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Spontaneous hydrolysis and dehydration of dehydroascorbic acid in aqueous solution
1Department of Medicine, University of Colorado Health Sciences Center and Denver VAH, 4200 East Ninth Avenue, Denver, Colorado, 80262, USA. deutschj@essex.uchsc.edu
Analytical Biochemistry
|July 11, 1998
Summary
Dehydroascorbic acid readily exchanges oxygen atoms with water, incorporating three labeled oxygens. Ascorbic acid, however, exchanges fewer, indicating different water interactions for these vitamin C forms.
Area of Science:
- Biochemistry
- Organic Chemistry
- Analytical Chemistry
Background:
- Ascorbic acid (vitamin C) is a vital antioxidant.
- Dehydroascorbic acid is its oxidized form.
- Understanding their interaction with water is crucial for biochemical processes.
Purpose of the Study:
- To investigate the interaction of dehydroascorbic acid and ascorbic acid with water.
- To determine the sites and extent of oxygen exchange with H218O.
- To elucidate the structural differences in their aqueous behavior.
Main Methods:
- Incubation of dehydroascorbic acid and ascorbic acid in 18O-labeled water.
- Oxidation with hydrogen peroxide or reduction with mercaptoethanol.
- Analysis using gas chromatography-mass spectrometry (GC-MS) of derivatized compounds.
Main Results:
- Dehydroascorbic acid readily incorporated three 18O atoms from labeled water.
- Reduction of 18O-labeled dehydroascorbic acid yielded ascorbic acid with three labeled oxygens.
- Ascorbic acid incubated in labeled water incorporated only two 18O atoms.
- Mass spectrometry analysis localized the extra oxygen to carbon 1 of dehydroascorbic acid.
Conclusions:
- Dehydroascorbic acid undergoes spontaneous hydrolysis and dehydration in aqueous solutions.
- The hydroxyl oxygen from hydrolysis is accepted by carbon 1 in dehydroascorbic acid.
- Ascorbic acid exhibits a significantly lower tendency for hydrolysis compared to dehydroascorbic acid.
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