"A gummy exudation from Astragalus gummifer, Labillardière, and from other species of Astragalus"—(U. S. P.).
COMMON NAMES AND SYNONYM: Tragacanth, Gum tragacanth; Gummi tragacantha.
Botanical Source and History.—"Tragacanth is the gummy exudation from the stems of several species of Astragalus, belonging to the subgenus Tragacantha. The plants of this group are low perennial shrubs, remarkable for their leaves having a strong, persistent, spiny petiole. As the leaves and shoots are very numerous and regular, many of the species have the singular aspect of thorny, hemispherical cushions, lying close to the ground, while others, which are those furnishing the gum, grow erect with a naked, woody stem, and somewhat resemble furze bushes. A few species occur in southwestern Europe, others are found in Greece and Turkey; but the largest number are inhabitants of the mountainous regions of Asia Minor, Syria, Armenia, Kurdistan, and Persia. The tragacanth of commerce is produced in the last-named countries"—(Pharmacographia). The same authority enumerates, among others, the following species, the list being based upon Boissier's Flora Orientalis (1872), and revised by Haussknecht, who studied the gum-yielding shrubs in their native habitat:
- Astragalus adscendens, Boissier and Haussknecht.—Mountains of southwest Persia. Yields an abundance of gum.
- Astragalus leioclados, Boissier.
- Astragalus brachycalyx, Fischer.—Mountains of Persian Kurdistan.
- Astragalus gummifer, Labillardière.—A small shrub of wide distribution, occurring on the Lebanon and Mount Hermon, in Syria; the Beryt Dagh, in Cataonia; the Arjish Dagh (Mount Argaeus), near Kaisariyeh, in central Asia Minor; and in Armenia and northern Kurdistan.
- Astragalus microcephalus, Willdenow.—From the southwest of Asia Minor to the northeast coast, and to Turkish and Russian Armenia.
- Astragalus pycnocladus, Boissier and Haussknecht.—Closely related to the preceding. High mountains of Persia. Yields gum in abundance.
- Astragalus stromatodes, Bunge.—Northern Syria. This and the next species are the chief source of so-called Aintab tragacanth.
- Astragalus kurdicus, Boissier.—Mountains of Cilicia and Cappadocia, extending to Kurdistan.
- Astragalus Parnassi, Boissier, var. cyllenea.—Northern mountains of Morea. Yields the tragacanth of Greece.
- Astragalus verus, Olivier.—Northwest Persia and Asia Minor. Probably yields some tragacanth.
Collection, Description, and Tests.—Tragacanth exudes naturally from July to September, either from wounds cut into the shrub, or from spontaneous fissures. It usually assumes the form of tortuous bands of a parchment-like appearance. Sometimes it exudes in large tears, which have more or less the vermicular form, it then has a reddish color, and is less pure. As officially described, tragacanth occurs in "narrow or broad bands, more or less curved or contorted, marked by parallel lines or ridges, white or faintly yellowish, translucent, horn-like, tough, and rendered more easily pulverizable by a beat of 50° C. (122° F.). On treating tragacanth with water, it swells, and gradually forms a gelatinous mass, which is tinged blue by iodine T.S., and the fluid portion of which is precipitated on the addition of alcohol, but is not colored blue by iodine T.S."—(U. S. P.). Solution of gum tragacanth, when dry, is more adhesive than gum Arabic.
According to Sidney H. Maltass (Amer. Jour. Pharm., 1855, p. 423), tragacanth is collected principally in Caissar, Yalavatz, Isbarta, Bourdur, and Angora. In July and August the natives clear away the earth from the lower part of the stem of the shrub, and make several longitudinal incisions in the bark with a knife. The gum exudes the whole length of the incision, and dries in flakes, and in 3 or 4 days is collected. If the weather be hot and dry, the gum is white and clean; if it be damp, with but moderate heat, the gum requires a longer time to dry, and assumes a brown or yellow tinge. When packed for exportation, the large, white, flaky or leaf gum is picked out, and the residue is sifted through a coarse sieve; what remains upon the sieve is common or sorts gum. The gum which passed through the first sieve is now resifted in a finer sieve, that which passes through being termed Sesame seed, and that remaining on the sieve, Vermicelli. All these latter varieties are carefully picked by women, who reject the impurities, and place the purer pieces with the first two qualities. Tragacanth is very liable to adulteration with Moussul gum and Caramania gum (an exudation from plum and almond trees, sometimes known as Bassora gum, Hog gum tragacanth, or Kutera gum), two inferior articles, of a dark color, and which do not occur in flaky pieces, but which are pounded into small, angular pieces after having been whitened with white lead. In English commerce, the best tragacanth is known as Syrian tragacanth. In this country, distinction is made between Aleppo and Turkey tragacanth, the latter commanding a somewhat higher price.
Chemical Composition.—Gum tragacanth, according to Giraud (Amer. Jour. Pharm., 1875, p. 329, and 1878, p. 127), consists of water (20 per cent), pectic compounds (bassorin, perhaps Frémy's pectose, 60 per cent; it is insoluble in water, but swells up when in contact with it; also called tragacanthin, adraganthin), soluble gum (pectin, not arabin [see Acacia], 8 to 10 per cent), cellulose (3 per cent), starch (2 to 8 per cent), mineral matters (3 per cent), nitrogenous matters (traces). John Ogle's results (ibid., 1889, p. 427, from Pharm. Jour. Trans.) show moisture (18.92 per cent), soluble gum (35.94 per cent), ash (2.75 per cent), and insoluble gum (42.39 per cent). No starch was found, although its non-occurrence is very rare (see Prof. Maisch, ibid., foot-note; and E. Masing, Archiv der Pharm., Vol. CXVII, 1880, p. 41). The insoluble part can be converted into water-soluble pectin by boiling the gum for 3 hours with a 1 per cent acid solution; also by long-continued boiling with water alone (Giraud). The resulting pectin is insoluble in alcohol. Non-fermentable sugar is likewise formed in this reaction. The insoluble part of gum tragacanth is dissolved with yellow color by strong alkalies. The soluble portion presents the following differences from arabin (see Acacia). It does not exhibit an acid reaction (Flückiger, 1891), does not precipitate with solution of borax, nor of ferric chloride. It is precipitated both by neutral and basic lead acetate, while acacia is precipitated by the basic lead salt only. E. Masing (loc. cit.) found the ash in 24 specimens to vary from 1.8 to 4.5 per cent; in exceptional cases (Sterculia gums etc.) it was 6.4 to 8 per cent. (For a chemical comparison of the Australian sterculia gums with tragacanth, see J. H. Maiden, Amer. Jour. Pharm., 1890, p. 26.)
Action and Medical Uses.—Tragacanth can only act as a demulcent; but on account of its insolubility, it is rarely given internally. In powder, it is used as a vehicle for active and heavy medicines, for the purpose of giving cohesion and firmness to lozenges, and to form paste, which druggists use to label their prescriptions. Tragacanth, 1 ounce; gum Arabic, white sugar, each, 2 ounces, mixed together, in very fine powder, forms an excellent paste for covering microscopic slides with paper, as it dries quickly before it can become sour or moldy. It should be made into paste only as required for use, though a paste for labelling purposes may be preserved for a considerable time by the addition of a few drops of oil of cloves, adding water, when necessary, to thin the product.
Related Gums.—(See Hog Gum.) SARCOCOLLA. The gum-resinous exudate from Penaea Sarcocolla, Linné; Penaea mucronata, Linné, and other species of Penaeae (Nat. Ord.—Penaeaceae). Shrubs of central and south Africa. The exudation, according to Dymock (1879), also comes from Bushire. The latter product is usually accompanied by fragments and seeds of a leguminous plant, probably an Astragalus. Sarcocolla consists of small, rounded, yellowish, reddish or brownish, sponge-like grains, quite friable, and often in agglutinated masses. Fine hairs are often found intermixed with it. It has no odor, except, when heated, it evolves the odor of burning sugar, but has an insipid and sweetish taste, followed by bitterish acridity; the taste has been compared to that of liquorice root. Water dissolves the gum; in alcohol it is nearly wholly soluble, the residue consisting of impurities. According to Pelletier (1834), ether separates from it a resin; from the residue, alcohol extracts a peculiar body (sarcocollin), white gummy material remaining. Sarcocollin (C13H23O6), or pure sarcocolla, constitutes about 65 per cent of the drug. It is amorphous, both bitter and sweet to the taste, and soluble in water and alcohol. It was regarded by Dr. Thompson as holding a position intermediate between gum and sugar. Sarcocolla is not now employed in medicine, but was formerly used to heal wounds, check otorrhoea, and as an application to scrofulous enlargements and chronic articular inflammations
SASSA GUM.—A gum introduced from the Orient, forming mammillated masses, or convoluted, translucent segments, of a reddish hue, and somewhat shiny surface. It resembles tragacanth in taste, except that it is also subacrid. It softens in water, swelling to 3 or 4 times its bulk, and becomes white. It does not, however, form a mucilage. Iodine colors it blue.
CASHEW GUM.—A brownish-yellow gum, which is translucent, feebly iridescent, and partially dissolved by water, is obtained from the Anacardium occidentale, Linné. It is also known as Gomme acajou.
CHERRY GUM.—Irregular and nodular masses exuded from various species of plum and cherry. It is translucent, imperfectly soluble in water, and has a brownish or amber color.
Related Species.—Astragalus boeoticus, Linné. Mediterranean basin. Seeds have been substituted for coffee.
Astragalus glycyphyllos, Linné.—Leaves and seeds diuretic.
Astragalus escapus, Linné.—Root is bitter, astringent, and mucilaginous; diuretic.
LOCO or CRAZY WEEDS.—Under these common names several western weeds have been known, and poisonous effects upon horses and cattle have been attributed to them. A small amount of an alkaloid was isolated from one of the plants, but no toxic effects were produced. Prof. J. U. Lloyd, who has studied the subject, suggests that, possibly, the poisonous effects may be due to a ferment, such as gives jequirity its virulence. The subject has not yet been settled. These plants are the Astragalus mollissimus, Torrey, west of the Mississippi, from Nebraska south to Texas, Oxytropis Lamberti, Crotalaria sagittalis, and other plants. From Lloyd's papers on Loco (Ec. Med. Jour.), we abstract the following:
"Loco yields the usual constituents of herbs. It may be safely said that, if a specimen of the plant were to be examined, in the ordinary manner, by a chemist who had no idea of its importance, he would report that it did not contain a characteristic proximate constituent. Gum, chlorophyll, fat, resin, coloring matter, mineral salts abound, and, as is usual with most plants, alkaloidal reactions. No alkaloids in abundance, none toxic at least, no toxic glucosid. Such were my experiences. The physiological investigations were, in turn, as barren of results. Neither any constituent, nor the tincture or extract of the herb, seemed to be dominated by any physiologically active agent. I became skeptical concerning even the reputed virulence of loco, and would chew the plant, and swallow the spittle. Whether it be that conditions were not favorable to my research, or that my methods were at fault, remained undetermined; loco products would not 'loco.'"
"Preparations of the loco plant and the plant in substance have no physiological effect on men, rabbits, cats, or dogs. Cattle, horses, and sheep are the animals subject to the disease, 'locoed.' Horses are the most easily affected, cattle being less subject than either horses or sheep. The principal symptoms, as manifested in the horse, are hallucination, followed by dangerous and uncontrollable mania. The muscular system is seriously impaired, the movements of the beast being uncertain and staggering, not unlike those of intoxicated beings. The animal loses the power to back. A characteristic feature in this disease is the peculiar high step taken by the animal, which often, when urged over a very small obstacle, leaps as if making an effort to get over a very high object. A prominent characteristic is the great emaciation, the body soon becoming totally devoid of fat. In the more advanced stage, the animal becomes stupid, prefers to be alone, wanders around listlessly and aimlessly, and will eat no other food but the loco, wandering from the loco to water, and from water back to loco. Any excitement brings on fits, more especially if the animal be driven through water, when it frequently becomes so exhausted as to fall helplessly into the stream, and is drowned; even a depth of 1 or 2 feet is sufficient. The mucous tissues are extremely pallid, the bowels constipated, the hair becomes rough and lusterless. The principal post-mortem changes seem to be a softening of the intestinal tract, which is infested with an enormous amount of parasites of various kinds. The intestines are, in some places, perforated, or at least so friable as to prevent handling without breaking apart in places. A constant feature in horses is a hemorrhagic floating clot in the fourth ventricle, and at the base of the brain, suspended in an abnormally large quantity of serum. All the serous cavities are filled with an excessive secretion of serum. The animal appears to perish from starvation, with constant excitement of the nervous system, but sometimes appears to suffer acute pain, causing him to expend his strength in running wildly from place to place, pawing and rolling until he falls and dies in a few minutes. Cattle, in addition to appearing wasted, seem to be stunted in their growth, so that a 4-year-old animal, affected with loco during its growth, becomes no larger than it should be at 2 years. This briefly gives the results of the disease as condensed from Bulletin No. 25 of the Colorado State Agricultural College, the subject being admirably treated by the author, David O'Brine." (For full information on this subject, consult the papers referred to.)
Baccharis coridifolia.—The South American composite, Mio Mio, exerts a deadly force upon sheep and cattle. It contains an alkaloid, baccharine, isolated by P. N. Arata (Pharm. Jour. Trans., Vol. X, 1879, p. 6).