Tocopherol tissues

Numerous high pressure Hquid chromatographic techniques have been reported for specific sample forms vegetable oHs (55,56), animal feeds (57,58), seta (59,60), plasma (61,62), foods (63,64), and tissues (63). Some of the methods requite a saponification step to remove fats, to release tocopherols from ceHs, and/or to free tocopherols from their esters. AH requite an extraction step to remove the tocopherols from the sample matrix. The methods include both normal and reverse-phase hplc with either uv absorbance or fluorescence detection. AppHcation of supercritical fluid (qv) chromatography has been reported for analysis of tocopherols in marine oHs (65). 

Following the action of extraordinary stimulants (hypoxic hypoxia, hypoxia + hyperoxia, hypodynamia + hyperthermia), animals demonstrate an accumulation of malonic dialdehyde with a simultaneous fall of antiradical activity of the liver tissue. A preliminary introduction to rats of acetylene amine 3,4,5-tris(morpho-linopropynyl)-l-methylpyrazole 103 and also of tocopherol antioxidant and gutumine antihypoxant averts activation of the lipid peroxidation processes. The inhibition of peroxidation with this agent is mediated by stabilization of ly-zosomal and mitochondrial membranes. Unsaturated amines prevent destruction of the organelle membranes provoked by UV irradiation and incubation at 37°C (pH4.7)(78MIl). 

The term vitamin E describes a family of eight antioxidants, four tocopherols, alpha (a), beta ((3), gamma (y) and delta (8), and four tocotrienols (also a, (3, y, and 8). a-Tocopherol is present in nature in only one form, RRR a-tocopherol. The chemical synthesis of a-tocopherol results in eight different forms (SRR, SSR, SRS, SSS, RSR, RRS, RSS, RRR), only one of which is RRR a-tocopherol. These forms differ in that they can be right (R) or left (S) at three different places in the a-tocopherol molecule. RRR a-tocopherol is the only form of vitamin E that is actively maintained in the human body and is therefore the form of vitamin E found in the largest quantities in the blood and tissue. A protein synthesized in the liver (a-TTP alpha-tocopherol transfer protein) preferentially selects the natural form of vitamin E (RRR a-tocopherol) for distribution to the tissues. However, the mechanisms for the regulation of vitamin E in tissues are not known... 

SU L C, BUI M, KARDINAAL A, GCMEZ-ARACENA J, MARTIN-MORENO J, MARTIN B, THAMM M, SIMONSEN N, van t veer p, kck f, STRAIN s and KOHLMEiER L (1998) Differences between plasma and adipose tissue biomarkers of carotenoids and tocopherols. Cancer Epidemiol Biobarkers Prev 7(11) 1043-8. 

N-Nitrosamine inhibitors Ascorbic acid and its derivatives, andDC-tocopherol have been widely studied as inhibitors of the N-nitrosation reactions in bacon (33,48-51). The effect of sodium ascorbate on NPYR formation is variable, complete inhibition is not achieved, and although results indicate lower levels of NPYR in ascorbate-containing bacon, there are examples of increases (52). Recently, it has been concluded (29) that the essential but probably not the only requirement for a potential anti-N-nitrosamine agent in bacon are its (a) ability to trap NO radicals, (b) lipophilicity, (c) non-steam volatility and (d) heat stability up to 174 C (maximum frying temperature). These appear important requirements since the precursors of NPYR have been associated with bacon adipose tissue (15). Consequently, ascorbyl paImitate has been found to be more effective than sodium ascorbate in reducing N-nitrosamine formation (33), while long chain acetals of ascorbic acid, when used at the 500 and lOOO mg/kg levels have been reported to be capable of reducing the formation of N-nitrosamines in the cooked-out fat by 92 and 97%, respectively (49). 

The importance of vitamin E for maintenance of lipid integrity in vivo is emphasized by the fact that it is the only major lipid-soluble chain-breaking antioxidant found within plasma, red cells and tissue cells. Esterbauer etal. (1991) have shown that the oxidation resistance of LDL increases proportionately with a-tocopherol concentration. In patients with RA, synovial fluid concentrations of a-tocopherol are significantly lower relative to paired serum samples (Fairburn et al., 1992). The low level of vitamin E within the inflamed joint implies it is being consumed via its role in terminating lipid peroxidation and this will be discussed further in Section 3.3. 

Interestingly, the combined supplementation of P-carotene, a-tocopherol, and ascorbic acid has been reported to be protective against 4-(methylnitrosamino)-l-(3-pyridyl)-l-butanone (NNK)-induced lung carcinogenesis in smoke-exposed ferrets through maintaining normal tissue levels... 

Sleet, R.B. and J.H. Soares, Jr. 1979. Some effects of Vitamin E deficiency on hepatic xanthine dehydrogenase activity, lead, and a-tocopherol concentrations in tissues of lead-dosed mallard ducks. Toxicol. Appl. Pharmacol. 47 71-78. 

Lu, J. and G.F. Combs, Jr. 1988b. Excess dietary zinc decreases tissue a-tocopherol in chicks. Jour. Nutr. 118 1349-1359. 

The effect of vitamin E supplementation on a-tocopherol and /(-carotene concentrations in tissues from pasture- and grain-fed cattle was also elucidated with HPLC analysis. The investigation was motivated by the fact that a-tocopherol influences beneficially meat colour and stability [53], and the presence of /(-carotene can modify the amount of a-tocopherol in tissues [54], Samples were extracted with hexane and the concentration of /(-carotene was assessed by HPLC. Some data are listed in Table 2.20. It was concluded from the data that... 

MEAN CONCENTRATION (WITH POOLED S.E.O OF a-TOCOPHEROL AND /1-CAROTENE IN LIVER, FAT AND MUSCLES (jug/g TISSUE) FROM PASTURE- AND GRAIN-FED CATTLE WITH OR WITHOUT VITAMIN E SUPPLEMENT (N = 8)... 

A. Yang, M.J. Brewster, M.C. Lanari and R.K. Tume, Effect of vitamin E supplementation on a-tocopherol and /1-carotene concentrations in tissues from pasture- and grain-fed cattle. Meat Sci. 60 (2002) 35 10. 

Vitamin E, a natural antioxidant, is essential for growth, disease prevention, tissue integrity and reproduction in all fauna. Natural vitamin E, as it occurs in plants, consists mainly of a-tocopherol (III, R = H) with minor amounts of y-tocopherol (IV), although this ratio can vary as for example in the vegetable oil composition shown in Fig. 5a. In animal husbandry, such as dairy farms or cattle feed lots, the stock diets are commonly supplemented with vitamin E, because processed grain-based cereal fodder, hay, and silage are deficient in vitamin This results in higher levels of a-tocopherol... 

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. 

Engelhart, K., Jentzsch, A. M., Eiirst, P., and Biesalski, H. K. (1998). Short-term parenteral application of a-tocopherol leads to increased concentration in plasma and tissues of the rat. Free Rad. Res. 29, 421 26. 

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