Spontaneous Conversion ofl-Dehydroascorbic Acid tol-Ascorbic Acid andl-Erythroascorbic Acid

Dehydroascorbic acid, an oxidation product of ascorbic acid (vitamin C), spontaneously decomposed at neutral and higher pH levels to form three products that could be quantitated by HPLC–electrochemical analysis. One of the products was ascorbic acid, suggesting that dehydroascorbic acid was reduced to ascorbic acid without adding an exogenous reductant. The major newly produced compound was almost identical to ascorbic acid by UV spectroscopy, which therefore potentially interfered in the study of ascorbic acid metabolism. The ascorbic acid-like compound was isolated by reversed-phase HPLC and identified asl-erythroascorbic acid by mass spectrometry. Fe(II) and Cu(I) increased, whereas desferrioxamine, a potent iron chelator, inhibitedl-erythroascorbic acid production. Phosphate, used as buffer, and cyanide greatly enhanced dehydroascorbic acid conversion tol-erythroascorbic acid. The identification ofl-erythroascorbic acid and its quantitation by an electrochemical method provides a useful tool for future study of dehydroascorbic acid metabolism.