Investigation of the antioxidant and radical scavenging activities of some phenolic Schiff bases with different free radicals.
The antioxidant properties of some phenolic Schiff bases in the presence of different reactive particles such as (•)OH, (•)OOH, (CH2=CH-O-O(•)), and (-•)O2 were investigated. The thermodynamic values, ΔH BDE, ΔH IP, and ΔH PA, were used for this purpose. Three possible mechanisms for transfer of hydrogen atom, concerted proton-electron transfer (CPET), single electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) were considered. These mechanisms were tested in solvents of different polarity. On the basis of the obtained results it was shown that SET-PT antioxidant mechanism can be the dominant mechanism when Schiff bases react with radical cation, while SPLET and CPET are competitive mechanisms for radical scavenging of hydroxy radical in all solvents under investigation. Examined Schiff bases react with the peroxy radicals via SPLET mechanism in polar and nonpolar solvents. The superoxide radical anion reacts with these Schiff bases very slowly.
Department of Chemical-Technological Sciences, State University of Novi Pazar, Vuka Karadžića bb, 36300, Novi Pazar, Republic of Serbia. zmarkovic@np.ac.rs.|Bioengineering Research and Development Center, Prvoslava Stojanovića 6, 34000, Kragujevac, Republic of Serbia. zmarkovic@np.ac.rs.
Zoran
Z
Marković
Bioengineering Research and Development Center, Prvoslava Stojanovića 6, 34000, Kragujevac, Republic of Serbia.
Jelena
J
Đorović
Faculty of Science, University of Kragujevac, Radoja Domanovića 12, 34000, Kragujevac, Republic of Serbia.
Zorica D
ZD
Petrović
Faculty of Science, University of Kragujevac, Radoja Domanovića 12, 34000, Kragujevac, Republic of Serbia.
Vladimir P
VP
Petrović
Faculty of Science, University of Kragujevac, Radoja Domanovića 12, 34000, Kragujevac, Republic of Serbia.
Dušica
D
Simijonović
D000975:Antioxidants / Q000737:chemistry*; D004579:Electron Transport; D016166:Free Radical Scavengers / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry*; D021281:Quantitative Structure-Activity Relationship; D012545:Schiff Bases / Q000737:chemistry*; D013816:Thermodynamics
D000975:Antioxidants; D016166:Free Radical Scavengers; D005609:Free Radicals; D010636:Phenols; D012545:Schiff Bases
Antioxidant mechanisms; Antioxidant properties; Density functional theory; Phenolic Schiff bases