Rabbits are killed by doses of ·1 grm. per kilo. The symptoms commence in about ten minutes after the administration, and consist of apathy and a low temperature; the breathing is much slowed. Convulsions set in suddenly before death, and the pupils become dilated. The post-mortem appearances in animals are intense redness and injection of the meninges of the cerebellum, of the medulla oblongata, and the spinal cord. Dark red blood is found in the heart, and the kidneys are hyperæmic. The intestinal mucous membrane is normal.
§ 465. Separation of Solanine from the Tissues of the Body.—Dragendorff has proved the possibility of separating solanine from animal tissues by extracting it from a poisoned pig. The best plan seems to be to extract with cold dilute sulphuric acid water, which is then made alkaline by ammonia, and shaken up with warm amyl alcohol. This readily dissolves any solanine. The peculiar property possessed by the alkaloid of gelatinising, and the play of colours with Fröhde’s reagent, may then be essayed on the solanine thus separated.
5. CYTISINE.
§ 466. The Cytisus Laburnum.—The laburnum tree, Cytisus laburnum, so common in shrubberies, is intensely poisonous. The flowers, bark, wood, seeds, and the root have all caused serious symptoms. The active principle is an alkaloid, to which the name of Cytisine has been given. The best source is the seeds. The seeds are powdered and extracted with alcohol containing hydrochloric acid, the alcohol distilled off, the residue treated with water and filtered through a wet filter to remove any fatty oil, the filtrate treated with lead acetate; and, after separating the precipitated colouring matter, made alkaline with caustic potash, and shaken with amyl alcohol. The amyl alcohol is shaken with dilute hydrochloric acid, the solution evaporated, the crude crystals of hydrochloride thus obtained treated with alcohol to remove colouring matters, and recrystallised several times from water; it then forms well-developed, colourless, transparent prisms. From the hydrochloride the free base is readily obtained.
Cytisine, C11H14N2O.—To cytisine used to be ascribed the formula C20H27N3O, but a study of the salt and new determinations appear to prove that it is identical with ulexine.[518] Cytisine is in the form of white radiating crystals, consisting, when deposited from absolute alcohol, of anhydrous prisms, which melt at from 152° to 153°. Cytisine has a strong alkaline reaction; it is soluble in water, alcohol, and chloroform, less so in benzene and amyl alcohol, almost insoluble in cold light petroleum, and insoluble in pure ether. The specific rotatory power in solution is [α]D17° = -119·57.
[518] A. W. Gerrard and W. H. Symons dispute this; they ascribe to ulexine the formula of C11H14N2O, to cytisine C20H27N3O. Ulexine is very hygroscopic, cannot be sublimed, even in a vacuum, without decomposition, and dissolves readily in chloroform; on the contrary, cytisine is not hygroscopic, sublimes completely, and is almost insoluble in chloroform, Pharm. J. (3), xx. 1017.
A. Partheil, Ber., xxiii. 3201-3203; Arch. Pharm., ccxxx. 448-498.
It is capable of sublimation in a current of hydrogen at 154·5°; the sublimate is in the form of very long needles and small leaflets; at higher temperatures it melts to a yellow oily fluid, again becoming crystalline on cooling. Cytisine is a strong base; it precipitates the earths and oxides of the heavy metals from solutions of the chlorides, and, even in the cold, expels ammonia from its combinations.