CORTEX GRANATI RADICIS.
Pomegranate-root Bark; F. Ecorce de racine de Grenadier; G. Granatwurzelrinde.
Botanical Origin—Punica Granatum L., [see page 289].
History—In addition to the particulars regarding the pomegranate tree given in the preceding article, the following which concern the drug under notice may be stated.
A decoction of the root of the pomegranate was recommended by Celsus,[1115] Dioscorides,[1116] and Pliny[1117] for the expulsion of tapeworm; but the remedy had fallen into complete oblivion, until its use among the Hindus attracted the notice of Buchanan[1118] at Calcutta about the year 1805. This physician pointed out the efficacy of the root-bark, which was further shown by Fleming and others. Pomegranate-root is known to have been long used for a similar purpose by the Chinese.[1119]
Though the medicine is admitted to be efficient, and is employed with advantage in India where it is easily procured both genuine and fresh, it is hardly ever administered in England, the extract of male-fern being generally preferred; but it has a place in several continental pharmacopœias.
Description—The bark occurs in rather thin quills or fragments, 3 to 4 inches long. Their outer surface is yellowish-grey, sometimes marked with fine longitudinal striations or reticulated wrinkles, but more often furrowed by bands of cork, running together in the thickest pieces into broad flat conchoidal scales. The inner surface, which is smooth or marked with fine striæ and is of a greyish yellow, has often strips of the tough whitish wood attached to it. The bark breaks short and granular; it has a purely astringent taste, but scarcely any odour.
Microscopic Structure—On a transverse section, the liber is seen to be the prevailing part of the cortical tissue. The former consists of alternating layers of two kinds of cells—one of them loaded with tufted crystals of oxalate of calcium, the other filled with starch granules and tannic matter. The bark is traversed by narrow medullary rays, and very large sclerenchymatous cells are scattered through the liber. Touched with a dilute solution of a persalt of iron, the bark assumes a dark blackish blue tint.
Chemical Composition—The bark contains, according to Wackenroder (1824), more than 22 per cent. of tannic acid, which Rembold (1867) has ascertained to consist for the most part of a peculiar variety called Punico-tannic Acid, C₂₀H₁₆O₁₃; when boiled with dilute sulphuric acid, it is resolved into Ellagic Acid, C₁₄H₈O₉, and sugar. Punico-tannic acid is accompanied by common tannic acid, yielding, by means of sulphuric acid, gallic acid, which appears sometimes to pre-exist in the bark. If a decoction of pomegranate bark is precipitated by acetate of lead, and the lead is separated from the filtered liquid, the latter on evaporation yields a considerable amount of mannite. This is probably the Punicin or Granatin of former observers.
The tænicide power is due, according to Tanret (1878) to Pelletierine, C₈H₁₅NO, a liquid dextrogyre alkaloid, boiling at 180° to 185° C. It can be obtained colourless by evaporating its ethereal solution in a vacuum, but in the open air becomes yellow. Pelletierine, so called in honour of Pelletier, is readily soluble in water, alcohol or chloroform, and has a somewhat aromatic odour. Several of its salts are crystallizable, yet extremely hygroscopic. The yield of the root-bark was about ½ per cent. of the alkaloid, or about 2 per cent. of crystallized sulphate from trees grown near Troyes, in the Champagne.