Gamma-tocopherol ameliorates hyperglycemia-induced hepatic inflammation associated with NLRP3 inflammasome in alloxan-induced diabetic mice

BACKGROUND/OBJECTIVES: Hyperglycemia-induced hepatic damage has been recognized as one of the major cause of complications in diabetes. Hepatic complications are associated with inflammation and oxidative stress in diabetes. In this study, we investigated the hypothesis that gamma-tocopherol (GT) supplementation ameliorates NLRP3 inflammasome associated hepatic inflammation in diabetes. MATERIALS/METHODS: Diabetes was induced by the intraperitoneal injection of alloxan (150 mg/kg. BW) in ICR mice. All mice were fed with a control diet (AIN-76A). After diabetes was induced (fasting glucose level ≥ 250 mg/dL), the mice were treated with tocopherol-stripped corn oil or GT-supplemented (35 mg/kg) corn oil, respectively, by gavage for 2 weeks. RESULTS: GT supplementation reduced fasting blood glucose levels in diabetic mice relative to non-treated diabetic mice. Moreover, GT supplementation ameliorated hyperglycemia-induced hepatic damage by regulation of NOD-like receptor protein 3 (NLRP3)-inflammasome associated inflammation represented by NLRP3, apoptosis-associated speck-like protein containing a caspase-recruitment domain, caspase-1, nuclear factor-κB pathway as well as oxidative stress demonstrated by nuclear factor erythroid 2-related factor 2, NAD(P)H dehydrogenase quinone 1, catalase and glutathione-dependent peroxidase in diabetic mice. CONCLUSION: The findings suggested that GT supplementation ameliorated hepatic damage by attenuating inflammation and oxidative stress in alloxan-induced diabetic mice. Taken together, GT could be a beneficial nutrient that can ameliorate inflammatory responses associated with NLRP3 inflammasome in hyperglycemia-induced hepatic damage.

Influência do tempo de armazenamento sobre a concentração de alfa-tocoferol e gama-tocoferol em óleos vegetais / Influence of the storage time on the concentration of alpha-tocopherol and gamma-tocopherol in vegetable oils

O alfa- e o gama-tocoferol estão entre os homólogos da vitamina E, que possui importante papel como antioxidante. As fontes dietéticas mais ricas em vitamina E são os óleos vegetais. Este trabalho avaliou os níveis de alfa- e gama-tocoferol nos óleos de canola, girassol, milho e soja, e averiguou sua variação com o tempo de armazenamento. Os óleos vegetais foram adquiridos nos supermercados da cidade de Natal/RN, e mantidos sob temperatura ambiente e ao abrigo da luz. As análises foram realizadas em diferentes momentos durante o armazenamento (tempo 0 e após 30, 60 e 90 dias). Cromatografia líquida de alta eficiência (CLAE) foi usada para determinar as concentrações dos analitos. A análise estatística foi realizada utilizando-se o teste de variância (ANOVA) e as diferenças foram consideradas estatisticamente significativas quando p < 0,05. Ao final do tempo de armazenamento (90 dias) foi verificada diminuição significativa nos níveis de alfa- e gama-tocoferolde 38,7 % e 36,0 %, no óleo de canola; 42,2 % e 22,2 %, no óleo de soja; 28,3 % e 29,2 %, no óleo de girassol;39,0 % e 17,9 %, no óleo de milho, respectivamente. As concentrações de alfa- e gama-tocoferol nos óleos vegetais reduziram significativamente após armazenamento, sob as condições empregadas no estudo.

The alpha- and gamma-tocopherol are among the homologues of vitamin E which plays a key role as anantioxidant. The richest dietary sources of vitamin E are vegetable oils. This study aimed at evaluating thealpha- and gamma-tocopherol contents in oils from canola, sunflower, corn and soybeans, and to verify their variations after storage time. The vegetable oils were purchased at supermarkets in Natal / RN, and they were keptat room temperature and protected from light. The tests was made at different times during storage (time 0 and after 30, 60 and 90 days). The high performance liquid chromatography (HPLC) was used to determinetheir concentrations. The statistical analysis was performed using analysis of variance (ANOVA) test and thedifferences were considered statistically significant when p < 0.05. By the end of the storage time (90 days), thealpha- and gamma-tocopherol contents showed a significant decrease of 38.7 % and 36.0 % for canola oil; 42.2 %and 22.2 % in soybean oil; 28.3 % and 29.2 % in sunflower oil; 39.0 % and 17.9 % in corn oil, respectively.The concentrations of alpha- and gamma-tocopherol in vegetable oils significantly decreased after the storageperiod under the conditions used in this study.

Relación del colesterol total con la concentración sérica de tocoferoles, un estudio probabilístico en preescolares mexicanos / Relation of total cholesterol in serum tocopherols

Estudios epidemiologicos han demostrado el efecto del estado nutricional de los tocoferoles y el desarrollo de enfermedades cardiovasculares, las cuales son cada vez mas frecuentes en edades tempranas de la vida. Este trabajo relaciona el colesterol total con las concentraciones sericas de tocoferoles en una poblacion de ninos mexicanos, evaluando ademas su estado antioxidante y oxidante. De octubre a diciembre de 2003, se cuantifico en suero a-tocoferol, γ-tocoferol y colesterol total en 1155 niños (12-59 meses) residentes de localidades urbanas y rurales; se evaluo la capacidad antioxidante y el estado oxidante con la produccion de TBARS. Los ninos con cifras de colesterol > 240 mg/dL fue de 577.3 ± 200.8 μg/dL. Sin embargo, cuando se expresaron los tocoferoles en relacion con el colesterol total (μmol/mmol), se observo que los niños con + 1.19), lo que los ubicaba en un adecuado estado nutricional de a-tocoferol, a diferencia del grupo con > 240 mg/dL de colesterol en quienes la relacion fue baja (1.93 ± 0.69). No se observaron diferencias en la capacidad antioxidante del suero, pero si en la produccion de TBARS para los niños con > 200 mg/dL de colesterol. En preescolares los incrementos en el colesterol total limitan la disponibilidad de tocoferoles sericos para los lipidos circulantes, esta condicion a traves del tiempo puede condicionar el desarrollo prematuro de lesiones vasculares mediadas por estres oxidativo.

Epidemiological studies have shown the effect of nutritional status of tocopherols and development of cardiovascular diseases that now are more frequent during early years of life. In this work we evaluated the association between the total cholesterol and serum levels of tocopherols in a population of Mexican children in whom we measured the oxidant status and antioxidant capacity (December 2003). In 1155 children (12-59 months) residents of urban and rural locations we quantified in serum a-tocopherol, γ-tocopherol and total cholesterol; the antioxidant capacity and oxidative status were evaluated with the production of TBARS. Children with serum cholesterol > 240 mg/dL cholesterol recorded an average of 577.3 ± 200.8 μg/dL. However, when tocopherols were expressed in relation to total cholesterol (μmol/mmol) found that children with > 240 mg/dL of cholesterol in whom the relationship was low (1.93 ± 0.69). There were no differences in serum antioxidant capacity, but if in the production of TBARS for children with > 200 mg/dL cholesterol. In preschools the increases in total cholesterol limits the availability of serum tocopherol for circulating lipids, this condition over time could determine the early development of vascular injury mediated by oxidative stress.

Vitamin E: alpha-Tocopherol and the Other Forms of Vitamin E

Vitamin E has been a generic term for all tocopherol and tocotrienol derivatives. The most active form of vitamin E isoforms in vivo is regarded to be alpha-tocopherol which is the only form defined as vitamin E in the US Food and Nutrition Board, causing controversy over setting dietary reference intake (DRI) of vitamin E. However, most of the countries other than the US maintain the original concept that all isoforms are accepted as vitamin E but with different biopotency. The roles of the isoforms of vitamin E other than alpha-tocopherol have received continuous attention. Among them those of gamma-tocopherol and alpha-tocotrienol have been most studied in comparison with alpha-tocopherol, since gamma-tocopherol comprises major form of vitamin E in many plant seeds and those of the both vitamin E have been implicated in unique physiological functions. This review summarizes findings that have led a better understanding of vitamin E absorption, transport, tissue storage and various functions common and specific to vitamin E isoforms focusing alpha- and gamma-tocopherol as well as tocotrienols. It is expected to help redefining vitamin E and setting its DRI for Koreans.

Effects of Gamma-Tocopherol (GT) Supplementation on Vitamin E Concentration in Cigarette Smoke (CS) Exposed Mice

Cigarette smoke (CS) induces oxidative and nitrosative stress to the respiratory tract (RT) via both oxidants contained in CS and by CS-induced activation of RT inflammatory-immune pro-oxidant processes. CS exposure has been associated with reduced levels of plasma micronutrient antioxidants, in part due to an increased utilization and turnover of alpha-tocopherol (AT). It has been suggested that gamma-tocopherol (GT) may have an expanded spectrum of antioxidant activation compared to alpha-tocopherol (AT). In order to investigate effects of high GT supplementation as compared to AT, C57 BL/6 mice were fed control AT (35 mg/kg diet) or high GT (1,000 mg/kg diet) diet for 8-10 weeks and then exposed to 60 mg/m3 CS, 6 hr/day for 3 days. AT and GT levels and their metabolites were measured at endpoints. High GT supplementation significantly reduced AT levels in plasma, liver and lung compared to AT. CS increased levels of AT and GT in plasma and lung of control AT group but decreased GT levels in lung of high GT supplemented group. Moreover, CS significantly decreased GT metabolite, gamma-CEHC. The results suggest that high GT supplementation have selective modulation of concentrations of vitamin E and its metabolite in plasma and lung but not in liver against in vivo CS exposure.

Association between Plasma Tocopherol Levels and Related Factors in Middle-Aged Korean Men

Vitamin E in the body system plays an important role in preventing chronic diseases by decreasing the oxidative stress by free-radicals. However, there are not enough researches on analyzing the primary factors affecting vitamin E levels in the blood in Korean adults. Therefore, the purpose of this research was to examine blood tocopherol levels and the primary factors affecting the status. A complete lifestyle survey was performed on 314 Korean adult men and surveyed their smoking, drinking and exercising habits. The average plasma level of alpha- and gamma-tocopherol showed similar mutual relations with plasma total cholesterol (TC), triglyceride (TG), or low density lipoprotein cholesterol (LDL-C) levels (p < 0.001). Plasma alpha-tocopherol level of the subjects did not show any difference as smoking, drinking and exercising habits changed. However, gamma-tocopherol per TG showed much lower figure in smokers than non smokers (p < 0.05). Amongst diet factors, plasma alpha-tocopherol level showed negative correlations with Vitamin E intake, while gamma-tocopherol level showed positive correlations with Vitamin E intake. Erythrocyte superoxide dismutase (SOD) activity and plasma tocopherol showed negative correlations, and catalase activity and plasma alpha-tocopherol showed positive correlationship. The level of cell DNA damage of lymphocyte and plasma alpha- or gamma-tocopherol showed negative correlations. As a result of this research, the factors that affect Korean adult men's plasma alpha-tocopherol level are plasma TG, LDL-C and cell DNA damage in lymphocyte, while the factors that affect gamma-tocopherol level are plasma TG, LDL-C and vitamin E intake based on multiple regression analysis. These findings implies that the level of different types of tocopherol depends on slightly different factors. A further research is needed on the factors involved in the differentiation of the types of tocopherol.

MEASUREMENT OF PLASMA VITAMIN A AND E IN CHINESE BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY / 营养学报

This paper described a microprocedure for the simultaneous determination of retinol (Vitamin A), alpha and gamma tocopherol (Vitamin E) in plasma by high performance liquid chromatography. A reversed-phase C18 column with precolumn was used. The mobile phase was water in methanol (2:98) and the flow rate was 1.8ml/min. An ultraviolet detector with 300 nm was used. The chromatogram was completed in 12 min and the retinol, alpha and gamma tocopherol were quantitated by the peak area ratio and weight ratio using benzo (e) pyrene as an internal standard. The mean recovery of retinol and alpha tocopherol were 93.9% and 106.9% respectively. The coefficient of variation (CV%) were 5.2 for retinol, 4.8 for gamma tocopherol and 6.3 for alpha tocopherol. In order to assess the possibility of measuring pooled samples instead of individual samples, the value of individuals was compared with the value of the pooled sample. The results showed that the pool values and the mean ? SD of the 25 individuals compared very favourably.6500 blood samples were collected from both sexes and 130 communities of 65 counties. The plasma retinol and tocopherols were analyzed. The average plasma retinol value (X?SD,?g/dl) was 52 ?9.2 for male and 41 ?6.8 for female. The average plasma alpha tocopherol value (X?SD) was 703?108 for male and 735?101 for female. The mean ? SD (?g/dl) of total vitamin E were 750 ? 124 and 776 ?104 respectively for male and female.