Aescine
Aescine, found in the horse chestnut, is a toxic coumarin glycoside which absorbs ultraviolet light, thereby making it an ideal sunscreen agent. It also reduces inflammation and is a saponin.
References
Duke, James A. Pharmacologically Active Phytochemicals. A pre-publication reference list provided by James Duke, Ph.D in 1984. Full list appears Duke's Handbook Of Medicinal Herbs. Boca Raton,Fl.: CRC Press Inc., 1985.
Schaumberg, Paul and Ferdinand Paris. Guide To Medicinal Plants. New Canaan, Conn.: Keats Publishing, 1977.
Spoerke, David G. 1979. Herbal Medications. Woodbridge Press Publishing Co. Santa Barbara, Ca.