Publications

Activation of autophagy and AMPK by gamma-tocotrienol suppresses the adipogenesis in human adipose derived stem cells.

Zhao L, Ha JH, Okla M, Chung S.

SCOPE:

This study investigated the mechanistic details by which gamma-tocotrienol (γ-T3) manipulates adipocyte differentiation in human adipose derived stem cells (hASCs).

METHODS AND RESULTS:

γ-T3 specifically inhibited the early stage of adipocyte differentiation by acting on downstream of C/EBP-β but upstream of C/EBP-α in hASCs. In searching a potential mechanism, we identified that γ-T3 promoted two catabolic signaling pathways: (i) AMP kinase (AMPK), and (ii) enhanced autophagy, as assessed by autophagic flux and cytosolic autophagosome (LC3II) accumulation. In addition, chronic exposure of γ-T3 induced caspase3-mediated apoptotic cell death. The blockage of AMPK by a dominant negative mutant of AMPK was insufficient to normalize γ-T3-mediated autophagy, suggesting that enhanced autophagic activity of γ-T3 is independent of AMPK activation. Intriguingly, AMPK inhibition significantly restored PPAR-γ activation, but marginally rescued lipid-loaded adipocyte morphology due to, at least partly, a lack of lipid droplet-coating protein. These data suggest that γ-T3 activates AMPK and autophagy signaling, which synergistically contributes to the suppression of adipogenic conversion of hASCs into adipocytes.

CONCLUSION:

These results provide a novel insight into the molecular mechanism involved in anti-adipogenic action of γ-T3 in humans via AMPK and autophagy activation. Thus, γ-T3 may constitute a new dietary avenue to attenuate hyperplastic obesity in humans.

Can ω-3 fatty acids and tocotrienol-rich vitamin E reduce symptoms of neurodevelopmental disorders?

Gumpricht E, Rockway S.

The incidence of childhood neurodevelopmental disorders, which include autism, attention-deficit hyperactivity disorders, and apraxia, are increasing worldwide and have a profound effect on the behaviors, cognitive skills, mood, and self-esteem of these children. Although the etiologies of these disorders are unclear, they often accompany genetic and biochemical abnormalities resulting in cognitive and communication difficulties. Because cognitive and neural development require essential fatty acids (particularly long-chain ω-3 fatty acids often lacking in mother’s and children’s diets) during critical growth periods, the potential behavior-modifying effects of these fatty acids as “brain nutrients” has attracted considerable attention. Additionally, there is compelling evidence for increased oxidative stress, altered antioxidant defenses, and neuroinflammation in these children. The purpose of this review is to provide a scientific rationale based on cellular, experimental animal model, observational, and clinical intervention studies for incorporating the combination of ω-3 fatty acids and tocotrienol-rich vitamin E as complementary nutritional therapies in children with neurodevelopmental disorders. Should this nutritional combination correct key clinical or biochemical outcomes and/or improve behavioral patterns, it would provide a safe, complementary option for these children.

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Molecular dynamics guided design of tocoflexol: a new radioprotectant tocotrienol with enhanced bioavailability.

Compadre CM, Singh A, Thakkar S, Zheng G, Breen PJ, Ghosh S, Kiaei M, Boerma M, Varughese KI, Hauer-Jensen M.

Preclinical Research There is a pressing need to develop safe and effective radioprotector/radiomitigator agents for use in accidental or terrorist-initiated radiological emergencies. Naturally occurring vitamin E family constituents, termed tocols, that include the tocotrienols, are known to have radiation-protection properties. These agents, which work through multiple mechanisms, are promising radioprotectant agents having minimal toxicity. Although α-tocopherol (AT) is the most commonly studied form of vitamin E, the tocotrienols are more potent than AT in providing radioprotection and radiomitigation. Unfortunately, despite their very significant radioprotectant activity, tocotrienols have very short plasma half-lives and require dosing at very high levels to achieve necessary therapeutic benefits. Thus, it would be highly desirable to develop new vitamin E analogues with improved pharmacokinetic properties, specifically increased elimination half-life and increased area under the plasma level versus time curve. The short elimination half-life of the tocotrienols is related to their low affinity for the α-tocopherol transfer protein (ATTP), the protein responsible for maintaining the plasma level of the tocols. Tocotrienols have less affinity for ATTP than does AT, and thus have a longer residence time in the liver, putting them at higher risk for metabolism and biliary excretion. We hypothesized that the low-binding affinity of tocotrienols to ATTP is due to the relatively more rigid tail structure of the tocotrienols in comparison with that of the tocopherols. Therefore, compounds with a more flexible tail would have better binding to ATTP and consequently would have longer elimination half-life and, consequently, an increased exposure to drug, as measured by area under the plasma drug level versus time curve (AUC). This represents an enhanced residence of drug in the systemic circulation. Based on this hypothesis, we developed a new class of vitamin E analogues, the tocoflexols, which maintain the superior bioactivity of the tocotrienols with the potential to achieve the longer half-life and larger AUC of the tocopherols.

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Comparable down-regulation of TYR, TYRP1 and TYRP2 genes and inhibition of melanogenesis by tyrostat, tocotrienol-rich fraction and tocopherol in human skin melanocytes improves skin pigmentation.

Makpol S, Jam FA, Rahim NA, Khor SC, Ismail Z, Yusof YA, Wan Ngah WZ.

BACKGROUND AND OBJECTIVE:

Antioxidant has been recognized to inhibit UV-induced melanogenesis. This study aimed to elucidate the molecular mechanism of tyrostat, tocopherol and tocotrienol-rich fraction in inhibiting melanogenesis in human skin melanocytes.

MATERIALS AND METHODS:

Primary culture of melanocytes was exposed to repeated doses of 0.6 J/cm2 UVA for 6 days and treated with tyrostat, tocotrienol-rich fraction or tocopherol alone or in combination.

RESULTS:

UVA irradiation increased melanin content and tyrosinase activity and up-regulated TYR, TYRP1 and TYRP2 genes. Treatment with tyrostat, tocotrienol-rich fraction or tocopherol decreased melanin content and down-regulated TYR, TYRP1 and TYRP2 genes with decreased tyrosinase activity. Combined treatment exerted better effects as compared to treatment with single compound in decreasing the melanin content and down-regulating TYR, TYRP1 and TYRP2 genes. These findings indicated that tyrostat, tocotrienol-rich fraction and tocopherol inhibit melanogenesis by modulating the expression of genes involved in the regulation of melanin synthesis and inhibiting tyrosinase activity.

CONCLUSIONS:

Tyrostat, tocopherol and tocotrienol-rich fraction possessed anti-melanogenic properties and might be useful in improving skin pigmentation caused by UVA exposure.

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Inhibitory effects of palm tocotrienol-rich fraction supplementation on bilirubin-metabolizing enzymes in hyperbilirubinemic adult rats.

Kamisah Y, Lim JJ, Lim CL, Asmadi AY.

BACKGROUND:

Phenylhydrazine, a hemolytic agent, is widely used as a model of experimental hyperbilirubinemia. Palm tocotrienol-rich fraction (TRF) was shown to exert beneficial effects in hyperbilirubinemic rat neonates.

AIM:

To investigate the effects of palm TRF supplementation on hepatic bilirubin-metabolizing enzymes and ocidative stress status in rats administered phenylhydrazine.

METHODS:

Twenty-four male Wistar rats were divided into two groups; one group was intraperitoneally injected with palm TRF at the dose of 30 mg/kg/day, while another group was only given vehicle (control) (vitamin E-free palm oil) for 14 days. Twenty-four hours after the last dose, each group was further subdivided into another two groups. One group was administered phenylhydrazine (100 mg/kg, intraperitoneally) and another group was administered normal saline. Twenty-four hours later, blood and liver were collected for biochemical parameter measurements.

RESULTS:

Phenylhydrazine increased plasma total bilirubin level and oxidative stress in the erythrocytes as well as in the liver, which were reduced by the pretreatment of palm TRF. Palm TRF also prevented the increases in hepatic heme oxygenase, biliverdin reductase and UDP-glucuronyltransferase activities induced by phenylhydrazine.

CONCLUSION:

Palm tocotrienol-rich fraction was able to afford protection against phenylhydrazine-induced hyperbilirubinemia, possibly by reducing oxidative stress and inhibiting bilirubin-metabolizing enzymes in the liver.

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Radioprotective efficacy of delta-tocotrienol, a vitamin E isoform, is mediated through granulocyte colony-stimulating factor.

Singh VK, Wise SY, Scott JR, Romaine PL, Newman VL, Fatanmi OO.

AIMS:

The objectives of this study were to determine the cytokine induction by delta tocotrienol (DT3, a promising radiation countermeasure) and to investigate the role of granulocyte colony-stimulating factor (G-CSF) in its radioprotective efficacy against ionizing radiation in mice.

MAIN METHODS:

Multiplex Luminex was used to analyze cytokines induced by DT3 and other tocols (gamma-tocotrienol and tocopherol succinate) CD2F1 mice. Mice were injected with an optimal dose of DT3 and a G-CSF antibody, and their 30-day survival against cobalt-60 gamma-irradiation was monitored. The neutralization of G-CSF by the administration of a G-CSF-specific antibody in DT3-injected mice was investigated by multiplex Luminex.

KEY FINDINGS:

Our data demonstrate that DT3 induced high levels of various cytokines comparable to other tocols being developed as radiation countermeasures. DT3 significantly protected mice against ionizing radiation, and the administration of a G-CSF neutralizing antibody to DT3-treated animals resulted in the complete abrogation of DT3’s radioprotective efficacy and neutralization of G-CSF in peripheral blood.

SIGNIFICANCE:

Our study findings suggest that G-CSF induced by DT3 mediates its radioprotective efficacy against ionizing radiation in mice.

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Vitamin E-gene interactions in aging and inflammatory age-related diseases: Implications for treatment. A systematic review.

Mocchegiani E, Costarelli L, Giacconi R, Malavolta M, Basso A, Piacenza F, Ostan R, Cevenini E, Gonos ES, Franceschi C, Monti D.

Aging is a complex biological phenomenon in which the deficiency of the nutritional state combined with the presence of chronic inflammation and oxidative stress contribute to the development of many age-related diseases. Under this profile, the free radicals produced by the oxidative stress lead to a damage of DNA, lipids and proteins with subsequent altered cellular homeostasis and integrity. In young-adult age, the cell has a complex efficient system to maintain a proper balance between the levels of free radicals and antioxidants ensuring the integrity of cellular components. In contrast, in old age this balance is poorly efficient compromising cellular homeostasis. Supplementation with Vitamin E can restore the balance and protect against the deteriorating effects of oxidative stress, progression of degenerative diseases, and aging. Experiments in cell cultures and in animals have clearly shown that Vitamin E has a pivotal role as antioxidant agent against the lipid peroxidation on cell membranes preserving the tissue cells from the oxidative damage. Such a role has been well documented in immune, endothelial, and brain cells from old animals describing how the Vitamin E works both at cytoplasmatic and nuclear levels with an influence on many genes related to the inflammatory/immune response. All these findings have supported a lot of clinical trials in old humans and in inflammatory age-related diseases with however contradictory and inconsistent results and even indicating a dangerous role of Vitamin E able to affect mortality. Various factors can contribute to all the discrepancies. Among them, the doses and the various isoforms of Vitamin E family (α,β,γ,δ tocopherols and the corresponding tocotrienols) used in different trials. However, the more plausible gap is the poor consideration of the Vitamin E-gene interactions that may open new roadmaps for a correct and personalized Vitamin E supplementation in aging and age-related diseases with satisfactory results in order to reach healthy aging and longevity. In this review, this peculiar nutrigenomic and/or nutrigenetic aspect is reported and discussed at the light of specific polymorphisms affecting the Vitamin E bioactivity.

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Bioavailability of tocotrienols: evidence in human studies.

Fu JY, Che HL, Tan DM, Teng KT.

As a minor component of vitamin E, tocotrienols were evident in exhibiting biological activities such as neuroprotection, radio-protection, anti-cancer, anti-inflammatory and lipid lowering properties which are not shared by tocopherols. However, available data on the therapeutic window of tocotrienols remains controversial. It is important to understand the absorption and bioavailability mechanisms before conducting in-depth investigations into the therapeutic efficacy of tocotrienols in humans. In this review, we updated current evidence on the bioavailability of tocotrienols from human studies. Available data from five studies suggested that tocotrienols may reach its target destination through an alternative pathway despite its low affinity for α-tocopherol transfer protein. This was evident when studies reported considerable amount of tocotrienols detected in HDL particles and adipose tissues after oral consumption. Besides, plasma concentrations of tocotrienols were shown to be higher when administered with food while self-emulsifying preparation of tocotrienols was shown to enhance the absorption of tocotrienols. Nevertheless, mixed results were observed based on the outcome from 24 clinical studies, focusing on the dosages, study populations and formulations used. This may be due to the variation of compositions and dosages of tocotrienols used, suggesting a need to understand the formulation of tocotrienols in the study design. Essentially, implementation of a control diet such as AHA Step 1 diet may influence the study outcomes, especially in hypercholesterolemic subjects when lipid profile might be modified due to synergistic interaction between tocotrienols and control diet. We also found that the bioavailability of tocotrienols were inconsistent in different target populations, from healthy subjects to smokers and diseased patients. In this review, the effect of dosage, composition and formulation of tocotrienols as well as study populations on the bioavailability of tocotrienols will be discussed.

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Novel liquid chromatography-mass spectrometry method shows that vitamin E deficiency depletes arachidonic and docosahexaenoic acids in zebrafish (Danio rerio) embryos.

To test the hypothesis that embryogenesis depends upon α-tocopherol (E) to protect embryo polyunsaturated fatty acids (PUFAs) from lipid peroxidation, new methodologies were applied to measure α-tocopherol and fatty acids in extracts from saponified zebrafish embryos. A solid phase extraction method was developed to separate the analyte classes, using a mixed mode cartridge (reverse phase, π-π bonding, strong anion exchange), then α-tocopherol and cholesterol were measured using standard techniques, while the fatty acids were quantitated using a novel, reverse phase liquid chromatography-mass spectrometry (LC-MS) approach. We also determined if α-tocopherol status alters embryonic lipid peroxidation products by analyzing 24 different oxidized products of arachidonic or docosahexaenoic (DHA) acids in embryos using LC with hybrid quadrupole-time of flight MS. Adult zebrafish were fed E- or E+ diets for 4 months, and then were spawned to obtain E- and E+ embryos. Between 24 and 72 hours post-fertilization (hpf), arachidonic acid decreased 3-times faster in E- (21 pg/h) compared with E+ embryos (7 pg/h, P<0.0001), while both α-tocopherol and DHA concentrations decreased only in E- embryos. At 36 hpf, E- embryos contained double the 5-hydroxy-eicosatetraenoic acids and 7-hydroxy-DHA concentrations, while other hydroxy-lipids remained unchanged. Vitamin E deficiency during embryogenesis depleted DHA and arachidonic acid, and increased hydroxy-fatty acids derived from these PUFA, suggesting that α-tocopherol is necessary to protect these critical fatty acids.

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Vitamin E-gene interactions in ageing and inflammatory age-related diseases: implications for treatment. A systematic review.

Mocchegiani E, Costarelli L, Giacconi R, Malavolta M, Basso A, Piacenza F, Ostan R, Cevenini E, Gonos ES, Franceschi C, Monti D

Aging is a complex biological phenomenon in which the deficiency of the nutritional state combined with the presence of chronic inflammation and oxidative stress contribute to the development of many age-related diseases. Under this profile, the free radicals produced by the oxidative stress lead to a damage of DNA, lipids and proteins with subsequent altered cellular homeostasis and integrity. In young-adult age, the cell has an complex efficient system to maintain a proper balance between the levels of free radicals and antioxidants ensuring the integrity of cellular components. In contrast, in old age this balance is poorly efficient compromising cellular homeostasis. Supplementation with Vitamin E can restore the balance and protect against the deteriorating effects of oxidative stress, progression of degenerative diseases, and ageing. Experiments in cell cultures and in animals have clearly shown that Vitamin E has a pivotal role as antioxidant agent against the lipid peroxidation on cell membranes preserving the tissue cells from the oxidative damage. Such a role has been well documented in immune, endothelial, and brain cells from old animals describing how the Vitamin E works both at cytoplasmatic and nuclear levels with an influence on many genes related to the inflammatory/immune response. All these findings have supported a lot of clinical trials in old humans and in inflammatory age-related diseases with however contradictory and inconsistent results and even indicating a dangerous role of Vitamin E able to affect mortality. Various factors can contribute to all the discrepancies. Among them, the doses and the various isoforms of Vitamin E family (α,β,γ,δ tocopherols and the corresponding tocotrienols) used in different trials. However, the more plausible gap is the poor consideration of the Vitamin E-gene interactions that may open new roadmaps for a correct and personalized Vitamin E supplementation in ageing and age-related diseases with satisfactory results in order to reach healthy ageing and longevity. In this review, this peculiar nutrigenomic and/or nutrigenetic aspect is reported and discussed at the light of specific polymorphisms affecting the Vitamin E bioactivity.

Read more