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Journal of Food Protection May 2023Food safety is a top priority for the protection of infants and young children. Ochratoxin A (OTA) is an emerging concern due to its high toxicity and occurrence in a...
Food safety is a top priority for the protection of infants and young children. Ochratoxin A (OTA) is an emerging concern due to its high toxicity and occurrence in a wide range of agricultural crops and their derived food products including those foods and snacks destined for infants and young children. OTA is considered as a possible human carcinogen, and its main target organ is the kidney. The objective of this study was to investigate the protective effect of α-tocopherol against oxidative stress induced by OTA using human proximal tubule epithelial cells (HK-2). OTA showed dose-dependent increase in cytotoxicity (IC = 161 nM, p < 0.05) at 48 h, while treatment up to 2 mM α-tocopherol did not change cell viability. Levels of the reduced form of glutathione (GSH) were decreased with α-tocopherol treatment, although the ratio of the oxidative form (GSSG) to GSH remained the same. Among several genes associated with oxidative stress, expression of superoxide dismutase 1 (SOD1), catalase (CAT), glutathione reductase (GSR), and kidney injury molecule-1 (KIM-1) were significantly up-regulated by OTA treatment. CAT and GSR showed decreased expression at 0.5-2 mM α-tocopherol and OTA at IC value, KIM-1 was decreased at 0.5 mM α-tocopherol and OTA at IC value, and nuclear factor erythroid 2-related factor 2 (Nrf2) was decreased at 0.5-1 mM α-tocopherol and OTA at IC value. In addition, the levels of malondialdehyde (MDA) were increased significantly by OTA while significantly decreased by α-tocopherol. The results show that α-tocopherol may alleviate potential OTA-induced renal damage and oxidative stress through reducing cytotoxicity and enhancing the antioxidant defense systems.
Topics: Child; Humans; Child, Preschool; alpha-Tocopherol; Ochratoxins; Kidney; Oxidative Stress; Glutathione; Cell Line; Epithelial Cells
PubMed: 36997025
DOI: 10.1016/j.jfp.2023.100082 -
Vitamins and Hormones 2007alpha-Tocopherol, which belongs to the vitamin E group of compounds, is a lipophilic antioxidant that has a number of functions in plants. Synthesized from homogentisic... (Review)
Review
alpha-Tocopherol, which belongs to the vitamin E group of compounds, is a lipophilic antioxidant that has a number of functions in plants. Synthesized from homogentisic acid and isopentenyl diphosphate in the chloroplast envelope, alpha-tocopherol is essential to maintain the integrity of photosynthetic membranes and plays a major role in photo- and antioxidant protection. alpha-Tocopherol scavenges lipid peroxy radicals, thereby preventing the propagation of lipid peroxidation, and protects lipids and other membrane components by physically quenching and reacting chemically with singlet oxygen. Moreover, given that alpha-tocopherol increases membrane rigidity, its concentration, together with that of the other membrane components, may be regulated to afford adequate fluidity for membrane function. Furthermore, recent studies on tocopherol-deficient plants indicate that alpha-tocopherol may affect cellular signaling in plants. Evidence thus far indicates that the effects of this compound in plant cellular signaling may be linked to the control of redox homeostasis. alpha-Tocopherol may influence cellular signaling by controlling the propagation of lipid peroxidation in chloroplasts, therefore modulating the formation of oxylipins such as the phytohormone jasmonic acid.
Topics: Antioxidants; Plants; Signal Transduction; alpha-Tocopherol
PubMed: 17628182
DOI: 10.1016/S0083-6729(07)76014-4 -
Molecular Aspects of Medicine 2007Natural vitamin E consists of four different tocopherol and four different tocotrienol homologues (alpha,beta, gamma, delta) that all have antioxidant activity. However,... (Review)
Review
Natural vitamin E consists of four different tocopherol and four different tocotrienol homologues (alpha,beta, gamma, delta) that all have antioxidant activity. However, recent data indicate that the different vitamin E homologues also have biological activity unrelated to their antioxidant activity. In this review, we discuss the anti-inflammatory properties of the two major forms of vitamin E, alpha-tocopherol (alphaT) and gamma-tocopherol (gammaT), and discuss the potential molecular mechanisms involved in these effects. While both tocopherols exhibit anti-inflammatory activity in vitro and in vivo, supplementation with mixed (gammaT-enriched) tocopherols seems to be more potent than supplementation with alphaT alone. This may explain the mostly negative outcomes of the recent large-scale interventional chronic disease prevention trials with alphaT only and thus warrants further investigation.
Topics: Animals; Anti-Inflammatory Agents; Humans; alpha-Tocopherol; gamma-Tocopherol
PubMed: 17316780
DOI: 10.1016/j.mam.2007.01.003 -
Reproductive Biology Mar 2022Extravillous trophoblasts (EVTs) are the main participants in the process of placentation, an early process critical for placental growth and function involving an...
Extravillous trophoblasts (EVTs) are the main participants in the process of placentation, an early process critical for placental growth and function involving an adequate invasion and complete remodelling of the maternal spiral arteries during early pregnancy. An increase in oxidative stress during pregnancy is associated with the onset and progression of several pregnancy disorders, including preeclampsia and gestational diabetes mellitus and it also occurs due to exposure of pregnant women to some xenobiotics (eg. alcohol). This study aimed to investigate how oxidative stress affects EVTs, and the ability of several distinct antioxidant agents to prevent these changes. For this, we exposed HTR8/SVneo cells to tert-butylhydroperoxide (0.5 μM; 24 h), which was able to increase lipid peroxidation and protein carbonyl levels. Under these conditions, there was a decrease in proliferation rates, culture growth, migratory and angiogenic capacities and an increase in the apoptosis rates. The antiproliferative effect of TBH was supressed by simultaneous treatment of the cells with α-tocopherol, but other antioxidants (vitamin C, allopurinol, apocynin, N-acetylcysteine, quercetin and resveratrol) were ineffective. α-tocopherol was also able to abolish the effect of TBH on lipid peroxidation and protein carbonyl levels. Overall, our results show that oxidative stress interferes with EVT characteristics essential for the placentation process, which may contribute to the association between oxidative stress and pregnancy disorders. Our results also show that the nature of the in vitro model of oxidative stress-induction is an important determinant of the cellular consequences of oxidative stress and, therefore, of the efficacy of antioxidants.
Topics: Cell Line; Cell Movement; Female; Humans; Oxidative Stress; Placenta; Placentation; Pregnancy; Pregnancy Trimester, First; Trophoblasts; alpha-Tocopherol
PubMed: 35016050
DOI: 10.1016/j.repbio.2022.100602 -
Vitamins and Hormones 2007The addition products of alpha-tocopherol with lipid-derived free radicals have been reviewed. Free radical scavenging reactions of alpha-tocopherol take place via the... (Review)
Review
The addition products of alpha-tocopherol with lipid-derived free radicals have been reviewed. Free radical scavenging reactions of alpha-tocopherol take place via the alpha-tocopheroxyl radical as an intermediate. If a suitable free radical is present, an addition product can be formed from the coupling of the free radical with the alpha-tocopheroxyl radical. The addition products of alpha-tocopherol with lipid-peroxyl radicals are 8a-(lipid-dioxy)-alpha-tocopherones, which are hydrolyzed to alpha-tocopherylquinone. On the other hand, the carbon-centered radicals of lipids prefer to react with the phenoxyl radical of alpha-tocopherol to form 6-O-lipid-alpha-tocopherol under anaerobic conditions. The addition products of alpha-tocopherol with peroxyl radicals (epoxylinoleoyl-peroxyl radicals) produced from cholesteryl ester and phosphatidylcholine were detected in the peroxidized human plasma using a high-sensitive HPLC procedure with postcolumn reduction and electrochemical detection. Thus, the formation of these addition products provides us with much information on the antioxidant function of vitamin E in biological systems.
Topics: Antioxidants; Free Radicals; Humans; Lipid Metabolism; Lipids; Oxidation-Reduction; Reactive Oxygen Species; alpha-Tocopherol
PubMed: 17628179
DOI: 10.1016/S0083-6729(07)76011-9 -
Environmental Science and Pollution... Aug 2023The source of energy for all photoautotrophic organisms is light, which is absorbed by photosynthetic processes and used to transform carbon dioxide and HO into organic...
The source of energy for all photoautotrophic organisms is light, which is absorbed by photosynthetic processes and used to transform carbon dioxide and HO into organic molecules. The majority of UV-B light (280 to 320 nm) is absorbed by stratospheric ozone layer, although some of it does reach at the Earth's surface. Because of the sedentary lifestyle of plants, this form of abiotic stress is unavoidable and can induce growth and even cell death. Ten-day-old calli generated from mature Kirik wheat embryos were subjected to UV-B radiation for 0, 2, 4, and 6 h to examine the function of exogenous α-tocopherol, a lipophilic antioxidant, in wheat tolerance to UV-B radiation stress. The calli were then moved to a callus medium containing α-tocopherol (0, 50, and 100 mg/l) and cultivated there for 20 days after being subjected to UV-B stress. For plant regeneration, embryogenic calli were put on a medium for plant regeneration after 30 days. The findings of this investigation demonstrated that an increase in UV-B exposure period resulted in a substantial drop in the relative growth rate of callus, the rate of embryogenic callus, the rate of responding embryogenic callus, and the number of plants in each explant. On the other hand, with the application of α-tocopherol, all these parameters improved, and the best result was observed in the application of 100 mg/l of α-tocopherol in terms of plant regeneration under UV-B stress.
Topics: alpha-Tocopherol; Triticum; Bread; Antioxidants
PubMed: 37452252
DOI: 10.1007/s11356-023-28768-3 -
Journal of Nutritional Science and... 2018To elucidate the characteristics of γ-tocopherol metabolism, serum concentrations of α- and γ-tocopherol, and urinary excretion of their metabolites after ingestion... (Comparative Study)
Comparative Study
To elucidate the characteristics of γ-tocopherol metabolism, serum concentrations of α- and γ-tocopherol, and urinary excretion of their metabolites after ingestion of α- or γ-tocopherol, major isoforms in our diet, were compared. Six healthy Japanese women (age 22.7±1.7 y old, BMI 21.4±0.9) ingested 134 mg of α- or γ-tocopherol, and blood and urine were collected until 72 h later. After α-tocopherol intake, the serum concentration of α-tocopherol increased at 12-24 h, and urinary excretion of 2,5,7,8-tetramethyl-2(2'-carboxyethyl)-6-hydroxychroman (α-CEHC), an α-tocopherol metabolite, increased at 12-36 h. However, after γ-tocopherol intake, the serum concentration of γ-tocopherol increased at 6-12 h, and excretion of 2,7,8-trimethyl-2(2'-carboxyethyl)-6-hydroxychroman (γ-CEHC), a γ-tocopherol metabolite, increased at 3-12 h. The area under the curve from 0 to 72 h and serum maximal concentration of γ-tocopherol were lower than those of α-tocopherol. The time to maximal concentration of γ-tocopherol was faster than that of α-tocopherol. The ratio of urinary excretion of carboxyethyl-hydroxychroman to tocopherol intake was 2.9% for α-CEHC and 7.7% for γ-CEHC. These results revealed that γ-tocopherol is metabolized faster than α-tocopherol in healthy young women.
Topics: Adult; Chromans; Chromatography, High Pressure Liquid; Diet; Eating; Female; Humans; Japan; Nutritional Status; Propionates; Young Adult; alpha-Tocopherol; gamma-Tocopherol
PubMed: 30606962
DOI: 10.3177/jnsv.64.399 -
Annals of the New York Academy of... Dec 2004Clinical practice in dermatology indicates that alpha-tocopherol acetate is beneficial in xerosis, hyperkeratosis, asteatotic eczema, atopic dermatitis, superficial... (Review)
Review
Clinical practice in dermatology indicates that alpha-tocopherol acetate is beneficial in xerosis, hyperkeratosis, asteatotic eczema, atopic dermatitis, superficial burns, cutaneous ulcers, onychoschizia and, in general, skin diseases in which an inflammatory process is activated. The positive effect results from the combination of biological activity, the absence of adverse reactions, and the physical effect of the alpha-tocopherol acetate oil. The viscosity of this oil in bulk phase accounts for a remarkable moisturizing effect and minimization of transepidermal water loss. This effect combines well with the antioxidant capacity of alpha-tocopherol released from the ester, and the recently emerging effect on reprogramming of gene expression.
Topics: Administration, Topical; Antioxidants; Dermatitis; Humans; MEDLINE; Oils; Skin Diseases; Tocopherols; Viscosity; alpha-Tocopherol
PubMed: 15753192
DOI: 10.1196/annals.1331.069 -
Biological Chemistry Jul 2004Several genes are regulated by tocopherols which can be categorized, based on their function, into five groups: genes that are involved in the uptake and degradation of... (Review)
Review
Several genes are regulated by tocopherols which can be categorized, based on their function, into five groups: genes that are involved in the uptake and degradation of tocopherols (Group 1) include alpha-tocopherol transfer protein (alpha-TTP) and cytochrome P450 (CYP3A); genes that are associated with lipid uptake and atherosclerosis (Group 2) include CD36, SR-BI and SR-AI/II. Genes that modulate the expression of extracellular proteins (Group 3) include tropomyosin, collagen(alpha1), MMP-1, MMP-19 and connective tissue growth factor (CTGF). Genes that are related to inflammation, cell adhesion and platelet aggregation (Group 4) include E-selectin, ICAM-1, integrins, glycoprotein IIb, II-2, IL-4 and IL-beta. Group 5 comprises genes coding for proteins involved in cell signaling and cell cycle regulation and consists of PPAR-gamma, cyclin D1, cyclin E, Bcl2-L1, p27 and CD95 (Apo-1/Fas ligand). The expression of P27, Bcl2, alpha-TTP, CYP3A, tropomyosin, II-2, PPAR-gamma, and CTGF appears to be up-regulated by one or more tocopherols whereas all other listed genes are down-regulated. Several mechanisms may underlie tocopherol-dependent gene regulation. In some cases protein kinase C has been implicated due to its deactivation by alpha-tocopherol and its participation in the regulation of a number of transcription factors (NF-kappaB, AP-1). In other cases a direct involvement of PXR/RXR has been documented. The antioxidant responsive element (ARE) appears in some cases to be involved as well as the transforming growth factor beta responsive element (TGF-beta-RE). This heterogeneity of mediators of tocopherol action suggests the need of a common element that could be a receptor or a co-receptor, able to interact with tocopherol and with transcription factors directed toward specific regions of promoter sequences of sensitive genes. Here we review recent results of the search for molecular mechanisms underpinning the central signaling mechanism.
Topics: Animals; Cell Proliferation; Gene Expression Regulation; Humans; Signal Transduction; Transcription, Genetic; alpha-Tocopherol
PubMed: 15318806
DOI: 10.1515/BC.2004.072 -
Biochemistry. Biokhimiia Jan 2004Vitamin E acts as an antioxidant and stabilizer of membranes. Other functions of vitamin E unrelated to its effects on membranes are emerging. Vitamin E partitions into... (Review)
Review
Vitamin E acts as an antioxidant and stabilizer of membranes. Other functions of vitamin E unrelated to its effects on membranes are emerging. Vitamin E partitions into the lipid bilayer matrix of membranes. It orients perpendicularly to the plane of the membrane with the hydroxyl group pointing to the lipid-water interface. The vitamin is not randomly distributed in the plane of the membrane but tends to form clusters. These clusters appear to be composed of vitamin E and phosphatidylcholine in a stoichiometry of about one vitamin E per 10 phospholipid molecules. Vitamin E partitions into domains of phosphatidylcholine in model membranes formed from mixtures of phosphatidylcholine and phosphatidylethanolamine irrespective of whether the phosphatidylcholine is in the fluid or gel phase. The creation of domains enriched in vitamin E in membranes is not consistent with an antioxidant function and effects on membrane structure and stability indicate other roles of the vitamin.
Topics: Cell Membrane; Phospholipids; Temperature; alpha-Tocopherol
PubMed: 14972019
DOI: 10.1023/b:biry.0000016352.88061.02