Aesculus comprises about thirteen to fifteen species of trees native to the Northern Hemisphere. Aesculus hippocastanum is the only European species, and is commonly cultivated in North America. Aesculus species are often cultivated as ornamentals, as they are attractive trees with palmately compound leaves having large, toothed leaflets. They bear numerous showy whitish flowers and large spiny or warty green fruits containing one or two large, hard, glossy brown seeds. The seeds, often called buckeyes or conkers, are traditionally collected by children and considered lucky. Preparations of almost all parts of the plant have traditionally been used medicinally for a variety of purposes. The seeds are high in starch and have been used as a foodstuff. However, all parts, including fruit husks, leaves, and seeds, contain toxic compounds, and consumption of raw seeds (at sublethal doses) causes temporary neurological symptoms. The seeds therefore require special preparation to be made edible.

Traditional uses of seed preparations included varicose veins, hemorrhoids, and other vascular problems. Oral extracts of horse chestnut seeds have been shown in multiple clinical trials to treat leg edema and chronic venous insufficiency; effectiveness is close to that of compression stockings. These products are also used to treat hemorrhoids One major active ingredient is a compound called aescin (or escin), which has been shown to have several relevant bioactivities. Several human trials have found that aescin-rich topical gels also may be effective to treat superficial vein thrombosis, diabetic microangiopathy, and bruises. There is also one small human study suggesting that aescin somewhat inhibits precipitation of the antiviral drug indinavir in urine, thus that it might have the potential to reduce painful renal side effects of that drug. Commercial extracts have, at most, slight gastrointestinal side effects (although clinical studies have not lasted longer than two months) and topical preparations have not been seen to have any side effects. However, commercial products carefully limit the content of toxic compounds; homemade preparations intended for consumption could be unsafe.

Selected References

Ball, P. W. 1968. Aesculus. P. 240 in: T. G. Tutin et al., eds. Flora Europaea, vol. 2. Cambridge University Press: Cambridge.

Burrows, G. E., and R. J. Tyrl. 2001. Toxic plants of North America. Iowa State University Press: Ames, IA.

Diehm, C., H. J. Trampisch, S. Lange, and C. Schmidt. 1996. Comparison of leg compression stocking and oral horse-chestnut seed extract therapy in patients with chronic venous insufficiency. Lancet 347:292-294.

Elias, T. S. 1987. The complete trees of North America. Gramercy Publishing Co.: New York.

Pabst, H., B. Segesser, M. Bulitta, D. Wetzel, and S. Bertram. 2001. Efficacy and tolerability of escin/diethylamine salicylate combination gels in patients with blunt injuries of the extremities. Int. J. Sports Med. 22:430-436.

Pittler, M. H., and E. Ernst. 2004. Horse chestnut seed extract for chronic venous insufficiency. Cochrane Database Syst. Rev. 2004;(2):CD003230.

Sirtori, C. R. 2001. Aescin: pharmacology, pharmacokinetics and therapeutic profile. Pharmacol. Res. 44:183-193.