Researches on the constitution of physostigmine. Pt. I[-II] / by Arthur H. Salway.

  • Salway, Arthur Henry.
Date:
1912-1913
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Licence: In copyright

Credit: Researches on the constitution of physostigmine. Pt. I[-II] / by Arthur H. Salway. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Cl.—Researches on the Consti't Pav Plijsample mime. 02N3, is By Arthur Hei> The constitution of physostigmine subject of considerable interest on account of the valuable thera- peutic properties which the alkaloid possesses. It has already been shown by Petit and Polonowsky {Bull. Soc. chim., 1893, [iii], 9, 1008) that physostigmine is a monacidic tertiary base, and that it also contains a CO-NHMe complex, since carbon dioxide and methylamine are eliminated on heating with aqueous potassium hydroxide. Ehrenberg {Verh. Ges. deut. Naturfor sell. Aerzte, 1893, ii, 102) independently confirmed the conclusions of Petit and Polonowsky, and also obtained from the alkaloid by the action of potassium hydroxide in the absence of air a new base, C13H18ON2, to which the name of eseroline was given. Physostigmine was therefore stated by him to be a substituted carbamide, represented by the formula (C13HlcON)NH,CO,NHMe, and the action of alkalis on the alkaloid was represented by the equation : (C13H16ON)NH-CO-NHMe + H20 = C13H16ON-NH2 + C02 + NH2Me. Eseroline is therefore, according to Ehrenberg, an amino-deriv- ative of the complex C13H16ON, but it should be pointed out that the action of alkalis on physostigmine would be equally well explained by assuming that the alkaloid is a urethane of the formula NHMeC0'0-C13H17N2, in which case eseroline would be an alcohol, CisHiyN^OH. It is well known that physostigmine absorbs oxygen rapidly in the presence of alkalis, and is converted into oxidation products known as rubreserine, eserine brown, and eserine blue respectively. Ehrenberg (Joe. cit.) has already shown that rubreserine possesses the formula Cj3Hlc02N2, and that its formation from physostigmine depends on the primary conversion of the latter into eseroline according to the following scheme: C'l5H2l°2N8 CT8H18ON2 C18H160.2N2. Phyostigmine. Eseroline. Rubreserine. Little is otherwise known, however, regarding the chemical character of eseroline and rubreserine, whilst the so-called eserine blue and eserine brown have not previously been isolated in the pure condition. In view of these facts, it seemed evident that further information regarding the constitution of physostigmine would be obtained by a complete examination of eseroline and its