阿布茨
特罗洛克
化学
猝灭(荧光)
Trolox当量抗氧化能力
动力学
氧自由基吸收能力
抗氧化剂
自由基离子
苯酚
光化学
氧化还原
有机化学
抗氧化能力
DPPH
荧光
离子
物理
量子力学
作者
Xin Tian,Karen M. Schaich
摘要
Reaction kinetics in the Trolox equivalent antioxidant capacity (TEAC) assay between ABTS+• [2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) cation radical] and compounds with different structure, molecular weight, number of OH groups, and redox potential were investigated by recording loss of ABTS+• absorbance (734 nm) continuously over time. Curves showed six distinguishable kinetic patterns, including both immediate and extended reaction components. Radical quenching rates in the immediate component most relevant to reactions in foods and tissues depended on phenol structure and steric accessibility to the hindered radical, while reaction stoichiometry correlated with the number of phenol groups (>0.81) but not redox potential. Current assay procedures measure antioxidant capacity under conditions not relevant to actual applications and do not determine radical quenching rates. Results raise serious questions regarding the ability of reactions with the hindered ABTS+• to rank actual radical quenching by compounds with different structures and invalidate reporting antioxidant activity as Trolox equivalents.
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