Quinine
There are 23 accepted species in the genus Cinchona; Cinchona calisaya is grown in the glasshouses at Oxford Botanic Garden. These trees, with their glossy, evergreen leaves and terminal panicles of red, pink or white flowers, can reach around 12 metres in height. They are naturally distributed in the Andes, in humid, but cool, montane forests. It is the bark that has been instrumental in curing malaria due to the presence of anti-malarial alkaloids such as quinine. Other alkaloids in the bark are extracted for the treatment of ailments such as cardiac arrhythmia.
Cinchona is named after the Comtesse de Chinchon, wife of the Viceroy of Peru, who was cured of malaria using the bark of Cinchona in the 1630s. Legend also says that on her return to Spain in the 1640s, she introduced the bark to treat fevers in the area where she lived near Madrid. Whether Amerindians used the bark as an indigenous remedy for fevers has been the subject of much academic discussion. Jesuit missionaries worked in Peru in the early sixteenth century and so perhaps it was the missionaries who first took the cure back to Europe rather than the Countess. One of its common names, Jesuits' bark, reflects this belief. However, it was some time before this 'miraculous cure' of powdered bark was accepted by European doctors as they had their own 'cures' for malaria from which they gained financially. By the late seventeenth century quinine bark was widely used as a malarial remedy.
Not all Cinchona bark have good concentrations of the alkaloids and there is considerable variation between species and even within species. Consequently, barks from different sources have different efficacies. Seed must be collected from trees rich in quinine alkaloids. The Dutch plants some particularly high-yielding trees in Java, and for nearly 100 years extracts from trees dominated the world's quinine supply. But, when the Japanese arrived in Java during the Second World War this market domination ended.
The quinine synthesis by American scientists in 1944 is thought to have been an important step in the course of the war. The evolution of malaria parasites that are resistant to synthetic quinine means that production of natural quinine remains important, especially in Indonesia and the Democratic Republic of Congo, together with India, Bolivia, Colombia and Kenya.
And finally, a further use of the bitter bark is as the flavouring agent of tonic water.
Further reading
Lewington A 1990. Plants for people. Royal Botanic Garden Kew.
Harris SA 2015. What have plants ever done for us? Bodleian Library.
Hobhouse H 2005. Seeds of change: Six plants that transformed mankind. Counterpoint.
Lucinda Lachelin