Berberine
Berberine is an alkaloid found in barberry, goldenseal root, and many other plants. Berberine is antibacterial and antimalarial, and is used to reduce fevers and increase the appetite. When applied externally it has astringent properties, causing tissue to contract and reducing inflammation. At certain doses it also acts as a purgative.
References
Weiner, Michael and A. Janet Weiner. 1980. Weiner's Herbal The Guide to Herb Medicine. Stein and Day, New York. 224 pp.
Windholz, Martha, Susan Budavani, et. al. 1976. The Merck Index. Merck and Co., Inc. New Jersey.