Deprotonation of flavonoids severely alters the thermodynamics of the hydrogen atom transfer

The Substitution Effect on Reaction Enthalpies of Antioxidant Mechanisms of Juglone and Its Derivatives in Gas and Solution Phase: DFT Study

“…For J molecule in gas phase, the O 1 -H 1 BDE difference between the value calculated from monodeprotonated form (anion) and that obtained from neutral form equal to 49 kJ/mol demonstrates the fact that the deprotonation of the parent molecule severely alters the BDE values. This fact is in accordance with the previous investigation of the impact of the deprotonation of sixteen flavonoids on the OH BDE values carried by Klein et al [35]. The substitution of OH group by the OMe (J ) leads to a 17 kJ/mol increase in the O 1 -H 1 BDE.…”

Structural and electronic determinants of flavonoid binding to human serum albumin: an extensive ligand-based study

“…Flavonoid structures were recently explored using this method. 48,49 Analytical vibrational analysis was performed at the corresponding levels to characterize each stationary point on the potential energy surface as a minimum (NImag ¼ 0).…”

Theoretical Study of Primary Antioxidant Action Thermodynamics

“…Therefore, we have decided to calculate proton affinities, PA(A), of mono-deprotonated flavonoids. This study is under progress, but the first results indicate that PA(A) values are lower than BDE(A) values in aqueous solution (Klein et al 2017) a Data taken from (Klein et al 2016). …”

“…1. This structural change affects the antioxidant action, because isoflavones lack 3-OH group, which plays important role in free radical scavenging (Trouillas et al 2006, Klein et al 2016.…”

“…Because deprotonated polyphenolic compounds show different free radical scavenging action than parent molecules, our recent work (Klein et al 2016) is focused on the hydrogen atom transfer from the mono-deprotonated forms (phenoxide anions) of 8 flavonoids and 8 isoflavones in terms of O-H bond dissociation enthalpies. For deprotonated species, these are denoted as BDE(A) according Lemanska et al (2001).…”