Researchers develop new method for extracting malaria treatment

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New technologies to make the large-scale extraction of the natural antimalarial drug artemisin both cheaper and greener are being developed and trialled in a new European programme.

Since it was first extracted from the herb sweet wormwood (Artemisia annua) by Chinese scientists in the 1980s, artemisinin has proven to be a potent anti-malarial, with most patients treated with artemisinin-based combination treatments (ACTs) showing clinical improvement within 24 hours.

However, large-scale production of artemisinin drugs has so far relied on extraction technology using the hexane – a toxic and potentially explosive hydrocarbon.

In 2005 a team of chemical engineers from the University of Bath in the UK, along with a specialist company, FSC Development Services Ltd, were commissioned by the non-profit organisation Medicines for Malaria Venture (MMV) and the Dutch government to evaluate a range of technologies with the potential to replace hexane extraction.

Alexei Lapkin from the university’s Department of Chemical Engineering has shown three extraction processes can compete with hexane extraction economically, as well as being better for the environment.

Now, using a £500,000 grant from the Dutch Government through MMV, these technologies will be demonstrated and tested over the next 12 months by a consortium of European companies and universities.

“The intention for this project is to build a small-scale demonstrator unit in Bath and prove its viability by extracting artemisinin from Artemisia annua plants grown in different countries and regions,” said Lapkin.

“The project will also explore purification methods of raw extracts to obtain material of good enough quality for pharmaceutical companies to buy for further processing into drug treatments.”

The research team examined alternative extraction technologies using either supercritical carbon dioxide (scCO2), hydrofluorocarbon HFC-134a, ionic liquids (ILs) or ethanol as alternative solvents.

They found that the technologies using scCO2, HFC and ILs, all of which are non-flammable solvents, gave faster extraction times and a more complete extraction of the useful substances in the leaf.

Ionic liquid and HFC-134a technologies in particular showed considerable promise, and the analysis suggests that they could compete with hexane extraction in terms of cost-effectiveness.

Over the next nine months, a demonstrator unit using HFC-134a will be built at the University of Bath in collaboration with the company Ineos Fluor. Bioniqs Ltd, a spin-off company from University of York in the UK, will work on ionic liquids extraction, and University of Bremen in Germany will be testing extraction with another widely used solvent, ethanol.

Ian Bathurst, Director of Drug Discovery & Technology at MMV said developing technology that makes the extraction process as efficient and cost-effective as possible makes the mass production of artemisinin economically, environmentally and socially viable. “This will have a significant impact on the new ACTs we are developing.”