A gum-resin from Euphorbia resinifera, Berg.
ILLUSTRATION: Bentley and Trimen, Med. Plants, 240.
Botanical Source.—This leafless, cactus-like plant is a glaucous perennial growing 6 feet or more in height. Its ascending stems are fleshy and 4-angled, each side of the stem about 1 inch in width. The stems have spreading branches whose angles are clothed with divergent, horizontal stipules of a spinescent character taking the place of leaves. These are arranged in pairs and converge at the base into an ovate, somewhat triangular disc; above each pair of spines is a depressed spot indicative of a leaf-bud. The flowers, which are borne on stalks on the summits of the branches, are 3 in number, 2 of them being borne on pedicles. The branches abound in a milky juice, which exudes and concretes on the surface of the plant when it is wounded.
History.—Formerly it was not positively known from what plant this gum-resin was obtained, though Pereira believed it to be the Euphorbia canariensis, of the Canary Isles. From investigations by Berg, however, this view would seem to be erroneous, and the latter has established beyond doubt the true source of the drug, and has given us a full botanical description and figure of the plant in question, Euphorbia resinifera, Berg. It grows in Morocco, among the Atlas Mountains, and was well known to the ancients, as both Dioscorides and Pliny gave accounts of the collection of the resin on Mt. Atlas, and made notes of its extremely acrid properties (Pharmacographia). The drug is collected by making incisions into the stems, from which the milky fluid exudes and concretes on exposure to the air, incrusting the surface and particularly the spines in its downward flow. Finally, toward the latter part of the summer, it is gathered by the collectors, who are compelled to protect themselves from its irritating, acrid dust, by enveloping the mouth and nostrils with a cloth (see Euphorbia corollata for further history).
Description.—In commerce euphorbium is found in irregular, yellowish, or brownish, slightly friable tears, of a wax-like appearance, often perforated with 1 or 2 holes, united at the base, and usually mixed with the prickles of the plant and other impurities. The have hardly any odor, and that slightly aromatic, and a feeble taste, succeeded by considerable heat and persistent acrimony. Euphorbium is partially dissolved by water, forming a milk-like fluid when rubbed up with it; its best solvents are alcohol, ether, and oil of turpentine. Euphorbium must be powdered with great caution, as it excites violent sneezing, and even inflammation of the eyes. Thrown on the fire, euphorbium melts, swells, and burns with a pale flame, evolving an odor-like that of benzoic acid.
Chemical Composition.—Euphorbium, according to Henke (Archiv. der Pharm., 1886, p. 729), consists of resin soluble in ether (26.95 per cent), resin insoluble in ether (14.25), euphorbon (34.6) caoutchouc (1.1), malic acid (1.5), gum, salts (20.40), and ammonia-soluble matters (1.2). The intense acridity of the drug is due to the ether-soluble resin, which melts at from 42° to 43° C. (107.6° to 109.4° F.). The resin insoluble in ether melts between 119° and 120° C. (246.4° and 248° F.). Euphorbon (C13H22O, Flückiger; C15H24O, Hesse; C20H36O, Henke), was first obtained in an impure state by Dragendorff and Alberti, in 1864, and was four years later given its name and prepared pure by Flückiger (Wittstein's Vierteljahresschrift, 1868, p. 89). It is a crystallizable substance, fusing at 68° C. (154.4° F.), (Henke), and yields upon treatment with phosphorus pentoxide, certain hydrocarbons, as heptane (C7H16), octane (C8H18), and paraxylene (C6H4[CH3]2). It is soluble in ether, benzin, benzene, chloroform, amylic alcohol, acetone, hot alcohol, and glacial acetic acid; almost insoluble in hot water, and precipitable by tannic acid. Henke prepared it by extracting the gum with petroleum ether and purifying the crystalline euphorbone thus obtained by dissolving it in ether, adding alcohol to permanent turbidity, allowing the yellow resin to subside, evaporating the clear liquid and crystallizing from benzin. It is tasteless, of neutral reaction, dextro-rotatory, and is not affected by diluted acids nor by alkalies. A bitter principle is also present, and may easily be obtained by boiling an alcoholic extract of the gum with water. This dissolves the bitter principle together with some of the acrid resin. The existence of Buchheim's bitter euphorbic acid, obtained (1875), by evaporating the acrid resin with alcoholic caustic potash, and precipitating with a diluted acid, is doubted by Flückiger and Henke (Flückiger, Pharmacognosie, 1891).
Action, Medical Uses, and Dosage.—Emetic, cathartic, and errhine. Seldom, however, used for these properties, on account of its severity of action. Its principal use is externally as a rubefacient or vesicant. The following reparation forms an excellent counter-irritant: Take of powdered euphorbium 1/2 drachm, coarsely powdered cantharides and mezereon bark, of each, 2 drachms, rectified spirits of wine 2 1/2 fluid ounces. Mix together, digest for 8 days, then press and filter, and to the filtered tincture add, white colophony 1 ounce, white turpentine 6 drachms. With this preparation, paper or silk may be coated three separate times, by means of a soft sponge, and, when dry, forms an excellent irritating plaster for rheumatic, gouty, and neuralgic pains. Powdered euphorbium, is frequently added to the compound tar plaster to render it more active.
Related Species.—HURA, Sand-box tree. Two species of Hura, the Hura brasiliensis, Willdenow, and Hura crepitans, Linné, both of the Nat. Ord.—Euphorbiaceae, furnish medicines. The latter is indigenous to Central and South America, and to the West Indies. It is known as ajuapar. The seed capsules break with violence, scattering the seeds, which are used in Mexico under the name habilla or pepita de San Ignacio, as a drastic cathartic. They have a pleasant, sweet taste. The leaves, after being prepared in oil, are applied in rheumatism. An acrid, milky juice is obtained from the tree. This juice, as well as the seeds and bark, is emeto-cathartic, acting somewhat like the euphorbiaceous plants in general. The Hura brasiliensis is known in South America as assacou or ussacu. It differs from the preceding in having oblong, in place of ovate catkins. The bark casca de assacou, like to the first species, is acrid. The acrid principle of Hura has been named hurin. It is a crystallizable body obtained by precipitating with water an alcoholic extract of the evaporated milky juice, and dissolving the resinous matter in ether. When heated it volatilizes in acrid vapors. Nitrates and malates are likewise present. The seed integuments contain tannin, gallic acid, and coloring substance, while the kernel yields albumen, solid fatty matter, salts, and a purgative fixed oil, which alcohol dissolves. The Brazilians use it as a remedy for elephantiasis or leprosy. Even the decoction may vesicate. It is powerfully irritant to the gastro-intestinal tract, producing violent emeto-cathartic effects. It is probably ineffectual, though mitigation of the disease, but not a cure, is reported from its use.
MANCHINEEL.—The Hippomane Mancinelli, Linné, a West Indian tree possesses poisonous properties. Its fruit, resembling in color and size our common apple, is said to poison fish when placed in the water. The tree abounds in acrid, milky juice, the poisonous principle of which is volatile. Fat, resin, caoutchouc, volatile oil, gummy material, and mancinellin are, according to Ricord-Madianna, constituents of manchineel. The juice of the tree is highly irritating, causing vesication, and if in contact with the conjunctiva, producing a violent conjunctivitis. The Indians poison arrows with it; even sleeping underneath the tree is said to produce swelling of the body. Both the juice and the fruit produce inflammatory gastro-intestinal symptoms, with emeto-catharsis.