PLANTS AND ITS PARTS AS A SOURCE OF ANTI- CANCER COMPOUNDS: A REVIEW

Abstract

Plant has been used in the treatment of many diseases and now it has shown tremendous potential in the treatment of cancer. Various parts of plant including whole plant, leaves, bark, roots and fruits yield compounds which show greater prospective of treating cancer cells in the biological system. This review gives an insight about the anti-cancer compounds isolated from plants and its parts. The compounds described consist of marketed drugs, drugs under clinical trials, and herbs which have been not tested on human models. This review also illustrates that which drug is effective against the type of cancer. The review concludes with the future prospects of these compounds which could be marketed for the better health of the patients. INTRODUCTION Cell is a basic structural unit of every living organism whether unicellular or multicellular. It is independent machinery which already has set of instructions incorporated in it and it initiates those set of instruction according to its requirement. Those set of instruction includes a cascade of reactions which performs various function like energy production through mitochondria or chloroplast, producing hormones or enzyme, giving mechanical support or to form a whole organism. It consist instructions for its own growth and development. But what if this machinery goes wrong? What if a cell starts performing haphazard functions? What if it starts initiating wrong set of instructions? These answer to these question would be, that it would create a huge havoc in the body. The consequence of this situation would be production of damaged cells that would result in death of individual cells or uncontrolled cell proliferation resulting in the formation of tumor leading to cancer. Cell cycle is defined as a process by which a cell divides and multiplies in number. The process is responsible for the development of various organisms. As described earlier, the cell consists of instructions for cell division which are controlled by various molecules like enzymes, protein molecules and the whole cell cycle machinery. The cycle consists of 3 broad phases-(i) Interphase, during which cell grows and enlarges itself by accumulating all the materials needed for next phase-(ii) Mitotic phase. It includes S phase, the synthetic phase which involves duplication of DNA. After this phase the cell divides into 2 daughter cells. The mitotic phase includes the third phase (iii) cytokinesis where the cytoplasm divides into two daughter cells to form mature new cells. During this division there are various checkpoints which regulate the division at a proper rate and carry out the division in a systematic way. Cancer which is the result of uncontrolled proliferation of cell occurs due to disturbance in the division process like the checkpoint machinery fails to identify the flaw during division. The cancer cells do not undergo apoptosis and start infecting healthy cells by metastasis. This disrupts the complete cell cycle machinery causing collapse of the system. Cancer is a catastrophic event in human body, disturbing the physiological, physical, social and mental well-being¹. It is a pandemic disease inflicting the human beings since 1600 B.C. and has been a puzzle till date. Though we have put some pieces of the puzzle together but till now we are not able to create the clear picture. This unclear picture has given rise to present day therapies like radio therapy which has a recovery rate of 33 %, insisting the need of an adjuvant therapy called as chemotherapy¹. Though we have treatment procedure for the disease but the global death toll has increased. According to the press release (December 2013) by International Agency for Research on Cancer (WHO), the global cancer burden has increased to 14.1 million new cases in 2012 and 8.2 million cancer deaths in 2012. There has been a marked increase in breast cancer and cervical cancer globally. The most commonly diagnosed cancer was lung cancer (1.8 million, 13 % of the total), breast cancer (1.7 million, 11.9 %) and colorectum cancer (1.4 million, 9.7 %). The widespread cause of cancer death were lung cancer (1.6 million, 19.4 % of total), liver cancer (0.8 million, 9.1 %) and stomach cancer (0.7 million, 8.8 %). It has been estimated that there would be significantly increase to 19.3 million new cancer cases per year by 2025 2-4 . Looking at the above statistics we understand that there is a dire need of introducing efficient treatments and potential drugs. A large group of compounds have been tested for their anti-cancer activity on the tumor systems