Molecular transduction mechanisms of the redox network underlying the antiproliferative effects of allyl compounds from garlic

Much evidence in the last few years suggests that the antiproliferative effects of various garlic secondary metabolites in in vitro experimental systems are due to redox-based mechanisms. In particular, sulfur-containing allyl compounds have been demonstrated to generate reactive oxygen species and to modify directly the redox state of specific reactive cysteines on protein surfaces. On the basis of such properties, allyl compounds, in particular the ones present in the oil-soluble fraction of garlic extracts, can function as modulators of several redox-mediated signaling pathways related to the activation of mitogen-activated protein kinases, cell cycle, DNA repair, and cell demise. However, even though many in vitro studies have tried to dissect the mechanisms of action of garlic derivatives, research in this field is still incomplete and questions about bioavailability, biotransformation, and pro-oxidant activity are still unanswered. This review discusses recent findings on such aspects, focusing on the chemistry of allyl compounds and their preferential cellular targets as well as on related nutritional aspects.