Synergie vitamine E, tocotriénol et sélénium ?

[Nutrimuscle-Conseils]

Diverse cytoprotective actions of vitamin E isoforms- role as peroxyl radical scavengers and complementary functions with selenoproteins
Yoshiro Saito Free Radical Biology and Medicine Volume 175, 1 November 2021, Pages 121-129

Highlights
• The different cytoprotective actions of vitamin E isoforms against oxidative stress.
• The complementary role of vitamin E and selenoproteins to prevent lipid peroxidation and ferroptosis.
• The limited role of vitamin E as a peroxyl radical scavenger, based on kinetic data and the physiological molar ratio.

Vitamin E, a generic term for tocopherol (T) and tocotrienol (T3), is one of the most potent lipid-soluble antioxidants in the body. It is classified into T and T3 based on the difference in the side chain structure. T and T3 have four isoforms: α-, β-, γ-, and δ, which have different chroman rings. Both T and T3 exhibit a similar ability to scavenge free radicals, and the extent of this ability depends on the difference in the chroman structure. However, they display unique cytoprotective activities in cultured cells depending on the difference in the side chain structure.

The cytoprotective effects of vitamin E have received much attention in the prevention of ferroptosis, which is a distinct form of cell death involving iron-dependent lipid peroxidation. This review focuses on the cytoprotective actions of vitamin E isoforms against oxidative stress, particularly the difference between T and T3 and its relation to cellular uptake and distribution. Moreover, the molecular mechanism for cytoprotection of vitamin E oxidation products is explained, and the complementary role of vitamin E and selenoproteins to prevent lipid peroxidation and ferroptosis is described. Furthermore, the evaluation of vitamin E's radical scavenging activity in vivo using oxidative stress markers is discussed, particularly based on kinetic data and the physiological molar ratio of vitamin E to substrates, and the limited role of vitamin E as a peroxyl radical scavenger is described. The future directions and unresolved issues related to vitamin E and lipid peroxidation are also discussed.

[Nutrimuscle-Conseils]

[Nutrimuscle-Conseils]

Reflections on a century of vitamin E research: Looking at the past with an eye on the future
Angelo Azzi Free Radical Biology and Medicine Volume 175, 1 November 2021, Pages 155-160

Highlights
• Only RRR-alpha-tocopherol and no other tocopherols, tocotrienols and tocomonoenols have vitamin E function in humans.
• Vitamin E in humans protects against AVED, increases immune response, diminishes inflammation and protects against NASH.
• Vitamin E modulates gene activity in vitro and in vivo.
• Vitamin E metabolism results in biological active molecules like the phosphorylated form and the short chain derivatives.

The name vitamin E, was given by Barnett and Sure who suggested that the factor proposed by Evans and Bishop as substance “X,” be termed vitamin “E“ as the next vitamin after the A, B, C and D vitamins had been already described. The identification of vitamin E with a-tocopherol was made in 1936 by Evans’ group. One year later β-tocopherol and 11 years later δ-tocopherol were isolated. Tocotrienol (named zetatocopherol) was first described in 1957 and later isolated in 1961.

The antioxidant property of tocopherols was reported by Olcott and Emerson in 1937. Inherited vitamin E deficiency, AVED, characterized by a form of neuromyopathy was first described in 1981. The disease, was localized to chromosome 8q and found to be caused by a mutation of the a-TTP gene. The subsequent paragraphs are not a comprehensive review but only critical reflections on some important aspects of vitamin E research.

[Nutrimuscle-Diététique]

Traduction de l'étude

Réflexions sur un siècle de recherche sur la vitamine E : regarder le passé avec un œil sur l'avenir
Angelo Azzi Biologie et médecine des radicaux libres Volume 175, 1er novembre 2021, Pages 155-160

Points forts
• Seul le RRR-alpha-tocophérol et aucun autre tocophérol, tocotriénols et tocomonoénols n'ont de fonction vitamine E chez l'homme.
• La vitamine E chez l'homme protège contre l'AVED, augmente la réponse immunitaire, diminue l'inflammation et protège contre la NASH.
• La vitamine E module l'activité des gènes in vitro et in vivo.
• Le métabolisme de la vitamine E se traduit par des molécules biologiquement actives comme la forme phosphorylée et les dérivés à chaîne courte.

Le nom de vitamine E a été donné par Barnett et Sure qui ont suggéré que le facteur proposé par Evans et Bishop comme substance « X » soit appelé vitamine « E » comme la prochaine vitamine après que les vitamines A, B, C et D aient déjà été décrit. L'identification de la vitamine E avec l'a-tocophérol a été faite en 1936 par le groupe d'Evans. Un an plus tard, le β-tocophérol et 11 ans plus tard le δ-tocophérol ont été isolés. Le tocotriénol (nommé zetatocophérol) a été décrit pour la première fois en 1957 et isolé plus tard en 1961.

La propriété antioxydante des tocophérols a été rapportée par Olcott et Emerson en 1937. La carence héréditaire en vitamine E, AVED, caractérisée par une forme de neuromyopathie a été décrite pour la première fois en 1981. La maladie, localisée sur le chromosome 8q, était causée par une mutation de le gène a-TTP. Les paragraphes suivants ne sont pas une revue complète mais seulement des réflexions critiques sur certains aspects importants de la recherche sur la vitamine E.