This blog post is going to focus on the genus Cinchona, which is the source of the antimalarial drug quinine.
The Quechua peoples of Peru, Bolivia and Ecuador were the first to realise the medicinal properties of Cinchona. Though now famous as a cure for malaria, the Quechua used the tree’s bark as a muscle relaxant to treat shivering. Since shivering can be one of the symptoms of the disease, the bark was coincidently used to treat malaria. The Quechua’s use of Cinchona was observed by Jesuit missionaries, who introduced the plant to Europe by the 1630s.
In 1677, the use of the bark as a treatment for malaria was first noted in the London Pharmacopoeia, a reference text of different medicines. During his reign, the English King Charles II contracted malaria. He was treated by Robert Talbor, who used Cinchona bark mixed with wine to fight off the disease. He later went on to treat the son of Kind Louis XIV of France of the same disease.
In 1738, Charles Marie de La Condamine produced a paper that identified three separate species of Cinchona from his travels from Ecuador. This paper and a specimen from La Condamine were then used by the Swedish botanist Carl Linnaeus, who named the tree Cinchona. The name was based on a 16th century Spanish Countess of Chinchon, who contracted malaria and was cured with bark from the tree by the Quechua people. Linnaeus’ species was later named as Cinchona officinalis after he established his binomial system for classifying plants.
The bark of the Cinchona tee contains a number of medicinal compounds, including quinine and quinidine. Quinidine is used in pharmaceuticals as an antiarrhythmic agent, suppressing abnormal rhythms of the heart and regulating the heartbeat. Cinchona has been used in folk medicine to stimulate appetite, promote discharge of bile and treat mild influenza infections.
However, the most well-known use of Cinchona is as a source of the antimalarial compound quinine. Quinine is a crystalline salt that has antimalarial, fever-reducing, painkilling and anti-inflammatory properties. Though it is frequently found in antimalarial drugs, the compounds mechanism of action is still not fully understood. Even so, the bitter tasting quinine compound is included in many drugs treating malaria. Cinchona bark is still the most economically viable source of the compound, despite it being possible to synthesise quinine in a laboratory. Quinine has not been the primary treatment for malaria since 2006, when the World Health Organisation (WHO) recommended that the drug artemisinin become the standard cure. Now quinine is used when artemisinin is not available.
Despite being an effective malarial treatment, quinine is not entirely safe. It can cause a condition called cinchonism, which can range from mild to severe. Mild conditions mainly involve reversible symptoms, such as skin rashes, dizziness and vomiting. Severe symptoms of cinchonism can involve temporary deafness, paralysis, blindness and death. Death is usually by pulmonary oedema, which is fluid accumulation in parts of the lungs.
Cinchona and homeopathy
It is said that the birth of homeopathy came about from Cinchona. Homeopathy is a form of alternative medicine in which it is believed that a substance that causes the symptoms of a disease in healthy people will cure similar symptoms in sick people. Samuel Hahnemann (1755-1843), the founder of homeopathy, came across the tree when he was translating William Cullen’s work on the Materia Medica. In it, Cullen documented that the bark could be used to treat intermittent fevers and shivering. Hahnemann began taking a large dose of Cinchona daily for two weeks. He started to develop symptoms that resembled malaria. Though he attributed the symptoms to a hypersensitivity to the bark, this experiment gave Hahnemann the idea that ‘like cures like’, which he later developed into the idea of homeopathy.
Gin and Tonic
Quinine extracted from Cinchona is they key ingredient in tonic water, a carbonated soft drink. The dissolved quinine gives tonic water a distinctive bitter flavour, which is often used to compliment the alcoholic drink gin. The quinine content gives tonic water fluorescent properties under ultraviolet (UV) light. It can even fluoresce in direct sunlight as quinine is extremely sensitive to UV.
Tonic water was first produced in the early 19th century, when British officials stationed in tropical colonial outposts began mixing quinine with carbonated water and sugar to alleviate the bitterness of quinine. They later started mixing this medicinal tonic with gin to create the classic ‘gin and tonic’ combination.