Cancer Chemoprevention by Natural Products: Current & Future Prospects

Abstract

of mutational events in human cancers have provided evidence for a direct action of environmental carcinogens in the development of certain cancers. This loss of genetic integrity may result due to several cu mulative factors including exposure to harmful UV-radiation, potent mutagens and carcinogens, like genotoxic polyaromatic hydrocarbons (PAH), in humans and in experimental animal models. Therefore, a new science of chemoprevention has appeared as an attractive alternative to control malignancy. Plants have been utilized since time immemorial for curing various diseases. Herbal medicine is still the mainstay of about 75-80% of the world population, mainly in the developing countries for primary health care due to better cultural acceptability, better efficacy, better compatibility with the human body and lesser side effects. Fortunately, many plant derived antioxidant nutrients and phytochemicals have the advantage of low toxicity, therapeutic potential and are protective when administered at pharmacological doses. Therefore, screening of natural products and phytochemicals presents a major avenue for the discovery of new chemopreventive drugs. A large number of such natural compounds have been identified as having some potential cancer chemo preventive value, inhibiting mutagenesis, hyper proliferation or induce apoptosis or differentia tion, which are critical characteristics of chemoprevention. Such natural agents have clear practical advantages with regard to availability, suitability for oral application, regulatory approval and mechanism of action. Substances such as phytochemicals present in food and their derivatives have been identified by a combination of constituents in clude vitamin derivatives, phenolics and flavanoids agents, organic sul fur compounds, isothiocynates, curcumins, fatty acids, saponins and tannins, terpenes, alkaloids and d-limonene.