title: Radical scavenging ability of gallic acid toward OH and OOH radicals. Reaction mechanism and rate constants from the density functional theory.
abstract: Gallic acid is a ubiquitous compound, widely distributed in the vegetal kingdom and frequently found in the human diet. In the present work, its primary antioxidant activity has been investigated using the density functional theory (DFT), and the quantum mechanics-based test for overall free radical scavenging activity (QM-ORSA) protocol. It was found that gallic acid is a better antioxidant than the reference compound, Trolox, regardless of the polarity of the environment. In addition, gallic acid is predicted to be among the best peroxyl radical scavengers identified so far in nonpolar (lipid) media. This compound is capable of scavenging hydroxyl radicals at diffusion-limited rates, and hydroperoxyl radicals with rate constants in the order of 10(5) M(-1) s(-1). The deprotonation of gallic acid, in aqueous solution, is predicted to increase the protective action of this compound against oxidative stress. Gallic acid was also identified as a versatile scavenger, capable of rapidly deactivating a wide variety of reactive oxygen species (ROS) and reactive nitrogen species (RNS) via electron transfer at physiological pH.
authors.affiliation: Dipartimento di Chimica e Tecnologie Chimiche, University of Calabria , Arcavacata di Rende, Cosenza, 87036, Italy.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Marino
authors.forename: Annia
authors.initials: A
authors.lastname: Galano
authors.forename: Nino
authors.initials: N
authors.lastname: Russo
mesh_terms: D001554:Benzene / Q000737:chemistry; D002839:Chromans / Q000737:chemistry; D003198:Computer Simulation; D004058:Diffusion; D004583:Electrons; D016166:Free Radical Scavengers / Q000737:chemistry*; D005707:Gallic Acid / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry; D008956:Models, Chemical; D015394:Molecular Structure; D010545:Peroxides / Q000737:chemistry*; D011789:Quantum Theory; D026361:Reactive Nitrogen Species / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D002839:Chromans; D016166:Free Radical Scavengers; D008055:Lipids; D010545:Peroxides; D026361:Reactive Nitrogen Species; D012997:Solvents; D014867:Water; D017665:Hydroxyl Radical; D005707:Gallic Acid; D001554:Benzene; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid