Vitamin E and heart disease: basic science to clinical intervention trials

Endogenous chemicals guard health through inhibiting ferroptotic cell death

Ferroptosis is a new form of regulated cell death caused by iron-dependent accumulation of lethal polyunsaturated phospholipids peroxidation. It has received considerable attention owing to its putative involvement in a wide range of pathophysiological processes such as organ injury, cardiac ischemia/reperfusion, degenerative disease and its prevalence in plants, invertebrates, yeasts, bacteria, and archaea. To counter ferroptosis, living organisms have evolved a myriad of intrinsic efficient defense systems, such as cyst(e)ine-glutathione-glutathione peroxidase 4 system (cyst(e)ine-GPX4 system), guanosine triphosphate cyclohydrolase 1/tetrahydrobiopterin (BH4) system (GCH1/BH4 system), ferroptosis suppressor protein 1/coenzyme Q10 system (FSP1/CoQ10 system), and so forth. Among these, GPX4 serves as the only enzymatic protection system through the reduction of lipid hydroperoxides, while other defense systems ultimately rely on small compounds to scavenge lipid radicals and prevent ferroptotic cell death. In this article, we systematically summarize the chemical biology of lipid radical trapping process by endogenous chemicals, such as coenzyme Q10 (CoQ10), BH4, hydropersulfides, vitamin K, vitamin E, 7-dehydrocholesterol, with the aim of guiding the discovery of novel ferroptosis inhibitors.

Vitamin E supplementation (alone or with other antioxidants) and stroke: a meta-analysis

CONTEXT

A previous study showed that vitamin E is effective in reducing the incidence of myocardial infarction only when it is taken in the absence of other antioxidants. It is unclear if it also reduces the incidence of stroke.

OBJECTIVE

The aim of this meta-analysis is to compare the effect of vitamin E supplementation alone or combined with other antioxidants on the incidence of stroke.

DATA SOURCES

A search was performed in the following databases: PubMed, ISI Web of Science, SCOPUS, and Cochrane Library.

DATA EXTRACTION

Sixteen randomized controlled trials were selected to evaluate the effect of vitamin E supplementation on stroke.

DATA ANALYSIS

The range of vitamin E doses used was 33-800 IU. The follow-up period ranged from 6 months to 9.4 years. Compared with controls, when vitamin E was given alone it did not reduce the incidence of ischemic and hemorrhagic stroke. Conversely, compared with controls, supplementation of vitamin E with other antioxidants reduced ischemic stroke (random effects, RR: 0.91; 95% CI: 0.84-0.99; P = 0.02) but with a significant increase in hemorrhagic stroke (random effects, RR: 1.22; 95% CI: 1.0-1.48; P = 0.04).

CONCLUSIONS

Supplementation with vitamin E alone is not associated with stroke reduction. Instead, supplementation of vitamin E with other antioxidants reduces the incidence of ischemic stroke but increases the risk of hemorrhagic stroke, cancelling any beneficial effect derived. Thus, vitamin E is not recommended in stroke prevention.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42022258259.

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.

The Potential Antiviral Effects of Selenium Nanoparticles and Coated Surfaces

Modern epidemics quickly spread across borders and continents with devastating effects on both human health and the world economy. This issue is made worse by the various ways that infections are spread, including through aerosol, droplets, and fomites. The antibacterial qualities of various surface materials and coatings have been the subject of much research. However, the antiviral activity of metal coatings can be heavily influenced by imbalances in metal distribution and the presence of other metal impurities. As such, there is interest in developing novel surface coatings that can reduce the transmission of active viral particles in healthcare facilities. In recent years, the non-metals, such as selenium and nanoparticles, have acquired greater interest from the medical and scientific community for their antiviral surface activity. In this review, we will discuss the cellular and physiological functions of selenium in mammalian cells and against viral infections. We then discuss the mechanism behind selenium coated surfaces and their efficacy against bacterial infections. Lastly, we examine the antiviral activity of selenium, and the potential antiviral activity of selenium nanoparticles and coatings.

Exploring multifunctional antioxidants as potential agents for management of neurological disorders

Free radical or oxidative stress may be a fundamental mechanism underlying several human neurologic diseases. Therapy using free radical scavengers (antioxidants) has the potential to prevent, delay, or ameliorate many neurologic disorders. However, the biochemistry of oxidative pathobiology is complex, and optimum antioxidant therapeutic options may vary and need to be tailored to individual diseases. In vitro and animal model studies support the potential beneficial role of various antioxidant compounds in neurological disease. Antioxidants generally play an important role in reducing or preventing the cell damage and other changes which occur in the cells like mitochondrial dysfunction, DNA mutations, and lipid peroxidation in the cell membrane. Based on their mechanism of action, antioxidants can be used to treat various neurological disorders like Huntington's disease, Alzheimer's disease, and Parkinson's disease. Vitamin E has a scavenging action for reactive oxygen species (ROS) and also prevents the lipid peroxidation. Creatine generally reduces the mitochondrial dysfunction in Parkinson's disease (PD) patients. Various metal chelators are used in PD for the prevention of accumulation of the metals. Superoxidase dismutase (SOD), lipases, and proteases act as repair enzymes in patients with AD. Accordingly, the antioxidant defense system is found to be most useful for treating various neurological disorders.

Interventional study with vitamin E in cardiovascular disease and meta-analysis

Cardiovascular disease (CVD) is one of the major causes of morbidity and mortality and atherosclerosis is the common root to most of the CVD. Oxidative stress is one of the most important factors driving atherosclerosis and its complications. Thus, strategies for the prevention and treatment of cardiovascular events had oxidative changes as a potential target. Natural vitamin E consists of a family of eight different compounds, four tocopherols and four tocotrienols. All tocopherols and tocotrienols are potent antioxidants with lipoperoxyl radical-scavenging activities. In addition, α-tocopherol possesses also anti-inflammatory as well as anti-atherothrombotic effects by modulating platelet and clotting system. Experimental and in vitro studies described molecular and cellular signalling pathways regulated by vitamin E antithrombotic and antioxidant properties. While observational studies demonstrated an inverse association between vitamin E serum levels and CVD, interventional trials with vitamin supplements provided negative results. This review focus on the impact of vitamin E in the atherothrombotic process and describes the results of experimental and clinical studies with the caveats related to the interventional trials with vitamin E to prevent CVD.

Effectiveness of Some Vitamins in the Prevention of Cardiovascular Disease: A Narrative Review

By virtue of their regulatory role in various metabolic and biosynthetic pathways for energy status and cellular integrity, both hydro-soluble and lipo-soluble vitamins are considered to be involved in maintaining cardiovascular function in health and disease. Deficiency of some vitamins such as vitamin A, B₆, folic acid, C, D, and E has been shown to be associated with cardiovascular abnormalities whereas supplementation with these vitamins has been claimed to reduce cardiovascular risk for hypertension, atherosclerosis, myocardial ischemia, arrhythmias, and heart failure. However, the data from several experimental and clinical studies for the pathogenesis of cardiovascular disease due to vitamin deficiency as well as therapy due to different vitamins are conflicting. In this article, we have attempted to review the existing literature on the role of different vitamins in cardiovascular disease with respect to their deficiency and supplementation in addition to examining some issues regarding their involvement in heart disease. Although both epidemiological and observational studies have shown some merit in the use of different antioxidant vitamins for the treatment of cardiovascular disorders, the results are not conclusive. Furthermore, in view of the complexities in the mechanisms of different cardiovascular disorders, no apparent involvement of any particular vitamin was seen in any specific cardiovascular disease. On the other hand, we have reviewed the evidence that deficiency of vitamin B₆ promoted KCl-induced Ca²⁺ entry and reduced ATP-induced Ca²⁺-entry in cardiomyocytes in addition to decreasing sarcolemmal (SL) ATP binding. The active metabolite of vitamin B₆, pyridoxal 5′-phosphate, attenuated arrhythmias due to myocardial infarction (MI) as well as cardiac dysfunction and defects in the sarcoplasmic reticulum (SR) Ca²⁺-transport in the ischemic-reperfused hearts. These observations indicate that both deficiency of some vitamins as well as pretreatments with different vitamins showing antioxidant activity affect cardiac function, metabolism and cation transport, and support the view that antioxidant vitamins or their metabolites may be involved in the prevention rather than the therapy of cardiovascular disease.

SURVEY OF GERIATRIC ELEPHANT MEDICAL CARE, NUTRITION, HUSBANDRY, AND WELFARE

Improvements in husbandry, veterinary care, and nutrition have led to increased longevity of animals in human care, including elephants. The goal of this study was to collect and synthesize information pertaining to geriatric elephant medicine, management, husbandry, and nutrition. An electronic survey was created and distributed to American Association of Zoo Veterinarians members through an online link. A total of 61 responses were received from veterinarians, nutritionists, and elephant managers with data encompassing 314 elephants, of which 142 were geriatric (over 40 years old) and 51 were on their final set of molars. Following the initial survey, willing respondents were contacted for follow-up interviews. Osteoarthritis, foot disease, and colic were the most commonly reported diseases, and flunixin meglumine and phenylbutazone were the analgesics most often used. Respondents described diseases treated, husbandry changes specific for older animals, welfare assessments and quality of life monitoring, nutritional modifications for dental attrition, a variety of integrative medicine modalities, and unique cases. It is the hope that the information identified in this study can be used to improve treatment, management practices, and overall welfare for geriatric elephants.

Identification of new biologically active synthetic molecules: comparative experimental and theoretical studies on the structure-antioxidant activity relationship of cyclic 1,3-ketoamides

Antioxidant agent is a chemical that prevents the oxidation of other chemical substances. Its use is the most effective means of protecting the organism by neutralizing the harmful effects of free radicals caused by oxidative stress. In the present work, a series of β-ketoamides containing a variety of monosubstituted amide groups were synthesized and tested as antioxidant agents. In order to establish a possible structure-antioxidant activity relationship, we are presenting a systematic theoretical study of these molecules with the aim of clarifying the active sites. In particular, we discuss the selectivity resulting from the choice of a free radical/antioxidant system. The theoretical study of these molecules was carried out using density functional theory (DFT) calculations at the B3LYP/6-311G (d,p) level of theory. In order to shed light on the antioxidant properties of β-ketoamides, O-H bond dissociation enthalpies (BDEs), ionization potentials (IPs), electron affinities (EAs), proton affinities (PAs), and electron transfer enthalpies (ETEs) are performed in the gas phase and in ethanol. The results obtained show that the HAT mechanism is thermodynamically more favored in the gas phase, while the SPLET is preferred in the polar solvent.

Density Functional Theory Studies on the Antioxidant Mechanism and Electronic Properties of Some Bioactive Marine Meroterpenoids: Sargahydroquionic Acid and Sargachromanol

Certain meroterpenoids isolated from brown alga of the genus Sargassum are known to be antioxidant agents. Herein, density functional theory has been performed to analyze the preferred antioxidant mechanism of the two reactive antioxidant compounds derived from the Sargassum genus, that is, Sargahydroquinoic acid and Sargachromanol and some of their derivatives. Their global reactivity descriptors have been calculated to reveal their reactivity as an antioxidant. Molecule 1 is the most reactive antioxidant according to calculated descriptors. The results of molecule 1 are comparable to that of Trolox, suggesting their similar activity. The calculated descriptors are closely matched with experimental pieces of evidence. It has been found that hydrogen atom transfer (HAT) is more favored in gas media. Also, the effect of solvent polarity on the antioxidant activity has been explored for molecule 1. The results disclose that the polarity of the solvent increases the contribution of two other mechanisms, that is, single-electron transfer, followed by proton transfer and sequential proton loss electron transfer.

The Role of Oxidative Stress in Cardiac Disease: From Physiological Response to Injury Factor

Reactive oxygen species (ROS) are highly reactive chemical species containing oxygen, controlled by both enzymatic and nonenzymatic antioxidant defense systems. In the heart, ROS play an important role in cell homeostasis, by modulating cell proliferation, differentiation, and excitation-contraction coupling. Oxidative stress occurs when ROS production exceeds the buffering capacity of the antioxidant defense systems, leading to cellular and molecular abnormalities, ultimately resulting in cardiac dysfunction. In this review, we will discuss the physiological sources of ROS in the heart, the mechanisms of oxidative stress-related myocardial injury, and the implications of experimental studies and clinical trials with antioxidant therapies in cardiovascular diseases.

Effect of Vitamins C and E Co-Supplementation on Serum C-Reactive Protein Level: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Studies assessing the effect of vitamin C and E co-supplementation on levels of circulating C-reactive protein (CRP) show contradictory results. We carried out a systematic review and meta-analysis of randomized controlled trials (RCTs) to assess the effect of vitamin C and E co-supplementation on CRP. A systematic search was carried out using PubMed, Scopus, Ovid, Cochrane, Embase, and the Web of Science without any language or time restriction (until 31 March 2019) to retrieve RCTs that examined the effect of vitamin C and E co-supplementation on CRP. A meta-analysis was carried out using a random effects model, and I² indexes were used to evaluate the heterogeneity. The search yielded 5,134 publications, including 8 eligible RCTs. The results indicate that vitamin C and E co-supplementation does not significantly impact levels of serum CRP [weighted mean difference and 95% confidence interval with random effects model analysis: −0.22 mg/L (−0.85, 0.41), P=0.5]. Subgroup analysis demonstrated that vitamin C and E co-supplementation significantly reduced serum CRP in participants ≥30 years of age, but significantly increased serum CRP in participants <30 years of age. The results of this meta-analysis indicate beneficial effects of vitamins C and E co-supplementation on CRP in participants ≥30 years of age, and not in younger participants. To confirm these results, further well-designed RCTs are needed.

Q10 Coenzyme Supplementation can Improve Oxidative Stress Response to Exercise in Metabolic Syndrome in Rats

Abstract. Background: The metabolic syndrome leads to high morbidity and mortality. Almost all pathological states are associated with oxidative stress (OS) disorders. This study evaluates the effects of Coenzyme Q10 (CoQ10) supplementation on different lifestyles, in relation to serum and tissue OS parameters. Materials and methods: Twelve Wistar rat groups (10 rats/group) were equally divided in three types of diets: standard (St), high fat (HF), high sugar (HS); within each diet group there was one sedentary group with CoQ10 supplementation (100 mg/kg body weight), one sedentary without CoQ10, one trained group with CoQ10 and one trained group without CoQ10 supplementation. After 28 days blood samples were collected as follows: after 12 hours of fasting (T0), 1 hour postprandial (T1) and after 1 hour of exercise (T2) or sedentary postprandial time (T3). Thiol groups (SH) and malondialdehyde (MDA) were determined from serum and liver homogenate. Results: Significant changes were observed in fasting MDA for HF (p = 0.024 for training, 0.028 for CoQ10). Postprandial, OS status altered, with highest MDA in HF sedentary non-CoQ10 group (3.92 ± 0.37 vs 2.67 ± 0.41 nmol/ml in St trained CoQ10). At T2 the untrained and non-CoQ10 groups had the highest MDA levels (up to 22.3% vs T1, p < 0.001 in HF) as SH dropped (34.4% decrease vs T1, p < 0.001 in HF). At T3 high MDA levels were observed, correlated with low SH (Pearson r = −0.423 overall), irrespective of the CoQ10 supplementation. CoQ10 improved the liver OS status (MDA and SH decreased), but not the exercise, in all diets. Conclusions: CoQ10 supplementation accompanied by chronic exercise improved the OS serum profile, irrespective of the daily diet. CoQ10 lowered liver MDA and SH concentrations.

Dietary intervention reduces left atrial enlargement in dogs with early preclinical myxomatous mitral valve disease: a blinded randomized controlled study in 36 dogs

Background

Myxomatous mitral valve disease (MMVD), the most common naturally-occurring heart disease in dogs, is associated with alterations in energy metabolism, oxidative stress and inflammation. Energy deprivation plays a causal role in the development of heart failure. This study was designed to determine if a cardiac protection blend (CPB) of nutrients containing medium-chain triglycerides as an alternative energy source, fish oil to reduce inflammation, antioxidants, and other key nutrients important to cardiac health and function could slow or prevent MMVD progression. Nineteen dogs with early stage MMVD and 17 breed-, age-, and sex-matched healthy dogs were enrolled for a 6-month blinded, placebo-controlled study. Dogs in each cardiac health group were randomly assigned to either control diet (CON) or CPB-supplemented diet. Echocardiography was performed at baseline, 3 months and 6 months.

Results

No changes were found in healthy dogs. While MMVD-CON dogs had an average 10% increase over baseline in left atrial diameter (LAD) and left atrial to aortic root ratio (LA/Ao) at 6 months, MMVD-CPB dogs showed 3% decreases, resulting significant diet by time interactions (P = 0.037, P = 0.005, respectively). More MMVD-CON dogs progressed from stage B1 to B2 during the study. A positive correlation was found between 6-month changes in LAD and blood pressures in MMVD-CPB dogs (systolic: P = 0.050, diastolic: P = 0.035) but not MMVD-CON dogs.

Conclusions

Our results demonstrated efficacy of CPB-based dietary intervention in reducing LA size and mitral regurgitation, and in slowing or preventing the progression of early MMVD in dogs.

Differentiation Between Unfiltered and Filtered Oblica and Leccino cv. Virgin Olive Oils

The quality parameters, a variety of microcomponents, and the sensory characteristics of Oblica and Leccino cv. virgin olive oils (VOOs) were evaluated before and after filtration process adopted in order to estimate the individual varietal compositional changes. The dynamics of the formation of hydrolytic and oxidative changes in unfiltered (UF) and filtered (F) oils was asses by comparing level of free fatty acids (FFA), peroxide value (PV), and spectrophotometric indices periodically during 1 year of oil storage. An analysis of phenolics, tocopherols, and fatty acids was determined by chromatographic (HPLC and GC) and spectrometric methods, oxidative stability by Rancimat method while sensory analyses of obtained olive oils were performed by a trained professional panel. Single monovarietal VOO loses phenols in different rate with the applied filtration. Total secoiridoids decreases significantly in "Oblica" VOOs while no changes in their concentrations were found between unfiltered and filtered "Leccino" oils. Intensity of desired sensory properties decreases with filtration. In "Leccino" VOOs decrease of oxidative stability was more pronounced. After 12 months of storage, filtered "Leccino" VOOs had significantly lower FFA values than observed for the unfiltered counterparts. Further, there were no significant changes in PV and K²⁷⁰ values between unfiltered and filtered oils of both studied varietal oils. Storage time influenced more studied quality parameters than filtration, during which PV of unfiltered oils faster deteriorate. The highest changes between stored and corresponding fresh samples were exhibited in unfiltered "Oblica" VOOs. PRACTICAL APPLICATION: Quality enhancement of olive oil is constantly being done professionally and scientifically. The information provided in this study can be used in the industry of olive oil for improve the phenolic content, oxidative stability, and the sensory quality of virgin olive oils. The findings of stability test could be guidelines for mindful leading of the oil finishing up to bottling.

Review on nutritional composition of orange-fleshed sweet potato and its role in management of vitamin A deficiency

A wide variety of the roots and tubers plays a major role in human diet, animal feed, and industrial raw materials. Sweet potatoes (SPs) play an immense role in human diet and considered as second staple food in developed and underdeveloped countries. Moreover, SP production and management need low inputs compared to the other staple crops. The color of SP flesh varied from white, yellow, purple, and orange. Scientific studies reported the diversity in SP flesh color and connection with nutritional and sensory acceptability. Among all, orange-fleshed sweet potato (OFSP) has been attracting food technologists and nutritionists due to its high content of carotenoids and pleasant sensory characteristics with color. Researchers reported the encouraging health effects of OFSP intervention into the staple food currently practicing in countries such as Uganda, Mozambique, Kenya, and Nigeria. Scientific reviews on the OFSP nutritional composition and role in vitamin A management (VAM) are hardly available in the published literature. So, this review is conducted to address the detailed nutritional composition (proximate, mineral, carotenoids, vitamins, phenolic acids, and antioxidant properties), role in vitamin A deficiency (VAD) management, and different food products that can be made from OFSP.

DFT Studies on the Antioxidant Activity of Naringenin and Its Derivatives: Effects of the Substituents at C3

The radical scavenging activity of a flavonoid is largely influenced by its structure. The effects of the substituents at C3 position on the antioxidant activity of naringenin were carried out using the density functional theory (DFT) method. The reaction enthalpies related with the three well-established mechanisms were analyzed. Excellent correlations were found between the reaction enthalpies and Hammett sigma constants. Equations obtained from the linear regression can be helpful in the selection of suitable candidates for the synthesis of novel naringenin derivatives with enhanced antioxidant properties. In the gas and benzene phases, the antioxidant activity of naringenin was enhanced by the electron-donating substituents via weakening the bond dissociation enthalpy (BDE). In the water phase, it was strengthened by electron-withdrawing groups—via lowering the proton affinity (PA). The electronic effect of the substituent on the BDE of naringenin is mainly governed by the resonance effect, while that on the ionization potential (IP) and PA of naringenin is mainly controlled by the field/inductive effect.

Synthesis and radical-scavenging activity of C-methylated fisetin analogues

The radical-scavenging reaction of fisetin, a natural antioxidant found in strawberries, is known to proceed via hydrogen transfer to produce a fisetin radical intermediate. Thus, introduction of an electron-donating group into the fisetin molecule is expected to stabilize the radical, leading to enhanced radical-scavenging activity. In this study, fisetin derivatives in which methyl substituents were introduced at the ortho positions relative to the catechol hydroxyl groups were synthesized and their radical scavenging activities were evaluated and compared with that of the parent fisetin molecule. Among the methyl derivatives, 5'-methyl fisetin, in which the inherent planar structure of fisetin was retained, exhibited the strongest radical scavenging activity. Introduction of methyl substituents may be effective for the enhancement of various biological activities of antioxidants, particularly radical-scavenging activity.

Hepatoprotective effects of vitamin E against hexachlorobenzene-induced hepatotoxicity and oxidative stress in rats: histological, biochimical and antioxidant status changes

The protective effects of α-Tocopherol (vitamin E) on liver injury induced by hexachlorobenzene (HCB) were investigated in adult male rats of Wistar strain. Animals were randomly divided into six groups of eight rats each. Group 1 and 2 have received HCB, dissolved in olive oil, at a dose of 4 mg or 16 mg/kg b.w., respectively. Group 3 and 4 were treated by the same doses of HCB (4 mg and 16 mg/kg b.w.) after 1 h of pretreatment with α-tocopherol at a dose of 100 mg kg^-1 b.w. The other two groups served as controls; which received either olive oil only, a solvent of HCB, or α-tocopherol. A significant increase in hepatic lipid peroxidation (LPO) and GSH activity were observed following HCB administration. The activities of antioxidant enzymes like superoxide dismutase and catalase were significantly decreased while glutathione peroxidase was significantly increased following HCB administration. Similarly, a significant increase in plasma levels of various marker enzymes [aminotransferase (aspartate aminotransférase (AST) and alanine aminotransferase (ALT)), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH)] and a decrease of total protein level were observed. Pretreatment with vitamin E of HCB treated rats ameliorated all biochemical parameters to near normal values. Liver histological study confirmed biochemical parameters and the beneficial role of vitamin E.

Monitoring dynamic release of intracellular hydrogen peroxide through a microelectrode based enzymatic biosensor

A high sensitive and selective hydrogen peroxide (H₂O₂) biosensor was fabricated on the basis of reduced hemoglobin (Hb) and single-walled carbon nanotubes (SWCNTs) for detecting the release of H₂O₂ from living HepG2 cancer cells in the process of the in situ biosynthesis of ZnO quantum. The modification of carbon fiber microelectrode (CFME) was carried out by physical adsorption. By the scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), the dense cover of surface and successful immobilization were characterized. Electrochemical investigation demonstrates that the as-prepared modified microelectrode showed a quasi-reversible process toward the reduction of H₂O₂, which exhibited a linear range from 0.51 to 10.6 μM, with a limit of detection of 0.23 μM. This microelectrode biosensor was applied for the quantification of the change of H₂O₂ concentration released from HepG2 cells through the in situ biosynthesis of ZnO quantum dots, which was further confirmed by the fluorescence staining.

Natural approaches in metabolic syndrome management

Metabolic syndrome (MetS) is characterized as a group of cardiometabolic risk factors that raise the risk for heart disease and other health problems, such as diabetes mellitus and stroke. Treatment strategies include pharmacologic interventions and supplementary (or "alternative") treatments. Nutraceuticals are derived from food sources (isolated nutrients, dietary supplements and herbal products) that are purported to provide health benefits, in addition to providing basic nutritional value. Nutraceuticals are claimed to prevent chronic diseases, improve health, delay the aging process, increase life expectancy, and support the structure and function of the body. The study of the beneficial effects of nutraceuticals in patients with MetS, including product standardization, duration of supplementation and definition of optimal dosing, could help better define appropriate treatment. This review focuses on widely marketed nutraceuticals (namely polyphenols, omega-3 fatty acids, macroelements and vitamins) with clinically demonstrated effects on more than one component of MetS.

Atherothrombosis and Oxidative Stress: Mechanisms and Management in Elderly

SIGNIFICANCE

The incidence of cardiovascular events (CVEs) increases with age, representing the main cause of death in an elderly population. Aging is associated with overproduction of reactive oxygen species (ROS), which may affect clotting and platelet activation, and impair endothelial function, thus predisposing elderly patients to thrombotic complications. Recent Advances: There is increasing evidence to suggest that aging is associated with an imbalance between oxidative stress and antioxidant status. Thus, upregulation of ROS-producing enzymes such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and myeloperoxidase, along with downregulation of antioxidant enzymes, such as superoxide dismutase and glutathione peroxidase, occurs during aging. This imbalance may predispose to thrombosis by enhancing platelet and clotting activation and eliciting endothelial dysfunction. Recently, gut-derived products, such as trimethylamine N-oxide (TMAO) and lipopolysaccharide, are emerging as novel atherosclerotic risk factors, and gut microbiota composition has been shown to change by aging, and may concur with the increased cardiovascular risk in the elderly.

CRITICAL ISSUES

Antioxidant treatment is ineffective in patients at risk or with cardiovascular disease. Further, anti-thrombotic treatment seems to work less in the elderly population.

FUTURE DIRECTIONS

Interventional trials with antioxidants targeting enzymes implicated in aging-related atherothrombosis are warranted to explore whether modulation of redox status is effective in lowering CVEs in the elderly. Antioxid. Redox Signal. 27, 1083-1124.

The Ameliorative Effects of a Tocotrienol-Rich Fraction on the AGE-RAGE Axis and Hypertension in High-Fat-Diet-Fed Rats with Metabolic Syndrome

The clinical value of tocotrienols is increasingly appreciated because of the unique therapeutic effects that are not shared by tocopherols. However, their effect on metabolic syndrome is not well-established. This study aimed to investigate the effects of a tocotrienol-rich fraction (TRF) from palm oil in high-fat-diet-treated rats. Male, post-weaning Sprague Dawley rats were provided high-fat (60% kcal) diet for eight weeks followed by a TRF (60 mg/kg) treatment for another four weeks. Physical, metabolic, and histological changes were compared to those on control and high-fat diets respectively. High-fat feeding for eight weeks induced all hallmarks of metabolic syndrome. The TRF reversed systolic and diastolic hypertension, hypercholesterolemia, hepatic steatosis, impaired antioxidant defense, and myeloperoxidase hyperactivity triggered by the high-fat diet. It also conferred an inhibitory effect on protein glycation to reduce glycated hemoglobin A1c and advanced glycation end products (AGE). This was accompanied by the suppression of the receptor for advanced glycation end product (RAGE) expression in the liver. The treatment effects on visceral adiposity, glycemic control, triglyceride level, as well as peroxisome proliferator-activated receptor α and γ expression were negligible. To conclude, treatment with a TRF exhibited protective effects on the cardiovascular and liver health in addition to the amelioration of plasma redox imbalance and AGE-RAGE activation. Further investigation as a therapy for metabolic syndrome is therefore worthwhile.

Synthesis of methylated quercetin analogues for enhancement of radical-scavenging activity

Methylation of the catechol moiety of quercetin resulted in the enhancement of its radical-scavenging activity.

Tocopherols and Tocotrienols in Common and Emerging Dietary Sources: Occurrence, Applications, and Health Benefits

Edible oils are the major natural dietary sources of tocopherols and tocotrienols, collectively known as tocols. Plant foods with low lipid content usually have negligible quantities of tocols. However, seeds and other plant food processing by-products may serve as alternative sources of edible oils with considerable contents of tocopherols and tocotrienols. Tocopherols are among the most important lipid-soluble antioxidants in food as well as in human and animal tissues. Tocopherols are found in lipid-rich regions of cells (e.g., mitochondrial membranes), fat depots, and lipoproteins such as low-density lipoprotein cholesterol. Their health benefits may also be explained by regulation of gene expression, signal transduction, and modulation of cell functions. Potential health benefits of tocols include prevention of certain types of cancer, heart disease, and other chronic ailments. Although deficiencies of tocopherol are uncommon, a continuous intake from common and novel dietary sources of tocopherols and tocotrienols is advantageous. Thus, this contribution will focus on the relevant literature on common and emerging edible oils as a source of tocols. Potential application and health effects as well as the impact of new cultivars as sources of edible oils and their processing discards are presented. Future trends and drawbacks are also briefly covered.

Tocopherols in Seafood and Aquaculture Products

Fish products contain various nutritionally beneficial components, namely, ω3-polyunsaturated fatty acids (ω3-PUFA), minerals, and vitamins. Particularly, tocopherols (α-, β-, γ-, and δ-tocopherol) can be provided by seafood and aquaculture products. Hence, this review shows the various aspects of tocopherols in seafood and aquaculture products. For tocopherol determination in these products, HPLC methods coupled with diode array detection in the UV area of the spectrum or fluorescence detection have been shown as sensitive and accurate. These newest methods have helped in understanding tocopherols fate upon ingestion by seafood organisms. Tocopherols pass through the intestinal mucosa mainly by the same passive diffusion mechanism as fats. After absorption, the transport mechanism is thought to consist of two loops. The first loop is dietary, including chylomicrons and fatty acids bound to carrier protein, transporting lipids mainly to the liver. The other is the transport from the liver to tissues and storage sites. Moreover, tocopherol levels in fish organisms correlate with diet levels, being adjusted in fish body depending on diet concentration. For farmed fish species, insufficient levels of tocopherols in the diet can lead to poor growth performance or to nutritional disease. The tocopherol quantity needed as a feed supplement depends on various factors, such as the vitamer mixture, the lipid level and source, the method of diet preparation, and the feed storage conditions. Other ingredients in diet may be of great importance, it has been proposed that α-tocopherol may behave as a prooxidant synergist at higher concentrations when prooxidants such as transition metals are present. However, the antioxidant action of tocopherols outweighs this prooxidant effect, provided that adequate conditions are used. In fact, muscle-based foods containing higher levels of tocopherol show, for instance, higher lipid stability. Besides, tocopherols are important not only from the nutritional point of view but also from the physiological one, since they are involved in many metabolic processes in the human organism. Moreover, synergistic interactions with selenium and ascorbic acid have been reported. It deserves attention that there is evidence tocopherols taken with food can prevent heart disease, while no such evidence was found for α-tocopherol as supplement. From this perspective, eating fish is advisable, since, for instance, a 100 g serving of salmon may provide nearly 14% of recommended dietary allowance.

Nephroprotective and antioxidant significance of selenium and α-tocopherol on lead acetate-induced toxicity of Nile Tilapia (Oreochromis niloticus)

The kidney plays an important physiological function, maintaining the osmoregulation and electrolyte balance of Nile tilapia (Oreochromis niloticus). Selenium and α-tocopherol (α-toc) are potent antioxidants, which improve the aquaculture health. In this study, we tested the potential ability of selenium and α-toc to alleviate the oxidative stress in the kidney induced by lead toxicity. Two hundred and twenty-five O. niloticus were divided into five groups. The control group received a basal diet. Lead nephrotoxicity was induced by daily application of 73.40 mg lead acetate/liter water for up to 10 weeks. Selenium and α-tocopherol were given 1 week before lead intoxication. Selenium was administered as sodium selenite, 4 mg/kg dry diet. Alpha-tocopherol acetate was administered as α-toc, 200 mg/kg dry diet. The last group received a mixture of selenium and α-toc in diet. Fish treated with selenium and/or α-toc (groups III-V) showed an amelioration of the adverse effects of lead toxicity and significant improvement in serum electrolytes (calcium, inorganic phosphate, and magnesium) and creatinine level compared with the positive control group (P ≤ 0.05). Treated groups showed significant decrease in superoxide dismutase (SOD) and reduced glutathione (GSH) activity with significant increase in malondialdehyde (MDA; P ≤ 0.05). It could be concluded that selenium and α-toc have a potential antioxidant effect and have the ability to improve the kidney function after lead intoxication of O. niloticus.

Supplementation with vitamin E alone is associated with reduced myocardial infarction: a meta-analysis

BACKGROUND AND AIMS

Previous meta-analyses of interventional trials with vitamin E provided negative results but it remains unclear if this vitamin has some influence on cardiovascular events when supplemented alone. The aim of this study was to compare the effect of vitamin E alone or in combination with other antioxidants on myocardial infarction.

METHODS AND RESULTS

Pubmed, ISI Web of Science, SCOPUS and Cochrane database were searched without language restrictions. We investigated randomized clinical trials studying the effect of vitamin E supplementation on myocardial infarction. Sixteen randomized controlled trials of vitamin E treatment were analyzed in this meta-analysis. The dose range for vitamin E was 33-800IU. Follow-up ranged from 0.5 to 9.4 years. Compared to controls, vitamin E given alone significantly decreased myocardial infarction (3.0% vs 3.4%) (random effects R.R.: 0.82; 95% C.I., 0.70-0.96; p = 0.01). This effect was driven by reduction of fatal myocardial infarction (random effects R.R.: 0.84; 95% C.I., 0.73-0.96; p = 0.01).

CONCLUSIONS

When supplemented alone, vitamin E reduces myocardial infarction in interventional trials while it appears ineffective when associated with other antioxidants.

Effect of Gibberellin on the biosynthesis of tocopherols in Oilseed rape (Brassica napus L.) and arabidopsis

Elevating the yield and altering the composition of seed tocopherols (Toc’s) are important to rapeseed breeding and production. However, little is known about the biosynthesis of Toc’s in response to environmental signals. In this study, we investigated the effects of exogenous gibberellin (GA3) and paclobutrazol (PAC) on Toc biosynthesis. We also explored the interactive effects between the two plant growth regulators (PGRs) and other factors, such as PGR treatment duration, genotype, and growing location on the total Toc yield and composition in oilseed rape seed. GA3 significantly enhanced the production of Toc’s and elevated the α-/γ-Toc ratio in a time- and genotype-dependent manner. By contrast, PAC significantly reduced Toc yield. Genotypic differences were observed in the effects of GA3 on Toc yield and composition in the seeds. GA3 significantly increased the Toc yield and α-/γ-Toc ratio in Zheyou-50, a genotype with a low proportion of very long chain fatty acids (VLCFAs). However, GA3 did not significantly influence these parameters in Jiu-Er-13Xi, a genotype with a high VLCFA proportion. The increased Toc yield induced by GA3 was mediated by the upregulation of genes (BnPDS1 and BnVTE1) that catalyze the production of Toc precursors. Therefore, applying GA3 can improve rapeseed quality by increasing Toc yield and improving Toc composition.

Response of seed tocopherols in oilseed rape to nitrogen fertilizer sources and application rates

Tocopherols (Tocs) are vital scavengers of reactive oxygen species (ROS) and important seed oil quality indicators. Nitrogen (N) is one of the most important fertilizers in promoting biomass and grain yield in crop production. However, the effect of different sources and application rates of N on seed Toc contents in oilseed rape is poorly understood. In this study, pot trials were conducted to evaluate the effect of two sources of N fertilizer (urea and ammonium nitrate). Each source was applied to five oilseed rape genotypes (Zheshuang 72, Jiu-Er-1358, Zheshuang 758, Shiralee, and Pakola) at three different application rates (0.41 g/pot (N1), 0.81 g/pot (N2), and 1.20 g/pot (N3)). Results indicated that urea increased α-, γ-, and total Toc (T-Toc) more than did ammonium nitrate. N3 was proven as the most efficient application rate, which yielded high contents of γ-Toc and T-Toc. Highly significant correlations were observed between Toc isomers, T-Toc, and α-/γ-Toc ratio. These results clearly demonstrate that N sources and application rates significantly affect seed Toc contents in oilseed rape.

Antioxidants and human diseases

Oxidative stress plays a pivotal role in the development of human diseases. Reactive oxygen species (ROS) that includes hydrogen peroxide, hyphochlorus acid, superoxide anion, singlet oxygen, lipid peroxides, hypochlorite and hydroxyl radical are involved in growth, differentiation, progression and death of the cell. They can react with membrane lipids, nucleic acids, proteins, enzymes and other small molecules. Low concentrations of ROS has an indispensable role in intracellular signalling and defence against pathogens, while, higher amounts of ROS play a role in number of human diseases, including arthritis, cancer, diabetes, atherosclerosis, ischemia, failures in immunity and endocrine functions. Antioxidants presumably act as safeguard against the accumulation of ROS and their elimination from the system. The aim of this review is to highlight advances in understanding of the ROS and also to summarize the detailed impact and involvement of antioxidants in selected human diseases.

RNA Viruses: ROS-Mediated Cell Death

Reactive oxygen species (ROS) are well known for being both beneficial and deleterious. The main thrust of this review is to investigate the role of ROS in ribonucleic acid (RNA) virus pathogenesis. Much evidences has accumulated over the past decade, suggesting that patients infected with RNA viruses are under chronic oxidative stress. Changes to the body's antioxidant defense system, in relation to SOD, ascorbic acid, selenium, carotenoids, and glutathione, have been reported in various tissues of RNA-virus infected patients. This review focuses on RNA viruses and retroviruses, giving particular attention to the human influenza virus, Hepatitis c virus (HCV), human immunodeficiency virus (HIV), and the aquatic Betanodavirus. Oxidative stress via RNA virus infections can contribute to several aspects of viral disease pathogenesis including apoptosis, loss of immune function, viral replication, inflammatory response, and loss of body weight. We focus on how ROS production is correlated with host cell death. Moreover, ROS may play an important role as a signal molecule in the regulation of viral replication and organelle function, potentially providing new insights in the prevention and treatment of RNA viruses and retrovirus infections.

α-Tocopherol protects keratinocytes against ultraviolet A irradiation by suppressing glutathione depletion, lipid peroxidation and reactive oxygen species generation

This study aimed to investigate whether α-tocopherol is able to protect keratinocytes against ultraviolet A (UVA) radiation by increasing glutathione (γ-glutamylcysteinylglycine; GSH) levels or decreasing lipid peroxidation and reactive oxygen species (ROS) generation. The cell survival fraction was 43.6% when keratinocytes were irradiated with UVA at a dose of 8 J/cm². α-Tocopherol was added prior to UVA irradiation and the cell viability was assayed. The cell survival fractions were 60.2, 77.1, 89.0, 92.9 and 96.2% when α-tocopherol was added at concentrations of 2.9, 5.9, 8.8, 11.8 and 14.7 IU/ml, respectively. These results suggested that α-tocopherol is capable of protecting keratinocytes against UVA irradiation. Furthermore, the levels of GSH, lipid peroxidation and ROS were measured. The levels of GSH were 0.354 and 0.600 mmol/g protein in keratinocytes irradiated with UVA (8 J/cm²) and in non-irradiated cells, respectively, whereas they were 0.364, 0.420, 0.525, 0.540 and 0.545 mmol/g protein when α-tocopherol was added at concentrations of 2.9, 5.9, 8.8, 11.8 and 14.7 IU/ml, respectively. The levels of lipid peroxidation were 20.401 or 5.328 μmol/g [malondialdehyde (MDA)/protein] in keratinocytes irradiated with UVA (8 J/cm²) and in non-irradiated cells, respectively, whereas they were 11.685, 6.544, 5.847, 4.390 and 2.164 μmol/g (MDA/protein) when α-tocopherol was added at concentrations of 2.9, 5.9, 8.8, 11.8 and 14.7 IU/ml, respectively. The levels of ROS were 3,952.17 or 111.87 1/mg protein in keratinocytes irradiated with UVA (8 J/cm²) and in non-irradiated cells, respectively, whereas they were 742.48, 579.36, 358.16, 285.63 and 199.82 1/mg protein when α-tocopherol was added at concentrations of 2.9, 5.9, 8.8, 11.8 and 14.7 IU/ml, respectively. These findings suggested that α-tocopherol protects keratinocytes against UVA irradiation, possibly through increasing the levels of GSH or decreasing the levels of lipid peroxidation and ROS generation.

Hypercholesterolemia: its impact on ischemia-reperfusion injury

Ischemic diseases are a leading cause of death worldwide. It is becoming increasingly appreciated that atherosclerosis is a major cause of ischemia reperfusion. Hypercholesterolemia is a major risk factor for the development of atherosclerosis, and is associated with an increased incidence of ischemia reperfusion. Furthermore, elevated cholesterol levels exacerbate the vascular responses to ischemia-reperfusion, which intensifies the resulting organ dysfunction. One of the underlying features of both ischemia-reperfusion injury and hypercholesterolemia is the proinflammatory and prothrombogenic phenotype invoked in the microvasculature. This is manifested as an endothelial dysfunction, characterized by leukocyte and platelet recruitment, oxidative stress and angiotensin II receptor Type 1a activation. These common pathways of inflammation offer attractive targets for the development of drugs to combat cardiovascular disease and the associated ischemic disorders.

Long-term vitamin E supplementation reduces atherosclerosis and mortality in Ldlr-/- mice, but not when fed Western style diet

OBJECTIVES

Epidemiological and experimental evidence have indicated potential health benefits of vitamin E supplementation on coronary heart disease (CHD), but several clinical trials have reported no benefit from vitamin E supplementation on CHD. We hypothesized that supplemental intake of vitamin E from an early age may prevent or retard the development and progression of atherosclerosis and CHD mortality.

METHODS

To test this hypothesis, 300 Ldlr(-/-) mice were divided into groups receiving Western style high fat/cholesterol (HFHC), moderate fat/cholesterol (MFMC), or low fat/cholesterol (LFLC) diets all containing 50 IU of vitamin E. These dietary groups were further subdivided into four sub-groups (n = 25) receiving their respective diets with no vitamin E supplementation or additionally supplemented with vitamin E (500 IU/kg diet) starting at the early age of 5 wks, or 6 mo, or 12 mo. All mice remained on their assigned diets until age 18 mo. Body weight, health status and survival rate of mice were monitored and recorded. After 18 mo of dietary treatments, mice were sacrificed.

RESULTS

Body weight was the highest in HFHC groups and the lowest in LFLC groups. Plasma concentration of cholesterol and triglycerides was high in all dietary groups, and plasma vitamin E was high in vitamin E supplemented groups. Fifty percent of mice fed Western style HFHC diet and 53% of mice fed MFMC diet survived during the 18 mo, whereas 75% of mice fed LFLC diet survived during the 18 mo dietary treatments. At the age of 18 mo, all the Ldlr(-/-) mice, regardless of dietary treatments, had several advanced atherosclerotic lesions in both aortic root and aortic tree. Within the LFLC groups, those that received vitamin E supplements from age 5 wks up to 18 mo had a significantly higher survival rate of 88% (p = 0.04) and lower mortality (12%) compared to mice that did not receive vitamin E supplements (64%). This lower mortality rate and higher survival rate coincided with significantly (p = 0.03) fewer aortic lesions in the vitamin E supplemented LFLC group (50%) compared to LFLC mice that did not receive vitamin E supplements in their diets (65%). Subjective immunohistochemical evaluation of aortic valves showed that LFLC mice that received vitamin E supplements for 18 mo had less intima media thickness compared to LFLC mice that did not receive vitamin E supplements in their diet. The LFLC mice that were supplemented with vitamin E for 18 mo had the lowest mRNA expression of inflammatory markers such as VCAM-1, MCP-1 and CD36 in samples obtained from lesion and non-lesionareas.

CONCLUSION

In conclusion, 500 mg vitamin E/kg diet in Ldlr(-/-) mice is not effective at reducing mortality and atherosclerosis when the diet contained high or medium levels of fat and cholesterol. However, a relatively low dose and long-term vitamin E supplementation started from an early age is effective in reducing mortality and atherosclerotic lesions in genetically prone Ldlr(-/-) mice fed LFLC diet.