INTRODUCTION1.1. CancerCancer is a dreaded disease which results due touncontrolled growth and spread of abnormal cells. It is one of the leading causes of death aroundthe world, despite significant advancements in the therapeutic options. Severalmillions of cancer cases are being reported and many million deaths are alsobeing reported worldwide on an annual basis. Over the past three to fourdecades cancer incidences are steadily increasing and in majority of the casescancer was found to be are more common to an ageing population.
Globalizationof unhealthy lifestyles, particularly cigarette smoking, adoption of manyfeatures of the modern western diet with high fat and low fiber content,combined with a sedentary lifestyle are being the major contributors towardsincreased cancer incidences (Alison, 2001). Thereare more than 100 different types of cancer which originate in different partsof the body or organs, grouped as carcinoma, melanoma, leukemia, lymphomas,sarcoma and the cancer of the nervous system, based on their tissue of origin. Itis also reported that more than 90% of the cancers occur in epithelia (NCI,2010).1.2. Cancer TreatmentThe primary modalities of cancer treatment aresurgery, chemotherapy and radiotherapy. The greatest drawback of thesetherapies is that none of these alone, or their combinations, could efficientlycontrol the metastatic cancer which requires treatment to reach every part ofthe body to be successful in eliminating the disease. The maindrawback of chemotherapy is the rapid development of resistance to multiplechemotherapeutic drugs (NCI, 2010).
Becauseof poor survival rates and associated side effects in the conventional cancertherapies, new therapeutic strategies are required more than ever for effectivetreatment and control of cancer. The current focus is on novel drugs,biological molecules from natural sources like the plants and the microbes withspecific signalling molecules in cancer as their targets. 1.3. Complementaryand alternative therapyComplementary andalternative therapy includes ayurvedic, traditional and herbal remedies thatare not part of standard medical care, that evolved from plants,micro-organisms and other natural sources. Alternativetherapy, involving natural compounds is gaining lot of importance and researchfocus during these days due to the inefficacy of synthetic drugs. Nature is an attractive source of novel therapeuticcompounds, as tremendous chemical diversity exists in the millions of speciesof plants, animals and microorganisms. Many of the commercially availableanticancer drugs have originated as chemical synthetic drugs or naturalcompounds derived from plants and microorganisms (Ma and Wang, 2009; Chabnerand Roberts, 2005; DeVita and Chu, 2008).
Compounds isolated from naturalresources have played very significant role as cancer chemotherapeutic agents inconventional therapies (Kinghorn, 2008). For over 40 years, the search fornaturally occurring compounds has continued from marine organisms includingplants, animals and the microorganisms, apart from terrestrial microorganismsand plants which are being investigated for their anti-cancer activities. Forexample, bisindole (vinca) alkaloids, the camptothecins, the taxanes and theepipodophyllotoxins are the members of four classes of plant-derived compoundswidely used as antitumor agents, whereas anthracyclines (such as doxorubicin),bleomycin, dactinomycin (actinomycin), and mitomycin C were included in theclass of antitumor antibiotics from microbes (Kinghorn, 2008). Ever since the discovery ofpenicillin from the fungus Penicillium chrysogenumin 1943, there was a shift of research focus from plants to microorganisms. Microorganismssuch as bacteria, fungi, yeast and microalgae are sources of structurallydiverse bioactive secondary metabolites that can act as catalysts for theproduction of enzymes, proteins, vitamins, organic acids, antibiotics and foodingredients along with their utility as therapeutics. As natural sources ofdrugs, micro-organisms have great potential for the treatment and prevention ofdiseases like diabetes, obesity, cancer, anaemia,diarrhoea and others (Gupta et al.2014).
1.4. Microbial pigments Pigmentsproduced by microorganisms as reminiscence of their secondary metabolism,commonly referred as biopigments (Shirata et al., 2000), have somenatural functions like protection against ultraviolet radiation(Romero-Martinez et al., 2000),protection against oxidants, protection against extremes of heat and cold,protection against natural antimicrobial compounds (Duin et al., 2002), antimicrobial activities, acquisition of nutrientsand energy by photosynthesis (Chew et al.,2007).
Many of the microbial pigments have potential clinical applications includingantibiotic, immumnosuppresive activities and in treating diseases like the cancer(Soliev, 2011).Ascancer evades all kinds of therapies, there is still an ongoing search fornovel anticancer compounds from natural sources. In our pursuit of finding analternative therapeutic compound to treat cancer, and also as we found thatmany microbial pigments have promising anticancer properties, the current studyis focused to evaluate the cytotoxic properties of pigments isolated frombacterial sources.