Protective effect of dietary tocotrienols against infection and inflammation-induced hyperlipidemia: An in vivo and in silico study

Salman Khan M, Akhtar S, Al-Sagair OA, Arif JM.

Phytother Res. 2011 Nov;25(11):1586-95. Epub 2011 Mar 11.

Currently used hypolipidemic drugs, Fluvastatin and Atorvastatin, act via inhibiting the rate-limiting enzyme 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase of the mevalonate pathway. The associated severe side-effects of these statins led us to explore the therapeutic potentials of naturally occurring Tocomin (mixture of dietary α-, β-, γ- and δ-tocotrienols). Tocomin (10 mg) was orally administered daily for 10 days before and 12 h after bacterial lipopolysaccharide (200 μg) or 24 h after zymosan (20 mg) or turpentine (0.5 mL) to Syrian hamsters. The data showed that Tocomin significantly reduced the levels of plasma and lipoprotein lipids, cholesterol, apoB, small dense (sd)-LDL as well as LDL in the hyperlipidemia-induced hamsters. Further, the mechanism of action of α-, β-, γ- and δ-tocotrienols was validated by docking studies with HMG-CoA reductase enzyme using the Molegro Virtual Docker. The inhibition of HMG-CoA reductase predicted in terms of MolDockScore and interaction energy suggest the comparative potential in the descending order: Atorvastatin > Fluvastatin ~ δ > γ > β > α. The results favor the daily intake of naturally occurring tocotrienols as dietary supplement in the prevention and treatment of infection/inflammation induced dyslipidemia compared with the hypolipidemic drugs.

Assessment of the protective effects of oral tocotrienols in arginine chronic-like pancreatitis

González AM, Garcia T, Samper E, Rickmann M, Vaquero EC, Molero X.

Am J Physiol Gastrointest Liver Physiol. 2011 Nov;301(5):G846-55. Epub 2011 Aug 18.

Tocotrienols exhibit anti-inflammatory properties over macrophages and promote cytotoxicity in activated pancreatic stellate cells, suggesting that they may limit chronic pancreatitis progression. We aimed to quantitate the effect of oral tocotrienols on a rat model of chronic pancreatic injury. Chronic-like pancreatitis was induced by repeated arginine pancreatitis. Palm oil tocotrienol-rich fraction (TRF) was given by gavage before and after pancreatitis inductions. Amylase and hydroxyproline were determined in pancreatic homogenates; collagen, fibronectin, α-smooth muscle actin (SMA), glial fibrillary acidic protein (GFAP), and phosphorylated Smad3 were assessed by Western blotting. Transforming growth factor (TGF)-β1 was measured in plasma. Morphological assessment included light microscopy, fibrosis area fraction, and collagen network fractal analysis. Arginine pancreatitis induced pancreatic atrophy and increased hydroxyproline that ameliorated after TRF. Arginine increased TGF-β1 (185 ± 40 vs. 15 ± 2 ng/ml; P <0.01) that was blunted by TRF (53 ± 19; P < 0.01). TRF reduced protease and Smad3 activation, collagen, and fibronectin. α-SMA increased and GFAP diminished in arginine pancreatitis, consistent with long-term stellate cell activation, and TRF reverted these changes to basal. Arginine pancreatitis increased fibrosis area fraction (4.5 ± 0.3% vs. 0.2 ± 0.2%), collagen network complexity (fractal dimension 1.52 ± 0.03 vs. 1.42 ± 0.01; P < 0.001), and inhomogeneity (lacunarity 0.63 ± 0.03 vs. 0.40 ± 0.02; P < 0.001), which were all reduced by TRF (1.3 ± 0.4%, 1.43 ± 0.02%, and 0.51 ± 0.03%, respectively; P < 0.01). Best correlation coefficients were obtained when comparing fibrosis area fraction with lacunarity (r = 0.88) and both parameters with pancreatic weight (r = -0.91 and -0.79, respectively). TRF administered only before pancreatitis best, but not fully, recapitulated the beneficial effects of TRF. Tocotrienols improve quantitative measures of chronic pancreatic damage. They may be of benefit in human chronic pancreatitis.

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Comparison of antioxidative and antifibrotic effects of α-tocopherol with those of tocotrienol-rich fraction in a rat model of chronic pancreatitis

Jiang F, Liao Z, Hu LH, Du YQ, Man XH, Gu JJ, Gao J, Gong YF, Li ZS.

Pancreas. 2011 Oct;40(7):1091-6.

Objectives: The α-tocopherol and tocotrienol-rich fraction (TRF) are considered effective antioxidants. This study aimed to compare the antioxidative and antifibrotic effects of α-tocopherol and TFR in dibutylin dichloride (DBTC)-induced chronic pancreatitis (CP) rats.

Methods: Oral administration of α-tocopherol and TFR (both 800 mg/kg per day) started the next day after DBTC (8 mg/kg) infusion into the tail vein for 4 weeks. Histological examination, Sirius red staining, and measurement of the contents of hydroxyproline and malondialdehyde of the pancreas were performed to evaluate pancreatic damage and fibrosis. Immunohistochemical analysis of α-smooth muscle actin and real-time reverse transcription polymerase chain reaction for transforming growth factor-β1 (TGF-β1) and collagen-α1(I) were performed to evaluate the activation of pancreatic stellate cells and the mRNA levels of fibrosis-related genes, respectively.

Results: Both α-tocopherol and TRF reduced oxidative stress, ameliorated inflammation and fibrosis, and down-regulated the mRNA expression of TGF-β1 and collagen-α1(I) in DBTC-induced CP. The TRF was superior to α-tocopherol in alleviating inflammation and fibrosis and down-regulating TGF-β1 mRNA expression.

Conclusion: Oral administration of α-tocopherol and TRF improves pancreatic inflammation and fibrosis in DBTC-induced CP rats, with TRF being more effective than α-tocopherol. Therefore, TRF may be a novel option for alleviating inflammation and, particularly, the fibrotic process in CP.

The anti-inflammatory role of vitamin E in prevention of osteoporosis

Nazrun AS, Norazlina M, Norliza M, Nirwana SI.

Adv Pharmacol Sci. 2012;2012:142702. Epub 2011 Nov 17.

There is growing evidence that inflammation may be one of the causal factors of osteoporosis. Several cytokines such as IL-1, IL-6, RANKL, OPG, and M-CSF were implicated in the pathogenesis of osteoporosis. These cytokines are important determinants of osteoclast differentiation and its bone resorptive activity. Anticytokine therapy using cytokine antagonists such as IL-receptor antagonist and TNF-binding protein was able to suppress the activity of the respective cytokines and prevent bone loss. Several animal studies have shown that vitamin E in the forms of palm-derived tocotrienol and α-tocopherol may prevent osteoporosis in rat models by suppressing IL-1 and IL-6. Free radicals are known to activate transcription factor NFκB which leads to the production of bone resorbing cytokines. Vitamin E, a potent antioxidant, may be able to neutralise free radicals before they could activate NFκB, therefore suppressing cytokine production and osteoporosis. Vitamin E has also been shown to inhibit COX-2, the enzyme involved in inflammatory reactions. Of the two types of vitamin E studied, tocotrienol seemed to be better than tocopherol in terms of its ability to suppress bone-resorbing cytokines.

Suppression of nitric oxide induction and pro-inflammatory cytokines by novel proteasome inhibitors in various experimental models

Qureshi AA, Tan X, Reis JC, Badr MZ, Papasian CJ, Morrison DC, Qureshi N.

Lipids Health Dis. 2011 Oct 12;10:177.

Background: Inflammation has been implicated in a variety of diseases associated with ageing, including cancer, cardiovascular, and neurologic diseases. We have recently established that the proteasome is a pivotal regulator of inflammation, which modulates the induction of inflammatory mediators such as TNF-α, IL-1, IL-6, and nitric oxide (NO) in response to a variety of stimuli. The present study was undertaken to identify non-toxic proteasome inhibitors with the expectation that these compounds could potentially suppress the production of inflammatory mediators in ageing humans, thereby decreasing the risk of developing ageing related diseases. We evaluated the capacity of various proteasome inhibitors to suppress TNF-α, NO and gene suppression of TNF-α, and iNOS mRNA, by LPS-stimulated macrophages from several sources. Further, we evaluated the mechanisms by which these agents suppress secretion of TNF-α, and NO production. Over the course of these studies, we measured the effects of various proteasome inhibitors on the RAW 264.7 cells, and peritoneal macrophages from four different strains of mice (C57BL/6, BALB/c, proteasome double subunits knockout LMP7/MECL-1-/-, and peroxisome proliferator-activated receptor-α,-/- (PPAR-α,-/-) knockout mice. We also directly measured the effect of these proteasome inhibitors on proteolytic activity of 20S rabbit muscle proteasomes.

Results: There was significant reduction of chymotrypsin-like activity of the 20S rabbit muscle proteasomes with dexamethasone (31%), mevinolin (19%), δ-tocotrienol (28%), riboflavin (34%), and quercetin (45%; P < 0.05). Moreover, quercetin, riboflavin, and δ-tocotrienol also inhibited chymotrypsin-like, trypsin-like and post-glutamase activities in RAW 264.7 whole cells. These compounds also inhibited LPS-stimulated NO production and TNF-α, secretion, blocked the degradation of P-IκB protein, and decreased activation of NF-κB, in RAW 264.7 cells. All proteasome inhibitors tested also significantly inhibited NO production (30% to 60% reduction) by LPS-induced thioglycolate-elicited peritoneal macrophages derived from all four strains of mice. All five compounds also suppressed LPS-induced TNF-α, secretion by macrophages from C57BL/6 and BALB/c mice. TNF-α, secretion, however, was not suppressed by any of the three proteasome inhibitors tested (δ-tocotrienol, riboflavin, and quercetin) with LPS-induced macrophages from LMP7/MECL-1-/- and PPAR-α,-/- knockout mice. Results of gene expression studies for TNF-α, and iNOS were generally consistent with results obtained for TNF-α, protein and NO production observed with four strains of mice.

Conclusions: Results of the current study demonstrate that δ-tocotrienol, riboflavin, and quercetin inhibit NO production by LPS-stimulated macrophages of all four strains of mice, and TNF-α, secretion only by LPS-stimulated macrophages of C57BL/6 and BALB/c mice. The mechanism for this inhibition appears to be decreased proteolytic degradation of P-IκB protein by the inhibited proteasome, resulting in decreased translocation of activated NF-κB to the nucleus, and depressed transcription of gene expression of TNF-α, and iNOS. Further, these naturally-occurring proteasome inhibitors tested appear to be relatively potent inhibitors of multiple proteasome subunits in inflammatory proteasomes. Consequently, these agents could potentially suppress the production of inflammatory mediators in ageing humans, thereby decreasing the risk of developing a variety of ageing related diseases.

An in vivo and in silico approach to elucidate the tocotrienol-mediated fortification against infection and inflammation induced alterations in antioxidant defense system

Khan MS, Khan MK, Siddiqui MH, Arif JM.

Eur Rev Med Pharmacol Sci. 2011 Aug;15(8):916-30.

Background: Tocotrienol (Tocomin) are naturally occurring analogues of vitamin E family and has been reported to possess a potent free radical scavenging activity. In the present study we have initially investigated protective role of tocotrienol against infection and inflammation induced alterations in tissues antioxidant defense system, as well as speculated, via in silico docking studies, that tocotrienol can act by directly binding to antioxidant enzymes.

Materials And Methods: Syrian hamsters were injected with bacterial lipopolysaccharide (LPS, 200 microg), zymosan (20 mg), or turpentine (0.5 ml) to mimic acute infection, acute systemic inflammation, and acute localized inflammation, respectively, which are responsible for the generation of plenty of free radicals that causes oxidative stress. Tocomin (10 mg) was administered daily for 10 days before and 12 h after lipopolysaccharides (LPS) or 24 h after turpentine or zymosan injection. Molecular docking studies were performed using Autodock 4.0.

Results: Our results show a significant decrease in the activities of antiperoxidative enzymes, glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD), glutathione-s-transferase (GST), as well as reduced glutathione (GSH), in liver and kidney of LPS, turpentine or zymosan stressed hamsters. Feeding of 10 mg Tocomin to stressed hamsters was quite effective in reversing/normalizing the altered levels of enzymatic and nonenzymatic antioxidants in liver and kidney. In order to explore the interaction between tocotrienol and antioxidant enzymes a molecular docking study was performed. The results showed good interaction in term of binding energy and inhibition constant in the following order GR > CAT > SOD > GST > GPx.

Conclusion: Our in vivo and in silico results for the first time indicate that tocotrienol significantly alleviate the condition of oxidative stress not only by its potent free radical scavenging properties but also may be by interacting directly and strongly with antioxidant enzymes as proved by molecular docking simulations.

Role of immunoregulatory transcription factors in differential immunomodulatory effects of tocotrienols

Wilankar C, Sharma D, Checker R, Khan NM, Patwardhan R, Patil A, Sandur SK, Devasagayam TP.

Free Radic Biol Med. 2011 Jul 1;51(1):129-43. Epub 2011 Apr 8.

Tocotrienols have been shown to possess antioxidant, antitumor, cardioprotective, and antiproliferative effects. This report describes novel immunomodulatory effects of tocotrienols in murine lymphocytes. γ-Tocotrienol (GT) was more effective in suppressing concanavalin A (Con A)-induced T cell proliferation and cytokine production compared to α-tocotrienol (AT) when present continuously in the culture. GT inhibited T cell activation markers and costimulatory molecule. GT modulated intracellular glutathione in lymphocytes, and the suppressive effects of GT could not be abrogated by thiol or nonthiol antioxidants, indicating a poor link between anti-inflammatory properties of tocotrienols and cellular redox status. It was also observed that GT suppressed Con A-induced activation of NF-κB, AP-1, and NF-κB-dependent gene expression. Cellular uptake studies with tocotrienols showed higher accumulation of GT compared to AT. Similar immunosuppressive effects of GT were also observed when administered to mice. In contrast, transient exposure of lymphocytes to GT (4 h) resulted in higher survival and proliferation of lymphocytes in vitro and in vivo in syngeneic and allogeneic hosts. This was attributed to the ability of GT to induce NF-κB, AP-1, and mTOR activation in lymphocytes upon transient exposure. Our results demonstrated that antioxidants such as tocotrienols may exhibit pleiotropic effects by activating multiple mechanisms in cells.

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.

δ-Tocotrienol and quercetin reduce serum levels of nitric oxide and lipid parameters in female chickens

Qureshi AA, Reis JC, Qureshi N, Papasian CJ, Morrison DC, Schaefer DM.

Lipids Health Dis. 2011 Feb 28;10:39.

Background: Chronic, low-grade inflammation provides a link between normal ageing and the pathogenesis of age-related diseases. A series of in vitro tests confirmed the strong anti-inflammatory activities of known inhibitors of NF-κB activation (δ-tocotrienol, quercetin, riboflavin, (-) Corey lactone, amiloride, and dexamethasone). δ-Tocotrienol also suppresses β-hydroxy-β-methylglutaryl coenzyme A (HMG-CoA) reductase activity (the rate-limiting step in de novo cholesterol synthesis), and concomitantly lowers serum total and LDL cholesterol levels. We evaluated these compounds in an avian model anticipating that a dietary additive combining δ-tocotrienol with quercetin, riboflavin, (-) Corey lactone, amiloride, or dexamethasone would yield greater reductions in serum levels of total cholesterol, LDL-cholesterol and inflammatory markers (tumor necrosis factor-α [TNF-α], and nitric oxide [NO]), than that attained with the individual compounds.

Results: The present results showed that supplementation of control diets with all compounds tested except riboflavin, (-) Corey lactone, and dexamethasone produced small but significant reductions in body weight gains as compared to control. (-) Corey lactone and riboflavin did not significantly impact body weight gains. Dexamethasone significantly and markedly reduced weight gain (>75%) compared to control. The serum levels of TNF-α and NO were decreased 61% – 84% (P < 0.001), and 14% – 67%, respectively, in chickens fed diets supplemented with δ-tocotrienol, quercetin, riboflavin, (-) Corey lactone, amiloride, or dexamethasone as compared to controls. Significant decreases in the levels of serum total and LDL-cholesterol were attained with δ-tocotrienol, quercetin, riboflavin and (-) Corey lactone (13% – 57%; P < 0.05), whereas, these levels were 2-fold higher in dexamethasone treated chickens as compared to controls. Parallel responses on hepatic lipid infiltration were confirmed by histological analyses. Treatments combining δ-tocotrienol with the other compounds yielded values that were lower than individual values attained with either δ-tocotrienol or the second compound. Exceptions were the significantly lower total and LDL cholesterol and triglyceride values attained with the δ-tocotrienol/(-) Corey lactone treatment and the significantly lower triglyceride value attained with the δ-tocotrienol/riboflavin treatment. δ-Tocotrienol attenuated the lipid-elevating impact of dexamethasone and potentiated the triglyceride lowering impact of riboflavin. Microarray analyses of liver samples identified 62 genes whose expressions were either up-regulated or down-regulated by all compounds suggesting common impact on serum TNF-α and NO levels. The microarray analyses further identified 41 genes whose expression was differentially impacted by the compounds shown to lower serum lipid levels and dexamethasone, associated with markedly elevated serum lipids.

Conclusion: This is the first report describing the anti-inflammatory effects of δ-tocotrienol, quercetin, riboflavin, (-) Corey lactone, amiloride, and dexamethasone on serum TNF-δ and NO levels. Serum TNF-δ levels were decreased by >60% by each of the experimental compounds. Additionally, all the treatments except with dexamethasone, resulted in lower serum total cholesterol, LDL-cholesterol and triglyceride levels. The impact of above mentioned compounds on the factors evaluated herein was increased when combined with δ-tocotrienol.

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