Tocopherol natural

Individual functional groups attached to a partially or fully reduced pyran ring behave much as expected of their aliphatic equivalents but there is often a quantitative difference in their reactivity which enables selective reactions to be carried out on polysubstituted compounds. Many examples of this are known in the tocopherol series which are the most important members of the chroman family. Since they are known by trivial names, these are shown with their structures (674). The most important tocopherol is natural vitamin E or a-tocopherol the four natural tocopherols have 7 -configuration at each of their asymmetric centres at C-2, C-4 and C-8. ... 

The tocotrienols possess one centre of asymmetry, at C-2, in addition to the sites of geometrical isomerism at C-3 and C-7. The equivalent natural tocotrienols to the tocopherols mentioned above have a (IKyi -trans-T-trans configuration [44-47]. Indeed, all natural tocopherols and tocotrienols have the R configuration at C-2 in the ring. 

Supplementation with the antioxidant vitamins ascorbic acid (250 mg) and mixed natural tocopherols (50 IU on alternate days) may be beneficial. Higher doses may vitiate the impact of lipid lowering therapy. Other naturally occurring antioxidants such as resveratrol, 3-catechin, selenium, and various carotenoids found in a variety of fruits and vegetables may provide additional antioxidant defense. Homocysteine, which initiates proatherogenic changes in endothelium, can be reduced in many patients by restriction of total protein intake to the amount required for amino acid replacement. Daily supplementation with up to 2 mg of folic acid plus other B vitamins is also recommended. 

Soybeans and products thereof, except fully refined soybean oil and natural tocopherols, soybean oils derived phytosterols and phytosterol esters, and stand ester... 

The carbons at locations 4 and 8 in the side chains of the tocopherols are asymmetric, as is the number 2 carbon in the chro-man ring. The resulting possible isomers are described as having R or S rotation. The natural tocopherols and tocotrienols are predominantly RRR isomers. Morton (1967) has summarized the chemistry of the tocopherols as shown in Figure 9-7. 

Natural tocopherol mixtures are used as antioxidants, usually at levels up to 500 ppm, along with ascorbyl pahnitate to extend the antioxidant activity. At higher levels (>1000 ppm), a-tocopherol is considered to act as a pro-oxidant. As vegetable oils contain tocols at 200-800 ppm, further additions show only a limited effect. The tocols are very sensitive to oxidation and are more stable in esterified form where the all-important hydroxyl group is not free. However such compounds do not show antioxidant activity until they have been hydrolyzed in vivo to the free phenolic form (11). 

Carbon black treated oil to remove natural tocopherol partially. Antioxidant concentration Is 0.57 mmol/kg. 

Tocopherols are considered as natural antioxidants for lipid-containing foods and marketed as all natural. They are permitted in food application according to GMP regulations (21CFR 182.3890). Natural tocopherols are limited to 0.03% (300 ppm) in animal fats (9 CFR 318.7). As most vegetable oils naturally contain tocopherols, the addition of this antioxidant may pose prooxidant effects. 

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... 

Tocopherol Content. Tocopherols can be determined by colorimetry or GLC (90), or by HPLC (91, 92). Added tocopherols are not permitted in virgin olive oils and crude olive-pomace oils (12). Added ot-tocopherol is allowed in refined olive oil, olive oil, refined olive-pomace oil, and olive-pomace oil to restore natural tocopherol lost during refining with a maximum level of 200 mg/kg of total ot-tocopherol in the final product (12). 

Natural tocopherols and tocotrienols have the 2R, 4 R, 8 R and 2R, h -trans, T-trans configurations, respectively, while synthetic products are racemic mixtures. Natural and synthetic products have similar potentials as antioxidants, but natural products have higher vitamin E activity than synthetic ones. Production capacities of natural and synthetic tocopherols and tocotrienols are enlarging (ANON, 1998). In 1991, the world production of vitamin E compounds was 6800 tons (O Leary, 1993). 

In deep-fat frying, the temperature reaches >170°C, and tocopherols are unstable. The order of stability of different tocopherols remains similar to that at lower temperatures, i.e., a < y < 8 (Gordon and Kourimska, 1995 Lampi and Kamal-Eldin, 1998). However, an opposite order of stability has also been found. During deep-fat frying, the relative stabilities of natural tocopherols and tocotrienols in soybean oil were a-tocopherol > 8-tocopherol > P-tocopherol > y-tocopherol, in corn oil were a-tocopherol > y-tocopherol > 8-tocopherol > y-tocotrienol, and in palm oil were a-tocopherol > S-tocotrienol > a-tocotrienol > y-tocotrienol, respectively (Simonne and Eitenmiller, 1998). The authors assumed that tocotrienols were less stable than tocopherols, because they acted more effectively as antioxidants. 

Natural tocopherols, ascorbic acid and ascorbyl palmitate have universal acceptance. 

The richest sources of vitamin E in the diet are vegetable oils. a-Tocopherol is the major contributor to the total vitamin E activity in some oils, but others contain substantial amounts of y-tocopherol (Figure 6.5). Typically, wheat germ, sunflower, cottonseed, and safflower oils contain about 1700, 500, 400, and 350 mg of a-tocopherol equivalent kg-1, respectively. Tocopherols are concentrated in deodorizer distillate (DOD) during the deodorization step. As a result, DOD is a good source of natural tocopherols that are used to make natural vitamin E. DOD is composed of FAs, mixed mono-, di-, or triacylglycerols, sterols, tocopherols, sterol esters, hydrocarbons, and oxidation by-products. DOD is frequently collected and sold. A... 

St. John s Wort Oil CLR. [Henkel/ Cospha] Vitamin E carrier widt natural tocopherol sin soya oil medium for general skin care and improvement in skin tone. 

S-Tt>capherol, 3,4-Hihydro-2,8 1 i methyl. 2- 4,8,-12-trimethyUridecyl)-2H-l-benzopyran-6-ol 8-methyltocol. C H O, mol wt 402-64. C 80.54%, H 11.52%, O 7.95%. Appears to be a rather common member of the vitamin E complex. Ingredient of Mixed Toeopherols Concentrate, N.F. It was found to constitute approx 30% of the mixed toeopherols in soybean oil. 5% of those in wheat germ oil. and there is evidence of its occurrence in cottonseed and peanut oils. Claimed to be the most potent antioxidant of the toeopherols. It has only one hundredth of the activity of natural -tocopherol in the Evans resorption sterility test for vitamin E. Lsoln from soybean oil Stern et al., J. Am ... 

Figure 12.1 Structure of the eight natural tocopherols. In plant tissues, four tocopherols and four tocotrienols are synthesized, all with a side-chain in the natural RRR configuration (here referred to as a-, p-, y, 6-tocopherol/tocotrienol). The relative concentration of the tocopherols and tocotrienols depends on the plant species and on the plant tissue.

Cells incubated with different natural or synthetic vitamin E analogs show striking differences in cellular responses since most of the synthetic analogs of vitamin E cannot act as antioxidants, and the natural tocopherols have essentially equal antioxidant activity, such differences can only be explained by specific non-... 

Rich in poly-unsaturated fatty acids and natural tocopherols... 

Todd independently isolated /3-tocopherol from w hcat germ oil, showed that on pyrolysis it yielded trimethyl hydroquinone, and independently synthesized a-tocopherol by condensing phytol with trimethyl hydroquinone he synthesized the three dimethyl toeopherols by condensing phytol with the three dimethyl hydroquinones (Bcrgel et al., 19.38). He also synthesized some cjhromans and coumarans by unambiguous methods and showed that they closely resembled the natural tocopherol. 

The well-known series of natural tocopherols consists of methylated tocols derived from phytol. Recently Green ct al. (1959a, 1960) showed the existence of a second, closely related series of natural tocopherols containing an unsaturated (trimethyltrideca-3,7,ll-trienyl) side chain, as represented by e- and fi-tocopherol (Table II). Further chromanols, chromenols, and benzoquinones which may play a role together with or similar to that of vitamin E in the living cell are also listed in Table II. 

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