P-Tocopherol

Fig. 1. The four naturally occutting tocopherols (a-tocopherol, E.E.E. [59-02-9] jall-rac [2074-53-5] (1) p-tocopherol [148-03-8] (2) y-tocopherol [54-28-4] (3) 8-tocopherol [119-13-1] (4)), a-tocotrienol [1721 -51 -3] (5), and p-tocotrienol [14101-61-2] (6) where asterisks denote asymmetric centers and the...

The all-rac forms of P-, y-, and 5-tocopherols can be synthesized using the same condensation reaction as used for i7//-n7iC-a-tocopherol. To synthesize i7//-n7iC-P-tocopherol, 2,5-dimethylhydroquinone instead of trimethyUiydroquinone is condensed with isophytol. For all-rac- - and 5-tocopherol, 2,3-dimethylhydroqiiinone and methyUiydroquinone are used, respectively. 

P-parinaric acid, physical properties, 5 33t P-pentenoic acid, physical properties, 5 3 It P-peroxylactones, 18 484 Beta phase titanium, 24 838 in alloys, 24 854-856 properties of, 24 840, 941 P-phellandrene, 24 493 P-picoline, 21 110 from acrolein, 1 276 uses for, 21 120 P-pinene, 3 230 24 496-497 major products from, 24 478 /-menthol from, 24 522 as natural precursor for aroma chemicals, 3 232 terpenoids from, 24 478-479 P-propiolactone, polymerization of, 14 259 P-quartz solid solution, 12 637—638 Beta ratio, in filtration, 11 329—330 Beta (P) rays, 21 285 P-scission reactions, 14 280-281 P-skytanthine, 2 101 P-spodumene solid solution, 12 638-639 P-sulfur trioxide, 23 756 P-sultones, 23 527 P-tocopherol, 25 793 P-tocotrienol, 25 793 P-vinylacrylic acid, physical properties, 5 33t... 

Wehmeyer et al. (1969) published results on the content of B vitamins (thiamine, riboflavin, and nicotinic acid), vitamin C, and p-carotene and foimd that the morama bean is a good source of both B vitamins and vitamin C, but a poor source of p-carotene. Holse et al. (2010) investigated the content of the eight vitamin E isomers and found that the vitamin E composition in morama beans is dominated by y-tocopherol with 59-234 ng/g, followed by a- and p-tocopherols with 14- 8 gg/g and 1.1-3.3 ng/g, respectively. Eurthermore, traces of 8-tocopherol as well as p- and y-tocotrienols were present in some samples. The remaining two tocotrienols (a- and 8-) were not present in the beans. The presence of a-, p-, and y-tocopherols in the morama bean was also foimd by Mitei et al. (2009) who examined morama oil and by Dubois et al. (1995) who examined two samples of T.fassoglense. 

Figure D1.5.3 Chromatogram of tocopherols and tocotrienols of rice bran oil in normal-phase HPLC (see Basic Protocol). p-Tocopherol was below the level of detection.

Pecan tree (Carya illinoinensis) is native to the United States but has also been naturalized for commercial pecan production throughout the world, including Australia, South Africa, and several middle eastern and South America countries (33). Fat is the predominant constituent in all pecan varieties, ranging from 65% to 75% (w/w) (1, 33, 34). Other constituents include 13.9% carbohydrate, 9.1% protein, 3.5% water, and 1.5% ash (w/w) (1). The predominant fatty acids present in pecan oil are oleic (55%), linoleic (33%), linolenic (2%), palmitic (7%), and stearic (2%) acids (Table 4) (34). The most predominant tocol in pecan oil was y-tocopherol (176mg/kg), followed by ot-tocopherol (lOmg/kg), and then 5- and p-tocopherols (6.2mg/kg) (1). Pecan oil also contains 0.73 g/kg phytosterols that exist primarily as (3-sitosterol (around 90%) (1). 

In 1991 inhibition of PKC activity was found to be at the basis of the vascular smooth muscle cell growth arrest induced by a-tocopherol [16,17]. A number of reports have subsequently confirmed the involvement of PKC in the effect of a-tocopherol on different cell types, including monocytes, macrophages, neutrophils, fibroblasts and mesangial cells [8,18-20]. a-Tocopherol, but not P-tocopherol, was found to inhibit thrombin-induced PKC activation and endothelin secretion in endothelial cells [21]. a-Tocopherol, and not P-tocopherol or trolox, inhibits the activity of PKC fi-om monocytes, followed by inhibition of phosphorylation and translocation of the cytosolic factor p47(phox) and by an impaired assembly of the NADPH-oxidase and of superoxide production [22]. a-Tocopherol has the important biological effect of inhibiting the release of the proinflammatory cytokine, IL-lp, via inhibition of the 5-lipoxygenase pathway [23]. 

Inhibition of PKC by a-tocopherol in vascular smooth muscle cells is observed to occur at concentrations of a-tocopherol close to those measured in healthy adults [24]. P-Tocopherol per se is not very effective but prevents the inhibitory effect of a-tocopherol. The mechanism involved is not related to the radical scavenging properties of these two molecules, which are essentially equal [25]. In vitro studies with recombinant PKC have shown that inhibition by a-tocopherol is not caused by tocopherol-protein interaction, a-Tocopherol does not inhibit PKC expression as well. Inhibition of PKC activity by a-tocopherol occurs at a cellular level by producing dephosphorylation of the enzyme, whereby P-tocopherol is much less potent [26]. Dephosphorylation of PKC occurs via protein phosphatase PP2A, which is activated by the treatment with a-tocopherol [26-28]. 

The following questions remain open. In some cases differential effects of a-tocopherol and P-tocopherol have been found, pointing to a non-antioxidant mechanism at the basis of gene regulation [31,36]. In other cases, however, only a-tocopherol has been tested leaving the mechanism of a-tocopherol action unclarified. Furthermore, the... 

In contrast the mean concentrations of a-tocopherol in vitamin E users increased from 28 pmol/l in 1985 to 29 qmol/l in 1988, 35 pmol/l in 1991, and 56 pmol/l in 1998. Controls not taking any medications had much lower serum concentrations of a-tocopherol (7.5, 9.8,11.8, and 18.3 pg/ml). Concentrations of P-tocopherol, y- tocopherol, and 5-tocopherol in users of vitamin E were lower by up to 50% in users of vitamin E formulations. From these data the authors concluded that there is a considerable risk in the availability of over-the-counter drugs, especially those that can affect the balance between blood clotting and hemorrhage, such as salicylates and a-toco-pherol. Since women over 40 in particular tend to use so-called dietary supplements, in the belief that such products might prevent illness, and because there is unrestricted advertising in the mass media, physicians should obtain a clear medication history from their patients. 

The fact that blood concentrations of P-tocopherol, y-tocopherol, and 5-tocopherol are lowered by a-tocopherol (42) should be taken into account in investigations on the clotting and bleeding balance and in cancer research. 

The predominant form of vitamin E in food is a-tocopherol. This form of the vitamin is also the most biologically potent form (100%), as determined by the rat fertility test. Other forms (and their relative potencies) are P-tocopherol (40%), y-tocopherol (10%), 6-tocopherol (1%), and a-tocotrienol (25%). The rat fertility test is performed as follows. Female rats are fed diets deficient in vitamin E, sufficient in a-tocopherol, or containing a known amount of the test compoimd. The rats are then mated with male rats. The number of living fetuses in the uterus of the female rat is then used to assess the potency of the test compoimd, relative to a-tocopherol. The deficient state results in dead fetuses, spontaneous abortions, and fetal resorptions. 

Synonyms cumotocopherol ( )-3,4-dihydro-2,5,8-trimethyl-2-(4,8,12-trimethyltridecyl)-2H-l-P-benzopyran-6-ol 5,8-dimethyltocol neotocopherol d/-P-tocopherol vitamin E p-xylotocopherol. 

Pyka and Sliwiok separated a-tocopherols, p-tocopherols, y-tocopherols, and 8-tocopherols by normal-phase high-performance liquid chromatography (NP-HPLC) and RP-Cig-HPLC. The selected topological indices based on connectivity (M, x ")> distance matrix W, MTI), and information theory (Zac, Tag) were... 

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