Betulinic acid, a naturally occurring pentacyclic triterpenoid was found in many plants. It has been isolated with considerable success from birch bark. Apart from its isolation from plants, betulinic acid is also synthesized from betulin by different methods. It exhibits broad range of biological activities such as anticancer, antimalarial, anti-HIV, antiviral and immunomodulator activity. Anticancer property of this molecule is attributed to its ability to induce apoptosis and inhibit angiogenesis. It also inhibits topoisomerase and aminopeptidase acitvity. It induces apoptosis by direct effect on mitochondria through cleavage of caspase-8 and caspase-3 and activates nuclear factor-kappa-B (NF-kappa-B), which is a key regulator of stress-induced transcriptional activation. Activation of proapoptotic mitogen-activated protein kinases (MAPKs) and generation of reactive oxygen species (ROS) also induce apoptosis in cancerous cells. Betulinic acid is found to exhibit synergistic effect with radiation therapy and cytotoxic drugs such as vincristine, doxorubicin, taxol, cisplatin etc. Betulinic acid acts as a chemosensitizer for anticancer drug treatment in chemoresistant cancer cell lines. Studies have been performed on the structure- activity relationship of betulinic acid for anticancer activity. The three-ring skeleton (A, B and C rings) and C-28 carboxylic acid are important in eliciting anticancer activity. This phytochemical constituent puts forward new areas of research and development. It would be interesting to see its potential as a potent cytotoxic agent.
Keywords: Betulinic acid, anticancer activity, apoptosis, angiogenesis, structure activity relationship
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