Thermodynamics of primary antioxidant action of flavonols in polar solvents
Institute of Physical Chemistry and Chemical Physics, Slovak University of Technology in Bratislava,
Radlinského 9, SK-812 37 Bratislava, Slovakia
a Department of Chemistry, University of SS. Cyril and Methodius, J. Herdu 2, SK-917 01 Trnava, Slovak Republic.
E-mail: * email@example.com
Abstract: Very recently, a report on the antioxidant activity of flavonoids has appeared, where authors concluded that Hydrogen Atom Transfer mechanism represents the thermodynamically preferred mechanism in polar media (https://doi.org/10.1016/j.foodres.2018.11.018). Unfortunately, serious errors in the theoretical part of the paper led to incorrect conclusions. For six flavonols (galangin, kaempferol, quercetin, morin, myricetin, and fisetin), reaction enthalpies related to three mechanisms of the primary antioxidant action were computed. Based on the obtained results, the role of intramolecular hydrogen bonds (IHB) in the thermodynamics of the antioxidant effect is presented. Calculations and the role of solvation enthalpies of proton and electron in the determination of thermodynamically preferred mechanism is also briefly explained and discussed. The obtained results are in accordance with published works considering the Sequential Proton-Loss Electron-Transfer thermodynamically preferred reaction pathway.
Keywords: phenolic antioxidant; intramolecular hydrogen bond; DFT calculation; sequential proton-loss electron-transfer; solvent effect
Full paper in Portable Document Format: acs_0333.pdf
Acta Chimica Slovaca, Vol. 12, No. 1, 2019, pp. 108—118, DOI: 10.2478/acs-2019-0016