Evaluation of the Antiradical Properties of Phenolic Acids

Abstract

Antioxidant capacity (AOC) against peroxyl radical and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) radical cation was measured for a series of p-hydroxybenzoic (HB) and p-hydroxycinnamic (HC) acids at different pH. Quantum-chemical computation was performed using Gaussian 3.0 software package to calculate the geometry and energy parameters of the same compounds. Significant correlations were revealed between AOC and a number of calculated parameters. The most significant AOC descriptors for the studied compounds against peroxyl radical were found to be HOMO energy, rigidity (η) and Mulliken charge on the carbon atom in m-position to the phenolic hydroxyl. The most significant descriptor of the antioxidant properties against the ABTS radical cation at pH 7.40 is electron transfer enthalpy from the phenolate ion. The mechanism of AOC realization has been proposed for HB and HC acids against both radicals.

Hydroxycinnamyl Derived BODIPY as a Lipophilic Fluorescence Probe for Peroxyl Radicals

“…Scheme 2 presents a proposed mechanism of a two-step oxidation of one receptor segment of NB-2: H atom abstraction from the phenolic hydroxy group by a peroxyl radical and a subsequent recombination of the formed phenoxyl radical with another peroxyl. This proposed mechanism is in accordance with the standard mechanism of reaction of peroxyl radicals with derivatives of hydroxycinnamic acids, such as p-coumaric, caffeic, ferulic, and sinapic acids [39]. Since recombination of phenoxyl radical with ROO• is very fast (for para-substituted phenols kr In both kinds of experiments carried out in methanol, with peroxyl radicals generated by photolysis and thermolysis of AIBN, we observed a maximal 14-fold fluorescence enhancement.…”

Mangosteen peel extract exhibits cellular antioxidant activity by induction of catalase and heme oxygenase-1 mRNA expression

“…For instance, phenolic compounds donate electrons to H 2 O 2 molecules and convert them to water molecules for scavenging of H 2 O 2 (Bendary, Francis, Ali, Sarwat, & El Hady, ). Moreover, phenolic compounds found in ME interacted and bound to the peroxyl radical to form a stable product to get rid of lipid peroxide (Koroleva et al, ). Interestingly, ME displayed anti‐lipid peroxidation activity, which had effects similar to those of vitamin E (a potent antioxidant).…”

Changes in the content of free phenolic acids and antioxidative capacity of wholemeal bread in relation to cereal species and fermentation type

“…The determined differences may be a result of the distinct mechanisms of these assays. For ORAC, hydrogen atom transfer (HAT) mechanism occurs, while DPPH proceeds by single electron transfer (SET) [67]. It seems that the HAT mechanism predominates for flour, bread and bread digestion.…”