Fig. 134. Aesculus hippocastanum. Photo: Aesculus 2. Related entry: Aesculus.—Ohio Buckeye
(This is not the same plant as chestnut).

The bark and fruit of Aesculus Hippocastanum, Linné.
Nat. Ord.—Sapindaceae.
COMMON NAME: Horse-chestnut.

Botanical Source.—The Aesculus Hippocastanum is a beautiful middle-sized, round-headed tree, 50 or 60 feet in height, with many branches, a rugose, tawny bark, and a white, not very firm wood. The leaves are opposite, digitate, long-stalked, and consist of 7 obovate-lanceolate, acuminate, bright-green, coarsely and irregularly serrated leaflets which diminish in size from the center. The flowers, which are pink-colored and white, are borne in terminal thyrses, or pyramidal racemes. The corolla is spreading and composed of 5 oblong, unguiculate, fringed, wavy petals, with a small reddish spot above each claw. The calyx is 5-toothed, bright-green, and campanulate. The stamens are 7 in number, and support reddish-brown, oblong anthers. The fruit is a prickly, thick, and tough capsule, 3-valved, 1 to 3-celled, with usually 2 large, deep chestnut-brown seeds, and a large broad space forming a hilum.

Description.—THE BARK. Horse-chestnut bark is of a gray color externally, showing leaf scars and wart-like excrescences sparingly distributed. The internal surface is whitish and smooth. The bark is thin, and throughout its internal structure presents a brown or brownish color. The inner bark has a rough, bitter taste, and is nearly odorless; and is tough and fibrous on fracture. It yields its properties to water and diluted alcohol. The aqueous infusion is bitter, fawn-colored, and non-astringent. Gelatin separates its tannic acid; iron gives a green precipitate; infusion of galls and tartar-emetic produce no effect upon it.

THE NUT, when dry, is subglobular, compressed, from 1 to 1 ½ inches in diameter, with a shining, chestnut-brown testa, marked by a reddish or yellowish-gray hilum, nearly an inch in diameter. In the middle of the hilum is a smaller spot, in the center of which is a slightly roughened elevation. Passing from the hilum around to the opposite surface may be observed an elevated ridge terminating in a bulbous extremity, and resting in a horseshoe-shaped depression. The surface of the nut is slightly corrugated. The internal portion is starchy, yellowish-white in color, and has an unpleasant, bitter taste. The nut has a slight, peculiar odor.

History.—Horse-chestnut is indigenous to certain parts of southern Asia (Persia, northern India), from whence it was conveyed into Europe. It is now common to many parts of the United States, where it grows rapidly, blossoming from April to July, and maturing its fruits in the autumnal months. It is extensively cultivated for shade and ornamentation in gardens and along sidewalks.

Chemical Composition.—All parts of the plant, especially the bark of the root, trunk, and branches, and the testa of the seeds, contain a peculiar tannic acid, which forms an uncrystallizable, nearly colorless mass, whose solutions turn red-brown when exposed to the air. Heating with diluted mineral acids to the temperature of boiling water produces a red phlobaphene, a substance which also occurs ready-formed in the bark and the leaves of the tree (Rochleder). Aesculin (C15H16O9), discovered by Canzoneri and first obtained pure by Minor (1831), is a faintly bitter glucosid occurring principally in the bark, also in the testa of the seeds, but not in the leaves (F. O. Ray, Amer. Jour. Pharm., 1886, p. 409). From 2 to 3 per cent have been obtained from the bark. It is a white, microcrystalline powder, soluble in 672 parts of cold and 12.5 parts of boiling water, and in 24 parts of boiling alcohol, but insoluble in absolute ether. Aesculin is distinguished by the blue fluorescence it displays in aqueous, but more markedly in alkaline solution. This glucosid is easily decomposed into its constituents, if it be heated above its melting point, 160° C. (320° F.), and also by the action of the ferment emulsin (see Amygdalus), or when boiling it with diluted acids, when it is decomposed into dextrose and aesculetin (C9H6O4). The latter substance, which is also to be found in the bark, is a dioxy-coumarin (C6H2[OH]2CH:CH.CO.O), and an isomer to daphnetin, a derivative of certain species of Daphne. Aesculin has been repeatedly demonstrated to be different from gelsemic acid, with which it was at one time supposed to be identical (see Gelsemium).

A crystallizable, bitter glucosid, argyraescin (C27H42O12), found by Rochleder in the cotyledons of the seeds, occurs most largely shortly before maturity. A yellow coloring matter (queraescitrin of Rochleder), occurs in the leaves of horse-chestnut, as well as in the cotyledons of the seeds, and especially in the flowers. More recently N. Rudolph (see Amer. Jour. Pharm., 1894, p. 35), established its chemical relationship to other quercitrin-like bodies, and gave it the formula C21H22O12, while quercitrin (of quercitrin bark), was found to contain 1 molecule less of water. Boiling with diluted acids decomposes the horse-chestnut quercitrin into isodulcite (C6H14O6), and quercetin (C15H10O7).

A variety of other substances, such as aescic and capsulaescic acids, telaescin, fraxin, etc., mostly intermediary products in the development of the different parts of the plant, have been isolated by Rochleder, for which see details in Husemann and Hilger, Pflanzenstoffe, p. 870. Saponin (aphrodaescin of Rochleder, 1958), is also a constituent of the seeds, and the latter have long been known to be useful in powder form for washing purposes and as a sternutatory (see Pharm. Centralh., 1892, p. 687, and 1896, p. 163). A fatty oil (Oleum Hippocastani), has been obtained from the seeds in the amount of 0.1 per cent. It is of a rich yellow color, has a specific gravity of 0.927, and solidifies at a temperature of +1.25° C. (34.3° F.). The seeds also contain starch, and on this account attempts have been made to utilize horse-chestnut seeds as a food material, but these efforts have not met with success, owing to the difficulty of economically removing saponin from the seeds (see P. Soltsien, Chem. Zeitung, 1891, p. 1374).

In the seeds of Aesculus Pavia, Linné, the Red buckeye of the southern states, E. C. Batchelor (Amer. Jour. Pharm., 1873, p. 145), found a poisonous glucosid, insoluble in ether and chloroform, soluble in hot alcohol, and freely soluble in cold water; this solution froths upon being shaken. The principle is not identical with the argyraescin and the aphrodaescin of Rochleder.

Action, Medical Uses, and Dosage.—Undoubtedly horse-chestnut acts upon the human system very much after the manner of buckeye (Aesculus glabra). By some, however, its power over the circulation is thought to be more pronounced, particularly its control over the portal vessels. The virtues formerly ascribed to the bark and nut are as follows: Horse-chestnut bark is tonic, astringent, febrifuge, narcotic, and antiseptic. In intermittent fever the bark has effected cures when given in doses of a teaspoonful 4 or 6 times a day. Ten grains of the powder of the rinds of the nuts have been asserted to be equivalent in narcotic power to three grains of opium. This claim, however, requires substantiation. Gangrenous and ill-conditioned ulcers have-been benefited by a strong infusion of the bark. The whitish, central part of the nuts, when in powder, has been recommended as a sternutatory in some cases of ophthalmia and headache. The oil of horse-chestnuts is considered in Europe a valuable local application in neuralgic and rheumatic affections; it is made by exhausting the powdered horse-chestnut in ether, filtering and evaporating. Aesculin, in doses of from 5 to 80 grains, repeated 2 or 3 times a day, has proved beneficial in periodical febrile affections, and in neuralgia of the internal viscera. Of all the uses formerly made of hippocastanum, only the latter is recognized to-day, its power of controlling neuralgia of the viscera, and then only in cases of abdominal plethora. Specific medication has taught us that it is a remedy, not for active conditions, but for congestion and engorgement. It is indicated in general by capillary engorgement—a condition of stasis—with vascular fullness and sense of soreness, throbbing, and malaise all over the body. An uneasy, full, aching pain in the hepatic region is also an indication. Rectal disorders, such as rectal irritation and hemorrhoids, with marked congestion and a sense of constriction, as if closing spasmodically upon some foreign body, with itching, heat, pain, aching, or simple uneasiness, are fields in which hippocastanum exerts a specific influence. The pile-tumors are purple, large, do not bleed as a rule, but there is a sense of fullness, or spasm of the parts, and a free diarrhoea may be present. Not only does it relieve such rectal complaints, but cures disorders hinging upon them, such as rectal neuralgia, proctitis, etc., and the reflexes induced by them, proceeding from the rectal involvement. Among these reflex manifestations may be mentioned dyspnoea, asthmatic seizures, dizziness, headache, backache, and disturbed gastric functions amounting to veritable forms of dyspepsia. These conditions pass away when hippocastanum overcomes the rectal difficulties. Dose of specific horse-chestnut (prepared from the nut only), from ¼ to 5 minims in water every 1 to 3 hours.

Specific Indications and Uses.—Visceral neuralgia, due to congestion; soreness of the whole body, with vascular fullness, throbbing, and general malaise; throbbing, fullness, and aching in the hepatic region; rectal uneasiness with burning or aching pain; sense of constriction, with itching; large, purple pile-tumors; uneasy sensations and reflex disturbances depending upon hemorrhoids or rectal vascular engorgement.

King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.