Cytisus. Cytisus Laburnum, L. (Fam. Leguminosae.)—Laburnum is a small hardy tree, indigenous in the higher mountains of Europe and cultivated throughout the civilized world for its flowers, which appear early in the spring in rich pendant yellow clusters. All parts of the plants are probably poisonous. In fifty-eight boys poisoned simultaneously by the roots, the symptoms were intense sleepiness, vomiting, convulsive movements, coma, slight frothing at the mouth, and unequally dilated pupils. (M. T. G., vol. ii, 875.) In some cases the diarrhea has been severe. The convulsions have at times been markedly tetanic; wide-spread anesthesia has been noted, and also excessive mydriasis, with loss of the pupillary reflex, elevation of temperature, delirium, and cyanosis. After death there have been found erosion of the colonic mucous membrane, extreme hyperemia of the brain, and nephritis. (D. M. W., xxi, 1895.) For cases, see also previous editions of the U. S. D.; Le Mouvement Med., 1875, No. 28; Dublin Q. J., 1863, 248; M. T. G., Sept., 1862; L. L., Aug., 1870.
Husemann and Marme isolated in 1864 an alkaloid, cytisine, a white, crystalline solid, of a bitter, somewhat caustic taste, soluble in water and alcohol, but scarcely at all soluble in ether, chloroform, benzene, or carbon disulphide. The same alkaloid has been isolated from the seeds of several plants of the Papilionaceous group. A second alkaloid, laburnine, was also announced by them. (Chem. News, July 16, 1869, 36.) Partheil (A. Pharm., 1892, 448) has since studied cytisine, and gives it the formula C11H14ON2, which has been adopted by other authorities. Ferric chloride colors cytisine and its salts blood-red, which color, however, disappears on diluting with water or on addition of hydrogen dioxide. If after the addition of this latter reagent the mixture is heated gently in the water bath an intense blue color is developed. When cytisine is distilled with soda lime, pyrrol is obtained, besides a base, C9H13N, which is possibly a hydroquinoline. A. Kannerda purified crude cytisine, obtained from the seeds of Cytisus Laburnum L., by the well known shaking out process with chloroform, by distilling it in a partial vacuum. Under a pressure of 2 mm. and a temperature of 228° C. (442.4° F.), the alkaloid distils over as a colorless liquid and congeals in the receiver in the form of fine crystalline needles. It separates from absolute alcohol in the form of small transparent rhombic crystals, which have the sp. gr. 1.0046. (Ap. Ztg., July, 1900, 486.)
According to the researches of P. C. Plugge (A. Pharm., 1895), cytisine is a very widely distributed alkaloid. He has found it in eight species of the genus Cytisus, two of the genus Genista, two of the genus Sophora, two of the genus Baptisia, and in other plants. He asserts that ulexine of Gerrard, from Ulex europaeus L., sophorine of H. C. Wood, from Sophora secundiflora (Gav.) DC. (S. speciosa Benth.), and baptitoxine of von Schroeder, from Baptisia tinctoria K. Br., are identical with cytisine. Plugge also believes that the alkaloid of Euchresta Horsfieldii Benn. (fam. Leguminosae), a Javanese pea, whose seeds are used as a contra-poison by the natives, is identical with cytisine. Kobert and Kadziwillowicz (Arb. d. Pharm. Inst. Dorpat., 1888, ii) found that cytisine caused in lower animals, spinal convulsions, followed, if the dose were large enough, by paralysis, vomiting of central origin, primary stimulation, and secondary paralysis of respiration and a marked reduction in the ozonizing powers of the red corpuscles. The blood pressure was at first elevated and later depressed and there was a paralysis of the motor nerves similar to that produced by curare. Dale and Laidlaw (J. P. Ex. T., 1912, hi) find that the rise and secondary fall of the blood pressure is due to effects upon the sympathetic ganglia and that cytisine closely resembles nicotine in its physiological action. Gray (J. P. C., 1862) found laburnum to produce in man narcotic effects, and commends it in vomiting, bronchitis, whooping cough, and asthma.
Of late years several salts of cytisine have made their appearance. The hydrochloride, hydro-bromate and nitrate have all been used as diuretics and nervines in one-twentieth to one-tenth grain doses (0.003-0.006 Gm.).