Vitamin E: protective role of a Janus molecule

Antioxidant Therapy as an Effective Strategy against Noise-Induced Hearing Loss: From Experimental Models to Clinic

Cochlear redox unbalance is the main mechanism of damage involved in the pathogenesis of noise-induced-hearing loss. Indeed, the increased free radical production, in conjunction with a reduced efficacy of the endogenous antioxidant system, plays a key role in cochlear damage induced by noise exposure. For this reason, several studies focused on the possibility to use exogenous antioxidant to prevent or attenuate noise-induce injury. Thus, several antioxidant molecules, alone or in combination with other compounds, have been tested in both experimental and clinical settings. In our findings, we tested the protective effects of several antioxidant enzymes, spanning from organic compounds to natural compounds, such as nutraceuticals of polyphenols. In this review, we summarize and discuss the strengths and weaknesses of antioxidant supplementation focusing on polyphenols, Q-Ter, the soluble form of CoQ10, Vitamin E and N-acetil-cysteine, which showed great otoprotective effects in different animal models of noise induced hearing loss and which has been proposed in clinical trials.

Ambient particulate matter (PM10)-induced injury in feline lung cells and nutritional intervention

Ambient particulate matter (APM) is extremely harmful to life's health. In this study, we investigated cellular injury in cat (Felix catus) lung cells (FCA-L2) exposed to organic and water-soluble extracts from APM. As well, the protective effect of vitamin E (VE), lycopene and a mixture of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (molar concentration ratio of 2:1) against this damage was evaluated. Organic and water-soluble extracts induced oxidative stress in FCA-L2 cells, as evidenced by excess reactive oxygen species production and mitochondrial damage, while treatment with VE, lycopene and EPA: DHA remarkably alleviated these indices. It was further found that treatment with EPA: DHA decreased lactate dehydrogenase and malondialdehyde, as well as increased activities of superoxide dismutase, glutathione peroxidase and catalase. Our study confirmed that nutrients mediates APM-induced oxidative stress via antioxidant proteins. Also, these findings could provide new insights into reducing APM-induced cytotoxicity by nutritional supplementation based on antioxidant compounds for animals.

AKF-D52, a Synthetic Phenoxypyrimidine-Urea Derivative, Triggers Extrinsic/Intrinsic Apoptosis and Cytoprotective Autophagy in Human Non-Small Cell Lung Cancer Cells

Simple Summary

We previously reported the antiproliferative effects of a phenoxypyridine urea derivative. In this study, we aimed to investigate the antiproliferative effects of 1-(3,5-dimethoxyphenyl)-3-(4-(3-methoxyphenoxy)-2-((4-morpholinophenyl)amino)pyrimidin-5-yl)urea (AKF-D52) in non-small cell lung cancer cells. We found that (i) AKF-D52 induces apoptosis in caspase-dependent and caspase-independent pathways; (ii) AKF-D52-induced apoptosis is caused by the clustering of a death-inducing signaling complex and mitochondrial-dependent signaling; (iii) AKF-D52 induces cytoprotective autophagy, and pre-treatment with an autophagy inhibitor enhances the apoptotic effect of AKF-D52; and (iv) AKF-D52-induced apoptosis and autophagy are attenuated by the reactive oxygen species (ROS) scavenger α-tocopherol. Furthermore, AKF-D52 suppressed tumor growth in a xenograft mouse model. Collectively, our findings regarding the efficacy and molecular mechanisms of AKF-D52 identify this compound as a potential therapeutic agent for the treatment of lung cancer.

Abstract

Previously, we discovered that 1-(3,5-dimethoxyphenyl)-3-(4-(3-methoxyphenoxy)-2-((4-morpholinophenyl)amino)pyrimidin-5-yl)urea (AKF-D52), a synthetic phenoxypyrimidine urea derivative, acts as a growth inhibitor of various cancer cell types. In this study, we elucidated the antiproliferative properties of AFK-D52 and underlying mechanisms in non-small cell lung cancer (NSCLC) cells and an A549 xenograft animal model. AKF-D52 was found to induce both caspase-dependent and -independent apoptotic cell death. Furthermore, the mitochondrial component of the AKF-D52-induced apoptosis mechanism involves a reduction in mitochondrial membrane potential and regulation in B cell lymphoma-2 family protein expression. Moreover, AKF-D52 activates the extrinsic pathway through up-regulated expression of death receptor 3 and Fas and then the formation of a death-inducing signaling complex. AKF-D52 also induced autophagy by increasing acidic vesicular organelle formation and microtubule-associated protein 1A/1B-light chain 3-II levels and reducing p62 levels. Notably, pretreatment with autophagy inhibitors enhanced AKF-D52-induced cell death, indicating that the induced autophagy is cytoprotective. AKF-D52 treatment also triggered reactive oxygen species (ROS) production in NSCLC cells, whereas the antioxidant α-tocopherol abolished AKF-D52-induced cell death. In a xenograft lung cancer mouse model, AKF-D52 administration attenuated tumor growth by inducing apoptosis and autophagy in tumor tissues. Collectively, our data indicate that AKF-D52-induced ROS production plays a role in mediating apoptosis and cytoprotective autophagy in NSCLC.

Oxidized LDLs as Signaling Molecules

Levels of oxidized low-density lipoproteins (oxLDLs) are usually low in vivo but can increase whenever the balance between formation and scavenging of free radicals is impaired. Under normal conditions, uptake and degradation represent the physiological cellular response to oxLDL exposure. The uptake of oxLDLs is mediated by cell surface scavenger receptors that may also act as signaling molecules. Under conditions of atherosclerosis, monocytes/macrophages and vascular smooth muscle cells highly exposed to oxLDLs tend to convert to foam cells due to the intracellular accumulation of lipids. Moreover, the atherogenic process is accelerated by the increased expression of the scavenger receptors CD36, SR-BI, LOX-1, and SRA in response to high levels of oxLDL and oxidized lipids. In some respects, the effects of oxLDLs, involving cell proliferation, inflammation, apoptosis, adhesion, migration, senescence, and gene expression, can be seen as an adaptive response to the rise of free radicals in the vascular system. Unlike highly reactive radicals, circulating oxLDLs may signal to cells at more distant sites and possibly trigger a systemic antioxidant defense, thus elevating the role of oxLDLs to that of signaling molecules with physiological relevance.

α-Tocopherol Stereoisomer Profiles in Matched Human Maternal and Umbilical Cord Plasma

BACKGROUND

α-Tocopherol (αT) is essential for fetal development. One study has shown that the human placenta preferentially transfers the natural stereoisomer, RRR-αT. But prenatal supplements generally contain synthetic αT (S-αT).

OBJECTIVES

We aimed to determine if umbilical cord plasma is enriched for RRR-αT in racially diverse neonates from both uncomplicated and complicated pregnancies and if cord RRR-αT enrichment is impacted by maternal αT stereoisomer profile.

METHODS

We measured αT and αT stereoisomers in plasma from a randomly selected subset of 66 predominantly black and Hispanic maternal-fetal pairs from the Camden Study involving control (n = 28) and complicated pregnancies (n = 38). We collected maternal plasma at study entry (week 16 gestation; w16) and week 28 gestation (w28) and cord plasma at birth.

RESULTS

RRR-αT was the predominant stereoisomer in all maternal and cord plasma samples, but S-αT stereoisomers were found in most samples and comprised a high percentage of αT in some maternal-neonate pairs. Cord plasma had a higher percentage RRR-αT (P < 0.05) and lower percentage S-αT (P < 0.0001) than w28 plasma. Pregnancy status did not impact maternal or cord plasma concentrations of αT, RRR-αT, or S-αT; except plasma from complicated pregnancies was higher in S-αT at w28 than at w16 (P < 0.05). Maternal w28 αT did not correlate with cord αT. However, both maternal w28 αT and S-αT positively correlated with both cord S-αT (r = 0.340, P = 0.0049; r = 0.538, P < 0.00001) and percentage S-αT (r = 0.399, P = 0.001; r = 0.786, P < 0.00001) but negatively correlated with cord percentage RRR-αT (r = -0.399, P = 0.0009; r = -0.786, P < 0.00001).

CONCLUSIONS

The proportion of RRR-αT was higher in cord compared with maternal plasma in both uncomplicated and complicated pregnancies. Our data suggest that maternal S-αT raises cord S-αT and decreases the proportion of RRR-αT in the neonatal circulation. Because the bioactivities of RRR-αT and S-αT differ, this warrants future research to determine the importance of our observations to neonatal αT status.

The protective efficacy of vitamin E and cod liver oil against cisplatin-induced acute kidney injury in rats

Cisplatin (CP) is a highly effective chemotherapeutic agent against neoplasms, but its clinical utility is limited due to the side effects of its dose-dependent nephrotoxicity. Vitamin E (Vit E) and cod liver oil (CLO) are natural substances with chemoprotective effects. The present study was conducted to evaluate the protective effects of Vit E and/or CLO for CP-induced acute kidney injury (AKI) in rats. This study involved 40 mature male Wistar albino rats that were equally allocated into eight groups: Veh, Vit E, CLO, Vit E + CLO, CP, Vit E + CP, CLO + CP, and Vit E + CLO + CP. The co-administration of Vit E and CLO significantly ameliorated CP-induced elevations in serum creatinine (Cr), blood urea nitrogen (BUN), interleukin 1 beta (IL-1β), and interleukin- 6 (IL-6). Further, rats that received Vit E and/or CLO showed significant decrease in malondialdehyde (MDA) and increases in superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) levels in renal tissues, compared to CP-intoxicated rats. Additionally, the treatment restored the normal histological architecture (except for few cast formations) and upregulated the immunostaining area% of aquaporin 3 (AQP3) and downregulated the immunostaining area% of Bcl2 associated X protein (BAX) and inducible nitric oxide synthase (iNOS). The observed effects were stronger in the combination treatment group. The obtained data revealed that Vit E and CLO co-administration protects against the CP-induced AKI more than monotherapy with Vit E or CLO.

Anti-allergic effects of vitamin E in allergic diseases: An updated review

Allergic diseases are caused by the immune system's response to innocent antigens called allergens. Recent decades have seen a significant increase in the prevalence of allergic diseases worldwide, which has imposed various socio-economic effects in different countries. Various factors, including genetic factors, industrialization, improved hygiene, and climate change contribute to the development of allergic diseases in many parts of the world. Moreover, changes in lifestyle and diet habits play pivotal roles in the prevalence of allergic diseases. Dietary changes caused by decreased intake of antioxidants such as vitamin E lead to the generation of oxidative stress, which is central to the development of allergic diseases. It has been reported in many articles that oxidative stress diverts immune responses to the cells associated with the pathogenesis of allergic diseases. The aim of this short review was to summarize current knowledge about the anti-allergic properties of vitamin E.

Cardiovascular and Metabolic Protection by Vitamin E: A Matter of Treatment Strategy?

Cardiovascular diseases (CVD) cause about 1/3 of global deaths. Therefore, new strategies for the prevention and treatment of cardiovascular events are highly sought-after. Vitamin E is known for significant antioxidative and anti-inflammatory properties, and has been studied in the prevention of CVD, supported by findings that vitamin E deficiency is associated with increased risk of cardiovascular events. However, randomized controlled trials in humans reveal conflicting and ultimately disappointing results regarding the reduction of cardiovascular events with vitamin E supplementation. As we discuss in detail, this outcome is strongly affected by study design, cohort selection, co-morbidities, genetic variations, age, and gender. For effective chronic primary and secondary prevention by vitamin E, oxidative and inflammatory status might not have been sufficiently antagonized. In contrast, acute administration of vitamin E may be more translatable into positive clinical outcomes. In patients with myocardial infarction (MI), which is associated with severe oxidative and inflammatory reactions, decreased plasma levels of vitamin E have been found. The offsetting of this acute vitamin E deficiency via short-term treatment in MI has shown promising results, and, thus, acute medication, rather than chronic supplementation, with vitamin E might revitalize vitamin E therapy and even provide positive clinical outcomes.

Cholesterol induced autophagy via IRE1/JNK pathway promotes autophagic cell death in heart tissue

BACKGROUND

Cardiovascular diseases (CVDs), with highest mortality and morbidity rates, are the major cause of death in the world. Due to the limited information on heart tissue changes, mediated by hypercholesterolemia, we planned to investigate molecular mechanisms of endoplasmic reticulum (ER) stress and related cell death in high cholesterol fed rabbit model and possible beneficial effects of α-tocopherol.

METHODS

Molecular changes in rabbit heart tissue and cultured cardiomyocytes (H9c2 cells) were measured by western blotting, qRT-PCR, immunflouresence and flow cytometry experiments. Histological modifications were assessed by light and electron microscopes, while degradation of mitochondria was quantified through confocal microscope.

RESULTS

Feeding rabbits 2% cholesterol diet for 8 weeks and treatment of cultured cardiomyocytes with 10 μg/mL cholesterol for 3 h induced excessive autophagic activity via IRE1/JNK pathway. While no change in ER-associated degradation (ERAD) and apoptotic cell death were determined, electron and confocal microscopy analyses in cholesterol supplemented rabbits revealed significant parameters of autophagic cell death, including cytoplasmic autophagosomes, autolysosomes and organelle loss in juxtanuclear area as well as mitochondria engulfment by autophagosome. Either inhibition of ER stress or JNK in cultured cardiomyocytes or α-tocopherol supplementation in rabbits could counteract the effects of cholesterol.

CONCLUSION

Our findings underline the essential role of hypercholesterolemia in stimulating IRE1/JNK branch of ER stress response which then leads to autophagic cell death in heart tissue. Results also showed α-tocopherol as a promising regulator of autophagic cell death in cardiomyocytes.

Synthesis, DFT Calculations, and In Vitro Antioxidant Study on Novel Carba-Analogs of Vitamin E

Vitamin E is the most active natural lipophilic antioxidant with a broad spectrum of biological activity. α-Tocopherol (α-T), the main representative of the vitamin E family, is a strong inhibitor of lipid peroxidation as a chain-breaking antioxidant. Antioxidant and antiradical properties of vitamin E result from the presence of a phenolic hydroxyl group at the C-6 position. Due to stereoelectronic effects in the dihydropyranyl ring, the dissociation enthalpy for phenolic O–H bond (BDE_OH) is reduced. The high chain-breaking reactivity of α-T is mainly attributed to orbital overlapping of the 2p-type lone pair on the oxygen atom (O1) in para position to the phenolic group, and the aromatic π-electron system. The influence of the O1 atom on the antioxidant activity of vitamin E was estimated quantitatively. The all-rac-1-carba-α-tocopherol was synthesized for the first time. Along with model compounds, 1-carba-analog of Trolox and its methyl ester were screened for their in vitro antioxidant activity by inhibition of styrene oxidation, and for the radical-reducing properties by means of 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) scavenging assay. To study the antioxidant activity, density functional theory (DFT) was also applied. Reaction enthalpies related to HAT (hydrogen atom transfer), SET–PT (sequential electron transfer—proton transfer), and SPLET (sequential proton loss—electron transfer) mechanisms were calculated.

Antioxidants and Atherosclerosis: Mechanistic Aspects

Atherosclerosis is a chronic inflammatory disease which is a major cause of coronary heart disease and stroke in humans. It is characterized by intimal plaques and cholesterol accumulation in arterial walls. The side effects of currently prescribed synthetic drugs and their high cost in the treatment of atherosclerosis has prompted the use of alternative herbal medicines, dietary supplements, and antioxidants associated with fewer adverse effects for the treatment of atherosclerosis. This article aims to present the activity mechanisms of antioxidants on atherosclerosis along with a review of the most prevalent medicinal plants employed against this multifactorial disease. The wide-ranging information in this review article was obtained from scientific databases including PubMed, Web of Science, Scopus, Science Direct and Google Scholar. Natural and synthetic antioxidants have a crucial role in the prevention and treatment of atherosclerosis through different mechanisms. These include: The inhibition of low density lipoprotein (LDL) oxidation, the reduction of reactive oxygen species (ROS) generation, the inhibition of cytokine secretion, the prevention of atherosclerotic plaque formation and platelet aggregation, the preclusion of mononuclear cell infiltration, the improvement of endothelial dysfunction and vasodilation, the augmentation of nitric oxide (NO) bioavailability, the modulation of the expression of adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) on endothelial cells, and the suppression of foam cell formation.

Screening Method for Argan Oil Adulteration with Vegetable Oils: An Online HPLC Assay with Postcolumn Detection Utilizing Chemometric Multidata Analysis

This study is focused on examining the tocopherol isomers (α-, γ-, and δ-) fingerprinting by online RP-HPLC analysis with post column detection using CUPRAC (cupric reducing antioxidant capacity) methodology for argan oil authenticity. The proposed online assay was validated with good precision, reproducibility, and linearity. Sixteen argan oil samples (100% pure-certified and other commercial argan oils), possible adulterating vegetable oils (i.e., olive, sunflower, corn, and soya oils), and virgin argan oil blended with olive, sunflower, corn, and soya oils at levels of 5%, 10%, 15%, and 20% were analyzed. Spectrophotometric CUPRAC, DPPH, and ABTS assays were applied. Discrimination of fraudulent argan oils from virgin samples was performed by utilizing orthogonal partial least-squares discriminant analysis (OPLS-DA) regression modeling with good sensitivity and specificity. We suggested [γ-toc/α-toc] value as a new first screening adulteration factor (AF) that could be used to assess fraudulent argan oil samples. The distinct decrement in AF value was observed by the increase of adulteration rate. The AF values for virgin argan oils were ranged from 11.8 (lower limit) to 18.6 (upper limit). The presence of β-sitosterol detected in commercial argan oils (with AF values out of limit values) was evaluated as fraudulent which was in accordance with the proposed assay. Our method enabled the detection of argan oil samples at adulteration levels of >5% in the case of sunflower, olive, and soya oils, >15% in the case of corn oil. This method may be an alternative and specific assay for the authentication and quality detection of commercial argan oils.

Relationship Between Serum Alpha-Tocopherol and Overall and Cause-Specific Mortality

RATIONALE

Although there has been a long-standing interest in the human health effects of vitamin E, a comprehensive analysis of the association between circulating vitamin E and long-term mortality has not been conducted.

OBJECTIVE

Determine whether serum α-tocopherol (the predominant form of vitamin E) is related to long-term overall and cause-specific mortality and elucidate the dose-response relationships with better quantification of the associations.

METHODS AND RESULTS

We conducted a biochemical analysis of 29 092 participants in the ATBC Study (Alpha-Tocopherol, Beta-Carotene Cancer Prevention) that originally tested vitamin E and β-carotene supplementation. Serum α-tocopherol was measured at baseline using high-performance liquid chromatography, and during a 30-year follow-up we identified 23 787 deaths, including deaths from cardiovascular disease (9867), cancer (7687), respiratory disease (2161), diabetes mellitus (119), injuries and accidents (1255), and other causes (2698). After adjusting for major risk factors, we found that men with higher serum α-tocopherol had significantly lower all-cause mortality (hazard ratios=0.83, 0.79, 0.75, and 0.78 for quintile 2 (Q2)-Q5 versus Q1, respectively; P_trend<0.0001), and significantly decreased mortality from cardiovascular disease, heart disease, stroke, cancer, respiratory disease, and other causes, with risk reductions from 17% to 47% for the highest versus lowest quintile. The α-tocopherol association with overall mortality was similar across subgroups of smoking intensity, years of smoking, alcohol consumption, trial supplementation, and duration of follow-up. The association was, however, significantly modified by baseline age and body mass index, with stronger inverse associations for younger men and men with a lower body mass index ( P_interaction≤0.006).

CONCLUSIONS

In this long-term prospective cohort study, higher baseline serum α-tocopherol biochemical status was associated with lower risk of overall mortality and mortality from all major causes. Our data support the long-term health benefits of higher serum α-tocopherol for overall and chronic disease mortality and should be replicated in other more diverse populations.

Interaction Effects of Plasma Vitamins A, E, D, B9, and B12 and Tobacco Exposure in Urothelial Bladder Cancer: A Multifactor Dimensionality Reduction Analysis

The study aimed to examine circulating vitamins A, E, D, and B12 and folate in patients with urothelial bladder cancer (UBC) and detect potential interaction effects of these micronutrients on UBC risk. A case-control study was conducted on 262 UBC patients and 254 matched controls. Vitamins A and E were assessed by ultra performance liquid chromatography, and vitamins D and B12 and folate were assessed by immunological methods. Binary logistic regression models were used to test associations of plasma vitamins tertiles with UBC risk. A multifactor dimensionality reduction method (MDR) was applied to assess interactive effects of the vitamins and tobacco on UBC risk. Higher levels in vitamins A, E, and D were associated with lower occurrence of UBC. No significant association was observed in plasma folate or vitamin B12 with UBC. There were redundancy interactions of plasma vitamin D with tobacco and with plasma vitamin A on UBC risk. Even though the study could not ascertain causality, the findings suggest that vitamins A, E, and D might be protective against UBC. Vitamins A and D interact antagonistically with each other's and with tobacco to modulate UBC risk. These interactions should be taken in consideration for the prevention of UBC.

Vitamin E: Regulatory Role on Signal Transduction

Vitamin E modulates signal transduction pathways by several molecular mechanisms. As a hydrophobic molecule located mainly in membranes it contributes together with other lipids to the physical and structural characteristics such as membrane stability, curvature, fluidity, and the organization into microdomains (lipid rafts). By acting as the main lipid-soluble antioxidant, it protects other lipids such as mono- and poly-unsaturated fatty acids (MUFA and PUFA, respectively) against chemical reactions with reactive oxygen and nitrogen species (ROS and RNS, respectively) and prevents membrane destabilization and cellular dysfunction. In cells, vitamin E affects signaling in redox-dependent and redox-independent molecular mechanisms by influencing the activity of enzymes and receptors involved in modulating specific signal transduction and gene expression pathways. By protecting and preventing depletion of MUFA and PUFA it indirectly enables regulatory effects that are mediated by the numerous lipid mediators derived from these lipids. In recent years, some vitamin E metabolites have been observed to affect signal transduction and gene expression and their relevance for the regulatory function of vitamin E is beginning to be elucidated. In particular, the modulation of the CD36/FAT scavenger receptor/fatty acids transporter by vitamin E may influence many cellular signaling pathways relevant for lipid homeostasis, inflammation, survival/apoptosis, angiogenesis, tumorigenesis, neurodegeneration, and senescence. Thus, vitamin E has an important role in modulating signal transduction and gene expression pathways relevant for its uptake, distribution, metabolism, and molecular action that when impaired affect physiological and patho-physiological cellular functions relevant for the prevention of a number of diseases. © 2018 IUBMB Life, 71(4):456-478, 2019.

Oxidative stress and neurodegeneration: the involvement of iron

Many evidences indicate that oxidative stress plays a significant role in a variety of human disease states, including neurodegenerative diseases. Iron is an essential metal for almost all living organisms due to its involvement in a large number of iron-containing proteins and enzymes, though it could be also toxic. Actually, free iron excess generates oxidative stress, particularly in brain, where anti-oxidative defences are relatively low. Its accumulation in specific regions is associated with pathogenesis in a variety of neurodegenerative diseases (i.e., Parkinson's disease, Alzheimer's disease, Huntington's chorea, Amyotrophic Lateral Sclerosis and Neurodegeneration with Brain Iron Accumulation). Anyway, the extent of toxicity is dictated, in part, by the localization of the iron complex within the cell (cytosolic, lysosomal and mitochondrial), its biochemical form, i.e., ferritin or hemosiderin, as well as the ability of the cell to prevent the generation and propagation of free radical by the wide range of antioxidants and cytoprotective enzymes in the cell. Particularly, ferrous iron can act as a catalyst in the Fenton reaction that potentiates oxygen toxicity by generating a wide range of free radical species, including hydroxyl radicals (·OH). The observation that patients with neurodegenerative diseases show a dramatic increase in their brain iron content, correlated with the production of reactive oxigen species in these areas of the brain, conceivably suggests that disturbances in brain iron homeostasis may contribute to the pathogenesis of these disorders. The aim of this review is to describe the chemical features of iron in human beings and iron induced toxicity in neurodegenerative diseases. Furthermore, the attention is focused on metal chelating drugs therapeutic strategies.

Corosolic Acid Induces Non-Apoptotic Cell Death through Generation of Lipid Reactive Oxygen Species Production in Human Renal Carcinoma Caki Cells

Corosolic acid is one of the pentacyclic triterpenoids isolated from Lagerstroemia speciose and has been reported to exhibit anti-cancer and anti-proliferative activities in various cancer cells. In the present study, we investigated the molecular mechanisms of corosolic acid in cancer cell death. Corosolic acid induces a decrease of cell viability and an increase of cell cytotoxicity in human renal carcinoma Caki cells. Corosolic acid-induced cell death is not inhibited by apoptosis inhibitor (z-VAD-fmk, a pan-caspase inhibitor), necroptosis inhibitor (necrostatin-1), or ferroptosis inhibitors (ferrostatin-1 and deferoxamine (DFO)). Furthermore, corosolic acid significantly induces reactive oxygen species (ROS) levels, but antioxidants (N-acetyl-l-cysteine (NAC) and trolox) do not inhibit corosolic acid-induced cell death. Interestingly, corosolic acid induces lipid oxidation, and α-tocopherol markedly prevents corosolic acid-induced lipid peroxidation and cell death. Anti-chemotherapeutic effects of α-tocopherol are dependent on inhibition of lipid oxidation rather than inhibition of ROS production. In addition, corosolic acid induces non-apoptotic cell death in other renal cancer (ACHN and A498), breast cancer (MDA-MB231), and hepatocellular carcinoma (SK-Hep1 and Huh7) cells, and α-tocopherol markedly inhibits corosolic acid-induced cell death. Therefore, our results suggest that corosolic acid induces non-apoptotic cell death in cancer cells through the increase of lipid peroxidation.

Cyclodextrins increase phytosterol and tocopherol levels in suspension cultured cells obtained from mung beans and safflower

In this work, suspension-cultured cells of mung beans and safflower were used in order to analyze the effect of methyl jasmonate and/or cyclodextrins, on bioactive compound production such as phytosterols and tocopherols. The results indicated that mung bean suspension-cultured cells produced higher amount of total phytosterols and tocopherols. In particular, mung bean suspension-cultured cells produced almost 220-fold higher levels of tocopherols than safflower suspension-cultured cells in the best conditions. However, while cyclodextrins were able to enhance extracellular production of phytosterols, in the case of tocopherols, they only increased their intracellular accumulation. Our results showed that mung bean cells could be used as a highly efficient system for the production of phytosterols and tocopherols which have a wide range of biological activities. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1662-1665, 2017.

Vitamins, metabolomics, and prostate cancer

PURPOSE

How micronutrients might influence risk of developing adenocarcinoma of the prostate has been the focus of a large body of research (especially regarding vitamins E, A, and D). Metabolomic profiling has the potential to discover molecular species relevant to prostate cancer etiology, early detection, and prevention, and may help elucidate the biologic mechanisms through which vitamins influence prostate cancer risk.

METHODS

Prostate cancer risk data related to vitamins E, A, and D and metabolomic profiling from clinical, cohort, and nested case-control studies, along with randomized controlled trials, are examined and summarized, along with recent metabolomic data of the vitamin phenotypes.

RESULTS

Higher vitamin E serologic status is associated with lower prostate cancer risk, and vitamin E genetic variant data support this. By contrast, controlled vitamin E supplementation trials have had mixed results based on differing designs and dosages. Beta-carotene supplementation (in smokers) and higher circulating retinol and 25-hydroxy-vitamin D concentrations appear related to elevated prostate cancer risk. Our prospective metabolomic profiling of fasting serum collected 1-20 years prior to clinical diagnoses found reduced lipid and energy/TCA cycle metabolites, including inositol-1-phosphate, lysolipids, alpha-ketoglutarate, and citrate, significantly associated with lower risk of aggressive disease.

CONCLUSIONS

Several active leads exist regarding the role of micronutrients and metabolites in prostate cancer carcinogenesis and risk. How vitamins D and A may adversely impact risk, and whether low-dose vitamin E supplementation remains a viable preventive approach, require further study.

Subchronic Oral Toxicity Study of Mixed Tocopheryl Phosphates in Rats

Rats were fed diets containing 0%, 1 %, 3%, or 5% mixed tocopheryl phosphates for 90 days. No abnormal clinical signs related to treatment appeared. Some statistically significant changes in hematology and clinical chemistry parameters appeared, but the majority were not dose dependent, occurred in only one sex or group, and/or remained within the historical control range for this strain of rat. A statistically significant apparent reduction in blood protein was observed in animals treated with the tocopheryl phosphates, but further investigation showed that the test substance interfered with the protein assay. Repeat analysis using a method unaffected by plasma test substance levels showed no difference in plasma proteins among all groups. Gross necropsy revealed no abnormalities; reduced relative heart and epididymal weights were observed, but were not dose dependent and were considered incidental. Histopathological changes occurred only in the mesenteric lymph node and small intestine. Foreign material in a crystal-like form appeared in macrophages in both organs, and increased in a dose-related fashion. In the lymph node, sinus histiocytosis increased with dose, but the severity was similar between the control and low-dose groups. Foreign-body granulomatous inflammation, associated with Maltese cross birefringence of the crystals was seen in the mid- and high-dose animals, but not the low-dose group. Similarly, the small intestine showed increasing amounts of foreign material and inflammation in the mid- and high-dose but not in the 1 % diet. The 1 % diet (equivalent to 587 and 643 mg mixed tocopheryl phosphates/kg body weight/day for male and female rats, respectively) was considered the no observed adverse effect level.

Role of Endogenous and Exogenous Tocopherols in the Lipid Stability of Marine Oil Systems: A Review

In marine organisms primarily intended for human consumption, the quality of the muscle and the extracted oils may be affected by lipid oxidation during storage, even at low temperatures. This has led to a search for alternatives to maintain quality. In this sense, antioxidant compounds have been used to prevent such lipid deterioration. Among the most used compounds are tocopherols, which, due to their natural origin, have become an excellent alternative to prevent or retard lipid oxidation and maintain the quality of marine products. Tocopherols as antioxidants have been studied both exogenously and endogenously. Exogenous tocopherols are often used by incorporating them into plastic packaging films or adding them directly to fish oil. It has been observed that exogenous tocopherols incorporated in low concentrations maintain the quality of both muscle and the extracted oils during food storage. However, it has been reported that tocopherols applied at higher concentrations act as a prooxidant molecule, probably because their reactions with singlet oxygen may generate free radicals and cause the oxidation of polyunsaturated fatty acids in fish oils. However, when tocopherols are included in a fish diet (endogenous tocopherols), the antioxidant effect on the muscle lipids is more effective due to their incorporation into the membrane lipids, which can help extend the shelf life of seafood by reducing the lipid deterioration that occurs due to antioxidant synergy with other phenolic compounds used supplements in fish muscle. This review focuses on the most important studies in this field and highlights the potential of using tocopherols as antioxidants in marine oils.

Antioxidant and Hepatoprotective Activity of a New Tablets Formulation from Tamarindus indica L

Hepatotoxic chemicals damage liver cells primarily by producing reactive oxygen species. The decoction of the leaves of Tamarindus indica L. is used for liver disorders. In this work we evaluated the hepatoprotective activity of a tablet formulation of this plant. Thirty-five Sprague Dawley rats were randomly divided into five groups (n = 7). First group (I) is control group, fed with standard diet. Groups II to V (hepatotoxic groups) were subjected to a subcutaneous injection of CCl4 (0.5 mL/kg). Group II was negative control, fed with standard diet; group III was subjected to administration of Silymarin 150 mg/kg and groups IV and V were treated with tablets in dose of 100 mg/kg and 200 mg/kg, respectively. Lipid peroxidation and the activity of superoxide dismutase, catalase, and reduced glutathione were evaluated. Serum levels of alanine aminotransferase, aspartate aminotransferase, gamma-glutamine transferase, alkaline phosphatase, and a lipid profile were evaluated too. The tablets inhibit lipid peroxidation. The redox balance (SOD-CAT-GSH) remains normal in the experimental groups treated with tablets. The liver function using dose of 200 mg/kg of tablets was better than the other experimental groups. These results justify, scientifically, the ethnobotanical use of the leaves of Tamarindus indica L.

A Plasma α-Tocopherome Can Be Identified from Proteins Associated with Vitamin E Status in School-Aged Children of Nepal

BACKGROUND

The term vitamin E describes a family of 8 vitamers, 1 of which is α-tocopherol, that is essential for human health. Vitamin E status remains largely unknown in low-income countries because of the complexity and cost of measurement. Quantitative proteomics may offer an approach for identifying plasma proteins for assessing vitamin E status in these populations.

OBJECTIVE

To improve options for vitamin E status assessment, we sought to detect and quantify a set of plasma proteins associated with α- and γ-tocopherol concentrations in a cohort of 500 rural Nepalese children aged 6-8 y and, based on nutrient-protein associations, to predict the prevalence of vitamin E deficiency (α-tocopherol <12 μmol/L).

METHODS

Study children were born to mothers enrolled in an earlier antenatal micronutrient trial in Sarlahi District, Nepal. Plasma α- and γ-tocopherol concentrations were measured by high-performance liquid chromatography. Plasma aliquots were depleted of 6 high-abundance proteins, digested with trypsin, labeled with isobaric mass tags, and assessed for relative protein abundance by tandem mass spectrometry. Linear mixed-effects models were used to evaluate the association between α-tocopherol status and relative protein abundance and to predict deficiency.

RESULTS

We quantified 982 plasma proteins in >10% of all child samples, of which 119 correlated with α-tocopherol (false discovery rate, q < 0.10). Proteins were primarily involved in lipid transport, coagulation, repair, innate host defenses, neural function, and homeostasis. Six proteins [apolipoprotein (apo)C-III; apoB; pyruvate kinase, muscle; forkhead box 04; unc5 homolog C; and regulator of G-protein signaling 8] explained 71% of the variability in plasma α-tocopherol, predicting an in-sample population prevalence of vitamin E deficiency of 51.4% (95% CI: 46.4%, 56.3%) compared with a measured prevalence of 54.8%. Plasma γ-tocopherol was associated with 12 proteins (q < 0.10), 2 of which (apoC-III and Misato 1) explained 20% of its variability.

CONCLUSIONS

In this undernourished population of children in South Asia, quantitative proteomics identified a large plasma α-tocopherome from which 6 proteins predicted the prevalence of vitamin E deficiency. The findings illustrate that protein biomarkers, once absolutely quantified, can potentially predict micronutrient deficiencies in populations. The maternal micronutrient supplementation trial from which data were derived as a follow-up activity was registered with clinicaltrials.gov as NCT00115271.

Structural re-arrangement and peroxidase activation of cytochrome c by anionic analogues of vitamin E, tocopherol succinate and tocopherol phosphate

Cytochrome c is a multifunctional hemoprotein in the mitochondrial intermembrane space whereby its participation in electron shuttling between respiratory complexes III and IV is alternative to its role in apoptosis as a peroxidase activated by interaction with cardiolipin (CL), and resulting in selective CL peroxidation. The switch from electron transfer to peroxidase function requires partial unfolding of the protein upon binding of CL, whose specific features combine negative charges of the two phosphate groups with four hydrophobic fatty acid residues. Assuming that other endogenous small molecule ligands with a hydrophobic chain and a negatively charged functionality may activate cytochrome c into a peroxidase, we investigated two hydrophobic anionic analogues of vitamin E, α-tocopherol succinate (α-TOS) and α-tocopherol phosphate (α-TOP), as potential inducers of peroxidase activity of cytochrome c. NMR studies and computational modeling indicate that they interact with cytochrome c at similar sites previously proposed for CL. Absorption spectroscopy showed that both analogues effectively disrupt the Fe-S(Met(80)) bond associated with unfolding of cytochrome c. We found that α-TOS and α-TOP stimulate peroxidase activity of cytochrome c. Enhanced peroxidase activity was also observed in isolated rat liver mitochondria incubated with α-TOS and tBOOH. A mitochondria-targeted derivative of TOS, triphenylphosphonium-TOS (mito-VES), was more efficient in inducing H2O2-dependent apoptosis in mouse embryonic cytochrome c(+/+) cells than in cytochrome c(-/-) cells. Essential for execution of the apoptotic program peroxidase activation of cytochrome c by α-TOS may contribute to its known anti-cancer pharmacological activity.

Histological and histometrical study of the protective role of α-tocopherol against sodium arsenite toxicity in rat ovaries

This study examines histometrical changes induced by sodium arsenite (SA), as an environmental pollutant, and investigates the protective effect of α-tocopherol on ovaries of SA-treated rats during the prenatal stage until sexual maturity. Rats were classified into groups: control, SA (8 ppm/day), α-tocopherol (100 ppm/day), and SA+α-tocopherol. Treatment was performed from pregnancy until maturation when the rats and ovaries were weighed. The Cavalieri method was used to estimate volume of the ovaries, cortex, medulla, and corpus luteum. The mean diameter of oocytes, granulosa cells, and nuclei were measured and volume was estimated using the Nucleator method. The number of oocytes and thickness of the zona pellucida (ZP) were determined using an optical dissector and orthogonal intercept method, respectively. SA reduced the body and ovary weight, the number of secondary, antral and Graafian oocytes, volume of the ovaries, cortex, medulla and corpus luteum, mean diameter and volume of oocytes in primordial and primary follicles, mean diameter and volume of oocyte nuclei in all types of follicles, and mean thickness of the ZP in secondary and antral follicles. Also, the mean diameter and volume of granulosa cells and their nuclei in antral and Graafian follicles decreased significantly. Vacuolization and vascular congestion in the corpus luteum and an increase in the number of atretic oocytes were seen in the SA group. Most of these parameters were unchanged from the control level in the SA+α-tocopherol group. It was concluded that α-tocopherol supplementation reduced the toxic effects of SA exposure on ovarian tissue in rats.

Plasma tocopherols and risk of prostate cancer in the Selenium and Vitamin E Cancer Prevention Trial (SELECT)

The Selenium and Vitamin E Cancer Prevention Trial (SELECT) showed higher prostate cancer incidence in men supplemented with high-dose α-tocopherol. We, therefore, examined whether presupplementation plasma α-tocopherol or γ-tocopherol was associated with overall or high-grade prostate cancer. A stratified case-cohort sample that included 1,746 incident prostate cancer cases diagnosed through June 2009 and a subcohort of 3,211 men was derived from the SELECT trial of 35,533 men. Plasma was collected at entry from 2001 to 2004, and median follow-up was 5.5 years (range, 0-7.9 years). Incidence of prostate cancer as a function of plasma α-tocopherol, γ-tocopherol, and supplementation with α-tocopherol or selenomethionine was estimated by the hazard ratio (HR). Plasma γ-tocopherol was not associated with prostate cancer. Men with higher α-tocopherol concentrations seemed to have risk similar to that of men with lower concentrations [overall HR for fifth (Q5) vs. first quintile (Q1), 1.21; 95 % confidence interval (CI), 0.88-1.66; P-trend = 0.24; in the trial placebo arm, Q5 HR, 0.85; 95% CI, 0.44-1.62; P-trend = 0.66]. We found a strong positive plasma α-tocopherol association among men receiving the trial selenomethionine supplement [Q5 HR, 2.04; 95% CI, 1.29-3.22; P-trend = 0.005]. A positive plasma α-tocopherol-prostate cancer association also seemed limited to high-grade disease (Gleason grade, 7-10; overall Q5 HR, 1.59; 95% CI, 1.13-2.24; P-trend = 0.001; among men receiving selenomethionine, Q5 HR, 2.12; 95% CI, 1.32-3.40; P-trend = 0.0002). Our findings indicate that higher plasma α-tocopherol concentrations may interact with selenomethionine supplements to increase high-grade prostate cancer risk, suggesting a biologic interaction between α-tocopherol and selenium itself or selenomethionine.

Antioxidant intervention attenuates oxidative stress in children and teenagers with Down syndrome

We previously demonstrated that systemic oxidative stress is present in Down syndrome (DS) patients. In the present study we investigated the antioxidant status in the peripheral blood of DS children and teenagers comparing such status before and after an antioxidant supplementation. Oxidative stress biomarkers were evaluated in the blood of DS patients (n=21) before and after a daily antioxidant intervention (vitamin E 400mg, C 500 mg) during 6 months. Healthy children (n=18) without DS were recruited as control group. The activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), gamma-glutamyltransferase (GGT), glucose-6-phosphate dehydrogenase (G6PD) and myeloperoxidase (MPO), as well as the contents of reduced glutathione (GSH), uric acid, vitamin E, thiobarbituric acid reactive substances (TBARS), and protein carbonyls (PC) were measured. Before the antioxidant therapy, DS patients presented decreased GST activity and GSH depletion; elevated SOD, CAT, GR, GGT and MPO activities; increased uric acid levels; while GPx and G6PD activities as well as vitamin E and TBARS levels were unaltered. After the antioxidant supplementation, SOD, CAT, GPx, GR, GGT and MPO activities were downregulated, while TBARS contents were strongly decreased in DS. Also, the antioxidant therapy did not change G6PD and GST activities as well as uric acid and PC levels, while it significantly increased GSH and vitamin E levels in DS patients. Our results clearly demonstrate that the antioxidant intervention with vitamins E and C attenuated the systemic oxidative damage present in DS patients.

Dietary vitamin E affects α-TTP mRNA levels in different tissues of the Tan sheep

The α-tocopherol transfer protein (α-TTP) is a ~32kDa cytosolic protein that plays an important role in the efficient circulation of plasma α-tocopherol in the body, a factor with great relevance in reproduction. The α-TTP gene has been studied in a number of tissues; however, its expression and function in some ovine tissues remain unclear. A previous study from our laboratory has demonstrated α-TTP expression in sheep liver. In the present study we determined whether α-TTP is expressed in non-liver tissues and investigated the effects of dietary vitamin E on the α-TTP mRNA levels. Thirty-five male Tan sheep with similar body weight were randomly allocated into five groups and supplemented 0, 20, 100, 200 and 2000IUsheep(-1)day(-1) vitamin E, for four months, respectively. At the end of the study, the animals were slaughtered and tissue samples from the heart, spleen, lung, kidney, longissimus dorsi muscle and gluteus muscle were immediately collected. We found that the α-TTP gene is expressed in sheep tissues other than the liver. Moreover, dietary vitamin E levels had influenced the expression levels of α-TTP gene in these tissues in a tissue-specific way. The technique of immunohistochemistry was used to detect α-TTP in tissues of the heart, spleen, lung, and kidney and we found that α-TTP was mainly located in the cytoplasm while no α-TTP immunoreactivity was detected in the cytoplasm of longissimus dorsi and gluteus muscle samples. Importantly, our findings lay the foundation for additional experiments focusing on the absorption and metabolism of vitamin E in tissues other than the liver.

Antioxidants delay clinical signs and systemic effects of ENU induced brain tumors in rats

According to our previous study suggesting that antioxidant properties of phytochemicals in the diet decrease glioma aggressiveness, we used a SUVIMAX-like diet ("Supplementation en VItamines et Minéraux AntioXydants") (enriched with alpha-tocopherol, beta carotene, vitamin C, zinc, and sodium selenite), adapted to rats. The present results showed that each of the antioxidants inhibited growth of glioma cells in vitro. When used in combination for in vivo studies, we showed a highly significant delay in the clinical signs of the disease, but not a statistical significant difference in the incidence of glioma in an Ethyl-nitrosourea (ENU)-model. The SUVIMAX-like diet decreased candidate markers of tumoral aggressiveness and gliomagenesis progression. The mRNA expressions of 2 common markers in human glioma: Mn-SOD (Manganese Superoxide Dismutase) and IGFBP5 (insulin growth factor binding protein) were reduced in the tumors of rats fed the antioxidant diet. In addition, the transcripts of two markers linked to brain tumor proliferation, PDGFRb (platelet-derived growth factor receptor beta) and Ki-67, were also significantly decreased. On the whole, our results suggest a protective role for antioxidants to limit aggressiveness and to some extent, progression of gliomas, in a rat model.

Potential role of carotenoids as antioxidants in human health and disease

Carotenoids constitute a ubiquitous group of isoprenoid pigments. They are very efficient physical quenchers of singlet oxygen and scavengers of other reactive oxygen species. Carotenoids can also act as chemical quenchers undergoing irreversible oxygenation. The molecular mechanisms underlying these reactions are still not fully understood, especially in the context of the anti- and pro-oxidant activity of carotenoids, which, although not synthesized by humans and animals, are also present in their blood and tissues, contributing to a number of biochemical processes. The antioxidant potential of carotenoids is of particular significance to human health, due to the fact that losing antioxidant-reactive oxygen species balance results in “oxidative stress”, a critical factor of the pathogenic processes of various chronic disorders. Data coming from epidemiological studies and clinical trials strongly support the observation that adequate carotenoid supplementation may significantly reduce the risk of several disorders mediated by reactive oxygen species. Here, we would like to highlight the beneficial (protective) effects of dietary carotenoid intake in exemplary widespread modern civilization diseases, i.e., cancer, cardiovascular or photosensitivity disorders, in the context of carotenoids’ unique antioxidative properties.

In vitro effect of sodium fluoride on malondialdehyde concentration and on superoxide dismutase, catalase, and glutathione peroxidase in human erythrocytes

The aim of this paper was to describe the in vitro effect of sodium fluoride (NaF) on the specific activity of the major erythrocyte antioxidant enzymes, as well as on the membrane malondialdehyde concentration, as indicators of oxidative stress. For this purpose, human erythrocytes were incubated with NaF (0, 7, 28, 56, and 100 μg/mL) or NaF (100 μg/mL) + vitamin E (1, 2.5, 5 and 10 μg/mL). The malondialdehyde (MDA) concentration on the surface of the erythrocytes was determined, as were the enzymatic activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GlPx). Our results demonstrated that erythrocytes incubated with increasing NaF concentrations had an increased MDA concentration, along with decreased activity of antioxidant enzymes. The presence of vitamin E partially reversed the toxic effects of NaF on erythrocytes. These findings suggest that NaF induces oxidative stress in erythrocytes in vitro, and this stress is partially reversed by the presence of vitamin E.

Biosynthesis, structural, and functional attributes of tocopherols in planta; past, present, and future perspectives

Tocopherols are lipophilic molecules, ubiquitously synthesized in all photosynthetic organisms. Being a group of vitamin E compounds, they play an essential role in human nutrition and health. Despite their structural and functional attributes as important antioxidants in plants, it would be misleading to ignore the potential roles of tocopherols beyond their antioxidant properties in planta. Detailed characterization of mutants and transgenic plants, including Arabidopsis (vte1, vte2, vte4, and so on), maize (sxd1) mutants, and transgenic potato and tobacco lines altered in tocopherol biosynthesis and contents, has led to surprising outcomes regarding the additional functions of these molecules. Thus, the aim of this review is to highlight the past and present research findings on tocopherols' structural, biosynthesis, and functional properties in plants. Special emphasis is given to their suggested functions in planta, such as cell signaling, hormonal interactions, and coordinated response of tocopherols to other antioxidants under abiotic stresses. Moreover, some important questions about possible new functions of tocopherols will be discussed as future prospects to stimulate further research.

Vitamin E serum levels and controlled supplementation and risk of amyotrophic lateral sclerosis

There are no observational studies or controlled trials of amyotrophic lateral sclerosis (ALS) and circulating α-tocopherol (vitamin E) for prevention of ALS. This study addresses that gap. The study population comprised 29,127 Finnish male smokers, aged 50-69 years, who participated in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study, which is both a prospective cohort and a randomized, double-blind, placebo-controlled trial of α-tocopherol (50 mg/day) and β-carotene (20 mg/day). Serum α-tocopherol and β-carotene was assayed at baseline (1985 - 1988). Follow-up (median 16.7 years) continued through 2004. ALS cases were identified through the national Hospital Discharge Register with diagnostic verification by hospital records and death certificates. During 407,260 person-years of follow-up, 50 men were identified with ALS. For males with serum α-tocopherol concentration above the median (≥ 11.6 mg/l), the age-adjusted relative risk (RR) compared to α-tocopherol below the median, was 0.56 (95% confidence interval 0.32 - 0.99), p = 0.046. The RR among α-tocopherol supplement recipients was 0.75 (95% CI 0.32 - 1.79), p = 0.52. Neither serum β-carotene level nor β-carotene supplementation was associated with ALS. In conclusion, the results are consistent with a hypothesized protective effect of α-tocopherol on ALS risk. However, pooled analyses of cohorts with serum and controlled trials are needed to clarify the role of α-tocopherol in ALS risk.

Antioxidant supplementation reduces endometriosis-related pelvic pain in humans

We previously suggested that women with endometriosis have increased oxidative stress in the peritoneal cavity. To assess whether antioxidant supplementation would ameliorate endometriosis-associated symptoms, we performed a randomized, placebo-controlled trial of antioxidant vitamins (vitamins E and C) in women with pelvic pain and endometriosis. Fifty-nine women, ages 19 to 41 years, with pelvic pain and history of endometriosis or infertility were recruited for this study. Patients were randomly assigned to 2 groups: vitamin E (1200 IU) and vitamin C (1000 mg) combination or placebo daily for 8 weeks before surgery. Pain scales were administered at baseline and biweekly. Inflammatory markers were measured in the peritoneal fluid obtained from both groups of patients at the end of therapy. Our results indicated that after treatment with antioxidants, chronic pain ("everyday pain") improved in 43% of patients in the antioxidant treatment group (P = 0.0055) compared with the placebo group. In the same group, dysmenorrhea ("pain associated with menstruation") and dyspareunia ("pain with sex") decreased in 37% and 24% patients, respectively. In the placebo group, dysmenorrhea-associated pain decreased in 4 patients and no change was seen in chronic pain or dyspareunia. There was a significant decrease in peritoneal fluid inflammatory markers, regulated upon activation, normal T-cell expressed and secreted (P ≤ 0.002), interleukin-6 (P ≤ 0.056), and monocyte chemotactic protein-1 (P ≤ 0.016) after antioxidant therapy compared with patients not taking antioxidants. The results of this clinical trial show that administration of antioxidants reduces chronic pelvic pain in women with endometriosis and inflammatory markers in the peritoneal fluid.

Effects of vitamin e on bone biomechanical and histomorphometric parameters in ovariectomized rats

The present study examined the dose-dependent effect of vitamin E in reversing bone loss in ovariectomized (Ovx) rats. Sprague-Dawley rats were either Sham-operated (Sham) or Ovx and fed control diet for 120 days to lose bone. Subsequently, rats were divided into 5 groups (n = 12/group): Sham, Ovx-control, low dose (Ovx + 300 mg/kg diet; LD), medium dose (Ovx + 525 mg/kg diet; MD), and high dose (Ovx + 750 mg/kg diet; HD) of vitamin E and sacrificed after 100 days. Animals receiving MD and HD of vitamin E had increased serum alkaline phosphatase compared to the Ovx-control group. Bone histomorphometry analysis indicated a decrease in bone resorption as well as increased bone formation and mineralization in the Ovx groups supplemented with MD and HD of vitamin E. Microcomputed tomography findings indicated no effects of vitamin E on trabecular bone of fifth lumbar vertebrae. Animals receiving HD of vitamin E had enhanced fourth lumbar vertebra quality as evidenced by improved ultimate and yield load and stress when compared to Ovx-control group. These findings demonstrate that vitamin E improves bone quality, attenuates bone resorption, and enhances the rate of bone formation while being unable to restore bone density and trabecular bone structure.

Vitamin e and bone structural changes: an evidence-based review

Purpose. This paper explores the effects of vitamin E on bone structural changes. Methods. A systematic review of the literature was conducted to identify relevant studies about vitamin E and osteoporosis/bone structural changes. A comprehensive search in Medline and CINAHL for relevant studies published between the years 1946 and 2012 was conducted. The main inclusion criteria were published in English, studies had to report the association or effect of vitamin E and osteoporosis-related bone changes, and the osteoporosis-related bone changes should be related to lifestyle variables, aging, or experimentally-induced conditions. Results. The literature search identified 561 potentially relevant articles, whereby 11 studies met the inclusion criteria. There were three human epidemiological studies and eight animal experimental studies included in this paper. Four animal studies reported positive bone structural changes with vitamin E supplementation. The rest of the studies had negative changes or no effect. Studies with positive changes reported better effects with tocotrienol vitamin E isomer supplementation. Conclusions. This evidence-based review underscores the potential of vitamin E being used for osteoporosis. The effect of one of the vitamin E isomers, tocotrienols, on bone structural changes warrants further exploration. Controlled human observational studies should be conducted to provide stronger evidence.

Role of endogenous vitamin E in renal ischemic preconditioning process: differences between male and female rats

BACKGROUND

Antioxidants such as α-tocopherol (vitamin E) and β-carotene (vitamin A) play an important role in protective effect of repeated brief periods of ischemia, namely ischemic preconditioning (IPC). Values of these antioxidants were investigated and compared after induction of ischemia reperfusion (IR) and kidney IPC in both male and female rats.

METHODS

Forty eight Wistar rats were divided randomly into six groups of 8: groups A and B (male and female controls, respectively), group C (male IR or IR cases), group D (female IR cases) and groups E and F (male and female IPC cases, respectively). In groups C and D, ischemia was induced by clamping of left renal arteries for 45 min. In groups E and F, rats underwent four cycles of 4 min of arterial clamping and 11 min of de-clamping before final 45 min ischemia induction. Afterward, serum was collected to assess the blood urea nitrogen, creatinine and vitamins E and A values. Renal tissues were obtained for histological assessments.

RESULTS

α-tocopherol levels in male and female rats showed a significant increase in IPC compared with IR group (P<0.01) and also in female IPC compared with male IPC group. β-carotene levels had no significant variations. Histological evaluation showed that IR-induced renal injuries were less in female rats. Also, protective effects of IPC were more in female rats (P<0.01).

CONCLUSIONS

Renal IPC reduced damages in both male and female rats, but tissue injuries in females were decreased much more along with the increase of endogenous vitamin E.

Vitamin E deficiency impairs the somatostatinergic receptor-effector system and leads to phosphotyrosine phosphatase overactivation and cell death in the rat hippocampus

Vitamin E plays an essential role in maintaining the structure and function of the nervous system, and its deficiency, commonly associated with fat malabsorption diseases, may reduce neuronal survival. We previously demonstrated that the somatostatinergic system, implicated in neuronal survival control, can be modulated by α-tocopherol in the rat dentate gyrus, increasing cyclic adenosine monophosphate response element binding protein phosphorylation. To gain a better understanding of the molecular actions of tocopherols and examine the link among vitamin E, somatostatin and neuronal survival, we have investigated the effects of a deficiency and subsequent administration of tocopherol on the somatostatin signaling pathway and neuronal survival in the rat hippocampus. No changes in somatostatin expression were detected in vitamin-E-deficient rats. These rats, however, showed a significant increase in the somatostatin receptor density and dissociation constant, which correlated with a significant increase in the protein levels of somatostatin receptors. Nevertheless, vitamin E deficiency impaired the ability of the somatostatin receptors to couple to the effectors adenylyl cyclase and phosphotyrosine phosphatase by diminishing Gi protein functionality. Furthermore, vitamin E deficiency significantly increased phosphotyrosine phosphatase activity and PTPη expression, as well as PKCδ activation, and decreased extracellular-signal-regulated kinase phosphorylation. All these changes were accompanied by an increase in neuronal cell death. Subsequent α-tocopherol administration partially or completely reversed all these values to control levels. Altogether, our results prove the importance of vitamin E homeostasis in the somatostatin receptor-effector system and suggest a possible mechanism by which this vitamin may regulate the neuronal cell survival in the adult hippocampus.

Serum α-tocopherol and γ-tocopherol concentrations and prostate cancer risk in the PLCO Screening Trial: a nested case-control study

BACKGROUND

Vitamin E compounds exhibit prostate cancer preventive properties experimentally, but serologic investigations of tocopherols, and randomized controlled trials of supplementation in particular, have been inconsistent. Many studies suggest protective effects among smokers and for aggressive prostate cancer, however.

METHODS

We conducted a nested case-control study of serum α-tocopherol and γ-tocopherol and prostate cancer risk in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, with 680 prostate cancer cases and 824 frequency-matched controls. Multivariate-adjusted, conditional logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CIs) for tocopherol quintiles.

RESULTS

Serum α-tocopherol and γ-tocopherol were inversely correlated (r = -0.24, p<0.0001). Higher serum α-tocopherol was associated with significantly lower prostate cancer risk (OR for the highest vs. lowest quintile = 0.63, 95% CI 0.44-0.92, p-trend 0.05). By contrast, risk was non-significantly elevated among men with higher γ-tocopherol concentrations (OR for the highest vs. lowest quintile = 1.35, 95% CI 0.92-1.97, p-trend 0.41). The inverse association between prostate cancer and α-tocopherol was restricted to current and recently former smokers, but was only slightly stronger for aggressive disease. By contrast, the increased risk for higher γ-tocopherol was more pronounced for less aggressive cancers.

CONCLUSIONS

Our findings indicate higher α-tocopherol status is associated with decreased risk of developing prostate cancer, particularly among smokers. Although two recent controlled trials did not substantiate an earlier finding of lower prostate cancer incidence and mortality in response to supplementation with a relatively low dose of α-tocopherol, higher α-tocopherol status may be beneficial with respect to prostate cancer risk among smokers. Determining what stage of prostate cancer development is impacted by vitamin E, the underlying mechanisms, and how smoking modifies the association, is needed for a more complete understanding of the vitamin E-prostate cancer relation.

Non-antioxidant properties of α-tocopherol reduce the anticancer activity of several protein kinase inhibitors in vitro

The antioxidant properties of α-tocopherol have been proposed to play a beneficial chemopreventive role against cancer. However, emerging data also indicate that it may exert contrasting effects on the efficacy of chemotherapeutic treatments when given as dietary supplement, being in that case harmful for patients. This dual role of α-tocopherol and, in particular, its effects on the efficacy of anticancer drugs remains poorly documented. For this purpose, we studied here, using high throughput flow cytometry, the direct impact of α-tocopherol on apoptosis and cell cycle arrest induced by different cytotoxic agents on various models of cancer cell lines in vitro. Our results indicate that physiologically relevant concentrations of α-tocopherol strongly compromise the cytotoxic and cytostatic action of various protein kinase inhibitors (KI), while other classes of chemotherapeutic agents or apoptosis inducers are unaffected by this vitamin. Interestingly, these anti-chemotherapeutic effects of α-tocopherol appear to be unrelated to its antioxidant properties since a variety of other antioxidants were completely neutral toward KI-induced cell cycle arrest and cell death. In conclusion, our data suggest that dietary α-tocopherol could limit KI effects on tumour cells, and, by extent, that this could result in a reduction of the clinical efficacy of anti-cancer treatments based on KI molecules.