240 



LEGUMINOS.E 



seeds of oil palms, Elais Guineensis. E. H. Holmes called atten- 

 tion to certain specimens of calabar beans of commerce bearing a close 

 resemblance to the genuine beans. They were longer, of circular cross- 

 section, and the hilum did not extend the full length of the beans. 

 They also differ chemically, as upon touching the cotyledons with a 

 solution of potassa a permanent yellow tint was produced, and upon 

 treating the spurious article similarly a deep, almost orange, color 

 is formed, turning to a greenish hue. It has been found that the 

 ordinary test-reagents for alkaloids are so sensitive for physostigmine 



(eserine) that one one-millionth 

 part of a gram may be recognized. 

 The poisonous qualities reside in the 

 seeds, especially in the cotyledons. 

 It has been ascertained that the 

 leaves and stems are not poisonous. 



Powder. Characteristic elements : See 

 Part iv, Chap. I, B. 



CONSTITUENTS. Physostigmine, Ci 5 - 

 H 2 iN 3 O 2 (also known as eserine), 

 contracting the pupil of the eye; 

 calabarine, a tetanizing principle, 

 a derivative of physostigmine; 

 eseridine, CisH^sNaOs (producing 

 purgation); and physosterin, a 

 neutral principle closely related to 

 cholesterin. These principles are 

 soluble in alcohol. Physostigmine 

 is amorphous, tasteless, reddened by potassa, soda, and lime when 

 exposed to the air, due to absorption of oxygen. The drug sometimes 

 contains over 0.15 per cent, of the alkaloid Physostigmine. Ash, 

 not exceeding 3 per cent. 



Preparation of Physostigmine (Eserine). Treat powdered drug (mixed with 

 I per cent, tartaric acid) with water. Shake out coloring matter with ether, make 

 aqueous solution alkaline with an alkaline bicarbonate, and shake out alkaloid 

 with ether. Evaporate ethereal solution. 



Preparation of Eseridine (Calabarine). Precipitate the alkaloid from the liquid 

 from which physostigmine has been separated by lead subacetate and ammonia; 

 evaporate the filtrate, treat the residue with alcohol, precipitate with phospho- 

 tungstic acid, and decompose with baryta. It is converted into physostigmine by 

 hydrolysis. 



Preparation of Physosterin. Exhaust beans with petroleum ether and evaporate 

 solvent. 



ACTION AND USES. Physostigmine is used in medicine chiefly for three 

 purposes: as a depressant for the spinal cord; as a stimulant to the 

 intestinal muscles; and to contract the pupils. As a motor depressant 

 physostigmine is useful in the treatment of tetanus and strychnine 



FIG. 130. Calabar bean. 



