Inhibition of Oxidation of Aromatic Amines in Heme-Containing Hydrogen Peroxide Systems by Substituted 4,6-Di-tert-butyl-pyrocatechols

D. I. Metelitza,^1,2 O. B. Rus,¹ A. V. Puchkaev,¹ and O. I. Shadyro³

¹Institute of Bioorganic Chemistry, Academy of Sciences of Belarus, ul. Zhodinskaya 5/2, Minsk, 220141 Belarus; fax: (0172) 63-72-74; E-mail: ibochbel@eco2.iasnet.com

²To whom correspondence should be addressed.

³School of Chemistry, Belorussian State University, ul. Leningradskaya 14, Minsk, 220080 Belarus; fax: (0172) 26-59-42.

Submitted September 12, 1996; revision submitted November 5, 1996.

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-phenylenediamine 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.

KEY WORDS: hemin, methemalbumin, hydrogen peroxide, tert-butyl-hydroperoxide, o-phenylenediamine, tetramethylbenzidine, substituted 4,6-di-tert-butyl-pyrocatechols, bioantioxidants, inhibitors of free radical processes.

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