Solubility of vitamins

Dubbs, M.D. and Gupta, R.B. Solubility of vitamin E (a-tocopherol) and vitamin K3 (menadione) in ethanol-water mixture. /. 

How structure explains the fat solubility of vitamin A and the water solubility of vitamin C (Section 3.5)... 

Because we could not find in literature the solubilities of 19-Nor-la,25-dihydrovitamin D2 in ethanol and propylene glycol, they were taken equal to the solubility of vitamin D2 in ethanol (Penau and Hagemann, 1946). 

Reversed-phase chromatography is the method of choice for the final step of vitamin K assays. It can easily separate vitamin Ki(20) from lipids with closely related polarities and from structural analogs used as internal standard. Similar to the other fat-soluble vitamins nonaqueous reversed-phased systems are preferable because of the increased solubility of vitamin Ki(20) and co-extracted lipids in the eluents that can be used. 

Method [ll] is the best for obtaining CyS-A inclusion complexes. Equilibrium is attained relatively faster and the solubility of various kinds of drugs could be improved. For example, the solubility of vitamin Ki in water is hardly measurable, but a concentration of 0.2 mg/mL was reached in water containing 7.5x10 M CyS-A (Figure 3). 

Figure 4. Solubility of vitamin D3 in 7.5x10 M cyclosophoraose-A solution at 20 C in methods [l], [H], and [ill] as a function of time.

The measurement of vitamin Be in biological material is complicated by (1) the natural occurrence of vitamin B in six different forms (Fig. 1) (2) the relatively low levels of vitamin B in most biological samples (3) the water solubility of vitamin Be, which excludes the use of organic solvent extraction procedures for purification and enrichment prior to analysis (4) the photosensitivity of vitamin Be, which requires the availability of dark room facilities and (5) the protein binding of PLP. 

Rishi et al. (2011) have reported two different Fl-spectrophotometric methods for a-tocopherol determination in pharmaceuticals and infant milk powder. Method I, was based on the reduction of iron(III) to iron(II) in the presence of vitamin E, and reaction between iron(II) and 1,10-phenanthroline formed iron(II)-o-phenanthroline red complex with maximum wavelength of 510 nm. Method II was based on previously reported work (Prieto et al., 1999) involving the reduction of Mo(VI) to Mo(V) by vitamin E and the subsequent formation of a green phosphate/Mo(V) complex in aqueous sulfuric acid monitored at 695 nm. Triton X-100 was used as a sample carrier for solubility of vitamin E and for removal of the deposits of reaction product on the glass flow-through cell to achieve maximum peak height absorbance. The temperature of reaction coil I was kept at 85 1 C and that of coil II at 20 1°C. 

Figure 6.23 The solubility of vitamins in solutions of sucrose esters of varying alkyl chain length as shown by transmittance data, illustrating maximum solubilization at C q and Ci2. O—O vitamin A alcohol — vitamin D2 — vitamin A acetate. Ratio of vitamin ester water 1 6 200. Drawn from the data of Mima [174].

Table 6.23 shows that the solubility of vitamin A palmitate increases the larger the lyophobic chain and the smaller the polyoxyethylene radical, which is opposite... 

The solubility of vitamin A in surfactant solutions is utilized in an assay procedure for the estimation of naturally occurring vitamin A in chicken livers, synthetic vitamin A in powdered formulations for infants, and vitamin A in stabilized animal-feed supplements [192,193]. The vitamin is solubilized by Triton X-100 and extracted with a mixed solvent. 

The order of elution when using MEKC is vitamin B3 (5.58 min), vitamin Be (6.59 min), vitamin 82 (8.81 min), and vitamin Bi (11.21 min). What conclusions can you make about the solubility of the B vitamins in the sodium dodecylsulfate micelles ... 

Reported cases of vitamin toxicity owing to overdose are usually associated with increased over-the-counter availabiHty of supplemental vitamins and indiscriminate supplementation. The misconception that if a Httle is good a lot is better has compounded toxicological problems with the vitamins. Eat-soluble vitamins tend to accumulate in the body with relatively inactive mechanism for excretion and cause greater toxicological difficulties than do water-soluble vitamins. 

The total antioxidant activity of teas and tea polyphenols in aqueous phase oxidation reactions has been deterrnined using an assay based on oxidation of 2,2 -azinobis-(3-ethylbenzothiazoline-sulfonate) (ABTS) by peroxyl radicals (114—117). Black and green tea extracts (2500 ppm) were found to be 8—12 times more effective antioxidants than a 1-mAf solution of the water-soluble form of vitamin E, Trolox. The most potent antioxidants of the tea flavonoids were found to be epicatechin gallate and epigallocatechin gallate. A 1-mAf solution of these flavanols were found respectively to be 4.9 and 4.8 times more potent than a 1-mAf solution of Trolox in scavenging an ABT radical cation. 

Along with increasing evidence of health benefits from consumption of vitamins at levels much higher than RE) A recommendations comes concern over potential toxicity. This topic has been reviewed (19). Like all chemical substances, a toxic level does exist for each vitarnin. Traditionally it has been assumed that all water-soluble vitamins are safe at any level of intake and all fat-soluble vitamins are toxic, especially at intakes more than 10 times the recommended allowances. These assumptions are now known to be incorrect. Very high doses of some water-soluble vitamins, especially niacin and vitamin B, are associated with adverse effects. In contrast, evidence indicates that some fat-soluble micronutrients, especially vitamin E, are safe at doses many times higher than recommended levels of intake. Chronic intakes above the RDA for vitamins A and D especially are to be avoided, however. 

Salts and Derivatives. Generally the vitamers are high melting crystalline soHds that are very soluble in water and insoluble in most other solvents. Properties of the common forms are Hsted in Table 1. The only commercially important form of vitamin B is pytidoxine hydrochloride (7). This odorless crystalline soHd is composed of colorless platelets melting at 204—206°C (with decomposition). In bulk, it appears white and has a density of - 0.4 kg/L. It is very soluble in water (ca 0.22 kg/L at 20°C), soluble in propylene glycol, slightly soluble in acetone and alcohol (ca 0.014 kg/L), and insoluble in most lipophilic solvents. A 10% water solution shows a pH of 3.2. Both the hydrochloride and corresponding free base sublime without decomposition (16). 

Vitamin rarely occurs in plants. However, Solanumglaucophjllum Solanum malacoyyhn Cestrum diumum and TrinetumJlavescens have been shown to contain water-soluble glycosides of vitamin D analogues with 1 a,25-dihydroxy-vitarnin D activity (16—22). The vitamin D content in various plant and animal materials is shown in Table 3. Vitamin D occurs naturally in all animals (24). 

The solubility (or insolubility) of different vitamins is of concern in nutrition. Molecules of vitamins B and C contain several —OH groups that can form hydrogen bonds with water (Figure 10.3). As a result, they are water-soluble, readily excreted by the body, and must be consumed daily. In contrast, vitamins A, D, E, and K, whose molecules are relatively nonpolar, are water-insoluble. These vitamins are not so readily excreted they tend to stay behind in fatty tissues. This means that the body can draw on its reservoir of vitamins A, D, E, and K to deal with sporadic deficiencies. Conversely, megadoses of these vitamins can lead to very high, possibly toxic, concentrations in the body. 

Molecular structures of vitamin 02 and vitamin B(. Polar groups are shown in color. Vitamin D2 is water-insoluble and vitemin Be is water-soluble. 

Although vitamin K is a fat soluble vitamin, only little stores are found in the body which have to be refilled permanently via dietary input. The role of vitamin K derived from bacteria in the colon is controversely discussed, as the concentration of biliary acids for the resorption the fatsoluble vitamin K is very low in the colon. In addition, only diseases of the small intestine lead to a deficit in vitamin K concentration which cannot be restored by K2 production of colonic bacteria. However, watersoluble vitamin Ks can be resorbed by the colonic mucosa. Maybe because of the little stores for vitamin K, the process of vitamin K-dependent carboxylation of proteins is part of a cycle with several steps during which vitamin K normally is regenerated (see Fig. 1) and thus can be used several times. 

Bile acid sequestrants may interfere with die digestion of fats and prevent die absorption of die fat-soluble vitamins (vitamins A, D, E, and K) and folic acid. When die bile acid sequestrants are used for long-term therapy, vitamins A and D may be given in a water-soluble form or administered parenterally. If bleedingtendencies occur as die result of vitamin K deficiency, parenteral vitamin K is administered for immediate treatment, and oral vitamin K is given for prevention of a deficiency in the futum... 

Photoprotection of Vitamins in Skim Milk by Aqueous Soluble Lycopene - Gum Arabic Microencapsulated. Journal of Agricultural and Food Chemistry, Vol. 55, No. 2, (January 2007), pp. 323-329, ISSN 0021-8561. 

The water-soluble B vitamins supply important components of numerous coenzymes. Many coenzymes contain, in addition, the adenine, ribose, and phosphoryl moieties of AMP or ADP (Figure 7-2). Nicotinamide and riboflavin are components of the redox coenzymes... 

The different solubilities of these two kinds of vitamins have important metabolic consequences. Aqueous body fluids do not dissolve fat-soluble vitamins, so these molecules can be stored in fatty body tissue for a long time. As a result, too much of a fat-soluble vitamin can overload the body s storage capabilities and lead to a toxic reaction. In contrast, the body cannot store water-soluble vitamins instead, it excretes anything more than the amount it can use immediately. People must therefore have a steady supply of water-soluble vitamins in their diets to remain healthy. 

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