Tocols

Figure 10.9 Cliromatogi ams of foitified coconut oil obtained by using (a) normal-phase HPLC and (b) GPC/noimal-phase HPLC. Peak identification is as follows 1 (a,b), DL-a-toco-pheryl acetate, 2 (b), 2,6-di-tert-butyl-4-methylphenol 2 (a) and 3 (b), retinyl acetate 3 (a) and 4 (b), tocol 4 (a) and 5 (b), ergocalciferol. Reprinted from Analytical Chemistry, 60, J. M. Brown-Thomas et al., Determination of fat-soluble vitamins in oil matrices by multidimensional liigh-peiformance liquid cliromatography , pp. 1929-1933, copyright 1988, with permission from the American Chemical Society.

Boguth, W. Niemann, H. Electron pin resonance of chromanoxy free radicals from a-, 2-> J3-, y- 8-tocopherol and tocol. Biochim. Biophys. Acta 1971, 248, 121-130. 

Despite the low reproducibility and short life time of the NP columns, they are widely used owing to their better selectivity and resolution power, which enable the separation of (3- and y-isomers easily. The most used stationary phases are silica, aminopropyl- or diol-bonded [476], A more accurate description of the column used can be found in a review about tocol-derivatives analysis by Abidi [477], Kamal-Eldin et al. [478] compare the performance of new silica-type columns, six different silica columns, three amino columns, and one diol column. The new generation column results are much more repeatable and therefore suitable for vitamers analysis. 

E Group active derivatives of tocol and tocotrienol most active is RRR-a-tocoferol = (d)-a-tocoferol Vegetable oils and cereals, vegetables, fruit Depending on the amount of polyunsaturated fatty acids (PUFA) in the diet <1/2 yr 2.9 a-TE 1/2-1 yr 3.6 a-TE 1-19 yr 5.5 up to 13.3 a-TE >19 yr 13 down to 8.3 a-TE pregnancy 0.6 a-TE extra lactating women 2.7 a-TE extra... 

D. R. Carpenter, C. A. McClelland, and L. ]. Romanczyk Jr. Identification and quantitation of gamma-oryzanol components and simultaneous assessment of tocols in rice bran oil. J Amer Chem Soc 1993 70(3) 301-307. 

Tocopherol. Any of a series of structurally similar compounds, methyl-substituted tocols. 

Figure D1.5.1 Structure of tocol 2-methyl-2-(4, 8, 12 -trimethyltridecyl)chroman-6-ol.

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. 

Thirty minutes is sufficient for sample preparation beginning with refined vegetable oils. However, the other sample preparations take up to 120 min because of the incubation, re-extraction, and evaporation steps. Usually, a batch of samples is prepared at the same time to reduce the preparation time per sample. The running time for HPLC analysis is approximately 18 min for normal phase or 14 min for reversed phase in order to quantify all tocols. The running time for normal phase could be cut to 12 min for samples without 5-tocopherol and tocotrienol. 

Constantinides, P.P, Tustian, A., and Kessler, D.R. (2004)Tocol emulsion for drug solubilization and parenteral delivery.Adv. Drug Deliv. Rev., 56 1243-1255. 

These compounds can be divided into two types, tocols and trienols. Although both types have the 6-chromanol ring structure and a phytol-like... 

The levels of cardiovascular factors could also be influenced by the ability of vitamin E to affect activation of arachidonic acid from membrane phospholipids by phospholipase A2. Vitamin E, either given in the diet or by incubation with platelets themselves, was found to inhibit phospholipase A2 in a dose-dependent manner. a-Tocopheryl acetate had little or no effect on the activity of this enzyme, but tocol, without methyl groups in the chroman ring, was more potent than either (+)- or ( )-a-tocopherol, suggesting that the methyl groups were not important for the inhibition but the hydroxy group in the ring was critical for activity [131]. 

Several classes of compounds with antioxidant activity have been identified in oats (Avena sativa L.), including vitamin E tocols, flavonoids, and nonflavonoid phenolic acids (see Handelman et... 

E3. Emmons, C. L., Peterson, D. M., and Paul, G. L., Antioxidant capacity of oat (Avena saliva L.) extracts. 2. In vitro antioxidant activity and contents of phenolic and tocol antioxidants. J. Agric. Food Chem. 47, 4894-4898 (1999). 

S. L. Abidi and T. L. Mounts, Separations of tocopherols and methylated tocols on cyclodextrin-bonded silica, J. Chromatogr., A 664 130 (1994). 

Tocol Isomers Soybean Oil Corn Oil Olive Oil Sunflower Oil Milk Fat (Ghee) Wheat Germ Oil Rice Bran Oil Palm Oil Palm Olein Palm Stearin... 

Stability in plasma is an important requirement for IV emulsions as flocculated droplets may result in lung embolism. It was found that tocol-based emulsions stabilized by sodium deoxycholate/lecithins flocculated strongly when mixed with mouse, rat, and sheep plasma and serum, whereas soya oil-based emulsions with the same emulsifiers did not [123], It was hypothesized that this effect was caused by the adsorption of plasma proteins onto the tocol droplets (opsonization). Indeed, the steric stabilization of emulsions by incorporation of emulsifiers like poloxamer 188 or PEGylated phospholipids such as PEG5000PE proved to be effective in the stabilization of tocol-based emulsions in plasma. Conversely, in vitro studies were... 

Fig. 6.1. HPLC separation of a-tocopherol (peak 1), y-tocopherol (peak 2) and tocol (peak 3). (a) Using hexane and methyl-t-butyl ether (88 12), flow rate 2.0 ml/min, ambient temp., fluorescence detector, Lichrosorb Si60 column, (b) Using hexane and methyl-t-butyl ether (92 8), flowrate 2.0 ml/min, ambient temp., fluorescence detector, Lichrosorb Si60 column, (c) Using hexane and methyl-/-butyl ether (95 5), flowrate 2.0 ml/ min, ambient temp., fluorescence detector, Lichrosorb Si60 column.

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