THE OXIDATION OF AMINOETHYLCYSTEINE KETIMINE DIMER BY OXYGEN REACTIVESPECIES

The prominent spontaneous reaction of aminoethylcysteine ketimine in t he neutral pH range is the concentration-dependent dimerization (Herma nn, 1961). The carboxylated dimer first produced loses the free carbox yl yielding the more stable decarboxylated dimer (named simply the dim er in this note). In the search for a possible biochemical activity of this uncommon tricyclic compound we have assayed whether it could int eract with oxygen reactive species (H2O2O2-, (OH)-O-.) thus exhibiting a scavenging effect of possible biomedical interest. The dimer intera cts with H2O2 producing compounds detectable by chromatographic proced ures. The presence of Fe2+ stimulates the oxidative reaction by yieldi ng the hydroxyl radical (the Fenton reaction). Using the system xanthi ne oxidase-xanthine as superoxide producer, the dimer oxidation by O-2 (-) has also been documented. Among the oxidation products the presenc e of taurine and cysteic acid has been established. Identification of remaining oxidation products and investigation of the possible functio n of the dimer as a biological scavenger of oxygen reactive species ar e now oncoming.