The Effect of Tocotrienol-Rich Fraction on the Expression of Glutathione S-Transferase Isoenzymes in Mice Liver

Abstract

Glutathione S-transferase isoenzymes (GSTs) catalyze the conjugation reaction between glutathione and electrophilic compounds. GSTs are involved in the detoxification of toxic and carcinogenic compounds, thus protecting the body from toxic injuries. Tocotrienols are part of the vitamin E family and is believed to possess potent antioxidant activity. The objective of this study was to determine the effect of increasing doses of tocotrienol rich fraction (TRF) supplementation on liver GSTs gene and protein expression. A total of 30 male ICR white mice were divided into five groups (n=6 for each group) and given treatment for 14 days through oral supplementation. Groups were divided as follows:-three groups administered with TRF at doses of 200, 500 and 1000 mg/kg, respectively, a positive control group administered with 100 mg/kg butylated hydroxyanisole (BHA) and a control group administered with only the vehicle (corn oil). At day 15, the mice were sacrificed and their livers isolated. Total RNA was extracted from the liver and quantitative real-time polymerase chain reaction (qPCR) assays were performed to analyze GSTs gene expression. Total liver protein was also extracted and the protein expression of GSTs was determined by Western blotting. The results showed that TRF oral supplementation caused a significant dose-dependent increase in liver GST isoenzymes gene and protein expression, compared to controls. In conclusion, TRF oral supplementation for 14 days resulted in increased gene and protein expression of GST isoenzymes in mice liver dose-dependently, with the highest expression seen in mice treated with 1000 mg/kg TRF.

Changes in Metabolism and Mitochondrial Bioenergetics during Polyethylene-Induced Osteoclastogenesis

“…This is potentially supported by the finding in this study that the reduction in the number of TRAP-positive osteoclast-like cells following TRF treatment was accompanied by elevated Nrf2 expression. In mice liver, TRF treatment was shown to increase NRF2 gene expression in a dose-dependent manner [ 74 ]. Individual tocotrienol isomers have also been shown to increase Nrf2 expression; for example, δ-tocotrienols reduced oxidative damage in an osteoblastic cell line through the PI3k/AKT-NRF2 pathway [ 75 ].…”

Comparative Studies on the Hepatoprotective Effect of White and Coloured Rice Bran Oil against Acetaminophen‐Induced Oxidative Stress in Mice through Antioxidant‐ and Xenobiotic‐Metabolizing Systems

“…This might be due to higher levels of vitamin E, phytosterols, and plant pigments in CRBO compared with WRBO. Previous reports have shown that oral supplementation of 200 mg/kg BW of tocotrienol rich fraction (one gram contains 41.02, 6.58, 9.96, and 23.8 mg of α -tocotrienol, β -tocotrienol, γ -tocotrienol, and δ -tocotrienol, respectively) caused increased gene and protein expression of hepatic GST isoenzymes in mice [ 48 ]. Oral administration of δ -tocotrienol at 300 mg twice daily for 12 weeks showed greater efficacy than a placebo by decreasing oxidative stress markers including serum ALT, high-sensitivity C-reactive protein, and MDA in patients with nonalcoholic fatty liver disease [ 49 ].…”

Effect of Administration of an Equal Dose of Selected Dietary Chemicals on Nrf2 Nuclear Translocation in the Mouse Liver

“…Blot Analysis. Hepatic Nrf2 nuclear translocation and the expression levels of other proteins of interest in the nuclear and cytoplasmic fractions of the liver were determined using a previously described immunoblotting method [51]. Briefly, 100 μg of liver protein (either from the nuclear or cytosolic fractions) was separated using 15% sodium dodecyl sulfate polyacrylamide gel (SDS-PAGE) electrophoresis.…”