Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:EXPT03226 (vitamin E)
 17,558 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two esters of vitamin E, dl-a-tocopheryl nicotinate and dl-a-tocopheryl acetate were found to be more inhibitors than tocopherol itself on platelet aggregation induced by arachidonic acid and collagen. The nicotinate was 1--5 times more potent than the acetate and 2--18 times more potent than the unesterified tocopherol in inhibiting collagen induced aggregation in human citratet platelet-rich plasma.
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PMID:Inhibition of platelet aggregation by alpha-tocopherol and its nicotinate and acetate esters. 71 83

The data in our previous paper demonstrated that some alpha-tocopheryl esters administered orally were absorbed in their unchanged form through the lymph, while some other esters were absorbed after being hydrolyzed individually to different degrees. The hydrolysis during absorption seems to be related to the structure of the ester group of alpha-tocopherol at the 6-position. The purpose of this work is to study the metabolism and biological effect of tocopherol esters in vitamin E-deficient rats. Three esters were used on the basis of their behavior during absorption through the lymph, as follows; alpha-tocopheryl acetate (an easily hydrolyzable ester), the nicotinate (a moderately hydrolyzable one) and the pivalate (a scarcely hydrolyzable one). The easily hydrolyzable esters will suffer the same metabolic fate through absorption as alpha-tocopherol. The moderately and scarcely hydrolyzable ones have a tendency to show different physiological effects from alpha-tocopherol due to absorption of the unchanged ester. The effect of these esters on the microsomal enzymes in the liver such as cytochrome P-450, cytochrome b5, aniline and hexobarbital difference spectra and NADPH-dependent cytochrome c reductase was determined. It was shown that the pivalate inhibited the release of NADPH-dependent cytochrome c reductase activity to supernatant in spite of low distribution in the 105,000 X g sediment. The result suggests that the pivalate as a model compound may be interesting to examine for its membrane stabilizing effect of alpha-tocopherol.
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PMID:Effect of d,l-alpha-tocopheryl esters on vitamin E-deficient rats. 73 32

Hydrogen peroxide can either induce or inhibit or enhance the platelet aggregation in vitro depending upon the experimental conditions. Vitamin E and vitamin E-nicotinate are found to be effective to inhibit, to some extent, the platelet aggregation induced by combined adenosine diphosphate (ADP) and hydrogen peroxide (H2O2), added simultaneously, to the platelet rich plasma (PRP). Vitamin E and vitamin E-nicotinate seemed, however, to be unable to prevent the reduction of platelet response to ADP, which was brought about by the pretreatment of PRP with H2O2 of a lower concentration.
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PMID:Effects of vitamin E on the platelet aggregation induced by combined adenosine diphosphate and hydrogen peroxide. 83 37

The inhibitory effect of vitamin E-nicotinate upon the hydrogen peroxide (H2O2)-induced platelet aggregation was found to be greater than that of either vitamin E alone or the combination of vitamin E and nicotinic acid. Nicotinic acid showed no inhibitory effect. It was suggested that the effect of vitamin E-nicotinate was not due to the additive effect of vitamin E and nicotinic acid produced by hydrolysis, but to the unique and distinctive property of vitamin E-nicotinate itself.
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PMID:A comparative study of the effect of vitamin E-nicotinate and the combination of vitamin E and nicotinic acid on the hydrogen peroxide-induced platelet aggregation. 83 40

We present the dietary epidemiology of bladder cancer while controlling for a number of lifestyle and environmental risk factors in a study of 351 white male cases with histologically confirmed transitional cell carcinoma of the bladder and 855 white male controls selected from Erie, Niagara, and Monroe counties of western New York from 1979 to 1985. Usual diet was estimated by comprehensive interviews with use of a detailed food frequency questionnaire. An increased risk of bladder cancer was associated with higher kilocalorie intake, but only among those under 65 years of age, with the strongest pattern associated with fat intake. Further analyses of fat, carbohydrates, and protein, with adjustment for total kilocalories, resulted in a positive association of risk with fat intake and a decreasing risk with higher protein intake. Of the vitamins, carotenoid consumption appeared to decrease risk with increased consumption for those under 65 years of age. No significant differences between cases and controls were seen for intake of calcium, retinol, thiamin, riboflavin, niacin, vitamin C, vitamin D, and vitamin E. After adjustment for kilocalories and other confounders, higher intake of dietary sodium was associated with increased risk among both age groups, and the trends were statistically significant. The importance of diet in the etiology of bladder cancer is suggested by our findings.
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PMID:Diet in the epidemiology of bladder cancer in western New York. 129 99

The present study analyzes the influence of the nutritional status on the functional capability of 11 institutionalized elderly living in Madrid (Spain). Nutritional status was evaluated by dietetic, anthropometric, hematological and biochemical data and functional status was evaluated considering adiposity, strength in hands and legs bent and stretched and flexibility. The most important nutritional problems that conditional functional wastages are obesity, hypercholesterolemia and protein and micronutrient deficiency. The adverse influence of obesity and hypercholesterolemia on the functional capacity of the elderly is shown by the inverse relationship between flexibility and strength in hands and legs with the adiposity degree, with the thickness of skin folds and the cholesterolemia. In reference to the diet's influence, there are positive correlations between food intake and most of the nutrients with hand and legs strength, and there are statistical significances for proteins, iron, zinc, magnesium and pyridoxine, and also for vitamin C, niacin, thiamin, folic acid and vitamin E. For blood values, the mayor correlation exists between functional parameters and iron, ferritin and vitamin C levels. Our results contribute to confirm the influence of nutrition on the functional capacity of the influence of nutrition on the functional capacity of the elderly and manifest the necessity of improving the elderly's diet, to prevent micronutrient deficiency and also the necessity of increasing their physical activity. Both measures will mean an important help for sanitary and functional improvement of the elderly.
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PMID:[Effect of nutrition on the functional capacity of a group of elderly Spaniards]. 134 53

Tocopherol has been shown to have antiplatelet effects in insulin-dependent diabetes mellitus. However, its antiplatelet effect in non-insulin-dependent diabetes mellitus (NIDDM) remains to be established. In this report, the antiplatelet effect of tocopherol was assessed in a randomized, double-blind and crossover study of 15 NIDDM subjects. Each subject received tocopherol (dl-alpha-tocopherol nicotinate, 200 mg, tid) and a placebo for two six-week treatment periods separated by a three-week period in between for wash-out. The mechanisms of the antiplatelet effect of tocopherol were also studied in vitro. A significant decrease in platelet reactivity was observed after tocopherol treatment as compared with the pretest, and the magnitude of the decrease during tocopherol treatment was significantly evident when compared with that of the placebo treatment, as assessed by collagen (5, 10 micrograms/mL)-induced platelet aggregation of whole blood. A dose-dependent reduction in both ADP-and collagen-induced platelet aggregation was observed with tocopherol from 0.1 to 3.0 mM in vitro. No corresponding changes in ATP secretion and thromboxane synthesis were observed. Tocopherol also significantly inhibited fibrinogen-induced aggregation of elastase-treated platelets at a concentration of 0.1 mM. We demonstrated that platelet aggregation of whole blood ex vivo, among 15 NIDDM subjects was suppressed in tocopherol treatment, so tocopherol may have an antiplatelet effect in NIDDM subjects. The inhibitory effect of the platelet aggregation of tocopherol may be partially accomplished through interference with fibrinogen binding towards its receptor.
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PMID:Effect of tocopherol on platelet aggregation in non-insulin-dependent diabetes mellitus: ex vivo and in vitro studies. 135 87

Many animal and in vitro experiments have shown that the supplementation of diet with vitamin E within a certain dose range reduced the risk of chemical- and radiation-induced cancers. In vitro studies revealed that alpha-tocopheryl succinate (TS) induced differentiation and growth-inhibition in certain animal and human tumor cells in culture, whereas alpha-tocopherol (alpha-T), alpha-tocopheryl acetate (alpha-TA) and alpha-tocopheryl nicotinate (alpha-TN) were ineffective, alpha-TS also reduced basal and ligand-stimulated adenylate cyclase activity, and expression of c-myc and H-ras oncogenes in certain tumor cells in culture. The relative efficacy of various forms of vitamin E in cancer prevention in animal or human models has not been evaluated. Human epidemiologic studies utilizing retrospective and prospective case-control experimental designs are not suitable for evaluating the role of vitamin E in cancer prevention due to several inherent problems associated with these methodologies. Intervention trials utilizing vitamin E with appropriate biological and statistical rationales are most suitable for testing the role of vitamin E in cancer prevention in humans. Some human trials utilizing vitamin E alone or in combination with other nutrients are in progress.
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PMID:Vitamin E and cancer prevention: recent advances and future potentials. 840 88

A study was carried out to assess the bioavailabilities of several forms of vitamin E in lambs. A total of 40 lambs was allotted to eight dietary groups of five each and supplemented or not daily for 60 d with equimolar amounts of different vitamin E compounds as follows: 1) control, no supplemental vitamin E, 2) DL-alpha-tocopheryl acetate, 3) D-alpha-tocopheryl acetate, 4), D-alpha-tocopheryl succinate, 5) D-alpha-tocopheryl polyethylene glycol 1,000 succinate (TPGS), 6) DL-alpha-tocopheryl nicotinate, 7) DL-alpha-tocopheryl nicotinate+ TPGS, or 8) D-alpha-tocopheryl acetate + TPGS. During these 60 d, serum alpha-tocopherol concentrations in the control lambs remained constant and lower (P less than .05) than in lambs that received all treatments. Various indices of bioavailability, including Cmax-C(i) (concentration maximum-concentration initial), Ct-C(i) (concentration terminal-concentration initial), areas under the serum concentrations profiles, and pooled increment were higher (P less than .05) with D-alpha-tocopheryl acetate+ TPGS than in the other groups, suggesting a synergism between these forms. No such effect was observed between nicotinate and TPGS. For the TPGS, a water-soluble form of vitamin E, the indices of bioavailability were lower (P less than .05) than for the other groups. D-alpha-tocopheryl acetate resulted in a bioavailability that outranked all the other forms of vitamin E, except those of D-alpha-tocopheryl acetate + TPGS. A slightly higher bioavailability index was observed for D-alpha-tocopheryl succinate than for DL-alpha-tocopheryl nicotinate.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Bioavailability of vitamin E compounds in lambs. 150 17

For the elucidation of the mechanism of membrane stabilization by vitamin E, the effects of alpha-tocopherol and its model compounds on either retinol-induced hemolysis of rabbit erythrocytes or the permeability and fluidity of liposomal membranes have been studied. Retinol-induced rabbit erythrocyte hemolysis has been found not to be caused by the oxidative disruption of erythrocyte membrane lipids initiated by retinol oxidation, but rather to arise from physical damage of the membrane micelle induced by penetration of retinol molecules. In suppressing hemolysis, alpha-tocopherol was more effective than other naturally occurring tocopherols. alpha-Tocopheryl acetate, nicotinate, and 6-deoxy-alpha-tocopherol were more effective than alpha-tocopherol itself. The inhibitory effects of alpha-tocopherol model compounds having side chains with at least two isoprene units or a long straight chain instead of the isoprenoid side chain were similar to those of alpha-tocopherol. These data suggest that for protection of membranes against retinol-induced damage, the hydroxyl group of alpha-tocopherol is not critical, but rather the chroman ring, three methyl groups on the aromatic ring, and the long side chain are necessary. To verify the mechanism of the inhibitory effect on hemolysis, not only the effect of vitamin E and its model compounds on the membrane permeability and fluidity, but also the mobility of alpha-tocopherol molecule in membranes has been investigated using bilayer liposomes as the model membranes. Addition of alpha-tocopherol to membranes produced a greater decrease in the permeability and fluidity of rat liver phosphatidylcholine liposomes compared with egg yolk phosphatidylcholine liposomes. In dipalmitoylphosphatidylcholine liposomes, however, alpha-tocopherol was less effective, that is, the more unsaturated the lipids, the more they interact with alpha-tocopherol. 2,2,5,7,8-Pentamethyl-6-chromanol with no isoprenoid side chain and phytol without the chromanol moiety had no effect. The measurement of 13C NMR relaxation times revealed that the mobility of methyl groups on the aromatic ring of alpha-tocopherol in membranes is significantly restricted. In contrast, the methyl groups at positions 4'a and 8'a on the isoprenoid side chain have high degrees of motional freedom in the lipid core of membranes. Furthermore, it was found that alpha-tocopherol in membranes interacts with chromate ions added as potassium chromate outside the membranes, resulting in an increase in membrane fluidity. These results are compatible with those of the inhibitory effect on retinol-induced erythrocyte hemolysis. On the basis of the results obtained here, a possible mechanism for membrane stabilization by vitamin E is proposed.
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PMID:Vitamin E: inhibition of retinol-induced hemolysis and membrane-stabilizing behavior. 152 78


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