title: Influence of different free radicals on scavenging potency of gallic acid.
abstract: The M05-2X/6-311++G(d,p) and B3LYP-D2/6-311++G(d,p) models are used to evaluate scavenging potency of gallic acid. The hydrogen atom transfer (HAT), sequential proton loss electron transfer (SPLET), and single electron transfer followed by proton transfer (SET-PT) mechanisms of gallic acid with some radicals ((•)OO(-), (•)OH, and CH3OO(•)) were investigated using the corresponding thermodynamic quantities: bond dissociation enthalpy (BDE), ionization potential (IP), and proton affinity (PA). Namely, the ΔHBDE, ΔHIP, and ΔHPA values of the corresponding reactions in some solvents (water, DMSO, pentylethanoate, and benzene) are investigated using an implicit solvation model (SMD). An approach based on the reactions enthalpies related to the examined mechanisms is applied. This approach shows that a thermodynamically favored mechanism depends on the polarity of reaction media and properties of free radical reactive species. The most acidic 4-OH group of gallic acid is the active site for radical inactivation. The results of this investigation indicate that the SPLET mechanism can be a favored reaction pathway for all three radicals in all solvents, except for (•)OH in the aqueous solution. In water, gallic acid can inactivate (•)OH by the HAT mechanism.
authors: Bioengineering Research and Development Center, 34000, Kragujevac, Republic of Serbia, jelena.djorovic@kg.ac.rs.
authors: Jelena
authors: J
authors: Đorović
authors: Jasmina M Dimitrić
authors: JM
authors: Marković
authors: Višnja
authors: V
authors: Stepanić
authors: Nebojša
authors: N
authors: Begović
authors: Dragan
authors: D
authors: Amić
authors: Zoran
authors: Z
authors: Marković
mesh_terms: D003198:Computer Simulation; D004583:Electrons; D016166:Free Radical Scavengers / Q000737:chemistry* / Q000494:pharmacology; D005609:Free Radicals / Q000737:chemistry*; D005707:Gallic Acid / Q000737:chemistry* / Q000494:pharmacology; D006859:Hydrogen; D006860:Hydrogen Bonding; D008956:Models, Chemical; D015394:Molecular Structure; D011522:Protons; D012997:Solvents / Q000737:chemistry; D013329:Structure-Activity Relationship; D013816:Thermodynamics
chemical_list: D016166:Free Radical Scavengers; D005609:Free Radicals; D011522:Protons; D012997:Solvents; D005707:Gallic Acid; D006859:Hydrogen