Cancer Preventive and Therapeutic Compounds: Gift From Mother Nature

Cancer stands as the second most common cause of disease-related death in humans. Although numerous anticancer drugs are available, mostly they are expensive with serious side effects. Thus, the challenging task of finding an alternative cancer treatment measure has become more important than ever to both scientists and physicians. Since natural compounds are known for their various health benefits for centuries, several nutritional factors have brought considerable attention as modifiable risk factors in the prevention and treatment of cancer. Based on currently available research, the present chapter focuses on the chemo preventive and chemotherapeutic properties of different natural/dietary compounds such as fruits, vegetable, spices, nuts, legumes, cereals and grains highlighting their potential use against cancer treatment. The molecular mechanisms by which theses dietary compounds inhibit cancer development and induce cell death are also included to a certain extent.

Allium sativum L (garlic) has a lengthy history as being a food and spice having a unique taste and odor along with many medicinal properties. Garlic is considered to be a natural medicine against variety of human ailments, including various antibacterial, antiviral and antifungal infections, antithrombotic, anticancer and anti tumorogenic activities. All these activities are linked to the level of organosulfur compounds like allicin, flavonoids, and phenolic components in it. Freshly chopped garlic contains Allicin, which is one of the highly biologically dynamic component. Allicin has reported to have a number of bioactivities including antioxidant, antiinflammatory activities. Many cardiovascular activities of allicin also have been worked out. The present paper reviews one of the major active ingredients in garlic – allicin – for its medicinal importance.

Cancer is the second leading cause of deaths worldwide, while it finds the top spot in diseases which still are not 100% curable. In the past few decades, a great deal of progress has been made in discovering new chemical entities, which enables us to understand the cause of cancer at cellular and molecular levels. In this regard, one of the naturally occurring triterpenoid class of compounds known as boswellic acids (BAs), have shown great potential for the development of new anticancer drugs. The interest in these type of triterpenoids has augmented since molecules such as NVX-207 and CDDO-Me have reached clinical trials. The alcoholic extract of the gum has also undergone clinical trials for the treatment of endotoxin induced hepatitis. Recently, the use of boswellic acid as well as its semi synthetic derivatives to treat cancer had been considered as an emerging concept in oncology as these have garnered considerable attention as a chemo-preventive and therapeutic agent in cancer.

Cancer chemoprevention is a rapidly evolving scientific research area. Cancer chemoprevention is the application of natural or synthetic agents to reduce or delay the onset of cancer. Different approaches are currently being used for cancer prevention and one of these important approaches is the use of natural compounds. Several natural compounds are currently under the investigation for their efficacy in preventing cancer. These compounds include curcumin, tea polyphenols, resveratrol, genistein, luteolin, lycopene among others. Curcumin is probably the most studied natural molecule for its ability to prevent cancer. Many of these compounds are being investigated using in vitro as well as animal models. Clinical trials are also underway for many natural compounds to test their efficiency in cancer chemoprevention. Recent evidence suggests that these natural molecules have antioxidant, anti-inflammatory, immune-enhancing, cell cycle modifying and cell differentiating, apoptotic and suppression of proliferation and angiogenesis properties. These natural compounds target several molecular pathways. Some of these pathways include p53 family, activator protein 1, NF-κB, growth factors among others.

Despite continuing scientific and commercial interests in cancer research around drug discovery, both less developed and developed countries are still trapped in the grip of this deadly and dreadful disease. Naturally occurring compounds represent approximately 50% of the chemotherapeutic agents, which have so far been brought to the market for cancer treatment. Traditional preparations have been the major source of cancer treatment in Africa, with traditional healers making regular use of these plants for the treatment of cancer and other ailments, since the continent is endowed with a rich floral bio-diversity. Africa's medicinal plants are known to biosynthesize interesting chemical structures with promising biological activities Thus, natural products from the African continent hold a premise for drug discovery and it is expected that the next generation of drugs, including potential anti-cancer drugs or the scaffolds necessary for the synthesis of new anti-cancer drugs could be lodged in African plants. We present some promising natural products for the anticancer drug development from African flora.

Radiation has been implicated in causing deleterious effect including cancer. Radiation exposure cause mutations, damage to the hematopoietic, gastrointestinal or central nervous systems which are critical causing adverse health effects. Hence, there is an urgent need to prevent such effects. A majority of phytochemicals have potential chemopreventive efficacy with relative less toxicity. Specifically, the utilization of these natural plants as modifiers of the radiation reaction is accepting extensive considerable attention. In this current review, we summarize the antimutagenic and anticancer effects of some selected natural phytochemicals including Amaranthus, Bael, Angelica, Rhamnoides, Haloil, Ginseng, Moringa, Biophytum etc against radiation induced damage.

Marine resources have rich pharmaceutical values as they encompass a diverse taxonomy of biological species and possess a large-scale of bioactive compounds. The existence of extraordinary chemical diversity of marine resources is used to discover anticancer agent in its natural or derived synthetic form. Marine flora and fauna possess several valuable compounds with immunostimulatory and antioxidant properties, also gained their importance as nutraceuticals as well as in cancer chemoprevention. In this chapter, we have emphasized for overviewing the marine natural products; those having anticancer or cancer chemo-preventive properties, acting against different deregulated cellular and molecular pathways associated with cancer development or progression.

Cancer is a major public health problem and the second leading cause of premature deaths worldwide, accounting for an incident rate of 2.6 million cases per year, mainly in Europe and the United States. This book chapter describes the historical aspect of cancer, its treatment modalities and history of natural compounds being used as anti-cancer agents. Role of marine natural compounds and their derivatives in cancer prevention, like, alkaloids, amine derivatives, macrolides, peptides and polypeptides are described in this chapter. Both, role of natural compounds extracted from plants and microbial sources are discussed along with their molecular targets and interactions to kill the cancer cells. Most of the medicinal compounds derived naturally are synthesized semi-synthetically for commercial purposes. They are then formulated into proper dosage increasing their costs. But for many natural compounds clinical trials are still to be carried out to validate their use in cancer therapy.

Data obtained from Human Genome Project has helped in transition of human diseases from a segmented view to a conceptual continuum. In accordance with this approach, identification of new gene targets has reinvigorated the field of natural product research and predominantly scientists are working to obtain these drugs through the use of high-throughput screening technologies and combinatorial chemistry. It is noteworthy that natural product templates combined with chemistry to selectively produce analogues will have higher chances of success. In this chapter we have attempted to summarize most recent advancements in clinical trials of natural products in different cancers. Keeping in view that structural variants contribute to the genomic landscape, multi-region whole-genome sequencing of hundreds of tumors will be helpful for a better understanding intra and inter-population genetic variability. Moreover, rapidly evolving field of nutrigenomics will play its part by tailoring the food or nutrition to the individual genotype. As we have developed deeper knowledge related to how wide ranging natural products modify cellular mechanisms, we may find that the continuum from pharmaceuticals to nutraceuticals through food-based biologically active phytochemicals will bring the disciplines of nutrigenomics and pharmacogenomics closer together.