Document Detail


Plicatin B conformational landscape and affinity to copper (I and II) metal cations. A DFT study.
MedLine Citation:
PMID:  19290324     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The conformational landscape of the prenylchalcone plicatin B and some of its tautomers has been investigated at the B3LYP/6-31G* level in analogy to prior studies of ours on two structurally related prenylated pterocarpans. Since the antioxidant activity of these natural compounds is supposed to be related to their copper chelation ability, several complexes with Cu(i) and Cu(ii) metal cations, Cu(+) and Cu(2+), have been taken into account with the metal ions described by effective core potentials in the LANL2DZ valence basis set. The preferred binding sites on low-energy conformers of E and Z plicatin B have been determined and their metal ion affinity (MIA) values have been compared. Both cations give stable complexes with plicatin B, but the stability order of the metallated species at the various coordination sites strongly depends on the cation nature. In particular, for the E configuration the most stable Cu(+)-plicatin B ground-state structure features the metal cation bridged between the hydroxy O lone pairs and the prenyl pi density, while in the most stable Cu(2+) complex the cation is coordinated with the inner lone pairs of the oxygens in the methyl ester moiety bearing an anti methyl group. For the Z configuration, in contrast, the most stable Cu(2+) complexes are found with the metal ions dentated between the Z ester side chain and the prenyl pi density, while Cu(+) in addition is close to the aromatic ring density as well. A comparison of the Cu(+) and Cu(2+) affinity values demonstrates however that the affinity to Cu(2+) is decidedly much higher (by a factor of 3-4, depending on the arrangement type) than that to Cu(+), even including the possible B3LYP overestimate of the Cu(2+) binding energy with respect to BHLYP. A tentative evaluation of MIA in aqueous solution using the polarizable continuum model of the solvent shows a remarkable decrease for Cu(ii).
Authors:
Giuliano Alagona; Caterina Ghio
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Publication Detail:
Type:  Journal Article     Date:  2008-12-16
Journal Detail:
Title:  Physical chemistry chemical physics : PCCP     Volume:  11     ISSN:  1463-9076     ISO Abbreviation:  Phys Chem Chem Phys     Publication Date:  2009 Feb 
Date Detail:
Created Date:  2009-03-17     Completed Date:  2009-04-16     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100888160     Medline TA:  Phys Chem Chem Phys     Country:  England    
Other Details:
Languages:  eng     Pagination:  776-90     Citation Subset:  IM    
Affiliation:
CNR-IPCF, Molecular Modelling Lab, Via Moruzzi 1, I-56124, Pisa, Italy. G.Alagona@ipcf.cnr.it
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MeSH Terms
Descriptor/Qualifier:
Acrylates / chemistry*
Antioxidants / chemistry*
Binding Sites
Cations
Copper / chemistry*
Molecular Conformation
Pterocarpans / chemistry
Thermodynamics
Chemical
Reg. No./Substance:
0/Acrylates; 0/Antioxidants; 0/Cations; 0/Pterocarpans; 72704-01-9/plicatin B; 7440-50-8/Copper

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