Antioxidants: Positive or Negative Actors?

Abstract

The term “antioxidant” is one of the most confusing definitions in biological/medical sciences. In chemistry, “antioxidant” is simply conceived “a compound that removes reactive species, mainly those oxygen-derived”, while in a cell context, the conceptual definition of an antioxidant is poorly understood. Indeed, non-clinically recommended antioxidants are often consumed in large amounts by the global population, based on the belief that cancer, inflammation and degenerative diseases are triggered by high oxygen levels (or reactive oxygen species) and that through blocking reactive species production, organic unbalances/disorders can be prevented and/or even treated. The popularity of these chemicals arises in part from the widespread public mistrust of allopathic medicine. In fact, reactive oxygen species play a dual role in dealing with different disorders, since they may contribute to disease onset and/or progression but may also play a key role in disease prevention. Further, the ability of the most commonly used supplements, such as vitamins C, E, selenium, and herbal supplements to decrease pathologic reactive oxygen species is not clearly established. Hence, the present review aims to provide a nuanced understanding of where current knowledge is and where it should go.

Impact of Natural Compounds on Neurodegenerative Disorders: From Preclinical to Pharmacotherapeutics

“…Antioxidant activity has been previously reported in a wide range of phytochemicals, with apigenin, baicalein, berberine, crocin, curcumin, ginsenosides, quercetin, resveratrol and rutin being some of the most effective [15,[65][66][67]. Baicalein attenuated 6-hydroxydopamine (6-OHDA)-induced neurotoxicity (a common model of PD) by minimizing mitochondrial dysfunction and OS, and prevented NO production, by inhibiting inducible nitric oxide synthase (iNOS) in microglia [45].…”

Plant-Derived Bioactives and Oxidative Stress-Related Disorders: A Key Trend towards Healthy Aging and Longevity Promotion

“…Under steady-state conditions, ROS molecules are scavenged by various antioxidant defense mechanisms [5]. In this sense, the antioxidant potential of plants has attracted a great deal of attention, because increased oxidative stress has been reported as a major contributing factor to both the development and progression of aging and numerous life-threatening disorders, including neurodegenerative and cardiovascular diseases [6,7].…”

Phenolic compounds and multivariate analysis of antiradical properties of red fruits

“…Antioxidants are compounds which reduce and block free radicals [6,7]. They form metal complexes that catalyze oxidation reactions, prevent reactions caused by single active oxygen, and inhibit the activity of oxidative enzymes, such as lipoxygenase.…”