Elecampane was formerly cultivated in gardens as a medicinal and culinary plant, and in this manner has wandered to North America. In Holland and some parts of England and Switzerland, it is cultivated on a somewhat larger scale, most largely probably near Cölleda ([see p. 377]).
History—The plant was known to the ancient writers on agriculture and natural history, and even the Roman poets were acquainted with it, and mention Inula as affording a root used both as a medicine and a condiment. Vegetius Renatus, about the beginning of the 5th century, calls it Inula Campana, and St. Isidore in the beginning of the 7th names it as Inula, adding—“quam Alam rustici vocant.” It is frequently mentioned in the Anglo-Saxon writings on medicine current in England prior to the Norman Conquest; it is also the “marchalan” of the Welsh Physicians[1413] of the 13th century and was generally well known during the middle ages. Not only was its root much employed as a medicine, but it was also candied and eaten as a sweetmeat.
Description—For pharmaceutical use, the root is taken from plants two or three years old; when more advanced, it becomes too woody. The principle mass of the root is a very thick short crown, dividing below into several fleshy branches of which the larger are an inch or two in diameter, covered with a pale yellow bark, internally whitish, and juicy. The smaller roots are dried entire; the larger are variously sliced, which occasions them to curl up irregularly. When dried, they are of a light grey, brittle, horny, smooth-fractured. Cut transversely the young root exhibits an indistinct radiate structure, with a somewhat darker cambial zone separating the thick bark from the woody nucleus. The pith is not sharply defined, and is often porous and hollow. In the older roots the bark is relatively much thinner, and the internal substance is nearly uniform. Elecampane root has a weak aromatic odour suggestive of orris and camphor, and a slightly bitter, not unpleasant, aromatic taste.
Microscopic Structure—The medullary rays, both of the woody column and the inner part of the bark (endophlœum), exhibit large balsam-ducts. In the fresh root they contain an aromatic liquid, which as it dries deposits crystals of helenin, probably derived from the essential oil. The parenchymatous cells of the drug are loaded with inulin in the form of splinter-like fragments, devoid of any peculiar structure.
Chemical Composition—It was observed by Le Febvre, as early as 1660, that when the root of elecampane is subjected to distillation with water a crystallizable substance collects in the head of the receiver from which it speedily passes on as the operation proceeds. Similar crystals may also be observed after carefully heating a thin slice of the root, and are even found as a natural efflorescence on the surface of root that has been long kept. They can be extracted from the root by means of alcohol and precipitated with water. Kallen (1874, 1876) showed that the crystals chiefly consist of the anhydride, C₁₅H₂₀O₂, of alantic acid, melting at 66° C. The anhydride, which is very little aromatic, can easily be sublimed, although it begins to boil only at 275°, yet not without decomposition. Alantic anhydride dissolves in caustic lye, but on saturating the solution with an acid, alantic acid, C₁₅H₂₂O₃, separates. It is not present in the root.
The anhydride is accompanied by a small quantity of Helenin, C₆H₈O, and Alantcamphor (i.e. Elecampane-camphor). The crystals of helenin have a slightly (?) bitterish taste, but no odour, and melt at 110°. The camphor, occurring in but very small amount, has not yet been analyzed; it agrees probably with the formula C₁₀H₁₆O; it melts at 64° C., and in taste and smell is suggestive of peppermint. It is very difficult entirely to remove helenin from alantcamphor, these substances being soluble to nearly the same extent in alcohol or ether. By distilling the second of them with pentasulphide of phosphorus, Cymene, C₁₀H₁₄, was obtained.
By distilling the root under notice with water, the alantic anhydride is chiefly obtained, but impregnated with Alantol, C₁₀H₁₆O (probably). The latter can be removed from the crystals by pressing them between folds of bibulous paper. On submitting this again to distillation, alantol is obtained as an aromatic liquid, boiling at 200°.
The substance most abundantly contained in elecampane root is Inulin, discovered in it by Valentine Rose at Berlin in 1804. It has the same composition as starch, C₆H₁₀O₅, but stands to a certain extent in opposition to that substance, which it replaces in the root-system of Compositæ. In living plants, inulin is dissolved in the watery juice, and on drying is deposited within the cells in amorphous masses, which in polarized light are inactive, and are not coloured by iodine. There are various other characters, by which inulin differs from starch. Thus for instance, inulin readily dissolves in about 3 parts of boiling water; the solution is perfectly clear and fluid, not paste-like; but on cooling deposits nearly all the inulin. The solution is levogyre and is easily transformed into uncrystallizable sugar. With nitric acid, inulin affords no explosive compound as starch does.
Sachs showed in 1864 that by immersing the roots of elecampane, or Dahlia variabilis or of many other perennial Compositæ, in alcohol or glycerin, inulin may be precipitated in a crystalline form. Its globular aggregates of needle-shaped crystals (“sphæro-crystals”) then exhibit under the polarizing microscope a cross similar to that displayed by starch grains.
The amount of inulin varies according to the season, but is most abundant in the autumn. Of the various sources for it, the richest appears to be elecampane. Dragendorff, who has made it the subject of a very exhaustive treatise,[1414] obtained from the root in October not less than 44 per cent., but in spring only 19 per cent.