Site-specific and bulk-phase generation of hydroxyl radicals in the presence of cupric ions and thiol compounds.

Addition of a thiol compound to a solution containing Cu2+ and H2O2 resulted in the generation of hydroxyl radicals (OH.). These radicals were able to oxidize salicylic acid and tryptamine in a reaction that was strongly inhibited by the OH.-scavenger mannitol. Covalent coupling of the thiol compound to tryptamine did not significantly influence the degradation of the indole moiety subsequent to addition of H2O2 and Cu2+. The inhibiting effect of mannitol, however, was strongly reduced, indicating that the scavenger could not interfere with site-specific reactions of OH..