Substance toxicologybotany

Aconite: Europe's most toxic plant

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Aconite comes up more than once in Maomao’s own words as the archetype of a merciless poison. When she discusses a poisoning, she remarks that honey from aconite would have settled the matter quickly. Later, she notes that honey gathered from aconite or azalea flowers is no ordinary honey, but a genuine poison to humans. For her, it’s a pharmacist’s plain fact: aconite gives no second chance.

The subject in depth

Aconite, or monkshood, is a mountain plant with blue, helmet-shaped flowers, from the buttercup family [Wikipedia] . The whole plant is toxic, root included, and the root in fact concentrates the most. Its reputation is ancient: it has been called the “queen of poisons” and “wolfsbane,” because it was used to coat bait for wolves.

Helmet-shaped aconite flower and diagram of aconitine's action on the sodium channel
Aconite forces the door

The poison responsible is aconitine, an alkaloid that acts on a precise target: the voltage-gated sodium channels of nerve, muscle, and cardiac cells [Wikipedia] . These channels let sodium in to trigger a signal, then close again so the cell can return to rest. Aconitine forces them to stay open: the cell is continuously excited and can no longer reset.

It’s illuminating to compare this mechanism with that of fugu’s tetrodotoxin. Both poisons target the same sodium channel, but in opposite ways: tetrodotoxin plugs it and cuts the signal, while aconitine jams it open and sends it into overdrive. The clinical outcome converges nonetheless, because in both cases nerve and cardiac command is thrown into disorder.

The first symptoms of aconite poisoning are tingling and numbness of the mouth and extremities, followed by nausea, cardiac rhythm disturbances that can progress to arrest, and progressive paralysis. The course is fast and the lethal dose very small: a few grams of root are enough. There is no specific antidote, only symptomatic care, which fully justifies the reputation the series gives it.

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