New Mechanisms of Action of Natural Antioxidants in Health and Disease

Natural antioxidants have been proposed to have beneficial effects on health and on different disease states, such as neurodegenerative and cardiovascular diseases, diabetes and cancer. The use of natural plant antioxidant products to handle different diseases has very ancient roots; well before the development of modern medicine with synthetic drugs and antioxidants. A lot of the biological activities of natural antioxidants have been ascribed to their ability to scavenge reactive oxygen species (ROS) that counteract oxidative stress. In the last years, a multitude of studies have suggested that their classical hydrogen-donating antioxidant activity is unlikely to be the sole explanation for their effects. First of all, natural antioxidants are subjected to an extensive metabolism in vivo that modifies their redox potentials. Moreover, the concentration of natural antioxidants and their metabolites in vivo are lower than that usually utilized in vitro. Accumulating evidence suggests that the cellular effects of natural antioxidants may also be mediated by their interactions with specific proteins central to intracellular signaling cascades, their modulation of the expression and activity of key proteins, their influencing of epigenetic mechanisms or their modulation of the gut microbiota. This special issue, concerning new mechanisms in the action of natural antioxidants in health and disease, contains nine contributions, seven research articles and two reviews, and details recent advances on this topic.