title: Mechanistic and kinetic study on the reactions of coumaric acids with reactive oxygen species: a DFT approach.
abstract: The mechanism and kinetics of reactions between coumaric acids and a series of reactive oxygen species ((•)OX) was studied through the density functional theory (DFT). H atom abstraction from -OH and -COOH groups and addition to the nonaromatic double bond were the most representative reaction pathways chosen for which free energy barriers and rate constants were calculated within the transition state theory (TST) framework. From these calculations, it was estimated that (•)OH > (•)OCH3 > (•)OOH > (•)OOCH3 is the order of reactivity of (•)OX with any coumaric acid. The highest rate constant was estimated for p-coumaric acid + (•)OH reaction, whereas the rest of the (•)OX species are more reactive with o-coumaric acid. On the basis of the calculated rate constants, H abstraction from a -OH group should be the main mechanism for the reactions involving (•)OCH3, (•)OOH, and (•)OOCH3 radicals. Nevertheless, the addition mechanism, which sometimes is not considered in theoretical studies on reactions of phenolic compounds with electrophilic species, could play a relevant role in the global mechanism of coumaric acid + (•)OH reactions.
authors.affiliation: Departamento de Quı́mica Física and ‡Departamento de Fı́sica Aplicada, Facultad de Farmacia, Universidad de Castilla-La Mancha , Paseo de los estudiantes s/n, 02071 Albacete, Spain.
authors.forename: Andrés
authors.initials: A
authors.lastname: Garzón
authors.forename: Iván
authors.initials: I
authors.lastname: Bravo
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Barbero
authors.forename: José
authors.initials: J
authors.lastname: Albaladejo
mesh_terms: D003373:Coumaric Acids / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry; D007700:Kinetics; D008956:Models, Chemical; D011422:Propionates; D017382:Reactive Oxygen Species / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D003373:Coumaric Acids; D011422:Propionates; D017382:Reactive Oxygen Species; D017665:Hydroxyl Radical; C495469:p-coumaric acid
keywords: DFT; coumaric acids; reactive oxygen species