Vitamin E

Abstract

The term vitamin E is used to describe eight lipophilic, naturally occurring compounds that include four tocopherols and four tocotrienols designated as alpha-, beta-, gamma-, and delta-. The most well-known function of vitamin E is that of a chain-breaking antioxidant that prevents the cyclic propagation of lipid peroxidation. Despite its antioxidant function, dietary vitamin E requirements in humans are limited only to alpha-tocopherol because the other forms of vitamin E are poorly recognized by the hepatic alpha-tocopherol transfer protein (TTP), and they are not converted to alpha-tocopherol by humans. In attempts to gain a better understanding of vitamin E's health benefits, the molecular regulatory mechanisms of vitamin E have received increased attention. Examples of these mechanisms include: (1) the role of the hepatic alpha-TTP in preferentially secreting alpha-tocopherol into the plasma, (2) phase I and phase II metabolism of vitamin E and the potential impact for drug-vitamin E interactions, and (3) the regulation of biliary excretion of vitamin E by ATP-binding cassette protein(s). It is expected that the continued studies of these regulatory pathways will provide new insights into vitamin E function from which additional human health benefits will evolve.

Effects of lead exposure on oxidative stress biomarkers and plasma biochemistry in waterbirds in the field

“…This effect may be owing to a response of the organism to cope with the oxidative stress generated by Pb poisoning. Vitamin E can be mobilized from the liver to maintain plasma levels for delivery to other tissues (Bartlett et al, 1974;Mustacich et al, 2007). Under oxidative stress, the erythrocytic membranes are susceptible to lipid peroxidation, which has been associated with the hemolytic action of heavy metal ions (Gurer and Ercal, 2000).…”

Short-term alpha- or gamma-delta-enriched tocopherol oil supplementation differentially affects the expression of proinflammatory mediators: selective impacts on characteristics of protein tyrosine nitration in vivo

“…The α-isoform of tocopherols is considered the most biologically relevant, specified in terms of recommendation for daily allowances, [23][24][25]39,40 and, for the most part, principally studied. Increasingly, however, it is recognized that the different tocopherol isoforms have biochemical impacts beyond antioxidant status, 41,42 many of which even can be further traced to impacts on gene expression either directly, 43 or via ONOO -modification of regulatory elements.…”

INTERRELATION OF VITAMIN E ISOFORMS AND ATHEROGENESIS MARKERS IN PATIENTS WITH TYPE 2 DIABETES MELLITUS (literature review and own results)

“…Термiн вiтамiн Е використовують стосов-но восьми спорiднених сполук природного (рослинного) походження, до яких належать чотири токоферола (насиченi форми вiтамi-ну Е) та чотири токотриєнола (ненасиченi форми вiтамiну Е з iзопреноїдним боковим ланцюгом), позначенi як α-, β-, γ-та δ- [2].Натепер є достатня кiлькiсть доказiв се-лективного накопичення α-токоферолу та, у значно меншiй кiлькостi, γ-токоферолу у плазмi та тканинах ссавцiв [2][3][4][5]. Це, в пер-шу чергу, пов'язано зi слабким розпiзна-ванням iнших форм вiтамiну Е печiнко-вим α-токоферол-транспортним протеїном, що веде до їх достатньо швидкої елiмiна-цiї з кровоплину.…”

“…Натепер є достатня кiлькiсть доказiв се-лективного накопичення α-токоферолу та, у значно меншiй кiлькостi, γ-токоферолу у плазмi та тканинах ссавцiв [2][3][4][5]. Це, в пер-шу чергу, пов'язано зi слабким розпiзна-ванням iнших форм вiтамiну Е печiнко-вим α-токоферол-транспортним протеїном, що веде до їх достатньо швидкої елiмiна-цiї з кровоплину.…”