Recent studies suggest that reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) may exert beneficial effects on health. Therefore this study evaluated the effects of H2O2 and gamma-tocotrienol (GTT), an antioxidant, on D-[2-3H]Glucose uptake by myotubes compared to insulin. Results showed that H2O2 and insulin significantly increased D-[2-3H]Glucose uptake. This was associated with an increased in Vmax but Michaelis constant (Km) of the transport system remained unchanged indicating that an increase in amount, rather than affinity, of the glucose transporter was involved in the process. Western blot studies confirmed that H2O2 increased the expressions of insulin sensitive glucose transporter, GLUT4 and also hexokinase (an enzyme which phosphorylates glucose and indirectly stimulates glucose uptake by cells). H2O2 and insulin also stimulated increased in PPAR-γ and IRS-1, which are proteins of the insulin transduction pathway. The present data however showed that GTT did not exert any effect on glucose uptake. Thus, the study showed that H2O2 mimicked insulin action in stimulating glucose uptake in myotube cells by influencing the insulin signaling pathway.
Tocopherols and tocotrienols have been shown in previous studies to protect neurons from oxidative injuries, especially from hydrogen peroxide (H2O2) and buthionine sulfoximine (BSO) induced oxidative stress. In this study, we compared two vitamin E isomers, γ-tocotrienol (GTT) and α-tocopherol (ATF) in their neuroprotective effects against H2O2-induced apoptosis in primary rat cortical neurons and human neuroblastoma cell line SH-SY5Y. Cytotoxicity screening of H2O2, GTT and ATF was done to determine the IC50 levels. To screen for neuroprotective effects, cortical neurons and SH-SY5Y cell cultures were pre-incubated with GTT or ATF, respectively at different concentrations for 1 hour before concurrent treatment of H2O2 at IC50. Results of these treatments were compared to cells treated with H2O2 only and control cells. Cytotoxicology screening showed that IC50 of H2O2 for cortical neuron is at 50 μM while SH-SY5Y have higher IC50 of 100 μM. GTT is cytotoxic to cortical neurons at ≥50 μM and SH-SY5Y at ≥100 μM while ATF did not show any toxicity within the range of concentration tested (1-750 μM). Results from neuroprotection screening showed that GTT and ATF were able to protect both cortical neurons and SH-SY5Y from H2O2-induced oxidative stress at concetration of ≤10 μM. Cellular uptake of GTT is higher in both cortical neurons and SH-SY5Y as compared to ATF when both cortical neuron and SH-SY5Y were incubated with 10 μM GTT or ATF, respectively for 24 hour. Although primary rat cortical neurons and human neuroblastoma SH-SY5Y were different culture system, the effects of GTT and ATF are similar in both H2O2 –induced culture which strongly suggest that both GTT and ATF act as free radical scavenger to exert their neuroprotective effects.
ABSTRACT
Metabolic footprinting involves the determination of metabolites excreted or secreted by the cells.
This study aimed to identify the differential extracellular metabolites in colorectal cancer (CRC)
cells for the determination of molecular changes that occur as CRC progresses. CRC cells at
different stages ie; SW 1116 (stage A), HT 29 and SW 480 (stage B), HCT 15 and DLD-1 (stage
C), and HCT 116 (stage D) were grown in culture. The media in which the cells were grown are
subjected to metabolomics profiling using Liquid Chromatography Mass SpectrometryQuadrupole Time of Flight (LC/MS Q-TOF). Statistical and metabolic pathway analysis was
performed using Metaboanalyst software and identification of metabolites was determined by the
METLIN database. A total of 27 differential extracellular metabolites were identified in CRC cells
of different stages compared to stage A cells. Data from the Partial least squares-discriminant
analysis (PLS-DA) score plot shows a clear separation between CRC cells of different stages with
a few overlaps between stage B and C. Further analysis using variable importance in projection
(VIP) revealed 14 differential extracellular metabolites that were most significant in differentiating
CRC cells of the advanced stages from stage A which are 5-hydroxy-L-tryptophan,
indoleacetaldehyde, 4,5-dimethylthiazole, 8-oxodiacetoxyscirpenol, bisnorbiotin, 5-amino-6-
(5'phosphoribosylamino) uracil, glyceryl 5-hydroxydecanoate, sphinganine, 8,8-diethoxy-2,6-
dimethyl-2-octanol, l-cystine, thiamine acetic acid, phytosphingosine, PE
(20:4(5Z,8Z,11Z,14Z)/22:6(4Z,7Z,10Z,13Z,16Z,19Z)), N-(2R-hydroxypentacosano-yl)-2Samino-1,3S,4R-octadecanetriol. The different expressions of metabolites may indicate altered
metabolic pathways in the more advanced CRC cells compared to stage A. This study highlights
the importance of conducting both metabolomics profiling of extracellular and intracellular to
generate a more complete understanding on the molecular changes that occur as CRC progresses
Vitamin E is composed of various subfamilies that include tocopherols and tocotrienols. These compounds have antioxidant properties but differ in structure, dietary source and potency. In this study we evaluated the efficacy of alpha-tocopherol as an antioxidant and its role in wound closure in normal and streptozotocin-induced diabetic rats. The healing of 6 cm linear incisions created on the back of each male Sprague-Dawley rat (250-300 g) was monitored by measuring the length of the wounds daily. The rats were divided into two categories; normal and streptozotocin-induced diabetic rats. For each category, the animals were further divided into two groups; those untreated and those receiving 200 mg/kg bodyweight alpha-tocopherols daily by oral gavage. All rats were fed standard food and water ad libitum. Blood samples were taken at 0, 5 and 10 days after the wounds were created for the determination of malondialdehyde levels and red cell superoxide dismutase, catalase and glutathione peroxidase activities. The results showed that alpha-tocopherol reduced plasma malondialdehyde levels, increased glutathione peroxidase activity and accelerated the rate of wound closure in treated rats.