Departamento de Química. Universidad Autónoma Metropolitana-Iztapalapa.
San Rafael Atlixco 186, Col. Vicentina. Iztapalapa. C. P. 09340. México D. F. México.
Video is available only for registered users.
Oxidative stress is frequently caused by an excess of free radicals and has been associated with a wide variety of health disorders. Therefore, finding strategies for scavenging free radicals, or preventing their formation, has become an active area of research. Different reaction mechanisms involved in the chemical protection exerted by antioxidants will be discussed, as well as their relative importance depending on several aspects. A computational strategy designed to be a reliable tool in the study of radical-molecule reactions in solution is presented. It is referred to as Quantum Mechanics-based Test for Overall Free Radical Scavenging Activity (QM-ORSA). This methodology is intended to provide a universal and quantitative way of evaluating the free radical scavenging activity of chemical compounds. i.e. its primary antioxidant activity. This proposal includes a separated quantification of the activity in polar (aqueous) and non-polar (lipid) media. It also includes two different scales for quantification: absolute (based on overall apparent rate coefficients) and relative (using Trolox as the reference antioxidant). Using QM-ORSA also allows identifying the main mechanisms of reaction involved in the free radical scavenging activity of antioxidants, and establishing the influence of pH on such an activity. Validation of the QM-ORSA protocol by comparison with experimental results, is also presented, which demonstrate that its uncertainties are no larger than those arising from experiments.