Antioxidant Effect Of Α-tocopherol Research Articles

The Impact of Japanese Dietary Patterns on Metabolic Dysfunction-Associated Steatotic Liver Disease and Liver Fibrosis.

This study aimed to investigate the effect of Japanese dietary patterns on metabolic dysfunction-associated steatotic liver disease (MASLD) and liver fibrosis. After excluding factors affecting the diagnosis of hepatic steatosis, 727 adults were analyzed as part of the Health Promotion Project. The dietary patterns of the participants were classified into rice, vegetable, seafood, and sweet based on their daily food intake. Liver stiffness measurements and controlled attenuation parameters were performed using FibroScan. Energy and nutrient intake were calculated using the Brief-type Self-administered Diet History Questionnaire. Univariate and multivariate analyses were used to identify the risk factors for liver fibrosis within the MASLD population. The vegetable group had significantly lower liver fibrosis indicators in the MASLD population than the rice group. The multivariate analysis identified a body mass index ≥ 25 kg/m2 (odds ratio [OR], 1.83; 95% confidence interval [CI], 1.01-1.83; p = 0.047) and HOMA-IR ≥ 1.6 (OR, 3.18; 95% CI, 1.74-5.78; p < 0.001) as risk factors for liver fibrosis, and vegetable group membership was a significant low-risk factor (OR, 0.38; 95% CI, 0.16-0.88; p = 0.023). The multivariate analysis of nutrients in low-risk foods revealed high intake of α-tocopherol (OR, 0.74; 95% CI, 0.56-0.99; p = 0.039) as a significant low-risk factor for liver fibrosis. This study suggests that a vegetable-based Japanese dietary pattern, through the antioxidant effects of α-tocopherol, may help prevent liver fibrosis in MASLD and the development of MASLD.

The effects of the antioxidant α-tocopherol succinate on cisplatin-induced ototoxicity in HEI-OC1 auditory cells

ConclusionD-α-tocopherol succinate significantly reduced a cisplatin-induced hair cell loss in HEI-OC1 cell lines. These effects were mediated by its scavenging activity against reactive oxygen species (ROS) and inhibition of apoptosis. ObjectivesAlpha-tocopherol is a class of methylated phenols, known as fat-soluble antioxidants, and is a different form of vitamin E, which reduces free radicals and acts as an antioxidant. We hypothesized that the antioxidative effect of α-tocopherol could protect against cisplastin-induced cytotoxicity, and thus evaluated its effects on cisplatin-induced ototoxicity in HEI-OC1 auditory cells. MethodsHEI-OC1 cells were pretreated with D-α-tocopherol succinate at a concentration of 10 µM for 24 h, and then exposed to 15 µM cisplatin for 48 h. The cellular viability was measured by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. The intracellular ROS level was measured by using a fluorescent dye, 2′,7′-dichlorofluorescein diacetate (DCFH-DA). Both Annexin V-FITC and propidium iodide (PI) staining were performed to analyze the pattern of apoptosis. The enzymatic activity of caspase-3 was assayed with caspase3/CPP32 fluorometric assay kit. Also, it was assessed by immunoblotting technique of poly-ADP-ribose polymerase (PARP). ResultsPretreatment with 10 µM D-α-tocopherol succinate protected HEI-OC1 auditory cells against cisplatin-induced cytotoxicity. D-α-tocopherol succinate significantly reduced the cisplatin-induced increase in ROS. D-α-tocopherol succinate treatment induced a 15% reduction of ROS and 50% decrease in necrosis and late apoptosis as compared to cisplatin treatment. D-α-tocopherol succinate also decreased the activation of caspase-3 and reduced levels of cleaved poly-ADP-ribose polymerase (PARP).

Antioxidant effect of α-tocopherol and cow urine distillate against oxidative stress induced by heavy metal toxicity in broiler chicken

Forty eight, one week old broiler chicks were randomly divided into eight groups with 6 birds each to study the antioxidant effect of αtocopherol and cow urine distillate (CUD) against oxidative stress induced by heavy metal toxicity of lead acetate and mercuric chloride. Group I served as control receiving standard feed and water ad libitum, whereas, group II, III and IV received in feed lead acetate @ 500 ppm, lead acetate @500 ppm and αtocopherol @ 300 mg/kg with lead acetate @ 500 ppm and an oral supplementation of cow urine distillate @ 1 ml/bird/day respectively. Group V, VI and VII received in feed mercuric chloride @ 50 ppm, mercuric chloride @ 50 ppm with α tocopherol @ 300 mg/kg and mercuric chloride @ 50 ppm and CUD as an oral gavage @ 1 ml/bird/day respectively throughout the experiment. Group VIII served as CUD control receiving oral gavage of CUD @ 1 ml/bird/day. Oxidative stress assessment was carried out in terms of estimation of lipid peroxidation (LPO) in erythrocytes, extent of splenotoxicity and body weight alterations. Ingestion of heavy metals resulted in significant elevation in LPO level, pathological alterations in spleen and other organs with significant reduction in body weight. The extent of pathological lesions in the spleen and the level of LPO were of lesser order in the birds supplemented with α tocopherol and CUD, therefore, it is concluded that α tocopherol and cow urine distillate have a protective effect against heavy metal toxicity in broiler chicken.

Cardiotoxicity induced by dietary oxidized sunflower oil in rats: pro- and antioxidant effects of α-tocopherol.

This study highlighted the pro-oxidative functions of α-tocopherol (αT) on the heart antioxidant system and tissue histopathology of oxidized sunflower oil (OSO)-exposed rats.Four groups of male Wistar rats were fed with different diets: 1) control diet containing FSO (fresh sunflower oil); 2) diet containing 5 % OSO; 3) diet containing 5 % OSO, supplemented with 600 mg αT kg-1; and 4) diet containing 5 % OSO, supplemented with 1200 mg αT kg-1. The hearts were then isolated, and the antioxidant enzymatic activities were assessed. Body weight and catalase (CAT), glutathione peroxidase (GPx) activities significantly decreased in groups fed with OSO, while the lipid peroxidation (LPO) level significantly increased. Administration of OSO with αT (600 mg · kg-1) returned the body weight values and LPO levels to similar values as the control group. The CAT and GPx activities increased but remained significantly lower compared to the control group. In the OSO group with αT (1200 mg · kg-1), the CAT and GPx activities also decreased, while LPO significantly increased. Heart tissue sections obtained from the groups revealed the presence of large areas of necrosis. This study suggested that OSO induced oxidative stress and that administration of a moderate dose of αT restored the antioxidant balance, but that high levels of αT supplementation result in a pro-oxidant effect.

Green tea extract as food antioxidant. Synergism and antagonism with α-tocopherol in vegetable oils and their colloidal systems

The antioxidant effects of α-tocopherol (TOH) in combination with green tea extract (GTE), the green tea polyphenol (−)-epicatechin (EC) or the isomeric (+)-catechin (C), were investigated using different lipid systems based on high linoleic sunflower oil: bulk oil, o/w-emulsion and a phosphatidylcholine-based liposome system. Both polyphenols as well as TOH were efficient antioxidants in all systems when used alone, as detected by the formation of free radicals and conjugated dienes and by oxygen consumption. Strong synergistic effect was found for the combination of TOH and GTE in a methyl linoleate o/w-emulsion and in the pure bulk oil, while only an additive effect was observed in a liposome system. The synergism was already evident for the tendency for radical formation in the bulk oil as detected by electron spin resonance (ESR) spectroscopy. On the contrary, combinations of TOH with either EC or C showed clear synergistic effects in both heterogeneous systems, but antagonistic or additive effects in bulk oil. GTE may accordingly be used to protect both vegetable oils and their emulsions against oxidation through enhancement of the activity of their endogenous antioxidants, while GTE is less efficient in the protection of phospholipids as in liposomes.

Physiochemical and oxidative stability of interesterified structured lipid for soft margarine fat containing Δ5-UPIFAs

Structured lipid (SL) was synthesized from pine nut oil (PNO) and palm stearin (PS). In SL, 8.81% of Δ5-unsaturated polymethylene interrupted fatty acids (Δ5-UPIFAs) were intentionally incorporated into the sn-2 position through acyl migration. The obtained SL contained mostly the β′ form and a wide plastic range with solid fat index of 26.5% at 10°C to 2.29% at 35°C, indicating that the obtained SL (containing zero-trans fatty acid) may be desirable for soft (tub) margarine fat. Subsequently, the antioxidative effects of α-tocopherol (α-TOH), ascorbyl palmitate (AP), quercetin (Qu), and combinations thereof on SL were investigated. Results showed that Qu (500μg/g) showed the most effective antioxidant activity, followed by AP (500μg/g); while α-TOH with any concentrations (100, 200 and 500μg/g) did not show significant protective activity in the obtained SL. Each mixture of AP+Qu and α-TOH+AP+Qu also showed effective antioxidant activity in the obtained SL.

In vitro inhibition of lipid peroxidation in fish by turmeric (Curcuma longa)

The beneficial effects of ∈-3 fatty acids on human health have been well documented. Fish and fish oils are the richest sources of ∈-3 fatty acids. However, due to their high degree of unsaturation, they are highly susceptible to lipid peroxidation. Regular consumption of peroxidised oils may represent a risk factor for the induction and development of atherosclerosis. In view of the above reports, it was considered necessary to study the effects of tumeric on fish lipid peroxidation during standard cooking practices and on time-dependent changes in the peroxidation of fish homogenate. The antioxidant effect of α-tocopherol was also studied to confirm the relevance of the study. The results suggest that turmeric may be considered as a safe, cheap and readily usable antioxidant for food preparations.

Antioxidant and prooxidant roles for β-carotene, α-tocopherol and ascorbic acid in human lung cells

Experiments were conducted to determine the antioxidant and prooxidant effects of β-carotene, α-tocopherol and ascorbic acid on human lung cells at different oxygen (O 2) tensions. Free radical initiator, 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH), was used to induce the cellular damage associated with lipid peroxidation, protein oxidation and DNA breaks. Under hypoxic conditions (0 torr O 2 tension) all compounds produced a concentration-dependent antioxidant effect. Mixtures of the three compounds exhibited greater protective affects than any individual compound. At 143 torr O 2 tension, all compounds exhibited concentration-dependent protective effects against AAPH-induced cellular lipid, protein and DNA damage. At 722 torr O 2 tension, cells exhibited a consistent increase in lipid peroxidation (isoprostane formation), protein oxidation (carbonyl formation) and DNA damage (p53 protein accumulation). β-Carotene (1.5 μ m) produced a prooxidant effect by promoting 12% isoprostane formation. Protein oxidation and DNA damage at 722 torr O 2 tension was not increased by β-carotene; however, the antioxidant effect of β-carotene was attenuated. The antioxidant effects of α-tocopherol, ascorbic acid, and mixtures of the three antioxidant compounds also were reduced by the high O 2 conditions. These results partially substantiate the hypothesis that the antioxidant and prooxidant effects of β-carotene are dependent on O 2 tension and concentration of β-carotene. Such findings may partially explain why selected populations, such as smokers, respond adversely when supplemented with β-carotene.

The antioxidative activity of RRR-α-tocopherol vs RRR-δ-tocopherol in combination with ascorbyl palmitate in cooked, minced turkey

RRR-α-tocopherol and RRR-δ-tocopheroI (100 or 200 ppm) had similar and significantly better antioxidative effects compared to ascorbyl palmitate (200 ppm) in turkey meat balls during storage at 5 °C for up to 9 days, as determined by measurement of thiobarbituric acid reactive substances (TBARS) and by static head space detection of hexanal. The antioxidative effect of α-tocopherol at 100 ppm was, measured as a reduction of head space hexanal, significantly enhanced by ascorbyl palmitate (200 ppm), resulting in a further 50% reduction compared to δ-tocopherol. At the 200-ppm level, only the antioxidative activity of α-tocopherol was enhanced significantly by ascorbyl palmitate (200 ppm), in contrast to the effect on the antioxidative activity of δ-tocopherol (200 ppm). The antioxidative activity obtained by α-tocopherol at the 100-ppm level in combination with ascorbyl palmitate (200 ppm) was similar to the effect obtained by α-tocopherol at the 200-ppm level in combination with ascorbyl palmitate (200 ppm) measured as head space hexanal. Ascorbyl palmitate was in all storage experiments depleted in the product at a rate which appeared to be independent of the presence of tocopherols. Of the tocopherol homologues, α-tocopherol was most affected by the presence of ascorbyl palmitate, and the concentration of α-tocopherol was found to decrease during storage in the absence of ascorbyl palmitate, in contrast to when ascorbyl palmitate was present. A similar effect of ascorbyl palmitate was less evident for δ-tocopherol and for γ-tocopherol in a natural mixture of the tocopherol homologues added to turkey meat balls.

Enzymic and autoxidation of lipids in low fat foods: model of linoleic acid in emulsified triolein and vegetable oils

To evaluate problems in novel foods with reduced fat content the linoleic acid model systems used in our previous study were applied to high oleic sunflower oil, triolein and stripped corn oil, in the presence or absence of added α-tocopherol. Initial rates of oxygen uptake by enzymic oxidation depended on the emulsion concentrations and not on their fatty acid compositions. Using static headspace gas chromatography a significant difference in the release of hexanal was detected between emulsions rich in either linoleate or oleate. The higher the linoleate content of the emulsion, the higher the conjugated diene absorbance and the amounts of hexanal produced. In the presence of α-tocopherol the diene absorbance was increased and the hexanal yields decreased, indicating that α-tocopherol retarded the decomposition of hydroperoxides. On the other hand, the antioxidant effects of α-tocopherol were gradually lost during autoxidation tests at 60°C. Therefore, large differences were observed in the amounts and compositions of volatile compounds between emulsions rich in either oleate or linoleate. Lipid concentration, type of lipids and presence of antioxidants are important factors in the oxidative formation of volatile compounds in our models. These factors are expected to impact on the flavour of low fat foods.

Synergism of Ascorbyl Stearate with the Antioxidative Effect of α-Tocopherol

The antioxidative effect of ascorbyl stearate (AS) and its synergistic effect with α-tocopherol (α-Toc) in the case of air oxidation of purified trilinolein (TL) and triolein (TO) were examined, and free ascorbic acid (AA) was used for comparison. Samples were oxidized by introducing oxygen at 75°C into a dark glass tube, then oxidized samples were taken at various times and their peroxide values (POV) were measured. The time required for POV to reach 500 (meq/kg) was regarded as the induction period.The following results were obtained.(1) When 0.01-2.0mM/kg of AS was added to TL or TO, and the oxidation test was carried out, no antioxidative effect was observed.(2) TL containing 1.0mM/kg of α-Toc was supplemented with 0.01-2.0mM/kg of AS and subjected to the oxidation test. A synergistic effect of AS was clearly observed; the induction period was prolonged 2.5-3 times compared with α-Toc alone. A similar effect was observed with TO containing 0.1mM/kg of α-Toc, when 0.01-0.3mM/kg of AS was added.(3) An optimum concentration of AS was observed as a synergist with α-Toc; higher levels of As did not increase the effect any further. The effect of AS resembled that of AA.

Intermembrane transfer and antioxidant action of α-tocopherol in liposomes

Intermembrane transfer and exchange of tocopherol are not well understood. To study this we tested the ability of α-tocopherol containing unilamellar donor liposomes to inhibit the accumulation of lipid peroxidation products in acceptor liposomes. With molar ratios of α-tocopherol:phospholipids from 1:100 to 1:1000 in donor liposomes prepared by sonication of lipid dispersions, α-tocopherol was incorporated into both monolayers and was homogenously distributed in monomeric form without forming clusters in the liposomes. Concentrations of α-tocopherol which completely prevented the peroxidation of lipids were chosen for donor liposomes. Hence inhibition of lipid peroxidation in mixtures of donor and acceptor liposomes was determined by the antioxidant effect of α-tocopherol in acceptor liposomes which resulted from intermembrane transfer and exchange of α-tocopherol. Evidence was obtained that this was not due to fusion of donor with acceptor liposomes. The efficiency of the “intermembrane” antioxidant action of tocopherol was more pronounced when donor liposomes contained unsaturated phospholipids, indicating that the presence of unsaturated fatty acids in the outer monolayer phospholipids facilitates intermembrane tocopherol exchange.

Air Oxidation of Trilinolein and the Antioxidative Effect of α-Tocopherol and Synergism of Ascorbic Acid

To examine the autoxidation of unsaturated triglycerides, experiments were carried out on purified trilinolein (TL), by introducing oxygen at 75°C into an apparatus similar to that employed previously. Methyl linoleate (ML) prepared from the same source was used for comparison. Samples were taken at various oxidation times, and several chemical constants such as peroxide value (POV), thiobarbituric acid value (TBAV), etc. were measured. The IR and UV absorption spectra were also examined. Further, the antioxidative effect of α-tocopherol (α-Toc) and the synergism of ascorbic acid (AA) were studied. α-Toc and AA (3mM/kg) were added TL, and the residual amounts of them in the course of oxidation were followed by high performance liquid chromatography. The relation between the decrease of residual α-Toc and AA and the increase of POV of TL was examined.The results obtained were as follows. The induction period of oxidation was much shorter in TL than in ML. The rate of oxidation or decomposition of peroxides was faster in TL than in ML after the induction periods. The maximum TBAV of TL was found to be about 1/3 that of ML. The antioxidative effect of α-Toc and the synergistic effect of AA were clearly observed in both TL and ML. It was observed that α-Toc and AA decreased more gradually when both were present than either one alone. The results indicate that α-Toc and AA acted as mutually protective substances, and when both disappeared at nearly the same time, POV increased rapidly.

Antioxidant Effects of α-Tocopherol and Ascorbate in Liposomes Exposed to Nitrogen Dioxide

AbstractThis study investigated the rate constants of α-tocopherol and ascorbate oxidation by nitrogen dioxide in the presence of saturated and polyunsaturated phospholipids, and further evaluated whether the oxidation rate of these vitamins was sufficient to protect membranes from nitrogen dioxide-induced peroxidation. Liposomes of unsat-urated phospholipids containing vitamin E permit exposure to nitrogen dioxide and quantitation of vitamin E oxidation. Liposomes made of l-α-dipalmitoyl phosphatidyl-choline containing α-tocopherol in the bilayer at a ratio of 1.50 (α-tocopherol: palmitic acid) revealed a second-order rate constant for α-tocopherol oxidation of 8.9 × 10−-2 M−1 s−1. Under the same conditions with liposomes made from l-α-dilinoleoyl phosphatidylcholine, the second-order rate constant was 4.9 × 10−-1M−1s−1. α-Tocopherol quinone was the product of the nitrogen dioxide induced α-tocopherol oxidation. Ascorbate (50 μM) in the presence of l-α-dilinoleoyl phosphatidylcholine liposomes was oxidiz...

Air Oxidation of Triolein and the Antioxidative Effect of α-Tocopherol and Synergism of Ascorbic Acid

To examine the autoxidation of unsaturated triglycerides, experiments were carried out on purified trilinolein (TL), by introducing oxygen at 75°C into an apparatus similar to that employed previously. Methyl linoleate (ML) prepared from the same source was used for comparison. Samples were taken at various oxidation times, and several chemical constants such as peroxide value (POV), thiobarbituric acid value (TBAV), etc. were measured. The IR and UV absorption spectra were also examined. Further, the antioxidative effect of α-tocopherol (α-Toc) and the synergism of ascorbic acid (AA) were studied. α-Toc and AA (3mM/kg) were added TL, and the residual amounts of them in the course of oxidation were followed by high performance liquid chromatography. The relation between the decrease of residual α-Toc and AA and the increase of POV of TL was examined.The results obtained were as follows. The induction period of oxidation was much shorter in TL than in ML. The rate of oxidation or decomposition of peroxides was faster in TL than in ML after the induction periods. The maximum TBAV of TL was found to be about 1/3 that of ML. The antioxidative effect of α-Toc and the synergistic effect of AA were clearly observed in both TL and ML. It was observed that α-Toc and AA decreased more gradually when both were present than either one alone. The results indicate that α-Toc and AA acted as mutually protective substances, and when both disappeared at nearly the same time, POV increased rapidly.

Oxidation of Methyl Linoleate and the Influence of Antioxdants. IV. On the Antioxidant Action of α-Tocopherol and Synergism of Organic Acids

In a series of the studies, the antioxidant effect of D, L-α-tocopherol and the synergistic effects of some kinds of organic acids on the oxidation of methyl linoleate (ML) with oxygen were reported in this paper. Samples and experimental conditions were same as those described in the previous paper. Oxygen was passed through purified ML with or without the antioxidant and the synergists, then the samples obtained were estimated for peroxide value. Antioxidant effect of α-tocopherol on the oxidation at 105°was shown little in the absence of the synergist, but was remarkable in the presence of ascorbic acid or citric acid. The effect of α-tocopherol on the oxidation at 70°was clearly observed even without any synergist, but the addition of it increased markedly the antioxidant offect of α-tocopherol. The effect of α-tocopherol was compared with that of butyl hydroxy anisol (BHA), which had been reported in the previous paper. It was shown that the effect of BHA was more active than that of α-tocopherol ; even a half equivalent of BHA was more effective than α-tocopherol on the oxidation at 70°. Sixteen kinds of organic acids and esters were examined for the synergistic effect with α-tocopherol and eight of them were found to be effective in preventing oxidatien of methyl linoleate ; D, L-malic, L-tartaric, oxaloacetic, malonic, citric, L-ascorbic, and D, L-gliceric acids and diethyl malate were effective ; succinic (weak +), tartronic, propionic, lactic, β-hydroxybutyric, and pyruvic acids, gluconolactone, and triethyl citrate were ineffective. The mechanism of the synergistic action of these organic acids seemed to be complicated, but the synergist was assumed to act as a hydrogen donor to α-tocopherol (or its oxidation products).