Betulinic Acid From Birch Bark May Treat Melanoma.
The incidence of melanoma has been increasing over the past 40 years at a faster rate than that of any other type of cancer. Current treatment options for patients with metatastic melanoma are unsatisfactory. In research supported by the National Cancer Institute wherein approximately 2,500 plant-derived extracts were evaluated for their potential anti-tumor activity, researchers discovered that an extract prepared from the stem bark of an African plant, Ziziphus mauritiana, displayed selective cytotoxicity against cultured human melanoma cells. This discovery led to the isolation of betulinic acid, a pentacyclic triterpene, as the constituent responsible for the action. In follow-up in vivo studies in which betulinic acid was administered to mice carrying human melanomas, tumor growth was completely inhibited, with a complete lack of toxicity. The mode of action by which betulinic acid exerts its effect appears to be induction of apoptosis (programmed cell death).
Betulinic acid is currently undergoing preclinical development for the treatment or prevention of malignant melanoma. The compound is fairly widespread in the plant kingdom; unfortunately, the yield is low. However, betulin, a compound closely related to betulinic acid, is a major constituent of white-barked birch trees (Betula spp.). This compound can be isolated easily from white birch bark and converted to betulinic acid. These trees are found in abundance throughout the Northern Hemisphere, and a good supply of bark can be made available for the development of betulinic acid for clinical use.
[Pisha, Emily, et al. 1995. Discovery of betulinic acid as a selective inhibitor of human melanoma that functions by induction of apoptosis. Nature Medicine, Volume 1, Number 10, October: 1046-1051.]
Article copyright American Botanical Council.
By Ginger Webb