R. P. Stephenson
Sep 1, 1948
Citations
0
Influential Citations
15
Citations
Journal
British journal of pharmacology and chemotherapy
Abstract
Conessine is an alkaloid obtained from the bark and seeds of Holarrhena antidysenterica, a tree growing in India. The alkaloid has been studied by many workers (Keidel, 1878; Burn, 1914; Chopra, Gupta, David and Ghosh, 1927; Chopra, 1933; Bakhsh, 1936) who have described various properties bearing little or no relation to one another. Conessine is a typical example of the many alkaloids described in reference books of pharmacology the properties of which are difficult to remember because there is no sign of connexion between them and because they appear to be entirely fortuitous. A report from Frere Just. Gillet, S. J., missionary in the Belgian Congo, that the chewing of the leaves of the plant Holarrhena congolensis produced anaesthesia of the mucous membrane of the mouth, led Burn (1914) to examine conessine experimentally for local anaesthetic action, which he found it to possess. Further work on this action was carried out by Trevan and Boock (1927). The use of conessine as a local anaesthetic is, however, limited by the fact that when injected it causes necrosis. Two isomers of conessine, namely isoconessine and neoconessine, have been prepared by Dr. S. Siddiqui by treating conessine with sulphuric acid. Samples of conessine dihydrochloride, isoconessine hydrochloride and neoconessine hydrochloride were left with Prof. Burn by Dr. Siddiqui with the request that they should be compared with one another for local anaesthetic potency and for local irritant action. There was a possibility that one of these substances would prove as potent as conessine and not cause an inflammatory reaction when injected. The three substances have therefore been compared for their irritant action, and the method used for making this comparison will be described in a later paper. They have also been compared for local anaesthetic action. In addition these substances have been examined for other properties; several local anaesthetics are known to depress the action of acetylcholine on the rectus muscle of the frog, and de Elfo (1948) has even observed a quantitative parallelism. Dawes's work (1946) showed that many local anaesthetics had a quinidine-like action on the heart. Conessine and its isomers have therefore been examined on skeletal and on cardiac muscle. Since the results indicated a similarity to quinidine, and since de Elio (1948) had shown that quinidine had a spasmolytic action, reducing the action of acetylcholine on the intestine, conessine and its isomers have also been tested in this way.