Chemoprevention of cancer by isothiocyanates and anthocyanins: Mechanisms of action and structure-activity relationship

Carcinogenesis is a multi-step, multi-path and multi-focal process, which involves a series of epigenetic and genetic alterations that begin with genomic instability and end with the development of cancer. This long and complex process presents opportunities for the development of interventions both in preventing cancer initiation and in treating the neoplasm during its premalignant stages. Failure and high systemic toxicity of conventional cancer therapies have accelerated the search for newer agents, which could prevent and/or slow-down cancer growth and have more human acceptability by being less or non-toxic. Now, it is recognized that diets rich in fruits and vegetables are associated with lower risk of cancer. Taking cue from these observations, there is a strong interest in isolating and characterizing the nutritive and non-nutritive components of fruits and vegetables as potential chemopreventive agents. Isothiocyanates and anthocyanins, present in widely consumed fruits and vegetables, are two such agents. In recent years, increasing body of evidence has underscored the cancer preventive efficacy of isothiocyanates and anthocyanins in both in vitro and in vivo animal models. In this review article, we will provide detailed insight into the chemopreventive efficacy of isothiocyanates and anthocyanins based on the evidence generated from various studies performed using cell culture or animal models of epithelial cancers. Moreover, we will discuss the potential clinical relevance of the observed chemopreventive effects of these agents.