Search results for "OXIDATION"
showing 10 items of 1913 documents
Supplementation with cactus pear (Opuntia ficus-indica) fruit decreases oxidative stress in healthy humans: a comparative study with vitamin C.
2004
Background: Cactus pear (Opuntia ficus-indica) fruit contains vitamin C and characteristic betalain pigments, the radical-scavenging properties and antioxidant activities of which have been shown in vitro. Objective: We investigated the effects of short-term supplementation with cactus pear fruit compared with vitamin C alone on total-body oxidative status in healthy humans. Design: In a randomized, crossover, double-treatment study, 18 healthy volunteers received either 250 g fresh fruit pulp or 75 mg vitamin C twice daily for 2 wk, with a 6-wk washout period between the treatments. Before (baseline) and after each treatment, 8-epiprostaglandin F2α (8-epi-PGF2α) and malondialdehyde in plas…
Contribution of vitamin A to the oxidation resistance of human low density lipoproteins.
1995
This study investigated the antioxidant contribution of vitamin A in protecting human low density lipoprotein (LDL) against copper-stimulated oxidation. The presence of small amounts of retinol (0.033 ± 0.012 nmol/mol LDL) and retinyl palmitate (0.036 ± 0.021 nmol/mol LDL) was routinely ascertained in the LDL. A single oral supplementation with 20,000 IU vitamin A caused a two- to three-fold increase of retinol and retinyl palmitate in the LDL isolated 8 h after the supplementation. In comparison to autologous-control LDL, vitamin A-enriched LDL were more resistant to oxidation, as expressed both by a clear delay in the onset of lipid peroxidation and by a reduction of the rate of conjugate…
Oral administration of vitamin C decreases muscle mitochondrial biogenesis and hampers training-induced adaptations in endurance performance
2008
Background Exercise practitioners often take vitamin C supplements because intense muscular contractile activity can result in oxidative stress, as indicated by altered muscle and blood glutathione concentrations and increases in protein, DNA, and lipid peroxidation. There is, however, considerable debate regarding the beneficial health effects of vitamin C supplementation. Objective This study was designed to study the effect of vitamin C on training efficiency in rats and in humans. Design The human study was double-blind and randomized. Fourteen men (27-36 y old) were trained for 8 wk. Five of the men were supplemented daily with an oral dose of 1 g vitamin C. In the animal study, 24 mal…
Antioxidant status and circulating lipids are altered in human gestational diabetes and macrosomia.
2007
Fetuses from mothers with gestational diabetes are at increased risk of developing neonatal macrosomia and oxidative stress. We investigated the modulation of antioxidant status and circulating lipids in gestational diabetic mothers and their macrosomic babies and in healthy age-matched pregnant women and their newborns. The serum antioxidant status was assessed by employing anti-radical resistance kit (KRL; Kirial International SA, Couternon, France) and determining levels of vitamin A, C, and E and the activity of superoxide dismutase (SOD). Circulating serum lipids were quantified, and lipid peroxidation was measured as the concentrations of serum thiobarbituric acid-reactive substances …
FIA-fluorimetric determination of thiamine.
1990
A flow injection-fluorimetric determination of thiamine is reported. The procedure is based on the oxidation of the analyte with potassium hexacyanoferrate(III) immobilized on an anionic exchange resin; the fluorescence is monitored in aqueous basic solution. Concentrations of the vitamin of 0.1-4 ppm have been determined; the relative standard deviation was 1.8%. The injection rate was 28 samples/h. The influence of other substances and the determination of the drug in a pharmaceutical formulation are also reported.
[37] Interactions between vitamin A and vitamin E in liposomes and in biological contexts
1999
Publisher Summary This chapter discusses the interactions between vitamin A and vitamin E in liposomes. The chapter reviews several studies carried out by incorporating a variable proportion of all- trans -retinol and α-tocopherol in soybean phosphatidylcholine liposomes. It discusses the antioxidant effectiveness of all- trans - retinol in retinal membranes, whether deprived of endogenous α-tocopherol. In the experiments discussed in the chapter, synergistic effects between all- trans -retinal and α -tocopherol are evident in chemical bilayer as well as in natural membranes. In addition, when all- trans -retinol and α –tocopherol are allowed to act in combination, consumption of both antio…
Antioxidant Activity of Vitamin A within Lipid Environments
1998
New information about deleterious effects of free radicals on cell compartments, and a growing amount of associations between free radicals and various pathological conditions, have produced considerable interest in the biological defense systems against oxidative injury. The antioxidant properties of vitamin A, known for decades (Monaghan and Schmitt, 1932), have been reinvestigated in recent years in chemical as well as in biological systems. Its lipid nature and the localization within the lipophilic compartment of membranes and lipoproteins make vitamin A effective in reducing lipid peroxidation by acting as a chain-breaking antioxidant.
Synergistic Interactions between Vitamin A and Vitamin E against Lipid Peroxidation in Phosphatidylcholine Liposomes
1996
Interactions between alpha-tocopherol and all-trans retinol in suppressing lipid peroxidation were studied in a unilamellar liposomal system of phosphatidylcholine from either egg or soybean, in which peroxidation was initiated by the water-soluble azo initiator 2,2-azobis(2-amidino-propane)hydrochloride and peroxidation was measured as production of conjugated diene hydroperoxides. While all-trans retinol alone was poorly effective, the combination of all-trans retinol with alpha-tocopherol caused an inhibition period far beyond the sum of the inhibition periods observed with individual antioxidants, providing evidence of synergistic interactions. Furthermore, the inhibition rate calculate…
A Comprehensive Review on Lipid Oxidation in Meat and Meat Products.
2019
Meat and meat products are a fundamental part of the human diet. The protein and vitamin content, as well as essential fatty acids, gives them an appropriate composition to complete the nutritional requirements. However, meat constituents are susceptible to degradation processes. Among them, the most important, after microbial deterioration, are oxidative processes, which affect lipids, pigments, proteins and vitamins. During these reactions a sensory degradation of the product occurs, causing consumer rejection. In addition, there is a nutritional loss that leads to the formation of toxic substances, so the control of oxidative processes is of vital importance for the meat industry. Noneth…
Effect of corn oil and vitamin E on the oxidative status of adipose tissues and liver in rat
2003
Abstract The diet is usually formed of a varying antioxidant and fatty acid content acquired from oils. The purpose of this study was to determine the effects of corn oil-rich diet supplemented or not with vitamin E on oxidative damage and antioxidant status in liver and adipose tissue of rat. Male Wistar rats were fed during 4 weeks with a hyperlipidic diet. The groups fed with hyperlipidic diets showed lower activity levels than the control groups with the exception of superoxide dismutase and glutathione peroxidase in brown adipose tissue. Supplementation of the control group with vitamin E (CE) did not produce any significant changes in the superoxide dismutase and catalase levels, but …