N-Nitrosodialkylamine dealkylation in reconstituted systems containing cytochrome P-450 purified from phenobarbitaland β-naphthoflavone-treated rats
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説明
Five cytochrome P-450 forms were purified from livers of rats pretreated with phenobarbital (PB) or beta-naphthoflavone (BNF), and the oxidative dealkylation of N-nitrosodialkylamines by the reconstituted cytochrome P-450 systems was measured. PB-II (P450IIB1) showed very high N-nitrosomethybutylamine (NMBA) debutylase activity, high NMBA demethylase activity and high N-nitrosomethyl-benzylamine (NMBeA) debenzylase activity, suggesting that the increase following PB treatment in hepatic microsomal NMBA debutylation and NMBeA debenzylation was due to the induction of PB-II. BNF-H (P450IA2) showed very high NMBA debutylase and high NMBeA debenzylase activities, and BNF-L (P450IA1) showed NMBA debutylase and high NMBeA debenzylase activities. These results suggested that the increase by BNF pretreatment in hepatic microsomal NMBA debutylation was due mainly to the induction of BNF-H and in some part to that of BNF-L. PB-II also showed very high dealkylation activity of lipophilic N-nitrosodialkylamines with long alkyl moieties. On the other hand, BNF-H dealkylated N-nitrosodipropylamine (NDPA), N-nitrosomethylbutylamine (NMBA) and N-nitrosoethylbutylamine (NEBA) at higher rates than N-nitrosodibutylamine (NDBA). BNF-L dealkylated NEBA at higher rates than NMBeA and NDBA. These results reveal that substrate specificity of each cytochrome P-450 form in N-nitrosodialkylamine metabolism is different from each other and several forms of cytochrome P-450 support each N-nitrosamine dealkylase activity in mammalians.
収録刊行物
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- Archives of Toxicology
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Archives of Toxicology 66 137-142, 1992-02-01
Springer Science and Business Media LLC
