Kinetic Reaction Mechanism of Sinapic Acid Scavenging NO2 and OH Radicals: A Theoretical Study.
The mechanism and kinetics underlying reactions between the naturally-occurring antioxidant sinapic acid (SA) and the very damaging ·NO2 and ·OH were investigated through the density functional theory (DFT). Two most possible reaction mechanisms were studied: hydrogen atom transfer (HAT) and radical adduct formation (RAF). Different reaction channels of neutral and anionic sinapic acid (SA-) scavenging radicals in both atmosphere and water medium were traced independently, and the thermodynamic and kinetic parameters were calculated. We find the most active site of SA/SA- scavenging ·NO2 and ·OH is the -OH group in benzene ring by HAT mechanism, while the RAF mechanism for SA/SA- scavenging ·NO2 seems thermodynamically unfavorable. In water phase, at 298 K, the total rate constants of SA eliminating ·NO2 and ·OH are 1.30×108 and 9.20×109 M-1 S-1 respectively, indicating that sinapic acid is an efficient scavenger for both ·NO2 and ·OH.
College of Material Science and Engineering, Harbin University of Science and Technology, Harbin, People's Republic of China.
Yang
Y
Lu
College of Material Science and Engineering, Harbin University of Science and Technology, Harbin, People's Republic of China.
AiHua
A
Wang
College of Material Science and Engineering, Harbin University of Science and Technology, Harbin, People's Republic of China.
Peng
P
Shi
College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin, People's Republic of China.
Hui
H
Zhang
Key Laboratory of Cluster Science of Ministry of Education & School of Chemistry, Beijing Institute of Technology, Beijing, People's Republic of China.
ZeSheng
Z
Li
D000975:Antioxidants / Q000378:metabolism*; D003373:Coumaric Acids / Q000378:metabolism*; D016166:Free Radical Scavengers / Q000378:metabolism; D017665:Hydroxyl Radical / Q000378:metabolism*; D007700:Kinetics; D008954:Models, Biological; D009569:Nitric Oxide / Q000378:metabolism*; D026361:Reactive Nitrogen Species / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013816:Thermodynamics
D000975:Antioxidants; D003373:Coumaric Acids; D016166:Free Radical Scavengers; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D017665:Hydroxyl Radical; C073734:sinapinic acid