Inhibition of tumor progression by naturally occurring terpenoids

CONTEXT: Cancer is a major public health problem in India and many other parts of the world. Its two main characteristics are uncontrolled cell growth and metastasis. Natural products represent a rich source of compounds that have found many applications in various fields of medicines and therapy including cancer therapy. Effective ingredients in several plant-derived medicinal extracts are terpenoid compounds and many terpenes have biological activities and are used for the treatment of human diseases. OBJECTIVES: This review attempted to collect all available published scientific literature of eight naturally occurring terpenoids and their effect on inhibition of tumor progression. METHODS: The present review is about eight potent naturally occurring terpenoids that have been studied for their pharmacological properties in our lab and this review includes 130 references compiled from all major databases. RESULTS: Literature survey revealed that triterpenoids, such as glycyrrhizic acid, ursolic acid, oleanolic acid, and nomilin, the diterpene andrographolide, and the monoterpenoids like limonene and perillic acid had shown immunomodulatory and antitumor activities. All of them could induce apoptosis in various cancer cells by activating various proapoptotic signaling cascades. Many of these terpenoids found to inhibit metastatic progression and tumor-induced angiogenesis. The molecular mechanisms that involved in these activities include inhibition of various oncogenic and anti-apoptotic signaling pathways and suppression or nuclear translocation of various transcription factors including nuclear factor kappa B (NF-κB). CONCLUSION: The chemopreventive and chemoprotective effects of these compounds point toward their possible role in modern anticancer therapies.