Tocotrienols effects

Tocotrienols, gamma Oryzanol Phosphatidyl chohne Antioxidants Controls liver cirrhosis and helps in effective liver detoxification (Bruni, 1988). Protectant against hver damage (Kidd, 1996). Antioxidant enzymes prevent hpid peroxidation and helps protecting the liver cells from damage. 

Tocotrienols are another group of phytochemicals of rice bran which have a chemopreventive effect and have been demonstrated to inhibit breast cancer (Nesaremam et al., 1998). The polysaccharides of rice bran contain a-glucan, the anti-tumor effect of which has been demonstrated by its inhibition of gastrointestinal carcinogenesis (Akeshita et al., 1992). Rice bran agglutinin has been shown to induce apoptosis of cancer cells by the mechanism of cell cycle dysregulation (Miyoshi et al., 2001). 

QURESHI A A, SAMI s A, SALSER w A, KHAN F A (2001) Syuergistic effect of tocotrienol rich fraction (TRF 25) of rice bran and lovostatin on lipid parameters in hypercholesterolemic hamnns. J Nutri Biochem, 12 318-29. 

RAEDERSTORFF D, ELSTE V, AEBiscHER c, WEBER p (2002) Effect of either gamma-tocotrienol or a tocotrienol mixture on the plasma lipid profile in hamsters. Ann Nutr Metab, 46 17-23. 

TOMEO A c, GELLER M (1995) Antioxidant effect of tocotrienols in patients with hyperlipidemia and carotid stenosis. Lipids, 30 1179-83. 

Halliwell B, Rafter J and Jenner A (2005), Health promotion by flavonoids, tocopherols, tocotrienols, and other phenols direct or indirect effects Antioxidant or not , Am J Clin Nutr, 81 (Suppl), 268S-276S. 

The molecular target site of triketone herbicides is the enzyme -hydroxyphenylpyruvate dioxygenase (HPPD). Inhibition of this enzyme disrupts the biosynthesis of carotenoids and causes a bleaching (loss of chlorophyll) effect on the foliage similar to that observed with inhibitors ofphytoene desaturase (e.g. norflurazon). However, the mechanism of action of HPPD inhibitors is different. Inhibtion of HPPD stops the synthesis of homogen tisate (HGA), which is a key precursor of the 8 different tocochromanols (tocopherols and tocotrienols) and prenyl quinones. In the absence of prenylquinone plastoquinone, phytoene desaturase activity is interrupted. The bleaching of the green tissues ensues as if these compounds inhibited phytoene desaturase. 

Saponification. Before solvent is added for extraction, saponification (alkaline hydrolysis) is a step used in most extractions of tocopherols and tocotrienols. It should be noted that acetate forms of tocopherols or tocotrienols in a sample are changed to free tocopherols and tocotrienols after saponification. This process breaks down the ester bonds of lipids and sample matrices as well. In most extraction procedures, a 60% to 80% (w/v) aqueous solution of KOH is used to perform the saponification. The volume of KOH required varies according to the amount of lipid contained in the sample. Also, ethanol is needed to stabilize the saponified solution and prevent the precipitation of soap material. Usually, the ratio of KOH, ethanol, and fat (in sample) during saponification is 3 (g) 15 (ml) 1 (g), respectively (Ball, 1988). The ratio may need to be adjusted based on the types of fats in the sample. Although ethanol concentration has no effect on the extraction of a-tocopherol by hexane, a concentration above 30% may cause lower recoveries of other tocopherols (Ueda and Igarashi, 1990). For most food samples, saponification for 30 min at70°C is sufficient. 

In reversed-phase HPLC on a Cl8 column, only six peaks are usually found, and their order of elution is 5-tocotrienol, (3- and y-to-cotrienols, a-tocotrienol, 5-tocopherol, (3- and y-tocopherol, and a-tocopherol. Figure D 1.5.4 is an example of a reversed-phase chromatograph of tocopherols and tocotrienols in rice bran oil. The tocols with unsaturated side chain have shorter retention time than those with saturated side chain. The methyl substituents on the chromanol ring also affect the retention times of tocopherols and tocotrienols. However, the effect is reversed, compared with the normal-phase HPLC method. 

Valencia oil. see Citrus Orange Valine, hydrolysis, effect on, 134 Vapor pressure, 4. see Water activity Vapor pressure manometer (VPM), 61 -66 Vegetable oils characteristics of, 525 refined, tocopherol/tocotrienol... 

Tocopherols consist of a, (3, y, and 8 isomers and are effective antioxidants. Oomah et al. (1997a) observed that y-tocopherol (9.04 mg/100 g seed) was the predominant isomer of Canadian flaxseed cultivars. Total tocopherol ( r = 0.42) and y-tocopherol (r = 0.41) values were correlated with seed oil content. Kamm et al. (2001) reported the distribution of tocopherols and tocotrienols in high and low linolenic flaxseed. Results were similar to the findings of Oomah et al. (1997a) in which y-tocopherol content was greater (430-575 mg/kg oil) in high ALA flaxseeds, whereas low linolenic flaxseed exhibited lower (170 mg/kg oil) values. Bozan and Temelli (2002) compared tocopherol levels in oil extracted by supercritical C02 fluid and soxhlet (Table XI). Soxhlet-extracted oil had greater tocopherol levels (76.4 mg/100 g oil). These authors speculated that the temperature-pressure combination may have influenced the tocopherol extraction by supercritical C02 fluid. 

N5. Newaz, M. A., and Nawal, N. N., Effect of gamma-tocotrienol on blood pressure, lipid peroxidation and total antioxidant status in spontaneously hypertensive rats (SHR). Clin. Exp. Flypertens. 

Vitamin E is an effective scavenger of lipid peroxy radicals and is efficient at protecting unsaturated fatty acids against lipid peroxidation. The chemistry of vitamin E is rather complex as there are eight compounds, four tocopherols and four tocotrienols, which exhibit vitamin E activity. The relative bioactivity of the various compounds varies considerably, from 1.0 for a-tocopherol to 0.03 for 8-tocopherol. In milk, a-tocopherol accounts for virtually all of vitamin E, although very small amounts of (3-tocopherols and y-tocopherols are present. Also, the concentration of a-tocopherol in milk fat varies widely, with the level in samples of commercial butter ranging from 18 to 35 pg/g fat (MAFF, 1999). These concentrations equate to a low level of vitamin E bioactivity, 0.025 to 0.05 IU/g fat. 

Bergman, C.J. Xu, Z. 2003. Genotype and environment effects on tocopherol, tocotrienol, and y-oryzanol contents of southern U.S. rice. Cereal Chem. 80 446-449. 

Wang, C. Ning, J. Krishnan, P. Matthees, D. 1998. Effects of steeping conditions during wet-milling on the retention of tocopherols and tocotrienols in com. J. Am. Oil Chem. 75 609-613. 

Yoshida, Y. Niki, E. Noguchi, N. 2003. Comparative study on the action of tocopherols and tocotrienols as antioxidant chemical and physical effects. Chem. Phys. Lipids. 123 63-75. 

It was noted in Section 4.1 that the tocotrienols can be considered to be derivatives of mevalonate, the product of HMG CoA reductase, which is the key regulatory enzyme of cholesterol synthesis. Dietary tocotrienols have a cholesterol-lowering effect they act by reducing the activity of HMG CoA reductase. The main effect is posttranslational tocotrienols cause an increased... 

Kerckhoffs, D.A. et al., Effects on the human serum lipoprotein profile of p-glucan, soy protein and isoflavones, plant sterols and stanols, garlic and tocotrienols, J. Nutr, 132, 2494, 2002. 

Tocopherols and tocotrienols, collectively known as tocols, are monophenolic and lipophilic compounds that are widely distributed in plant tissues (7). The main commercial source of natural tocopherols is the soybean oil. Tocotrienols, less common than tocopherols, are present in palm oil, rice bran oil, as well as cereals and legumes (11). Tocopherols and tocotrienols are classified into a-, (3-, y-, and 5-, depending on their chemical structures (Figure 7). In general, tocotrienols have a stronger antioxidant effect on lipid oxidation than tocopherols. The antioxidant activity of tocopherols is dependent on temperature and is in the order of 5- > y->P-> oc-tocopherol (7). Tocopherols (mixed natural concentrate) are a golden... 

The combined effects of the properties of the carotenoids, tocopherols, tocotrienols and the 50% unsaturation of the acids confer on palm oil a higher oxidative stability as compared to a lot of other vegetable oils. 

The effect of tocotrienols on cancer progression was evaluated by Komi-yama and Yamaoka (177). The antitumor activity of tocotrienols was evaluated in terms of the increase in the lifespan of mice inoculated with tumor cells. a-Tocotrienols and y-tocotrienols were effective against the sarcoma cancer cell lines and Ehrlich carcinoma. When human lung carcinomas were challenged with these tocotrienols, a cytotoxic activity due to the tocotrienols was exhibited. Similarly. DMBA-treated rats responded with lower tumor numbers when their diets were supplemented with palm tocotrienols (178). Recently, a-carotene isolated from pahn oil has been shown to have antitumor activity against mouse lung cancer and against skin cancer (179). 

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