1. advancements in the therapeutic options. Several millions of

1.     INTRODUCTION

1.1.      
Cancer

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Cancer is a group of diseases characterized by
uncontrolled growth and spread of abnormal cells. It is one of the leading causes of death around
the world, despite significant advancements in the therapeutic options. Several
millions of cancer cases are being reported and many millions deaths are also
being reported worldwide on an annual basis. Over the past three to four
decades cancer incidences are steadily increasing and most cancers are more
prevalent in an ageing population. Globalization of unhealthy lifestyles,
particularly cigarette smoking, adoption of many features of the modern western
diet with high fat and low fiber content, combined with a sedentary lifestyle
are being the major contributors towards increased cancer incidences (Alison,
2001).

There
are more than 100 different types of cancer which originate in different parts
of the body or organs, grouped as carcinoma, melanoma, leukemia, lymphomas, sarcoma
and the cancer of the nervous system, based on their tissue of origin. It is
also reported that more than 90% of the cancers occur in epithelia (NCI, 2010).

1.2.      
 Cancer Treatment

The primary modalities of cancer treatment are
surgery, chemotherapy and radiotherapy. The greatest drawback of these
therapies is that none of these individually, nor their combinations, could
adequately control the metastatic cancer which requires treatment to reach
every organ of the body to be effective. The main
drawback of chemotherapy is the rapid development of resistance to multiple
chemotherapeutic drugs (NCI, 2010). Because
of poor survival rates and associated side effects in the conventional cancer
therapies, new therapeutic strategies are required more than ever for effective
treatment and control of cancer. The current focus is on novel drugs,
biological molecules from natural sources like the plants and the microbes with
specific signalling molecules in cancer as their targets.

1.3.      
 Complementary
and alternative therapy

Complementary and
alternative therapy includes ayurvedic, traditional and herbal remedies that
are not part of standard medical care, that evolved from plants,
micro-organisms and other natural sources. Alternative
therapy, involving natural compounds is gaining lot of importance and research
focus during these days due to the inefficacy of synthetic drugs. Nature is an attractive source of novel therapeutic
compounds, as tremendous chemical diversity exists in the millions of species
of plants, animals and microorganisms. Many of the commercially available
anticancer drugs have originated as chemical synthetic drugs or natural
compounds derived from plants and microorganisms (Ma and Wang, 2009;
Chabner and Roberts, 2005; DeVita and Chu, 2008). Natural compounds have played
very significant role as conventional cancer chemotherapeutic agents (Kinghorn,
2008). For over 40 years, the search for naturally occurring compounds has
continued from marine fauna and flora, terrestrial microorganisms and plants
which are being investigated for their anti-cancer activities. For example,
bisindole (vinca) alkaloids, the camptothecins, the taxanes and the
epipodophyllotoxins are the members of four classes of plant-derived compounds
widely used as antitumor agents, whereas anthracyclines (such as doxorubicin),
bleomycin, dactinomycin (actinomycin), and mitomycin C were included in the
class of antitumor antibiotics from microbes (Kinghorn, 2008).

Ever since the discovery of
penicillin from the fungus Penicillium chrysogenum
in 1943, there was a shift of research focus from plants to microorganisms. Microorganisms
such as bacteria, fungi, yeast and microalgae are sources of structurally
diverse bioactive secondary metabolites that can act as catalysts for the
production of enzymes, proteins, vitamins, organic acids, antibiotics and food
ingredients apart from being used in therapeutic applications. As natural
sources of drugs, micro-organisms have great potential for the treatment and
prevention of diseases like cancer, anaemia, diarrhoea, obesity,
diabetes and the like (Gupta et al.
2014).

1.4.      
 Microbial pigments

Pigments
produced by microorganisms as reminiscence of their secondary metabolism,
commonly referred as biopigments (Shirata et al., 2000), have some
natural 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 nutrients
and energy by photosynthesis (Chew et al.,
2007). Many of the microbial pigments have potential clinical applications including
antibiotic, immumnosuppresive activities and in treating diseases like the
cancer (Soliev, 2011).

As
cancer evades all kinds of therapies, there is still an ongoing search for
novel anticancer compounds from natural sources. In our pursuit of finding an
alternative therapeutic compound to treat cancer, and also as we found that
many microbial pigments have promising anticancer properties, the current study
is focused to evaluate the cytotoxic properties of pigments isolated from
bacterial sources.