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Updated: Jun 28, 2026

Biosynthesis of a Flavonol from a Flavanone by Establishing a One-pot Bienzymatic Cascade
Published on: August 14, 2019
Bond dissociation enthalpies calculated by the PM3 method confirm activity cliffs in radical scavenging of flavonoids
Dragan Amić1, Bono Lucić, Goran Kovacević
1Faculty of Agriculture, The Josip Juraj Strossmayer University, P.O. Box 719, 31107, Osijek, Croatia. damic@pfos.hr
Abstract:
Radical scavenging potency of flavonoids is associated with activity cliffs, i.e., small chemical modifications on flavonoid core can have a significant effect on activity. The presence or absence of the 3',4'-diOH and/or 3-OH group may serve as an activity switch for radical scavenging. The physicochemical background of such an indicator variable, defined previously (Amić et al. (2003) Croat Chem Acta 76:55-61), is confirmed by computation of bond dissociation enthalpies and selecting the minimal of all values relating to flavonoid OH groups. Bond dissociation enthalpies for hydrogen abstraction from OH groups for 29 flavonoids were calculated by the PM3 method. Minimal bond dissociation enthalpy values were obtained for OH groups attached to C-3, C-3' and C-4' positions, and they correspond to the previously introduced indicator variable. Taking into account some driving forces of the radical scavenging mechanism, it is possible to relate structural characteristics of flavonoids to their radical scavenging potency as well as to develop reliable structure-activity models.
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