Tocotrienols are powerful chain breaking antioxidant. Moreover, they are now known to exhibit various non-antioxidant properties such as anti-cancer, neuroprotective and hypocholesterolemic functions. This study was undertaken to investigate the anti-inflammatory effects of tocotrienol-rich fraction (TRF) and individual tocotrienol isoforms namely delta-, gamma-, and alpha-tocotrienol on lipopolysaccharide-stimulated RAW264.7 macrophages. The widely studied vitamin E form, alpha-tocopherol, was used as comparison. Stimulation of RAW264.7 with lipopolysaccharide induced the release of various inflammatory markers. 10 mcirog/ml of TRF and all tocotrienol isoforms significantly inhibited the production of interleukin-6 and nitric oxide. However, only alpha-tocotrienol demonstrated a significant effect in lowering tumor necrosis factor-alpha production. Besides, TRF and all tocotrienol isoforms except gamma-tocotrienol reduced prostaglandin E(2) release. It was accompanied by the down-regulation of cyclooxygenase-2 gene expression by all vitamin E forms except alpha-tocopherol. Collectively, the data suggested that tocotrienols are better anti-inflammatory agents than alpha-tocopherol and the most effective form is delta-tocotrienol.
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Chronic treatment with tocotrienol, an isoform of vitamin E, prevents intracerebroventricular streptozotocin-induced cognitive impairment and oxidative-nitrosative stress in rats
Tiwari V, Kuhad A, Bishnoi M, Chopra K.
Pharmacol Biochem Behav. 2009 Aug;93(2):183-9. Epub 2009 May 21.
Intracerebroventricular (ICV) streptozotocin (STZ) has been shown to cause cognitive impairment, which is associated with increased oxidative stress in the brain of rats. In the present study, we investigated the effect of both the isoforms of vitamin E, alpha-tocopherol and tocotrienol against ICV STZ-induced cognitive impairment and oxidative-nitrosative stress in rats. Adult male Wistar rats were injected with ICV STZ (3 mg/kg) bilaterally. The learning and memory behavior was assessed using Morris water maze and elevated plus maze. The rats were sacrificed on day 21 and parameters of oxidative stress, nitrite levels and acetylcholinesterase activity were measured in brain homogenate. alpha-Tocopherol as well astocotrienol treated groups showed significantly less cognitive impairment in both the behavioral paradigms but the effect was more potent withtocotrienol. Both isoforms of vitamin E effectively attenuated the reduction in glutathione and catalase and reduced the malonaldehyde, nitrite as well as cholinesterase activity in the brains of ICV STZ rats in a dose dependent manner. The study demonstrates the effectiveness of vitamin E isoforms, of which tocotrienol being more potent in preventing the cognitive deficits caused by ICV STZ in rats and suggests its potential in the treatment of neurodegenerative diseases such as Alzheimer’s disease.
Purpose: To compare the antifibrotic effect of vitamin E isoforms α-,γ-, and δ-tocotrienol on human Tenon’s fibroblasts (hTf) to the antimetabolite mitomycin C.
Methods: Antifbrotic effects of α- (40,60,80,100 and 120µM), γ- (10,20,330 and 40 µM) and δ–tocotrienol (10,20,30 and 40 µM) on hTf cultures were evaluated by performing proliferation, migration and collagen synthesis assays. Whereas for vitamin E the exposure time was set to 7 days to mimic subconjunctival application, cultures were exposed only 5 min to mitomycin C 100µg/ml to mimic intraoperative administration. Cell morphology (phase contrast microscopy) as an assessment for cytotoxicity and cell density by measuring DNA content in a fluorometric assay to determine proliferation inhibition was performed on day 0,4, and 7. Migration ability and collagen synthesis of fibroblasts were measured.
Results: All tested tocotrienol isoforms were able to significantly inhibit hTf proliferation in a dose dependent manner (maximal inhibitory effect without relevant morphological changes at day 4 for α-tocotrienol 80µm with 36.7% and at day 7 for α-tocotrienol 80µM with 42.6% compared to control). Degenerative cell changes were observed in cultures with concentrations above 80µM for α- and above 30µM for γ- and δ-rocotrienol. The highest collagen synthesis inhibition has been found with 80µM α-tocotrienol (62.4%) and no significant inhibition for mitomycin C (2.5%). Migration ability was significantly reduced in cultures exposed to 80µM α- and 30µM γ-tocotrienol (inhibition of 82.2% and 79.5%, respectively, compared to control) and also after mitomycin C treatment (60.0%). Complete growth inhibition without significant degenerative cell changes could only be achieved with mitomycin C.
Conclusion: In vitro, all tested tocotrienol isoforms were able to inhibit proliferation, migration and collagen synthesis of human Tenon’s fibroblasts and therefore may have the potential as an anti-scarring agent in filtrating glaucoma surgery.
A novel mechanism of natural vitamin E tocotrienol activity: Involvement of ERbeta signal transduction
Comitato R, Nesaretnam K, Leoni G, Ambra R, Canali R, Bolli A, Marino M, Virgili F.
Am J Physiol Endocrinol Metab. 2009 Aug;297(2):E427-37.
Vitamin E is a generic term used to indicate all tocopherol (TOC) and tocotrienol (TT) derivates. In the last few years, several papers have shown that a TT-rich fraction (TTRF) extracted from palm oil inhibits proliferation and induces apoptosis in a large number of cancer cells. However, the molecular mechanism(s) involved in TT action is still unclear. In the present study, we proposed for the first time a novel mechanism for TT activity that involves estrogen receptor (ER) signaling. In silico simulations and in vitro binding analyses indicated a high affinity of TTs for ERbeta but not for ERalpha. In addition, in ERbeta-containing MDA-MB-231 breast cancer cells, we demonstrated that TTs increase the ERbeta translocation into the nucleus, which in turn activates estrogen-responsive genes (MIC-1, EGR-1 and cathepsin D), as demonstrated by cell preincubation with the ER inhibitor ICI-182,780. Finally, we observed that TT treatment is associated with alteration of cell morphology, DNA fragmentation, and caspase-3 activation. Altogether, these experiments elucidated the molecular mechanism underling gamma- and delta-TT effects.
A rice bran oil diet improves lipid abnormalities and suppress hyperinsulinemic responses in rats with streptozotocin/nicotinamide-induced type 2 diabetes
Chou TW, Ma CY, Cheng HH, Chen YY, Lai MH.
J Clin Biochem Nutr. 2009 Jul;45(1):29-36. Epub 2009 Jun 30.
The aim of this study was to determine the effects of rice bran oil (RBO) on lipid metabolism and insulin resistance in rats with streptozotocin/nicotinamide-induced type 2 diabetes mellitus (T2DM). Rats were divided into two groups: the control group (15% soybean oil, contains 0 g gamma-oryzanol and 0 g gamma-tocotrienol/150 g oil for 5 weeks) and the RBO group (15% RBO, contains 5.25 g gamma-oryzanol and 0.9 g gamma-tocotrienol/150 g oil for 5 weeks). Compared with the control group, the RBO group had a lower plasma nonesterified fatty acid concentration, ratio of total to high-density-lipoprotein cholesterol, hepatic cholesterol concentration, and area under the curve for insulin. The RBO group had a higher high-density-lipoprotein cholesterol concentration and greater excretion of fecal neutral sterols and bile acid than did the control group. RBO may improve lipid abnormalities, reduce the atherogenic index, and suppress the hyperinsulinemic response in rats with streptozotocin/nicotinamide-induced T2DM. In addition, RBO can lead to increased fecal neutral sterol and bile acid excretion.
Gamma-tocotrienol, a tocol antioxidant as a potent radioprotector
Ghosh SP, Kulkarni S, Hieber K, Toles R, Romanyukha L, Kao TC, Hauer-Jensen M, Kumar KS.
Int J Radiat Biol. 2009 Jul;85(7):598-606.
Purpose: To assess the radioprotective potential of gamma-tocotrienol.
Materials And Methods: To optimise its dose and time regimen, gamma-tocotrienol (GT3) was injected subcutaneously (SC) at different doses into male CD2F1 mice [LD(50/30) (lethal radiation dose that results in the mortality of 50% mice in 30 days) radiation dose of 8.6 Gy with vehicle]. The mice were given 10.5, 11 and 11.5 Gy cobalt-60 radiation, and 30-day survival-protection was determined. Time optimisation was done by SC administration of GT3 at different intervals before irradiation. Dose reduction factor (DRF) was determined by probit analysis using mortality as the end point at six radiation doses. Protection from radiation induced pancytopenia was determined by enumerating peripheral blood cells from mice given GT3 and irradiated at 7 Gy.
Results: At an optimal dose of 200 mg/kg given SC 24 h before irradiation, GT3 had a DRF of 1.29. GT3 accelerated the recovery of total white blood cells, neutrophils, monocytes, platelets, and reticulocytes in irradiated mice, compared to vehicle-injected, irradiated controls.
Conclusion: GT3 is a radioprotectant having a higher DRF than any other tocols. The protection it provides close to the gastro-intestinal range indicate that GT3 can be considered as an ideal radioprotectant meriting further drug development stages for the ultimate use in humans.
Combined treatment of gamma-tocotrienol with statins induce mammary tumor cell cycle arrest in G1
Wali VB, Bachawal SV, Sylvester PW.
Exp Biol Med (Maywood). 2009 Jun;234(6):639-50. Epub 2009 Apr 9.
Statins and gamma-tocotrienol (a rare isoform of vitamin E) both inhibit 3-hydroxy-3-methylglutaryl-coenzyme A (HMGCoA) reductase activity and display anticancer activity. However, clinical application of statins has been limited by high dose toxicity. Previous studies showed that combinedstatin and gamma-tocotrienol treatment synergistically inhibits growth of highly malignant +SA mammary epithelial cells in culture. To investigate the mechanism mediating this growth inhibition, studies were conducted to determine the effect of combination low dose gamma-tocotrienol and statintreatment on +SA mammary tumor cell cycle progression. Treatment with 0.25 microM simvastatin, lovastatin, mevastatin, 10 microM pravastatin or 2.0 microM gamma-tocotrienol alone had no effect, while combined treatment of individual statins with gamma-tocotrienol significantly inhibited +SAcell proliferation during the 4-day culture period. Flow cytometric analysis demonstrated that combined treatment induced cell cycle arrest in G1. Additional studies showed that treatment with 0.25 microM simvastatin or 2 microM gamma-tocotrienol alone had no effect on the relative intracellular levels of cyclin D1, CDK2, CDK4 and CDK6, but combined treatment caused a large reduction in cyclin D1 and CDK2 levels. Combined treatments also caused a relatively large increase in p27, but had no effect on p21 and p15 levels, and resulted in a large reduction in retinoblastoma (Rb) protein phosphorylation at ser780 and ser807/811. Similar effects were observed following combined treatment of gamma-tocotrienol with low doses of lovastatin, mevastatin and pravastatin. These findings demonstrate that combination low dose statin and gamma-tocotrienol treatment inducedmammary tumor cell cycle arrest at G1, resulting from an increase in p27 expression, and a corresponding decrease in cyclin D1, CDK2, and hypophosphorylation of Rb protein. These findings suggest that combined treatment of statins with gamma-tocotrienol may provide significant health benefits in the treatment of breast cancer in women, while avoiding myotoxicity associated with high dose statin monotherapy.
Is vitamin E toxic to neuron cells?
Then SM, Mazlan M, Mat Top G, Wan Ngah WZ.
Cell Mol Neurobiol. 2009 Jun;29(4):485-96. Epub 2009 Jan 27.
Besides acting as potent free radical scavengers, tocopherols and tocotrienols have been known to have non-antioxidant properties such as the involvement of alpha-tocopherol (alphaT) in PKC pathway and the anti-cancer properties of gamma-tocotrienol (gammaT3). This study aims to elucidate whether protective effects shown by alphaT and gammaT3 in H(2)O(2)-induced neuron cultures have anti-apoptotic or pro-apoptotic tendency toward the initiation of neuronal apoptosis. H(2)O(2) is used to induce apoptosis in primary cerebellar neuron cultures which is attenuated by pretreatment of alphaT or gammaT3 at concentrations < or =10 microM. Similar to our previous work, gammaT3 was found to be neurotoxic at concentrations > or =100 microM, whereas alphaT showed no neurotoxicity. Cellular uptake of gammaT3 was higher than that of alphaT. Treating cells simultaneously with either gammaT3 or alphaT and with then H(2)O(2) led to higher expression of Bax and Bcl-2 than in neurons exposed to H(2)O(2) alone. Analysis of Bcl-2/Bax ratio as ‘survival index’ showed that both pretreatment of gammaT3 and alphaT followed by H(2)O(2) increase the ‘survival index’ of Bcl-2/Bax ratio compared to H(2)O(2)-treated cells, while treatment of gammaT3 alone decrease the ratio compared to unchanged Bcl2/Bax ratio of similar treatment with alphaT alone. Similar treatment of gammaT3 decreased p53 expression and activates p38 MAPK phosphorylation, whereas alphaT did not alter its expression compared to H(2)O(2)-treated cells. Treating neurons with only gammaT3 or alphaT increased the expression of Bax, Bcl-2, p53, and p38 MAPK compared to control with gammaT3 exerting stronger expression for proteins involved than alphaT. In conclusion, low doses of gammaT3 and alphaT confer neuroprotection to H(2)O(2)-treated neurons via their antioxidant mechanism but gammaT3 has stronger pro-apoptosis tendency than alphaT by activating molecules involved in the neuronal apoptotic pathway in the absence of H(2)O(2).
As rice bran tocotrienol (T3) has been known to have a wide range of physiological functions (e.g., antiangiogenesis), we aimed at developing a T3-rich rice variety for nutraceutical purposes. T3 content in more than 250 kinds of rice bran samples were investigated, and Milyang23 was found as the best variety rich in T3. The variety was therefore chosen for cross-fertilization with Koshihikari. Among obtained F(2) progenies, some of them became improved in T3 content (up to 2-fold of reference Koshihikari). QTL analysis of the F(2) progenies revealed five putative loci corresponding to T3 biosynthesis, in which the main loci were located near a marker RM3827 on chromosome 6. The results show that cross-breeding is effective in improving rice bran T3 and provides more genetic understanding on T3 biosynthesis in rice plants
The subtropical plant species Cyphostemma digitatum, Vitaceae, is used in central Yemen in traditional medicine, as a culinary herb, and as a source of food flavoring. The contents of vitamin C, vitamin E, and carotenoids and changes caused by common processing were investigated. Carotenoids were determined by reversed phase C30-high-performance liquid chromatography (HPLC) with diode array detection at 470 nm, while tocopherols and tocotrienols were analyzed by using normal phase HPLC with fluorescence detection (excitation, 292 nm; emission, 330 nm). Ascorbic acid was determined spectrophotometrically after reaction with DNP by measuring the absorbance at 520 nm. For the raw material and for the processed commercial food product, both in dried form, reasonable quantities of carotenoids were found in the raw material as follows: lutein, 18.89 +/- 0.73 mg/100 g; zeaxanthin, 9.46 +/- 0.30 mg/100 g; canthaxanthin, 0.21 +/- 0.01 mg/100 g; beta-cryptoxanthin, 0.67 +/- 0.03 mg/100 g; and beta-carotene, 14.60 +/- 0.46 mg/100 g. Household processing reduced the carotenoid contents dramatically; only beta-carotene sustained the processing. Likewise, vitamin C, 49.50 +/- 0.01 mg/100 g in the raw material and 20.30 +/- 0.02 mg/100 g in the processed material, was affected negatively by processing; only 41% was retained after processing. In contrast, the outstanding high content of vitamin E, 82.74 +/- 0.63 mg/100 g in the raw material, was increased by processing to 101.20 +/- 1.38 mg/100 g; it was found in different forms, some of which were rare in other sources.