[Inhibition of peroxidase oxidation of aromatic amines by substituted phenols].
Peroxidase-catalyzed oxidation of o-phenylene diamine (OPD) was competitively inhibited by trimethylhydroquinone (TMHQ), 4-tert-butylpyrocatechol (In5), and 4,6-di-tert-butyl-3-sulfanyl-1,2-dihydroxybenzene (In6). In6 was the most efficient inhibitor (Ki = 11 microM at 20 degrees C in 0.015 M phosphate-citrate buffer, pH 6.0). The effects of In5 and In6 were not preceded by periods of induction of OPD oxidation products (contrary to TMHQ). Peroxidase-catalyzed oxidation of tetramethylbenzidine (TMB) was non-competitively inhibited by In6 and 3-(2-hydroxyethylthio)-4,6-di-tert-butylpyrocatechol (In4), whereas o-aminophenol (OAP) acted as a mixed-type inhibitor. The effects of all three inhibitors were preceded by an induction period, during which TMB oxidation products were formed. Again, In6 was the most efficient inhibitor (Ki = 16 microM at 20 degrees C in 0.015 M phosphate-citrate buffer supplemented with 5% ethanol, pH 6.0). Judging by the characteristics of the inhibitors, taken in aggregate, it is advisable to use the pairs OPD-In5 and OPD-In6 in systems for testing the total antioxidant activity of biological fluids of humans.
Metelitsa
D I
DI
Institute of Bioorganic Chemistry, Belarussian National Academy of Sciences, Minsk, 220141 Belarus. metelitza@iboch.bas-net.by
Naumchik
I V
IV
Karaseva
E I
EI
Polozov
G I
GI
Shadyro
O I
OI
D000588:Amines / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010636:Phenols / Q000737:chemistry
D000588:Amines; D004791:Enzyme Inhibitors; D010636:Phenols; D010544:Peroxidases