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At least 19 recordsLinked to original sources
PubMed1978

Effect of administration of alpha- and gamma-tocopherol on tissue distribution and red cell hemolysis in rats.

Four groups of rats fed a tocopherol-free diet from weaning were administered, orally, 1.5 mg/day of either alpha- or gamma-tocopherol for 12 weeks or 5 mg/day of these compounds for 6 weeks. The fifth group was continued on the tocopherol-free diet. At the end of the experimental period the concentration of the two tocopherols was measured in plasma, RBC, liver, kidney, heart, spleen, muscle, testes and lungs. At the lower dose levels alpha-tocopherol, but not gamma-tocopherol, protected the RBC from hemolysis. At the higher levels both compounds were effective in this respect. While liver and spleen appeared to be the preferred storage tissues for both alpha- and gamma-tocopherols, a considerable amount of these compounds were found in RBC, muscle, heart and lung. The content of alpha-tocopherol in the liver was significantly greater than that of gamma-tocopherol. Whether this difference is the reflection of preferential utilization of gamma-tocopherol remains to be determined. The other tissues showed a more or less equal accumulation of the two compounds. At the higher levels of supplementation with the tocopherols the accumulation of gamma-tocopherol in most tissues was significantly greater than that of alpha-tocopherol.

Animals↗
PubMed1992

Isolation and properties of gamma-tocopherol methyltransferase in Euglena gracilis.

Gamma-Tocopherol methyltransferase (EC2.1.1.-), which catalyzes the conversion of gamma-tocopherol into alpha-tocopherol, was present in a cell homogenate of Euglena gracilis. The enzyme was loosely bonded to the outer membrane of chloroplasts and solubilized from chloroplast membranes by a detergent, followed by partial purification in a three-step procedure. The methyltransferase showed a pH optimum of 7.5 and a temperature optimum of 35 degrees C and had an M(r) of 150,000. The activity was about 1.4-fold higher with gamma-tocopherol than with beta-tocopherol as substrate. The enzyme was specific for S-adenosylmethionine as a methyl donor, with a Km value of 50 microM. The addition of homogentisate, L-tyrosine and L-phenylalanine into a suspension of Euglena cells increased the relative pool sizes of alpha- and gamma-tocopherol, but not those of beta- and delta-tocopherol. The contents of alpha- and gamma-tocopherol in a chloroplast fraction of Euglena were always higher than those of any other fraction after any period of incubation with homogentisate. Based on the results of the present experiments, we propose a biosynthetic pathway of alpha-tocopherol in Euglena gracilis.

Animals↗
PubMed1976

Relative activity of alpha-tocopherol and gamma-tocopherol in preventing oxidative red cell hemolysis.

The purpose of this study was to compare the antioxidant activities of alpha-tocopherol and gamma-tocopherol in protecting the red cell membrane against lipid peroxidation. Tocopherols were incorporated into the red cell membrane by incubating cells with solutions of the tocopherols in bovine albumin. The cells were then washed and subjected to the dialuric acid hemolysis test. Analysis of variance of the response curves revealed that gamma-tocopherol had 38% of the activity of alpha-tocopherol. No evidence was found for an interaction between the two tocopherols when present in the red cell membranes simultaneously.

Animals↗
PubMed1979

Measurement of alpha-, beta-, and gamma tocopherol in serum by liquid chromatography.

A liquid-chromatographic assay for alpha, beta, and gamma-isomeric tocopherols in human serum is reported. The tocopherols and the internal standard (tocol) are absorbed into a silica gel column and are eluted in less than 10 min with n-hexane/isopropanol (99.4/0.6, by vol) at a flow rate of 1 mL/min. The complete analysis requires no longer than 30 min. Within-day precision (CV) was 1.4% (mean = 13.18 mg/L, n = 24), 7.4% (mean = 0.214 mg/L, n = 14), and 1.3% (mean = 1.01 mg/L, n = 14) for alpha-, beta-, and gamma-tocopherol, respectively. Day-to-day precision (CV) was 4.4% (mean = 9.85 mg/L, n = 10) for alpha-tocopherol, 9.1% (mean = 0.222 mg/L, n = 20) for beta-tocopherol, and 3.8% (mean = 1.00 mg/L, n = 20) for gamma-tocopherol. Extraction recoveries for alpha-, beta-, and gamma-tocopherol averaged 92.4 +/- 2.9% (n = 5), 91.4 4/- 7.6% (n = 5), an 92.0 +/- 4.1% (n = 4), respectively. The smallest injected amount detectable is estimated to be 0.03 micrograms for alpha-, and 0.04 micrograms for beta- and gamma-tocopherol.

Chromatography, High Pressure Liquid↗
PubMed1992

Lipid and tocopherol composition of farm-raised striped and hybrid striped bass.

1. Hybrid striped bass (HB) were heavier and fatter than striped bass (SB) at harvest. 2. Total lipid, triacylglycerol and phospholipid fractions from muscle tissue of HB were characterized as having significantly larger quantities of polyunsaturated fatty acids than SB, while SB contained larger quantities of omega 3 fatty acids (specifically 22:6 and 20:5) than HB. 3. HB muscle tissue contained 14.99 and 11.42 micrograms/g dry weight of alpha- and gamma-tocopherol, respectively, while SB muscle tissue contained 38.77 and 7.15 micrograms/g dry weight of alpha- and gamma-tocopherol, respectively.

Animals↗
PubMed1975

Tocopherols and polyunsaturated fatty acids in human tissues.

Five tissues from three adults who died suddenly and three adult cancer victims were analyzed for alpha- and gamma-tocopherols and fatty acids. When compared with two reports in 1949 and 1958, the three presumably normal subjects had alpha-tocopherol concentrations in liver, muscle and adipose tissue in about the same range as earlier, but heart was twice as high and lung was three times higher than earlier. The content of gamma-tocopherol in all tissues was considerably higher than in 1949 or 1958. Tissues from cancer patients were no lower in alpha-tocopherol than tissues from normal subjects. Adipose tissue from three of the six subjects contained linoleic acid exceeding 15 per cent of total fatty acids. Tocopherols in these subjects, expressed on a tissue weight or tissue lipid basis, were not remarkable. The molar ratio of polyunsaturated fatty acids to alpha-tocopherol in heart and lung was calculated and its possible use in evaluating vitamin E status is discussed.

Adipose Tissue↗
PubMed1977

Rat liver alpha-tocopherol binding protein.

1. The properties of rat liver cytoplasmic alpha-tocopherol binding protein have been studied. 2. The binding protein sedimented in the 3 S region of sucrose density gradients, and gel filtration indicated an approximate molecular weight of 30 500. 3. Of the tissues examined by the present assay, binding was detectable only in the liver. 4. Optimal binding was achieved by incubation at 26 degrees C for 4 h and was independent of pH between 7.4 and 9.0. 5. Pronase completely abolished binding. The binding protein was, however, almost completely resistant to trypsin, and unaffected by RNAase, DNAase, triacylglycerol lipase, and phospholipase C. 6. A variety of tocopherol analogues and other lipid-soluble compounds were tested for their ability to compete for binding. Only alpha-tocopherol and to a lesser extent alpha-tocotrienol and gamma-tocopherol exhibited competition. alpha-Tocopherol acetate, alpha-tocopherol quinone and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid had no effect on binding. 7. Tocopherol binding was reversible, and the tocopherol was not metabolized during incubation.

Animals↗
PubMed1976

Autoxidation in milk rich in linoleic acid. II. Modification of the initiation system and control of oxidation.

Factors contributing to the initiation of lipid oxidation in cow's and mare's milk containing high levels of polyunsaturated fatty acids were studied. Addition of H2O2 just after milking, in slight excess of the stoichiometric amounts required to destroy ascorbic acid, delayed the development of oxidized flavours in cow's milk high in linoleic acid. Hydrogen peroxide treatment followed by the addition of alpha-or gamma-tocopherols prevented lipid oxidation in cow's milk even when 0.1 mg Cu/l milk was added. When used separately in the presence of Cu these treatments were ineffective as was butylated hydroxyanisole treatment. The lipid and ascorbic acid in mare's milk were remarkably stable to oxidation. Addition of 0.05 or 0.1 mg Cu/l, ethylenediamine tetraacetic acid, neocuproine, or H2O2 had very little effect on the loss of ascorbic acid and lipid oxidation in mare's milk.

Animals↗
PubMed1975

Distribution of tocopherols in human plasma and red blood cells.

The content of various tocopherols was determined in normal plasma and red blood cells. alpha-Tocopherol concentrations ranged form 6.6 to 15.0 (mean 9.6) mug/ml in plasma and from 0.9 to 1.8 (mean 1.4) mug/ml in red blood cells. gamma-Tocopherol ranged from 0.7 to 2.7 (mean 1.6) mug/ml in plasma and fron 0.1 to 0.4 (mean 0.24) mug/ml in red blood cells. Only a minute amount (smaller than 0.3 mug/ml) of each of alpha-tocotrienol, beta-tocopherol, gamma-tocotrienol and delta-tocopherol was found in plasma but none in red blood cells. No delta-tochotrienol was detected in either plasma or red blood cells. Of the total tocopherols, alpha form accounted 83 per cent in plasma and 87 per cent in red blood cells and gamma from represented 13 per cent in each system. The recovery of added 14-C-alpha-tocopherol averaged 87 per cent and 69 per cent, respectively, for plasma and red blood cells. All alpha-tocopherol in the red blood cells was found to be localized in the membrane fraction.

Carbon Radioisotopes↗
PubMed1977

Biological activity of vitamin E compounds and natural materials by the resorption-gestation test, and chemical determination of the vitamin E activity in foods and feeds.

The biological activity of the tocopherols and tocotrienols has been re-examined by the rat resorption-gestation test. The following values have been obtained (with d,l-alpha-tocopheryl acetate = 100%): d-alpha-tocopherol 80%; d,l-alpha-tocopherol 59%; d-alpha-tocopheryl acetate 136%; d-alpha-tocotrienol 13%; d-beta-tocopherol 45%; d-beta-tocotrienol 4%; d-gamma-tocopherol 13%; d-delta-tocopherol less than 0.4%. The possibility of alpha- and gamma-tocopherol being synergists has been tested, but no significant effect was found. The antioxidants BHT and ethoxyquin were without effect on the utilization of alpha-tocopherol by the rat. After chemical determination of the tocopherols and tocotrienols in foods and mixed feeds, these biological activities were used to calculate the vitamin E activity. For two samples of margarine and two samples of mixed feed, the calculated value of the vitamin E activity after chemical determination of the tocopherols and tocotrienols was compared with the value found by direct bioassay, and reasonably good agreement was found. The authors suggest that determination of vitamin E in foods and feeds as a rule should be carried out as a chemical determination of the individual tocopherols and tocotrienols followed by a calculation of the vitamin E activity from the biological activity of the tocopherols and tocotrienols.

Animal Feed↗
PubMed1979

Tocopherol level in human blood cells.

The study was undertaken on alpha-tocopherol levels, separated from other analogs, in the red blood cells (RBC) of cord blood, premature infants, healthy children and adults as well as in pregnant women, and compared with the plasma levels. 1. The majority of tocopherol found in the RBC was localized in the membranes. 2. Only alpha-tocopherol was found in the RBC, while alpha- and gamma-tocopherol were found in the plasma. 3. Alpha-tocopherol level in the RBC changes during development in parallel with that in the plasma. However, changes in the level in RBC were smaller than those of the plasma. 4. The ratio of alpha-tocopherol level in the RBC to the plasma was higher in the cord blood and premature infants than in the children and adults. 5. With regard to the cases with high plasma tocopherol levels, a different finding was obtained on the RBC level between pregnant women and adults with a large amount of tocopherol. In the latter, high RBC levels were observed as the plasma levels were elevated, while in spite of a high plasma tocopherol level, the lowest RBC levels were found in the pregnant women.

Adolescent↗
PubMed1975

Vitamin E adequacy of vegetable oils.

Young male rats were fed diets containing 20 per cent fat in the form of soybean oil, corn oil, safflower oil, or hydrogenated shortening, and their vitamin E status was assessed for twenty-seven weeks. On the basis of growth rate, in vitro red cell hemolysis, plasma creatine phosphokinase activity, and testicular development, soybean oil, corn oil, and shortening provided adequate vitamin E. Rats fed safflower oil had slight red cell hemolysis but were normal in other respects. When the tocopherols in corn oil were reduced by half, vitamin E status still appeared normal. Tissue levels of alpha- and gamma-tocopherols were determined in all groups, and the limitations of the dietary E:PUFA ratio are discussed.

Animals↗
PubMedDate not supplied

[Use of colour reactions to identify lipid classes, including tocopherols, by thin-layer chromatography].

Colour reactions of different classes and individual lipids of plant origin with organic and inorganic compounds (used as reagents) were studied to identify them in thin-layer silica gel. Some of the reagents (p-dimethyl phenylene diamine, chromotropic acid in H2SO4, Ti(SO4)2 in H2SO4) helped to detect main lipid classes and to identify selectively individual compounds (alpha- and gamma-tocopherols). Hydrochloric p-nitrophenyl diazonium, p-dimethyl aminobenzaldehyde are of interest mainly as group reagents to lipid classes with common properties. The reaction sensitivity is measured in micrograms.

Chromatography, Thin Layer↗
PubMedDate not supplied

Effects of breast cancer treatments on plasma nutrient levels: implications for epidemiological studies.

The interpretation of case-control studies in which blood nutrient levels are examined as etiological factors in cancer is complicated by the possibility that either the disease or its treatment may alter these levels. Circulating levels of selected nutrients were examined prior to diagnostic biopsy and compared with levels 3 to 4 months after diagnosis among 71 women with breast cancer and 95 women with benign breast disease. Among women with benign breast disease or women with breast cancer who were not given postsurgical adjuvant drug therapy, levels of alpha-carotene, lycopene, alpha-tocopherol, cholesterol, and triglycerides did not change over time. In contrast, women who received chemotherapy had increased levels of cholesterol, retinol, and alpha- and gamma-tocopherol, and women on antiestrogen therapy showed increased levels of triglycerides and alpha-tocopherol. Overall, the concentrations of carotenoids (lycopene, alpha-carotene, and beta-carotene) did not change in breast cancer cases, although subgroup analyses showed increased levels of beta-carotene among cases not receiving drug treatment and decreased levels among those receiving antiestrogens. In summary, blood levels of some nutrients did not appear to be affected by breast cancer or its treatments, but changes were noted for levels of plasma lipids, tocopherols, retinol, and beta-carotene. Those investigating the etiological relationship between breast cancer and circulating nutrients need to consider these effects in designing and interpreting epidemiological studies.

Adult↗
PubMedDate not supplied

Simultaneous liquid chromatographic determination of carotenoids, retinoids, and tocopherols in human buccal mucosal cells.

Epidemiological and experimental data have suggested that some micronutrients, including various carotenoids, retinoids, and alpha-tocopherol, may have chemopreventive activity against certain types of human cancer. In order to define the role of these micronutrients in cancer prevention, it is necessary to measure their concentrations in the target tissues, since these are critical to the chemopreventive effect. We have developed a sensitive and reproducible high-performance liquid chromatography procedure for the simultaneous determination of lutein, zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, beta-carotene, cis-beta-carotene, retinol, retinyl palmitate, alpha-tocopherol, and gamma-tocopherol in an easily accessible human target tissue, the buccal mucosal cells. This procedure used a gradient of two mobile phases which consisted of acetonitrile, tetrahydrofuran, methanol, 1% ammonium acetate, and butylated hydroxytoluene (in v/v/v/v/w): mobile phase A, 85:5:5:5:0.05; mobile phase B, 55:35:5:5:0.05. The run time, including reequilibration, was 47 min: from 100% A to 100% B in 27 min, remaining at that mobile phase for 10 min, then back to 100% A at 43 min at a constant flow rate of 1.3 ml/min. The high-performance liquid chromatography effluent was monitored at 300, 325, and 452 nm for tocopherols, retinoids, and carotenoids, respectively, with a photodiode array detector. The average recovery was 83% for lycopene and > 92% for others. The precision of the assay for all the compounds was less than 10% in a 1-month period. The micronutrients were extracted by incubating the cells with protease, followed by vortex mixing with 1% sodium dodecyl sulfate in ethanol containing 0.1% butylated hydroxytoluene, and, finally, hexane extraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Carotenoids↗
PubMed1978

Blood serum tocopherol levels in calves born from cows winter fed hay or grass silage.

Blood serum tocopherol was determined in 44 calves born in the spring from cows that had been fed either timothy grass silage or timothy hay produced in Norther Ontario. On all sampling dates (at birth and at eight, 21, 35 and 60 days of age), calves from the silage group had higher average tocopherol levels than those from the hay group. Studies on serum tocopherol distribution in cows and their calves obtained 60 days after birth from the silage group showed that alpha-tocopherol averaged 85% and beta + gamma-tocopherols 12%. Only trace quantities of delta-tocopherol were detected in the serum of cows but none in those of calves.

Animal Feed↗