The reduction of dehydroascorbic acid by human erythrocytes

1. Dehydroascorbic acid (DHA) easily penetrates human erythrocytes. It is rapidly reduced to ascorbic acid by the intact cells or by preparations of erythrocytes haemolysed with water and centrifuged to remove cell debris. The ascorbic acid (AA) produced diffuses slowly from intact cells to the surrounding medium. The reaction continues until practically no DHA remains, the main product apart from AA being dioxogulonic acid (DGA). 2. Ascorbic acid penetrates the erythrocytes very slowly. 3. Neither glutathione (GSH) nor total SH disappears during the reduction of DHA. The reaction is, however, prevented by SH inhibitors. If, as seem probable, SH compounds are involved they must be regenerated very efficiently, possibly through the agency of glutathione reductase. 4. Heated haemolysed erythrocytes reduce DHA at a rate comparable to that occurring in simple solution with similar DHA and GSH concentrations. 5. The findings suggest that an enzyme other than glutathione reductase is involved in the reduction of DHA by human erythrocytes.