The role of alpha-tocopherol in preventing disease: from epidemiology to molecular events

Dietary vitamin C and vitamin E with the risk of aortic aneurysm and dissection: A prospective population-based cohort study

BACKGROUND AND AIMS

The associations between dietary vitamin C (VC), vitamin E (VE) intake and aortic aneurysm and dissection (AAD) remain unclear. This study aimed to prospectively investigate the associations between dietary VC and VE with the incident risk of AAD.

METHODS AND RESULTS

A total of 139 477 participants of UK Biobank cohort were included in the analysis. Dietary VC and VE consumptions were acquired through a 24-h recall questionnaire. Cox proportional regression models were used to examine the associations between VC, VE intake and the risk of AAD. Incident AAD was ascertained through hospital inpatient records and death registers. During a median follow-up of 12.5 years, 962 incident AAD events were documented. Both dietary VC [adjusted hazard ratio (HR), 0.77; 95 % confidence intervals (CI), 0.63-0.93; P-trend = 0.008] and VE (adjusted HR, 0.70; 95 % CI, 0.57-0.87; P-trend = 0.002) were inversely associated with incident AAD when comparing the participants in the highest quartile with those in the lowest. In subgroup analyses, the associations were more pronounced in participants who were over 60 years old, participants with smoking history, hypertension or hyperlipidemia, who were under the high risk of AAD.

CONCLUSION

Higher dietary VC and VE intakes are associated with reduced risk of AAD. Our study emphasizes the importance of diet adjustment strategies targeted on VC and VE to lower the incidence rate of AAD especially in the high-risk population.

Protective Actions of α-Tocopherol on Cell Membrane Lipids of Paraquat-Stressed Human Astrocytes Using Microarray Technology, MALDI-MS and Lipidomic Analysis

Cellular senescence is one of the main contributors to some neurodegenerative disorders. The early detection of senescent cells or their related effects is a key aspect in treating disease progression. In this functional deterioration, oxidative stress and lipid peroxidation play an important role. Endogenous antioxidant compounds, such as α-tocopherol (vitamin E), can mitigate these undesirable effects, particularly lipid peroxidation, by blocking the reaction between free radicals and unsaturated fatty acid. While the antioxidant actions of α-tocopherol have been studied in various systems, monitoring the specific effects on cell membrane lipids at scales compatible with large screenings has not yet been accomplished. Understanding the changes responsible for this protection against one of the consequences of senescence is therefore necessary. Thus, the goal of this study was to determinate the changes in the lipid environment of a Paraquat-treated human astrocytic cell line, as a cellular oxidative stress model, and the specific actions of the antioxidant, α-tocopherol, using cell membrane microarray technology, MALDI-MS and lipidomic analysis. The stress induced by Paraquat exposure significantly decreased cell viability and triggered membrane lipid changes, such as an increase in certain species of ceramides that are lipid mediators of apoptotic pathways. The pre-treatment of cells with α-tocopherol mitigated these effects, enhancing cell viability and modulating the lipid profile in Paraquat-treated astrocytes. These results demonstrate the lipid modulation effects of α-tocopherol against Paraquat-promoted oxidative stress and validate a novel analytical high-throughput method combining cell cultures, microarray technology, MALDI-MS and multivariate analysis to study antioxidant compounds against cellular senescence.

Liquid chromatography as candidate reference method for the determination of vitamins A and E in human serum

BACKGROUND

Owing to the increasing interest in public health research of antioxidant micronutrients and the inaccuracy of routine serum concentrations of the fat-soluble vitamins A (retinol) and E (DL-α-tocopherol) measurements, we developed a reliable, highly sensitive, robust and rapid method for the quantification of two clinically important lipophilic antioxidants in serum using a reverse-phase HPLC/DAD method.

METHOD

Sample preparation and analytical conditions that would affect extraction efficiency and quantitative results of vitamins A and E were investigated and optimized. Vitamins A and E were extracted from serum via liquid-liquid extraction (LLE). After adequate sample preparation, the samples were injected directly into the HPLC system with diode-array detector (DAD). Chromatographic separation was completed in 7 minutes for vitamins A and E. With vitamin A acetate and vitamin E acetate as internal standards, the method was applied to the measurement of vitamins A and E in human serum.

RESULTS

We evaluated method linearity, accuracy (recovery rate and trueness), precision, carryover, limit of quantitation and limit of detection, and measurement uncertainty. The method was evaluated for trueness using NIST Standard Reference Material SRM 968f. The serum concentration of the studied compounds had a good linear relationship in the range of 0.05 ~ 3.0 μg/mL concentration (r ＝ 0.9998), with 0.0077 μg/mL detection limit and 0.025 μg/mL quantitative limit for vitamin A, respectively, and 1.0 ~ 60.0 μg/mL concentration (r ＝ 0.9999), with 0.40 μg/mL detection limit and 0.50 μg/mL quantitative limit for vitamin E, respectively. The intra- and inter-assay coefficients of variation were calculated by using three concentrations (1, 2, and 3) of the studied compounds in human serum samples. Intra-assay and inter-assay precision were 1.23%-4.97% and 0.97%-3.79% for vitamin A, respectively, and 0.64%-4.07% and 0.81%-5.96% for vitamin E, respectively. The average recovery rates were 100.98% for vitamin A, and 99.21% for vitamin E, respectively. The carryover rate of vitamins A and E was below 1%. As for the evaluation of accuracy, the biases were <± 5% by comparing with NIST standard reference material SRM 968f.

CONCLUSION

The method is a simple sample treatment procedure for the determination of fat-soluble vitamins A and E in human serum with high sensitivity and specificity. The proposed method could be recommended as a candidate reference method for the determination of serum concentrations of the fat-soluble vitamins A and E in human serum.

Alpha-tocopherol inhibits pore formation in oxidized bilayers

In biological membranes, alpha-tocopherols (α-toc; vitamin E) protect polyunsaturated lipids from free radicals. Although the interactions of α-toc with non-oxidized lipid bilayers have been studied, their effects on oxidized bilayers remain unknown. In this study, atomistic molecular dynamics (MD) simulations of oxidized lipid bilayers were performed with varying concentrations of α-toc. Bilayers with 1-palmitoyl-2-lauroyl-sn-glycero-3-phosphocholine (PLPC) lipids and their aldehyde derivatives at a 1 : 1 ratio were studied. Our simulations show that oxidized lipids self-assemble into aggregates with a water pore rapidly developing across the bilayer. The free energy of transporting an α-toc molecule in a bilayer suggests that α-tocs can passively adsorb into it. When α-toc molecules were present at low concentrations in bilayers containing oxidized lipids, water pore formation was slowed down. At high α-toc concentrations, no pores were observed. Based on the simulations, we propose that the mechanism of how α-toc inhibits pore formation in bilayers with oxidized lipids is the following: α-tocs trap the polar groups of the oxidized lipids at the membrane-water interface resulting in a decreased probability of the oxidized lipids making contact with the two leaflets and initiating pore formation. This demonstrates that α-toc molecules not only protect the bilayer from oxidation but also help to stabilize the bilayer after lipid peroxidation occurs. These results will help in designing more efficient molecules to protect membranes from oxidative stress.

Estimation of Oxidative Stress Involvement by Superoxide Dismutase Variation in Cardiac Arrhythmias

Cardiac arrhythmias, commonly diagnosed in young people, involve multiple etiopathogenic factors, including oxidative stress.

PURPOSE

Evaluation of superoxide dismutase (SOD) variations as an antioxidant enzyme (with a physiological role in the dismutation of highly reactive oxygen free radicals into oxygen and water) in young patients with cardiac arrhythmias.

MATERIAL AND METHOD

The study was conducted on a group of 40 young patients with a mean age of 34 years old, of both sexes, with non-lesional cardiac dysrhythmias, compared to a control group of 40 healthy subjects, determining for both groups the SOD serum level. Diagnosis of cardiac rhythm disorder was supported by electrocardiogram, imaging and laboratory investigations.

RESULTS

SOD recorded a 61% decrease of mean values in patients compared to controls. The decreasing variation was found in all arrhythmia types, as follows: atrial fibrillation (51,54%), sinus bradycardia (54,86%), atrial flutter (55,71%), extrasystolic ventricular arrhythmia (64,20%), extrasystolic atrial arrhythmia (65,27%), combined arrhythmias (65,93%), supraventricular paroxysmal tachycardia (71,32%) and sinus tachycardia (74,24%). SOD deficiency demonstrates the involvement of oxidative stress in cardiac arrhythmic pathogenesis, excess oxygen radicals interfering with multiple mechanisms related to the onset of arrhythmogenesis. The SOD decrease was more important in females (60,57%) than in males (67,06%) and in those with nutrition poor in antioxidants.

CONCLUSIONS

SOD estimation represents a biomarker whose decrease and deficiency implies occurrence of oxidative stress and implicitly highlights its role in cardiac arrhythmic pathology in young people, with the possibility of monitoring and correction by pharmacological or non-pharmacological therapeutic means.

Vitamin E Nicotinate

Vitamin E refers to a family of compounds that function as lipid-soluble antioxidants capable of preventing lipid peroxidation. Naturally occurring forms of vitamin E include tocopherols and tocotrienols. Vitamin E in dietary supplements and fortified foods is often an esterified form of α-tocopherol, the most common esters being acetate and succinate. The vitamin E esters are hydrolyzed and converted into free α-tocopherol prior to absorption in the intestinal tract. Because its functions are relevant to many chronic diseases, vitamin E has been extensively studied in respect to a variety of diseases as well as cosmetic applications. The forms of vitamin E most studied are natural α-tocopherol and the esters α-tocopheryl acetate and α-tocopheryl succinate. A small number of studies include or focus on another ester form, α-tocopheryl nicotinate, an ester of vitamin E and niacin. Some of these studies raise the possibility of differences in metabolism and in efficacy between vitamin E nicotinate and other forms of vitamin E. Recently, through metabolomics studies, we identified that α-tocopheryl nicotinate occurs endogenously in the heart and that its level is dramatically decreased in heart failure, indicating the possible biological importance of this vitamin E ester. Since knowledge about vitamin E nicotinate is not readily available in the literature, the purpose of this review is to summarize and evaluate published reports, specifically with respect to α-tocopheryl nicotinate with an emphasis on the differences from natural α-tocopherol or α-tocopheryl acetate.

Antioxidants as therapeutics in the intensive care unit: Have we ticked the redox boxes?

Critically ill patients are under oxidative stress and antioxidant administration reasonably emerged as a promising approach to combat the aberrant redox homeostasis in this patient cohort. However, the results of the antioxidant treatments in the intensive care unit are conflicting and inconclusive. The main objective of the present review is to highlight some inherent, yet widely overlooked redox-related issues about the equivocal effectiveness of antioxidants in the intensive care unit, beyond methodological considerations. In particular, the discrepancy in the literature partially stems from: (1) the largely unspecified role of reactive species in disease onset and progression, (2) our fragmentary understanding on the interplay between inflammation and oxidative stress, (3) the complex spatiotemporal specificity of in vivo redox biology, (4) the pleiotropic effects of antioxidants and (5) the divergent effects of antioxidants according to the temporal administration pattern. In addition, two novel and sophisticated practices with promising pre-clinical results are presented: (1) the selective neutralization of reactive species in key organelles after they are formed (i.e., in mitochondria) and (2) the targeted complete inhibition of dominant reactive species sources (i.e., NADPH oxidases). Finally, the reductive potential of NADPH as a key pharmacological target for redox therapies is rationalized. In light of the above, the recontextualization of knowledge from basic redox biology to translational medicine seems imperative to perform more realistic in vivo studies in the fast-growing field of critical care pharmacology.

Vitamin E slows down the progression of osteoarthritis

Osteoarthritis is a chronic degenerative joint disorder with the characteristics of articular cartilage destruction, subchondral bone alterations and synovitis. Clinical signs and symptoms of osteoarthritis include pain, stiffness, restricted motion and crepitus. It is the major cause of joint dysfunction in developed nations and has enormous social and economic consequences. Current treatments focus on symptomatic relief, however, they lack efficacy in controlling the progression of this disease, which is a leading cause of disability. Vitamin E is safe to use and may delay the progression of osteoarthritis by acting on several aspects of the disease. In this review, how vitamin E may promote the maintenance of skeletal muscle and the regulation of nucleic acid metabolism to delay osteoarthritis progression is explored. In addition, how vitamin E may maintain the function of sex organs and the stability of mast cells, thus conferring a greater resistance to the underlying disease process is also discussed. Finally, the protective effect of vitamin E on the subchondral vascular system, which decreases the reactive remodeling in osteoarthritis, is reviewed.

Protective effect of vitamin E against ethanol-induced small intestine damage in rats

The role of oxidative stress and inflammatory reaction has been reported in various ethanol-induced complications. The purpose of this study was to evaluate the effect of ethanol-induced structural alteration, oxidative stress, and inflammatory reaction on the small intestine of rats, and plausible protective effect of vitamin E to determine whether it inhibits the abnormality induced by ethanol in the small intestine. Twenty-four male wistar rats were divided into three groups, namely: Control, ethanol, and vitamin E treated ethanol groups. After six weeks of treatment, the small intestine length, villus height, crypt depth and muscular layer thickness, oxidative stress, and inflammatory parameters showed significant changes in the ethanol treated group compared to the control group. Vitamin E consumption along with ethanol ameliorated structural alteration of the small intestine and reduced the elevated amount of oxidative stress and inflammatory markers such as protein carbonyl, OX-LDL, IL-6, Hcy, and TNF-α. Furthermore, their total antioxidant capacity was increased significantly compared to that of the ethanol group. These findings indicate that ethanol induces the small intestine abnormality by oxidative and inflammatory stress, and that these effects can be alleviated by using vitamin E as an antioxidant and anti-inflammatory molecule.

The protective effect of vitamin E against prenatal and early postnatal ethanol treatment-induced heart abnormality in rats: a 3-month follow-up study

Ethanol consumption during pregnancy is associated with fetal heart malformation. However, the underlying mechanism of prenatal ethanol exposure causing heart malfunction is not well known. The current study examined the effect of prenatal and early postnatal ethanol consumption on heart abnormality resulting from oxidative and inflammatory stress. It was also intended to find out whether vitamin E inhibits the abnormality induced by ethanol in rats' heart tissue. Pregnant Wistar rats received ethanol with/without vitamin E from the seventh day of gestation (GD7) throughout lactation. The proliferation in heart muscle cells and coronary smooth muscle cells, protein carbonyl, IL-6, TNF-α, homocysteine levels, also lipid profile in heart and plasma of male pups were measured at the end of lactation (PN 21) and 90 days after birth (PN 90). The results indicated proliferation of heart muscle and coronary smooth muscle cells along with heart structural alteration, protein oxidation, lipid peroxidation, inflammatory reaction, and hyperhomocysteinemia in offspring after 21 and 90 days of birth compared with the controls. Vitamin E treatment significantly decreased cell proliferation and heart structural alteration, compared with the group treated by ethanol alone. Furthermore, it reduced the elevation of protein carbonyl, lipid peroxidation, and increased inflammatory proteins to levels as those of the controls. These findings strongly support the idea that ethanol intake by dams during pregnancy and early postnatal days induces heart abnormality mediated by oxidative stress and inflammatory reactions, and that these effects can be alleviated by using vitamin E as an antioxidant and anti-inflammatory molecule.

Effect of α-tocopheryl succinate on the molecular damage induced by indomethacin in C6 glioma cells

Indomethacin is a member of the non-steroidal anti-inflammatory drug (NSAID) class, which has great potential for use in the treatment of glioma. However, it induces the generation of reactive oxygen species (ROS) and causes molecular damage while inducing its effects. Vitamin E is widely used in the complementary therapy of cancers. The main goal of the present study was to investigate the effects of α-tocopheryl succinate (α-TOS) against the oxidative damage induced by indomethacin in C6 glioma cells. Cells were treated with 10 μM α-TOS alone or in combination with 200 μM indomethacin for two days. The intracellular ROS level, molecular damage as revealed by lipid peroxidation and protein carbonyl formation, and the COX activity in C6 glioma cells were measured. Treatment of the cells with α-TOS and indomethacin, alone or in combination, caused the levels of ROS generation and protein damage to increase, but protected against lipid peroxidation and reduced COX activity.

Serum vitamin E concentrations at 1 year and risk of atopy, atopic dermatitis, wheezing, and asthma in childhood: the PASTURE study

BACKGROUND

Prospective studies investigating the role of serum vitamin E concentrations during early life in the development of childhood allergies and asthma are limited.

OBJECTIVE

To study the associations between serum vitamin E concentrations at first year of life and longitudinal development of atopy, atopic dermatitis, wheeze, and asthma up to 6 years of age.

METHODS

The setting was the PASTURE study, a multicenter prospective birth cohort study in five European rural settings. Children of 1133 mothers recruited during pregnancy were followed from birth with measurement of serum vitamin E levels at year 1 and repeated assessments of serum immunoglobulin E antibodies (year 1, 4.5, 6), atopic dermatitis, wheezing symptoms, and asthma (year 1, 1.5, 2, 3, 4, 5, 6).

RESULTS

At 6 years of age, 66% and 82% of the original 1133 subjects underwent blood test for IgE and answered the questionnaire, respectively. We did not observe any statistically significant associations between serum vitamin E concentrations at year 1 and the endpoints, but borderline inverse associations between alpha tocopherol and wheezing without cold (OR 0.45, 95% CI 0.19-1.09) and any wheezing symptom (OR 0.52, 95% CI 0.27-1.02).

CONCLUSIONS

Serum vitamin E concentrations at year 1 were not associated with allergies or asthma by 6 years of age. While further prospective studies with repeated assessments of vitamin E during early life may clarify its putative role in the development of the diseases, it is also possible that the antioxidant hypothesis in the development of allergies and asthma does not hold.

Mild systemic oxidative stress in the subclinical stage of Alzheimer's disease

Alzheimer's disease (AD) is a late-onset, progressive degenerative disorder that affects mainly the judgment, emotional stability, and memory domains. AD is the outcome of a complex interaction among several factors which are not fully understood yet; nevertheless, it is clear that oxidative stress and inflammatory pathways are among these factors. 65 elderly subjects (42 cognitively intact and 23 with probable Alzheimer's disease) were selected for this study. We evaluated erythrocyte activities of superoxide dismutase, catalase, and glutathione peroxidase as well as plasma levels of total glutathione, α-tocopherol, β-carotene, lycopene, and coenzyme Q10. These antioxidant parameters were confronted with plasmatic levels of protein and lipid oxidation products. Additionally, we measured basal expression of monocyte HLA-DR and CD-11b, as well as monocyte production of cytokines IL1-α, IL-6, and TNF-α. AD patients presented lower plasmatic levels of α-tocopherol when compared to control ones and also higher basal monocyte HLA-DR expression associated with higher IL-1α production when stimulated by LPS. These findings support the inflammatory theory of AD and point out that this disease is associated with a higher basal activation of circulating monocytes that may be a result of α-tocopherol stock depletion.

Biomarkers of oxidative stress, antioxidant defence and inflammation are altered in the senescence-accelerated mouse prone 8

In this study we compared biomarkers of oxidative stress, stress response, antioxidant defence and inflammation between mice (n = 10 per group, female, 7 months old) with an accelerated (SAMP8) and a normal ageing phenotype (SAMR1). As compared to SAMR1 mice, SAMP8 mice exhibited higher levels of lipid peroxides and protein carbonyls as well as a lower activity of the proteasomal subunit β-5. Furthermore, heme oxygenase-1 and paraoxonase-1 (PON-1) status was lower in SAMP8 mice indicating impaired stress response. Biomarkers of inflammation such as C-reactive protein and serum amyloid P were elevated in SAMP8 mice. Interestingly, impaired stress response and increased inflammation in SAMP8 mice were associated with elevated concentrations of ascorbic acid and α-tocopherol in the liver. An age-dependent increase in hepatic vitamin E and a decline in PON-1 gene expression were also observed in aged compared to young C57BL/6 mice.

Pioglitazone protects HDL(2&3) against oxidation in overweight and obese men

BACKGROUND

The worldwide epidemic of obesity is a major public health concern and is persuasively linked to the rising prevalence of diabetes and cardiovascular disease. Obesity is often associated with an abnormal lipoprotein profile, which may be partly negated by pioglitazone intervention, as this can influence the composition and oxidation characteristics of low-density lipoprotein (LDL). However, as pioglitazone's impact on these parameters within high-density lipoprotein (HDL), specifically HDL(2&3), is absent from the literature, this study was performed to address this shortcoming.

METHODS

Twenty men were randomized to placebo or pioglitazone (30 mg/day) for 12 weeks. HDL(2&3) were isolated by rapid-ultracentrifugation. HDL(2&3)-cholesterol and phospholipid content were assessed by enzymatic assays and apolipoprotein AI (apoAI) content by single-radial immunodiffusion. HDL(2&3) oxidation characteristics were assessed by monitoring conjugated diene production and paraoxonase-1 activity by spectrophotometric assays.

RESULTS

Compared with the placebo group, pioglitazone influenced the composition and oxidation potential of HDL(2&3). Specifically, total cholesterol (P < 0.05), phospholipid (P < 0.001) and apoAI (P < 0.001) were enriched within HDL(2). Furthermore, the resistance of HDL(2&3) to oxidation (P < 0.05) and the activity of paroxonase-1 were also increased (P < 0.001).

CONCLUSIONS

Overall, these findings indicate that pioglitazone treatment induced antiatherogenic changes within HDL(2&3), which may help reduce the incidence of premature cardiovascular disease linked with obesity.

Simultaneous extraction and quantitation of carotenoids, chlorophylls, and tocopherols in Brassica vegetables

Brassica oleracea vegetables, such as broccoli (B. oleracea L. var. italica) and cauliflower (B. oleracea L. var. botrytis), are known to contain bioactive compounds associated with health, including three classes of photosynthetic lipid-soluble compounds: carotenoids, chlorophylls, and tocopherols. Carotenoids and chlorophylls are photosynthetic pigments. Tocopherols have vitamin E activity. Due to genetic and environmental variables, the amounts present in vegetables are not constant. To aid breeders in the development of Brassica cultivars with higher provitamin A and vitamin E contents and antioxidant activity, a more efficient method was developed to quantitate carotenoids, chlorophylls, and tocopherols in the edible portions of broccoli and cauliflower. The novel UPLC method separated five carotenoids, two chlorophylls, and two tocopherols in a single 30 min run, reducing the run time by half compared to previously published protocols. The objective of the study was to develop a faster, more effective extraction and quantitation methodology to screen large populations of Brassica germplasm, thus aiding breeders in producing superior vegetables with enhanced phytonutrient profiles.

γ-Tocotrienol induces growth arrest through a novel pathway with TGFβ2 in prostate cancer

Regions along the Mediterranean and in southern Asia have lower prostate cancer incidence compared to the rest of the world. It has been hypothesized that one of the potential contributing factors for this low incidence includes a higher intake of tocotrienols. Here we examine the potential of γ-tocotrienol (GT3) to reduce prostate cancer proliferation and focus on elucidating pathways by which GT3 could exert a growth-inhibitory effect on prostate cancer cells. We find that the γ and δ isoforms of tocotrienol are more effective at inhibiting the growth of prostate cancer cell lines (PC-3 and LNCaP) compared with the γ and δ forms of tocopherol. Knockout of PPAR-γ and GT3 treatment show inhibition of prostate cancer cell growth, through a partially PPAR-γ-dependent mechanism. GT3 treatment increases the levels of the 15-lipoxygenase-2 enzyme, which is responsible for the conversion of arachidonic acid to the PPAR-γ-activating ligand 15-S-hydroxyeicosatrienoic acid. In addition, the latent precursor and the mature forms of TGFβ2 are down-regulated after treatment with GT3, with concomitant disruptions in TGFβ receptor I, SMAD-2, p38, and NF-κB signaling.

Reactive oxygen species: impact on skeletal muscle

It is well established that contracting muscles produce both reactive oxygen and nitrogen species. Although the sources of oxidant production during exercise continue to be debated, growing evidence suggests that mitochondria are not the dominant source. Regardless of the sources of oxidants in contracting muscles, intense and prolonged exercise can result in oxidative damage to both proteins and lipids in the contracting myocytes. Further, oxidants regulate numerous cell signaling pathways and modulate the expression of many genes. This oxidant-mediated change in gene expression involves changes at transcriptional, mRNA stability, and signal transduction levels. Furthermore, numerous products associated with oxidant-modulated genes have been identified and include antioxidant enzymes, stress proteins, and mitochondrial electron transport proteins. Interestingly, low and physiological levels of reactive oxygen species are required for normal force production in skeletal muscle, but high levels of reactive oxygen species result in contractile dysfunction and fatigue. Ongoing research continues to explore the redox-sensitive targets in muscle that are responsible for both redox regulation of muscle adaptation and oxidant-mediated muscle fatigue.

Oxidative stress and longevity in okinawa: an investigation of blood lipid peroxidation and tocopherol in okinawan centenarians

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.

Diet and asthma: nutrition implications from prevention to treatment

Asthma is characterized by lung airway inflammation initiated and perpetuated by an inappropriate immune response, increased airway responsiveness, and variable airflow obstruction. In Western countries there has been a marked increase in asthma prevalence such that it has become a public health concern. It has been hypothesized that the increase may be due to changing antioxidant intake, increasing dietary ratio of n-6:n-3 polyunsaturated fatty acids (PUFA), and vitamin D deficiency (and supplementation). Observational studies have reported associations between asthma and dietary antioxidants (vitamin E, vitamin C, carotenoids, selenium, polyphenols, and fruit), PUFA, and vitamin D. However, supplementing the diets of adults with asthma with antioxidants and n-3 PUFA has minimal, if any, clinical benefit. Currently there is insufficient evidence to support the use of nutrient supplements to complement conventional treatment; however, results of ongoing studies are awaited, and additional research is required, particularly in children. Interest in the potential of dietary intervention during pregnancy to reduce the likelihood of childhood asthma has increased. A small number of cohort studies have highlighted associations between childhood asthma and reduced maternal intake of some nutrients (vitamin E, vitamin D, selenium, zinc, and PUFA) during pregnancy. Although vitamin D intervention studies during pregnancy are ongoing and two intervention studies suggest that dietary PUFA manipulation during pregnancy may be advantageous, further trials are needed to establish if modification of maternal nutrient intake during pregnancy can be used as a healthy, low cost, public health measure to reduce the prevalence of childhood asthma.

Ethanol influences on Bax translocation, mitochondrial membrane potential, and reactive oxygen species generation are modulated by vitamin E and brain-derived neurotrophic factor

BACKGROUND

This study investigated ethanol influences on intracellular events that predispose developing neurons toward apoptosis and the capacity of the antioxidant α-tocopherol (vitamin E) and the neurotrophin brain-derived neurotrophic factor (BDNF) to modulate these effects. Assessments were made of the following: (i) ethanol-induced translocation of the pro-apoptotic Bax protein to the mitochondrial membrane, a key upstream event in the initiation of apoptotic cell death; (ii) disruption of the mitochondrial membrane potential (MMP) as a result of ethanol exposure, an important process in triggering the apoptotic cascade; and (iii) generation of damaging reactive oxygen species (ROS) as a function of ethanol exposure.

METHODS

These interactions were investigated in cultured postnatal day 8 neonatal rat cerebellar granule cells, a population vulnerable to developmental ethanol exposure in vivo and in vitro. Bax mitochondrial translocation was analyzed via subcellular fractionation followed by Western blot, and mitochondrial membrane integrity was determined using the lipophilic dye, JC-1, that exhibits potential-dependent accumulation in the mitochondrial membrane as a function of the MMP.

RESULTS

Brief ethanol exposure in these preparations precipitated Bax translocation, but both vitamin E and BDNF reduced this effect to control levels. Ethanol treatment also resulted in a disturbance of the MMP, and this effect was blunted by the antioxidant and the neurotrophin. ROS generation was enhanced by a short ethanol exposure in these cells, but the production of these harmful free radicals was diminished to control levels by cotreatment with either vitamin E or BDNF.

CONCLUSIONS

These results indicate that both antioxidants and neurotrophic factors have the potential to ameliorate ethanol neurotoxicity and suggest possible interventions that could be implemented in preventing or lessening the severity of the damaging effects of ethanol in the developing central nervous system seen in the fetal alcohol syndrome (FAS).

Strategies for the discovery of anti-aging compounds

IMPORTANCE OF THE FIELD

Life expectancy has increased across the globe and the number of aged people is increasing rapidly. With the rise in the average age of people, the prevalence of age related pathologies has also increased and thus the strategies to find anti-aging molecules assume significance. Anti-aging basically concerns the prevention or delaying the alterations taking place as a function of age which are manifested as age-associated illnesses.

AREAS COVERED IN THIS REVIEW

This review covers anti-aging strategies involving supplementation of dietary antioxidants such as polyphenols, vitamins E and C, lipoic acid, acetyl carnitine, carnosine and cysteine along with the application of mammalian target of rapamycin inhibitors and plasma membrane redox system activators. It also presents the use of different hormone supplementation, for example, melatonin, dehydroepiandrosterone, growth hormone and sex hormones as a tool against aging. The use of caloric restriction and calorie restriction mimetics as an anti-aging intervention is also reviewed.

WHAT THE READER WILL GAIN

The concept, use and efficacy of different anti-aging approaches.

TAKE HOME MESSAGE

Despite a lot of research and sustained ongoing efforts, finding a viable anti-aging therapy which can extend the maximum human lifespan remains elusive. However, several interventions aimed towards a longer healthy life seem promising.

Session 1: Allergic disease: Nutrition as a potential determinant of asthma

Asthma is characterised by chronic lung airway inflammation, increased airway responsiveness and variable airflow obstruction. In Westernised countries asthma is a public health concern because of its prevalence, associated ill health and high societal and healthcare costs. In recent decades there has been a marked increase in asthma prevalence, particularly in Westernised countries. It has been proposed that changing diet has contributed to the increase in asthma. Several dietary hypotheses exist; the first relates the increase in asthma to declining dietary antioxidant intake, the second to decreased intake of long-chain n-3 PUFA and increasing intake of n-6 PUFA. Vitamin D supplementation and deficiency have also been hypothesised to have contributed to the increase in asthma. Observational studies have reported associations between asthma and dietary antioxidants (vitamin E, vitamin C, carotenoids, Se, flavonoids, fruit), lipids (PUFA, butter, margarine, fish) and vitamin D. However, supplementing the diets of adults with asthma with antioxidants and lipids has minimal, if any, clinical benefit. There is growing interest in the possibility that childhood asthma is influenced by maternal diet during pregnancy, with studies highlighting associations between childhood asthma and maternal intake of some nutrients (vitamin E, vitamin D, Se, PUFA) during pregnancy. It has been suggested that maternal diet during pregnancy influences fetal airway and/or immune development. Further intervention studies are needed to establish whether modification of maternal nutrient intake during pregnancy can be used as a healthy low-cost public health measure to reduce the prevalence of childhood asthma.

Antioxidants and allergic disease: a case of too little or too much?

Speculation persists as to the possible role, if any, of dietary antioxidants in allergic disease. While it has been hypothesized that the recent increase in allergic disease is a consequence of declining dietary antioxidant intake, an alternative hypothesis proposes that the increase in allergic disease is due to increasing antioxidant intake. Dietary trends are conflicting; the intake of some antioxidants has declined, for others intakes are likely to have increased. Animal model studies demonstrate that antioxidant supplementation at the time of primary and subsequent allergen exposure attenuates allergic inflammatory responses. The data from human studies are less clear. Observational epidemiological studies of humans are beset by several methodological limitations associated with the assessment of diet and predominantly focus on asthma. Most observational studies report potentially beneficial associations between dietary antioxidants and allergic outcomes, but a small minority report potentially adverse associations. Human intervention studies suggest that single antioxidant supplements confer minimal, if any clinical benefit in adults with asthma, however, there is still scope for studies in children, atopic dermatitis, allergic rhinitis (AR) and of antioxidant combinations. More recently, it has been suggested that dietary antioxidants in the developmental context of fetal and infant development influence the development childhood asthma and atopic sensitization possibly by affecting the first interactions between the neonatal immune system and allergens. While a small number of birth cohort studies have reported potentially beneficial associations between maternal intake of some antioxidants during pregnancy and childhood asthma, there is very limited data suggesting associations between maternal antioxidant intake and childhood atopic dermatitis and AR. The available epidemiological, animal, molecular and immunological data suggest that there are associations between antioxidants and asthma and to a much lesser extent, atopic dermatitis and AR. However, the exact nature of the relationships and the potential for therapeutic intervention remain unclear.

Glycosidic moiety changes the spectroscopic properties of dl-alpha-tocopherol in DMSO/water solution and in organic solvents

In this study we estimated how conjugation with a sugar moiety influences the spectral properties of tocopherol and relate the spectroscopic properties of glycosides to solvent properties such as viscosity and polarity. Spectroscopic properties (absorption, fluorescence, fluorescence anisotropy and fluorescence lifetime) of three dl-alpha-tocopheryl glycosides (dl-alpha-tocopheryl orthoacetate derivative and glycosides of dl-alpha-tocopherol model compounds: 2,2,5,7,8-pentamethyl-6-chromanol and Trolox) were studied in DMSO/water solution. In all investigated compounds dissolved in DMSO/water mixture the absorption and emission maxima were blue-shifted. The fluorescence lifetimes were longer compared with those obtained for the parent compounds, except for the Trolox glucoside, in which it was shorter. The observed effect is connected with an increase in the electronic energy in the ground state due to electron rearrangement in the chromanol system caused by interaction with the sugar moiety. The extent of the spectral shift is related to the sugar moiety substituted at the phenolic oxygen rather than to substitution at the 2a position in the chromanol ring. The fluorescent properties of dl-alpha-tocopheryl glucoside in organic solvents were measured. The Stokes shift was related to the orientational polarizability of the solvents. The study of viscosity suggested two different mechanisms explaining the results observed in a low- and high-viscosity environment. The results indicated the fundamental role of interactions between the chromophore and sugar moiety in a low-viscosity environment. The results obtained at high values of viscosity are discussed in terms of a frictional boundary solvent-solute interaction model.

Vitamin E deficiency induces liver nuclear factor-κB DNA-binding activity and changes in related genes

The biological functions of vitamin E have been classically attributed to its property as a potent inhibitor of lipid peroxidation in cellular membranes. However, in 1991, Azzi's group first described that alpha-tocopherol inhibits smooth muscle cell proliferation in a protein kinase C (PKC)-dependent way, demonstrating a non-antioxidant cell signalling function for vitamin E. More recently, the capacity of alpha-tocopherol to modulate gene expression with the implication of different transcription factors, beyond its antioxidant properties, has also been established. This study was to determine the effect of vitamin E-deficiency on liver nuclear factor-kappa B (NF-kappaB) DNA-binding activity and the response of target antioxidant-defense genes and cell cycle modulators. Rats were fed either control diet or vitamin-E free diet until 60 or 90 days after birth. Vitamin E-deficiency enhanced liver DNA-binding activity of NF-kappaB [electrophoretic mobility-shift assay, (EMSA)] and up-regulated transcription of gamma-glutamylcysteine synthetase (gamma-GCSM; gamma-GCSC), cyclin D1 and cyclin E. We also showed down-regulation of p21(Waf1/Cip1) transcription. Western-blot analysis demonstrated that gamma-glutamylcysteine synthetase catalytic subunit (gamma-GCSC) and cyclin D1 showed a similar pattern to that found in the RT-PCR analysis. Moreover, chromatin immunoprecipitation (ChIP) assay demonstrated that NF-kappaB directly regulates transcription of gamma-GCS (both subunits) and cyclin D1 through the binding of NF-kappaB to the corresponding gene promoters, which was enhanced in vitamin E-deficiency. These findings show that vitamin E-deficiency induces significant molecular regulatory properties in liver cells with an altered expression of both antioxidant-defense genes and genes that control the cell cycle and demonstrate that liver NF-kappaB activation is involved in this response. Our results emphasize the importance of maintaining an adequate vitamin E consumption not only to prevent liver oxidative damage but also in modulating signal transduction.

Feasibility for improving phytonutrient content in vegetable crops using conventional breeding strategies: case study with carotenoids and tocopherols in sweet corn and broccoli

Among vegetables, sweet corn ( Zea mays L.) and broccoli ( Brassica oleracea L. ssp. italica) are important sources of dietary carotenoids and tocopherols. Because medical evidence suggests that carotenoid and tocopherol health-promoting activity acts in a dose-dependent manner, conventional breeding to develop elite sweet corn and broccoli germplasm with enhanced levels of these phytochemicals will potentially promote health among the consuming public. This investigation includes the quantitative analysis of carotenoid and tocopherol contents of 41 corn and 24 broccoli genotypes grown in multiple environments (years and seasons in one location) to partition the variation into genetic, environment, and genotype by environment interaction (GxE) components and measure the phenotypic stability of genotypes for these phytochemicals. The primary carotenoids and tocopherols in corn were lutein and gamma-tocopherol (65 and 73% of total carotenoid and tocopherol, respectively), whereas beta-carotene and alpha-tocopherol were dominant in broccoli (65 and 79% of total carotenoid and tocopherol, respectively). Partitioning of the variance indicated that genetic differences among the genotypes averaged for the primary compounds in corn (lutein, zeaxanthin, and alpha- and gamma-tocopherol) and broccoli (beta-carotene, lutein, and alpha- and gamma-tocopherol) accounted for the largest proportion of the variation (67 and 55% of total phenotypic variation averaged across the phytochemicals in sweet corn and broccoli, respectively). Stability analysis identified several corn (IL451b sh2 and IL2027-8 sh2) and broccoli ('Pirate' and 'Baccus') genotypes with relatively high mean concentrations for the various carotenoids and tocopherols that were comparatively stable across seasons and years. The results of this investigation suggest that sweet corn and broccoli germplasm with enhanced concentrations of carotenoids and tocopherols can be developed using conventional breeding protocols.

Influence of dietary vitamin E supplementation on meat quality traits and gene expression related to lipid metabolism in the Beijing-you chicken

1. The effects of dietary vitamin E (DL-alpha-tocopheryl acetate) on carcase and meat quality, oxidative stability, fatty acid composition of muscle lipids, and gene expression related to lipid metabolism were studied in Beijing-you chickens. 2. A total of 360 female birds were distributed among 6 treatments, containing 6 replicates, each of 10 birds. The feed for each treatment was supplemented with vitamin E (0, 10, 50, 100, 150, or 200 mg/kg feed). At 120 d, 30 birds from each treatment were slaughtered to examine the effect of dietary vitamin E supplementation on evaluated traits. 3. The results showed that supplemental vitamin E in diet significantly increased alpha-tocopherol contents of breast and thigh muscles, reduced the drip loss and improved tenderness but did not influence carcase yield, meat colour or pH value 24 h after slaughter. 4. Thiobarbituric acid reactive substance (TBARS) values decreased with increase in dietary vitamin E, and the addition of 100 mg/kg or more vitamin E had a beneficial effect on oxidative stability as indicated by TBARS values during storage up to 7 d. 5. Dietary vitamin E supplementation significantly altered fatty acid composition of breast muscle. Supplementing with 200 mg/kg vitamin E led to lower saturated fatty acids and greater polyunsaturated fatty acids proportions in breast muscle than control and 10 mg/kg vitamin E treatments. 6. Vitamin E supplementation significantly inhibited expression of the cytosolic phospholipase A(2) gene (cPLA(2)) in breast muscle, while enhancing that of the peroxisome proliterator-activated receptor beta (PPAP-beta) and heart fatty acid binding protein genes (H-FABP). The results indicate that dietary supplementation with vitamin E increased lipid stability in muscle and improved meat quality and fatty acid composition, probably by its influence on the expression of genes related to lipid metabolism.

Fresh soy oil protects against vascular changes in an estrogen-deficient rat model: an electron microscopy study

OBJECTIVE

To observe the effects of consuming repeatedly heated soy oil on the aortic tissues of estrogen-deficient rats.

METHODS

Thirty female Sprague Dawley rats (200-250 g) were divided equally into five groups. One group served as the normal control (NC) group. The four treated groups were ovariectomized and were fed as follows: 2% cholesterol diet (OVXC); 2% cholesterol diet + fresh soy oil (FSO); 2% cholesterol diet + once-heated soy oil (1HSO); and 2% cholesterol diet + five-times-heated soy oil (5HSO). After four months, the rats were sacrificed, and the aortic tissues were obtained for histological studies.

RESULTS

After four months of feeding, the NC, FSO and 1HSO groups had a lower body weight gain compared to the OVXC and 5HSO groups. The tunica intima/media ratio in the 5HSO group was significantly thicker (p < 0.05) compared to the NC, OVXC and FSO groups. Electron microscopy showed that endothelial cells were normally shaped in the FSO and NC groups but irregular in the 1HSO and 5HSO groups. A greater number of collagen fibers and vacuoles were observed in the 5HSO group compared to the other treatment groups.

CONCLUSIONS

Fresh soy oil offered protection in the estrogen-deficient state, as these rats had similar features to those of the NC group. The damage to the tunica intima and the increase in the ratio of tunica intima/media thickness showed the deleterious effect of consuming repeatedly heated soy oil in castrated female rats.

Cholinergic degeneration and memory loss delayed by vitamin E in a Down syndrome mouse model

Down syndrome (DS) individuals develop several neuropathological hallmarks seen in Alzheimer's disease, including cognitive decline and the early loss of cholinergic markers in the basal forebrain. These deficits are replicated in the Ts65Dn mouse, which contains a partial trisomy of murine chromosome 16, the orthologous genetic segment to human chromosome 21. Oxidative stress levels are elevated early in DS, and may contribute to the neurodegeneration seen in these individuals. We evaluated oxidative stress in Ts65Dn mice, and assessed the efficacy of long-term antioxidant supplementation on memory and basal forebrain pathology. We report that oxidative stress was elevated in the adult Ts65Dn brain, and that supplementation with the antioxidant vitamin E effectively reduced these markers. Also, Ts65Dn mice receiving vitamin E exhibited improved performance on a spatial working memory task and showed an attenuation of cholinergic neuron pathology in the basal forebrain. This study provides evidence that vitamin E delays onset of cognitive and morphological abnormalities in a mouse model of DS, and may represent a safe and effective treatment early in the progression of DS neuropathology.

Exercise-induced oxidative stress: cellular mechanisms and impact on muscle force production

The first suggestion that physical exercise results in free radical-mediated damage to tissues appeared in 1978, and the past three decades have resulted in a large growth of knowledge regarding exercise and oxidative stress. Although the sources of oxidant production during exercise continue to be debated, it is now well established that both resting and contracting skeletal muscles produce reactive oxygen species and reactive nitrogen species. Importantly, intense and prolonged exercise can result in oxidative damage to both proteins and lipids in the contracting myocytes. Furthermore, oxidants can modulate a number of cell signaling pathways and regulate the expression of multiple genes in eukaryotic cells. This oxidant-mediated change in gene expression involves changes at transcriptional, mRNA stability, and signal transduction levels. Furthermore, numerous products associated with oxidant-modulated genes have been identified and include antioxidant enzymes, stress proteins, DNA repair proteins, and mitochondrial electron transport proteins. Interestingly, low and physiological levels of reactive oxygen species are required for normal force production in skeletal muscle, but high levels of reactive oxygen species promote contractile dysfunction resulting in muscle weakness and fatigue. Ongoing research continues to probe the mechanisms by which oxidants influence skeletal muscle contractile properties and to explore interventions capable of protecting muscle from oxidant-mediated dysfunction.

Vitamin E: An overview of major research directions

During the last 90 years since the discovery of vitamin E, research has focused on different properties of this molecule, the focus often depending on the specific techniques and scientific knowledge present at each time. Originally discovered as a dietary factor essential for reproduction in rats, vitamin E has revealed in the meantime many more important molecular properties, such as the scavenging of reactive oxygen and nitrogen species with consequent prevention of oxidative damage associated with many diseases, or the modulation of signal transduction and gene expression in antioxidant and non-antioxidant manners. Research over the last 30 years has also resolved the biosynthesis and occurrence of vitamin E in plants, the proteins involved in the cellular uptake, tissue distribution and metabolism, and defined a congenital recessive neurological disease, ataxia with vitamin E deficiency (AVED), characterized by impaired enrichment of alpha-tocopherol in plasma as a result of mutations in the liver alpha-tocopherol transfer gene. This review is giving a brief introduction about vitamin E by following the major research directions since its discovery with a historical perspective.

Regulatory role of vitamins E and C on extracellular matrix components of the vascular system

The protective effect of vitamins E (alpha-tocopherol) and C (L-ascorbic acid) in the prevention of cardiovascular disease (CVD) has been shown in a number of situations but a secure correlation is not universally accepted. Under certain conditions, both, L-ascorbic acid and alpha-tocopherol can exhibit antioxidant properties and thus may reduce the formation of oxidized small molecules, proteins and lipids, which are a possible cause of cellular de-regulation. However, non-antioxidant effects have also been suggested to play a role in the prevention of atherosclerosis. Vitamin E and C can modulate signal transduction and gene expression and thus affect many cellular reactions such as the proliferation of smooth muscle cells, the expression of cell adhesion and extracellular matrix molecules, the production of O(2)(-) by NADPH-oxidase, the aggregation of platelets and the inflammatory response. Vitamins E and C may modulate the extracellular matrix environment by affecting VSMC differentiation and the expression of connective tissue proteins involved in vascular remodeling as well as the maintenance of vascular wall integrity. This review summarizes individually the molecular activities of vitamins E and C on the cells within the connective tissue of the vasculature, which are centrally involved in the maintenance of an intact vascular wall as well as in the repair of atherosclerotic lesions during disease development.

Clinical trials of natural products as chemopreventive agents for prostate cancer

Epidemiological research on prostate cancer risk in men throughout the world has identified significant correlations between dietary habits and prostate cancer occurrence. These studies served as a catalyst for exploration into the potential of dietary substances to act as chemopreventive agents against this disease, and include green tea catechins, lycopene, soy isoflavones, pomegranate phenolics, selenium, vitamins E and D, curcumin and resveratrol. Before these agents (in the dietary or purified forms) can be recommended as useful chemopreventive strategies for patients, their activity must be confirmed in rigorously designed clinical trials. This review discusses the preclinical and clinical data available for these dietary agents and describes relevant clinical trials currently being conducted.

The increase in the prevalence of asthma and allergy: food for thought

Since about 1960, the prevalence of asthma and allergic disease has increased sufficiently to become a major public-health concern. Concurrently, there have been marked changes in our diet, and it has been proposed that these changes have contributed to the increase in the prevalence of asthma and allergy. In this article, these hypotheses about diet are described, together with the postulated mechanisms and the evidence for and against, leading to the most recent evidence indicating that maternal diet during pregnancy might be particularly important in the development of childhood asthma.