15/02/07

Scientists boost production of cheap malaria drugs

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Scientists have developed ways of increasing the artemisinin yield from the herb Artemisia annua by specifying optimal growing conditions and improving the extraction process.


The two developments could bring down the price of artemisinin-based drugs recommended by the World Heath Organization to treat malaria. Over 100 countries use it to fight malaria parasites that have become resistant to the drug chloroquine.


A study, published in the Journal of Agricultural and Food Chemistry this week (13 February), found that growing Artemisia annua in fertiliser-poor “acidic soils with a mild potassium deficiency” increased the yield of artemisinin by 20 per cent.


Synthesising artemisinin in the lab produces yields lower than four per cent, so the plant is the only commercial source of the compound.


This could lead to cheaper drugs, as well as benefiting small-scale farmers who have no choice but to grow their crops in poor soils.


The economic gains are clear for farmers who could make “savings in potassium, gains in artemisinin production”, said the study’s author, Jorge Ferreira of the US-based Appalachian Farming Systems Research Center.


Pedro Melillo, a horticulturalist from the State University of Campinas, Sao Paulo, Brazil, welcomed the news saying potassium is one of the most expensive fertilisers in Brazil.


He told SciDev.Net that the cultivation method could help develop a strategy for using Artemisia annua as a traditional herbal tea to tackle malaria for poor communities who cannot access or afford to pay for antimalarial products developed by the pharmaceutical industry.


A separate study explored new technologies to make extracting artemisinin cheaper and more environmentally friendly.


The current process uses the solvent hexane, which is both highly toxic and explosive.


Researchers at the UK-based University of Bath examined alternative extraction technologies using the non-flammable solvents supercritical carbon dioxide, hydrofluorocarbon, ionic liquids or ethanol.


They found that these alternative solvents gave faster extraction times and a more complete extraction of the useful substances in the Artemisia annua leaf.


The study was published in the Journal of Natural Products in November.


Reference:
Journal of Agricultural and Food Chemistry doi 10.1021/jf063017v S0021-8561(06)03017-2
Journal of Natural Products 69, 1653 (2006)

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