Abstract

A common hallmark of human cancers is the over expression of telomerase, a ribonucleoprotein complex that is responsible for maintaining the length and integrity of chromosome ends and often directly correlated with the uncontrolled growth of cancer cells. Telomerase activity is present in 85-90% of all cancers, but absent in normal cells, which makes telomerase a good marker for cancer diagnosis and prognosis. Also, telomerase inhibition can be used as a novel anticancer therapy with reduced probability of toxicity than present antimalignancy drugs. However, current treatments used for cancer such as radiation, anti-hormonal therapy, surgery and chemotherapy using synthetic drugs, have been reported to produce various side effects. Therefore, it is crucial to reveal the beneficial effects of natural compounds with lesser side effects on normal cells and potential anticancer activity. In recent years, several natural molecules have been discovered so far that arrest proliferation of cancer cells by inhibiting telomerase. In this book chapter, we highlighted the effect of natural compounds on cancer cell proliferation, telomerase activity and their mechanism of action.