The N- and alpha- C-oxidation of N,N-dialkylanilines by rabbit liver microsomes in vitro

Direct trapping of formaldehyde formed via oxidative N-demethylation of N,N-dialkylarylamines by Bacillus megaterium using cysteamine derivatization

Oxidative N-demethylation was measured by incubation experiments using Bacillus megaterium isolated from topsoil as a biocatalyst for the N-demethylation of the N,N-dialkylarylamines N,N-dimethylaniline and N-ethyl-N-methylaniline. Formed formaldehyde, normally difficult to analyse in biological systems because of further metabolization, was successfully trapped and converted into thiazolidine by addition of cysteamine into the incubation media. Studies using N,N-di-(trideutero-methyl)-aniline and N-ethyl-N-(trideuteromethyl)-aniline as well as N,N-di-[methyl-(13)C]-aniline and N-ethyl-N-[methyl-(13)C]-aniline were performed to confirm that the N-demethylation proceeds via formaldehyde.

Sister chromatid exchanges of human peripheral blood lymphocytes induced by N,N-diethylaniline in vitro

N,N-Diethylaniline is a reagent used in organic synthesis and is an important intermediate in the manufacturing of dyes. To evaluate its genotoxicity, we examined whether it can induce sister chromatid exchanges (SCEs) in human lymphocytes. We found that N,N-diethylaniline significantly increased the frequency of SCEs both in the absence and presence of S-9 mix. The SCEs from cultures treated by N,N-diethylaniline in the presence of S-9 mix displayed a marked increase which was about 5-fold greater than the control. ANOVA analyses indicated that there is a dose-response relationship between doses of N,N-diethylaniline and the frequency of SCEs, especially in the presence of S-9 mix. The results suggested that N,N-diethylaniline has genotoxicity.

Effect of various potential inhibitors, activators and inducers on the N-oxidation of isomeric aromatic diazines in vitro using rabbit liver microsomal preparations

1. The effects of various potential inhibitors, activators and inducers on the N-oxidation of isomeric aromatic diazines (pyrazine, pyrimidine and pyridazine) by rabbit liver microsomes have been studied. 2. 2,4-Dichloro-6-phenylphenoxyethylamine (DPEA), SKF 525-A and N-octylamine decreased N-oxide formation at 10(-4) M concentrations. 3. Methimazole and carbon monoxide inhibited the N-oxidation of all three substrates studied. 4. The inhibitory effects were generally exaggerated when hepatic microsomal preparations from phenobarbitone-pretreated animals were used as enzyme source. 5. When phenobarbitone or pyridine were used as inducing agents, the N-oxidation of isomeric aromatic diazines showed considerable induction, whereas beta-naphthoflavone and Arochlor 1254 pretreatment had much weaker effects. 6. It is suggested that P4502E1 and/or 2B are the major subfamilies of P450 involved in the N-oxidation of isomeric diazines.

The metabolism of N-benzyl-4-substituted anilines: factors influencing in vitro C- and N-oxidation

N-Benzyl-4-substituted anilines are metabolized by N-debenzylation, aniline-ring hydroxylation and N-oxidation. Factors affecting metabolism of these secondary anilines have been studied in vitro. Enzymes responsible for C- and N-oxidation are present mainly in the liver, but also occur in lung and kidney and are localized in the endoplasmic reticulum. Quantitative and qualitative species differences were observed in microsomal N-benzylaniline metabolism. In hamsters and mice N-debenzylation is the major route of metabolism. In guinea pig and rabbit, ring hydroxylation is the major pathway whereas the rat uses both pathways to equal extents. The hamster has particularly high N-oxidase activity. A sex difference in microsomal N-benzylaniline metabolism is evident in rats but not mice. Kinetic constants for C- and N-oxidation of N-benzylanilines are reported.

The metabolism of aromatic amines

Aromatic amines are of general interest in drug metabolism and some are a health hazard, particularly as bladder carcinogens. Conditions for the biological ring- and N-oxidation of aniline and its derivatives are reviewed. The metabolism of 2-naphthylamine and aminobiphenyls and the involvement of metabolites of aromatic amines in bladder cancer is discussed.

Microsomal N- and C-oxidation of 4-substituted N-benzylanilines

Using direct specific analytical techniques microsomal metabolism of N-benzyl-4-substituted anilines has been investigated and found to include both N- and C-oxidation. N-Debenzylation was observed with all substrates and species examined. N-Oxidation usually yielded aryl nitrones, although the N-hydroxy derivative of the 4-chloro-substituted substrate was identified in some species. This is the first direct evidence of microsomal N-hydroxylation of a secondary aniline. The metabolic formation of amides from these secondary amines was observed and is believed to be a novel class of metabolite for these substrates.

The in vitro metabolism of N,N-dimethylaniline by guinea pig and rabbit tissue preparations

A study of the in vitro metabolism of N,N-dimethylaniline using guinea pig and rabbit preparations and GLC techniques has confirmed N-demethylation and N-oxidation and established ring hydroxylation as metabolic routes. Whereas N-demethylation and N-oxidation are major routes of metabolism, ring hydroxylation is a comparatively minor pathway. Like N-demethylase and N-oxidase, the 4-hydroxylase has been shown to be a microsomal enzyme. The major ring hydroxylated product of N,N-dimethylaniline is N,N-dimethyl-4-aminophenol; N-methyl-4-aminophenol is subsequently formed. The apparent Km and V max values for N-demethylation, N-oxidation and 4-hydroxylation, are presented for both the guinea pig and the rabbit.