Antimalarial plants 'in danger of extinction'

[NAIROBI] More research is needed to prevent the extinction of trees and shrubs with antimalarial properties that could guide the discovery of new generation of anti-malarials and other life-saving drugs, African scientists have said.

Many of the plants used in traditional medicines to prevent or treat malaria are endangered by deforestation and overexploitation for medicinal use, according to research findings released today in a book (21 April) in Nairobi, Kenya.

The book, Common Antimalarial Trees and Shrubs of East Africa, written by researchers at the World Agroforestry Centre (ICRAF) and the Kenya Medical Research Institute (KEMRI), summarises research from African laboratories and field data collected from traditional healers and malaria patients in more than 30 East African rural communities.

The authors said that over one thousand plant species are used by traditional healers against malaria symptoms. They focused on 22 of these species for whose medicinal properties there is also some scientific evidence that warrants further study.

Some of the species identified as endangered are knobwood, Zanthoxylum chalybeum, and the African wild olive, Olea europaea Africana.

ICRAF is already working to preserve some of the endangered species: it holds close to 200 African species, of which more than 30 are known to have anti-malarial properties, in its genebank and plant nurseries at the headquarters in Nairobi.

Farmers could help with the conservation of such plants if governments provided them with incentives, one of the book's authors, Geoffrey Rukunga, director of KEMRI's Centre for Traditional Medicine and Drug Research, said. "This will mean moving [the endangered plants] from the wild to farmlands."

He added that vigorous dissemination of information on the importance of these species is crucial if the danger of extinction is to be contained.

Current malaria drugs quinine and artemisinin are also based on ingredients derived from plants but malaria parasite has started to evolve resistance to these treatments. Further research into these plants used by traditional healers in East Africa could yield the "next artemisinin", the researchers said.

They also called for more research to understand how traditional healers combine the different plants to boost their effectiveness, so that pharmaceutical companies can design future treatments based on such knowledge. 

Rukunga said these plants should also be researched for possible cures for other diseases such as tuberculosis.

Elizabeth Juma, of the Division of Malaria Control in Kenya's Ministry of Health, said: "Most compounds used for [malaria] treatment came from plants or have had a plant base and as our repertoire diminishes, it is more important that new compounds are discovered. These will likely come from plants."

Tony Simons, ICRAF's deputy director general, said 80 per cent of the people in Africa depend on traditional medicines that combine different plants. 

"Our interest [in these species and the medicines derived from them] is in preservation, research, safety, efficiency, production and use as well as affordability," he said.

Link to book

Link to SciDev.Net's Spotlight on Integrating Modern & Traditional Medicine