title: 2,2-Dimethyl-5-t-butyl-1,3-benzodioxole: an unusual inducer of microsomal enzymes.
abstract: Our previous studies have shown that 2,2-dimethyl-5-t-butyl-1,3-benzodioxole (DBBD), a methylenedioxyphenyl (MDP) analog in which the methylene hydrogens have been replaced by methyl groups, does not form an inhibitory complex with cytochrome P-450 nor induce this cytochrome. However, in the present experiments, DBBD-treated male Dub:ICR mice showed an increase in NADPH-dependent cytochrome c (P-450) reductase and epoxide hydrolase activity. This separation of cytochrome P-450 induction from the induction of epoxide hydrolase and NADPH-dependent cytochrome c (P-450) reductase appears to be unique among inducers of xenobiotic metabolizing enzymes. In similar experiments, mice were treated with phenobarbital + DBBD or 3-methylcholanthrene + DBBD and the following parameters were measured: cytochrome P-450 content; NADPH-dependent reduction of cytochrome c; ethylmorphine and benzphetamine N-demethylase; 7-ethoxycoumarin O-deethylase; benzo[a]pyrene hydroxylase; and ethoxyresorufin O-deethylase. The microsomal proteins were examined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE). Phenobarbital + DBBD treatment gave results which did not differ significantly from those obtained with phenobarbital alone. In contrast, cytochrome P-450 content and benzo[a]pyrene hydroxylase and ethoxyresorufin O-deethylase activities were less in mice treated with 3-methylcholanthrene + DBBD than in animals treated with 3-methylcholanthrene alone. SDS-PAGE confirmed that induction of cytochrome P-450 by 3-methylcholanthrene was reduced by DBBD, suggesting that the latter compound may be an antagonist to the Ah cytosolic receptor.
mesh_terms: D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis; D004149:Dioxoles / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D004851:Epoxide Hydrolases / Q000096:biosynthesis; D066298:In Vitro Techniques; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology; D051379:Mice; D008813:Mice, Inbred ICR; D008862:Microsomes, Liver / Q000201:enzymology*; D008970:Molecular Weight; D009251:NADPH-Ferrihemoprotein Reductase / Q000096:biosynthesis; D010634:Phenobarbital / Q000494:pharmacology
chemical_list: D004149:Dioxoles; C037778:2,2-dimethyl-5-tert-butyl-1,3-benzodioxole; D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System; D009251:NADPH-Ferrihemoprotein Reductase; D004851:Epoxide Hydrolases; D010634:Phenobarbital