"Gin and tonic has saved more Englishmen's lives, and minds, than all the doctors in the Empire."
– Winston S. Churchill

This week’s leaf is all about #quinine, an #alkaloid from #cinchonatree bark.

The history of quinine is closely tied to European imperialism. Spanish conquistadors in the Andes learned how native Inca healers were using cinchonabark to treat high fevers. This knowledge and the tree itself quickly spread to Europe. The botanical medicine proved particularly effective against #malariaand served a vital tool in protecting European colonists in Asia and Africa.

Quinones and related alkaloids in cinchona likely serve the same purpose of alkaloids in other plants: their bitter taste deters grazing herbivores insects. Why in the bark? I’ve said it before – this is where sugary tree sap flows and also where trees produce lots of other phenolic phytochemicals that go into lignin.

Modern quinine (identical to the naturalmolecule) is produced synthetically, as first achieved in 1944 by celebratedchemist and 1965 Nobel laureate RB Woodward.

Malaria is caused by the mosquito-bornebacterium Plasmodium falciparum that invades red blood cells and breaks down the #haemoglobin.Quinine inhibits this activity. However, it is unlikely that a daily dose of gin with quinine-flavoured tonic water (see quote) is enough to provide muchantimalarial protection. At therapeutic doses (in quinine pills), actually hassignificant side effects. Quinine derivatives such as chloroquine are more effective against malaria, though recent claims that it is also effectiveagainst COVID-19 have proved unfounded.

A recent article (Zang et al, 2021) proposesan intriguing new use of quinine as a topical agent for treating atopic dermatitis. Perhaps we at @Green Mountain Biochem should take note, since this skincondition is one the therapeutic targets for our botanical products.

Reading list

·      Achan, Jane et al. “Quinine, an old anti-malarial drug in a modern world: role in the treatment of malaria.” Malaria journal vol.10 144. 24 May. 2011, https://doi.org/10.1186/1475-2875-10-144

·      Wikipedia, “Plasmodium falciparum” https://en.wikipedia.org/w/index.php?title=Plasmodium_falciparum&oldid=1070144136 

·      Wikipedia, “Chloroquine”, https://en.wikipedia.org/w/index.php?title=Chloroquine&oldid=1073478886

·      Zhang Q, et al. Therapeutic effects of quinine in a mouse model of atopic dermatitis. Mol Med Rep. 2021;23(5):313. https://doi.org/10.3892/mmr.2021.11952

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