DFT Study of Quercetin Activated Forms Involved in Antiradical, Antioxidant, and Prooxidant Biological Processes

Abstract

Quercetin, one of the most representative flavonoid compounds, is involved in antiradical, antioxidant, and prooxidant biological processes. Despite a constant increase of knowledge on both positive and negative activities of quercetin, it is unclear which activated form (quinone, semiquinone, or deprotonated) actually plays a role in each of these processes. Structural, electronic, and energetic characteristics of quercetin, as well as the influence of a copper ion on all of these parameters, are studied by means of quantum chemical electronic structure calculations. Introduction of thermodynamic cycles together with the role of coreactive compounds, such as reactive oxygen species, gives a glimpse of the most probable reaction schemes. Such a theoretical approach provides another hint to clarify which reaction is likely to occur within the broad range of quercetin biological activities.

In vitroantioxidant activity of silymarin

“…In a previous study, it was shown that L-carnitine chelated ferrous ions (Fe 2þ ) through the carbonyl and hydroxyl functional groups [3]. Recently, Fiorucci and co-workers demonstrated that quercetin chelated metal ions in the same way [57].…”

Quercetin/β-cyclodextrin inclusion complex embedded nanofibres: Slow release and high solubility

“…Subsequently, a single QU molecule is introduced into the cavity of b-CD at various positions with different orientations. The three possible orientations of QU are labelled by its rings (A, B, C) (Fiorucci, Golebiowski, Cabrol-Bass, & Antonczak, 2007) and are shown in Fig. 2a.…”

Inhibition of Soybean Lipoxygenases – Structural and Activity Models for the Lipoxygenase Isoenzymes Family

“…These free radicals polymerize to yield a mixture of complex metabolites. However, it seems that quercetin may act, in most of cases, after being metabolically activated (Metodiewa et al, 1999), and despite a constant increase of knowledge on both positive and negative biological effects of this natural product, it remains often unclear which activated form should play a role in a given process (Fiorucci et al, 2007). Indeed, semiquinone and quinone forms of quercetin, deriving from the abstraction of respectively one or two H•, are involved in many oxidative processes (Metodiewa et al, 1999;Gliszczynska-Swiglo et al, 2003;Hirakawa et al, 2002).…”

“…Indeed, semiquinone and quinone forms of quercetin, deriving from the abstraction of respectively one or two H•, are involved in many oxidative processes (Metodiewa et al, 1999;Gliszczynska-Swiglo et al, 2003;Hirakawa et al, 2002). For instance, quercetin reduces peroxyl radicals involved in lipid peroxidation, and through this reaction, a semiquinone species is produced, which then undergoes a disproportionation to generate a quinone form (Fiorucci et al, 2007). Three semiquinone forms for quercetin have been considered by Fiorucci et al (2008) in order to study the quercetin binding to lipoxygenase-3 by molecular modeling simulations.…”