Reflections on a century of vitamin E research: Looking at the past with an eye on the future

Perceiving the functions of vitamin E through neutron and X-ray scattering

Take your vitamins, or don't? Vitamin E is one of the few lipophilic vitamins in the human diet and is considered an essential nutrient. Over the years it has proven to be a powerful antioxidant and is commercially used as such, but this association is far from linear in physiology. It is increasingly more likely that vitamin E has multiple legitimate biological roles. Here, we review past and current work using neutron and X-ray scattering to elucidate the influence of vitamin E on key features of model membranes that can translate to the biological function(s) of vitamin E. Although progress is being made, the hundred year-old mystery remains unsolved.

The potential ameliorating effect of vitamin E on bleomycin - induced lung fibrosis in adult albino rats

Lung fibrosis is a critical interstitial lung disease with poor prognosis. There is an urgent need to develop a proper and cost-effective therapeutic modality that can reverse and/or ameliorate lung fibrosis. Vitamin E is one of the widely investigated dietary antioxidants which has been linked to improvement of many health problems. The current study was conducted to evaluate the possible roles of vitamin E in prevention and treatment of bleomycin (BLM) induced lung fibrosis. Physiological, anatomical, histopathological and immunohistochemical studies were done to assess and compare between the structure and function of the lung tissue in lung fibrosis model, early and late treated groups with vitamin E. Furthermore, measurement of transforming growth factor-β(TGF-β), E-cadherin, Smad-3, BAX, BCL2, malondialdehyde (MDA), and superoxide dismutase (SOD) were done. The study revealed that administration of vitamin E helped to improve signs of lung fibrosis, as reflected by amelioration of structure and functions of lungs as well as the decrease in TGF-β levels and inhibition of α-SMA/collagen I profibrotic pathway. These findings highlight the importance of administration of vitamin E as a prophylactic agent prior to BLM therapy and as an adjuvant treatment in cases of lung fibrosis.

Antioxidant interaction between α-tocopherol and γ-oryzanol in HepG2 cells

Minor constituents exhibit certain antioxidant interactions in vitro, and the effects in different media are different. However, it is not clear whether there are antioxidant interactions in cells after digestion and absorption. We utilized the cellular antioxidant evaluation model in HepG2 cells to study the antioxidant interaction between α-tocopherol and γ-oryzanol, and the interaction mechanism of a binary mixture was also illustrated. A cellular antioxidant assay (CAA) model and a combined index (CI) method were firstly used to explore the antioxidant activity and interaction of the binary mixture in HepG2 cells. The CAA value was positively correlated with the single addition concentration, while the results displayed a biphasic tendency with increasing concentrations of the binary mixture. The combination of TO11 (1 μg mL-1 α-tocopherol and 10 μg mL-1 γ-oryzanol) showed the greatest antioxidant activity and synergistic effect, and the maximum CAA value reached up to 94.84 ± 4.2. Then the mechanism of the synergistic antioxidant effect of the binary mixture was explained from three aspects including cellular uptake, intracellular reactive oxygen species (ROS) level and endogenous enzyme activity. The results demonstrated that the antioxidant interaction of the binary mixture in cells was related to cellular uptake of minor constituents, and the combination of TO11 exerted a synergistic effect by scavenging ROS and up-regulating glutathione peroxidase (GSH-Px) activity, resulting in the strongest cellular antioxidant activity. This study throws light on the nature of antioxidant interaction between minor constituents, which may contribute to the development of related functional foods and rational dietary collocation.

Understanding mechanisms of antioxidant action in health and disease

Several different reactive oxygen species (ROS) are generated in vivo. They have roles in the development of certain human diseases whilst also performing physiological functions. ROS are counterbalanced by an antioxidant defence network, which functions to modulate ROS levels to allow their physiological roles whilst minimizing the oxidative damage they cause that can contribute to disease development. This Review describes the mechanisms of action of antioxidants synthesized in vivo, antioxidants derived from the human diet and synthetic antioxidants developed as therapeutic agents, with a focus on the gaps in our current knowledge and the approaches needed to close them. The Review also explores the reasons behind the successes and failures of antioxidants in treating or preventing human disease. Antioxidants may have special roles in the gastrointestinal tract, and many lifestyle features known to promote health (especially diet, exercise and the control of blood glucose and cholesterol levels) may be acting, at least in part, by antioxidant mechanisms. Certain reactive sulfur species may be important antioxidants but more accurate determinations of their concentrations in vivo are needed to help assess their contributions.

Vitamin E and Diabetic Foot Ulcers

This narrative mini-review discusses vitamin E levels in subjects with diabetic foot ulcers (DFUs). Vitamin E may be reduced in subjects with DFUs, but this finding is inconsistent. Its administration appears to benefit patients with DM, delaying the onset of complications, including DFUs. There is also evidence that it may promote DFUs healing. Nonetheless, further studies are required to confirm these promising results and estimate vitamin E administration's costeffectiveness.

Prevalence of vitamin E inadequacy, dietary intake and sources of alpha-tocopherol, and predictors of alpha- and gamma-tocopherol status in adolescent girls in Central Mozambique

An adequate alpha-tocopherol status is important for females at reproductive age. We studied the dietary intake and sources of alpha-tocopherol and alpha- and gamma-tocopherol status indicators in 14-19-year-old girls in Central Mozambique. We also explored factors associated with alpha- and gamma-tocopherol status. The participants (n 508) were from the cross-sectional ZANE Study that was conducted in 2010. We recruited two separate samples, one in January-February and the other in May-June. We collected venous blood samples and conducted 24 h dietary recall interviews. At the time of blood sampling, 11 % of participants were pregnant and 10 % were lactating. In the total sample, both seasons combined, the median intake of alpha-tocopherol was 6⋅7 mg/d, the mean plasma alpha- and gamma-tocopherol concentrations were 13⋅5 and 0⋅75 μmol/l, respectively, and the prevalence of vitamin E inadequacy (alpha-tocopherol <12 μmol/l) was 36⋅7 % (95 % CI: 31⋅9-42⋅0 %). Season and lactation status were significant predictors of alpha-tocopherol status regardless of which the three indicators (plasma concentration, alpha-tocopherol:total cholesterol ratio, gamma-tocopherol:alpha-tocopherol ratio) were used. Being a lactating mother was negatively associated and having a blood sample taken in January-February, when the main sources of alpha-tocopherol were mango and dark green leafy vegetables, was positively associated with alpha-tocopherol status. In conclusion, vitamin E inadequacy was common in Central Mozambique, and the status may fluctuate due to seasonal changes in the diet. We suggest that lactating mothers are specifically at risk of poor alpha-tocopherol status in resource-poor settings.

Telescoping-Solvation-Box Protocol-Based Umbrella Sampling Method for Potential Mean Force Estimation

Previously, it was shown that the telescoping box scheme, in combination with adaptive steered molecule dynamics (ASMD), can be used to estimate the potential of mean force (PMF) with a decrease in computational cost associated with large solvation boxes. Since ASMD reduces to umbrella sampling (US) in the limit of infinitely slow pulling velocity, a hypothesis was made that the telescoping box scheme can be extended to include the US method. The hypothesis was tested using the unfolding pathway of a polyalanine peptide in a water box and translocation of α-tocopherol through the human membrane. Two different approaches were tried: telescoping US (TELUS), in which the number of solvent molecules was linearly coupled to the reaction coordinate, and Block-TELUS, which was a compromise between the fixed solvation box of the US and the window-wise variable solvation box of TELUS. In the case of polyalanine peptide in a water box, both approaches gave overlapping potential of mean force (PMF) concerning the benchmark US-PMF. Window-wise comparison of properties like root-mean-square inner product, Ramachandran plot, α-helix content, and hydrogen bond formation was used to verify that both approaches captured the same dynamics as the US method. Applying the Block-TELUS protocol in the system with diffusing α-tocopherol through the bilayer resulted in overlapping PMF to its US benchmark. A comparison between the window-wise orientation of the chromanol headgroup also produced almost identical results. This study concluded that with the careful application of telescoping solvation boxes, a less computationally expensive US could be performed for systems where the effect of distant solvent molecules on the configurational space sampled in the window depends on the value of the reaction coordinate.

Vitamin E discussion forum position paper on the revision of the nomenclature of vitamin E

This position paper opens a discussion forum of this Journal dedicated to a scientific debate on Vitamin E nomenclature. With this article we provide the scientific and medical communities with what we consider relevant information in favor of revising the nomenclature of vitamin E. To our knowledge, only RRR-α-tocopherol has been medically used to protect against a deficiency disease in humans, and therefore, it would be appropriate to restrict the term vitamin to this molecule. The direct demonstration of a vitamin function to other tocochromanols (including other tocopherols, tocotrienols and eventually tocomonoenols), has not yet been scientifically shown. In fact, the medical prescription of a molecule against the deficiency disease only because it has been included in the "Vitamin E family", but not tested as vitamin E, could lead to ineffective therapy and potentially dangerous consequences for patients. The idea of this revision launched during the recent 3rd Satellite Symposium on Vitamin E of the 2022 SFRR-Europe meeting, offers a open platform of discussion for the scientists involved in vitamin E research and scientific societies interested to this subject.

The modulation of light quality on carotenoid and tocochromanol biosynthesis in mung bean (Vigna radiata) sprouts

This study aimed to identify the regulatory mechanisms of white, blue, red lights on carotenoid and tocochromanol biosynthesis in mung bean sprouts. Results showed that three lights stimulated the increase of the predominated lutein (3.2-8.1 folds) and violaxanthin (2.1-6.1 folds) in sprouts as compared with dark control, as well as β-carotene (20-36 folds), with the best yield observed under white light. Light signals also promoted α- and γ-tocopherol accumulation (up to 1.8 folds) as compared with dark control. The CRTISO, LUT5 and DXS (1.24-6.34 folds) exhibited high expression levels under light quality conditions, resulting in an overaccumulation of carotenoids. The MPBQ-MT, TC and TMT were decisive genes in tocochromanol biosynthesis, and were expressed up to 4.19 folds as compared with control. Overall, the results could provide novel insights into light-mediated regulation and fortification of carotenoids and tocopherols, as well as guide future agricultural cultivation of mung bean sprouts.

Effects of Endogenous Anti-Oxidative Components from Different Vegetable Oils on Their Oxidative Stability

The effects of endogenous anti-oxidative components of ten common edible vegetable oils (palm olein, corn oil, rapeseed oil, soybean oil, perilla seed oil, high oleic sunflower oil, peanut oil, camellia oil, linseed oil, and sesame oil) on oxidation were explored in this research. The oxidation processes and patterns of the oils were investigated with the Schaal oven test using fatty acids and the oxidative stability index, acid value, peroxide value, p-anisidine value, total oxidation value, and content of major endogenous anti-oxidative components as indicators. The major endogenous anti-oxidative components in vegetable oils were tocopherols, sterols, polyphenols, and squalene, among which α-tocopherol, β-sitosterol, and polyphenols showed good anti-oxidative activity. However, squalene and polyphenols were relatively low and showed limited anti-oxidative effects. Moreover, the oxidative stability index of edible vegetable oils oxidized at high temperature (120 °C) was positively correlated with the content of saturated fatty acids (r = 0.659) and negatively correlated with the content of polyunsaturated fatty acids (r = -0.634) and calculated oxidizability (r = -0.696). When oxidized at a low temperature (62 °C), oxidative stability was influenced by a combination of fatty acid composition as well as endogenous anti-oxidative components. An improved TOPSIS based on Mahalanobis distance was used to evaluate the oxidative stability of different types of vegetable oils. Moreover, the oxidative stability of corn oil was better than the other vegetable oils, while perilla seed oil was very weak.

Vitamin E Does Not Disturb Polyunsaturated Fatty Acid Lipid Domains

The function of vitamin E in biomembranes remains a prominent topic of discussion. As its limitations as an antioxidant persist and novel functions are discovered, our understanding of the role of vitamin E becomes increasingly enigmatic. As a group of lipophilic molecules (tocopherols and tocotrienols), vitamin E has been shown to influence the properties of its host membrane, and a wealth of research has connected vitamin E to polyunsaturated fatty acid (PUFA) lipids. Here, we use contrast-matched small-angle neutron scattering and differential scanning calorimetry to integrate these fields by examining the influence of vitamin E on lipid domain stability in PUFA-based lipid mixtures. The influence of α-tocopherol, γ-tocopherol, and α-tocopherylquinone on the lateral organization of a 1:1 lipid mixture of saturated distearoylphosphatidylcholine (DSPC) and polyunsaturated palmitoyl-linoleoylphosphatidylcholine (PLiPC) with cholesterol provides a complement to our growing understanding of the influence of tocopherol on lipid phases. Characterization of domain melting suggests a slight depression in the transition temperature and a decrease in transition cooperativity. Tocopherol concentrations that are an order of magnitude higher than anticipated physiological concentrations (2 mol percent) do not significantly perturb lipid domains; however, addition of 10 mol percent is able to destabilize domains and promote lipid mixing. In contrast to this behavior, increasing concentrations of the oxidized product of α-tocopherol (α-tocopherylquinone) induces a proportional increase in domain stabilization. We speculate how the contrasting effect of the oxidized product may supplement the antioxidant response of vitamin E.

Partial Volumes of Phosphatidylcholines and Vitamin E: α-Tocopherol Prefers Disordered Membranes

Despite its discovery over 95 years ago, the biological and nutritional roles of vitamin E remain subjects of much controversy. Though it is known to possess antioxidant properties, recent assertions have implied that vitamin E may not be limited to this function in living systems. Through densitometry measurements and small-angle X-ray scattering we observe favorable interactions between α-tocopherol and unsaturated phospholipids, with more favorable interactions correlating to an increase in lipid chain unsaturation. Our data provide evidence that vitamin E may preferentially associate with oxygen sensitive lipids─an association that is considered innate for a viable membrane antioxidant.

Hormesis and Oxidative Distress: Pathophysiology of Reactive Oxygen Species and the Open Question of Antioxidant Modulation and Supplementation

Alterations of redox homeostasis leads to a condition of resilience known as hormesis that is due to the activation of redox-sensitive pathways stimulating cell proliferation, growth, differentiation, and angiogenesis. Instead, supraphysiological production of reactive oxygen species (ROS) exceeds antioxidant defence and leads to oxidative distress. This condition induces damage to biomolecules and is responsible or co-responsible for the onset of several chronic pathologies. Thus, a dietary antioxidant supplementation has been proposed in order to prevent aging, cardiovascular and degenerative diseases as well as carcinogenesis. However, this approach has failed to demonstrate efficacy, often leading to harmful side effects, in particular in patients affected by cancer. In this latter case, an approach based on endogenous antioxidant depletion, leading to ROS overproduction, has shown an interesting potential for enhancing susceptibility of patients to anticancer therapies. Therefore, a deep investigation of molecular pathways involved in redox balance is crucial in order to identify new molecular targets useful for the development of more effective therapeutic approaches. The review herein provides an overview of the pathophysiological role of ROS and focuses the attention on positive and negative aspects of antioxidant modulation with the intent to find new insights for a successful clinical application.

The Effect of the Addition of Hemp Seeds, Amaranth, and Golden Flaxseed on the Nutritional Value, Physical, Sensory Characteristics, and Safety of Poultry Pâté

Food producers’ interest in improving the nutritional and pro-health values of meat products has grown. The study aims to assess the effect of replacing poultry pâté products wheat roll (24% group I) in recipes with a mixture of hemp seeds (8% each in groups II, III, IV), amaranth (10% group II, 6% group III, 8% group IV) and golden flaxseed (6% group II, 10% group III, 8% group IV). The quality assessment covered nutritional value, physical properties, the total number of bacteria and assessment of sensory characteristics. The findings indicate that replacing wheat roll with seed mixtures increased the nutritional value (protein, ash, fat, proportion of polyunsaturated and polyene acids) of pâtés in all groups while decreasing the proportion of saturated fatty acids and the ratio of omega-6/omega-3 acids (3:1). This resulted in enhanced brightness and hardness pâtés, as well as greater microbiological safety. Although the spread and firmness of pâtés with seed addition were rated lower than the control, their taste desirability and bonding were rated highest for pâté with 8% plant additives. Pâtés with 24% hemp, amaranth and flaxseed mixture fulfil the requirements to be referred to as functional meat products.

The role of plant-derived natural antioxidants in reduction of oxidative stress

Free radicals are a group of damaging molecules produced during the normal metabolism of cells in the human body. Exposure to ultraviolet radiation, cigarette smoking, and other environmental pollutants enhances free radicals in the human body. The destructive effects of free radicals may also cause harm to membranes, enzymes, and DNA, leading to several human diseases such as cancer, atherosclerosis, malaria, coronavirus disease (COVID-19), rheumatoid arthritis, and neurodegenerative illnesses. This process occurs when there is an imbalance between free radicals and antioxidant defenses. Since antioxidants scavenge free radicals and repair damaged cells, increasing the consumption of fruits and vegetables containing high antioxidant values is recommended to slow down oxidative stress in the body. Additionally, natural products demonstrated a wide range of biological impacts such as anti-inflammatory, anti-aging, anti-atherosclerosis, and anti-cancer properties. Hence, in this review article, our goal is to explore the role of natural therapeutic antioxidant effects to reduce oxidative stress in the diseases.

Dependence of glucose transport on autophagy and GAPDH activity

Glucose uptake in the brain is critically important to brain health. Using two widely used cell line model systems, we have found that siramesine, a lysosomotropic agent and ligand for the sigma-2 receptor, inhibits glucose uptake and decreases pools of the GLUT1 glucose transporter at the plasma membrane. Siramesine induces autophagy but also disrupts degradation of autophagy substrates, providing a potential mechanism for its action on glucose uptake. In other cell systems, many of the effects of siramesine can be suppressed by α -tocopherol, a type of vitamin E and potent antioxidant, and α-tocopherol also suppressed the effect of siramesine on glucose uptake, suggesting a role for reactive oxygen species and membrane maintenance. We have also identified a novel mechanism for siramesine in which it inhibited plasma membrane levels of GAPDH, a key protein in glycolysis which localizes to the plasma membrane in some cell types. Indeed, GAPDH inhibitors decreased glucose uptake, like siramesine, likely through an overlapping pathway with siramesine. GAPDH inhibitors induced autophagy but inhibited degradation of autophagy targets. Thus, we have identified novel mechanisms required for glucose uptake which may have important implications in disease.

Afamin Levels and Their Correlation with Oxidative and Lipid Parameters in Non-diabetic, Obese Patients

Background: Afamin is a liver-produced bioactive protein and features α- and γ-tocopherol binding sites. Afamin levels are elevated in metabolic syndrome and obesity and correlate well with components of metabolic syndrome. Afamin concentrations, correlations between afamin and vitamin E, afamin and lipoprotein subfractions in non-diabetic, obese patients have not been fully examined. Methods: Fifty non-diabetic, morbidly obese patients and thirty-two healthy, normal-weight individuals were involved in our study. The afamin concentrations were measured by ELISA. Lipoprotein subfractions were determined with gel electrophoresis. Gas chromatography–mass spectrometry was used to measure α- and γ tocopherol levels. Results: Afamin concentrations were significantly higher in the obese patients compared to the healthy control (70.4 ± 12.8 vs. 47.6 ± 8.5 μg/mL, p < 0.001). Positive correlations were found between afamin and fasting glucose, HbA1c, hsCRP, triglyceride, and oxidized LDL level, as well as the amount and ratio of small HDL subfractions. Negative correlations were observed between afamin and mean LDL size, as well as the amount and ratio of large HDL subfractions. After multiple regression analysis, HbA1c levels and small HDL turned out to be independent predictors of afamin. Conclusions: Afamin may be involved in the development of obesity-related oxidative stress via the development of insulin resistance and not by affecting α- and γ-tocopherol levels.

Serum vitamin E levels and chronic inflammatory skin diseases: A systematic review and meta-analysis

Background

Vitamin E has long been linked to skin health, including all of its possible functions in cosmetic products, to its roles in membrane integrity and even the aging process. However, reports on the relationship between serum vitamin E levels and the risk of chronic inflammatory skin diseases have been inconsistent. We performed a systematic review and meta-analysis to evaluate the association between serum vitamin E levels and chronic inflammatory skin diseases.

Methods

We searched the PubMed, Web of Science and Scopus databases, with no time limit up to 30.06.2021. Studies examining serum vitamin E levels in patients with chronic inflammatory skin diseases were selected.

Results

Twenty articles met the inclusion criteria. Compared with controls, a lower vitamin E level was found in patients with vitiligo (SMD: -0.70, 95% CI: -1.21 to -0.19), psoriasis (SMD: -2.73, 95% CI: -3.57 to -1.18), atopic dermatitis (SMD: -1.08, 95% CI: -1.80 to -0.36) and acne (SMD: -0.67, 95% CI: -1.05 to -0.30).

Conclusions

Our meta-analysis showed that serum vitamin E levels were lower in patients suffering from vitiligo, psoriasis, atopic dermatitis and acne. This study highlights the need to evaluate vitamin E status to improve its level in patients with skin diseases.

Marine Health-Promoting Compounds: Recent Trends for Their Characterization and Human Applications

Seaweeds represent a rich source of biologically active compounds with several applications, especially in the food, cosmetics, and medical fields. The beneficial effects of marine compounds on health have been increasingly explored, making them an excellent choice for the design of functional foods. When studying marine compounds, several aspects must be considered: extraction, identification and quantification methods, purification steps, and processes to increase their stability. Advanced green techniques have been used to extract these valuable compounds, and chromatographic methods have been developed to identify and quantify them. However, apart from the beneficial effects of seaweeds for human health, these natural sources of bioactive compounds can also accumulate undesirable toxic elements with potential health risks. Applying purification techniques of extracts from seaweeds may mitigate the amount of excessive toxic components, ensuring healthy and safer products for commercialization. Furthermore, limitations such as stability and bioavailability problems, chemical degradation reactions during storage, and sensitivity to oxidation and photo-oxidation, need to be overcome using, for example, nanoencapsulation techniques. Here we summarize recent advances in all steps of marine products identification and purification and highlight selected human applications, including food and feed applications, cosmetic, human health, and fertilizers, among others.