Brucine and Strychnine? Count on it.

If you’re watching The Count of Monte Cristo on PBS or have read the novel by Alexandre Dumas (1844), you are aware of the potion brucine. The novel takes place during the Bourbon Restoration in France and spins a tale about the unjust imprisonment of young Edmond Dantès. During his incarceration, he meets the learned Abbé Faria, who teaches Edmond many things, including the chemistry of potions and poisons. After his escape, Edmond uses brucine in a diabolical poison plot of revenge.

In a recent episode of another PBS program, Miss Scarlet, about a Victorian era woman detective, Eliza Scarlet realizes the deaths of two men were the result of strychnine poisoning and not tetanus. Symptoms of tetanus resemble those of strychnine, but the disease is not infectious and thus could not have been transmitted from one man to another.

Poisons are the classic weapons for murder used in fiction (as well as in real life!) because they are ubiquitous and easy to administer. Just a few drops in tea will do (see my Poison Blog from June 1, 2024, The Russians have a Tender Spot for Poison). Those who have read the brilliant novelist Agatha Christie's works have seen her use multiple poisons, but she favored cyanide, arsenic, and strychnine.

Brucine is an analogue of strychnine, and both are found together in the seeds of Strychnos nux-vomica, a tree native to India and Southeast Asia. However, brucine is found at a concentration of about one percent compared to strychnine and is less active (less potent) than strychnine. 

Strychnos nux-vomica fruit and seeds

Strychnine is a powerful central nervous stimulant and convulsant, causing paralysis of the respiratory muscles. The crystalline powder is odorless and colorless and has a bitter taste when dissolved in water. Victims poisoned with strychnine experience painful muscle spasms, seizures, and rhabdomyolysis (a condition where skeletal muscle cells break down, and the filtered proteins from the blood damage the kidneys). In depictions of death due to strychnine on film, the victim usually writhes with involuntary spasms soon after ingestion and dies in a contorted arch of the spine, sometimes with a malevolent grin from the painful contractions of the facial muscles (risus sardonicus).

However, it’s the dose that makes the poison. Paracelsus, the 16th-century Swiss physician and chemist, told us so. Both strychnine and brucine have been used medicinally for hundreds of years. These drugs improved circulation and muscle tone, and strychnine was used as a respiratory, cardiac, and digestive stimulant.

Poisoning from strychnine results from either oral ingestion, dermal exposure, or parenteral (i.e., intramuscular or intravenous) administration, the latter being the most toxic. It is rapidly absorbed in the GI tract. Symptoms of oral poisoning occur within 15 to 60 minutes after ingestion.

Strychnine competitively inhibits the binding of glycine (a major inhibitory neurotransmitter in the spinal cord) to a subunit of the chloride channel, resulting in increased impulse transmission to the muscles. Without glycine inhibition, muscles continually contract. Tetanus toxin produces symptoms similar to those of strychnine by preventing the release of glycine rather than acting as a competitive agonist.

While strychnine is no longer used as a medical therapy, it may still be found in some Traditional Chinese Medicines or some homeopathic therapies, and as a selective rodenticide.

Whether it is an old story or a new one, brucine and strychnine aid a murderous plot. You can count on it.