The root of Rubia tinctorum, Linné.
COMMON NAMES: Madder, Dyer's madder.
Botanical Source.—Dyer's madder has a perennial, long, cylindrical root, about the thickness of a quill, branched, externally deep, reddish-brown. The stems are several in number, herbaceous, diffuse, brittle, branched, tetragonal, and very rough, with sharp hooks. The leaves are 4 to 6 in a whorl, lanceolate or oblong-lanceolate, mucronate, somewhat membraneous, with pinnated veins, 2 or 3 inches long, and nearly one-third as wide. Flowers small and yellow. Corolla rotate and 5-parted; lobes ovate-lanceolate, apiculate. Stamens 5, short; style. 2. short; anthers ovate-oblong; stigmas conical. Fruit didymous, globose, baccate, shining, and juicy (L.—Wi.).
History and Description.—Madder is a native of the Mediterranean and southern European countries, and was extensively cultivated for the use of the dyer in various parts of that continent. The drug was chiefly imported from Holland and France, but its use is now largely supplanted by that of the artificial alizarin dye-stuffs. The root is collected in the third year of the plant, is freed from its epidermis and then dried. It consists of a dark, easily separable cortex, whose epidermis is thin, and of a ligneous meditullium, which, in the fresh state, is yellow, but becomes reddish by drying. It has a feeble odor, and a bitter and astringent taste, which properties, together with its color, are communicated to alcohol or water. The microscope discovers numerous needle-shaped crystals, or raphides, in the cells of the root-bark (P.).
Chemical Composition.—The color-producing principles of madder root are chiefly alizarin (C14H8O4) and purpurin (C15H8O5), which exist in the root partly free, but mostly combined with sugar, in the form of more or less easily decomposable glucosids. Decomposition is effected through the agency of the water-soluble, nitrogenous ferment, erythrozym, when solutions of madder extract are exposed to the air (Schunck, 1851). The alizarin-glucosid is the ruberythric acid of Rochleder (1851) (rubianic acid of Schunck), and is itself probably a decomposition product of rubian (Schunck). In the formation of purpurin from the glucosid, an intermediary product is pseudo-purpurin (purpurin-carbonic acid), which also exists in the root in free condition. Upon exposure to the air, it loses carbonic acid, and becomes purpurin. Additional constituents of madder root are sugar (10 to 15 per cent), pectin, albuminous bodies, yellow xanthine of Kuhlmann (1824), and rubichloric acid of Rochleder (chlorogenine of Schunck), which is a glucosid yielding an undesirable brownish-green coloring matter. Xanthine and chlorogenine can be removed with cold water, which dissolves from dried madder a total of 55 per cent, while boiling water abstracts about 3 per cent, consisting of nearly all the valuable color-giving constituents of madder.
ALIZARIN (C14H8O4) was discovered in madder, in 1826, by Colin and Robiquet, and was obtained synthetically from the hydrocarbon, anthracene (C14H10), by Graebe and Liebermann, in 1869. According to these chemists, it is dioxyanthraquinone. Alizarin crystallizes in dark-yellow or red prisms, or in scales, is freely soluble in alcohol, ether, wood alcohol, benzol, carbon disulphide, oil of turpentine and glycerin, very little soluble in boiling water (1 in 2940). It is insoluble in cold, very little soluble in hot solution of alum, differing in this respect from purpurin. At a temperature of 237.7° C. (460° F.), it sublimes in the form of orange-colored prisms. It dissolves in caustic alkali with purple-blue color; with calcium, barium, aluminum salts, also with the salts of heavy metals, it forms insoluble colored compounds. With alumina, fixed in fabrics, it yields red and pink; with ferric salts, purple and black colors; calico impregnated with oil and alum produces, with alizarin, Turkey-red.
PURPURIN (C14H8O5) is oxyalizarin or trioxy-anthraquinone. It was formerly designated as madder-purple. It crystallizes from alcohol in red needles, is more soluble in boiling water than alizarin, and dissolves readily in hot solution of alum with cherry-red color. By heating purpurin in sealed glass tubes to about 215° C. (400° F.), it is converted into alizarin (Bolley).
As to other coloring principles of madder, e. g., munjistin (C15H8O6) and purpuro-xanthine (C14H8O4), see A. Wurtz, Amer. Jour. Pharm., 1883, p. 365; and Husemann and Hilger, Pflanzenstoffe. Also see admirable paper on madder by Dr. Crace-Calvert, Pharm. Jour. Trans., Vol. II, 1871-72, pp. 394 and 414; and by W. J. Russell, ibid., Vol. IV, 1873-74, pp. 346 and 382.
Action, Medical Uses, and Dosage.—Madder is supposed to promote the menstrual and urinary discharges, and has been recommended for such purposes by various practitioners. However, it is not in general use, as the profession lack confidence in its action. The dose is 30 grains, 3 or 4 times a day. Animals fed upon madder have their bones colored red by it.
ALIZARIN INK.—Leonhardi obtained a patent for "Alizarin Ink" which does not contain gum, is prevented from becoming moldy by its indigo and acetate of iron, and in which the sulphate of indigo prevents the tannate of iron from separating. It is prepared by digesting 24 parts of aleppo galls and 3 parts of Dutch madder with 120 parts of water. The liquid is filtered and mixed with 1.2 parts solution of indigo, 6.2 sulphate of iron, and 2 parts crude acetate of iron solution. It is said to be a superior ink.