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Tocotrienols

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Tuesday, 29 May 2012

ImageTocotrienols – together with tocopherols – make up the vitamin E family. Natural tocotrienols exist in four different forms or isomers, named alpha-, beta-, gamma- and delta- tocotrienol, which contain different numbers of methyl groups on the chromanol ring. Although all the isomers are important antioxidants due to the ease of donating a hydrogen atom from the hydroxyl group on the chromanol ring to reduce free radicals, each of them has its own biological activity. Furthermore, many studies on test-tube scale indicate that tocotrienols have an anti-cancer effect, especially against skin and breast cancer for the extra three unsaturated bond.

Comparison of tocotrienol and tocopherol

Both tocotrienols and tocopherols, whose derivatives are in eight different isoforms, belong to vitamin E. However, some research suggests tocotrienols are more potent in their anti-oxidation and anti-cancer effect than the common forms of tocopherol due to significant differences in chemical structure. The unsaturated side-chain in tocotrienols makes them penetrate tissues with saturated fatty layers more efficiently, making them potentially more useful for cosmetic products.
While tocopherols are generally present in common vegetable oils (i.e. soy, canola), tocotrienols, on the other hand, are concentrated in cereal grains (ie. oat, barley, and rye, rice bran), with the highest level found in crude palm oil. Commercial tocotrienols and tocopherols are mainly obtained from natural sources, such as palm or rice bran oil.

Natural tocotrienols

Food sources: Palm oil is the largest natural source of tocotrienols. Other good sources are rice bran oil, and coconut oil. Other food sources include cereal grains, such as barley, oats, and rye.
Tocotrienols can be obtained from natural sources using general procedures, labelled ‘d-tocotrienols’. Tocotrienols concentrates and isomers can be obtained through purification processes. These procedures are intricate and difficult to do on a large scale. However, some companies may have achieved a breakthrough in isolating and purifying natural tocotrienols.

Synthetic tocotrienols

Although not currently available, tocotrienols can be synthesized through chemical reactions, labelled ‘dl-tocotrienols’. Chemically synthesized tocotrienols consist of both normal and its laterally inverted compounds, which are a mirror-reflection of each other. The left version has the same structure but is laterally inverted to the right version.


Possible health benefits of tocotrienols

Tocotrienols and stroke-induced Injuries
In the peer-reviewed Stroke journal (Oct 2005), oral supplementation of a natural full spectrum palm tocotrienol complex to spontaneously hypertensive rats led to increased tocotrienols level in the brain. The rats supplemented with tocotrienols showed more protection against stroke-induced injury compared to controls (non-supplemented group). This study demonstrated that oral supplementation of the palm tocotrienol complex acts on key molecular checkpoints (c-Src and 12-Lipoxygenase) to protect against glutamate- and stroke-induced neurodegeneration and ultimately may protect against stroke in vivo. (Sen, CK, et al., “Neuroprotective Properties of the Natural Vitamin E Alpha-Tocotrienol”, Stroke, 2005; 36:e 144 – e 152)

Tocotrienols and reversal of arterial blockage in carotid stenosis patients
Palm tocotrienol complex has been shown in a double-blind placebo controlled human study conducted at the Kenneth Jordan Heart Foundation (NJ, US) to have the ability to reverse arteriosclerosis. Palm tocotrienol complex has the ability to reverse arterial blockage of the carotid artery in Carotid Stenosis patients.

Antioxidant activity
Antioxidants include polyphenols, lipoic acid, carotenoids, and tocotrienols. These 'nutraceuticals' have demonstrated greater antioxidant and anti-cancer activity than what has been achieved previously in nutritional protocols and cosmetics formulas. The benefits of tocotrienols range from decreasing platelet aggregation (clumping of blood) to anti-inflammatory action and anti-cancer activity.

Tocotrienols show considerably superior antioxidant properties compared to dl-α-Tocopherol in clinical and experimental studies due to their better distribution in the fatty layers of the cell membrane. The tocotrienol unsaturated side chain allows for a more efficient penetration into saturated fatty layers of the brain and liver. In addition to the free radical scavenging effect, the antioxidant function of tocotrienols is also associated with lowering tumor formation, DNA damage and cell damage. Studies in animals explored the effects of long-term administration of tocotrienols on liver cancer. Supplementation of tocotrienols in rats induced with a potent liver cancer agent demonstrated that the tocotrienols prolonged the impact of the cancer agent. Cell damage to the liver was significant in the untreated group versus the tocotrienol treated group.

Tocotrienols and breast cancer
A study showed that tocotrienols are the components of vitamin E responsible for growth inhibition in human breast cancer cells in vitro as well as in vivo through estrogen-independent mechanisms. Tocotrienols can also affect cell homeostasis, possibly independently of their antioxidant activity.[1] Anti-cancer effects of α- and γ-tocotrienol have been reported, although δ-tocotrienol was verified to be the most effective tocotrienol in inducing apoptosis (cell death) in estrogen-responsive and estrogen-nonresponsive human breast cancer cells. A daily dose of 30 - 50 mg mixture of α- and γ-tocotrienols can reduce breast cancer risk, and a treatment plan for breast cancer should use higher dosage.

Tocotrienols and prostate cancer
Investigation of the antiproliferative effect of tocotrienols in PC3 and LNCaP prostate cancer cells suggests that the transformation of vitamin E to CEHC is mostly a detoxification mechanism, useful in maintaining the malignant properties of prostate cancer cells.[2]

Tocotrienols and cholesterol reduction
The development of new cholesterol-lowering agents has been given more and more attention by pharmaceutical companies due to the strong relationship between cholesterol and atherosclerosis. Tocotrienols, especially δ- and γ-tocotrienols, were shown to be effective nutritional agents to treat high cholesterol in recent research programs. In particular, γ-tocotrienol appears to act on a specific enzyme called 3-hydroxy-3-methylglutaryl-coenzyme and suppressed the production of this enzyme, which results in less cholesterol being manufactured by liver cells.  The investigation of the cholesterol-lowering effects of tocotrienols in cholesterol-fed rabbits found that the cholesterol in plasma decreased following gamma-tocotrienol treatment (-22%) after 6 weeks. The decrease was mainly attributable to a reduction in LDL cholesterol (23%).[3]

Tocotrienols and diabetes
Investigation of the intake of antioxidants for its ability to prevent type 2 diabetes shows that vitamin E intake was significantly associated with a reduced risk of type 2 diabetes. The relative risk (RR) of type 2 diabetes between the extreme quartiles of the intake was 0.69 (95% CI 0.51-0.94, P for trend=0.003). Intakes of alpha-tocopherol, gamma-tocopherol, delta-tocopherol, and beta-tocotrienol were inversely related to a risk of type 2 diabetes. Thus the development of type 2 diabetes may be reduced by the intake of antioxidants in the diet.[4]

References

  1. ^ Nesaretnam K, Ambra R, Selvaduray KR, et al. (2004). Tocotrienol-rich fraction from palm oil and gene expression in human breast cancer cells. ANNALS OF THE NEW YORK ACADEMY OF SCIENCES 1031: 143-157.
  2. ^ Conte C, Floridi A, Aisa C, et al. (2004). Gamma-Tocotrienol metabolism and antiproliferative effect in prostate cancer cells. ANNALS OF THE NEW YORK ACADEMY OF SCIENCES 1031: 391-394.
  3. ^ Hasselwander O, Kramer K, Hoppe PP, et al. (2002). Effects of feeding various tocotrienol sources on plasma lipids and aortic atherosclerotic lesions in cholesterol-fed rabbits. FOOD RESEARCH INTERNATIONAL 35 (2-3): 245-251.
  4. ^ Montonen J, Knekt P, Jarvinen R, et al. (2004). Dietary antioxidant intake and risk of type 2 diabetes. DIABETES CARE 27 (2): 362-366.

 

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