Calabar Bean

Four species of perennial climbers belong to this W African genus, which is placed in the family Papilionaceae by some botanists. Before its adoption by Western medicine, Physostigma venenosum was notorious as the plant used in the "ordeal by poison" in the Calabar Province of Nigeria. In this ritual, an accused person drinks some solution of poisonous beans, dying if guilty and apparently surviving if innocent. The success of the method may be based on the probability that innocent people will tend to gulp the entire drink, causing vomiting and expulsion of toxins, while the guilty are perhaps more likely to sip cautiously and thereby ingest more poison. Physostigma venenosum contains alkaloids, of which the most important is physostigmine (eserine), which influences the parasympathetic nervous system. It is mainly used in eye drops to reduce pressure on the eyeball, and as an antidote to atropine (See, Deadly Nightshade, Atropa belladona). Another alkaloid, calabarine, has opposite effects. Extracts of whole seeds differ in effects from isolated alkaloids.

This very poisonous plant, native to Africa, earned the name "ordeal bean" when natives forced prisoners accused of witchcraft to eat its seeds. If the prisoner vomited within half an hour, he was considered innocent; if he died, he was found guilty. Used primarily to treat glaucoma, calabar bean contains physostigmine, which relieves pressure within the eyeballl

Evergreen climber with trifoliate, ovate, pointed leaves, 16cm (6in) long and 10cm (4in) wide. Pink-purple pea flowers, about 2.5cm (1in) long, are produced in spring, followed by pods to 16cm (6in) long, containing 2-3 brown-black seeds, 3cm (1¼in) long.


Common Name:
Calabar Bean
Other Names:
Chop Nut, Esere bean, Ordeal bean
Botanical Name:
Physostigma venenosum
Genus:
Physostigma
Family:
Fabaceae
Native Location:
Tropical W. Africa
Cultivation:
Rich, well-drained soil in sun.
Propagation:
By seed sown when ripe.
Harvest:
Seeds are collected when ripe, mainly in the rainy season, and dried for use in decoctions and for extractions of alkaloids.
Height:
15m (50ft)
Width:
Indefinite
Hardiness:
Min. 15-18°C (59-64°F)
Parts Used:
Seeds (with outer coat removed)
Properties:
A narcotic herb that depresses the central nervous system, mimics the parasympathetic nervous system, contracts the pupil of the eye, raises blood pressure, and stimulates peristalsis.
Medicinal Uses:
As physostigmine, internally for neuromuscular diseases (notably myasthenia gravis), and post-operative constipation; externally as eye drops (especially for glaucoma). Formerly used in the treatment of tetanus, epilepsy, and rheumatism.
To treat glaucoma; to stimulate the peristaltic movements that move food through the digestive tract; as an antidote for poison.
Typical Dose:
A typical dose of calabar bean in the form of physostigmine eye drops may range from 1 to 2 drops taken three times daily.
Possible Side Effects:
Calabar bean is very poisonous, and can even be poisonous as eyedrops when they are inappropriately administered. Symptoms of poisoning may include nausea, diarrhea, vomiting, salivation, exhaustion, chills, dizziness, and muscle paralysis.
Drug Interactions:
Taking calabar bean with these drugs may interfere with the action of the drugs:
Atropine, (Isopto Atropine, Sal-Tropine) Benztropine, (Apo-Benztropine, Cogentin) Clidinium and Chlordiazepoxide, (Apo-Chlorax, Librax) Cyclopentolate, (Cyclogyl, Cylate)
Dicyclomine, (Bentyl, Lomine) Glycopyrrolate, (Robinul, Robinul Forte) Homatropine, (Isopto Homatropine) Hyoscyamine, (Hyosine, Levsin)
Hyoscyamine, Atropine, Scopolamine, and Phenobarbital, (Donnatal, Donnatal Extentabs) Ipratropium, (Atrovent, Nu-Ipratropium) Oxitropium, (Oxivent, Tersigat) Prifinium, (Padrin, Riabel)
Procyclidine, (Kemadrin, Procyclid) Propantheline, (Propanthel) Scopolamine, (Scopace, Transderm Scop) Tiotropium, (Spiriva)
Tolterodine, (Detrol, Detrol LA)
Trihexyphenidyl, (Artane)
 Trimethobenzamide, (Tigan)
Disease Effects:
May exacerbate or interfere with the treatment of asthma, diabetes, cardiovascular disease, Parkinson's disease, gangrene, slow heart rate, and intestinal obstructions.
Warning:
Excess causes muscular weakness, respiratory failure, and cardiac arrest. For use by qualified practitioners only.
Bibliography:
Encyclopedia of Herbs by Deni Brown Copyright © 1995, 2001 Dorling Kindersley Limited Pg 314
The Essential Herb-Drug-Vitamin Interaction Guide by Geo. T. Grossberg,MD and Barry Fox,PhD Copyright©2007 Barry Fox,PhD. Pp.113-114