|Illustration from Köhler's Medizinal-Pflanzen|
Strychnos nux-vomica, the strychnine tree, also known as nux vomica, poison nut, semen strychnos, and quaker buttons, is a deciduous tree native to India and to southeast Asia. It is a medium-sized tree in the family Loganiaceae that grows in open habitats. Its leaves are ovate and 2–3.5 inches (5.1–8.9 cm) in size.
Description and properties
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Strychnos nux-vomica is a medium-sized tree with a short, thick trunk. The wood is dense, hard white, and close-grained. The branches are irregular and are covered with a smooth ashen bark. The young shoots are a deep green colour with a shiny coat. The leaves have an opposite decussate arrangement (each opposing pair of leaves at right angles to the next pair along the stem), are short stalked and oval shaped, have a shiny coat, and are smooth on both sides. The leaves are about 4 inches (10 cm) long and 3 inches (7.6 cm) wide. The flowers are small with a pale green colour and a funnel shape. They bloom in the cold season and have a foul smell. The fruit are about the size of a large apple with a smooth and hard shell that when ripened is a mild shade of orange in colour. The flesh of the fruit is soft and white with a jelly-like pulp containing five seeds covered with a soft, woolly substance.
The seeds have the shape of a flattened disk completely covered with hairs radiating from the center of the sides. This gives the seeds a very characteristic sheen. The seeds are very hard, with a dark gray horny endosperm where the small embryo is housed that gives off no odor but possesses a very bitter taste.
The fruit is eaten by monkeys and birds, such as the gray langur.
The strychnine-containing seeds have been used in arrow poison. The use of strychnine is highly regulated in many countries, and it is mostly used in baits to kill feral mammals. Most accidental poisoning is caused by breathing in the powder or by absorption through the skin.
Strychnos is promoted within herbal medicine as being a treatment for a wide range of maladies, including cancer and heart disease. There is, however, no evidence it is useful for treating any condition. Indeed, these seeds contain strychnine poison. The plant appears on the Commission E list of unapproved herbs because it has not been proven to be safe or effective and thus is not recommended for use.
In Ayurveda (the Indian system of Classical medicine), hudar is a mixture containing Strychnos nux-vomica. The seeds are first immersed in water for five days and then in milk for two days followed by their boiling in milk.
It is a major source of the highly poisonous, intensely bitter alkaloids strychnine and brucine derived from the seeds inside the tree's round, green to orange fruit. The seeds contain approximately 1.5% strychnine, and the dried blossoms contain 1.0%. However, the tree's bark also contains brucine and other poisonous compounds.
From acute toxicity experiments done on zebrafish (correlates with mammalian models of organ meridians), it has demonstrated that low concentrations of strychnine changes the phenotype of the heart whilst high concentrations effectively halts heart functionality.  Furthermore, organ toxicity is reversible in certain organs and delayed other organs in zebrafish. Specimens were exposed to the toxins and if left exposed for a day. The heart and central nervous system recovered after 48 hours, whilst the liver and kidney experienced cell death.
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- "Strychnos nux-vomica". Natural Resources Conservation Service PLANTS Database. USDA. Retrieved 4 December 2015.
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- Oudhia, P., 2008. Strychnos nux-vomica L. [Internet] Record from PROTA4U. Schmelzer, G.H. & Gurib-Fakim, A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands.
- "Zebrafish model for assessing induced organ toxicity by Strychnos nux-vomica". Journal of Traditional Chinese Medicine. 36 (4): 522–529. 2016-08-01. doi:10.1016/S0254-6272(16)30070-X. ISSN 0254-6272.
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