Fading Pharmacy
Africa’s antimalarial plants at risk
When the chills and fever of malaria strike, some people East Africa turn to a plant known as Knobwood for relief. An extract taken from the leaves, bark or root can help tame the fever and still the chills. But Knobwood and some of Africa’s other anti-malarial plants are now threatened with over-harvesting and possibly extinction, according to a book published in advance of World Malaria Day on April 25th.
Malaria kills some 800,000 people per year, the majority of whom are children under five years of age in sub-Saharan Africa. In many communities, a lack of doctors and modern drugs leads residents to use natural remedies, which typically come from plants. To identify – and save – those medicinal plants, researchers from the World Agroforestry Centre (ICRAF) in Kenya and the Kenya Medical Research Institute (KEMRI) have collected and analyzed hundreds of species from across East Africa. ICRAF scientists, for instance, identified potentially useful plants by interviewing about 180 herbalists and 100 malaria patients in 30 communities in Kenya, Uganda, and Tanzania, and the Centre now stores about 30 species of antimalarial trees and shrubs in its genebank and nurseries.
The survival of some of those plants in the wild is now in doubt, the researchers conclude in Common Antimalarial Trees and Shrubs of East Africa. The book, published by ICRAF and KEMRI, offers detailed portraits of 22 of the region’s most promising malaria-fighting trees and shrubs. In addition to Knobwood (Zanthoxylum chalybeum), threatened species include the African wild olive (Olea europaea Africana), which is over-exploited for timber.
“We’ve only scratched the surface on the potential value of these plants,” says Geoffrey Rukunga, Director of KEMRI’s Centre for Traditional Medicine and Drug Research and one of the book’s co-authors. “Going forward, I’d like to see more investment and more research on the power of these plants to fight the scourge of malaria and other diseases.”
The authors note that many drugs used to treat malaria originated in plants. Quinine, for instance, was derived from the bark of the Cinchona tree in South America. The world’s newest, most-effective therapeutic treatment for malaria also comes from a plant, the Artemisia annua shrub. Access to artemisinin compounds, however, remains low—around 15 percent in most parts of Africa and well below the World Health Organizations’ 80 percent target. And the malaria parasite is beginning to develop resistance to those compounds and other commonly-used drugs – highlighting the need for new treatements.
“We’re not saying that using these medicinal plants is a replacement for common prevention treatments like bed nets or effective medicines,” said Dr Najma Dharani, an ICRAF consulting scientist. “But we believe that it’s worth learning from communities that have been treating malaria symptoms with plants for hundreds of years… one of these plants could prove to be the next Artemisia, and we need to do our best to preserve the plants that are going extinct.” – David Malakoff | April 21, 2011
Source: N. Dharani et al., Common antimalarial trees and shrubs of East Africa. World Agroforestry Centre (ICRAF), Nairobi, Kenya 2010. http://www.worldagroforestrycentre.org/our_products/publications/details?node=52847
Image © Ivonne Wierink | Dreamstime.com
