"The inner bark of Quillaja Saponaria, Molina"—(U. S. P.).
COMMON NAMES AND SYNONYM: Soap-tree bark, Soap bark; Quillaia (Pharm., 1880).
Botanical Source.—The soap-bark tree is a medium-sized tree, bearing alternate, entire, or subdenticulate, oval, or oblong leaves. The flowers are pedunculate and axillary, have no corolla, the same branch bearing both male and female flowers. Thick bark and a very hard wood are furnished by it.
History and Description.—This tree is a native of Chili, and is known as Cullay, Quillilia, Quillaja, and Soap tree. The bark is the part employed; it is rough, dark-colored externally, and very tough. It has no odor, but workmen dislike to powder it, in consequence of the irritating properties of the dust. The taste is acrid and disagreeable. Quillaja bark is said to be used in its native country for washing clothes, and removing grease spots, and in this country it is employed for cleaning delicate ribbons, garments, and wool. It depends upon saponin for its value in this respect, foaming when rubbed with water. It is also used by the natives of Chili and Peru for washing the hair, thus: Soap-tree bark, in powder, 100 parts; alcohol, 400 parts; essence of bergamot, 20 drops. Mix. Saponin is a very energetic sternutatory, and acts as an emeto-cathartic and diuretic. This tree has been introduced in Hindustan. The U.S. P. describes the bark as in "flat, large pieces, about 5 Mm. (⅕ inch) thick; outer surface brownish-white, often with small patches of brown cork attached, otherwise smooth; inner surface whitish, smooth; fracture splintery, checkered with pale-brownish bast fibers imbedded in white tissue; inodorous; taste persistently acrid; the dust very sternutatory. The infusion of quillaja foams like soap-water"—(U. S. P.). (On the microscopical appearance of powdered quillaja, see L. E. Sayre, Amer. Jour. Pharm., 1897, p. 438.)
Chemical Composition.—The foaming properties of an aqueous infusion of quillaja bark are partly due to saponin (C19H30O10, E. Stütz, 1884). It is a non-poisonous, tasteless, amorphous, white powder, and does not cause sneezing. It is readily soluble in water, insoluble in pure ether and alcohol. It is a glucosid, and is decomposed into sugar and crystallizable sapogenin, upon boiling with diluted acids. Stütz found 2 per cent of saponin in the bark. The poisonous irritant and sternutatory properties of the latter are due to amorphous quillajic acid (also C19H30O10, R. Kobert, Amer. Jour. Pharm., 1889, p. 142) and sapotoxin (Kobert and Pachorukow, 1888). Quillajic acid is insoluble in ether, quite soluble in cold alcohol and in chloroform, soluble in water. It is precipitated from solution both by neutral and basic lead acetate, while sapotoxin is precipitated only by basic lead acetate. The latter constituent is soluble in water, insoluble in ether, and soluble only in boiling alcohol. Its aqueous solution foams upon shaking. The total quantity of saponin-like bodies is about 8.8 per cent. The bark also contains small quantities of tannic acid and a bitter principle. Upon incineration, the bark yields not less than 13 per cent of ash, the wood only 1.48 per cent; the bark contains 11.5 per cent of calcium oxalate with some tartrate (Flückiger, Pharmacognosie des Pflanzenreichs, 3d ed., 1891, p. 616).
Action, Medical Uses, and Dosage.—Powdered soap bark, when inhaled, provokes violent sneezing. Internally, it acts somewhat like senega, rendering expectoration easy, while upon the gastro-intestinal tract, it does not produce irritating effects. Being less acrid than senega, it is more agreeable to administer, and may be used in infusion or syrup (fluid extract, 2 parts; syrup, 10 parts). It has been employed to quiet cough, with tenacious secretions; in chronic bronchitis, with bronchial dilatation; emphysema, etc. Dropsy is also reputed to have been cured with it. Locally, a saponaceous aqueous solution is valued for use upon the skin where soap is objectionable, to correct fetid exhalations of the axilla, feet, etc., and to remove the greasiness of the skin in treating cutaneous ulcers and eruptions. The scalp may be cleaned with it, and a tincture of it is reputed useful in alopecia. A snuff of powdered quillaja is said to be useful in coryza, and to have effected a permanent cure in chronic rhinitis. A watery solution of the dried aqueous extract is considerably used in pharmacy as an emulsifying agent for oils—castor oil, cod-liver oil, etc.—and as a froth-producer for soda-water syrups. Dose of infusion (bark℥ss to water Oj), ½ to 1 ounce, several times a day; of the syrup, flℨi to flℨij.