Inhibition of oxidation of aromatic amines in heme-containing hydrogen peroxide systems by substituted 4,6-di-tert-butyl-pyrocatechols.

The substituted pyrocatechols sodium (2,3-dihydroxy-4,6-di-tert-butyl-phenyl)-S-thiosulfate (InH1) and 3-(S-glutathionyl)-4,6-di-tert-butyl-pyrocatechol (InH2) effectively inhibited oxidation of o-phenyle-nediamine and tetramethylbenzidine (TMB) catalyzed by hemin or its complex with BSA (methemalbumin). The method of competitive reactions of aromatic amines (PDA, TMB) and pyrocatechols (InH1, InH2) with active radicals was used for the quantitative determination of rates of radical initiation in systems containing hemin (methemalbumin) and H2O2 (TBHP). The use of the inhibitor method for heme-protein-peroxide systems is complicated by heterogeneity of the radicals generated (HO., RO., HO2., RO2., peroxide-like compounds I and II), formation of complexes of the inhibitors with protein component, and possible interaction of active radicals with organic co-solvents (DMF or DMSO). The system hemin (methemalbumin)-H2O2 (TBHP)-aromatic amines can be used for testing the efficacy of potential bioantioxidants.