Betulinic acid is a naturally occurring pentacyclic triterpenoid which has antiretroviral, antimalarial, and anti-inflammatory properties, as well as a more recently discovered potential as an anticancer agent, by inhibition of topoisomerase. Betulinic acid was reported as a selective inhibitor of human melanoma. Then it was demonstrated to induce apoptosis in human neuroblastoma in vitro and in vivo in model systems. Also, betulinic acid was found active against neuroectodermal and malignant brain tumors, ovarian carcinoma, in human leukemia HL-60 cells, and malignant head and neck squamous cell carcinoma SCC25 and SCC9 cell lines. In contrast, epithelial tumors, such as breast, colon, small cell lung and renal cell carcinomas, as well as T-cell leukemia cells, were completely unresponsive to treatment with betulinic acid.
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