Derivatives of ascorbic acid

Kaneko, T., Kaji, K. and Matsuo, M. (1993). Protective effect of lipophilic derivatives of ascorbic acid on lipid peroxide-induced endothelial injury. Arch. Biochem. Biophys. 304, 176-180. 

Interest has been shown in using derivatives of ascorbic acid as antioxidants. One such compound is ascorbyl palmitate. In the structure of ascorbyl palmitate, the 2- and 3-positions are occupied by hydroxyl groups the 6-position contains the substituted fatty acid. Other derivatives, synthesized by Seib and associates were ascorbate-2 phosphate and ascorbate 2-triphosphate (27). Both of these compounds were reported to inhibit lipid oxidation in ground meat as measured by chemical means (2). Ascorbate-2-phosphate was also found to inhibit MFD in beef as measured by sensory means (2). The ascorbate-2-triphosphate was not tested as an inhibitor of MFD in this study, but... 

A good route to 2-C-allyl (and hence by reduction, C-alkyl) derivatives of ascorbic acid involves the interaction of L-ascorbic acid with allyl acetates or allyl carbonates in the presence of Pd(0) catalyst.355... 

Ascorbyl palmitate and ascorbyl stearate are synthetic derivatives of ascorbic acid. Ascorbic palmitate is soluble in lipid-containing foods because of its relatively good hydrophobicity (88). Ascorbyl palmitate is hydrolyzed by the digestive system to provide nutritionally available ascorbic acid and palmitic acid, but health claims cannot be made for its vitamin C contribution. 

Ascorbyl palmitate (Figure 6), a synthetic derivative of ascorbic acid, is a white powder with a soapy taste and citms-like odor (34). It has better lipid-solubility compared with that of ascorbic acid and its salts, and is often used in combination with a-tocopherol in lipid-containing foods (11). Ascorbyl palmitate prevents oxidative rancidity by quenching singlet oxygen, among other modes of action (34). 

One problem with the use of the ketal or acetal protecting group for 05,6 protection is the removal of the ketal or acetal without concomitant hydrolysis of the 2-sulfate. Sulfation of free ascorbic acid has been reported to aflFord mixtures or sulfated products (23,26,30). Seib et al. (26) oflEered a rational solution to the problem of regioselective sulfation of ascorbic acid with his observation that the di-anion of ascorbic acid reacts exclusively at the 02 position affording 18 in high yield. The formation of 03 sulfated derivatives of ascorbic acid has not been observed, possibly due to the lability of the 3-0-sulfates to intermolecular hydrolysis or rearrangement to the more stable 18 (2). 

Oxidized Derivatives of Ascorbic Acid Dehydroascorbic Acid... 

Derivatives of ascorbic acid in which either or both of the C5 and C6 positions are in a higher oxidation state have achieved some importance as possible biochemical precursors or catabolites of ascorbic acid in vivo. 

Side-chain oxidized derivatives of ascorbic acid are also implicated in the catabolism of ascorbic acid in plants. Loewus et al. (62) have established the intermediacy of ascorbic acid in the biosynthesis of tartaric acid in the grape. Labeling studies have established a metabolic pathway that must involve C5 and C6 oxidation of ascorbic acid. 

Of the possible side-chain oxidized derivatives of ascorbic acid, all but 5-keto-ascorbic acid and 5-keto-6-formylascorbic acid have been reported. Bakke and Theander (66) formed 6-aldehydoascorbic acid, 37, as an unisolated intermediate in the reductive hydrolysis of 38 to ascorbic acid. Heyns and Linkies (67) synthesized 5-keto-saccharo-ascorbic acid, 40, via the oxidation and subsequent hydrolysis of man-narodilactone, 39. 5-Ketosaccharoascorbic acid appears to exist in solution as its enol tautomer. 

As with previous 5,6-dehydro derivatives of ascorbic acid, configuration about the 5,6-olefin has not been established. 

Cardiovascular Activity of Organotin(IV) Derivatives of Ascorbic Acid and Umbelliferrone... 

Methods of analysing involatile acids [375] and those previously separated on ion-exchange resins [376] were developed by Drawer and co-workers. Much attention has been paid in recent years to the analysis of biological samples. The determination of derivatives of bile acids [377], derivatives of ascorbic acid [378, 379] and of organic acids in biological fluids [380] have been described. Methods of obtaining derivatives of acids and their chromatographic analysis were also described in reviews [381,382]. 

Mercury-containing intermediates have been isolated from the reaction of 6-deoxyhex-5-enopyranose derivatives with mercury salts in aqueous media, which leads to deoxyinososes (Chapter 13), and a C-2-platinum derivative of ascorbic acid is noted in Chapter 16. 

Refersnce to iodo derivatives of ascorbic acid is made in Chapter... 

Wynder. E. L., Kmet, J.. Oungai, N., and Segi, M. An epidemiological investigation of gastric cancer. Cancer, 16 1461-1 6,1963. Yagashita, K., Takahashi, N., Yamamoto, H., Jinnouchi, H., Hiyoshi, S., and Miyakawa, T. Effects of tetraacetyl-bis-dehydroascorbic acid, a derivative of ascorbic acid, on Ehrlich cells and HeLa cells (human carcinoma cells). J. Nutr. Sci. Vitaminol., 22 419-427,1976. 

Natural fats possess a certain degree of resistance to oxidation, owing to the presence of compounds termed antioxidants. These prevent the oxidation of unsaturated fats until they themselves have been transformed into inert products. A number of compounds have this antioxidant property, including phenols, quinones, tocopherols, gallic acid and gallates. In the European Union, propyl, octyl or dodecyl-gallate, butylated hydroxyanisole, butylated hydroxytoluene and ethoxyquin may be added to edible oils as antioxidants in amounts specified in the EC Community Register of Feed Additives 2009. Other substances such as synthetic a-, 7- and 8-tocopherols and various derivatives of ascorbic acid may be used without limit. 

FIGURE 2. Expression of osteoblastic phenotypes in the MC3T3-E1 cells. The MC3T3-E1 cells were split and cultured for the indicated days in either the ascorbic acid-deficient or ascorbic acid-supplemented medium. Ascorbic acid 2-phosphate, a stable derivative of ascorbic acid was used at a final concentration of 0.2 mM. Twenty micrograms of total RNA were analyzed by Northern blotting using radioactive probes of alkaline phosphatase and osteocalcin cDNAs as described in the legend to Fig. 1. P-actin was used as an internal standard. 

Keto derivatives are very rare compounds. Lindberg reported the formation of methyl 3-keto-D-glucopyranoside by chromic acid oxidation of the glucoside (4). 2-0-Methyl-L-a 2/Zo-3-hexulose has been prepared by reduction of a derivative of ascorbic acid 135b). 

A reference to 6-amino-6-deoxy derivatives of ascorbic acid is covered in Chapter 9. 

A macroporous copolymer of styrene and divinylbenzene is suitable as a stationary phase for reversed-phase separations. Bilic (34) used a column with a 5-p.m polystyrene/divinylbenzene copolymer packing for separation of fluorescent derivatives of ascorbic acid and DHA (see Sect. III.F). Recently, Koshi-... 

A derivative of ascorbic acid (vitamin C) and palmitic acid. It is a white or yellowish white powder with a citruslike odor, which is used as an antioxidant for fats and oils and as a source of vitamin C. In amounts of 0.1 to 0.4% by weight of the flour, it serves as an antistaling agent in bakery products. It will retard staling for 2 to 4 days. 

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