Antioxidants and the Autoxidation of Fats. IX. The Antioxidant Properties of the Tocopherols

Olcott, Henry Steel; Emerson, Oliver H.

doi:10.1021/ja01285a013

Cited by 142 publications

(45 citation statements)

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“…Briefly, 5-ethoxymethyl-2,2, 7,8-tetramethyl-6-hydroxychroman (6), 5-propoxymethyl-2,2,7,8-tetramethyl-6-hydroxychroman (7), 5-buthoxymethyl-2,2,7,8-tetramethyl-6-hydroxychroman (8), and 5-pentyloxymethyl-2,2,7,8-tetramethyl-6-hydroxychroman (9) were prepared by reactions of 2,2,5,7,8-pentamethyl-6-hydroxychroman and the corresponding alcohols using t-butylhydroperoxide according to published methods [14]. 2,2,5,7,8-Pentamethyl-6-hydroxychroman was prepared according to the method of Nilsson et al [15].…”

Section: Experimental D-␣- D-␤- D-␥ - and D-␦-tocsmentioning

confidence: 99%

“…When the autoxidation proceeds and LOOH increases, reaction (8) plays an important role in the pro-oxidant effect of Toc.…”

Section: Loomentioning

confidence: 99%

“…The orders of relative tocopherol (Toc) biopotency using various bioassays [5], scavenging activity of lipid peroxyl radicals by Toc [6], and quenching activity of singlet oxygen by Toc [7] are as follows: ␣-Toc > ␤-Toc ≥ ␥ -Toc > ␦-Toc. On the other hand, the reverse is the case for the activity to protect fats and oils from oxidation [8,9]: ␣-Toc < ␤-Toc < ␥ -Toc < ␦-Toc. The reason for this reverse in the antioxidant activities has not been elucidated so far.…”

Section: Introductionmentioning

confidence: 99%

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Why is the order reversed? peroxyl‐scavenging activity and fats‐and‐oils protecting activity of vitamin E

Mukai

Noborio

Nagaoka

2005

Int J of Chemical Kinetics

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The orders of relative tocopherol biopotency, scavenging activity of lipid peroxyl radicals, and quenching activity of singlet oxygen are as follows: α-tocopherol > β-tocopherol ≥ γ-tocopherol > δ-tocopherol. However, the reverse is the case for the activity to protect fats and oils from oxidation: α-tocopherol < β-tocopherol < γ-tocopherol < δ-tocopherol. The reason for this reverse has been studied by measuring weight gains of solutions including methyl linoleate and various antioxidants at daily intervals. Antioxidant activity is expressed as an induction period in days. Induction periods are compared with the second-order rate constants for scavenging of an aroxyl radical by the antioxidants. A plot of the logarithm of the secondorder rate constant vs. the induction period is found to give a good linear fit, and the slope is negative. From these results, it is considered that the larger the peroxyl-radical-scavenging activity of a tocopherol, the more favorable the production of the tocopheroxyl radical, and thus the more efficient the oxidation of fats and oils by the tocopheroxyl radical. This is not the case for tocopherols in vivo, because vitamin C and ubiquinol reduce tocopheroxyl radicals formed from tocopherols. C 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: [605][606][607][608][609][610] 2005

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Section: Experimental D-␣- D-␤- D-␥ - and D-␦-tocsmentioning

confidence: 99%

“…When the autoxidation proceeds and LOOH increases, reaction (8) plays an important role in the pro-oxidant effect of Toc.…”

Section: Loomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Why is the order reversed? peroxyl‐scavenging activity and fats‐and‐oils protecting activity of vitamin E

Mukai

Noborio

Nagaoka

2005

Int J of Chemical Kinetics

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“…The most active form of vitamin E is α-tocopherol, a 6-hydroxychroman derivative with methyl groups in position 2, 5, 7 & 8 and a phytyl side chain attached at carbon 2 7 . Vitamin E is a powerful antioxidant, protects cells from oxidation and neutralizes unstable free radicals, which can cause damage 8 . Vitamin E giving up one of its electron to the electron deficient free radicals making it more stable.…”

Section: Introductionmentioning

confidence: 99%

Untitled

2010

IJPSR

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“…3 Vitamin E is a collective name for a family of compounds including four tocopherols and four tocotrienols. Structurally, they are all 6-chromanols.…”

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confidence: 99%

Regenerable Radical-Trapping Tellurobistocopherol Antioxidants

et al. 2016

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Abstract: Tellurobistocopherols 9-11 were prepared by lithiation of the corresponding bromotocopherols, reaction with tellurium tetrachloride and reductive work-up.Compounds 9-11 quenched linoleic acid-derived peroxyl radicals much more efficiently than -tocopherol in a chlorobenzene/water two-phase system.N-Acetylcysteine or tris(2-carboxylethyl)phosphine as co-antioxidants in the aqueous phase could regenerate the tellurobistocopherols and increase their inhibition times.Antioxidant 11 inhibited peroxidation for seven-fold longer than recorded with -tocopherol. Thiol-consumption in the aqueous phase was monitored and found to be inversely related to the inhibition time.Oxidative stress is characterized by an imbalance between the production of reactive oxygen species (ROS) and the antioxidant defense systems in favour of the former. 1ROS is known to target lipids in biological systems and this is generally known as lipid peroxidation, an undesired free radical process whereby organic substances, RH, are oxidized to the corresponding hydroperoxides, ROOH (eq 1).Vitamin E, the most important lipid-soluble antioxidant in man, offers protection against lipid peroxidation. Briefly, vitamin E (AH) competes with the propagation event and scavenges peroxyl radicals, ROO·, by hydrogen-atom transfer (HAT) with a rate kinh >> kprop (eq 2). The resulting resonance-stabilized radical A· is unable to propagate the reaction.

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Antioxidants and the Autoxidation of Fats. IX. The Antioxidant Properties of the Tocopherols

Cited by 142 publications

References 0 publications

Why is the order reversed? peroxyl‐scavenging activity and fats‐and‐oils protecting activity of vitamin E

Why is the order reversed? peroxyl‐scavenging activity and fats‐and‐oils protecting activity of vitamin E

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Regenerable Radical-Trapping Tellurobistocopherol Antioxidants

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