Distribution Of Α-tocopherol Research Articles

Development of controlled-release antioxidant poly (lactic acid) bilayer active film with different distributions of α-tocopherol and its application in corn oil preservation

The antioxidant poly (lactic acid) bilayer active films with a different distribution of α-tocopherol (TOC) in two layers (outer layer/inner layer: 0%/6%, 2%/4%, 3%/3%, 4%/2%, 6%/0%) were developed. The effects of TOC distribution on the structural, physicochemical, mechanical, antioxidant and release properties of the films and their application in corn oil packaging were investigated. The different distributions of TOC showed insignificant effects on the color, transparency, tensile strength and oxygen and water vapor barrier properties of the films, but it affected the release behavior of TOC from the films into 95% ethanol and the oxidation degree of corn oil. The film with higher TOC in outer layer showed a slower release rate. The corn oil packaged by the film containing 4% TOC in outer layer and 2% TOC in inner layer exhibited the best oxidative stability. This concept showed a great potential to develop controlled-release active films for food packaging.

The Physiological Roles of Vitamin E and Hypovitaminosis E in the Transition Period of High-Yielding Dairy Cows.

Simple SummaryIn high-yield cows, most production diseases occur during transition periods. Alpha-tocopherol, the most biologically active form of vitamin E, declines in blood and reaches the lowest levels (hypovitaminosis E) around calving. Hypovitaminosis E is associated with the incidence of peripartum diseases. Therefore, many studies which have been published for more than 30 years have investigated the effects of α-tocopherol supplementation. This α-tocopherol deficiency was thought to be caused by complex factors. However, until recently, the physiological factors or pathways underlying hypovitaminosis E in the transition period have been poorly understood. In the last 10 years, the α-tocopherol-related genes expression, which regulate the metabolism, transportation, and tissue distribution of α-tocopherol in humans and rodents, has been reported in ruminant tissues. In this paper, we discuss at least six physiological phenomena that occur during the transition period and may be candidate factors predisposing to a decreased blood α-tocopherol level and hypovitaminosis E with changes in α-tocopherol-related genes expression.Levels of alpha-tocopherol (α-Toc) decline gradually in blood throughout prepartum, reaching lowest levels (hypovitaminosis E) around calving. Despite numerous reports about the disease risk in hypovitaminosis E and the effect of α-Toc supplementation on the health of transition dairy cows, its risk and supplemental effects are controversial. Here, we present some novel data about the disease risk of hypovitaminosis E and the effects of α-Toc supplementation in transition dairy cows. These data strongly demonstrate that hypovitaminosis E is a risk factor for the occurrence of peripartum disease. Furthermore, a study on the effectiveness of using serum vitamin levels as biomarkers to predict disease in dairy cows was reported, and a rapid field test for measuring vitamin levels was developed. By contrast, evidence for how hypovitaminosis E occurred during the transition period was scarce until the 2010s. Pioneering studies conducted with humans and rodents have identified and characterised some α-Toc-related proteins, molecular players involved in α-Toc regulation followed by a study in ruminants from the 2010s. Based on recent literature, the six physiological factors: (1) the decline in α-Toc intake from the close-up period; (2) changes in the digestive and absorptive functions of α-Toc; (3) the decline in plasma high-density lipoprotein as an α-Toc carrier; (4) increasing oxidative stress and consumption of α-Toc; (5) decreasing hepatic α-Toc transfer to circulation; and (6) increasing mammary α-Toc transfer from blood to colostrum, may be involved in α-Toc deficiency during the transition period. However, the mechanisms and pathways are poorly understood, and further studies are needed to understand the physiological role of α-Toc-related molecules in cattle. Understanding the molecular mechanisms underlying hypovitaminosis E will contribute to the prevention of peripartum disease and high performance in dairy cows.

Interactions between α-tocopherol and γ-oryzanol in oil-in-water emulsions

The interaction between antioxidants is affected by many factors, such as concentration, ratio and system. In this study, different concentrations of α-tocopherol and γ-oryzanol showed antagonistic effect in the oil-in-water emulsion, and the distribution of α-tocopherol increased in aqueous phase after combined with γ-oryzanol. The concentration could affect the degree of antagonism. According to fluorescence quenching, cyclic voltammetry measurements and the oxidative decomposition of antioxidants during storage, the inhibitory effect of γ-oryzanol on the regeneration of α-tocopherol was proposed to be responsible for the antagonism. This work can provide suggestions for studying the mechanism of antioxidant interaction in emulsion system.

Ethyl cellulose particles loaded with α-tocopherol for inhibiting thermal oxidation of soybean oil

Most endogenous antioxidants degrade and lose efficiency during frying. The study aimed to inhibit thermal oxidation of soybean oil by fabricating α-tocopherol loaded particles with ethyl cellulose (EC) of different viscosity grades (M9, M70 and M200) via anti-solvent method. As the viscosity of ethyl cellulose increased, particle size decreased from micrometer to nanometer. Confocal laser scanning microscope confirmed successful encapsulation and uniform distribution of α-tocopherol in the loaded particles. Differential scanning calorimetry and thermogravimetric analysis demonstrated that loaded particles protected α-tocopherol from oxidation and degradation. Meanwhile, Fourier transformed infrared demonstrated that α-tocopherol interacted with EC through hydrogen bond and hydrophobic effects. With excellent dispersibility in soybean oil, loaded particles effectively inhibited thermal oxidation of soybean oil and loaded M200 nanoparticles was the most effective, which performed far better than tert-butylhydroquinone (TBHQ). Therefore, the nanoparticles offered a promising way to enhance oxidative stability of oils during thermal processing.

The Subcellular Distribution of Alpha-Tocopherol in the Adult Primate Brain and Its Relationship with Membrane Arachidonic Acid and Its Oxidation Products.

The relationship between α-tocopherol, a known antioxidant, and polyunsaturated fatty acid (PUFA) oxidation, has not been directly investigated in the primate brain. This study characterized the membrane distribution of α-tocopherol in brain regions and investigated the association between membrane α-tocopherol and PUFA content, as well as brain PUFA oxidation products. Nuclear, myelin, mitochondrial, and neuronal membranes were isolated using a density gradient from the prefrontal cortex (PFC), cerebellum (CER), striatum (ST), and hippocampus (HC) of adult rhesus monkeys (n = 9), fed a stock diet containing vitamin E (α-, γ-tocopherol intake: ~0.7 µmol/kg body weight/day, ~5 µmol/kg body weight/day, respectively). α-tocopherol, PUFAs, and PUFA oxidation products were measured using high performance liquid chromatography (HPLC), gas chromatography (GC) and liquid chromatography-gas chromatography/mass spectrometry (LC-GC/MS) respectively. α-Tocopherol (ng/mg protein) was highest in nuclear membranes (p < 0.05) for all regions except HC. In PFC and ST, arachidonic acid (AA, µg/mg protein) had a similar membrane distribution to α-tocopherol. Total α-tocopherol concentrations were inversely associated with AA oxidation products (isoprostanes) (p < 0.05), but not docosahexaenoic acid oxidation products (neuroprostanes). This study reports novel data on α-tocopherol accumulation in primate brain regions and membranes and provides evidence that α-tocopherol and AA are similarly distributed in PFC and ST membranes, which may reflect a protective effect of α-tocopherol against AA oxidation.

Distribution of Eight Vitamin E Homologs Found in 81 Plants Using LC-MS3

To the best of our knowledge, this is the first study to use liquid chromatography/multistage mass spectrometry to demonstrate the distribution of eight vitamin E homologs in plants. Many tocopherol homologs, which showed higher antioxidant activity than tocotrienol homologs, were discovered and α-tocopherol, which had the highest antioxidant activity among these homologs, was widely distributed in all plants. In addition, α-tocopherol occurred at high concentrations in the leaves of plants belonging to the sumac family, which is native to tropical regions. Furthermore, 25.9% of plants contained α-tocopherol alone, whereas the remaining 74.1% contained α-tocopherol in combination with other homologs. The detection frequency was the highest for a combination of α-tocopherol and γ-tocopherol, which is a precursor of α-tocopherol in plants. The highest number of vitamin E homologs was found in leaves, followed by stems, flowers, branches, and buds. Furthermore, tocotrienol homologs were present only in leaves. This indicates that the distribution of homologs in plants reflects the intensity of the antioxidant activity of homologs. It also suggests that the distribution of α-tocopherol in combination with γ-tocopherol is influenced by the α-tocopherol synthetic pathway in plants.

Dynamic regulation of hepatic vitamin E secretion by the α‐tocopherol transfer protein (LB410)

Vitamin E, a plant‐derived neutral lipid, is an essential nutrient for all vertebrates that scavenges free radicals in biological membranes, thereby preventing oxidative stress. Of the eight naturally‐occurring forms of vitamin E, α‐tocopherol is the most biologically active. This discrimination is achieved by the selective retention of α‐tocopherol by the hepatic α‐tocopherol transfer protein (α‐TTP), and by the selective degradation of other vitamin E isoforms by the hepatic cytochrome P450 CYP4F2. In hepatocytes, α‐TTP facilitates the secretion of α‐tocopherol to the circulation for uptake by extrahepatic target tissues. α‐TTP has also been shown to bind to phosphatidylinositol phosphates in vitro, which may constitute a mechanism for regulation of the protein’s activity. We aim to understand how the actions of α‐TTP are regulated in vivo. Specifically, we study how α‐tocopherol status affects the intracellular localization of α‐TTP, and whether phosphorylation of tyrosines in α‐TTP affects it activity. Using live‐cell fluorescence imaging, we found that localization of α‐TTP in hepatocytes is dynamic: in the absence of α‐tocopherol, the protein is found in a punctate perinuclear pattern, but upon addition of vitamin E, the protein redistributes to a diffuse cytosolic pattern. In addition, we found that tyrosine residue(s) of α‐TTP are phosphorylated, and that this modification is necessary for α‐TTP’s activity. These findings suggest that trans‐localization and tyrosine phosphorylation of α‐TTP are regulated under physiological conditions. Thus, dynamic and homeostatic mechanisms regulate the body‐wide distribution of α‐tocopherol.

Rapid determination of α‐tocopherol in cereal grains using dispersive liquid–liquid microextraction followed by HPLC

The traditional for the determination of α-tocopherol in cereal grains includes saponification of a sample followed by liquid-liquid extraction, and it is time- and solvent consuming. In this study, a dispersive liquid-liquid microextraction (DLLME) method was developed to extract α-tocopherol in situ from the saponified grain sample solution. The DLLME experimental parameters including the type and volume of extractants, the volume of dispersers, the addition of salt and the extraction/centrifuging time were examined and optimized. The recommended analytical procedure showed excellent precision (relative SDs of the α-tocopherol amount of 3.1% over intraday and 7.2% over interday), high sensitivity (the detection limit of 1.9 ng/mL), and strong recovery values (88.9-102.5%). In addition, statistical analyses showed no significant difference between the detected amounts of α-tocopherol found by the standardized method and this new procedure. The method was successfully applied to determining the amounts and distribution of α-tocopherol in 14 cereal grain samples.

α‐Tocopherol binding to human serum albumin

Given the ability of human serum albumin (HSA) to bind hydrophobic ligands, the binding mode of α-tocopherol, the most representative member of the vitamin E family, is reported. α-Tocopherol binds to HSA with Kd0 = (7.0 ± 3.0) × 10(-6) M (pH 7.2, 25.0°C). Competitive and allosteric modulation of α-tocopherol binding to full-length and truncated (Asp1-Glu382) HSA by endogenous and exogenous ligands suggests that it accommodates preferentially in the FA3-FA4 site. As HSA is taken up into cells, colocalizes with the α-tocopherol transfer protein, and contributes to ligand secretion via ABCA1, it might participate in the distribution of α-tocopherol between plasma, cells, and tissues.

Seasonal Changes of α‐Tocopherol in Green Marine Algae (Caulerpa genus)

Marine algae are a promising source of beneficial compounds for human use. Among these, pro-vitamin A carotenoids and vitamins B, C, and E stand out. The objective of this study was to investigate seasonal variation of α-tocopherol levels in 5 species of green marine algae of the Caulerpa genus. This research was carried out with both fresh and dry specimens; and, in addition, differences arising as a result of the drying process were examined. Analyses were carried out by high-performance liquid chromatography (HPLC) using an isocratic system and a reversed-phase C-18 column. The distribution of α-tocopherol throughout the year in Caulerpa genus was variable. All samples of both fresh and dried algae contained α-tocopherol, except for the dried C. racemosa from March 2006. The drying process was responsible for losses of α-tocopherol ranging from 21% to 93%.

Effects of Temperature and Emulsifier Concentration on α-Tocopherol Distribution in a Stirred, Fluid, Emulsion. Thermodynamics of α-Tocopherol Transfer between the Oil and Interfacial Regions

The combined linear sweep voltammetry (LSV)/pseudophase kinetic model method was used to obtain the first estimates of the free energies, enthalpy, and entropies of transfer of alpha-tocopherol (TOC) between the oil and interfacial regions of fluid, opaque, emulsions of n-octane, acidic water, and the nonionic surfactant hexaethyleneglycol mono dodecyl ether (C12E6) from the temperature dependence of TOC's partition constant. Determining structure-reactivity relationships for chemical reactions in emulsions is difficult because traditional methods for monitoring reactions are unsuitable and because the partitioning of reactive components between the oil, interfacial, and aqueous regions of opaque emulsions are difficult to measure. The dependence of the observed rate constant, k(obs), for the reaction of an arenediazonium probe, 16-ArN2+, with TOC was determined as a function of C12E6 volume fraction. The pseudophase kinetic model was used to estimate the interfacial rate constant, k1, and the partition constants of antioxidants between the oil and interfacial, Po(I), regions in the emulsion from k(obs) versus phiI profiles. The thermodynamic parameters of transfer from the oil to the interfacial region at a series of temperatures were respectively obtained from the PoI values (deltaGT0,O-->I), by the van't Hoff method (deltaHT0,O-->I), and from the Gibbs equation (deltaST0,O-->I). The free energy of transfer is spontaneous, and a large positive entropy of transfer dominates a positive enthalpy of transfer, indicating that the TOC headgroup disrupts the structure of the interfacial region in its immediate vicinity upon transfer from n-octane. The methods described here are applicable to any bimolecular reaction in emulsions in which one of the reactants is restricted to the interfacial region and the rate of its reaction with a second component can be monitored electrochemically.

Quantitative determination of α-tocopherol distribution in a tributyrin/Brij 30/water model food emulsion

Until recently, determining the distribution of antioxidants, AOs, between the oil, interfacial and aqueous regions of opaque emulsions has not worked well because the concentrations of AOs in interfacial regions cannot be determined separately from their concentrations in the oil and water phases. However, our novel kinetic method based on the reaction between an arenediazonium ion and vitamin E, or α-tocopherol, provides the first good estimates for the two partition constants that describe α-tocopherol distribution between the oil/interfacial and water/interfacial regions of tributyrin/Brij 30/water emulsions without physical isolation of any phase. The reaction is monitored by a new derivatization method based on trapping unreacted arenediazonium ion as an azo dye and confirmed by linear sweep voltammetry, LSV. The results by both derivatization and LSV methods are in good agreement and show that α-tocopherol distributes strongly in favor of the interfacial region when the oil is tributyrin, e.g., ca. 90% when the surfactant volume fraction is Φ I = 0.01 . The second-order rate constant for reaction in the interfacial region is also obtained from the results. Our kinetic method provides a robust approach for determining antioxidant distributions in emulsions and should help develop a quantitative interpretation of antioxidant efficiency in emulsions.

Distribution of alpha-tocopherol in fillets of turbot (Scophthalmus maximus) and Atlantic halibut (Hippoglossus hippoglossus), following dietary alpha-tocopheryl acetate supplementation

The present study investigated the distribution of α-tocopherol (vitamin E) in fillets of turbot (Scophthalmus maximus) and Atlantic halibut (Hippoglossus hippoglossus). Turbot and Atlantic halibut were fed commercial diets, supplemented with different levels of α-tocopheryl acetate at the dietary target levels of 100, 500 and 1000 mg α-tocopheryl acetate kg−1 diet. The actual levels were 72, 547 and 969 for turbot, while halibut received 189, 613 and 875 mg α-tocopheryl acetate kg−1 diet. Turbot were fed the diets for 24 weeks, while Atlantic halibut were fed for 20 weeks prior to slaughter. At the end of the feeding periods fish had reached a final weight of around 1 kg. Fish were slaughtered and filleted. From the four fillets obtained per fish, 22 samples were taken from designated areas and analysed for their α-tocopherol content. The average concentrations of α-tocopherol incorporated in turbot and Atlantic halibut increased with increasing levels of α-tocopheryl acetate in the diet. Atlantic halibut had significantly (P < 0.05) more α-tocopherol in positions 2/II and 1/I than in position 9/IX. Turbot had significantly (P < 0.05) more α-tocopherol in position 2/II than in positions 1/I, 4/IV and 11/XI. By mapping α-tocopherol concentrations in fish fillets, a high degree of quality prediction may be established. Moreover, this study may help scientists in their choice of sampling position, when investigating if α-tocopheryl acetate supplementation resulted in successful α-tocopherol incorporation.

The distribution of α-tocopherol in mixed aqueous dispersions of phosphatidylcholine and phosphatidylethanolamine

The effect of α-tocopherol on the structure and phase behaviour of mixed aqueous dispersions of phosphatidylcholine and phosphatidylethanolamine has been examined by synchrotron X-ray diffraction. Equimolar mixtures of dioleoylphosphatidylethanolamine:dioleoylphosphatidylcholine and dimyristoylphosphatidylcholine:dioleoylphosphatidylethanolamine did not show evidence of phase separation of an inverted hexagonal structure typical of α-tocopherol and phosphatidylethanolamine from lamellar phase. Mixed dispersions of dioleoyl derivatives of phosphatidylethanolamine:phosphatidylcholine (3:1) form a typical miscible gel phase at low temperatures but which phase separates into lamellar liquid–crystal and inverted hexagonal phases at temperatures greater than 65°C. The presence of 1, 2 or 5 mol% α-tocopherol caused a decrease in the temperature at which the inverted hexagonal phase appears. Phase separation of non-lamellar phase from lamellar gel phase can be detected in the presence of 7.5 and 10 mol% α-tocopherol, indicating a limited capacity of the phosphatidylcholine to incorporate α-tocopherol into the lamellar domain. A partial phase diagram of the ternary mixture has been constructed from the X-ray scattering data. It was concluded that there is no preferential interaction of α-tocopherol with phosphatidylethanolamine in mixed aqueous dispersions containing phosphatidylcholines.

Tocopherol affinity for serum lipoproteins of Japanese flounder Paralichthys olivaceus during the reproduction period

SUMMARY: Changes in distribution of dietary α-tocopherol at 100 mg per 100 g of diet to organic tissues and to serum lipoproteins were investigated on Japanese flounder Paralichthys olivaceus. α-tocopherol had been transported to and preserved more positively in the gonad during the reproduction period. During maturity serum α-tocopherol had partly combined with the vitellogenin-like parts that diminished after the spawning period. Conversely, serum α-tocopherol after the spawning period partly combined with lipoprotein that increased after the spawning period. The prosperity and decline of different types of lipoproteins induced α-tocopherol distribution changes at the end of the spawning period.

Distribution of α-tocopherol in beef muscles following dietary α-tocopheryl acetate supplementation

The objective of this study was to determine the effect of dietary vitamin E supplementation on the distribution and concentration of α-tocopherol in beef muscles. Crossbred cattle ( n=8) were selected and divided into two groups and fed diets containing 20 (basal) and 3000 mg (supplemented) α-tocopheryl acetate/head/day for 135 days prior to slaughter. Carcasses were split centrally and chilled at 4°C for 10 days. Muscles ( n=16) were identified and removed from the left side of each animal and stored at −20°C until required. Mean α-tocopherol levels in muscles were significantly ( P<0.05) higher in all supplemented muscles with the exception of m. infraspinatis and m. deltoidous compared to controls. Mean α-tocopherol levels in muscles from the supplemented group decreased in the order m. supraspinatis > m. psoas major > m. trapezius > m. gluteus medius > m. triceps caput brachii lumborum > m. rhomboidous > m. seratus ventralis > m. gluteobiceps > m. semitendinosus > m. semimembranosus > m. infraspinatis > m. subscapularis > m. tricepscaputbrachiilaterale > m. deltoidous > m. longissimus thorasis > m. longissimus lumborum. Significant ( P<0.05) differences in α-tocopherol distribution within muscles were observed for supplemented m. psoas major and control m. seratus ventralis (highest levels in posterior ends and lowest in anterior ends) only. However, trends showed definite distribution patterns for other muscles. Levels of α-tocopherol were found to be highest in oxidative muscles ( m. psoas major and m. gluteus medius) and lowest in glycolytic muscles ( m. longissimus thoracis and m. longissimus lumborum) while moderate levels of α-tocopherol occurred in intermediate muscles ( m. semimembranosus).

Molecular Mechanism of Cellular Uptake and Intracellular Translocation of α-Tocopherol: Role of Tocopherol-binding Proteins

Vitamin E ( α-tocopherol) is a lipid-soluble antioxidant which is present in cellular membranes where it plays an important role in the suppression of free radical-induced lipid peroxidation. There are eight naturally occurring homologues of vitamin E which differ in their structure and in biological activity in vivo and in vitro. Various studies have suggested that the tocopherol distribution system favours the accumulation of α-tocopherol both in the plasma and different tissues. Mechanisms involved in the preferential accumulation of α-tocopherol are not yet well established; however, recent data indicate that both intracellular and membrane α-tocopherol-binding proteins may be involved in these processes. A 30 kDa α-tocopherol-binding protein (TBP) in the liver cytoplasm is now known to regulate plasma vitamin E concentrations by preferentially incorporating α-tocopherol into nascent very low density (VLDL) whereas the 15 kDa TBP may be responsible for intracellular distribution of α-tocopherol. The 30 kDa TBP is unique to the hepatocyte whereas the 15 kDa TBP is present in all major tissues. The 15 kDa TBP specifically binds α-tocopherol in preference to the δ- and γ-tocopherol and may exclusively transport α-tocopherol to these intracellular sites. In addition, the presence of a membrane TBP (TBP pm) in tissues may regulate their α-tocopherol levels. Activity of erythrocyte TBP pm appears to be reduced in smokers, which may lead to reduced levels of α-tocopherol in these cells despite smokers have similar plasma levels of vitamin E as in non-smokers. The current status of the evidence for this directed flow of α-tocopherol through interactions with these proteins (TBP and TBP pm) is discussed.

Effect of dietary α-tocopheryl acetate supplementation on α-tocopherol distribution in raw turkey muscles and its effect on the storage stability of cooked turkey meat

Day-old turkey chicks ( n = 99) were divided at random into three groups ( n = 33) and fed diets containing 20 (E20), 300 (E300) and 600 (E600) mg all-rac-α-tocopheryl acetate per kg feed per day for 21 weeks prior to slaughter. After slaughter, breasts and legs were removed and examined for α-tocopherol content. Breast muscle from birds fed the three diets was oven cooked, cooled, sliced and overwrapped. The oxidative and colour stability of the slices was examined. Mean α-tocopherol levels in turkey muscle were significantly ( p < 0.05) higher in the E300 and E600 groups compared to the control group fed the E20 diet. α-Tocopherol levels in the E300 and E600 groups showed that concentrations in leg muscle were significantly ( p <0.05) higher than in breast muscle. α-Tocopherol levels in leg and breast muscles from birds fed E20 and E600 diets decreased significantly (p < 0.05) during 12 months of frozen (−20 °C) storage. TBARS numbers for breast slices from all three dietary groups, cooked both 24 hr after slaughter and following frozen (−20 °C × 11 months) storage, increased during refrigerated (4 °C) display for 10 days. TBARS numbers for slices produced from meat previously held in frozen storage increased more rapidly than those for meat cooked following slaughter. In both cases, E300 and E600 diets significantly ( p < 0.05) suppressed lipid oxidation compared to E20 samples. In general, Hunter a values for meat slices from turkeys fed the E300 and E600 diets were higher than those for meat slices from turkeys fed the E20 diet.

α-Tocopherol levels in different organs of Atlantic salmon (Salmo salar L.)—Effect of smoltification, dietary levels of n-3 polyunsaturated fatty acids and vitamin E

Atlantic salmon ( Salmo salar ) juveniles were fed a basal diet coated with 16% sardine or capelin oil (68 or 42 g n-3 PUFA per kg dry diet, respectively), each supplemented or not with 300 mg dl -α-tocopheryl acetate per kg. The unsupplemented diets contained 28 ± 4 and 31 ± 9 mg/kg α-tocopherol, respectively. There was a 5–7-fold increase in whole body α-tocopherol concentration in response to vitamin E supplementation, but the relative distribution of α-tocopherol between organs was similar in all groups. There was only a weak effect of dietary n-3 PUFA on the tissue levels of α-tocopherol. The ratio of α-tocopherol to PUFA in the fish tissues is probably critical in protection against lipid oxidation, and may modulate the vitamin E requirement. During smoltification, the whole body α-tocopherol concentration was unchanged or slightly increasing. All groups showed a 40–50% reduction of α-tocopherol concentration in the kidney and adipose tissue, possibly linked to changes in osmoregulation and mobilization of vitamin E. The body level of α-tocopherol seems to be higher in fish than in mammals. A species-specific tissue “distribution key” for α-tocopherol appears to be present in several fish and mammal species.

Distribution ofα-Toc Stereoisomers in Rats

The distribution of α-tocopherol (α-Toc) stereoisomers in the tissues of rats fed on diets containing different levels of all-rac-α-tocopheryl acetate was determined by a newly revised HPLC method and compared with that of RRR-α-Toc fed rats. By this method, all-rac-α-Toc in the blood and tissues was completely separated into 2R-isomers (one peak) and 2R-isomers (three peaks). The concentrations of the 2R-isomers of α-Toc in the blood and tissues of the rats in the all-rac-α-tocopheryl acetate group were significantly higher than those of the 2S-isomers. In most tissues, the level of 2S-isomers was in order of SRS> (SSS+SSR)/2 > SRR.In the RRR-α-Toc-fed groups, the concentration of RRR-α-Toc in every tissue depended on the dose of α-Toc. When the concentration of 2R-isomers in the tissues of rats fed on all-rac-α-Toc (100 mg/kg diet) is compared with the concentration of RRR-α-Toc in the tissues of rats fed on RRR-α-Toc (50 mg/kg diet) the concentration of 2R-isomers in every tissue of the former is the s...