Also available as PDF (figures and tables appear in the PDF).
The fundament of toxicology is the risk-benefit analysis. This means that the positive as well as the negative health effects of all compounds, including antioxidants, have to be assessed and related to each other. Only in this way the rational for the use of a compound can be evaluated.
Keywords: toxicology; risk-benefit analysis; Toxicity; Antioxidants
TOXICOLOGY AND FORENSIC MEDICINE Open Journal http://dx.doi.org/10.17140/TFMOJ-1-e002 Toxicol Forensic Med Open J ISSN 2474-8978 Bashir M. Rezk1*, Wim J. F. van der Vijgh2, Aalt Bast2 and Guido R. M. M. Haenen2 1Department of Natural Sciences, Southern University at New Orleans, New Orleans, LA 70126, USA 2Department of Toxicology, Maastricht University, P. O. Box 616, MD Maastricht 6200, The Netherlands *Corresponding author Bashir M. Rezk, PhD Assistant Professor of Biology Department of Natural Sciences Southern University at New Orleans 6400 Press Drive New Orleans, LA 70126, USA Tel. 504-284-5405; +1(504)957-8806 E-mail: batteia@suno.edu Article History Received: November 16th, 2015 Accepted: November 17th, 2015 Published: November 18th, 2015 Citation Rezk BM, van der Vijgh WJF, Bast A, Haenen GRMM. Toxicity of the antioxidants. Toxicol Forensic Med Open J. 2015; 1(1): e3-e4.
doi: 10.17140/TFMOJ-1-e002 Copyright ©2015 Rezk BM. This is an open access article distributed under the Creative Commons Attribution 4.0 International License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Volume 1 : Issue 1 Article Ref. #: 1000TFMOJ1e002 Toxicity of Antioxidants Page e3 Editorial The fundament of toxicology is the risk-benefit analysis. This means that the positive as well as the negative health effects of all compounds, including antioxidants, have to be as- sessed and related to each other. Only in this way the rational for the use of a compound can be evaluated.
The beneficial effects of antioxidants are due to their ability to protect against free radical damage. In the diseases and other pathological conditions where free radicals are im- plicated, the biochemistry may greatly vary, i.e. the radicals involved, their flux, the site where they are generated and the target they attack can differ.1 Thus for each type of radical damage specific criteria need to be fulfilled by an antioxidant in order to be active. Free radicals of biological interest are often divided into oxygen centred and nitrogen centred radicals. Reac- tive Oxygen Species (ROS) is a collective term that includes both oxygen centred radicals and certain oxygen containing non-radicals that are oxidizing agents or easily converted into radi- cals. In the Reactive Nitrogen Species (RNS) the reactivity of the species is located on or near a nitrogen atom. The adjective “reactive” is not always appropriate; H2O2, O2•- and NO• quickly react only with very few molecules. OH• reacts instantaneously with almost everything. RO2•, RO•, HOCl, NO2•, ONOOH, and O3 have a reactivity that lies in between these extremes. Regarding safety, in the 16th century Paracelsus already stated that all compounds are toxic, provided the dose is high enough. There is no reason to assume that antioxidants should be an exception to this rule. On the contrary, the mega-dosages sometimes recommended make safety a very relevant issue for antioxidants. The biological origin of most antioxidants helps to increase the acceptance of antioxidant supplementation by the general public. The perception is that the biological origin guarantees that antioxidants are not harmful; biological and natural is incorrectly thought to be synonymous to safe.2 The adage on the use of antioxidant supplementation seems to be: The more, the bet- ter. Indeed, antioxidant supplements are taken frequently by a great part of the public at a rela- tively high dose despite our limited knowledge on their beneficial health effect and safety. From a toxicological point of view, the free radical processes as well as the profiles of antioxidants have to be elucidated to a greater extend to be able to further rationalize and optimize antioxi- dant therapy.3
An important issue in the use of antioxidants is metabolism.4 Like other bioactive compounds, metabolites formed by phase 1 and phase 2 enzymes can contribute to the benefi- cial and toxic effect of an antioxidant. More importantly, during the actual antioxidant activity of a free radical scavenging antioxidant, it is converted into a metabolite.1 The effect of such a metabolite on a biological system is relevant since the metabolite usually contains some re- sidual reactivity of the radical that has been scavenged.
According to 2013, Annual Report of the American Association of Poison Control Centers (AAPCC): National Poison Data System (NPDS), more than 65,000 instances of vita- min toxicity are reported annually to US poison control centers.5 Unintentional and intentional exposures continue to be a significant cause of morbidity and mortality in the United States.4 It TOXICOLOGY AND FORENSIC MEDICINE Open Journal http://dx.doi.org/10.17140/TFMOJ-1-e002 Toxicol Forensic Med Open J ISSN 2474-8978 Page e4 is of importance to identify groups that are at risk. In spite of the focus on the adverse effects of antioxidants and vitamins, priority should be given to identify groups that are likely to benefit.6 The bottom line is that in the appraisal of antioxidants, their benefits must first be identified and substantiated by elucidat- ing the molecular mechanism. The risks must then be identified the molecular mechanism. The optimal benefit-risk ratio has to be determined for each antioxidant and each individual separately, also taking into account, the dose.7 CONFLICTS OF INTEREST The authors declare that they have no conflicts of interests.