Vitamin E, α-Tocopherol
Ruth G. Alscher, John L. Hess in Antioxidants in Higher Plants, 2017
Vitamin Ε belongs to a family of antioxidants that includes four methylated tocols, substituted with a phytyl chain, and the analogous tocotrienols, substituted with a geranylgeranyl chain (Figure l).2,14 Of the tocopherols, vitamin E, is the major constituent and contains the fully substituted benzoquinone ring, and is identified as 5,7,8-trimethyl tocol. The β-tocopherol (5,8-dimethyl tocol) and γ-tocopherol (7,8-dimethyl tocol) may exist as intermediates in the synthesis of vitamin Ε from the common precursor, δ-tocopherol (8-methyl tocol) (Figure 3). Although one might interconnect the pathways for the biosynthesis of these two classes of antioxidants,20 it is likely that there are similar but distinct methylation and cyclization steps for the synthesis of the tocols and the tocotrienols. Their synthesis may depend on both the site of synthesis and the availability of either phytyl pyrophosphate or geranylgeranyl pyrophosphate. The committed step for tocopherol biosynthesis is catalyzed by homogentisate decarboxylase phytyltrans-ferase.21 It is this cyclization step that forms the physiologically active d-isomer of the tocochromanols.
Fat-Soluble Vitamins
Luke R. Bucci in Nutrition Applied to Injury Rehabilitation and Sports Medicine, 2020
Major dietary sources for vitamin E are wheat germ oil, rice bran oil, wheat germ, vegetable oils, nuts, seeds, cereals, and green leafy vegetables.505,509 The two oils most consumed in the U.S., soybean and corn oils, have very little d-α-tocopherol content, but rather have mostly d-δ-tocopherol content. With increasing usage of vitamin E as a food preservative and additive, vitamin E contents of prepared foods can vary widely. Some foods show seasonal variation of vitamin E contents. Many processes can destroy vitamin E in foods. The list includes exposure to air (oxidation), drying in presence of air and sunlight, addition of organic acids, milling, refining of grains and oils, irradiation, canning, and exposure to peroxidized (rancid) lipids.509 Natural sources of tocopherols are always unesterified, while natural sources of tocotrienols are sometimes esterified. Since plants, but not animals, synthesize vitamin E, animal foodstuffs have very low levels of vitamin E.
Role of Lactic Acid Bacteria in Impacting Nutrient Bioavailability
Marcela Albuquerque Cavalcanti de Albuquerque, Alejandra de Moreno de LeBlanc, Jean Guy LeBlanc, Raquel Bedani in Lactic Acid Bacteria, 2020
Fermentation can change the vitamin content of legumes and legume-based food products such as the amounts of B vitamins, vitamin C, and tocopherol. These differences in vitamin content with fermentation may be due to the microbes used—some synthesize certain nutrients, some degrade them—as well as the substrate. A 2017 review found that fermentation with fungi as well as with L. acidophilus increased “thiamin, riboflavin, niacin or pyridoxine in soymilk” but also decreased the vitamin C content in soymilk as well as lupin seeds. Fermentation increased vitamin C content of red beans. Fermenting soy with L. plantarum or with autochthonous bacteria (natural fermentation) decreased the α-, β-, and γ-tocopherol content, but increased the δ-tocopherol content (Gan et al. 2017). Lupins fermented with L. plantarum, however, had lower tocopherol levels for all tocopherol homologs (α-, γ-, and δ-tocopherol) (Gan et al. 2017). Fermentation with L. delbrueckii sp. bulgaricus increased the vitamin E content of red beans (Gan et al. 2017). These results are based on a limited pool of studies, however, more directed research is needed to determine mechanisms for the impact of fermentation with different LAB on different legumes as well (Gan et al. 2017).
The Potential Physiological Role of γ-Tocopherol in Human Health: A Qualitative Review
Published in Nutrition and Cancer, 2020
Mika D. Thompson, Robert V. Cooney
Tocopherols are lipid-soluble compounds that consist of a chromanol ring and a 16 carbon, phytyl side chain with a varying number of methyl groups on the chromanol ring. Based on the methylation of the chromanol ring, tocopherols are designated as α-, β-, γ-, and δ-tocopherol (Figure 1). For example, γ-tocopherol is dimethylated at the 7- and 8-positions, whereas α-tocopherol is trimethylated at the 5-, 7-, and 8-positions, along the chromanol ring. Naturally occurring tocopherols have three chiral centers in the RRR configuration at the 2, 4, and 8 positions. Tocopherols are typically found in the lipid fractions of seeds and nuts and oils. To the best of our knowledge, there is no up-to-date description of the contemporary γ-tocopherol content of the American diet; however, in the 1970’s, the American diet, relying heavily on corn and soybean oils, has been described as especially high in γ-tocopherol (86). Assuming no decreased intake since the 1970’s means that γ-tocopherol may still constitute the majority of the tocopherols consumed (87). Additionally, walnuts, peanuts, and sesame seeds, along with their oils, are also significant sources of γ-tocopherol in the diet (88).
First report on the presence of aflatoxins in fig seed oil and the efficacy of adsorbents in reducing aflatoxin levels in aqueous and oily media
Published in Toxin Reviews, 2022
Tocopherols were determined according to the AOCS Official Method Ce 8–89 (AOCS 2009) with a slight modification. Briefly, 0.25 g of fig seed oil sample was diluted with 1 ml of 2-propanol, filtered through a microfilter with a pore size of 0.45 µm (Chromafil Xtra PTFE-45/25, Macherey-Nagel, Duren, Germany) and injected to the HPLC. Analytical column was Zorbax Eclipse XDB-C18 column (Agilent Technologies, 250 mm × 4.6 mm I.D., 5 μm particle diameter, Santa Clara, USA), column temperature was 25 °C and the injection volume was 20 µL. The mobile phase was HPLC grade methanol with a flow rate of 1 ml/min. Detection was carried out at 289 nm for alpha-tocopherol and 297 nm for delta-tocopherol and gamma-tocopherol using a photodiode array detector (Shimadzu SPD-M20A, Kyoto, Japan). Standard solutions of alpha-, delta- and gamma-tocopherols were separately prepared in ethanol using analytical standards of these compounds (Supelco, Sigma-Aldrich, Bellefonte, CA, USA) and 6-point calibration curves (0.25–25 mg/L for alpha-tocopherol, 1–50 mg/L for delta-tocopherol and 5–500 mg/L for gamma-tocopherol) were drawn. Quantification of the tocopherols in the samples was performed using these curves.
Vitamin E for the management of major depressive disorder: possible role of the anti-inflammatory and antioxidant systems
Published in Nutritional Neuroscience, 2022
Luana M. Manosso, Anderson Camargo, Alcir L. Dafre, Ana Lúcia S. Rodrigues
Vitamin E is a fat-soluble vitamin that was discovered in 1922 [8]. Nowadays, eight chemically different analogs of this vitamin have been reported to be present in food, alpha (α), beta (β), gamma (γ) and delta (δ)-tocopherol and α-, β-, γ- and δ-tocotrienols [9]. Tocopherols and tocotrienols have a similar structure that includes a hydrophilic chromanol ring and an isoprenoid side chain. The difference between them is that tocopherol has a saturated chain, whereas tocotrienol has an unsaturated chain. The differences between the tocopherol analogous α, β, γ, and δ are the number and location of methyl groups in the chromanol ring [10,11]. Among the eight analogs of vitamin E, α-tocopherol is the most abundant in foods and the primary source of this vitamin. Most notable among the food sources of vitamin E are vegetable oils, seeds (especially almonds, peanuts, and sunflower), breakfast cereals fortified with vitamin E, eggs, and some fruit and vegetables [12,13], as shown in Figure 1. According to ‘Dietary Reference Intakes’ the recommended daily intake of vitamin E for an average-sized adult is 15 mg [14].
Related Knowledge Centers
- Chemical Compound
- Tocopherol
- Vitamin E
- Food Additive
- E Number
- Β-Tocopherol
- Γ-Tocopherol