of an enzyme present in mammalian cells. Maybe doing something like artemisinin, they reasoned - and of course, artemisinin has proven a powerful specific inhibitor and a similar enzyme, called PfATP6 in Plasmodium . A series of experiments confirmed that the drug's ability to block PfATP6 is also what thwarts the parasites.
"I think their data and I think they have a very strong argument," says molecular epidemiologist Steven Meshnick from the University of North Carolina, Chapel Hill. Yet he says he is not totally convinced yet; the ideal way to nail PfATP6 the goal of artemisinin would find a Plasmodium strain resistant to artemisinin and show that they have a mutation in the gene PfATP6 he said . So far, none of these resistant strains have been found in patients - and no hope to see soon
Related site
malaria information of World health organization
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