4-Mercaptoimidazoles derived from the naturally occurring antioxidant ovothiols 2. Computational and experimental approach of the radical scavenging mechanism.
The radical-scavenging mechanism of fourteen 4-mercaptoimidazoles, derived from the natural family of ovothiols, was studied via a QSAR approach, cyclic voltammetry, ESR and NMR spectroscopy. A significant correlation was found between the DPPH scavenging abilities of test compounds and thermodynamic parameters like overall ease of disulphide formation. The production of a disulphide compound via thiyl radical formation is proposed. Upon DPPH scavenging, hydrogen abstraction from thiols yields transient short-lived thiyl radicals, which were characterised by ESR and rapidly dimerise to form a disulphide compound. Cyclic voltammetry showed that the best DPPH scavengers exhibit low oxidation potentials for their oxidation to disulphides.
Zoete
V
V
Laboratoire de Chimie Organique Physique associée à l'Ecole Nationale Supérieure de Chimie de Lille, ESA CNRS 8009, Villeneuve d'Ascq, France.
Vezin
H
H
Bailly
F
F
Vergoten
G
G
Catteau
J P
JP
Bernier
J L
JL
D000975:Antioxidants / Q000737:chemistry*; D015764:Bepridil / Q000031:analogs & derivatives / Q000737:chemistry; D001713:Biphenyl Compounds; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers; D005609:Free Radicals; D017665:Hydroxyl Radical / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry* / Q000494:pharmacology; D008762:Methylhistidines / Q000737:chemistry*; D015394:Molecular Structure; D010851:Picrates; D013329:Structure-Activity Relationship; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013816:Thermodynamics
D000975:Antioxidants; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D005609:Free Radicals; D007093:Imidazoles; D008762:Methylhistidines; D010851:Picrates; D013438:Sulfhydryl Compounds; C061475:ovothiol A; D017665:Hydroxyl Radical; D015764:Bepridil; C004931:1,1-diphenyl-2-picrylhydrazyl