Specification & Spread
Calabar bean seeds — semina physostigmatis (faba calabarica)
Calabar bean — physostigma venenosum bulf.
Bean family — fabaceae.
It is a tropical winding liana with thick cylindrical stems up to 15 m long.
The leaves are with stipules, alternate, trifoliate; the leaves are 7–15 cm long, ovoid, with a long, acuminate tip, bare.
The flowers are bright red in the drooping loose racemes up to 15 cm long.
The fruit is a dark brown bean 10-18 cm long, containing 2-4 seeds; outside the bean flaps are with mesh veins
Naturally it grows in tropical forests of West Africa, especially around the Gulf of Guinea. It was first found on the Calabar coast, with which the name is connected.
The chemical composition of Calabar bean
The seeds contain the sum of the indole group alkaloids.
The main alkaloid is physostigmine (ezerin).
The content of physostigmine is about 1.5%.
Harvesting and storage of raw materials
The seeds are harvested after it ripens.
External signs of raw materials
The seeds are reniform-oval, slightly compressed from the sides, about 3 cm long and 2 cm wide, almost black, shiny; the raphe spreads along a convex edge in a wide furrow.
The rind is hard, woody. The cotyledons are dense, white.
Properties and application
Physostigmine is a reversible anticholinesterase agent.
It causes miosis (contraction) of the pupil and lowers intraocular pressure.
It is an atropine antagonist.
«Physostigmine salicylate» is mainly used in ophthalmology:
- for constriction of the pupil and
- lowering intraocular pressure in glaucoma.
Less commonly, physostigmine is used for intestinal and bladder paresis, and for neuromuscular diseases.
Calabar beans are very poisonous and were used before by African tribes as «judging beans» called «ezer». A person suspected of being killed or another crime was given to drink a decoction of herbs, which included Calabar bean. According to this «court of God», if a person remained alive, the charge was dropped from him, and if he died, the crime was considered proven.
Calabar bean seeds were brought to Europe in 1850.
In diseases associated with hyperfunction of cholinergic structures: in epilepsy, hyperkinesis, bronchial asthma, angina pectoris and bradycardia.