Aesculus. Horse-chestnut.—Chestnut (Aesculus Hippocastanum, L.) said to have been originally a native of Asia, but introduced about the middle of the sixteenth century into Europe, whence it has spread to this country. It is to this species that this article especially applies, though it is probable that any medicinal properties which the tree may have are shared by the other species of the genus. The seed or nut abounds in starch, but its bitter, disagreeable taste has prevented its general use as a food, although as long ago as 1856 starch was made from it in France, and recently a pleasant and nutritious article of diet is said to have been prepared by removing its bitter principle by means of alcohol. For analysis of the oil it contains, see Stillesen, Proc. A. Ph. A., 1909, lvii, p. 201. In the leaves Rochleder found quercitrin, and a bitter principle, esculin (aesculin); and in the capsules of the fruit a peculiar acid, capsulaesic acid (J. P. C., May, 1859; Aug., 1860). (For Rochleder's method of extracting esculin, see U. S. D., 18th edition; for a second process, see A. J. P., xliv, 400.) Esculin is in shining, white, prismatic crystals, inodorous, bitter, but slightly soluble in cold water, more soluble in boiling water, and very readily so in boiling alcohol and in alkaline solutions. Its solution, which is fluorescent, is precipitated by lead sub-acetate, and its formula, according to Schiff, is C15H16O9 + 1 ½ H2O. When treated with dilute sulphuric acid, it is converted into grape sugar and a substance called esculetin, C9H6O4, which is now known to be a dioxycoumarin,

C6H2(OH)2 / O - CO
. . . . . . |

Tannin is found in all parts of the tree, including the leaves as well as the bark and fruit. According to Rochleder, when pure, it is white and soluble in water, alcohol, and ether; becomes red by the absorption of oxygen; colors ferric salts green, but violet on the addition of a little alkali; fluorescent when it is in alkaline solution; in concentrated solution is precipitated, at least partially, by sulphuric, hydrochloric, and metaphosphoric acids, but not by acetic acid, and forms also, with potassium and sodium sulphites and ammonium sulphide, precipitates which are readily dissolved by dilute acetic acid. (J. P. C., Jan., 1868, 72.)

The powdered kernel of the nut is a sternutatory. The extract of the wood has been used in dyeing silk black. The fixed oil, extracted from the kernels by ether, has been employed in France as a topical remedy in rheumatism; and the bark as an antiperiodic in doses of half an ounce (16 Gm.) in the twenty-four hours, given in the form of decoction. The flowers are stated to contain quercitrin. In the United States a decoction of the leaves is popularly employed for whooping cough, and to the seeds themselves, when "carried in the pocket of the patient," is attributed the marvellous property of curing hemorrhoids, rheumatism, etc. Esculin has also been administered in malarial disorders, in fifteen-grain (1 Gm.) doses repeated once during the intermissions. (Ann. Ther., 1859, 1860.) The glucoside esculin has the property, like other fluorescent substances, of absorbing ultra violet rays which are then gradually given off. Because of these properties, it is used on the one hand, as a protective against the effects of sunlight and on the other as a means of continuing the effect of heliotherapy. Thus Freund has found it useful not only against sunburn, but as a prophylactic against snow blindness (Zeit. f. Neuere Physikal. Med., 1908, ii), and Graham (L. L., 1905, ii, p. 1769) recommends it in the Finsen light treatment of lupus vulgaris and similar conditions. For this purpose he injected five minims (0.3 mil) of a 2 or 3 per cent. solution immediately beneath the skin in the region to be treated by the light. Under the name of zeozon and ultra-zeozon there are upon the market pastes whose exact compositions are not stated but which are claimed to contain oxy-derivatives of esculin.

The fruit of the Aesculus pavia L., or Red Buckeye of the Southern United States, is said to be an active convulsant. E. C. Batchelor (A. J. P., xlv, 144) found in the cotyledons of the seeds about 2 ½ per cent. of a peculiar glucoside. Aesculus glabra Willd., the Ohio Buckeye, is asserted to be useful in portal congestion. (N. P., ii, 21.)

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