Calabar bean
Encyclopedia
The Calabar bean is the seed
of a leguminous plant
, Physostigma venenosum, a native of tropical Africa
, poisonous to humans. It derives the first part of 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 , a bladder, and stigma).
, climbing perennial, with the stem woody at the base, up to 2 inches (5 cm) in diameter; it has a habit like the scarlet runner, and attains a height of about 50 feet (15.2 m). The flowers, resting on axillary peduncles, are large, about an inch long, grouped in pendulous, fascicled
raceme
s pale-pink or purplish, and beautifully veined. The seed pods, which contain two or three seeds or beans, are 6 or in length; and the beans are about the size of an ordinary horse bean but much thicker, with a deep chocolate-brown color.
, a reversible cholinesterase inhibitor alkaloid
. The alkaloid physostigmine acts in effect like a nerve gas, disrupting communication between the nerves and muscles. Resulting in copius saliva, seizures, loss of control over the bladder and bowels; then, eventually, the loss of control over the respiratory system. After which, death by asphyxiation will occur.
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 Richard 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.
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 Richard Fraser
. The bean usually contains a little more than 1% of alkaloid
s. 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 anticholinergic syndrome, myasthenia gravis
, glaucoma
and delayed gastric emptying.
the last novel both for the author Agatha Christie
and her fictional detective Hercule Poirot
.
In Jane Kamensky and Jill Lepore's novel Blindspot
Edward Easton uses the Calabar bean to poison Samuel Bradstreet and to kill himself.
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
of a leguminous plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
, Physostigma venenosum, a native of tropical Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, poisonous to humans. It derives the first part of 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 , a bladder, and stigma).
Growth
The plant is a large, herbaceousHerbaceous
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...
, climbing perennial, with the stem woody at the base, up to 2 inches (5 cm) in diameter; it has a habit like the scarlet runner, and attains a height of about 50 feet (15.2 m). The flowers, resting on axillary peduncles, are large, about an inch long, grouped in pendulous, fascicled
Fascicle (botany)
In botany, a fascicle is a bundle of leaves or flowers, or of the vascular tissues that supply these organs with nutrients...
raceme
Raceme
A raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...
s pale-pink or purplish, and beautifully veined. The seed pods, which contain two or three seeds or beans, are 6 or in length; and the beans are about the size of an ordinary horse bean but much thicker, with a deep chocolate-brown color.
Toxicology
Calabar bean contains physostigminePhysostigmine
Physostigmine is a parasympathomimetic alkaloid, specifically, a reversible cholinesterase inhibitor. It occurs naturally in the Calabar bean....
, a reversible cholinesterase inhibitor alkaloid
Alkaloid
Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...
. The alkaloid physostigmine acts in effect like a nerve gas, disrupting communication between the nerves and muscles. Resulting in copius saliva, seizures, loss of control over the bladder and bowels; then, eventually, the loss of control over the respiratory system. After which, death by asphyxiation will occur.
The main antidote to Calabar bean poisoning is atropine
Atropine
Atropine is a naturally occurring tropane alkaloid extracted from deadly nightshade , Jimson weed , mandrake and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a drug with a wide variety of effects...
, which may often succeed; and the other measures are those usually employed to stimulate the circulation and respiration. Unfortunately, the antagonism
Antagonism (chemistry)
In chemistry, antagonism is a phenomenon wherein two or more agents in combination have an overall effect that is less than the sum of their individual effects....
between physostigmine
Physostigmine
Physostigmine is a parasympathomimetic alkaloid, specifically, a reversible cholinesterase inhibitor. It occurs naturally in the Calabar bean....
and atropine
Atropine
Atropine is a naturally occurring tropane alkaloid extracted from deadly nightshade , Jimson weed , mandrake and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a drug with a wide variety of effects...
is not perfect, and Sir Thomas Richard Fraser
Thomas Richard Fraser
- Life :Fraser made his studies at the University of Edinburgh and took his Ph.D. in 1862. In 1869 Fraser was a medical assistant professor at the Edinburgh Royal Infirmary. In 1877 he was a member of an arctic expedition and later in 1877 was appointed professor of medicine at the University of...
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.
Historical uses
They constitute the E-ser-e or ordeal beansTrial by ordeal
Trial by ordeal is a judicial practice by which the guilt or innocence of the accused is determined by subjecting them to an unpleasant, usually dangerous experience...
of the people of Old Calabar
Calabar
Calabar is a city in Cross River State, southeastern Nigeria. The original name for Calabar was Atakpa, from the Jukun language....
, being administered to persons accused of witchcraft
Witchcraft
Witchcraft, in historical, anthropological, religious, and mythological contexts, is the alleged use of supernatural or magical powers. A witch is a practitioner 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
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
in the year 1840; but the plant was not accurately described till 1861, and its physiological effects were investigated in 1863 by Sir Thomas Richard Fraser
Thomas Richard Fraser
- Life :Fraser made his studies at the University of Edinburgh and took his Ph.D. in 1862. In 1869 Fraser was a medical assistant professor at the Edinburgh Royal Infirmary. In 1877 he was a member of an arctic expedition and later in 1877 was appointed professor of medicine at the University of...
. The bean usually contains a little more than 1% of alkaloid
Alkaloid
Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...
s. Of these two have been identified, one called calabarine with atropine
Atropine
Atropine is a naturally occurring tropane alkaloid extracted from deadly nightshade , Jimson weed , mandrake and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a drug with a wide variety of effects...
-like effects, and the other, now a highly important drug, known as physostigmine
Physostigmine
Physostigmine is a parasympathomimetic alkaloid, specifically, a reversible cholinesterase inhibitor. It occurs naturally in the Calabar bean....
, used in the treatment of anticholinergic syndrome, myasthenia gravis
Myasthenia gravis
Myasthenia gravis is an autoimmune neuromuscular disease leading to fluctuating muscle weakness and fatiguability...
, glaucoma
Glaucoma
Glaucoma is an eye disorder in which the optic nerve suffers damage, permanently damaging vision in the affected eye and progressing to complete blindness if untreated. It is often, but not always, associated with increased pressure of the fluid in the eye...
and delayed gastric emptying.
Use in novels
Mrs. Franklin was poisoned by the Calabar bean in CurtainCurtain (novel)
Curtain: Poirot's Last Case is a work of detective fiction by Agatha Christie and first published in the UK by the Collins Crime Club in September 1975 and in the US by Dodd, Mead and Company later in the same year....
the last novel both for the author Agatha Christie
Agatha Christie
Dame Agatha Christie DBE was a British crime writer of novels, short stories, and plays. She also wrote romances under the name Mary Westmacott, but she is best remembered for her 66 detective novels and 14 short story collections , and her successful West End plays.According to...
and her fictional detective Hercule Poirot
Hercule Poirot
Hercule Poirot is a fictional Belgian detective created by Agatha Christie. Along with Miss Marple, Poirot is one of Christie's most famous and long-lived characters, appearing in 33 novels and 51 short stories published between 1920 and 1975 and set in the same era.Poirot has been portrayed on...
.
In Jane Kamensky and Jill Lepore's novel Blindspot
Blindspot
Blindspot is a fictional mutant character in the Marvel Comics Universe whose first appearance was in Rogue vol. 3 #7. She was created by Tony Bedard and Karl Moline.-Fictional character biography:...
Edward Easton uses the Calabar bean to poison Samuel Bradstreet and to kill himself.