Anti-Cancer Agents from Natural Sources

Abstract

One-sixth of the total deaths worldwide are directly caused by cancer which estimated 9.8 million deaths only in 2018. Furthermore, cancer-related mortalities are projected to rise to over 13.1 million by 2030. Many cancers are drug-resistant and practically no treatment is available. Cancer has negative impacts on the world-economy as only in 2010 the total economic cost was estimated at approximately US$1.16 trillion although the extensive role of cancer research is opening new frontiers to solve this fatal problem. Although surgery, immunotherapy, radiotherapy etc. can be used in the treatment of various cancers, still chemotherapy, either individual or along with other therapeutic procedures, is used to treat cancer in majority cases. Consequently, there is a general demand to discover/develop new and selective anticancer agents to eliminate/remove both cancer incidence and cancer related mortalities. Alternatively, Mother Nature provides us a lucrative, apparently unlimited wear house of various natural compounds that exhibit excellent anticancer activities. The utilization of the nature-made compounds and/or their novel cores, to develop 84the final drug entity, is still an interesting and highly promising area of drug discovery research. Since, 1940s to the end of 2014, the US Federal Drug Administration (FDA) or its similar organizations have approved 175 small molecules for the treatment of various types of cancers. Out of these 175 small molecule anticancer drugs 131 (74.85%) are completely non-synthetic molecules. Interestingly, 85 anticancer drug molecules (48.57%) are either actually being natural compounds or semi-synthetic molecules. Many natural or semi-synthetic compounds are also being used to treat several other diseases, e.g., about 78% of drugs that are generally used to combat microbial infections, are either obtained from nature or chemically-modified natural compounds. This chapter describes the pertinent recent examples of anticancer nature-derived compounds with special emphasis to commercial drugs (both natural and semi-synthetic). Based on their source (terrestrial plants, marine organisms, microbes, and animals) and core structure nature-derived molecules have been classified in several categories. Discussion on pharmacokinetics of various recently reported anticancer molecules is an interesting section of this chapter. In addition, brief discussion on phytoceuticals as chemosensitizer and radiosensitizer has been covered in this chapter.