Absence Of Alpha-tocopherol Research Articles

Atheroprotective effects of pure tocotrienol supplementation in the treatment of rabbits with experimentally induced early and established atherosclerosis

BackgroundAtherosclerosis is the main cause of coronary artery disease -related deaths worldwide. The atheroprotective properties of pure tocotrienols (T3) in the absence of alpha-tocopherol (α-TCP) in vitamin E has not been extensively examined.AimTo determine the atheroprotective properties of T3 in early and established atherosclerosis rabbits.MethodsThirty New Zealand white rabbits were divided into two groups, B1 and B2 which represent early [fed 1% high cholesterol diet (HCD) for 2 weeks] and established (fed 1% HCD for 8 weeks) atherosclerosis. Each group was subdivided into three intervention arms: 1) T3–4 mg/kg, 2) T3–15 mg/kg and 3) vehicle without T3 (T3 negative) for 8 weeks. Serial fasting blood samples were obtained for lipid profile, and whole lengths of aorta were used to determine tissue markers of endothelial activation, inflammation and plaque stability.ResultsIn B1, atherosclerotic lesion in T3–4 mg/kg group was significantly reduced (p=0.008), while aortic tissue expression of vascular cellular adhesion molecule 1 (VCAM-1), interleukin-6 (IL-6) and matrix metalloproteinase (MMP-12) was reduced in T3–4 mg/kg compared to T3-negative rabbits group (0.2±0.1 vs. 28.5±3.1%; 3.0±1.6 vs. 14.0±1.7%; and 5.2±2.2 vs. 27.7±0.8%, respectively, p<0.05). T3–15 mg/kg group showed reduction in VCAM-1, E-selectin, IL-6 and MMP-12 (3.9±1.9 vs. 28.5±3.1%; 10.3±0.5 vs. 59.8±8.5%; 2.6±1.7 vs. 14.0±1.7%; and 16.2±3.2 vs. 27.7 0.8%, respectively, p<0.05). In B2, T3–4 mg/kg group reduced aortic tissue expression of intercellular adhesion molecule 1 (ICAM-1), E-selectin, IL-6, MMP-12 and MMP-9 compared to T3-negative rabbits group (29.9±2.4 vs. 55.3±1.3%; 26.7±1.5 vs. 60.5±7.6%; 15.7±0.7 vs. 27.7±4.8%; 34.8±2.7 vs. 46.5±3.4%; and 25.89±3.9 vs. 45.9±1.7%, respectively, p<0.05). T3–15 mg/kg group showed reduced VCAM-1, ICAM-1, E-selectin, IL-6, MMP-12 and MMP-9 (20.5±3.3 vs. 35.6±2.5%; 24.9±1.3 vs. 55.3±1.3%; 29.9±6.7 vs. 60.5±7.6; 11.3±2.2 vs. 27.7±4.8%; 23.0±1.7 vs. 46.5±3.4%; and 17.6±1.9 vs. 45.9±1.7%, respectively, p<0.05.ConclusionThese findings suggest the possible atheroprotective role T3 plays as an adjunct supplementation to standard treatment in the prevention of CAD.

Effect of α-tocopherol on the synthesis of phosphatidylglycerol catalyzed by phospholipase D in an aqueous system

Phosphatidylglycerol (PG) was synthesized from several phosphatidylcholines (PCs) via phospholipase D (PLD)-catalyzed transphosphatidylation in an aqueous system. The yield of PG were 71 and 68 mol% from soybean PC and egg yolk PC, respectively, under the optimum reaction conditions of 50 micromol PC, 10 mmol glycerol, 3 ml of acetate buffer, 1.6 U PLD, and 30 micromol CaCl(2) at 37 degrees C for 48 h. In case of salmon roe PC with 14.3% eicosapentaenoic acid and 26.8% docosahexaenoic acid, the PG yield increased to 94 mol% by addition of 46 mumol alpha-tocopherol, although the PG yield was only 10% in absence of alpha-tocopherol.

Unsaturated Phosphatidylethanolamine as Effective Synergist in Combination with .ALPHA.-Tocopherol

The effects of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) on the oxidation of bonito oil triacylglycerol (TAG) were examined under the absence or presence of alpha-tocopherol. Synthesized PC or PE having saturated and unsaturated fatty acids in known position were used in this study. Unsaturated PC and PE promoted TAG oxidation under the absence of alpha-tocopherol. On the contrary, unsaturated PE showed synergistic antioxidant effect with alpha-tocopherol, while PC had little effect. The strongest synergistic effect was found by 1-palmitoyl (16:0, PA)-2-docosahexaenoyl (22:6n-3)-PE, followed by 1-PA-2-arachidonyl (20:4n-6)-PE, 1,2-dioleoyl (18:1n-9)-PE, and 1-PA-2-linoleoyl (18:2n-6)-PE, respectively.

Animal experiments with ultra-high molecular weight polyethylene (UHMW-PE) stabilised with α-tocopherol used for articulating surfaces in joint endoprostheses

Numerous investigations proved the impressive suitability of alpha-tocopherol as a stabilizer for ultra-high molecular weight polyethylene (UHMW-PE) used for endoprostheses. Regarding the biocompatibility of this new biomaterial, in-vitro celltoxicity tests gave no hint for a cyto- or genotoxic activity. In this study, animal experiments are carried out to further ensure the biocompatibility of this biomaterial. Thin UHMW-PE-films (20 x 6 x 0.23 mm3) were implanted subcutaneously into rats. Morphology and reactivity of surrounding connective tissue against either pure UHMW-PE material or UHMW-PE containing alpha-tocopherol were studied at timed intervals (2 weeks, 3 month, and 6 month after operation) in 3 groups of animals, each group comprising 10 animals. Parallel to these tests, material changes were investigated in these 3 groups of 10 animals at the same intervals after operation with the help of infrared spectroscopy (FTIR). Within the implantation time, no noteworthy oxidative degradation could be observed. The amount of lost alpha-tocopherol due to diffusion is low enough to ensure a lifetime stabilisation of the UHMW-PE. The implants were all well tolerated and definitely encapsulated already 2 weeks after operation. Presence or absence of alpha-tocopherol in the implants did not evince morphological differences. Therefore, negative consequences were not manifest in the presence of alpha-tocopherol.

The role of [formula omitted]-tocopherol in plant stress tolerance

Environmental stresses trigger a wide variety of plant responses, ranging from altered gene expression to changes in cellular metabolism and growth. A plethora of plant reactions exist to circumvent the potentially harmful effects caused by light, drought, salinity, extreme temperatures, pathogen infections and other stresses. Alpha-tocopherol is the major vitamin E compound found in leaf chloroplasts, where it is located in the chloroplast envelope, thylakoid membranes and plastoglobuli. This antioxidant deactivates photosynthesis-derived reactive oxygen species (mainly 1O2 and OH), and prevents the propagation of lipid peroxidation by scavenging lipid peroxyl radicals in thylakoid membranes. Alpha-tocopherol levels change differentially in response to environmental constraints, depending on the magnitude of the stress and species-sensitivity to stress. Changes in alpha-tocopherol levels result from altered expression of pathway-related genes, degradation and recycling, and it is generally assumed that increases of alpha-tocopherol contribute to plant stress tolerance, while decreased levels favor oxidative damage. Recent studies indicate that compensatory mechanisms exist to afford adequate protection to the photosynthetic apparatus in the absence of alpha-tocopherol, and provide further evidence that it is the whole set of antioxidant defenses (ascorbate, glutathione, carotenoids, tocopherols and other isoprenoids, flavonoids and enzymatic antioxidants) rather than a single antioxidant, which helps plants to withstand environmental stress.

Ascorbic acid 2-O-alpha-glucoside-induced redox modulation in human keratinocyte cell line, SCC: mechanisms of photoprotective effect against ultraviolet light B.

We previously reported that the topical application of ascorbic acid 2-O-alpha-glucoside (AA-2G) suppressed the cutaneous inflammation by ultraviolet irradiation in human and guinea pigs (Miyai et al., Nishinihon J. Dermatol., 58, 439-443 (1996)). In this paper, the effect of AA-2G on the lethal damage induced by ultraviolet B (UVB) was studied using a human keratinocyte cell line, SCC, established from squamous cell carcinoma. The photoprotective effect of AA-2G on cytotoxicity of UVB in SCC cells was dose dependent (0.125-1 mM) and more effective than that of ascorbic acid (AsA) at 1 mM. This protection was completely abolished in the presence of an alpha-glucosidase inhibitor, castanospermine, indicating that release of AsA from this derivative was essential for reduction of the actinic injury. AA-2G significantly suppressed cytotoxicities of hydrogen peroxide and superoxide anion produced by xanthine and xanthine oxidase. AA-2G exhibited a preventive effect against the cytotoxicity produced by tert-butylhydroperoxide, an inducer of lipid peroxidation, in the presence of alpha-tocopherol, but not in the absence of alpha-tocopherol. Cytotoxicity of UVB was also effectively reduced by the combination of AA-2G and alpha-tocopherol. In addition, AA-2G reduced UVB-promoted formation of lipid peroxide and accumulation of lipofuscin, which is known to be a complex of cellular proteins and metabolites of lipid peroxide. These data suggest that AA-2G prevents the acute inflammation induced by UVB irradiation partly through scavenging reactive oxygen species and potentiating the antioxidative activity of alpha-tocopherol.

Plasma alpha-tocopherol, retinol, and carotenoids in children with falciparum malaria

Cross-sectional interactions by malaria status were investigated between plasma alpha-tocopherol, retinol, and several carotenoids (lutein, beta-cryptoxanthin, lycopene, and alpha- and beta-carotene) and indicators of disease severity (blood parasite count, hemoglobin concentration), acute-phase response (plasma albumin and ceruloplasmin concentrations), hepatic involvement (plasma alanine aminotransferase), oxidant status and antioxidant status (plasma thiobarbituric acid-reactive material and ascorbate), nutritional (weight-for-age) and carrier protein [retinol binding protein (RBP)] status, and cholesterol concentration (as a proxy for lipoprotein) in 100 consecutively admitted children with malaria. There were 50 children with severe and 50 with mild malaria and 50 age- and sex-matched control subjects. alpha-Tocopherol, retinol, and all the carotenoid concentrations were lower in the patients than in the control subjects (P < 0.001). The differences were greater in severe than in mild malaria, except for lutein. In severe malaria only, both retinol and alpha-tocopherol correlated with albumin, ceruloplasmin, and RBP concentrations whereas in all three groups retinol correlated with RBP and alpha-tocopherol correlated with cholesterol (all P < 0.01)). Using multivariate analysis on data from all patients combined, cholesterol was the most significant factor explaining the variance in alpha-tocopherol (29%) whereas RBP was responsible for 95% of the variance in retinol. Plasma cholesterol and RBP values in turn (in the absence of alpha-tocopherol and retinol, respectively) were influenced primarily by acute-phase markers (mainly albumin and ceruloplasmin). Alanine aminotransferase (r = -0.17) and thiobarbituric acid-reactive material (r = -0.17) also showed a small contribution to the variance of RBP but 60-70% remained unexplained. In conclusion, low plasma lipid-soluble micronutrient concentrations in malaria are strongly influenced by the reductions in their carrier molecules, which, in turn, are low as a consequence of the acute-phase response.

Membrane stabilizing effect of vitamin E: Existence of a hydrogen bond between .ALPHA.-tocopherol and phospholipids in bilayer liposomes.

In order to elucidate the existence of a hydrogen bond between alpha-tocopherol and phospholipids in bilayer liposomes, the effects of the presence or absence of alpha-tocopherol or its acetate on either the permeability of liposomes to chromate ions or the fluidity of liposomes composed of the different kinds of lecithin [egg yolk phosphatidylcholine (EPC), 1-oleoyl-2-palmitoylphosphatidylcholine (OPPC), or 1-O-oleyl-2-O-palmitoylphosphatidylcholine (OPPCE)] were examined. From the results obtained, it was concluded that the hydroxyl group of alpha-tocopherol is hydrogen bonded to the carbonyl group of a fatty acid ester in the phospholipids of bilayer liposomes in order to retain alpha-tocopherol molecule in the space close to the surface of membranes formed by the unsaturated fatty acid moiety of phospholipids.

Effect of nitroglycerin on size of an experimental myocardial infarct

It has been shown with reference to liver microsomes prepared in the presence and in the absence of alpha-tocopherol that structural alterations that may arise from the isolation procedure may affect interplay of carriers in NADP.H oxidation. Study of these alterations is of importance for understanding the influence of different factors of NADP.H oxidase on the involvement of NAD.H in benz(a)pyrene hydroxylation. If the electron transport via NADP.H-dependent flavoprotein is limited, the intense hydroxylation of benz(a)pyrene can be supported by means of chains involved in NAD.H oxidation. Studies have been focused on utilization of NAD.H in benz(a)pyrene hydroxylation and lipid peroxidation.