Dehydroisoascorbic acid

Fruits and vegetables are the most common food sources for vitamin C (15-18). In food, vitamin C exists as two vitamers L-ascorbic acid (AA) and its oxidation product, dehydro-L-ascor-bic acid (DHAA) (Fig. 1) (15,17-19). Total Vitamin C is the sum of the AA and the DHAA contents. A stereoisomer, isoascorbic acid (IAA) is often added to food as an antioxidant. Both LAA and its oxidation product, dehydroisoascorbic acid (DHIAA), can interfere in Total Vitamin C determinations. 

JT Vanderslice, DJ Higgs. Quantitative determination of ascorbic, dehydroascorbic, isoascorbic, and dehydroisoascorbic acids by HPLC in foods and other matrices. J Nutr Biochem 4 184-190, 1993. 

This oxidation, which was developed with ascorbic acid,13 produces D-erythronolactone (4) 14 Hydrogen peroxide is first reduced to water and a hydroxy radical, leading to the formation from 3 of the isoascorbic acid radical 12 The hydroxy radical oxidizes 12 to dehydroisoascorbic acid (13), which in a subsequent step adds hydrogen peroxide. Adduct 14 is than cleaved with base via anion 15 to compound 16. Alkaline hydrolysis of the ester leads to hydroxy acid 17 and the byproduct oxalic acid Subsequent lactonization produces D-erythronolactone (4). 

The fate of D-isoascorbic acid on oxidation has not yet been studied by diffraction methods, but NMR results (29) show that in inert solvents an asymmetric dimer is preferentially formed. In water, however, a mixture of two anomeric pyranose rings results, and the simple, reversible D-isoascorbic acid/dehydroisoascorbic acid equilibrium is lost. This may possibly be one of the factors that reduces the biological activity of D-isoascorbic acid. The latter has an effect that is only 5% of that of vitamin C (30),... 

The structure of dehydroisoascorbic acid isomer (81MI5) in solution is only partially similar to 20. In dimethylformamide (DMF), the preponderant species is a symmetric dimer. In water, signiflcant differences are observed. In fresh aqueous solutions, it is present as bicyclic lactone, but... 

Benzyl l-deoxy-4,5-0-isopropylidene-D- /7//iro-hexo-2,3-diuIo-3,6-furanoside, D-186 Dehydroisoascorbic acid, D-22... 

Patterson, J. W., 1950, The diabetogenic effect of dehydroascorbic acid and dehydroisoascorbic acid, J. Biol. Chem. 183 81-88. 

Kail MA, Andersen C. Improved method for simultaneous determination of ascorbic acid and dehydroascorbic add, isoascorbic acid and dehydroisoascorbic acid in food and biological samples. J Chromatogr B 1999 730 101-11. 

Behrens WA, Madere R. A procedure for the separation and quantitative analysis of ascorbic acid, dehydroascorbic acid, isoascorbic acid, and dehydroisoascorbic acid in food and animal tissue. J Liq Chromatogr 1994 17(11) 2445—55. 

Vanderslice, J. and Higgs, D., Chromatographic separation of ascorbic acid, isoascorbic acid, dehydroascorbic acid and dehydroisoascorbic acid and their quantitation in food products, J. Micronutr. Anal, 4, 109-118, 1988. 

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