What question did this study set out to answer?

To measure the rate constants of peroxyl radical hydrogen abstraction for vitamin E tocopherols and elucidate the structural factors governing their antioxidant reactivity.

October 1, 1981Journal of the American Chemical Society

Autoxidation of biological molecules. 1. Antioxidant activity of vitamin E and related chain-breaking phenolic antioxidants in vitro

View Full Paper

Ask AI

Bookmark

Authors

GBGraham W. BurtonSt Thomas' Hospital KIK. U. IngoldUniversity of Minnesota

Discussion

Member takes

Implication

In vitro kinetic study demonstrates rapid peroxyl radical trapping by alpha-tocopherol driven by stereoelectronic stabilization, highlighting its efficacy as a chain-breaking antioxidant.

Key Points

To measure the rate constants of peroxyl radical hydrogen abstraction for vitamin E tocopherols and elucidate the structural factors governing their antioxidant reactivity.
Measured peroxyl radical abstraction rate constants (k5) from tocopherols (alpha, beta, gamma, delta) and phenolic model compounds at 30°C.
Quantified radical stoichiometric factors and assessed deuterium kinetic isotope effects during peroxyl radical reactions.
Performed X-ray crystallographic analysis on model compounds (TMMP, PMHC, and methoxyphenols) to determine stereoelectronic molecular geometry.
Alpha-tocopherol exhibited the highest hydrogen abstraction rate constant at 23.5 × 10^5 M^-1 s^-1, followed by beta- (16.6 × 10^5 M^-1 s^-1), gamma- (15.9 × 10^5 M^-1 s^-1), and delta-tocopherol (6.5 × 10^5 M^-1 s^-1).
Model compound PMHC showed high reactivity (k5 = 21.4 × 10^5 M^-1 s^-1), whereas TMMP exhibited a tenfold reduction in reactivity (k5 = 2.1 × 10^5 M^-1 s^-1).
X-ray crystallography confirmed that the chroman ring locks the ethereal oxygen p-type lone pair perpendicular to the aromatic ring, maximizing phenoxyl radical stabilization.

Cite This Study

Burton et al. (1981) studied this question.

synapsesocial.com/papers/69d774b6db9d5e1bf4b8aa55 https://doi.org/10.1021/ja00411a035

View Full Paper

Ask AI

Bookmark

Implication

In vitro kinetic study demonstrates rapid peroxyl radical trapping by alpha-tocopherol driven by stereoelectronic stabilization, highlighting its efficacy as a chain-breaking antioxidant.

Autoxidation of biological molecules. 1. Antioxidant activity of vitamin E and related chain-breaking phenolic antioxidants in vitro

Discussion

Member takes

Implication

Key Points

Cite This Study

Autoxidation of biological molecules. 1. Antioxidant activity of vitamin E and related chain-breaking phenolic antioxidants in vitro

Discussion

Member takes

Implication

Key Points

Cite This Study

Also Consider

Also Consider