This review emphasizes the effects of tocotrienols on the risk factors for atherosclerosis, plaque instability and thrombogenesis, and compares these effects with tocopherol. Tocotrienols reduce serum lipids and raise serum HDL-C. Alpha-tocopherol, on the other hand, has no effect on serum lipids. Tocotrienols have greater antioxidant activity than tocopherols. Both reduce the serum levels of C-reactive protein (CRP) and advanced glycation end products, and expression of cell adhesion molecules. The CRP-lowering effects of tocotrienols are greater than tocopherol. Tocotrienols reduce inflammatory mediators, δ-tocotrienol being more potent, followed by γ- and α-tocotrienol. Tocotrienols are antithrombotic and suppress the expression of matrix metalloproteinases. They suppress, regress and slow the progression of atherosclerosis, while tocopherol only suppresses, and has no effect on regression and slowing of progression of atherosclerosis. Tocotrienol reduces risk factors for destabilization of atherosclerotic plaques. There are no firm data to suggest that tocotrienols are effective in reducing the risk of cardiac events in established ischemic heart disease. Alpha-tocopherol is effective in primary prevention of coronary artery disease (CAD), but has no conclusive evidence that it has beneficial effects in patients with established ischemic heart disease. Tocotrienols are effective in reducing ischemia-reperfusion cardiac injury in experimental animals and has the potential to be used in patients undergoing angioplasty, stent implantation and aorto-coronary bypass surgery. In conclusion, experimental data suggest that tocotrienols have a potential for cardiovascular health, but long-term randomized clinical trials are needed to establish their efficacy in primary and secondary prevention of CAD.
Monthly Archives: July 2011
The worldwide cardiovascular disease (CVD) burden has resulted in an intense interest in pharmaceutical approaches to combat this multifactorial disease. Vitamins are high-flying among natural or endogenous compounds, considered to be beneficial to human health and have become attractive targets for research. Of all the vitamins, tocopherols and tocotrienols, parent congeners in the vitamin E family, are found to be effective in decreasing mortality due to CVD. As understanding of the antioxidant effect of this vitamin evolved, tocotrienols gained eminence in recent years and researchers begun to further study the biological effects of it. Tocotrienols have several cardioprotective effects; including antagonizing the oxidation of low density lipoproteins, anti atherosclerotic, inhibiting platelet aggregation and monocyte adhesion, preventing smooth muscle proliferation and various other cardiovascular disorders. Recent studies have also revealed the molecular targets of the tocotrienols and their roles in cancer, bone resorption, diabetes and neurological diseases at both preclinical and clinical levels. The multitargeted role of tocotrienols in most degenerative diseases proves it to be an ideal candidate as a nutraceutical/pharmaceutical agent for useful exploitation.
Inhibitory effects of palm α-, γ- and δ-tocotrienol on lipopolysaccharide-induced nitric oxide production in BV2 microglia
Tan SW, Ramasamy R, Abdullah M, Vidyadaran S
Cell Immunol. 2011;271(2):205-9. Epub 2011 Jul 23
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.
Vitamin E forms inhibit IL-13/STAT6-induced eotaxin-3 secretion by up-regulation of PAR4, an endogenous inhibitor of atypical PKC in human lung epithelial cells
Wang Y, Moreland M, Wagner JG, Ames BN, Illek B, Peden DB, Jiang Q.
J Nutr Biochem. 2011 Jul 15.
Eotaxin-3 (CCL-26), a potent chemokine for eosinophil recruitment and contributing significantly to the pathogenesis of asthma, is secreted by lung epithelial cells in response to T helper 2 cytokines including interleukin 13 (IL-13). Here we showed that vitamin E forms, but not their metabolites, differentially inhibited IL-13-stimulated generation of eotaxin-3 in human lung epithelial A549 cells. The relative inhibitory potency was γ-tocotrienol (γ-TE) (IC50 ∼15 μM)>γ-tocopherol, δ-tocopherol (IC50 ∼25-50 μM)>α-tocopherol. Consistent with suppression of eotaxin, γ-TE treatment impaired IL-13-induced phosphorylation of STAT6, the key transcription factor for activation of eotaxin expression, and consequently blocked IL-13-stimulated DNA-binding activity of STAT6. In search of the upstream target of γTE by using inhibitor and siRNA approaches, we discovered that the atypical protein kinase C (aPKC) signaling, instead of classical PKC, p38 MAPK, JNK or ERK, played a critical role in IL-13-stimulated eotaxin generation and STAT6 activation. While showing no obvious effect on aPKC expression or phosphorylation, γ-TE treatment resulted in increased expression of prostate-apoptosis-response 4 (PAR4), an endogenous negative regulator of aPKCs. Importantly, γ-TE treatment led to enhanced formation of aPKC/PAR4 complex that is known to reduce aPKC activity via protein-protein crosstalk. Our study demonstrated that γ-TE inhibited IL-13/STAT6-activated eotaxin secretion via up-regulation of PAR4 expression and enhancement of aPKC-PAR4 complex formation. These results support the notion that specific vitamin E forms may be useful anti-asthmatic agents.
Tocotrienols: Inflammation and cancer
Nesaretnam K, Meganathan P.
Ann N Y Acad Sci. 2011 Jul;1229:18-22.
Inflammation is an organism’s response to environmental assaults. It can be classified as acute inflammation that leads to therapeutic recovery or chronic inflammation, which may lead to the development of cancer and other ailments. Genetic changes that occur within cancer cells themselves are responsible for many aspects of cancer development but are dependent on ancillary processes for tumor promotion and progression. Inflammation has long been associated with the development of cancer. The distinct characteristics of cancer cells to proliferate, metastasize, evade apoptotic signals, and develop chemoresistance have been linked to the inflammatory response. Due to the involvement of multiple genes and various pathways, current drugs that target single genes have not been effective in providing a therapeutic cure. On the other hand, natural products target multiple genes and therefore have better success compared to drugs. Tocotrienols, the potent isoforms of vitamin E, are such a natural product. This review will discuss the relationship between cancer and inflammation with particular focus on the roles played by NF-κB, STAT3, and COX-2.
Studies show how tocotrienols reduce stroke damage
Reports published online on June 15, 2011 in the Journal of Cerebral Blood Flow & Metabolism and on June 30, 2011 in the journal Stroke reveal the findings of Ohio State University professor Chandan K. Sen and his associates of protective effects for tocotrienols against the damage incurred by stroke. Alpha, beta, gamma and delta tocotrienols are four of the eight forms in which vitamin E occurs and, while not abundant in Western diets, are available in supplemental form.
‘Gifted’ Natural Vitamin E Tocotrienol Protects Brain Against Stroke in Three Ways
A natural form of vitamin E called alpha-tocotrienol can trigger production of a protein in the brain that clears toxins from nerve cells, preventing those cells from dying after a stroke, new research shows.