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The strychnine tree (Strychnos nux-vomica L.) also known as nux vomica, poison nut, semen strychnos and quaker buttons, is a deciduous tree native to India, and 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.
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.
The use of strychnine is highly regulated in many countries, and is mostly used in baits to kill feral mammals, including wild dogs, foxes, and rodents. Most accidental poisoning is by breathing in the powder or by absorption through the skin .
S. 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, short stalked, are oval shaped, also 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 with 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 which when ripened is a mild shade orange 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 are removed from the fruit when ripe. They are then cleaned, dried and sorted. 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 grey horny endosperm where the small embryo is housed that gives off no odour but possesses a very bitter taste. The plant is native to southeast Asia and Australia normally in tropical and subtropical areas.
There are no uses in modern medicine, although it was widely used in medicine before World War II. It is also used in preparation of the popular homeopathic remedy Nux Vomica (Nux-V). Strychnine is a deadly poison with a lethal dose to humans of about 30 to 120 mg. Survival of substantially higher doses have been reported. The properties of Nux Vomica are those of the alkaloid strychnine. Strychnine is eliminated with a half-life of about 12 hours.
One report published in 1923 described a case involving a 2½ year old who had eaten thirty-two "Nuxated Iron" tablets and died of strychnin poisoning about two hours after he had taken the tablets. These patent medicine tablets contained nux vomica extract, but the quantity in each tablet could not be guaranteed, as there was no law requiring such labelling at the time. 
The most direct symptom caused by strychnine is violent convulsions due to a simultaneous stimulation of the motor or sensory ganglia of the spinal cord. During the convulsions there is a rise in blood pressure. Brucine closely resembles strychnine in its action, but is slightly less poisonous, as it only causes paralysis of the peripheral motor nerves.
In vitro Strychnos nux-vomica inhibited the growth of AGS human gastric carcinoma cells.
In the Indian (Ayush) system of medicine, "hudar" is a mixture containing Strychnos nux-vomica and used to elevate blood pressure. The seeds are first immersed in water for five days, in milk for two days followed by their boiling in milk. In India, the quality/toxicity of traditional medical crude and processed Strychnos seeds can be controlled by examining the toxic alkaloids using established HPLC methods and/or HPLC-UV methods.
Strychnos has not been proven effective for the treatment of any illness. Since the seeds contain strychnine poison, conventional doctors do not recommend it as a medicine. It is on the Commission E list of unapproved herbs, because it is not recommended for use and has not been proven to be safe or effective. There is also no clinical trial evidence of Strychnos supporting it being a viable cancer treatment.
- Harry L. Arnold (1968). Poisonous Plants of Hawaii. Tokyo, Japan: Charles E. Tuttle. p. 20. ISBN 0-8048-0474-5.
- 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.
- David Michael Wood, Emma Webster, Daniel Martinez, Paul Ivor Dargan & Alison Linda Jones (2002). "Case report: survival after deliberate strychnine self-poisoning, with toxicokinetic data". Critical Care 6 (5): 456–459. doi:10.1186/cc1549. PMC 130147. PMID 12398788.
- Barker, E.O. (1923). ""NUXATED IRON" NOT ALWAYS "NUX"-LESS". JAMA 81 (4): 319. doi:10.1001/jama.1923.02650040059035. Retrieved 16 September 2014.
- Govinda Rao Duddukuri, A. Naga Brahmam & D. N. Rao (2008). "Suppressive effect of Strychnos nux-vomica on induction of ovalbumin-specific IgE antibody response in mice" (PDF). Indian Journal of Biochemistry & Biophysics 45 (5): 341–344. PMID 19069846.
- Sang Man Lee, Jae Im Kwon, Yung Hyun Choi, Hyun Sup Eom & Gyoo Yong Chi (2008). "Induction of G2/M arrest and apoptosis by water extract of Strychni Semen in human gastric carcinoma AGS cells". Phytotherapy Research 22 (6): 752–758. doi:10.1002/ptr.2355. PMID 18446845.
- Seema Akbar, Shamshad A Khan, Akbar Masood & M Iqbal (2010). "Use of Strychnos nux-vomica (azraqi) seeds in Unani system of medicine: role of detoxification". African Journal of Traditional, Complementary and Alternative Medicines 7 (4): 286–290. PMC 3005396. PMID 21731158.
- Q. B. Han, S. L. Li, C. F. Qiao, J. Z. Song, Z. W. Cai, P. Pui-Hay But, P. C. Shaw & H. X. Xu (2008). "A simple method to identify the unprocessed Strychnos seeds used in herbal medicinal products". Planta Medica 74 (4): 458–463. doi:10.1055/s-2008-1034359. PMID 18484543.
- Roland Hofbauer, Eva Pasching, Doris Moser & Michael Frass (2010). "Heparin-binding epidermal growth factor expression in KATO-III cells after Helicobacter pylori stimulation under the influence of Strychnos nux-vomica and Calendula officinalis". Homeopathy 99 (3): 177–182. doi:10.1016/j.homp.2010.05.002. PMID 20674841.
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