The Resinoid Principle of the Root of Dioscorea Villosa.
Preparation. — Make a saturated tincture of the powdered roots of Dioscorea Villosa, and filter; add the tincture to its weight of water, and carefully distil off the alcohol; the dioscorein will be left behind in the water; collect, dry, and pulverize it. It is prepared similarly to Cimicifugin, Leptandrin, Podophyllin, etc.
History. — The profession are indebted to W. S. Merrell for the preparation and introduction of this highly valuable agent; it having been discovered by him in the winter of 1852-3. It forms a light yellowish-brown powder of a faint smell, and a slightly sweetish, resinous, very bitter, disagreeable taste, with a persistent acridity which is very sensibly felt in the throat and fauces. When exposed to the atmosphere it absorbs moisture, becomes darker colored, tenacious, of a pilular consistence, and leaves a light-yellowish greasy stain on white paper in which it is kept. It has neither acid nor alkaline reactions. When first prepared it is wholly soluble in alcohol, but on keeping for a time is only partially dissolved; in this respect it resembles podophyllin and several other resinoids, which, though completely taken up by alcohol at first, become less soluble in this menstruum by age ; probably owing to an oxidizing of the resinoid by the action of the atmospheric oxygen. It is partly soluble in water, and insoluble in oil of turpentine. Ether very slightly dissolves it, and ammonia added to the ethereal mixture forms a dark-reddish turbid solution, with the ether floating on the top of a light straw color. Chloroform produces with it a dark, muddy solution, which becomes light brown on the addition of ammonia, and if permitted to stand for ten or fifteen minutes, the mixture divides into four separate layers, the upper one being clear and of a dark wine color, the next turbid and light brown, the third saponaceous and whitish-yellow, and the lower one being a clear yellowish-white liquid. By rubbing with diluted muriatic acid it forms a liquid which, on standing, throws down a yellowish-white precipitate, the supernatant liquor being clear and transparent; the same result ensues when rubbed with diluted sulphuric acid. Ammonia added to its aqueous solution forms a light straw-colored, saponaceous fluid, with a very small precipitate of a dark color. Rubbed with sulphuric acid it becomes of a dark brownish-red color, and partially dissolves ; with nitric acid, it becomes light yellowish-red ; with muriatic acid, whitish-yellow ; with acetic acid a light straw color, and partially dissolves ; ammonia or liquor potassa forms an amber color with it. Dioscorein should be kept in bottles well-stopped; if it is desired to form pills of it, exposure to the atmosphere will produce the proper tenacity for this purpose.
Properties and Uses. — Dioscorein possesses the properties of the crude root in an eminent degree, and is undoubtedly as much a specific in bilious colic, as quinia is in intermittent. In a severe case of bilious colic pronounced past hope by several physicians, four grains rubbed up with a tablespoonful of brandy afforded prompt relief, and a repetition of the dose, in about twenty minutes from the time of taking the first, effected a cure. In ordinary cases one or two grains of dioscorein may be administered every five, ten, or twenty minutes, according to the urgency of the case. In flatulence, borborygmi, etc., it may be advantageously combined with ginger, aletrin, or asclepidin ; in many forms of uterine disease its union with cimicifugin, senecin, caulophyllin, etc., will prove very useful ; and it may be combined with the extract of cornus sericea, to overcome the nausea and vomiting of pregnant females. In cramp of the stomach, or painful spasmodic affections of the bowels, a pill or powder composed of equal parts of dioscorein, caulophyllin, and viburine, will be found a remedy of great value, as well as in after-pains ; the mixture should be given in three or four-grain doses, and repeated every half hour or hour. It is strictly an Eclectic remedy of great value, and not known or employed by practitioners of other schools. Dose of dioscorein, from one to four grains, repeated as circumstances require.