Interaction of Ascorbic Acid with Disulfides

Ascorbic Acid, D isulfides, Redox-Potential, ESR Electron spin resonance (EPR) spectra dem onstrate the form ation of a com plex betw een the ascorbate ion and disulfides such as oxidized g lutathione, cystine, gam m a globulin, bovine serum album in, 4-4 ' d ith iopyrid ine, and dithiobutyric acid. However, except in the case o f 4-4 ' dithiopyridine, ascorbic acid (AH2) is not capable o f reducing the disulfide bond in these com pounds. These results can be explained in term s o f the redox potential o f ascorbic acid and its radical sem idehydroascorbic acid (SDA). These com pounds can reduce the S -S bond o f 4-4 ' d ithiopyridine, the redox potential o f which is £o = — 0. IV and, thus, m ore positive than the ones de te r­ m ined for the ascorbic acid system.