Quinine

An article about the use of quinine in medicine

Quinine is a medication used to treat malaria and babesiosis. It is a naturally occurring alkaloid derived from the bark of the Cinchona tree. Quinine has been used for centuries as an effective treatment for malaria, a disease caused by Plasmodium parasites transmitted through the bites of infected Anopheles mosquitoes.

History

The use of quinine dates back to the early 17th century when it was first introduced to Europe by Jesuit missionaries. The bark of the Cinchona tree, native to the Andean forests of South America, was used by indigenous people to treat fevers. The active ingredient, quinine, was isolated in 1820 by French researchers Pierre Joseph Pelletier and Joseph Bienaimé Caventou.

Mechanism of Action

Quinine works by interfering with the growth and reproduction of the malaria parasite in the red blood cells. It inhibits the parasite's ability to digest hemoglobin, leading to the accumulation of toxic heme molecules, which ultimately kills the parasite.

Medical Uses

Quinine is primarily used to treat uncomplicated Plasmodium falciparum malaria. It is often used in combination with other antimalarial drugs to enhance efficacy and reduce the risk of resistance. Quinine is also used off-label to treat nocturnal leg cramps, although this use is controversial due to potential side effects.

Side Effects

Common side effects of quinine include cinchonism, which is characterized by symptoms such as tinnitus, headache, nausea, and visual disturbances. More severe side effects can include thrombocytopenia, hemolytic anemia, and arrhythmias. Due to these potential adverse effects, quinine use is generally limited to cases where other treatments are not available or suitable.

Biosynthesis

Biosynthesis of quinine

Quinine is biosynthesized in the Cinchona tree through a complex pathway involving several enzymatic steps. The process begins with the amino acid tryptophan and involves the formation of several intermediate compounds before the final quinine molecule is produced.

Cultural and Other Uses

Quinine is also known for its use in tonic water, where it is responsible for the drink's distinctive bitter taste. Under ultraviolet light, tonic water fluoresces due to the presence of quinine, as shown in the image above.

Also see

• Malaria treatment
• Cinchona
• Antimalarial medication
• Cinchonism