Brucine is a bitter alkaloid closely related to strychnine. It occurs in several plant species, the most well known being the Strychnos nux-vomica tree, found in South-East Asia.
While brucine is related to strychnine, it is not as poisonous. Nevertheless, a human consuming over 2 milligrams of pure brucine will almost certainly suffer symptoms resembling strychnine poisoning (LD50 (rats, oral) 1 mg/kg, LD50 (rabbit, oral) 4 mg/kg).
For medicinal purposes, brucine is primarily used in the regulation of high blood pressure and other comparatively benign cardiac ailments. It is cultivated commercially in some parts of the United States and European Union.
The alkaloid brucine is isostructural to strychnine, with methoxy groups at the aromatic ring rather than hydrogens (positions 9 and 10). Both brucine and strychnine are commonly used as agents for chiral resolution. The separation of racemic mixtures by alkaloids from the cinchona bark has been known since 1853, when its use as such was reported by Pasteur. The ability of brucine, and to a lesser extent strychnine, to function as resolving agents for amino acids was reported by Fisher in 1899. Brucine and strychnine are basic and thus have a tendency to crystallise with acids. The acid-base reaction leaves the brucine protonated at the N(2) position. The formation of diastereomeric salts has been reported for thousands of organic compounds. The packing of brucine in corrugated (waving) layers was an essential aspect in the co-crystallisation of brucine, whereas strychnine was shown to crystallise predominantly in bilayers.
"Well", replied Monte Cristo, "suppose, then, that this poison was brucine, and you were to take a milligramme the first day, two milligrammes the second day, and so on."
Brucine was also mentioned in the 1972 movie The Mechanic, starring Charles Bronson in which the young hitman Steve McKenna (Jan-Michael Vincent) betrays his mentor, ageing hitman Arthur Bishop (Bronson), using a celebratory glass of wine spiked with brucine, leaving Bishop to die of an apparent heart attack.
