Anti-inflammatory actions of the vitamin E fragment tocotrienol have not been described for microglia. Here, we screened palm alpha-, gamma- and delta-tocotrienol isoforms and Tocomin(R) 50% (contains spectrum of tocotrienols and tocopherols) for their ability to limit nitric oxide (NO) production by BV2 microglia. Microglia were treated with varying doses of tocotrienols for 24h and stimulated with 1 mug/ml lipopolysaccharide (LPS). All tocotrienol isoforms reduced NO release by LPS-stimulated microglia, with 50 muM being the most potent tocotrienol dose. Of the isoforms tested, delta-tocotrienol lowered NO levels the most, reducing NO by approximately 50% at 48 h post-LPS treatment (p<.05). None of the tocotrienol doses tested affected microglia viability.
Brain and Nerve Health
Hydrogen peroxide induces neurite degeneration: Prevention by tocotrienols
Fukui K, Takatsu H, Koike T, Urano S.
Free Radic Res. 2011 Jun;45(6):681-91.
Reactive oxygen species (ROS) may attack several types of tissues and chronic exposure to ROS may attenuate various biological functions and increase the risk of several types of serious disorders. It is known that treatments with ROS attack neurons and induce cell death. However, the mechanisms of neuronal change by ROS prior to induction of cell death are not yet understood. Here, it was found that treatment of neurons with low concentrations of hydrogen peroxide induced neurite injury, but not cell death. Unusual bands located above the original collapsin response mediator protein (CRMP)-2 protein were detected by western blotting. Treatment with tocopherol or tocotrienols significantly inhibited these changes in neuro2a cells and cerebellar granule neurons (CGCs). Furthermore, prevention by tocotrienols of hydrogen peroxide-induced neurite degeneration was stronger than that by tocopherol. These findings indicate that neurite beading is one of the early events of neuronal degeneration prior to induction of death of hydrogen peroxide-treated neurons. Treatment with tocotrienols may protect neurite function through its neuroprotective function.
Tocotrienols-induced inhibition of platelet thrombus formation and platelet aggregation in stenosed canine coronary arteries
Qureshi AA, Karpen CW, Qureshi N, Papasian CJ, Morrison DC, Folts JD.
Lipids Health Dis. 2011 Apr 14;10:58.
Background: Dietary supplementation with tocotrienols has been shown to decrease the risk of coronary artery disease. Tocotrienols are plant-derived forms of vitamin E, which have potent anti-inflammatory, antioxidant, anticancer, hypocholesterolemic, and neuroprotective properties. Our objective in this study was to determine the extent to which tocotrienols inhibit platelet aggregation and reduce coronary thrombosis, a major risk factor for stroke in humans. The present study was carried out to determine the comparative effects of α-tocopherol, α-tocotrienol, or tocotrienol rich fraction (TRF; a mixture of α-+γ-+δ-tocotrienols) on in vivo platelet thrombosis and ex vivo platelet aggregation (PA) after intravenous injection in anesthetized dogs, by using a mechanically stenosed circumflex coronary artery model (Folts’ cyclic flow model).
Results: Collagen-induced platelet aggregation (PA) in platelet rich plasma (PRP) was decreased markedly after treatment with α-tocotrienol (59%; P<0.001) and TRF (92%; P<0.001). α-Tocopherol treatment was less effective, producing only a 22% (P<0.05) decrease in PA. Adenosine diphosphate-induced (ADP) PA was also decreased after treatment with α-tocotrienol (34%; P<0.05) and TRF (42%; P<0.025). These results also indicate that intravenously administered tocotrienols were significantly better than tocopherols in inhibiting cyclic flow reductions (CFRs), a measure of the acute platelet-mediated thrombus formation. Tocotrienols (TRF) given intravenously (10 mg/kg), abolished CFRs after a mean of 68 min (range 22 -130 min), and this abolition of CFRs was sustained throughout the monitoring period (50-160 min).Next, pharmacokinetic studies were carried out and tocol levels in canine plasma and platelets were measured. As expected, α-Tocopherol treatment increased levels of total tocopherols in post- vs pre-treatment specimens (57 vs 18 μg/mL in plasma, and 42 vs 10 μg/mL in platelets). However, treatment with α-tocopherol resulted in slightly decreased levels of tocotrienols in post- vs pre-treatment samples (1.4 vs 2.9 μg/mL in plasma and 2.3 vs 2.8 μg/mL in platelets). α-Tocotrienoltreatment increased levels of both tocopherols and tocotrienols in post- vs pre-treatment samples (tocopherols, 45 vs 10 μg/mL in plasma and 28 vs 5 μg/mL in platelets; tocotrienols, 2.8 vs 0.9 μg/mL in plasma and 1.28 vs 1.02 μg/mL in platelets). Treatment with tocotrienols (TRF) also increased levels of tocopherols and tocotrienols in post- vs pre-treatment samples (tocopherols, 68 vs 20 μg/mL in plasma and 31.4 vs 7.9 μg/mL in platelets;tocotrienols, 8.6 vs 1.7 μg/mL in plasma and 3.8 vs 3.9 μg/mL in platelets).
Conclusions: The present results indicate that intravenously administered tocotrienols inhibited acute platelet-mediated thrombus formation, and collagen and ADP-induced platelet aggregation. α-Tocotrienols treatment induced increases in α-tocopherol levels of 4-fold and 6-fold in plasma and platelets, respectively. Interestingly, tocotrienols (TRF) treatment induced a less pronounced increase in the levels of tocotrienols in plasma and platelets, suggesting that intravenously administered tocotrienols may be converted to tocopherols. Tocotrienols, given intravenously, could potentially prevent pathological platelet thrombus formation and thus provide a therapeutic benefit in conditions such as stroke and myocardial infarction.
High plasma levels of vitamin E forms and reduced Alzheimer’s disease risk in advanced age
Mangialasche F, Kivipelto M, Mecocci P, Rizzuto D, Palmer K, Winblad B, Fratiglioni L.
J Alzheimers Dis. 2010;20(4):1029-37.
In this study we investigated the association between plasma levels of eight forms of vitamin E and incidence of Alzheimer’s disease (AD) among oldest-old individuals in a population-based setting. A dementia-free sample of 232 subjects aged 80+ years, derived from the Kungsholmen Project, was followed-up to 6 years to detect incident AD. Plasma levels of vitamin E (alpha-, beta-, gamma, and delta-tocopherol; alpha-, beta-, gamma-, and delta-tocotrienol) were measured at baseline. Vitamin E forms-AD association was analyzed with Cox proportional hazard model after adjustment for several potential confounders. Subjects with plasma levels of total tocopherols, total tocotrienols, or total vitamin E in the highest tertile had a reduced risk of developing AD in comparison to persons in the lowest tertile. Multi-adjusted hazard ratios (HRs) and 95% confidence interval (CI) were 0.55 (0.32-0.94) for total tocopherols, 0.46 (0.23-0.92) for total tocotrienols, and 0.55 (0.32-0.94) for total vitamin E. When considering each vitamin E form, the risk of developing AD was reduced only in association with high plasma levels of beta-tocopherol (HR: 0.62, 95% CI 0.39-0.99), whereas alpha-tocopherol, alpha- tocotrienol, and beta-tocotrienol showed only a marginally significant effect in the multiadjusted model [HR (95% CI): alpha-tocopherol: 0.72 (0.48-1.09); alpha-tocotrienol: 0.70 (0.44-1.11); beta-tocotrienol: 0.69 (0.45-1.06)]. In conclusion, high plasma levels of vitamin E are associated with a reduced risk of AD in advanced age. The neuroprotective effect of vitamin E seems to be related to the combination of different forms, rather than to alpha-tocopherol alone, whose efficacy in interventions against AD is currently debated.
Cytoprotective effects of vitamin E homologues against glutamate-induced cell death in immature primary cortical neuron cultures: Tocopherols and tocotrienols exert similar effects by antioxidant function
Saito Y, Nishio K, Akazawa YO, Yamanaka K, Miyama A, Yoshida Y, Noguchi N, Niki E.
Free Radic Biol Med. 2010 Nov 30;49(10):1542-9. Epub 2010 Aug 22.
Glutamate plays a critical role in pathological cell death within the nervous system. Vitamin E is known to protect cells from glutamate cytotoxicity, either by direct antioxidant action or by indirect nonantioxidant action. Further, α-tocotrienol (α-T3) has been reported to be more effective against glutamate-induced cytotoxicity than α-tocopherol (α-T). To shed more light on the function of vitamin E against glutamate toxicity, the protective effects of eight vitamin E homologues and related compounds, 2,2,5,7,8-pentamethyl-6-chromanol (PMC) and 2-carboxy-2,5,7,8-pentamethyl-6-chromanol (Trolox), against glutamate-induced cytotoxicity on immature primary cortical neurons were examined using different protocols. Glutamate induced the depletion of glutathione and generation of reactive oxygen species and lipid hydroperoxides, leading to cell death. α-, β-, γ-, and δ-T and -T3; PMC; and Trolox all exerted cytoprotective effects against glutamate-induced cytotoxicity, and a longer preincubation time increased both the cellular content and the cytoprotective effects of T more significantly than those of T3, the effect of preincubation being relatively small for T3 and PMC. The protective effect of Trolox was less potent than that of PMC. The cytoprotective effects of α-T and α-T3 corresponded to their intracellular content. Further, lipid peroxidation products were measured after reduction with triphenylphosphine followed by saponification with potassium hydroxide. It was found that glutamate treatment increased the formation of hydroxyeicosatetraenoic acid, hydroxyoctadecadienoic acid, and 8-F(2)-isoprostane 2α, which was suppressed by α-T. This study shows that vitamin E protects cells from glutamate-induced toxicity primarily by direct antioxidant action and that the apparent higher capacity of T3 compared to T is ascribed to the faster uptake of T3 compared to T into the cells. It is suggested that, considering the bioavailability, α-T should be more effective than α-T3 against glutamate toxicity in vivo.
Palm oil–derived natural vitamin E α-tocotrienol in brain health and disease
Chandan K. Sen, PhD, Cameron Rink, PhD, and Savita Khanna, PhD
J Am Coll Nutr. 2010 June ; 29(3 Suppl): 314S–323S.
A growing body of research supports that members of the vitamin E family are not redundant with respect to their biological function. Palm oil derived from Elaeis guineensis represents the richest source of the lesser characterized vitamin E, α-tocotrienol. One of 8 naturally occurring and chemically distinct vitamin E analogs, α-tocotrienol possesses unique biological activity that is independent of its potent antioxidant capacity. Current developments in α-tocotrienol research demonstrate neuroprotective properties for the lipid-soluble vitamin in brain tissue rich in polyunsaturated fatty acids (PUFAs). Arachidonic acid (AA), one of the most abundant PUFAs of the central nervous system, is highly susceptible to oxidative metabolism under pathologic conditions. Cleaved from the membrane phospholipid bilayer by cytosolic phospholipase A2, AA is metabolized by both enzymatic and nonenzymatic pathways. A number of neurodegenerative conditions in the human brain are associated with disturbed PUFA metabolism of AA, including acute ischemic stroke. Palm oil–derived α-tocotrienol at nanomolar concentrations has been shown to attenuate both enzymatic and nonenzymatic mediators of AA metabolism and neurodegeneration. On a concentration basis, this represents the most potent of all biological functions exhibited by any natural vitamin E molecule. Despite such therapeutic potential, the scientific literature on tocotrienols accounts for roughly 1% of the total literature on vitamin E, thus warranting further investment and investigation
Nanomolar vitamin E alpha-tocotrienol inhibits glutamate-induced activation of phospholipase A2 and causes neuroprotection
Khanna S, Parinandi NL, Kotha SR, Roy S, Rink C, Bibus D, Sen CK.
J Neurochem. 2010 Mar;112(5):1249-60. Epub 2009 Dec 17.
Our previous works have elucidated that the 12-lipoxygenase pathway is directly implicated in glutamate-induced neural cell death, and that such that toxicity is prevented by nM concentrations of the natural vitamin E alpha-tocotrienol (TCT). In the current study we tested the hypothesis that phospholipase A(2) (PLA(2)) activity is sensitive to glutamate and mobilizes arachidonic acid (AA), a substrate for 12-lipoxygenase. Furthermore, we examined whether TCT regulates glutamate-inducible PLA(2) activity in neural cells. Glutamate challenge induced the release of [(3)H]AA from HT4 neural cells. Such response was attenuated by calcium chelators (EGTA and BAPTA), cytosolic PLA(2) (cPLA(2))-specific inhibitor (AACOCF(3)) as well as TCT at 250 nM. Glutamate also caused the elevation of free polyunsaturated fatty acid (AA and docosahexaenoic acid) levels and disappearance of phospholipid-esterified AA in neural cells. Furthermore, glutamate induced a time-dependent translocation and enhanced serine phosphorylation of cPLA(2) in the cells. These effects of glutamate on fatty acid levels and on cPLA(2) were significantly attenuated by nM TCT. The observations that AACOCF(3), transient knock-down of cPLA(2) as well as TCT significantly protected against the glutamate-induced death of neural cells implicate cPLA(2) as a TCT-sensitive mediator of glutamate induced neural cell death. This work presents first evidence recognizing glutamate-induced changes in cPLA(2) as a novel mechanism responsible for neuroprotection observed in response to nanomolar concentrations of TCT.
Tocotrienol attenuates oxidative-nitrosative stress and inflammatory cascade in experimental model of diabetic neuropathy
Kuhad, A.,Chopra, K.
Pharmacol Biochem Behav, 2009. 92(2):251-9.
Diabetic neuropathic pain, an important microvascular complication in diabetes mellitus, is recognised as one of the most difficult types of pain to treat. The development of tolerance, inadequate relief and potential toxicity of classical antinociceptives warrant the investigation of the newer agents to relieve this pain. Reactive oxygen/nitrogen species, cytokines and apoptosis are implicated in the pathogenesis of diabetic neuropathy. The aim of the present study was to explore the effect of tocotrienol on thermal and mechanical hyperalgesia, allodynia, oxidative-nitrosative stress, inflammation and apoptosis in streptozotocin-induced experimental diabetes. Diabetic rats developed neuropathy which was evident from a marked hyperalgesia and allodynia associated with enhanced nitrosative stress, release of inflammatory mediators (TNF-alpha, IL-1beta, TGF-1beta) and caspase-3. Chronic treatment with tocotrienol (25, 50 and 100 mg/kg body weight; p.o.) for 4 weeks starting from the 4th week of streptozotocin injection significantly attenuated behavioral, biochemical and molecular changes associated with diabetic neuropathy. Moreover, diabetic rats treated with insulin-tocotrienol combination produced more pronounced beneficial effect as compared to their per se groups. The major finding of the study is that insulin alone corrected the hyperglycemia and partially reversed the pain response in diabetic rats. However, combination with tocotrienol not only attenuated the diabetic condition but also reversed neuropathic pain through modulation of oxidative-nitrosative stress, inflammatory cytokine release and caspase-3 in the diabetic rats and thus it may find clinical application to treat neuropathic pain in the diabetic patients.
Assessing the neuroprotective effect of antioxidative food factors by application of lipid-derived dopamine modification adducts
Liu X, Yamada N, Osawa T.
Methods Mol Biol. 2009;580:143-52.
Advances in understanding the neurodegenerative pathologies are creating new opportunities for the development of neuroprotective therapies, such as antioxidant food factors, lifestyle modification, and drugs. However, the biomarker by which to determine the effect of the agent on neurodegeneration is limited. We here address hexanoyl dopamine (HED), one of novel dopamine adducts derived from brain polyunsaturated acid, referring to its in vitro formation, potent toxicity to SH-SY5Y cells, and application to assess the neuroprotective effect of antioxidative food factors. Dopamine is a neurotransmitter and its deficiency is a characterized feature in Parkinson’s disease (PD), thereby HED represents a new addition to understanding of dopamine biology and pathophysiology of PD and a novel biomarker for the assessment of neuroprotective therapies. We have established an analytical system using for the detection of HED and its toxicity to the neuroblstoma cell line, SH-SY5Y cells. Here, we discuss the characteristics of the system and its applications to investigate the neuroprotective effect of several antioxidants that originate from food.
Suppression of neuro-inflammatory signaling cascade by tocotrienol can prevent chronic alcohol-induced cognitive dysfunction in rats
Tiwari V, Kuhad A, Chopra K.
Behav Brain Res. 2009 Nov 5;203(2):296-303.
Chronic alcohol intake is known to induce the selective neuronal damage associated with increase oxidative-nitrosative stress and activation of inflammatory cascade finally resulting in neuronal apoptosis and thus dementia. In the present study, we investigated the comparative effect of both the isoforms of vitamin E, alpha-tocopherol and tocotrienol against chronic alcohol-induced cognitive dysfunction in rats. Male Wistar rats were given ethanol (10g/kg; oral gavage) for 10 weeks, and treated with alpha-tocopherol and tocotrienol for the same duration. The learning and memory behavior was assessed using Morris water maze and elevated plus maze test. The rats were sacrificed at the end of 10th week and cytoplasmic fractions of cerebral cortex and hippocampus were prepared for the quantification of acetylcholinesterase activity, oxidative-nitrosative stress parameters, tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta). From the 6th week onwards, ethanol-treated rats showed significant increase in transfer latency in both the behavioral paradigms which was coupled with enhanced acetylcholinesterase activity, increased oxidative-nitrosative stress, TNF-alpha and IL-1beta levels in different brain regions of ethanol-treated rats. Co-administration of alpha-tocopherol as well as tocotrienol significantly and dose-dependently prevented these behavioral, biochemical and molecular changes in the brains of ethanol-treated rats. However, the effects were more pronounced with tocotrienol. The current study thus demonstrates the possible involvement of oxidative-nitrosative stress mediated activation of inflammatory cascade in chronic alcohol-induced cognitive dysfunction and also suggests the effectiveness of vitamin E isoforms, of which tocotrienol being more potent, in preventing the cognitive deficits associated with chronic alcohol consumption.