Natural Plant Extracts as Potential Therapeutic Agents for the Treatment of Cancer

Cancer, the much dreaded name, is a multifactorial and genetically a difficult disease with less or so far no 100% cure available. Globally, it has become a major social concern and worsened the economical burden, with emergence of 1,658,370 new cancer cases and 589,430 cancer deaths in the United States only in 2015. In India, the scenario is no better with high cancer prevalence of around 2.5 million incidences, with over 800,000 new cases occurring each year. By 2015, WHO has predicted estimated deaths by cancer to be 700,000. The increase could be accounted to urbanization, industrialization, hectic and unhealthy lifestyle, increased life expectancy and population growth. The current treatment regimes are becoming inefficacious due to tumor heterogeneity and increased resistance to drugs. Bioactive compounds from natural resources have revolutionized the arena of drug chemistry and rapid researches in in vitro and in vivo studies are encouraging. These natural therapeutic agents have therefore, become important for the development of multi- treatment strategies to be deployed in cancer therapy. The review summarizes the various chemopreventive and bioactive compounds isolated from several herbs which have become milestone in various kinds of tumor treatments. Also emphasis is led on including latest research data obtained from animal cell culture, animal models and preclinical trials studies conducted by scientists around the world to derive potential anti-tumorigenic agents. Finally, the review examines mechanisms of action of these compounds which will add to our existing knowledge and effort to serve and enhance the current chemotherapeutic protocols.