Density functional computations of the energetic and spectroscopic parameters of quercetin and its radicals in the gas phase and in solvent

Università della Calabria, Rende, Calabria, Italy
Theoretical Chemistry Accounts (Impact Factor: 2.23). 02/2004; 111(2):210-216. DOI: 10.1007/s00214-003-0544-1


Quercetin and its radicals were investigated at the B3LYP density functional level with the aim of determining the energetic and spectroscopic parameters and the factors that influence their antioxidant activity in the gas phase and in aqueous solution. The results indicated that the antioxidant ability of quercetin is mainly due to the orthodiphenolic moiety but also to the presence of the C=C double bond of the pyrone ring. Differences in the stability order of the isomers of quercetins radicals were found in going from vacuum to solvent. Hyperfine coupling constants were computed to help the interpretation of the intricate ESR spectrum of quercetin.

Download full-text


Available from: Nino Russo,
1 Follower
75 Reads
  • Source
    • "with water molecules compensate for the lack of IHBs. As already emphasized (Leopoldini et al., 2004a, 2004b; Trouillas et al., 2006; Markovi´c & Manojlovi´c, 2010), spin density can be used to determine the potential for delocalization and, thus, the stability of polyphenol radicals. The spin distribution obtained by the NBO analysis of the O5R3 and O4R1 radicals in both media revealed that the unpaired electron is delocalized over O5 (O4) and it corresponds to ortho and para carbon atoms. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Antioxidant activity of erodiol was examined at the M05-2X/6-311+G(d,p) level of theory in the gas and aqueous phases. The structure and energy of radicals and anions of the most stable erodiol rotamer were analyzed. To estimate antioxidant potential of erodiol, different molecular properties were examined: bond dissociation enthalpy, proton affinity together with electron transfer energy, and ionization potential followed by proton dissociation enthalpy. It was found that hydrogen atom transfer is the prevailing mechanism of erodiol behavior in gas; whereas single electron transfer followed by proton transfer and sequential proton loss electron transfer mechanisms represent the thermodynamically preferred reaction paths in water.
    Chemical Papers- Slovak Academy of Sciences 11/2013; 67(11). DOI:10.2478/s11696-013-0402-0 · 1.47 Impact Factor
  • Source
    • "Molecules differ in the ortho-diphenolic moiety in the ring B, so that in the case of luteolin the H-atom abstraction is easier because the derived radical can be stabilized by the intramolecular hydrogen bond. The BDE of flavonols kaempferol and quercetin is evaluated to be 80.9 (Leopoldini et al., 2004a) and 72.3 (Leopoldini et al., 2004b) kcal/mol at B3LYP/6-311++G** level (Table 2). Because the only difference between them is the 3 0 -OH group in the ring B, the presence of this group lowers the energy required for the H abstraction by 8.6 kcal/mol. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In this review, we present a summary of the research work performed so far using high accuracy quantum chemical methods on polyphenolic antioxidant compounds. We have reviewed the different groups of polyphenols, which mostly belong to the Mediterranean food culture, i.e. phenolic acids, flavonoids and stilbenes. The three main proposed mechanisms through which the antioxidants may play their protective role, which is the H atom transfer, the single electron transfer and the metals chelation, have been analysed and discussed in details. This work represents a further important contribution to the elucidation of the beneficial effects on health of these substances.
    Food Chemistry 03/2011; 125(2):288–306. DOI:10.1016/j.foodchem.2010.08.012 · 3.39 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The structural and antioxidant activity properties of three flavonols kaempferol, galangin and morin have been investigated at density functional level of theory with the aim of verifying experimental findings. The potentialities of antioxidant activity are highly related to their capabilities to scavenge free radicals. Two potential working mechanisms of the hydrogen-atom transfer and single-electron transfer are reported by which antioxidants can play their role. Two parameters of the O-H bond dissociation enthalpy (BDE) and ionization potential (IP) in the presence of water medium are computed to estimate the antioxidant capacities. Results indicate that the order of antioxidant efficacies predicted theoretically in this work is in agreement with that reported by experimental results of oxygen radical-scavenging capacity (ORAC) assay. This demonstrates the importance of the hydrogen-atom and single-electron transfer mechanisms to explain their capacities to scavenge peroxyl radical.
    Food Biophysics 06/2012; 8(2). DOI:10.1007/s11483-012-9276-x · 1.63 Impact Factor
Show more