Alkaloids of Angustura Bark.
BY KOERNER AND C. BOEHRINGER.
In this preliminary notice the authors, after some historical details as to the introduction of the bark, state that it contains aromatic substances and several alkaloids, the amount of the latter varying in different specimens from 0.8 to 1 per cent. The alkaloids are mostly in the free state, and may be extracted directly from the bark by means of ether. After the ethereal extract has been washed with dilute potash solution, the addition of oxalic acid or dilute sulphuric acid gives a yellow crystalline precipitate of the corresponding salt of one of the alkaloids, cusparine, whilst other alkaloidal salts remain in solution.
The precipitated cusparine salt is moderately soluble in boiling alcohol, and, on cooling, crystallizes out in slender needles of a magnificent greenish yellow; this color is not removed by repeated crystallization, or by treatment with animal charcoal, and other salts of the alkaloid, obtained from the yellow precipitate by decomposition, are also intensely yellow. If, however, the free cusparine, C19H17NO3, obtained from these colored salts, is crystallized several times from light petroleum, and then reconverted into the salt, this is found to be colorless. The author has been unable to ascertain the cause of this yellow coloration. The alkaloid crystallizes from light petroleum in tufts of slender needles melting at 92°; it is moderately soluble in ether, more readily in alcohol. The sulphate, oxalate and hydrochloride of the base are but sparingly soluble in water; the acetate is much more soluble, but the solution is decomposed if largely diluted; the tartrate dissolves readily. The platinochloride was obtained as an orange-yellow crystalline precipitate.
When treated with potassium hydroxide, cusparine splits up, yielding a new alkaloid and the potassium salt of an acid which seems to be an aromatic derivative; the acid is sparingly soluble and crystallizes readily. The alkaloid crystallizes from alcohol, in which it is very sparingly soluble, in minute, very brilliant, colorless needles; it decomposes at 250° without melting. An attempt to decompose the cusparine in a similar manner by the action of hydrochloric acid failed, as it began to carbonize even at 100°.
In the mother-liquors from which the cusparine was originally precipitated as sulphate or oxalate, another alkaloid is found, to which the authors have given the name galipeine, C20H21NO3. The free base crystallizes from light petroleum in white needles melting at 115.5°. It may be obtained in well-formed transparent prisms from its solution in ether or alcohol. All the salts of this alkaloid are more soluble than those of cusparine; several of them are of a magnificent greenish yellow like uranium salts. The sulphate crystallizes in large prisms with 7 mols. H2O, which it loses in part on exposure to the air; it melts at 15°, and at 100° undergoes decomposition, yielding the sulphate of another alkaloid and a crystalline nitrogenous substance which melts at 196°. The platinochloride crystallizes in prisms with a triangular base.
Besides cusparine and galipeine, the authors have found another alkaloid which melts at 180°, and is very sparingly soluble in ether. It crystallizes from alcohol and furnishes salts, the solutions of which have a blue fluorescence.
The property these alkaloids have of being transformed into other alkaloids with simultaneous formation of acids, is interesting, and may throw some light on the constitution of vegetable alkaloids in general.—Jour. Chem. Soc., March, 1884, p. 341, from Gazzetta, vol. 13.