Free radical scavenging capacity of hydroxycinnamic acids and related compounds

Abstract

The capacity of hydroxycinnamic acid derivatives to trap peroxyl radicals was evaluated by competitive kinetics and oxygen radical absorbance capacity (ORAC) indexes, using c-phycocyanin and pyranine as target molecules. The pattern of results is similar in all the systems, with the reactivity of the compound determined by the bond dissociation energy (BDE) of the hydrogen atom of the phenolic moiety. However, differences in the relative reactivity are observed depending upon the employed methodology (initial rate of consumption or ORAC-type methodology) and target molecule employed. These differences are explained in terms of the role played by secondary reactions of the initially formed phenoxyl radicals. This emphasizes the need for performing a complete kinetic analysis of the results in order to obtain meaningful evaluations of the relative reactivity of the tested compounds.

Stability of encapsulated olive oil in the presence of caffeic acid

“…Caffeic acid (CA), a potent antioxidant among the hydroxycinnamic acids, is widespread in the plant kingdom (Gülçin, 2006;Murkovic, 2003;Rice-Evans, Miller, & Paganga, 1996). The use of CA may provide dual benefits through inhibiting lipid oxidation since it is a free radical scavenger, while also increasing the nutritional values of the final product (Gülçin, 2006;Marinova & Yanishlieva, 1992, 1994Pino, Campos, Lopez-Alarcon, Aspee, & Lissi, 2006).…”

Reactivity of phenolic compounds towards free radicals under in vitro conditions

“…But they employed the oxygen radical absorbance capacity (ORAC) and lipid peroxide inhibition capacity (LPIC) assays. Pino et al (2006) evaluated the capacity of hydoxycinnamic acids to trap peroxyl radicals by using oxygen radical absorbance capacity (ORAC) indexes. Haseloff et al (1990) studied the in vitro hydroxyl radical scavenging activity of benzoic acid esters and propyl gallate.…”

Relevance of Secondary Processes in Orac Values Obtained Employing Pyrogallol Red as Target Molecule

“…This could be directly related to the strength of the POH bond and/or to the electron affinity of the radical. 8 This would explain why process (6) is less relevant for sinapic acid. The rate constant of process ii) (2) (PO + PO processes).…”