Goldenseal Root is a very popular herb which was used extensively by Native Americans as an herbal remedy and clothing dye. It is sometimes referred to as Yellow Root in the southern U.S. Scientific research has identified several berberis alkaloids which are primarily responsible for its famed historical uses.

Goldenseal contains a compound called berberine that kills many types of bacteria in test tubes, including the ones that cause diarrhea. Goldenseal has also been shown to kill a wide range of other types of germs in test tubes, such as those that cause candida (yeast) infections and various parasites such as tapeworms and Giardia. Goldenseal may also activate white blood cells, making them more effective at fighting infection and strengthening the immune system. Goldenseal is sometimes used as an antibiotic and disinfectant, both externally and internally.

Article: http://www.umm.edu/altmed/articles/goldenseal-000252.htm