Anthocyanins: Janus nutraceuticals displaying chemotherapeutic and neuroprotective properties

Abstract

Anthocyanins are natural polyphenolic compounds widely distributed as pigments in many fruits and vegetables. In addition to displaying antioxidant properties, these nutraceuticals exhibit anti-inflammatory, anti-proliferative, and pro-apoptotic activities suggesting their potential as novel chemotherapeutic agents. Through cell cycle down-regulation, and context-specific pro-oxidant activity, anthocyanins induce cytotoxicity in cancer cells in vitro and in vivo. Specifically, via regulation of the Bcl-2 protein family and induction of caspase-dependent or caspase-independent apoptotic pathways, anthocyanins inhibit the growth of cancers by inducing cell death. Moreover, by modulating the activities of specific kinases and proteases, including (but not limited to) cyclin-dependent kinases, mitogen-activated protein kinases, matrix metalloproteases, and urokinase-type plasminogen activators, anthocyanins induce apoptosis, inhibit motility, and suppress invasion of cancer cells. In marked contrast to their effects in cancer cells, we have found that anthocyanins display significant anti-apoptotic activity in neurons. Antioxidant properties of these nutraceuticals, particularly at the level of the mitochondria, appear to underlie their neuroprotective effects. The opposing effects of anthocyanins on cancer cells and neurons suggest that these nutraceuticals are promising candidates for development as either chemotherapeutic agents or novel neuroprotective compounds for the treatment of cancers or neurodegenerative diseases, respectively.