Malaria is a fever illness which also existed in Uppsala during Linnaeus' time. It was treated with among other things the bark of the cinchona tree which reduced the fever. At that time people didn't know that malaria was caused by a parasite. Today the malaria parasite is resistant to many medicines. Scientists are therefore looking for new plant substances which can be effective against the parasite. One of them is artemisinin which can be found in the herb sweet wormwood.
Bark for Malaria
As early as the 16th century quinine bark was being used to treat fevers. It was found that the bark from the quinine bark tree, the various Cinchona-species, was effective against remittent fever, or malaria as we say today. Great quantities of bark were therefore transported from South America to Europe.
The discovery has been assumed to be due to brothers of the Jesuit order and it was hence commonly traded under the name Jesuit bark. It is sometimes also called China bark, but the name has nothing to do with China; it derives from the Indian name of the bark, quina-quina or kinakina. During the 18th century it was found that it also stimulated the heart. In 1820 two French pharmacists isolated a substance from the bark, quinine.
In 1820 it was shown that a salt, quinine sulphate, was excellent for treating fevers. Several similar substances have been refined since then, amongst them is quinidine which is still being used for cardiac illnesses.
At the beginning of the 20th century, plantations of quinine bark were opened in Indonesia and therefore the collection of bark in South America was discontinued. Quinine was an unbeatable product against malaria. During the Second World War the Japanese occupied the quinine bark plantations which led to a shortage of quinine for the allied troops. This led in its turn to the production of synthetic products based on the chemical structure of quinine.
By the end of the war, virtually only synthetic malaria products were being used. However, the malaria parasite managed in time to develop resistance and survive many of these synthetic products. In some areas quinine still works, but the parasite is starting to survive even medication with quinine, which calls for the development of new anti-malarial drugs. As an alternative, artemisinin, a substance from sweet wormwood and derivatives is beginning to be used.
Sweet wormwood – a new product for malaria
Sweet wormwood, Artemisia annua, grows mainly in South East Asia and is related to common mugwort and absinth. Linnaeus cultivated sweet wormwood in Linnaeus’ Garden in Uppsala but it was probably not because he was aware of its medicinal properties. In China at the end of the 1960s they began extracting malaria-active substances from plants. One of the plants studied was sweet wormwood, which had been recommended in China for fevers as early as 340 BC. They extracted a substance which was named artemisinin after the scientific name Artemisia.
Today, Artemisinin is widely used in certain countries in South East Asia, since the malaria parasite has developed resistance to many of the other anti-malaria products. A normal period of treatment lasts for 5 to 7 days.
So far, artemisinin is effective against most of the malaria parasites, but if it is used too frequently, the parasites may become resistant. Resistance may develop when the parasite gets used to otherwise lethal substances in low concentrations.
The advantage with artemisinin is, among other things, that the amount of parasites in the blood is reduced by half within just a few hours, thus making it difficult for the parasite to develop resistance. On the other hand, quinine has a half-life of 2-3 weeks.