Medium effects on the antioxidant activity of dipyridamole

Very strong medium effects have been observed when testing the antioxidant activity of dipyridamole (DP) in different media such as benzene, tert-butanol, methanol solutions and egg yolk lecithin unilamellar and multilamellar vesicles. Actually, dipyridamole behaves as a very poor antioxidant in ben...

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Published in:Free radical biology & medicine 1999-02, Vol.26 (3), p.295-302
Main Authors: Pedulli, Gian Franco, Lucarini, Marco, Marchesi, Emanuela, Paolucci, Francesco, Roffia, Sergio, Fiorentini, Diana, Landi, Laura
Format: Article
Language:English
Subjects:
Antioxidants
Antioxidants - pharmacology
Dipyridamole
Dipyridamole - pharmacology
Electrochemistry
EPR spectroscopy
Free radical
Lipid peroxidation
Molecular Structure
Oxidation-Reduction
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Summary:Very strong medium effects have been observed when testing the antioxidant activity of dipyridamole (DP) in different media such as benzene, tert-butanol, methanol solutions and egg yolk lecithin unilamellar and multilamellar vesicles. Actually, dipyridamole behaves as a very poor antioxidant in benzene while its ability to inhibit the lipid peroxidation reaction increases with increasing solvent polarity, being the highest in lipid vesicles. This behavior can not be rationalized on the basis of the classical chain breaking mechanism which operates in the case of phenolic and amine antioxidants and involving the transfer of a hydrogen atom to peroxyl radicals. An explanation is instead given in terms of an electron transfer reaction which leads to the oxidation of DP by the chain carrying peroxyl radical to give the dipyridamole cation radical, DP + •, and the peroxyl anion LOO −, and whose rate constant is expected to increase in strongly polar media. EPR and electrochemical data supporting this interpretation have been collected.
ISSN:0891-5849
1873-4596
DOI:10.1016/S0891-5849(98)00191-9