Water-soluble Vitamins and Related Compounds

L Fotsing, B Boulanger, P Chiap, M Fillet, P Hubert, J Crommen. Multivariate optimization approach for the separation of water-soluble vitamins and related compounds by capillary electrophoresis. Biomed Chromatogr 14 10-11, 2000. 

Water-soluble vitamins in formulations have been determined by use of ion-pair chromatography. The vitamins include several B vitamins as well as niacin, folic acid, and ascorbic acid (565). Vitamins D and Da were rapidly separated on reverse phase columns (247) as are vitamins A, D, and E in multivitamin tablets (564). Addition of silver ions to the mobile phase has been shown to increase the flexibility inherent in RPC by complexing with the unsaturated bonds and thereby decreasing the retention factor. This effect is also observed with other unsaturated drug molecules including steroids (247). Vitamin A and related compounds have... 

Vitamin iJj is a water-soluble vitamin. Cobalatnin is the term used to refer to compounds having vitamin Bj activity, as well as to related compounds. The RDA for vitamin Bu for the adult is 2.0 pg. The vitamin is present in animal products, such as meat, poultry, milk, and fish, but is not present in plant products or in yeast, All of the vitamin B] in our envirorrment originated with synthesis in bacteria, fungi, and algae. 

Milk is a very compKcated dispersed system (see Section 7.6.3.2.1) in which casein molecules form a micellar dispersion, globular whey proteins a colloidal dispersion, fat present in the form of fat droplets (mflk microsomes) forms an emulsion, particles of lipoproteins form a colloidal suspension and low molecular weight substances (lactose and other sugars, amino acids, minerals and water soluble vitamins) form true solutions. Milk s typical white colour is related to the scattering and absorption of light by the fat particles and casein micelles. The yellowish colour that is sometimes seen is caused by carotenoid compounds dissolved in the fat phase (cream and butter), while the greenish colour of whey is caused by riboflavin. 

Vitamins are minor components of foods that play an essential role in human nutrition. Many vitamins are unstable under certain conditions of processing and storage (Table 9-1), and their levels in processed foods, therefore, may be considerably reduced. Synthetic vitamins are used extensively to compensate for these losses and to restore vitamin levels in foods. The vitamins are usually divided into two main groups, the water-soluble and the fat-soluble vitamins. The occurrence of the vitamins in the various food groups is related to their water-or fat-solubility. The relative importance of certain types of foods in supplying some of the important vitamins is shown in Table 9-2. Some vitamins function as part of a coenzyme, without which the enzyme would be ineffective as a biocatalyst. Frequently, such coenzymes are phosphorylated forms of vitamins and play a role in the metabolism of fats, proteins, and carbohydrates. Some vitamins occur in foods as provitamins—compounds that are not vitamins but can be changed by the body into vitamins. Vitamers are members of the same vitamin family. 

Although vitamins have different structures, sources, requirements, and mechanisms of action, they are classified according to their solubility in water or in fats. Vitamins A, D, E, and K are liposoluble, whereas the B-complex (Bi, B2, Bg, B12, niacin, pantothenic acid, biotin, and folic acid) and C vitamins are hydrosoluble. Moreover, there are some organic compounds related to vitamins that are usually classified with the B vitamins and are also hydrosoluble i.e., p-aminobenzoic acid is included among these substances with similarities to vitamins. 

Lipids are bioorganic substances related to fatty acid esters and include a variety of compounds such as glycerol esters, waxes, phosphoglycerides, sphingolipids, natural hydrocarbons, some vitamins, etc. This diversity of compounds is explained by the fact that initially the term lipids was used to describe natural bioorganic substances soluble in hydrocarbons and insoluble in water. Lipids include both small molecules and polymeric materials. Because some simple lipids are not polymeric, their pyrolysis will be discussed only to the extent of being associated with the pyrolysis of complex lipids. However, non-polymeric lipids are commonly associated with polymeric ones, and pyrolytic techniques were frequently applied on the whole lipid without separation for purposes such as classification or identification of microorganisms based on the pyrolysis pattern of their lipids [1]. 

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