The antiradical activity of some selected flavones and flavonols. Experimental and quantum mechanical study

Abstract

The aim of the study was to examine the antiradical and antioxidant activity of some flavones and flavonols with different models of hydroxylation and methoxylation. Antiradical activity was measured using ABTS and DPPH radicals and ferric ions (FRAP test). The reduction potential of the compounds was also investigated by determination of minimal hydrogen abstraction energy for each of the hydroxyl hydrogens of all compounds using quantum chemistry methods. Quercetin appeared to be a strong antioxidant when the FRAP test was performed and the strongest for ABTS and DPPH tests whereas genkwanin was the weakest antioxidant for three tests (FRAP, ABTS, and DPPH). Flavonols appeared to have much stronger antiradical activity than flavones. An exception was luteolin, which belongs to flavones but exhibited antiradical activity comparable to that of flavonols, probably due to the presence of a hydroxyl group in the B ring at the 3' position next to another hydroxyl group at position 4'. The study using UB3LYP/6-31G(d,p) model chemistry of density functional theory (DFT) showed the lowest hydrogen abstraction energy (HAE) for the hydroxyl group situated at 3' or 5' of myricetin. Based on the experimental results and computational studies, we conclude that the hydroxyl group situated at 4' in the B ring in flavonoids, and to a lesser at the 3' and 3 position in flavonols is the most important for antioxidant activity of flavonoids. We observe strong negative Spearman's rank order correlations between minimal HAE and antiradical activity of flavonoids in all three tests and double-tailed rejection P values are less than 0.001.

Evaluation of Free Radical Scavenging Ability and Antiradical Activities of Ximenia Caffra Fruit Extracts at Different Ripening Stages

“…This study also revealed that X. caffra had strong antiradical activities than most other plant materials reported in the literature. Several studies have reported the presence of higher antiradical activities in different tea species than other plant materials [34][35][36][37]. However the quantities reported are lower than those of X. caffra observed in this study.…”

Analysis of Polyphenolic Compounds in Extracts from Leaves of SomeMalus domesticaCultivars: Antiradical and Antimicrobial Analysis of These Extracts

“…Our research clearly showed that phloridzin antiradical activity is high (higher than rutin). Our earlier research [40] showed that the presence of a hydroxyl group situated at the 4′ position in the B ring is very important for antiradical activity of flavones and flavonols (see phloridzin in Figure 5). It seems that in addition to the structure of 2,4,6 trihydroxyacetophenone with a hydroxyl group bonded to aromatic ring A at position 2 in phloridzin [39], also the 4′ hydroxyl group present in the B ring may be important for antioxidant activity.…”

Computational evaluation of the reactivity and pharmaceutical potential of an organic amine: A DFT, molecular dynamics simulations and molecular docking approach

“…Deviation of angles from the normal value 120°is due to the presence of hyperconjugative interaction. The torsion angles N-C(13)-C(12)-O (15) and N-C(9)-C(8)-O(11) with value −1.8°and −3.6°indicate that the glycinato arms are almost planar. To increase the strain in the glycinato arms they can be coordinated.…”

“…Dunning's basis set (aug-cc-pVDZ) has also been chosen apart from the regular basis set and implemented in various DFT methods. Computational techniques within the frameworks of DFT calculations and MD simulations provide outstanding tools for complementing experimental findings and understanding the reactivity of various molecular structures [14][15][16][17]. Various scientific and industrial areas rely on the efficiency of computational molecular modeling techniques [18][19][20][21][22].…”