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Alkanet

Alkanet, Anchusae Radix. Alkanna Root, Alkanet Root; Orcanette, Fr. Spanish Bugloss. Alkannawurzel, G.—This is the root of Alkanna tinctoria L., or dyers' alkanet, an herbaceous perennial plant, of the Fam. Boraginaceae, growing in the Grecian Archipelago and the south of Europe, where it is cultivated. See E. M. Holmes, P. J., 1897, p. 61. For an account of Syrian alkanet and allied plants, see Proc. A. Ph. A., 1896, 565. Alkanet, as found in commerce, is in pieces 7 to 10 cm. long, and from 5 to 15 mm. thick, somewhat twisted, consisting of a dark-red, easily separable bark, and an internal ligneous portion, which is reddish externally, whitish near the center, and composed of numerous distinct, slender, cohering fibers. As it comes to us it is usually much decayed internally, very light, and of a loose, almost spongy texture. The fresh root has a faint odor, and a bitterish, astringent taste; but when dried it is nearly inodorous and insipid. Its coloring principle, which abounds mostly in the cortical part, is soluble in alcohol, ether, and the oils, to which it imparts a deep red color, but is insoluble in water. It may be obtained by first exhausting the root with water, and then treating it with a weak solution of potassium or sodium carbonate, from which the coloring principle may be precipitated by an acid. According to Pelletier, by whom it was discovered, it possesses acid properties, forming with the alkalies and earths neutral compounds, which are of a blue color, and soluble in alcohol and ether. Its weak acid character resembles that of alizarin, to which it is chemically related, as when distilled with zinc dust it yields methyl-anthracene. It has also received the names of anchusin and alkannin. The anchusin has been extracted and studied by C. J. S. Thompson. (A. J. P., 1886, 409.) He finds it to vary in amount between 5.25 and 6.02 per cent. It is red, resin-like, insoluble in water, soluble in oils, alcohol, chloroform, and ether, and with a rich deep blue color in alkali hydroxides, the color changing again to crimson on addition of an acid. According to A. Gawalowski, the red coloring matter of alkanet root consists of two distinct bodies, the one turning blue, the other green by the action of alkalies. The first of these, alkannic acid, is extracted by ether and alcohol. The second, anchusic acid, is obtained by extraction with benzene. Both form characteristic colored salts. (Ph. Ztg., 1902, 817.) Alkanet is somewhat astringent, and was formerly used in several diseases; but it is now employed exclusively for coloring oils, ointments, and plasters, which are beautifully reddened by one-fortieth of their weight of the root. The best way to use it with this object in view is to suspend the alkanet, after tying it in a piece of flannel, in the melted fat. A fine color is obtained by previously washing the alkanet with water and then thoroughly drying it before suspending it in the fat or oil. It is said also to be used in the preparation of spurious port wine. The Oleum Hypericum, formerly much used under that title or the name Red Oil, consisted of fixed oil colored with alkanet. (... real infused oil of hypericum is red because you used fresh herb, not because you colored it with whatever. -Henriette)


The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.



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