This section is from the book "Botanic Drugs Their Materia Medica, Pharmacology and Therapeutics", by Thomas S. Blair. Also available from Amazon: Botanic Drugs, Their Materia Medica, Pharmacology and Therapeutics.
Considerable confusion exists as regards the actions of the various forms of aesculus, the horse-chestnuts and buckeyes. What is here given is not, to me, entirely satisfactory, since I find much opposing statement.
Horse-Chestnut, Aesculus hippocastanum, contains in the bark and seeds a peculiar tannin and a bitter glucosid called aesculin, an undefined and unstable substance, the most reliable specimens of which have been given in 15-grain doses in malaria. Other substances have been isolated, but they are not important. Various textbooks ascribe numerous physiologic activities to horse-chestnut, obviously based upon the Homeopathic "provings" of the drug, which are not, if based upon the American horse-chestnut, worth the paper they are printed on, for I have "proved" the drug on myself, and the Homeopathic "provers" certainly need to try again. The drug does constipate, probably from its tannin. As grown in the United States, I don't believe the drug to be narcotic in any appreciable degree; certainly I got no such results. But the tannin in it seems to be in a form peculiarly efficacious for local application in the form of ointment or suppository in the treatment of hemorrhoids. I have verified this in many cases; but believe horse-chestnut to be of very little value when administered internally.
It is not to be expected that tannin-bearing drugs, when taken by the mouth, will affect the lower bowel. See "Tannic Acid."
Ohio Buckeye, Aesculus glabra. This is a much more active species, containing an acrid and poisonous principle, also not well defined, but a glucosid with an action somewhat similar to cocculus indicus, which latter intensely stimulates the medulla and increases intestinal secretion and peristalsis, and, as well, stimulating respiration. As Ohio buckeye is said to stimulate the portal circulation in small doses, it may be due to this glucosid. Large doses have a strychnine-like action; death results from coma when the drug is taken in lethal doses. Certainly buckeye is an active drug. I have used its fluidextract in doses of 1 to 3 minims in atonic constipation with hemorrhoids, and, in several cases, quite successfully. It is also of value locally in hemorrhoids.
Red Buckeye, Aesculus parvia, is very poisonous, similarly to Ohio buckeye, but in much greater degree. In the South the seeds are used to stupefy fish, as are the seeds of cocculus, or fish berries. This species is not used in medicine. No definite statements can be made until after this poisonous glucosid has been carefully studied.