The Tree that Kills Malaria — and the Mosquitoes

Scientists at the University of Oslo have examined the bark from two African trees and found substances that can kill both the mosquitoes that transmit malaria, and the parasite itself.

Oslo/Norway — Researchers at School of Pharmacy at the University of Oslo in Norway have shown that bark from two trees in the citrus family (Rutaceae) contains substances that not only kill the malaria parasite, but also the mosquitoes that transmit the disease.

“This project started in 2011, when we were approached by the entomologist Bertin Mikolo fra Marien Ngouabi University(link is external) in the Republic of Congo's capital Brazzaville. He had learned that local traditional healers were using extracts from the bark of a tropical tree to kill malaria mosquitoes and other insects, and he had demonstrated that the extracts could kill weevils and cockroaches. Now, he wanted Norwegian assistance to investigate whether the bark also contained substances that could kill malaria mosquitoes”, professor emeritus Karl Egil Malterud explains.

Malaria is a disease caused by tiny parasites of the genus Plasmodium, which spend part of their life cycles in the blood vessels of humans and other mammals. The parasite is transmitted between humans during bites from mosquitoes of the genus Anopheles.

The scientists found several interesting substances both in the so-called Olon tree (Zanthoxylum heitzii) that is found from Cameroon to Congo, and in a related tree from Mali. The most interesting and active compounds were found in the Olon tree, but also the bark of Zanthoxylum zanthoxyloides from Mali contains active substances.

“We produced extracts from the bark of the Olon tree and found that it contained at least one compound that kills the mosquitoes that transmit the malarial parasite. But the bark also contains another substance that kills the parasite itself”, says Associate Professor Helle Wangensteen. She has been the leader of this project.