caa a22 4500 605511799 CHVBK 20210128100652.0 cr unu---uuuuu 210128e20151201xx s 000 0 eng 10.1007/s00894-015-2848-1 doi (NATIONALLICENCE)springer-10.1007/s00894-015-2848-1 The antiradical activity of some selected flavones and flavonols. Experimental and quantum mechanical study [Elektronische Daten] [Zbigniew Sroka, Beata Żbikowska, Jerzy Hładyszowski] 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. Springer-Verlag Berlin Heidelberg, 2015 Antioxidants nationallicence Density functional theory nationallicence Flavones nationallicence Flavonols nationallicence Minimal hydrogen abstraction energy nationallicence Sroka Zbigniew Department of Pharmacognosy, Wrocław Medical University, ul. Borowska 211, 50-556, Wroclaw, Poland aut Żbikowska Beata Department of Pharmacognosy, Wrocław Medical University, ul. Borowska 211, 50-556, Wroclaw, Poland aut Hładyszowski Jerzy Department of Physical Chemistry, Wrocław Medical University, ul. Borowska 211, 50-556, Wroclaw, Poland aut Journal of Molecular Modeling Springer Berlin Heidelberg 21/12(2015-12-01), 1-11 1610-2940 21:12<1 2015 21 894 https://doi.org/10.1007/s00894-015-2848-1 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00894-015-2848-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Sroka Zbigniew Department of Pharmacognosy, Wrocław Medical University, ul. Borowska 211, 50-556, Wroclaw, Poland aut NATIONALLICENCE 700 1- Żbikowska Beata Department of Pharmacognosy, Wrocław Medical University, ul. Borowska 211, 50-556, Wroclaw, Poland aut NATIONALLICENCE 700 1- Hładyszowski Jerzy Department of Physical Chemistry, Wrocław Medical University, ul. Borowska 211, 50-556, Wroclaw, Poland aut NATIONALLICENCE 773 0- Journal of Molecular Modeling Springer Berlin Heidelberg 21/12(2015-12-01), 1-11 1610-2940 21:12<1 2015 21 894