Vitamins hydrophilic

Vitamin C is water-soluble (hydrophiLic) vitamin A is fat-soluble (hydrophilic). 

Natural antioxidants may be classified according to their nutritive value or according to their solubility. The hydrophobic vitamin E and the hydrophilic vitamin C are thus important both as nutrients and as antioxidants. The nonnutritive antioxidants may similarly be divided into lipid-soluble and water-soluble antioxidants, as shown in Fig. 16.3, which will also form the basis for a discussion of exploitation of combinations of anhoxidants in order to improve protective effects. 

Chapter 10 is devoted to the preparation and purification of hydrophilic vitamins (C, Bj, Bj, Bg, B[2, nicotinic acid and nicotinamide, pantothenic acid, biotin, and folic acid) in pharmaceutical preparations, food products, and biological samples. 

Watanabe, F. and Miyamoto, E., Hydrophilic vitamins, in Handbook of Thin-Layer Chromatography, Sherma, J. and Fried, B., Eds., Marcel Dekker, New York, 2003, chap. 20. 

How can we keep our health against these reactive oxygen radicals Fortunately, vitamin C (hydrophilic), vitamin E (hydrophobic), flavonoids, and other polyphenols can function as anti-oxidants. These anti-oxidants are phenol derivatives. Phenol is a good hydrogen donor to trap the radical species and inhibits radical chain reactions. The formed phenoxyl radical is actually stabilized by the resonance effect as shown in eq. 1.8. Thus, phenol and polyphenol derivatives are excellent hydrogen donors to inhibit the radical reactions and, therefore, they are called radical inhibitors. 

The benefit of using thin-layer chromatography (TLC) for the identification of unknown vitamins and related compounds by comparing Rf values of the unknown compounds with authentic vitamins is beyond doubt. The quantification of the separated vitamins can be performed by the use of modem densitometry. TLC [or high-performance thin-layer chromatography (HPTLC)], as a powerful separation and analytic tool, is used particularly with pharmaceutical preparations and food products. Because amounts of most hydrophilic vitamins are low, or very low, in tissues or body fluids, bioautography or de-rivatization is used before densitometry. 

In this section, we summarize the recent advance of TLC analysis for hydrophilic vitamins. 

TLC offers great advantages (simplicity, flexibility, speed, and relative low expense) for the separation and analysis of hydrophilic vitamins. 

Several vitamins are known to be photolabile, and the photochemical stability of these compounds is influenced by TPN composition. The photochemical stability depends on composition of the amino acid solutions as well as the presence of lipids in the preparations (i.e., the formation of emulsions). Photochemical decomposition of the hpophihc vitamin A is reduced in admixtures containing lipids, possibly due to diffusion of the vitamin into the lipophilic phase. On the other hand, the hydrophilic vitamin riboflavin is protected by emulsification, probably because the opaque emulsion will reduce the optical transmission of the preparation to some extent (Smith et al., 1988). However, emulsification protects neither the water-soluble vitamin C nor the lipohilic vitamins A and K1 from photochemical degradation, which illustrates the complexity of photochemical reactions in heterogeneous media (Smith et. al., 1988 Billionrey et al., 1993). 

Isol. from baechu kimchi. Stable hydrophilic vitamin C deriv. Skin antioxidant used as a medical additive in commercial cosmetics. [a]o +189.6 (c, 5.0 in H2O). 2-O-P-D-Glucopyranoside Ascorbic acid 2-fl -D-glucoside C12H18O11 338.268 Constit. of the fruit of Lycium barbarum (box thorn). Amorph. cryst. 6-Hexadecanoyl Ascorbyl palndtate, USAN. E304 [137-66-6]... 

Raxofelast (IRFI 016 ( )-5-(acetyloxy)-2,3-dihydro-4,6,7-trimethyl-2-benzofiiranacetic acid) is a new hydrophilic vitamin E-hke antioxidant (Campo et al. 1997). Its activity depends on biotransformation to the deacetylated active metabolite IRFI 005, which has, therefore, been used in vitro in chemical, subcellular and cellular models. 

Ponder, E.L., Fried, B., and Sherma, J., 2004. Thin-layer chromatographic analysis of hydrophilic vitamins in standards and from Helisoma trivolvis snails. Acta Chromatographica. 14 70-81. 

DeLeenheer et al. (1991) contributed a review on the TLC of lipophilic vitamins. They noted that although the 1980s witnessed a proliferation of HPLC methods for the determination of fat-soluble vitamins, the advent of newer HPTLC-densitometric techniques may allow for a resurgence of interest in the 1990s for the analysis of lipophilic vitamins by TLC. Fried (1991) reviewed the literature on the TLC of hydrophilic vitamins from about 1965 to 1988. 

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