302. Senega. Seneka. Senega snakeroot.
BOTANICAL CHARACTERISTICS.—Stems several, from a thick and hard, knotty root-stock; leaves lanceolate, with rough margins; calyx with 3 sepals, small, greenish, and 2 larger (called wings), colored; flowers white, in a solitary, close spike.
SOURCE.—Almost all parts of the United States east of the Rocky Mountains. It is collected for market in Kentucky and in the states west and southwest of it, and in Wisconsin, and in immense quantities in northern Minnesota. This latter variety is known as northern senega. It is, as a rule, a larger root than the southern; the anatomical and structural differences between the two roots are probably very slight. Polygala alba, Nutt., inhabits Western Texas and Western Kansas, but this variety of senega is not systematically collected for the market as are the roots of Minnesota and Kentucky.
DESCRIPTION OF DRUG.—A contorted root, about 100 mm. (4 in.) long, with a knotty crown bearing numerous remnants of scaly leaves. The main root is from 5 to 10 mm. (1/5 to 2/5 in.) thick, fleshy, but void of starch. It varies in color from a light yellow to a dark brown externally; much-branched, the branches spreading, tortuous, longitudinally wrinkled, annulate near upper end; bark thickish, inclosing a porous, yellowish wood, but easily separable from it; it consists of three layers, the inner one excessively developed on one side, forming a prominent cord or keel on drying, fracture short when dry. Odor faint, sometimes wintergreen-like; taste sweetish, afterward acrid and nauseating. The liquid preparations of it have a characteristic nauseous odor.
Powder.—Characteristic elements: See Part iv, Chap. I, B.
CONSTITUENTS.—The acrid principles to which its medicinal action is entirely due, are polygalic acid, C19H30O10, and senegin, C17H26O10—two homologues. The distinction between polygalic acid and senegin is mainly one of solubility in alcohol (the former more soluble). Lead acetate precipitates polygalic acid, but does not precipitate senegin. The root also contains a fixed oil, and a small quantity of volatile oil, which is a mixture of valerianic ether and methyl salicylate, resin, malic acid, and sugar. Liquid preparations of senega are apt to become gelatinous, which is ascribed to the presence of pectin compounds; but is very likely, at least in part, due to sapogenin, generated under the influence of acids or other compounds; the jelly is rendered soluble again on the addition of an alkali. The above proximate principles are similar to the saponins. Ash, not exceeding 5 per cent.
ACTION AND USES.—A valuable stimulating expectorant, for which it is generally used; also diuretic, and in large doses emetic and cathartic. It affects the heart like digitalis. Dose: 10 to 30 gr. (0.6 to 2 Gm.).
- Fluidextractum Senegae Dose: 10 to 30 drops (0.6 to 2 mils).
- Syrupus Senegae (20 percent. of fl'ext.), Dose: 30 to 60 drops (2 to 4 mils).
- Syrupus Scillae Compositus (Fl'ext. senega 8 per cent., Fl'ext. squill 8 per cent., Tartar emetic, 0.2 per cent.), 10 to 60 drops (0.6 to 4 mils).