caa a22 4500 605510881 CHVBK 20210128100648.0 cr unu---uuuuu 210128e20150601xx s 000 0 eng 10.1007/s00894-015-2669-2 doi (NATIONALLICENCE)springer-10.1007/s00894-015-2669-2 Elucidation of hydroxyl groups-antioxidant relationship in mono- and dihydroxyflavones based on O-H bond dissociation enthalpies [Elektronische Daten] [Witcha Treesuwan, Songwut Suramitr, Supa Hannongbua] Radical scavenging potential is the key to anti-oxidation of hydroxyflavones which generally found in fruits and vegetables. The objective of this work was to investigate the influence of hydroxyl group on the O-H bond dissociation enthalpies (BDE) from a series of mono- and dihydroxyflavones. Calculation at the B3LYP/6-31G(d,p) level reveals the important roles of an additional one hydroxyl group to boost the BDE of hydroxyflavones that were a stabilization of the generated radicals through attractive H-bond interactions, an ortho- and para-dihydroxyl effect, and a presence of the 3-OH in dihydroxyflavones. On the other hand, the meta-dihydroxyl effect and range-hydroxyl effect especially associated with the either 5-OH or 8-OH promoted greater BDE. Results did not only confirm that dihydroxyflavones had lower BDE than monohydroxyflavones but also suggest the selective potent hydroxyflavone molecules that are the 6′-hydroxyflavone (for monohydroxyflavone) and the 5′,6′-, 7,8- and 3′,4′-dihydroxyflavone which the corresponding radical preferable generated at C6′-O•, C8-O• and C4′-O•, respectively. Electron distribution was limited only over the two connected rings of hydroxyflavones while the expansion distribution into C-ring could be enhanced if the radical was formed especially for the 2′,3′- and 5′,6′dihydroxyflavone radicals. The delocalized bonds were strengthened after radical was generated. However the 5-O• in 5,6-dihydroxyflavone and the 3-O• in 3,6′-dihydroxyflavone increased the bond order at C4-O11 which might interrupt the conjugated delocalized bonds at the keto group. Graphical Abstract This work suggests that a preferable region of the catechol group in dihydroxyflavones was selective. The 5′,6′-, 7,8-, and 3′,4′-dihydroxyflavone, which had the corresponding radical at C6′-O•, C8-O• and C4′-O•, shows higher potential of H-atom donation than others. Springer-Verlag Berlin Heidelberg, 2015 Functional food nationallicence Antioxidant nationallicence Hydroxyflavone nationallicence DFT nationallicence Bond dissociation enthalpy nationallicence Treesuwan Witcha Institute of Food Research and Product Development, Kasetsart University, 10900, Bangkok, Thailand aut Suramitr Songwut Department of Chemistry, Faculty of Science, Kasetsart University, 10900, Bangkok, Thailand aut Hannongbua Supa Department of Chemistry, Faculty of Science, Kasetsart University, 10900, Bangkok, Thailand aut Journal of Molecular Modeling Springer Berlin Heidelberg 21/6(2015-06-01), 1-10 1610-2940 21:6<1 2015 21 894 https://doi.org/10.1007/s00894-015-2669-2 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/s00894-015-2669-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Treesuwan Witcha Institute of Food Research and Product Development, Kasetsart University, 10900, Bangkok, Thailand aut NATIONALLICENCE 700 1- Suramitr Songwut Department of Chemistry, Faculty of Science, Kasetsart University, 10900, Bangkok, Thailand aut NATIONALLICENCE 700 1- Hannongbua Supa Department of Chemistry, Faculty of Science, Kasetsart University, 10900, Bangkok, Thailand aut NATIONALLICENCE 773 0- Journal of Molecular Modeling Springer Berlin Heidelberg 21/6(2015-06-01), 1-10 1610-2940 21:6<1 2015 21 894