ArticlesDietary Antioxidants as Related to Vitamin E Function
Summary
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Chicks were fed a basal diet deficient in vitamin E and biologically active selenium with supplements of synthetic anti-oxidants at varying levels.
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The efficiency of the antioxidants in preventing exudative diathesis correlated with their apparent concentration in the tissues as determined by an in vitro lipid peroxidation test (thiobarbituric acid). Ethoxyquin and DPPD were most active, butylated hydroxytoluene (BHT) and ditertiary-butyl-4-methylphenol (DBPC) were intermediate, whereas nordihydroguaiaretic acid (NDGA) and 2,5-di-tertiary-amylhydroquinone (DAH) were inactive as tissue antioxidants.
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The presence of the antioxidants in liver and their effect on lipid peroxidation was confirmed by parallel studies of the iron-catalyzed oxidation of the isolated liver lipid.
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Inhibition of in vitro lipid peroxidation by dietary selenium was considerably greater than that from dietary tellurium or arsenic. These latter elements did not prevent exudates.
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A direct correlation between the α-tocopherol content of liver and the degree of in vitro lipid peroxidation was found.
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Experiments are reported which show that the slight lipid peroxidation detected in “zero time” homogenates is formed during the homogenizing procedure.
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The results indicate that the variation among antioxidants in their ability to substitute for vitamin E is due primarily to differences in their availability to the body and subsequent deposition in the tissues.
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Reprint of: Is Vitamin E the Only Lipid-Soluble, Chain-Breaking Antioxidant in Human Blood Plasma and Erythrocyte Membranes?
2022, Archives of Biochemistry and BiophysicsThe concentrations of lipid-soluble, chain-breaking antioxidants in human plasma and in erythrocyte ghosts have been determined for the first time by an inhibited autoxidation method. The results are very similar to the concentrations of vitamin E measured for the same blood components by the HPLC method. It is concluded that vitamin E, which is largely present as α-tocopherol, is the only significant lipid-soluble, chain-breaking type of antioxidant present in human blood. The concentration of vitamin E in the plasma lipids divided by the concentration of vitamin E in the ghost membrane lipids is approximately a constant despite the large differences in vitamin E-intake and in plasma lipid concentrations in different individuals. Vitamin E/lipid ratios for plasma and ghosts were larger for subjects taking a supplement of α-to- copherol acetate of 100 IU per week, compared to nonsupplemented subjects (based on data from a limited number of subjects). A larger supplement of 2800 IU per week did not significantly increase the vitamin E/lipid ratios.
Lower lipid oxidation in the muscle of rabbits fed diets containing oats
1998, Animal Feed Science and TechnologyThe susceptibility to oxidation of rabbit longissimus dorsi samples from animals receiving 300 g kg−1 oat in the feed was compared to samples from control animals receiving a diet based on barley. Dietary oat in rabbit diets balanced in digestible energy and protein did not affect feed efficiency, carcass weight and fatness. Also, intramuscular fat content was not affected by dietary treatment. Fat unsaturation, as assessed by the unsaturation index, was not modified by dietary treatment for neutral and polar lipids. After 8 days of storage thiobarbituric acid reactive substances (TBARS) of muscle samples from rabbits fed the control diet and rabbits fed the diet containing 300 g kg−1 oats were 1.32 and 0.67 mg malonaldehyde kg−1 muscle (P < 0.001), respectively. Dietary oats also reduced drip loss in longissimus dorsi muscle (P < 0.05). The presence of oat antioxidants and their possible synergistic effects suggest an interesting way of improving meat stability during storage.
The antioxidant system of the organism. Theoretical basis and practical consequences
1994, Medical HypothesesOn the basis of the literature and our own investigations, the antioxidant mechanisms and substances of the human organism are described and classified as compartmentalization, detoxification, repair and utilization. The existence and the structure of an antioxidant system, which serves as support of the antioxidant homeostasis, are hypothesized.
A parameter for characterizing the state of the antioxidant system and for detecting its changes under pathological conditions — the integral antioxidant capacity of blood plasma — and a method for its determination are suggested.
Physiological antioxidants and antioxidative enzymes in vitamin E-deficient rats
1988, Toxicology LettersThe effects of feeding vitamin E-deficient diets to rats for one year were investigated to analyse the relationship of the vitamin with other antioxidants and some antioxidative enzymes. Long-term vitamin E deficiency lowered the levels of antioxidants like vitamin E, ascorbic acid and glutathione (GSH) in all tissues analysed and thus increasing the extent of tissue peroxidisability. Vitamin E deficiency had also influenced the activities of superoxide dismutase (SOD), catalase and glutathione peroxidase, the enzymes that are involved in detoxification mechanisms of products arising from free radical metabolism.
Toxicity of nitrite and dimethylamine in rats
1983, Toxicology LettersWeanling male Wistar strain rats were administered, through the drinking water, nitrite (0.2%) and dimethylamine (DMA) (0.2%), either singly or in combination for 9 months. Some animals also received 0.5% butylated hydroxytoluene (BHT) in the diet. Nitrite, as well as DMA, caused higher in vitro lipoperoxidation, free lysosomal enzyme activities and cytosolic Superoxide dismutase activity in liver. Some of these increases viz., the enzyme activities in liver, were counteracted to a significant extent in the rats receiving a dietary supplement of BHT. The results indicate that nitrite and DMA may induce toxicity through some free radical reactions and that BHT can provide some protection.
Is vitamin E the only lipid-soluble, chain-breaking antioxidant in human blood plasma and erythrocyte membranes?
1983, Archives of Biochemistry and BiophysicsThe concentrations of lipid-soluble, chain-breaking antioxidants in human plasma and in erythrocyte ghosts have been determined for the first time by an inhibited-autoxidation method. The results are very similar to the concentrations of vitamin E measured for the same blood components by the HPLC method. It is concluded that vitamin E, which is largely present as α-tocopherol, is the only significant lipid-soluble, chain-breaking type of antioxidant present in human blood. The concentration of vitamin E-in the plasma lipids divided by the concentration of vitamin E in the ghost membrane lipids is approximately a constant despite the large differences in vitamin E-intake and in plasma lipid concentrations in different individuals. Vitamin E/lipid ratios for plasma and ghosts were larger for subjects taking a supplement of α-tocopherol acetate of 100 IU per week, compared to nonsupplemented subjects (based on data from a limited number of subjects). A larger supplement of 2800 IU per week did not significantly increase the vitamin E/lipid ratios.