Calabar Bean

November 28th, 2007

Botanical Name: Physostigma venenosum (EALF.)
Family: Fabaceae / N.O. Leguminosae

Synonyms: Ordeal Bean. Chop Nut.Calabar bean , physostigma , ordeal bean , esere nut, faba calabarica
Part Used: The seeds.
Habitat: West Africa, Old Calabar. Has been introduced into India and Brazil.

Description:The Calabar bean is the seed of a leguminous plant, Physostigma venenosum, a native of tropical Africa. It derives its scientific name from a curious beak-like appendage at the end of the stigma, in the centre of the flower; this appendage, though solid, was supposed to be hollow (hence the name from Ï†á¿¦ÏƒÎ±, a bladder, and stigma). The plant has a climbing habit like the scarlet runner, and attains a height of about 50 ft., with a stem an inch or two in thickness. The seed pods, which contain two or three seeds or beans, are 6 or 7 inches in length; and the beans are about the size of an ordinary horse bean but much thicker, with a deep chocolate-brown color.

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The plant came into notice in 1846 and was planted in the Edinburgh Botanical Gardens, where it grew into a strong perennial creeper. It is a great twining climber, pinnately trifoliate leaves, pendulous racemes of purplish bean-like flowers; seeds are two or three together in dark brown pods about 6 inches long and kidney-shaped thick, about 1 inch long, rounded ends, roughish but a little polished, and have a long scar on the edge where adherent to the placenta. The seeds ripen at all seasons, but are best and most abundant during the rainy season in Africa, June till September. The natives of Africa employ the bean as an ordeal owing to its very poisonous qualities. They call it esere, and it is given to an accused person to eat. If the prisoner vomits within half an hour he is accounted innocent, but if he succumbs he is found guilty. A draught of the pounded seeds infused in water is said to have been fatal to a man within an hour.

Constituents: The chief constituent is the alkaloid physostigmine (eserine), with which are calabarines, eseridine, and eseramine. Eseridine is not employed medicinally.

Chemistry:
The seeds contain the alkaloid physostigmine (eserine) in a concentration of about 0.15%, along with the related alkaloids eseramine, physovenine, calabatine, and geneserine, among others. These alkaloids are derived from a tryptophan precursor. On exposure to air, physostigmine oxidizes to a reddish compound, rubreserine, and therefore should be protected from air and light.
Medicinal Action and Uses: Chiefly used for diseases of the eye; it causes rapid contraction of the pupil and disturbed vision.Also used as a stimulant to the unstriped muscles of the intestines in chronic constipation. Its action on the circulation is to slow the pulse and raise blood-pressure; it depresses the central nervous system, causingmuscular weakness; it has been employed internally for its depressant action in epilepsy, cholera, etc., and given hypodermically in acute tetanus. Physostigmine Salicylas is preferred for the preparation of eyedrops.

They constitute the E-ser-e or ordeal beans of the people of Old Calabar, being administered to persons accused of witchcraft or other crimes. In cases where the poisonous material did its deadly work, it was held at once to indicate and rightly to punish guilt; but when it was rejected by the stomach of the accused, innocence was held to be satisfactorily established. A form of dueling with the seeds is also known among the natives, in which the two opponents divide a bean, each eating one half; that quantity has been known to kill both adversaries. Although thus highly poisonous, the bean has nothing in external aspect, taste or smell to distinguish it from any harmless leguminous seed, and very disastrous effects have resulted from its being incautiously left in the way of children. The beans were first introduced into England in the year 1840; but the plant was not accurately described till 1861, and its physiological effects were investigated in 1863 by Sir Thomas R. Fraser. The bean usually contains a little more than 1% of alkaloids. Of these two have been identified, one called calabarine with atropine-like effects, and the other, now a highly important drug, known as physostigmine, used in the treatment of glaucoma and delayed gastric emptying.

Physostigma venenosum is used as a medicine in homeopathy.

Preparation of Doses: Extract of Calabar Bean, B.P.: dose, 1/4 to 1 grain. Extract of Physostigma, U.S.P.: dose, 1/8 grain. Tincture of Calabar Bean, B.P.C.: dose, 5 to 15 minims. Tincture of Physostigma, U.S.P.: dose, 15 minims. Physostigmine Eyedrops, B.P.C. Physostigmine eye ointment, B.P.C. Fluid extract, 1 to 3 drops.

Toxicology:
The main antidote to Calabar bean poisoning is atropine, which may often succeed; and the other measures are those usually employed to stimulate the circulation and respiration. Unfortunately, the antagonism between physostigmine and atropine is not perfect, and Sir Thomas Fraser has shown that in such cases there comes a time when, if the action of the two drugs be summated, death results sooner than from either alone. Thus atropine will save life after three and a half times the fatal dose of physostigmine has been taken, but will hasten the end if four or more times the fatal dose has been ingested.

Poisons and Antidotes: In case of poisoning by the beans the stomach should be evacuated and atropine injected until the pulse quickens. With poisoning by physostigmine the stomach should be washed out with 0.2 per cent of potassium permanganate and atropine and strychnine administered hypodermically.

Disclaimer:
The information presented herein is intended for educational purposes only. Individual results may vary, and before using any supplements, it is always advisable to consult with your own health care provider

Resources:
http://www.botanical.com/botanical/mgmh/c/calbea05.html
http://en.wikipedia.org/wiki/Calabar_bean

http://www.drugs.com/npp/calabar-bean.html

http://www.kilkennytocapetown.com/Updates/update28mar/update28mar.html