Plant phenolics in cancer chemoprevention

Phenolics are generally widely distributed in the plant kingdom and are the most plentiful secondary metabolites of plants. Plant polyphenols have pinched increasing attention due to their effective antioxidant properties and their marked effects in the prevention of a variety of oxidative stress related diseases such as cancer. The antioxidant content of fruits and vegetables may contribute to the protection they put forward from disease. Because plant foods include many different classes and types of antioxidants, information of their total antioxidant capacity (TAC), which is the cumulative capacity of food components to hunt free radicals, would be valuable for epidemiologic purposes. Evidence reviewed here demonstrates exogenous antioxidants alone produce beneficial effects in various cancers. Among fruits, the highest antioxidant activities found in berries (i.e., blackberry, red currant and raspberry) has shown a significant effect on the deterrence of cancer development. This review provides a rationalized and ample overview on phenolic antioxidants from natural sources with their in-vitro and in-vivo anticancer activity. The anticancer effects of phenolics in-vitro and in-vivo animal models are viewed, together with recent human intervention studies.