Multifaceted role of tocotrienols in cardioprotection supports their structure: function relation

Tocotrienols are a class of vitamin E which modulates several mechanisms associated with cardioprotection, anti-cancer, anti-diabetic, and neuroprotection. Unlike other Vitamin E-like compounds, tocotrienols possess inimitable properties. Quite a lot of studies have determined the cardioprotective abilities of tocotrienols and have been shown to possess novel hypocholesterolemic effects together with an ability to reduce the atherogenic apolipoprotein and lipoprotein plasma levels. In addition, tocotrienol has been suggested to have an antioxidant, anti-thrombotic, and anti-tumor effect indicating that tocotrienol may serve as an effective agent in the prevention and/or treatment of cardiovascular disease and cancer. The bioactivity exhibited is due to the structural characteristics of tocotrienols. Rich sources of tocotrienols which include rice bran, palm oil, and other edible oils exhibit protective effect against cardiovascular disorders. The conclusions drawn from the early literature that vitamin E group of compounds provides an inevitable role in cardioprotection is sustained in many more recent studies.     

Tocotrienols in health and disease: the other half of the natural vitamin E family

Tocochromanols encompass a group of compounds with vitamin E activity essential for human nutrition. Structurally, natural vitamin E includes eight chemically distinct molecules: -, β-, γ- and δ-tocopherol; and -, β-, γ- and δ-tocotrienol. Symptoms caused by -tocopherol deficiency can be alleviated by tocotrienols. Thus, tocotrienols may be viewed as being members of the natural vitamin E family not only structurally but also functionally. Palm oil and rice bran oil represent two major nutritional sources of natural tocotrienol. Taken orally, tocotrienols are bioavailable to all vital organs. The tocotrienol forms of natural vitamin E possesses powerful hypocholesterolemic, anti-cancer and neuroprotective properties that are often not exhibited by tocopherols. Oral tocotrienol protects against stroke-associated brain damage in vivo. Disappointments with outcomes-based clinical studies testing the efficacy of -tocopherol need to be handled with caution and prudence recognizing the untapped opportunities offered by the other forms of natural vitamin E. Although tocotrienols represent half of the natural vitamin E family, work on tocotrienols account for roughly 1% of the total literature on vitamin E. The current state of knowledge warrants strategic investment into investigating the lesser known forms of vitamin E.     

Distillation Time as Tool for Improved Antimalarial Activity and Differential Oil Composition of Cumin Seed Oil

A steam distillation extraction kinetics experiment was conducted to estimate essential oil yield, composition, antimalarial, and antioxidant capacity of cumin (Cuminum cyminum L.) seed (fruits). Furthermore, regression models were developed to predict essential oil yield and composition for a given duration of the steam distillation time (DT). Ten DT durations were tested in this study: 5, 7.5, 15, 30, 60, 120, 240, 360, 480, and 600 min. Oil yields increased with an increase in the DT. Maximum oil yield (content, 2.3 g/100 seed), was achieved at 480 min; longer DT did not increase oil yields. The concentrations of the major oil constituents α-pinene (0.14–0.5% concentration range), β-pinene (3.7–10.3% range), γ-cymene (5–7.3% range), γ-terpinene (1.8–7.2% range), cumin aldehyde (50–66% range), α-terpinen-7-al (3.8–16% range), and β-terpinen-7-al (12–20% range) varied as a function of the DT. The concentrations of α-pinene, β-pinene, γ-cymene, γ-terpinene in the oil increased with the increase of the duration of the DT; α-pinene was highest in the oil obtained at 600 min DT, β-pinene and γ-terpinene reached maximum concentrations in the oil at 360 min DT; γ-cymene reached a maximum in the oil at 60 min DT, cumin aldehyde was high in the oils obtained at 5–60 min DT, and low in the oils obtained at 240–600 min DT, α-terpinen-7-al reached maximum in the oils obtained at 480 or 600 min DT, whereas β-terpinen-7-al reached a maximum concentration in the oil at 60 min DT. The yield of individual oil constituents (calculated from the oil yields and the concentration of a given compound at a particular DT) increased and reached a maximum at 480 or 600 min DT. The antimalarial activity of the cumin seed oil obtained during the 0–5 and at 5–7.5 min DT timeframes was twice higher than the antimalarial activity of the oils obtained at the other DT. This study opens the possibility for distinct marketing and utilization for these improved oils. The antioxidant capacity of the oil was highest in the oil obtained at 30 min DT and lowest in the oil from 360 min DT. The Michaelis-Menton and the Power nonlinear regression models developed in this study can be utilized to predict essential oil yield and composition of cumin seed at any given duration of DT and may also be useful to compare previous reports on cumin oil yield and composition. DT can be utilized to obtain cumin seed oil with improved antimalarial activity, improved antioxidant capacity, and with various compositions.     

生育三烯酚的生理功能及合成代谢调控

维生素E是一种重要的脂溶性抗氧化剂。天然维生素E包括α-、β-、γ-和δ-生育酚及α-、β-、γ-和δ-生育三烯酚等8种组分。生育三烯酚具有独特的降低胆固醇、抗癌和神经保护功能,这些功能是生育酚所不具备的。生育三烯酚主要由谷物等单子叶植物合成。虽然生育三烯酚成分占天然维生素E的一半,但有关生育三烯酚的研究仅占维生素E全部文献的1%。可喜的是,近年来这一领域的研究取得了较大的进展。我们就生育三烯酚在人体内的生理功能、来源、生物合成及代谢调控等方面的进展进行概述。     

A naturally occurring mixture of tocotrienols inhibits the growth of human prostate tumor,associated with epigenetic modifications of cyclin-dependent kinase inhibitors p21 and p27

Tocotrienols, members of the vitamin E family, have three unsaturated bonds in their side chains. Recently, it has been suggested that the biological effects of tocotrienols may differ from that of tocopherols. Several in vitro studies have shown that tocotrienols have stronger anticancer effects than tocopherols. VCaP cell line used in this study is from a vertebral bone metastasis from a patient with prostate cancer. Eight-week-old male NCr(−/−) nude mice were subcutaneously injected with VCaP-luc cells in matrigel and then administered a tocotrienol mixture for 8 weeks. The tocotrienol mixture inhibited the growth of human prostate tumor xenografts in a dose-dependent manner. The concentrations of tocotrienols and their metabolites were significantly increased in treatment groups. Tocotrienols inhibited prostate tumor growth by suppressing cell proliferation, which was associated with the induction of the cyclin-dependent kinase (CDK) inhibitors p21 and p27. In addition, tocotrienol treatment was associated with elevated H3K9 acetylation levels at proximal promoter regions of p21 and p27 and with decreased expression of histone deacetylases. Tocotrienols inhibited human prostate tumor growth, associated with up-regulation of the CDK inhibitors p21 and p27. Elevated expression of p21 and p27 could be partly due to the suppressed expression of HDACs.     

Tocotrienols promote apoptosis in human breast cancer cells by inducing poly(ADP‐ribose) polymerase cleavage and inhibiting nuclear factor kappa‐B activity

Objectives

Tocotrienols and tocopherols are members of the vitamin E family, with similar structures; however, only tocotrienols have been reported to achieve potent anti‐cancer effects. The study described here has evaluated anti‐cancer activity of vitamin E to elucidate mechanisms of cell death, using human breast cancer cells.

Materials and methods

Anti‐cancer activity of a tocotrienol‐rich fraction (TRF) and a tocotrienol‐enriched fraction (TEF) isolated from palm oil, as well as pure vitamin E analogues (α‐tocopherol, α?, δ? and γ?tocotrienols) were studied using highly aggressive triple negative MDA‐MB‐231 cells and oestrogen‐dependent MCF‐7 cells, both of human breast cancer cell lines. Cell population growth was evaluated using a Coulter particle counter. Cell death mechanism, poly(ADP‐ribose) polymerase cleavage and levels of NF‐κB were determined using commercial ELISA kits.

Results

Tocotrienols exerted potent anti‐proliferative effects on both types of cell by inducing apoptosis, the underlying mechanism of cell death being ascertained using respective IC₅₀ concentrations of all test compounds. There was marked induction of apoptosis in both cell lines by tocotrienols compared to treatment with Paclitaxel, which was used as positive control. This activity was found to be associated with cleavage of poly(ADP‐ribose) polymerase (a DNA repair protein), demonstrating involvement of the apoptotic cell death signalling pathway. Tocotrienols also inhibited expression of nuclear factor kappa‐B (NF‐κB), which in turn can increase sensitivity of cancer cells to apoptosis.

Conclusion

Tocotrienols induced anti‐proliferative and apoptotic effects in association with DNA fragmentation, poly(ADP‐ribose) polymerase cleavage and NF‐κB inhibition in the two human breast cancer cell lines.

     

Effects of Late Administration of Pentoxifylline and Tocotrienols in an Image-Guided Rat Model of Localized Heart Irradiation

Radiation-induced heart disease (RIHD) is a long-term side effect of radiotherapy of intrathoracic, chest wall and breast tumors when radiation fields encompass all or part of the heart. Previous studies have shown that pentoxifylline (PTX) in combination with α-tocopherol reduced manifestations of RIHD in rat models of local heart irradiation. The relative contribution of PTX and α-tocopherol to these beneficial effects are not known. This study examined the effects of PTX alone or in combination with tocotrienols, forms of vitamin E with potential potent radiation mitigation properties. Rats received localized X-irradiation of the heart with an image-guided irradiation technique. At 3 months after irradiation rats received oral treatment with vehicle, PTX, or PTX in combination with a tocotrienol-enriched formulation. At 6 months after irradiation, PTX-treated rats showed arrhythmia in 5 out of 14 animals. PTX alone or in combination with tocotrienols did not alter cardiac radiation fibrosis, left ventricular protein expression of the endothelial markers von Willebrand factor and neuregulin-1, or phosphorylation of the signal mediators Akt, Erk1/2, or PKCα. On the other hand, tocotrienols reduced cardiac numbers of mast cells and macrophages, but enhanced the expression of tissue factor. While this new rat model of localized heart irradiation does not support the use of PTX alone, the effects of tocotrienols on chronic manifestations of RIHD deserve further investigation.     

Comparison of Chemical Profile and Antioxidant Capacity of Seeds and Oils from Salvia sclarea and Salvia officinalis

Composition of tocopherols, tocotrienols, carotenoids, fatty acids, as well as hydrophilic and lipophilic antioxidant activities, were determined in seeds of two Salvia species and oils obtained from them. Both seeds contained a large amount of oil (around 20%) rich in polyunsaturated fatty acids. While Salvia officinalis seed oil can be classified as oleic‐linoleic oil, the predominant fatty acid in Salvia sclarea was α‐linolenic acid (around 54%). Among tocols, the main isomers in both seeds and oils were γ‐tocopherol, followed by α‐tocopherol. Concerning carotenoids, their concentration was around 0.75 mg/100 g of seeds and 0.16 mg/100 g of oils, with a predominance of lutein. Oil and seeds of S. officinalis exhibited higher antioxidant potential compared to S. sclarea investigated samples which could be attributed to higher content of total vitamin E and carotenoids. This study provides results that enables use of two Salvia species as new alternative sources of vegetable oils.     

Metabolic engineering of soybean seeds for enhanced vitamin E tocochromanol content and effects on oil antioxidant properties in polyunsaturated fatty acid-rich germplasm

Soybean seeds produce oil enriched in oxidatively unstable polyunsaturated fatty acids (PUFAs) and are also a potential biotechnological platform for synthesis of oils with nutritional omega-3 PUFAs. In this study, we engineered soybeans for seed-specific expression of a barley homogentisate geranylgeranyl transferase (HGGT) transgene alone and with a soybean γ-tocopherol methyltransferase (γ-TMT) transgene. Seeds for HGGT-expressing lines had 8- to 10-fold increases in total vitamin E tocochromanols, principally as tocotrienols, with little effect on seed oil or protein concentrations. Tocochromanols were primarily in δ- and γ-forms, which were shifted largely to α- and β-tocochromanols with γ-TMT co-expression. We tested whether oxidative stability of conventional or PUFA-enhanced soybean oil could be improved by metabolic engineering for increased vitamin E antioxidants. Selected lines were crossed with a stearidonic acid (SDA, 18:4^Δ6,9,12,15)-producing line, resulting in progeny with oil enriched in SDA and α- or γ-linoleic acid (ALA, 18:3^Δ9,12,15 or GLA, 18:3^Δ6,9,12), from transgene segregation. Oil extracted from HGGT-expressing lines had ≥6-fold increase in free radical scavenging activity compared to controls. However, the oxidative stability index of oil from vitamin E-enhanced lines was ~15% lower than that of oil from non-engineered seeds and nearly the same or modestly increased in oil from the GLA, ALA and SDA backgrounds relative to controls. These findings show that soybean is an effective platform for producing high levels of free-radical scavenging vitamin E antioxidants, but this trait may have negative effects on oxidative stability of conventional oil or only modest improvement of the oxidative stability of PUFA-enhanced oil.     

七种植物籽油中脂肪酸成分的比较分析(英文)

为寻求新的食用油资源,发展了一种快速可靠的气相色谱-质谱联用方法,用于植物籽油中脂肪酸成分的定性鉴定和含量测定。所建立的方法成功用于葡萄籽、南瓜籽和猕猴桃籽等七种植物籽油中的棕榈酸、十八烷酸、油酸、亚油酸和α-亚麻酸的定性定量分析。结果表明,刺葡萄籽油、普通葡萄籽油、国外葡萄籽油、南瓜籽油、枸杞籽油和西番莲籽油均具有相似的脂肪酸谱,尽管其中它们所含上述五种脂肪酸含量不同,由于均存在人体所必需的饱和与不饱和脂肪酸,故可以用作替代食用油。猕猴桃籽油因为其存在高含量的α-亚麻酸成分,可能是更好的食用油和营养油资源。本文首次对枸杞籽油、西番莲籽油和猕猴桃籽油脂肪酸成分进行绝对含量分析,为新的食用油资源的开发提供了重要的依据。     

Inhibitory effect of tocotrienol on eukaryotic DNA polymerase lambda and angiogenesis

Tocotrienols, vitamin E compounds that have an unsaturated side chain with three double bonds, selectively inhibited the activity of mammalian DNA polymerase lambda (pol lambda) in vitro. These compounds did not influence the activities of replicative pols such as alpha, delta, and epsilon, or even the activity of pol beta which is thought to have a very similar three-dimensional structure to the pol beta-like region of pol lambda. Since delta-tocotrienol had the strongest inhibitory effect among the four (alpha- to delta-) tocotrienols, the isomer's structure might be an important factor in the inhibition of pol lambda. The inhibitory effect of delta-tocotrienol on both intact pol lambda (residues 1-575) and a truncated pol lambda lacking the N-terminal BRCA1 C-terminus (BRCT) domain (residues 133-575, del-1 pol lambda) was dose-dependent, with 50% inhibition observed at a concentration of 18.4 and 90.1microM, respectively. However, del-2 pol lambda (residues 245-575) containing the C-terminal pol beta-like region was unaffected. Tocotrienols also inhibited the proliferation of and formation of tubes by bovine aortic endothelial cells, with delta-tocotrienol having the greatest effect. These results indicated that tocotrienols targeted both pol lambda and angiogenesis as anti-cancer agents. The relationship between the inhibition of pol lambda and anti-angiogenesis by delta-tocotrienol was discussed.     

Antioxidant and Antibacterial Activities of Crude Extracts and Essential Oils of Syzygium cumini Leaves

This research highlights the chemical composition, antioxidant and antibacterial activities of essential oils and various crude extracts (using methanol and methylene chloride) from Syzygium cumini leaves. Essential oils were analyzed by gas chromatography-mass spectrometry (GC-MS).The abundant constituents of the oils were: α-pinene (32.32%), β-pinene (12.44%), trans-caryophyllene (11.19%), 1, 3, 6-octatriene (8.41%), delta-3-carene (5.55%), α-caryophyllene (4.36%), and α-limonene (3.42%).The antioxidant activities of all extracts were examined using two complementary methods, namely diphenylpicrylhydrazyl (DPPH) and ferric reducing power (FRAP). In both methods, the methanol extract exhibited a higher activity than methylene chloride and essential oil extracts. A higher content of both total phenolics and flavonoids were found in the methanolic extract compared with other extracts. Furthermore, the methanol extract had higher antibacterial activity compared to methylene chloride and the essential oil extracts. Due to their antioxidant and antibacterial properties, the leaf extracts from S. cumini may be used as natural preservative ingredients in food and/or pharmaceutical industries.     

Towards the interaction mechanism of tocopherols and tocotrienols (vitamin E) with selected metabolizing enzymes

Vitamin E is a mixture of eight compounds α, β, γ, δ­ tocopherols and α, β, γ, δ­ tocotrienols. Their individual role in cellular transport as antioxidants and in metabolic pathways has been highlighted in the present work. All the eight compounds have been docked with the respective metabolizing enzymes (α­tocopherol transfer protein (ATTP), α­tocopherol associated protein (TAP), P­glycoprotein (P­gly) and human serum albumin (HSA)) to understand molecular interactions for pharmacokinetics. These have been structurally aligned against the four human phospholipids in order to reveal their individual role in chylomicron formation and hence the mechanism of cellular transport. The study of their binding with their metabolizing enzymes provides insight to the comparative antioxidant activity of each of these isomers.     

Pilot scale production of functional foods using red palm olein: Antioxidant,vitamins’ stability and sensory quality during storage

The objective of this research work was to produce acceptable quality functional foods, namely, extruded snacks, digestive biscuits and pan bread, on a pilot scale, using vitamin E and β-carotene-rich red palm olein (RPOL) and red palm shortening (RPS). These products were evaluated for their chemical composition and sensory quality along with the antioxidants and vitamin contents during the six months of storage at room temperature (22 ± 1 °C). Extruded snacks and digestive biscuits prepared with RPOL and RPS were found to be good sources of these antioxidant vitamins. The average β-carotene content of the control and test snacks at the end of six months of storage ranged from 26.8 to 56.1 mg/kg fat, and from 430.9 to 468.9 mg/kg fat, respectively. The total vitamin E content in control and test snacks made in Plant No. 1 decreased after six months of storage from 786.1 to 704.4 mg/kg fat, and from 765.1 to 695.4 mg/kg fat, respectively. As expected, the total tocotrienol content was four to five times higher than the total tocopherols in control biscuits. The RPOL containing 600–750 ppm of carotenes (mainly α- and β-carotenes), 710–774 ppm of vitamin E, was found to be suitable for industrial application in producing acceptable quality pan bread, digestive biscuits and snacks. These functional foods contained significant amounts of β-carotene and total vitamin E, indicating the possibility of producing such foods rich in these two of the important antioxidant vitamins coming from a natural source. The research findings strongly indicate that good-quality pan bread, extruded snacks and digestive biscuits can successfully be produced to offer healthier eating choices to the consumers of this region, thereby promoting better health and productivity among the population.     

Disruption of P450-mediated vitamin E hydroxylase activities alters vitamin E status in tocopherol supplemented mice and reveals extra-hepatic vitamin E metabolism

The widely conserved preferential accumulation of α-tocopherol (α-TOH) in tissues occurs, in part, from selective postabsorptive catabolism of non-α-TOH forms via the vitamin E-ω-oxidation pathway. We previously showed that global disruption of CYP4F14, the major but not the only mouse TOH-ω-hydroxylase, resulted in hyper-accumulation of γ-TOH in mice fed a soybean oil diet. In the current study, supplementation of Cyp4f14^−/− mice with high levels of δ- and γ-TOH exacerbated tissue enrichment of these forms of vitamin E. However, at high dietary levels of TOH, mechanisms other than ω-hydroxylation dominate in resisting diet-induced accumulation of non-α-TOH. These include TOH metabolism via ω-1/ω-2 oxidation and fecal elimination of unmetabolized TOH. The ω-1 and ω-2 fecal metabolites of γ- and α-TOH were observed in human fecal material. Mice lacking all liver microsomal CYP activity due to disruption of cytochrome P450 reductase revealed the presence of extra-hepatic ω-, ω-1, and ω-2 TOH hydroxylase activities. TOH-ω-hydroxylase activity was exhibited by microsomes from mouse and human small intestine; murine activity was entirely due to CYP4F14. These findings shed new light on the role of TOH-ω-hydroxylase activity and other mechanisms in resisting diet-induced accumulation of tissue TOH and further characterize vitamin E metabolism in mice and humans.     

Suboptimal Serum α-Tocopherol Concentrations Observed among Younger Adults and Those Depending Exclusively upon Food Sources,NHANES 2003-20061-3

Vitamin E is an essential nutrient for human health, with an established function as a lipid-soluble antioxidant that protects cell membranes from free radical damage. Low vitamin E status has been linked to multiple health outcomes, including total mortality. With vitamin E being identified as a ‘shortfall nutrient’ because >90% of American adults are not consuming recommended amounts of vitamin E, we aimed to determine the prevalence of both clinical vitamin E deficiency (serum α-tocopherol concentration < 12 μmol/L) and failure to meet a criterion of vitamin E adequacy, serum α-tocopherol concentration of 30 μmol/L, based on the Estimated Average Requirement (EAR) and lowest mortality rate in the Alpha-Tocopherol Beta-Carotene (ATBC) study. The most recent nationally-representative cross-sectional data (2003–2006) among non-institutionalized US citizens with available serum concentrations of α-tocopherol from the National Health and Nutrition Examination Survey (NHANES); Centers for Disease Control and Prevention were analyzed. Serum α-tocopherol distributions were compared between those reporting consumption of food without supplement use (FOOD) and food and supplement use (FOOD+DS) by sex, age, and race/ethnicity. Only 1% of the US population is clinically deficient. FOOD consumers have lower average α-tocopherol levels (24.9± 0.2 μmol/L) than FOOD+DS users (33.7 ± 0.3 μmol/L), even when adjusted for total cholesterol. Using a criterion of adequacy of 30 μmol/L, 87% of persons 20-30y and 43% of those 51+y had inadequate vitamin E status (p<0.01). A significant greater prevalence of FOOD compared to FOOD+DS users did not meet the criterion of adequacy which was based on the EAR and low ATBC mortality rate consistently across age, sex, and race/ethnic groups. The prevalence of inadequate vitamin E levels is significantly higher among non-users of dietary supplements. With declining usage of vitamin E supplements, the population should be monitored for changes in vitamin E status and related health outcomes.     

Tocotrienols: Balancing the Mitochondrial Crosstalk Between Apoptosis and Autophagy

Tocotrienols are a group of natural vitamin E compounds with patent antitumoral effects, mostly based on their ability to induce apoptosis in cancer cells. In activated pancreatic stellate cells (PSCs) we have determined that tocotrienols elicit a dramatic mitochondrial destabilization followed by initiation of non-necrotic forms of programmed cell death, namely apoptosis and autophagy. PSCs are the main cell type involved in the generation of pancreatic fibrosis, and their removal is critical to limit the fibrogenic process. Noteworthy, tocotrienol death-promoting actions are exclusively directed to activated PSCs, but not to their quiescent counterparts nor to terminally differentiated acinar cells. Here, we hypothesize that the transformed phenotype of PSCs may include “activated” mitochondria, which can be used by tocotrienols to trigger autophagic and apoptotic signaling. We propose that mitochondria are the cornerstone of cell sensitivity to tocotrienols, and suggest possible mechanisms, that may be interconnected, on how tocotrienols may govern mitochondrial death pathways.

Addendum to:

Tocotrienols Induce Apoptosis and Autophagy in Rat Pancreatic Stellate Cells through the Mitochondrial Death Pathway

M. Rickmann, E.C. Vaquero, J.R. Malagelada and X. Molero

Gastroenterology 2007; 132:2518-32     

Ultrasonic-Assisted Extraction of Raspberry Seed Oil and Evaluation of Its Physicochemical Properties,Fatty Acid Compositions and Antioxidant Activities

Ultrasonic-assisted extraction was employed for highly efficient separation of aroma oil from raspberry seeds. A central composite design with two variables and five levels was employed and effects of process variables of sonication time and extraction temperature on oil recovery and quality were investigated. Optimal conditions predicted by response surface methodology were sonication time of 37 min and extraction temperature of 54°C. Specifically, ultrasonic-assisted extraction (UAE) was able to provide a higher content of beneficial unsaturated fatty acids, whereas conventional Soxhlet extraction (SE) resulted in a higher amount of saturated fatty acids. Moreover, raspberry seed oil contained abundant amounts of edible linoleic acid and linolenic acid, which suggest raspberry seeds could be valuable edible sources of natural γ-linolenic acid products. In comparison with SE, UAE exerted higher free radical scavenging capacities. In addition, UAE significantly blocked H₂O₂-induced intracellular reactive oxygen species (ROS) generation.