title: Antioxidant activity of alpha-pyridoin and its derivatives: possible mechanism.
abstract: alpha-Pyridoin (1, 1,2-di(2-pyridyl)-1,2-ethenediol) is a unique enediol antioxidant. To explore the detailed antioxidant mechanism of alpha-pyridoin, we synthesized alpha-pyridoin and its 5,5'- or 6,6'-bis-substituted derivatives (2-7) and compared their capacities to scavenge galvinoxyl radical (GO*) and protect human red blood cells (RBCs) from oxidative haemolysis. It was found that the compounds (5 and 6) with a methyl or methoxy group at the 5-position exhibit significantly higher GO*-scavenging and anti-haemolysis activities than other derivatives and vitamin C. Kinetic analysis of the GO*-scavenging reaction and the effect of added base on the reaction rate revealed that in ethyl acetate, the reaction occurs primarily by the direct hydrogen atom transfer (HAT mechanism). However, in ethanol that supports ionization, the kinetics of the process is mostly governed by sequential proton loss electron transfer (SPLET mechanism).
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou, Gansu 730000, China.
authors.forename: Li-Xia
authors.initials: LX
authors.lastname: Cheng
authors.forename: Xiao-Ling
authors.initials: XL
authors.lastname: Jin
authors.forename: Qing-Feng
authors.initials: QF
authors.lastname: Teng
authors.forename: Jin
authors.initials: J
authors.lastname: Chang
authors.forename: Xiao-Jun
authors.initials: XJ
authors.lastname: Yao
authors.forename: Fang
authors.initials: F
authors.lastname: Dai
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Qian
authors.forename: Jiang-Jiang
authors.initials: JJ
authors.lastname: Tang
authors.forename: Xiu-Zhuang
authors.initials: XZ
authors.lastname: Li
authors.forename: Bo
authors.initials: B
authors.lastname: Zhou
mesh_terms: D000975:Antioxidants / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D001559:Benzhydryl Compounds / Q000378:metabolism; D004912:Erythrocytes / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D010084:Oxidation-Reduction; D011725:Pyridines / Q000138:chemical synthesis / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: C532526:2,2'-pyridoin; D000975:Antioxidants; D001559:Benzhydryl Compounds; D011725:Pyridines; C020338:galvinoxyl