Description—Good samples of the drug consist almost exclusively of entire, unopened flowerheads or capitules, which are so minute that it requires about 90 to make up the weight of one grain. In samples less pure, there is an admixture of stalks, and portions of a small pinnate leaf. The flowerheads are of an elliptic or oblong form, about ⅒ of an inch long, greenish yellow when new, brown if long kept; they grow singly, less frequently in pairs, on short stalks, and are formed of about 18 oblong, obtuse, concave scales, closely imbricated. This involucre is much narrowed at the base in consequence of the lowermost scales being considerably shorter than the rest. The capitule is sometimes associated with a few of the upper leaves of the stem, which are short, narrow, and simple. Notwithstanding its compactness, the capitule is somewhat ridged and angular,[1435] from the involuclar scales having a strong, central nerve or keel. The middle portion of each scale is covered with minute, yellow, sessile glands, which are wanting on the transparent scarious edge. The latter is marked with extremely fine striæ and is quite glabrous; in the young state the keel bears a few woolly colourless hairs, but at maturity the whole flowerhead is shining and nearly glabrous.[1436] The florets number from 3 to 5; they have (in the bud) an ovoid corolla, glandular in its lower portion, a little longer than the ovary, which is destitude of pappus.
Wormseed when rubbed in the hand exhales a powerful and agreeable odour, resembling cajuput oil and camphor; it has a bitter aromatic taste.
Chemical Composition—Wormseed yields from 1 to 2 per cent. of essential oil, having its characteristic smell and taste. The oil is slightly levogyrate and chiefly consists of the liquid C₁₀H₁₈O, accompanied by a small amount of hydrocarbon. The former has the odour of the drug, yet rather more agreeable; sp. gr. 0·913 at 20° C. It boils without decomposition at 173°-174°, but in presence of P₂O₅ or P₂S₅ abundantly yields cymol ([see p. 333]). The latter had alreadybeen observed by Völckel (1854) under the name of cinene or cynene, yet he assigned to it the formula C₁₂H₉; Hirzel (1854) called it cinæbene.
The water which distills over carries with it volatile acids of the fatty series, also angelic acid (see pp. [313], [386]).
The substance to which the remarkable action of wormseed on the human body[1437] is due is Santonin, C₁₅H₁₈O₃. It was discovered in 1830 by Kahler, an apothecary of Düsseldorf, who gave a very brief notice of it in the Archiv der Pharmacie of Brandes (xxxiv. 318). Immediately afterwards Augustus Alms, a druggist’s assistant at Penzlin in the grand duchy of Mecklenburg-Schwerin, knowing nothing of Kahler’s discovery, obtained the same substance and named it Santonin. Alms recommended it to the medical profession, pointing out that it is the anthelminthic principle of wormseed.[1438] Santonin constitutes from 1½ to 2 per cent. of the drug, but appears to diminish in quantity very considerably as the flowers open. It is easily extracted by milk of lime, for, though not an acid and but sparingly soluble in water even at a boiling heat, it is capable of combining with bases. With lime it forms then santoninate of calcium, which is readily soluble in water. On addition of hydrochloric acid, santoninic acid, C₁₅H₂₀O₄, separates, but parts with OH₂, santonin being thus immediately reproduced. Similar facts have been recorded with regard to alantic acid ([see p. 381]).
Santonin forms crystals of the orthorhombic system, melting at 170°, which are inodorous, but have a bitter taste, especially when dissolved in chloroform or alcohol.[1439] They are colourless, but when exposed to daylight, or to the blue or violet rays, but not to the other colours of the spectrum, they assume a yellow hue, and split into irregular fragments. This change, which takes place even under water, alcohol or ether, is not accompanied by any chemical alteration. This behaviour of santonin when exposed to light, resembles that of erythrocentaurin, C₂₇H₂₄O₈. The latter has been obtained by means of ether, from the alcoholic extract of Erythræa Centaurium, and of some other Gentianaceæ. Méhu (1866) has shown that the colourless crystals of that substance when exposed to sunlight, assume a brilliant red colour, without undergoing any chemical alteration. The colourless solutions of this body in chloroform or alcohol yield the original substance. Yet as to santonin, Sestini and Cannizzaro (1876) have shown, that its dilute alcoholic solution, on long exposure to sunlight, affords a compound ether of photosantonic acid, namely C₁₅H₁₃O₄(C₂H₅)₂.
Wormseed contains, in addition to the above described bodies, resin, sugar, waxy fat, salts of calcium and potassium, and malic acid; when carefully selected and dried, it yielded us 6·5 per cent. of ash, rich in silica.
Commerce—Ludwig of St. Petersburg has stated that the imports of wormseed into that city were about as follows:—In 1862, 7400 cwt.; in 1863, 10,500 cwt.; in 1864, 11,400 cwt. The drug was brought from the Kirghiz steppes by Semipalatinsk and by Orenburg.
Uses—The drug is employed exclusively for its anthelminthic properties, partly in the form of santonin. It proves of special efficacy for the dislodgement of Ascaris lumbricoides.