Document Detail

Antioxidant activity of phenolic and related compounds: a density functional theory study on the O-H bond dissociation enthalpy.
MedLine Citation:
PMID:  15606979     Owner:  NLM     Status:  MEDLINE    
We report here on calculations at the hybrid DFT/HF (B3-LYP/6-31G(d, p)) level of the O-H bond dissociation enthalpy (O-H BDE) of phenylpropenoic acids (caffeic, ferulic, p-coumaric and cinnamic) and phenolic acids and related compounds (gallic, methylgallate, vanillic and gentisic) in order to gain insight into the understanding of structure-antioxidant activity relationships. The results were correlated and discussed mainly on the basis of experimental data in a companion work (Galato D, Giacomelli C, Ckless K, Susin MF, Vale RMR, Spinelli A. Antioxidant capacity of phenolic and related compounds: correlation among electrochemical, visible spectroscopy methods and structure-antioxidant activity. Redox Report 2001; 6: 243-250). The O-H BDE values showed remarkable dependence on the hydroxyl position in the benzene ring and the existence of additional interaction due to hydrogen bonding. For parent molecules, the experimental antioxidant activity (AA) order was properly obeyed only when intramolecular hydrogen bonding was present in the radicalized structures of o-dihydroxyl moieties. In structurally related compounds, excellent correlation with experimental data was in general observed (0.64 < rho < 0.99). However, it is shown that excellent correlation can also be obtained for this series of compounds considering p-radicalized structures which were not stabilized by intramolecular hydrogen bonding, but this had no physical meaning. These findings suggested that the antioxidant activity evaluation of phenolic and related compounds must take into consideration the characteristics of each particular compound.
Cristiano Giacomelli; Fabio da Silva Miranda; Norberto Sanches Gonçalves; Almir Spinelli
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Redox report : communications in free radical research     Volume:  9     ISSN:  1351-0002     ISO Abbreviation:  Redox Rep.     Publication Date:  2004  
Date Detail:
Created Date:  2004-12-20     Completed Date:  2005-05-12     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9511366     Medline TA:  Redox Rep     Country:  England    
Other Details:
Languages:  eng     Pagination:  263-9     Citation Subset:  IM    
Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
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MeSH Terms
Antioxidants / chemistry*,  pharmacology
Caffeic Acids / chemistry
Chromans / pharmacology
Cinnamates / chemistry
Coumaric Acids / chemistry
Gallic Acid / analogs & derivatives*,  chemistry
Gentisates / chemistry
Hydrogen Bonding
Hydroxybenzoic Acids / chemistry*,  pharmacology*
Models, Chemical
Oxygen / chemistry
Structure-Activity Relationship
Vanillic Acid / chemistry
Reg. No./Substance:
0/Antioxidants; 0/Caffeic Acids; 0/Chromans; 0/Cinnamates; 0/Coumaric Acids; 0/Gentisates; 0/Hydroxybenzoic Acids; 108-95-2/Phenol; 121-34-6/Vanillic Acid; 149-91-7/Gallic Acid; 29656-58-4/phenolic acid; 331-39-5/caffeic acid; 3934-84-7/3-O-methylgallic acid; 490-79-9/2,5-dihydroxybenzoic acid; 56305-04-5/6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; 621-82-9/cinnamic acid; 7400-08-0/4-coumaric acid; 7782-44-7/Oxygen

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