Betulinic acid is a pentacyclic triterpene with the chemical formula C29H46(OH)COOH. It has several direct botanical sources (it was originally isolated from was the leaves of Syzigium claviflorum) but can also be chemically derived from betulin, a substance found in abundance in the outer bark of white birch trees (Betula alba). Betulinic acid has been found to selectively kill human melanoma cells while leaving healthy cells alive. For the past four decades, the incidence of melanoma has been increasing at a higher rate than any other type of cancer.
The cytotoxic potential of betulinic acid was tested using three human melanoma cell lines, MEL-1, -2, -3, and -4. The growth of all of the cell lines was inhibited significantly by treatment with betulinic acid. The effectiveness of betulinic acid against melanoma cancer cells was also tested using athymic (nude) mice. The mice were injected with human melanoma cells, and tumor size was observed for 40 days following injections of betulinic acid. The betulinic acid seemed to effectively inhibit the growth of tumors in the mice, and the mice did not suffer from drug toxicity side effects, such as weight loss.
Betulinic acid seems to work by inducing apoptosis (programmed cell death) in cancer cells. Due to its apparent specificity for melanoma cells, betulinic acid seems to be a more promising anti-cancer substance than drugs like Taxol because Taxol seems to be a more general cell poison and is not specific to cancer cells. In fact, the specificity of betulinic acid for melanoma cells is unique in comparison to the specificity of a number of
chemotherapy drugs, including camptothecin, ellipticine, mithramycin A, etoposide, vinblastine, and vincristine.
Betulinic acid has also been found to retard the progression of HIV 1 infection, which eventually leads to AIDS, by preventing the formation of
syncytia (cellular aggregates). In addition, betulinic acid has antibacterial properties and inhibits the growth of both Staphylococcus aureus and
Escherichia coli.
Betulinic acid isn't very poisonous, is relatively inexpensive, and is abundantly available from the bark of white birch trees in the form of betulin. The compound is presently undergoing preclinical development. The University of Illinois at Chicago has licensed the worldwide rights to develop betulinic acid as an anticancer treatment.
Sources:
Pisha, et al. (1995) Nature Medicine 1(10), 1046-1051.
http://www.gis.net/~dwalzer
http://www.uic.edu/depts/paff/opa/releases/2000/betulinicacid_release.html