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Senega. U. S. (Br.) Senega. Seneg. [Senega Snakeroot, Seneca Snakeroot]

Related entry: Polygala

"The dried roots of Polygala Senega Linné (Fam. Polygalaceae), without the presence or admixture of more than 5 per cent. of stems and other foreign matter." U. S. "Senega Root is the dried root of Polygala Senega, Linn." Br.

Senegae Radix, Br.; Rattlesnake Root, Mountain Flax, Senega or Seneca Root, Radix Polygalae Virginianae; Polygala de Virginie, Fr. Cod.; Radix Senegae, P. G.; Senegawurzel, Klapper-Schlangenwurzel, G.; Poligala Virginiana, It.; Poligala de Virginia (Raiz de), Sp.

Besides P. Senega, two other species have attracted some attention in Europe—P. amara and P. vulgaris.as remedies in chronic pectoral affections; but, as they are not natives of this country, and are never used by practitioners here, they do not merit particular notice.

A senega which was first used in Japan, and which has been referred by some writers to P. japonica, by others to P. tenuifolia, has been examined by Renter, who finds in it 0.8 per cent. of resin, traces of methyl salicylate, and 8.8 per cent. of an oil which has somewhat the odor of patchouli. For description of other species see Polygala.

Polygala Senega has a perennial branching root, from which several erect, simple, smooth, round, leafy stems annually rise, from nine inches to a foot in height. The stems are occasionally tinged with red or purple below, but are green near the top. The leaves are alternate or scattered, lanceolate, pointed, smooth, bright green on the upper surface, paler beneath, and sessile or short petiolate. The flowers are small and white, and form a close spike at the summit of the stem. The calyx is their most conspicuous part. It consists of five sepals, two of which are wing-shaped, white, and larger than the others. The corolla is small and closed. The capsules are small, much compressed, obcordate, two-valved and two-locular, with two oblong-ovate, blackish, hairy seeds, slightly longer than the lobes of the caruncle. In P. alba Nutt, the seeds are silky and about twice the length of the caruncle lobes.

Polygala Senega extends over most of the United States and Southern Canada, east of the Rocky Mountains. At one time it was largely collected in Canada and the Northeastern Atlantic states; when this supply was exhausted, Kentucky and the States West and Southwest of it we're invaded; then Wisconsin and the Northwestern States, from which with Western Canada the commerce at present derives its chief supply. There are two varieties of the plant, the typical P. Senega, the form found in the Northeastern United States, and the variety latifolia (T. and G.) which extends from Maryland and Pennsylvania to Michigan and Tennessee. This variety is distinguished by its height (from ten to twenty inches) and its very large, ovate or ovate-lanceolate leaves, which taper towards each end and attain a length of four inches. The root of commerce seems to be obtained from both varieties. It is brought into market in bales weighing from fifty to four hundred pounds. See True (Ph. Era, 1913, xlvi, p. 68).

Owing to the extensive use of senega considerable interest is manifested in the cultivation of the plant. Hood reports to have demonstrated that it can be successfully cultivated. (Vermont Sta. Rept., 1907, p. 371.) It has also been grown by the Bureau of Plant Industry, U. S. Dept. of Agriculture.

Properties.—Senega is officially described as "usually in broken pieces; when entire slenderly conical, more or less tortuous, somewhat branched, from 3 to 15 cm. in length and from 2 to 10 mm. in thickness and bearing a few rootlets; crown knotty with numerous buds and short stem-bases; externally brownish-yellow, the crown rose-tinted, longitudinally wrinkled, frequently marked by a keel; fracture short, wood pale yellow, usually eccentrically developed; odor peculiar, penetrating; taste sweetish, afterwards acrid. Under the microscope, transverse sections of Senega usually show a characteristic eccentric development of wood, the central cylinder varying in outline from elliptical or ovate to irregularly fan-shaped, and being surrounded by an unevenly developed cortex which is thickest next to the broadest strands of wood and where the wood-wedges are narrow and the medullary rays very broad, the cortical parenchyma occupies a very narrow zone of the cross-section; in older roots a corky layer of from 4 to 5 rows of tangentially elongated, light yellowish or yellowish-brown cells; outer bark of about 20 rows of cells on one side of the root and only 10 or less on the other, the cells having slightly thickened walls and containing a colorless or pale yellow, amorphous substance, which is liberated in the form of large globules on the addition of a drop of potassium hydroxide T.S.; inner bark, the cells in radial rows, consisting of parenchyma, small groups of sieve tissue and medullary rays, the latter from 1 to 3 cells wide; all the cells in this zone show a collenchymatous thickening of the walls and contain an amorphous substance similar to that found in cells of the outer bark; woody layer of tracheas with bordered pores, wood-fibers with oblique simple pores, tracheids, and medullary rays, the latter being rather indistinct and resembling the wood-fibers; tissues of the central layer of wood colored yellowish-or reddish-brown on the addition of a drop of potassium hydroxide T.S. The powder is yellowish-gray to light yellowish-brown, odor penetrating, slightly sternutatory; when examined under the microscope it exhibits a mixture of fragments of parenchyma containing oily globules and wood-fibers with tracheae; wood-fibers, non-lignified and with oblique simple pores, from 0.175 to 0.25 mm. in length; trachea? with simple and bordered pores and about 0.175 mm. in length; medullary ray cells somewhat lignified and with large simple pores. Extract 10 Gm. of powdered Senega by means of a Soxhlet apparatus, using 50 mils of ether containing 2 drops of hydrochloric acid. Continue the extraction during four or five hours and then add sufficient ether to make the liquid measure 50 mils. Take 25 mils of this solution and evaporate it on a water bath to dryness; the residue weighs not less than 0.3 Gm., and upon dissolving it in 10 mils of chloroform, transferring the solution to a test tube and adding 5 mils of sulphuric acid to form an underlying layer, a reddish-brown color is produced at the zone of contact, and the sulphuric acid shows a slightly green fluorescence after the mixture has stood for twenty-four hours. Pour 10 mils of the original ethereal solution into a beaker containing 10 mils of water and warm the mixture on a water bath until the ether has evaporated; the aqueous solution, upon filtering and adding a few drops of ferric chloride T.S., becomes a bright pinkish purple. Senega yields not more than 5 per cent. of ash." U. S.

"Greyish or brownish-yellow, slender, usually from five to ten centimetres long, with a knotty crown bearing the bases of numerous, slender, aerial stems; frequently curved or contorted, sparingly branched, keeled, sometimes transversely wrinkled. Fracture short. In transverse section, a horny translucent cortex free from starch grains and a white, often irregularly developed, wood. Characteristic odor; taste at first sweet, afterwards acrid." Br.

Holm describes the pharmacognosy of senega root and the morphology of the plant in M. R., 1907, xvi, p. 155. Hartwich has made a very interesting observation in that he has found starch occasionally present in official senega. (Apoth.-Ztg., xxvi, p. 84.) Hartwich has also described two false senegas. (S. W. P., xlvi, pp. 537 and 749.) The pharmacognosy of the drug has been well elaborated by Tunmann in Ph. Zentralh., xlix, p. 61. Muller describes and figures senega and a number of the drugs that have been used as adulterants of this drug or as occasional contaminations. (Pharm. Praxis., vii, p. 309.)

Senega root varies somewhat in appearance according to the locality from which it is derived, and local varieties are recognized in commerce. In Southern senega the roots are very small, while in Manitoba senega they are large and thick, dark in color, and often have purple markings about the crown. The official senega is often known in commerce as Southern senega, or small senega, the roots seldom attaining the size of an ordinary lead-pencil, and four to five hundred of the dried roots being required to make a pound.

Since 1870 the so-called Northern, White, False, or Large senega has been sent into the American market from Wisconsin, Minnesota, and further west. It is much larger than true senega, probably eighty to one hundred to the pound. The knot at the top of the root is from one to three inches in diameter; below it the root abruptly contracts to from half an inch to an inch in diameter; it is usually from eight to ten inches long, more fleshy and much less contorted than true senega, nearly free from small rootlets, but breaking-up below into from four to eight descending branches; very light-colored, with the ligneous portion thick and regular, and in the circular outlines of the section, with the keel rudimental or not rarely altogether absent. The taste is similar to that of true senega, but somewhat more mucilaginous and less rapidly acrid. In structure, false senega root is very -similar to the true root; it has, indeed, been asserted that there are anatomical differences between the two senegas, but O. Linde (P. J., xvi, 724) has been unable to make out any such differences. According to L. E. Sayre (A. J. P., Sept., 1897), it is not possible to distinguish the two drugs when powdered. For description of the roots of a number of species of Polygala see Flora, Jan., 1886, and D. C., 1901, 26. False Senega was thought to be the product of Polygala Boykinii Nuttall, or of P. alba Nuttall, whose habitat extends from the mountains of Texas to western British America, but Farwell (M. R., 1907, xvi, 221) believes it is from the P. Senega, as it has the characteristic keel-like ridge of the official drug. The properties of senega as well as the medicinal virtues of the root, are extracted by boiling water and by alcohol. Diluted alcohol is an excellent solvent.

Senega root was analyzed by Gehlen, Peschier of Geneva, Feneulle of Cambray, Dulon d'Astafort, Folchi, and Trommsdorff, and subsequently by Quevenne. The virtues of senega appear to reside chiefly, if not exclusively, in the acrid principles called senegin, C17H26C10, and polygalic acid, C19H30C10. These principles resemble saponin very closely and are recognized as distinct. Quevenne obtained polygalic acid by the following process: Powdered senega is exhausted by alcohol of 33°, and so much of the alcohol is distilled off as to bring the resulting tincture to the consistence of syrup. The residue is treated with ether in order to remove the fatty matter. The liquid upon standing deposits a precipitate, which is separated by filtration and is then mixed with water. To the turbid solution thus formed alcohol is added, which facilitates the production of a white precipitate, consisting chiefly of polygalic acid. The liquid is allowed to stand for several days, that the precipitate may be fully formed. The supernatant liquid being decanted, the precipitate is drained upon a filter, and, being removed while yet moist, is dissolved by the aid of heat in alcohol of 36°. The solution is boiled with purified animal charcoal, and filtered while hot. Upon cooling, it deposits the principle in question in a state of purity. Thus obtained, polygalic acid is a white powder, inodorous, and of a taste at first slight, but soon becoming pungent and acrid, and producing a very painful sensation in the throat. It is fixed, unalterable in the air, inflammable, soluble in water slowly when cold and rapidly with the aid of heat, soluble in all proportions in boiling absolute alcohol, which deposits most of it on cooling, quite insoluble in ether and in the fixed and volatile oils, and possessed of the properties of reddening litmus and neutralizing the alkalies. Quevenne found it, when given to dogs, to occasion vomiting, and much embarrassment in respiration, and in large quantities to destroy life. Dissection exhibited evidences of inflammation of the lungs, and frothy mucus was found in the stomach, esophagus, and superior portion of the trachea, showing the tendency of this substance to increase the mucous secretion, and explaining in part the beneficial influence of senega in croup. (J. P. C., xxii, 449, and xxiii, 227.) Bolley showed that this active principle was resolvable by hydrochloric acid into glucose and a peculiar substance called sapogenin. Rochleder (Chem. Cb., 1867, p. 925) confirmed this view of the identity of polygalic acid and saponin.

Christophson (J. P. C., 1874) and Schneider (A. Pharm., [3], 7, 394) have thoroughly established the existence of saponin in senega root. According to the researches of Trommsdorff and Schneider, saponin is contained solely in the bark, the woody tissues being inert. (See Quillaja.) L. Renter (A. Pharm., 1889, 309 and 452) finds that the constituents of senega root are fixed oil and resin, traces of volatile oil (a mixture of valeric ether and methyl salicylate), sugar (7 per cent.), which seems to develop to a greater extent upon standing, senegin or saponin (from 2 to 5 per cent.), yellow coloring matter, and malates. The quantity of methyl salicylate varied in different samples from 0.25 to 0.33 per cent. See also Schroeder's analysis. (A. J. P., 1896, 178.) Methyl salicylate occurs in very many, if not all, of the species of the genus Polygala. (See paper by Kremers and James, Ph. Rev., xvi.) Kain (Ph. Ztg., 1898, 562) states that he has discovered a laevorotatory glucoside distinguished from saponin by its mild taste, solubility in absolute alcohol, and in its not giving a precipitate with barium hydroxide.

Senega yields its virtues to water, cold or hot, and to boiling alcohol, and the extracts obtained by means of these liquids have the sensible properties of the root. But under the influence of heat a portion of the acrid principle unites with the coloring matter and coagulated albumen, and thus becomes insoluble in water. In forming an aqueous extract, the infusion should be prepared by percolation, as it is thus most concentrated, and consequently requires less heat in its evaporation. In preparing the infusion, the temperature of the water should not exceed 40° C. (104° F.). Experience has thoroughly proved the value of the use of an alkali in small proportion in making galenical preparations of senega, it prevents gelatinization and combines with the active principles. (See Fluidextractum Senegae)

The roots of Panax quinquefolius L., or ginseng, were at one period frequently mixed with those of senega, but are easily distinguishable by their shape and taste. The roots of Gillenia trifoliata (L.), Moench., and Asclepias Vincetoxicum L. (P. J., ix, 411), and of Triosteum perfoliatum L., are noted as occurring in commercial senega; they are readily detected by the absence of the keel-like line.

Uses.—Senega owes what therapeutic virtues it possesses to its saponins. (See Quillaia.) These by their local irritant action upon the mucous membrane of the stomach tend to cause nausea, thereby increasing the secretions of the sweat glands and especially of the bronchial glands. For this reason the drug has been used as an expectorant in various forms of bronchitis and in asthma. In overdose it is capable of acting as an irritant poison producing violent vomiting and purging. Polygalic acid may be employed in doses of from one-fourth to one grain (0.016-0.065 Gm.), administered in the form of either pill or capsule.

For a formula for its preparation, see also A. J. P., 1860, 150.

Dose, from fifteen to twenty grains (1.0-1.3 Gm.).

Off. Prep.—Infusum Senegae, Br.; Fluidextractum Senegae, U. S.; Syrupus Senegae (from Fluidextract), U. S.; Tinctura Senegae, Br.; Syrupus Scillae Compositus (from Fluidextract), U. S.; Mistura Pectoralis, Stokes (from Fluidextract), N. F.; Syrupus Cimicifugae Compositus (from Fluidextract), N.F.


The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.



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