Low levels of alpha tocopherol are related to a higher incidence of cardiovascular disease and increased intake appears to afford protection against cardiovascular disease. In addition to decreasing LDL oxidation, alpha tocopherol may exert intracellular effects on cells crucial in atherogenesis, such as monocytes. Hence, the aim of this study was to test the effect of alpha tocopherol supplementation on monocyte function relevant to atherogenesis. Monocyte function was assessed in 21 healthy subjects at baseline, after 8 wk of supplementation with d-alpha tocopherol (1,200 IU/d) and after a 6-wk washout phase. The release of reactive oxygen species (superoxide anion, hydrogen peroxide), lipid oxidation, release of the potentially atherogenic cytokine, interleukin 1 beta, and monocyte-endothelial adhesion were studied in the resting state and after activation of the monocytes with lipopolysaccharide at 0, 8, and 14 wk. There was a 2.5-fold increase in plasma lipid-standardized and monocyte alpha tocopherol levels in the supplemented phase. After alpha tocopherol supplementation, there were significant decreases in release of reactive oxygen species, lipid oxidation, IL-1 beta secretion, and monocyte-endothelial cell adhesion, both in resting and activated cells compared with baseline and washout phases. Studies with the protein kinase C inhibitor, Calphostin C, suggest that the inhibition of reactive oxygen species release and lipid oxidation is due to an inhibition of protein kinase C activity by alpha tocopherol. Thus, this study provides novel evidence for an intracellular effect of alpha tocopherol in monocytes that is antiatherogenic.
Background. The Free Radical Theory of Aging mechanistically links oxidative stress to aging. Okinawa has among the world's longest-lived populations but oxidative stress in this population has not been well characterized. Methods. We compared plasma lipid peroxide (LPO) and vitamin E—plasma and intracellular tocopherol levels (total α, β, and γ), in centenarians with younger controls. Results. Both LPO and vitamin E tocopherols were lower in centenarians, with the exception of intracellular β-tocopherol, which was significantly higher in centenarians versus younger controls. There were no significant differences between age groups for tocopherol: cholesterol and tocopherol: LPO ratios. Correlations were found between α-Tocopherol and LPO in septuagenarians but not in centenarians. Conclusions. The low plasma level of LPO in Okinawan centenarians, compared to younger controls, argues for protection against oxidative stress in the centenarian population and is consistent with the predictions of the Free Radical Theory of Aging. However, the present work does not strongly support a role for vitamin E in this phenomenon. The role of intracellular β-tocopherol deserves additional study. More research is needed on the contribution of oxidative stress and antioxidants to human longevity.
The oxidative metabolism of tocopherols and tocotrienols by monooxygenases is a key factor in the plasma and tissue clearance of forms of vitamin E other than α-tocopherol. It is well known that a commonly ingested form of vitamin E, γ-tocopherol, has greatly reduced plasma half life (faster clearance) than α-tocopherol. The tocotrienols are metabolized even faster than γ-tocopherol. Both γ-tocopherol and α- and δ-tocotrienol possess intriguing biological activities that are different from α-tocopherol, making them potentially of interest for therapeutic use. Unfortunately, the fast clearance of non-α-tocopherols from animal tissues is a significant hurdle to maximizing their effect(s) as dietary supplements. We report here the design and synthesis of N-heterocycle-containing analogues of α-tocopherol that act as inhibitors of Cyp4F2, the key monooxygenase responsible for ω-hydroxylation of the side chain of tocols. In particular, an ω-imidazole containing compound, 1, [(R)-2-(9-(1H-imidazol-1-yl)nonyl)-2,5,7,8-tetramethylchroman-6-ol] had an ED50 for inhibition of γ-CEHC production from γ-tocopherol of ~ 1 nM when tested in HepG2 cells in culture. Furthermore, feeding of 1 to mice along with rapidly metabolized δ-tocopherol, resulted in a doubling of the δ-tocopherol / α-tocopherol ratio in liver (P < 0.05). Thus, 1 may be a useful adjuvant to the therapeutic use of non-α-tocopherols.
tocopherol; tocotrienol; vitamin E; oxidative metabolism; CYP4F2; enzyme inhibition
Antioxidant properties of mono- and dihydroxyphenolic acids and their alkyl esters were examined, with emphasis on the relationship between their molecular structure and antioxidant activity. Test media with different tocopherol level were used for determining the oxidative stability: original refined sunflower oil (total tocopherols 149.0 mg/kg), partially tocopherol-stripped sunflower oil (total tocopherols 8.7 mg/kg) and distilled fatty acid methyl esters (FAME) as a tocopherol-free medium. The chemical reaction of tocopherols with diazomethane tested for the purpose to eliminate their antioxidant activity failed due to the negligible degree of methylation of hydroxyl group in the tocopherol molecule. Caffeic acid and protocatechuic acid (3,4-dihydroxyphenolic acids) and their alkyl esters were found to be more active antioxidants than monohydroxyphenolic acid (p-hydroxybenzoic acid), 2,5-dihydroxyphenolic acid (gentisic acid), 3-methoxy-4-hydroxyphenolic acids (vanillic and ferulic acids) and their corresponding alkyl esters. Naturally present tocopherols in refined sunflower oil proved to have a synergistic effect on gentisic acid but not on its alkyl esters. In contrast, tocopherols showed an antagonistic effect on alkyl esters of caffeic acid, because their protection factors decreased with increasing level of tocopherols in the test medium. Moreover, the antioxidant activity of these alkyl esters decreased with increasing length of their alkyl chain in conformity with the polar paradox hypothesis.
Tocopherols as naturally present antioxidants influence considerably the antioxidant activity of other antioxidants added to plant oils used as a test medium. Distilled fatty acid methyl esters prepared from refined sunflower oil may serve as an optimal tocopherol-free test medium. Some alkyl esters of phenolic acids were evaluated to be applicable as natural more lipophilic antioxidants in comparison with phenolic acids.
Alkyl esters of phenolic acids; Antioxidant activity; Lipophilic antioxidants; Phenolic acids; Tocopherols
Chronic inflammation is a risk factor for many diseases of aging. Endogenous oxidants are thought to mediate the effects of inflammation and γ-Tocopherol (γ-Toc) may mitigate damage from nitrogen-based oxidants, however, no physiological requirement for γ-Toc has been established. Regulation of tocopherols and their functional significance are poorly defined, thereby limiting their application in prevention. Using stored plasma samples from 657 male control subjects in a previous study of prostate cancer we have analyzed associations of the tocopherols, inflammation markers, and 25-OH vitamin D. Plasma α-Toc and γ-Toc were inversely correlated, whereas δ-Toc and α-Toc levels were positively correlated, suggesting a unique regulatory mechanism. γ-Toc levels were positively and α-Toc negatively associated with plasma C-reactive protein (CRP) and urinary isoprostane F2t, which are markers of inflammation and oxidation. Ethnic variability in tocopherols was observed, however, this may be explained by differences in plasma 25-OH vitamin D, as γ-Toc levels varied inversely and α-Toc positively with 25-OH vitamin D. In these data all-cause mortality appeared to be positively associated with CRP and inversely with 25-OH vitamin D. We hypothesize that plasma levels of tocopherols may serve as markers of systemic inflammation, complicating epidemiologic assessment of their role in cancer etiology.
The effect on induction period and tocopherol content after γ-irradiation on samples of olive oil and seed oils (sunflower and soybean) was determined. In seed oil samples 0, 100, 200 and 300 ppm of δ-tocopherol were added before irradiation with 1, 2 and 3kGy. The results of induction period showed that, after irradiation, all samples presented a significant decreased in resistance to oxidation. However, this decrease was minimized when δ-tocopherol was added. Irradiation significantly decreased the level of tocopherols. δ-Tocopherol appeared more sensitive in irradiation process than α- and γ-tocopherol. The addition of δ-tocopherol significantly reduced, in most cases, the depletion of the other tocopherols.
γ-irradiation; lipids; oxidation; tocopherol
The aims of the current study were to determine the half-lethal concentration of ochratoxin A (OTA) as well as the levels of lactate dehydrogenase release and DNA fragmentation induced by OTA in primary porcine fibroblasts, and to examine the role of α-tocopherol in counteracting its toxicity. Cells showed a dose-, time- and origin-dependent (ear vs. embryo) sensitivity to ochratoxin A. Pre-incubation for 3 h with 1 nM α-tocopherol significantly (P < 0.01) reduced OTA cytotoxicity, lactate dehydrogenase release and DNA damage in both fibroblast cultures. These findings indicate that α-tocopherol supplementation may counteract short-term OTA toxicity, supporting its defensive role in the cell membrane.
ochratoxin A; α-tocopherol; DNA damage; fibroblasts; swine
It has been reported that α-tocopherol (α-Toc), a vitamin E analog, is effective for treatment of non-alcoholic steatohepatitis (NASH). However, it is unknown whether or not other vitamin E analogs are effective. Therefore we designed a new rat model of steatohepatitis induced by tumor necrosis factor-α (TNF-α) stimulation, and used it to investigate the effects of vitamin E analogs. The rat liver triglyceride content increased with the dosage of TNF-α/d-galactosamine (GalN), but was suppressed by intake of both tocotrienol (T3) and α-tocopherol. Moreover, lipid peroxides (thiobarbituric acid-reactive substances) level in the liver level was also lower in both groups after tocotrienol and α-Toc intake. Intake of both tocotrienol and α-tocopherol also tended to control the increase of liver damage marker activity. In the tocotrienol and α-tocopherol groups, increases of inflammatory cytokines mRNA expression in the liver were inhibited, and these effects were considered to contribute to improvement of inflammation and fibrosis. The expression of mRNAs for inflammatory cytokines in rat primary hepatocytes was increased by TNF-α stimulation, but was inhibited by addition of α-tocotrienol and γ-tocotrienol. Transforming growth factor-β1 mRNA expression in particular was significantly inhibited by γ-tocotrienol. These findings suggest that tocotrienol species are effective for amelioration of steatohepatitis, and that tocotrienol and α-tocopherol exert a synergistic effect.
tocotrienol; tocopherol; steatohepatitis; inflammation; fibrosis
Approximately 40% of Americans take dietary supplements, including vitamin E (α-tocopherol). Unlike other fat-soluble vitamins, α-tocopherol is not accumulated to toxic levels. Rather tissue levels are tightly regulated, in part via increased hepatic metabolism and excretion that could, theoretically, alter metabolism of drugs, environmental toxins and other nutrients. To date, in vivo subcellular location(s) of α-tocopherol metabolism have not been identified. The proposed pathway of α-tocopherol metabolism proceeds via ω-hydroxylation to 13′-OH-α-tocopherol, followed by successive rounds of β-oxidation to form α-CEHC. To test the hypothesis that α-tocopherol ω-hydroxylation occurs in microsomes while β-oxidation occurs in peroxisomes, rats received daily injections of vehicle, 10 mg α-tocopherol or 10 mg trolox/100 g body wt for 3 days, then microsomes, mitochondria and peroxisomes were isolated from liver homogenates. Homogenate α-tocopherol levels increased 16-fold in α-tocopherol-injected rats, while remaining unchanged in trolox- or vehicle-injected rats. Total α-tocopherol recovered in the three subcellular fractions represented 93 ± 4% of homogenate α-tocopherol levels. In α-tocopherol-injected rats, microsome α-tocopherol levels increased 28-fold, while mitochondria and peroxisome levels increased 8- and 3-fold, respectively, indicating greater partitioning of α-tocopherol to the microsomes with increasing liver α-tocopherol. In α-tocopherol-injected rats, microsome 13′-OH-α-tocopherol levels increased 24-fold compared to controls, and were 7-fold greater than 13′-OH-α-tocopherol levels in peroxisome and mitochondrial fractions of α-tocopherol-injected rats. An unexpected finding was that α-CEHC, the end product of α-tocopherol metabolism, was found almost exclusively in mitochondria. These data are the first to indicate a mitochondrial role in α-tocopherol metabolism.
vitamin E; cytochrome P450; xenobiotic metabolism; mitochondria; peroxisome; β-oxidation; ω-oxidation; CYP
Alpha-Tocopherol and gamma-tocopherol are the two major forms of vitamin E in human plasma and the primary lipid soluble antioxidants. The dietary intake of gamma-tocopherol is generally higher than that of alpha-tocopherol. However, alpha-tocopherol plasma levels are about four fold higher than those of gamma-tocopherol. Among other factors, a preferential cellular uptake of gamma-tocopherol over alpha-tocopherol could contribute to the observed higher plasma alpha-tocopherol levels. In this investigation, we studied the uptake and depletion of both alpha-tocopherol and gamma-tocopherol (separately and together) in cultured RAW 264.7 macrophages. Similar studies were performed with alpha-tocopheryl quinone and gamma-tocopheryl quinone, which are oxidation products of tocopherols.
RAW 264.7 macrophages showed a greater uptake of gamma-tocopherol compared to alpha-tocopherol (with uptake being defined as the net difference between tocopherol transported into the cells and loss due to catabolism and/or in vitro oxidation). Surprisingly, we also found that the presence of gamma-tocopherol promoted the cellular uptake of alpha-tocopherol. Mass balance considerations suggest that products other than quinone were formed during the incubation of tocopherols with macrophages.
Our data suggests that gamma-tocopherol could play a significant role in modulating intracellular antioxidant defence mechanisms. Moreover, we found the presence of gamma-tocopherol dramatically influenced the cellular accumulation of alpha-tocopherol, i.e., gamma-tocopherol promoted the accumulation of alpha-tocopherol. If these results could be extrapolated to in vivo conditions they suggest that gamma-tocopherol is selectively taken up by cells and removed from plasma more rapidly than alpha-tocopherol. This could, in part, contribute to the selective maintenance of alpha-tocopherol in plasma compared to gamma-tocopherol.
Effects of α-, β-, γ- and δ-tocopherols on the proliferation and invasion of AH109A hepatoma cells and their modes of action were investigated. Four tocopherols inhibited the invasion as well as the proliferation of AH109A cells. Their inhibitory effects were more prominent on the invasion than on the proliferation. At 1 µM, α-tocopherol showed most potent anti-invasive activity without any influence on the proliferation. We have previously demonstrated that reactive oxygen species increase the invasion of AH109A cells. α-Tocopherol suppressed the reactive oxygen species-induced invasion but failed to suppress the reactive oxygen species-induced rises in intracellular peroxide level. GF 109203X, a protein kinase C inhibitor, decreased the invasive activity of AH109A cells. In contrast, phorbol-12-myristate-13-acetate, a protein kinase C activator, increased the invasive capacity of AH109A cells. α-Tocopherol suppressed the phorbol-12-myristate-13-acetate-induced increase in the invasion, and canceled the phorbol-12-myristate-13-acetate-induced rises in protein kinase C activity and phosphorylation of extracellular signal-regulated kinase. These results suggest that tocopherols, especially α-tocopherol, possess inhibitory effect more strongly on the invasion of AH109A cells than on the proliferation. They also suggest that the anti-invasive activity of α-tocopherol is raised through suppression of PKC/ERK signaling.
tocopherol; hepatoma; invasion; protein kinase C; reactive oxygen species
An oxidized frying oil (OFO) diet has been reported to induce an increase in lipid peroxidation and a reduction in vitamin E status in animal tissues. This study was performed to investigate how vitamin E metabolism is influenced by OFO. Male Wistar rats were divided into three groups, a control group (CO) and two OFO-fed groups (OF and OFE). The diet of the OFE group was supplemented with an extra 50 mg/kg of α-tocopherol acetate and thus contained twice as much vitamin E as that of the OF group. After six weeks on these diets, liver α-tocopherol levels in the OF group were the significantly lowest among the three groups. Excretion of the α-tocopherol metabolite, α-carboxyethyl hydroxychroman (α-CEHC) in the urine was significantly lower in the OF group than in the other two groups. There were no significant differences in protein levels of α-tocopherol transfer protein (α-TTP) and multidrug resistance protein among the three groups. Protein levels of cytochrome P450 monooxygenase (CYP) 3A, CYP4A, and catalase were markedly increased in both groups on the OFO diet. This suggests that an OFO diet may interfere with medicine metabolism and needs further investigation.
oxidized frying oil; α-tocopherol; α-carboxyethyl hydroxychroman; cytochrome P450; rats
Lipopolysaccharide (LPS) induces host inflammatory responses and tissue injury and has been implicated in the pathogenesis of various age-related diseases such as acute respiratory distress syndrome, vascular diseases, and periodontal disease. Antioxidants, particularly vitamin E, have been shown to suppress oxidative stress induced by LPS, but the previous studies with different vitamin E isoforms gave inconsistent results. In the present study, the protective effects of α- and γ-tocopherols and α- and γ-tocotrienols on the oxidative stress induced by LPS against human lung carcinoma A549 cells were studied. They suppressed intracellular reactive oxygen formation, lipid peroxidation, induction of inflammatory mediator cytokines, and cell death. Tocopherols were incorporated into cultured cells much slower than tocotrienols but could suppress LPS-induced oxidative stress at much lower intracellular concentration than tocotrienols. Considering the bioavailability, it was concluded that α-tocopherol may exhibit the highest protective capacity among the vitamin E isoforms against LPS-induced oxidative stress.
► Lipopolysaccharide (LPS) induces oxidative stress in cultured cells. ► Protective effect of four vitamin E isoforms against LPS cytotoxicity was studied. ► α- and γ-tocopherols and tocotrienols suppressed oxidative damage and cell death. ► Tocotorienols were incorporated into cells much faster than tocopherols. ► α-Tocopherol may exert the highest capacity to inhibit LPS-induced cytotoxicity.
DCFH, Dichlorofluorescein; DPPP, Diphenyl-1-pyrenylphosphine; LPS, Lipopolysaccharide; MTT, 3-[4,5-dimethylthiazol-2-yl]2,5-dipheyltetrazolium bromide; NF-κB, Nuclear factor-kappaB; ROS, Reactive oxygen species; SP-D, Pulmonary surfactant protein D; Toc, Tocopherol; Toc3, Tocotrienol; TNF-α, Tumor necrosis factor α; Lipid peroxidation; Lipopolysaccharide (LPS); Oxidative stress; Tocopherol; Tocotrienol; Vitamin E
Rapeseed (Brassica napus L.) is the most important oil crop of temperate climates. Rapeseed oil contains tocopherols, also known as vitamin E, which is an indispensable nutrient for humans and animals due to its antioxidant and radical scavenging abilities. Moreover, tocopherols are also important for the oxidative stability of vegetable oils. Therefore, seed oil with increased tocopherol content or altered tocopherol composition is a target for breeding. We investigated the role of nucleotide variations within candidate genes from the tocopherol biosynthesis pathway. Field trials were carried out with 229 accessions from a worldwide B. napus collection which was divided into two panels of 96 and 133 accessions. Seed tocopherol content and composition were measured by HPLC. High heritabilities were found for both traits, ranging from 0.62 to 0.94. We identified polymorphisms by sequencing selected regions of the tocopherol genes from the 96 accession panel. Subsequently, we determined the population structure (Q) and relative kinship (K) as detected by genotyping with genome-wide distributed SSR markers. Association studies were performed using two models, the structure-based GLM + Q and the PK-mixed model. Between 26 and 12 polymorphisms within two genes (BnaX.VTE3.a, BnaA.PDS1.c) were significantly associated with tocopherol traits. The SNPs explained up to 16.93% of the genetic variance for tocopherol composition and up to 10.48% for total tocopherol content. Based on the sequence information we designed CAPS markers for genotyping the 133 accessions from the second panel. Significant associations with various tocopherol traits confirmed the results from the first experiment. We demonstrate that the polymorphisms within the tocopherol genes clearly impact tocopherol content and composition in B. napus seeds. We suggest that these nucleotide variations may be used as selectable markers for breeding rapeseed with enhanced tocopherol quality.
Brassica napus; tocopherol (vitamin E); candidate genes; association study; SNP identification
Oxidative stress and inflammation are crucial in atherogenesis. α-Tocopherol is both an antioxidant and an antiinflammatory agent.
We evaluated the effect of RRR-α-tocopherol supplementation on carotid atherosclerosis in patients with stable coronary artery disease (CAD) on drug therapy.
Randomized, controlled, double-blind trial compared RRR-α-tocopherol (1200 IU/d for 2 y) with placebo in 90 patients with CAD. Intimal medial thickness (IMT) of both carotid arteries was measured by high-resolution B-mode ultrasonography at 0, 1, 1.5, and 2 y. At 6-mo intervals, plasma α-tocopherol concentrations, C-reactive protein (CRP), LDL oxidation, monocyte function (superoxide anion release, cytokine release, and adhesion to endothelium), and urinary F2-isoprostanes were measured.
α-Tocopherol concentrations were significantly higher in the α-tocopherol group but not in the placebo group. High-sensitivity CRP concentrations were significantly lowered with α-tocopherol supplementation than with placebo (32%; P <0.001). α-Tocopherol supplementation significantly reduced urinary F2-isoprostanes (P <0.001) and monocyte superoxide anion and tumor necrosis factor release compared with baseline and placebo (P < 0.001). No significant difference was observed in the mean change in total carotid IMT in the placebo and α-tocopherol groups. In addition, no significant difference in cardiovascular events was observed (P = 0.21).
High-dose RRR-α-tocopherol supplementation in patients with CAD was safe and significantly reduced plasma biomarkers of oxidative stress and inflammation but had no significant effect on carotid IMT during 2 y.
Vitamin E; atherosclerosis; coronary artery disease; inflammation; oxidative stress; intimal media thickness; carotid
Vitamin E (α-tocopherol) is a major lipid-soluble chain-breaking antioxidant in humans and mammals and plays an important role in normal development and physiology. The localization of α-tocopherol within the highly unsaturated phospholipid bilayer of cell membranes provides a means of controlling lipid oxidation at the initiation site. Mitochondria are the site for major oxidative processes and are important in fat oxidation and energy production, but a side effect is leakage of reactive oxygen species. Thus, incorporation of α-tocopherol and other antioxidants into mitochondria and other cellular compartments is important in order to maintain oxidative stability of the membrane-bound lipids and prevent damage from the reactive oxygen species. Many studies regarding mitochondrial disease and dysfunction have been performed in relation to deficiency of vitamin E and other antioxidants, whereas relatively sparse information is available regarding the eventual beneficial effects of antioxidant-enriched mitochondria in terms of health and function. This may be due to the fact that only little scientific information is available concerning the effect of supranutritional supplementation with antioxidants on their incorporation into mitochondria and other cellular membranes. The purpose of this review is therefore to briefly summarize experimental data performed with dietary vitamin E treatments in relation to the deposition of α-tocopherol in mitochondria and microsomes.
Vitamin C; Immune cells; Antioxidants; Oxidative stress; Lipid oxidation
Stimulated human phagocytes produce sister chromatid exchanges in cultured mammalian cells by a mechanism involving oxygen metabolites. Experiments were designed to determine whether antioxidants inhibit this process. Superoxide dismutase, catalase, and hydroxyl radical scavengers (benzoate, mannitol) protected target Chinese hamster ovary cells from phagocyte-induced sister chromatid exchanges, implicating the involvement of hydroxyl radicals in this chromosomal damage. N-acetylcysteine and beta-carotene were also protective. alpha-Tocopherol (greater than 5 microM) protected target cells exposed to phagocytes but not to enzymatically generated oxidants when the vitamin was added just before the source of oxygen radicals, suggesting, as reported by others, that the principal action of tocopherol in this setting was to inhibit the release of oxidants from phagocytes. On the other hand, cultivation of target cells with supplemental tocopherol protected them from the toxic effects of the enzymatic oxidant-producing system, indicating a role for membrane-associated free radicals in the mechanism of sister chromatid exchange induction. Low concentrations of sodium selenite (0.1-1.0 microM) protected the target cells. However, higher concentrations (10 microM) of selenite had no effect on oxidant-induced sister chromatid exchange formation, and 0.1 mM selenite increased the number of exchanges. Sodium selenite concentrations of 0.1 mM also decreased the intracellular glutathione concentration of target cells during an oxidant stress, and reducing target cell glutathione concentrations with buthionine sulfoximine increased their sensitivity to oxygen-related chromosomal damage. Therefore, the potentiation of oxygen radical-induced chromosomal damage observed with high concentrations of selenite may result from a decrease in the thiol antioxidant defense systems within the cell. The findings suggest that the hydroxyl radical has an important role in the production of phagocyte-induced cytogenetic injury, membrane-derived intermediates may be involved, depletion of intracellular glutathione renders cells more susceptible to this injury, and supplementation of target cells with antioxidants can protect them from oxygen radical-generated chromosomal injury.
A disturbance in the antioxidant defense system including α-tocopherol, ascorbic acid and reduced glutahtione metabolism due to free radical induced oxidative injury has been implicated in various neuro-psychiatric disorders. The roles of these antioxidants, changes in their blood levels and correlation with oxidative stress were studied in a common psychiatric illness Schizophrenia. Fifty-eight subjects of either sex ranging in age from 18–60 years divided into two age groups (≤40 and >40 years) diagnosed for schizophrenia, and forty age and sex-matched normal subjects as controls were included in the study. Blood samples were analyzed for malondialdehyde (MDA), α-tocopherol, total ascorbic acid (TAA), dehydro ascorbic acid (DHAA), reduced ascorbic acid (RAA), leucocyte ascorbic acid (LAA) and reduced glutathione (GSH). A decrease in the levels of α-tocopherol, total ascorbic acid and reduced glutathione was found in schizophrenics compared to normal controls. Further a significant rise in oxidative stress and decreased antioxidant status was observed in the chronic stage of schizophrenia as compared to those in acute condition. A significant rise in dehydroascorbic acid with concomitant fall in reduced ascorbic acid suggests scavenging action of ascorbic acid and its utilization with increased oxidative stress as indicated by high blood malondialdehyde levels. Leucocyte ascorbic acid, a better index of ascorbic acid status was also found to be reduced in schizophrenics, suggesting depletion of body stores of ascorbic acid and the condition worsened with advancing age.
Oxidative stress; Malondialdehyde; α-tocopherol; Ascorbic acid; Dehydroascorbic acid; Glutathione; Schizophrenia
We have reported that supplemental doses of the α- and γ-tocopherol isoforms of vitamin E decrease and increase, respectively, allergic lung inflammation. We have now assessed whether these effects of tocopherols are reversible. For these studies, mice were treated with antigen and supplemental tocopherols in a first phase of treatment followed by a 4 week clearance phase and then the mice received a second phase of antigen and tocopherol treatments. The pro-inflammatory effects of supplemental levels of γ-tocopherol in phase 1 were only partially reversed by supplemental α-tocopherol in phase 2 but were completely reversed by raising α-tocopherol levels 10-fold in phase 2. When γ-tocopherol levels were increased 10-fold (highly-elevated tocopherol) so that the lung tissue γ-tocopherol levels were equal to the lung tissue levels of supplemental α-tocopherol, γ-tocopherol reduced leukocyte numbers in the lung lavage fluid. In contrast to the lung lavage fluid, highly-elevated levels of γ-tocopherol increased inflammation in the lung tissue. These regulatory effects of highly-elevated tocopherols on tissue inflammation and lung lavage fluid were reversible in a second phase of antigen challenge without tocopherols. In summary, the pro-inflammatory effects of supplemental γ-tocopherol on lung inflammation were partially reversed by supplemental levels of α-tocopherol but were completely reversed by highly-elevated-levels of α-tocopherol. Also, highly-elevated levels of γ-tocopherol were inhibitory and reversible in lung lavage but, importantly, were pro-inflammatory in lung tissue sections. These results have implications for future studies with tocopherols and provide a new context in which to review vitamin E studies in the literature.
inflammation; tocopherol; vitamin E; endothelial cell; leukocyte recruitment
Crystal aggregation and retention are critical events for the formation of kidney stones. There is a close association between crystal development and free radical activity in vivo. In the present study 30 subjects presenting with urolithiasis were included. Serum levels of total lipid peroxides, nitric oxide (as nitrite), α-tocopherol, plasma ascorbic acid (vitamin C) and erythrocyte superoxide dismutase activity were measured. These findings were compared with 30 age matched control subjects irrespective of sex. Student's ‘t’ test was applied for statistical analysis. There was a significant increase in lipid peroxides (p<0.001), where as significant decrease in nitrite (p<0.01) and α-tocopherol (p<0.001) levels were observed. Plasma ascorbate (p>0.05) and erythrocyte superoxide dismutase activity (p>0.05) was also found to be decreased but the difference was not statistically significant which suggests that oxidative stress is evident in urolithiasis with depletion in antioxidant status where as decrease in nitric oxide may be less abetting in disease condition.
Urolithiasis; Lipid Peroxidation; Nitric Oxide; Antioxidants
We sought to investigate the relationships among the plasma levels of carotenoids, tocopherols, endogenous antioxidants, oxidative damage and lipid profiles and their possible effects on the cardiovascular risk associated with hemodialysis (HD) patients.
The study groups were divided into HD and healthy subjects. Plasma carotenoid, tocopherol and malondialdehyde (MDA) levels, as well as erythrocyte reduced glutathione (GSH), were measured by HPLC. Blood antioxidant enzymes, kidney function biomarkers and the lipid profiles were analyzed by spectrophotometric methods.
Plasma lycopene levels and blood glutathione peroxidase (GPx) activity were significantly decreased in HD patients compared with healthy subjects. Total cholesterol, low-density lipoprotein cholesterol (LDL-c), creatinine, urea, MDA, GSH, superoxide dismutase (SOD) and catalase (CAT) were significantly increased in HD (p < 0.05). Lycopene levels were correlated with MDA (r = -0.50; p < 0.01), LDL-c (r = -0.38; p = 0.01) levels, the LDL-c/HDL-c index (r = -0.33; p = 0.03) and GPx activity (r = 0.30; p = 0.03). Regression models showed that lycopene levels were correlated with LDL-c (β estimated = -31.59; p = 0.04), while gender was correlated with the TC/HDL-c index and triglycerides. Age did not present a correlation with the parameters evaluated. GPx activity was negatively correlated with MDA levels and with the LDL-c/HDL-c and CT/HDL-c indexes.
Lycopene may represent an additional factor that contributes to reduced lipid peroxidation and atherogenesis in hemodialysis patients.
The elevated level of circulating estradiol increases the risk of breast tumor development. To gain further insight into mechanisms involved in their actions, we investigated the molecular mechanisms of 4-hydroxyestradiol (4-OHE2) to initiate and/or promote abnormal cell growth, and of α- or γ-tocopherol to inhibit this process. MCF-10A, human breast epithelial cells were incubated with 0.1 µM 4-OHE2, either with or without 30 µM tocopherols for 96 h. 4-OHE2 caused the accumulation of intracellular ROS, while cellular GSH/GSSG ratio and MnSOD protein levels were decreased, indicating that there was an oxidative burden. 4-OHE2 treatment also changed the levels of DNA repair proteins, BRCA1 and PARP-1. γ-Tocopherol suppressed the 4-OHE2-induced increases in ROS, GSH/GSSG ratio, and MnSOD protein expression, while α-tocopherol up-regulated BRCA1 and PARP-1 protein expression. In conclusion, 4-OHE2 increases oxidative stress reducing the level of proteins related to DNA repair. Tocopherols suppressed oxidative stress by scavenging ROS or up-regulating DNA repair elements.
Breast cancer; DNA damage; 4-hydroxyestradiol; oxidative stress; tocopherol
To determine the effects of α-tocopherol supplementation to oocyte maturation media and embryo culture media on the yield of ovine embryos.
α-tocopherol, at concentrations of 0, 50, 100, 200, 400 and 500 µM was supplemented to ovine oocyte or embryo culture media and cultured at 5% or 20% O2 levels. Percentages of cleavage, morula and blastocyst, total cell count and comet assay were taken as indicators of developmental competence of embryos.
200 µM α-tocopherol in embryo culture medium at 20% O2 level significantly increased the rates of cleavage (P < 0.05), morulae (P < 0.05) and blastocyst (P < 0.01) formation and blastocyst total cell number (P < 0.01) when compared with control. The rates of blastocyst formation were also significantly higher in 100 µM (P < 0.01) and 400 µM (P < 0.05) supplemented groups than control.
α-tocopherol supplementation may enhance the in vitro developmental competence of ovine embryos by protecting them from oxidative damage.
Vitamin E; Ovine; In vitro fertilization; Oxidative stress; Embryo culture
To investigate the global effects of vitamin E supplementation on aging, we used high-density oligonucleotide arrays to measure transcriptional alterations in the heart and brain (neocortex) of 30-month-old B6C3F1 mice supplemented with α- and γ-tocopherol since middle age (15 months). Gene expression profiles were obtained from 5- and 30-month-old controls and 30-month-old mice supplemented with α-tocopherol (1g/kg), or a mixture of α- and γ-tocopherol (500mg/kg of each tocopherol). In the heart, both tocopherol supplemented diets were effective in inhibiting the expression of genes previously associated with cardiomyocyte hypertrophy and increased innate immunity, while having a moderate effect on age-related transcriptional alterations linked to the stress response and protein synthesis. In the brain, induction of genes encoding ribosomal proteins and proteins involved in ATP biosynthesis was observed with aging and was markedly prevented by the mixture of α- and γ-tocopherol supplementation, but not by α-tocopherol alone. These results demonstrate that middle age-onset dietary supplementation with α- and γ-tocopherol can partially prevent age-associated transcriptional changes and that these effects are tissue- and tocopherol-specific.
vitamin E; aging; microarray; heart; brain
Tocopherols are natural antioxidants with both in vivo (vitamin E) and in vitro activity. Sunflower seeds contain predominantly alpha-tocopherol (>90% of total tocopherols), with maximum vitamin E effect but lower in vitro antioxidant action than other tocopherol forms such as gamma-tocopherol. Sunflower germplasm with stable high levels of gamma-tocopherol (>85%) has been developed. The trait is controlled by recessive alleles at a single locus Tph2 underlying a gamma-tocopherol methyltransferase (gamma-TMT). Additionally, unstable expression of increased gamma-tocopherol content in the range from 5 to 85% has been reported. The objective of this research was to determine the genetic basis of unstable expression of high gamma-tocopherol content in sunflower seeds.
Male sterile plants of nuclear male sterile line nmsT2100, with stable high gamma-tocopherol content, were crossed with plants of line IAST-1, with stable high gamma-tocopherol content but derived from a population that exhibited unstable expression of the trait. F2 seeds showed continuous segregation for gamma-tocopherol content from 1.0 to 99.7%. Gamma-tocopherol content in F2 plants (average of 24 individual F3 seeds) segregated from 59.4 to 99.4%. A genetic linkage map comprising 17 linkage groups (LGs) was constructed from this population using 109 SSR and 20 INDEL marker loci, including INDEL markers for tocopherol biosynthesis genes. QTL analysis revealed a major QTL on LG 8 that corresponded to the gamma-TMT Tph2 locus, which suggested that high gamma-tocopherol lines nmsT2100 and IAST-1 possess different alleles at this locus. Modifying genes were identified at LGs 1, 9, 14 and 16, corresponding in most cases with gamma-TMT duplicated loci.
Unstable expression of high gamma-tocopherol content is produced by the effect of modifying genes on tph2a allele at the gamma-TMT Tph2 gene. This allele is present in line IAST-1 and is different to allele tph2 present in line nmsT2100, which is not affected by modifying genes. No sequence differences at the gamma-TMT gene were found associated to allelic unstability. Our results suggested that modifying genes are mostly epistatically interacting gamma-TMT duplicated loci.