Researches on the Alkaloids of Jaborandi Leaves.
BY E. HAMACK AND H. MEYER.
In addition to pilocarpin, the authors have obtained a second alkoloid from the leaves of jaborandi (Pilocarpus pennatifolius), for which they propose the name of "jaborin." The separation of the two alkaloids depends on the facts that free jaborin is more easily soluble in ether and more sparingly soluble in water than pilocarpin, and its platinochloride more soluble in alcohol than that of the latter-alkaloid; also that the compounds of jaborin do not crystallize.
The presence of minute quantities of jaborin in pilocarpin is most easily detected by its action on a frog's heart, since jaborin exactly resembles atropin in this respect.
From analyses of pilocarpin aurochloride and platinocliloride the authors assign to the free base the composition indicated by the formula C11H16N2O2.
A curious fact was observed with regard to its aurochloride. When pilocarpin chloride is mixed with gold chloride, a crystalline precipitate is obtained consisting of C11H16N2O2HCl + AuCl3. If this is dissolved in alcohol and boiled for a time, a crystalline salt having the composition C11H16N2O2 + AuCl3, separates on cooling.
The authors are inclined to class pilocarpin among tertiary diamines. Since the physiological action of pilocarpin is analogous to that of nicotin, experiments (which proved unsuccessful) were made to ascertain if there were any relation between its composition and that of nicotin, C10H14N2. Pilocarpin might, for example, be regarded as a methyl substitution-product of nicotin, thus:
This view is supported by the fact that jaborandi leaves yield pyridin bases among other products of their decomposition, and nicotin does the same.
Trimethylamin is formed during the dry distillation of pure pilocarpin with excess of alkali, but no coniin. Also when crude pilocarpin was distilled alone no coniin could be detected, but when distilled at 160° with excess of alkali small quantities of a body identical with coniin are formed, as stated by Poehl ("Ber.," xii, 2185), due probably to some products of decomposition, possibly of jaborin.
Preparation of Jaborin.—The crude product (commercial preparation of pilocarpin, etc.) dissolved in alcohol is submitted to fractional precipitation with an alcoholic solution of platinum chloride. The first part of the precipitate which forms a hard mass, insoluble in water, is removed; the decanted liquid is again precipitated and filtered, and the solution then fully precipitated. After filtration from the precipitate, the jaborin platinochloride separates from the alcoholic solution. The salt, together with the third precipitate, is extracted with hot water and the filtrate concentrated by evaporation over sulphuric acid in a vacuum. Jaborin platinochloride is a bright yellow powder or a dark-red amorphous crumbling mass. The deeper color is due to impurities, which can be partly removed by washing with alcohol. Another method of obtaining tolerably pure jaborin is to mix the aqueous solution of the crude substance with hydrochloric acid, filter, and add mercuric chloride until a precipitate forms. On shaking and filtering, a bright yellow liquid is obtained: sulphuretted hydrogen is added to remove the mercury, and the concentrated liquid is mixed with soda solution and shaken up with ether. On evaporation, jaborin is left as a clear colorless amorphous body. Jaborin is a very strong base, which diners from pilocarpin, especially in its sparing solubility in water and more ready solubility in ether. Its salts are soluble in water and alcohol, and do not crystallize. Free jaborin volatilizes with difficulty at high temperatures. It probably belongs to the tertiary amines. The composition of jaborin is either identical with that of pilocarpin, or their empirical formulae are closely related. It is probably contained in small quantities, together with pilocarpin, in the leaves of the plant.—Jour. Chem. Soc., Dec., 1880, from Annalen.
The American Journal of Pharmacy, Vol. 53, 1881, was edited by John M. Maisch.