N-ALKYLFORMAMIDES ARE METABOLIZED TO N-ALKYLCARBAMOYLATING SPECIES BY HEPATIC MICROSOMES FROM RODENTS AND HUMANS

被引:23
作者
CROSS, H [1 ]
DAYAL, R [1 ]
HYLAND, R [1 ]
GESCHER, A [1 ]
机构
[1] UNIV ASTON,INST PHARMACEUT SCI,DEPT PHARMACEUT SCI,MECHANISMS DRUG TOX RES GRP,ASTON TRIANGLE,BIRMINGHAM B4 7ET,W MIDLANDS,ENGLAND
关键词
D O I
10.1021/tx00016a014
中图分类号
R914 [药物化学];
学科分类号
100701 ;
摘要
Hepatotoxic formamides such as N-methylformamide (NMF) and N,N-dimethylformamide (DMF) are metabolized in vivo to N-acetyl-S-(N-methylcarbamoyl) cysteine via oxidation at the formyl carbon, which yields a reactive intermediate. The hypothesis was tested that this biotransformation route can be studied in vitro with hepatic fractions. NMF was incubated with microsomes or cytosol obtained from BALB/c mice, and metabolically generated N-methyl-carbamoylating species were analyzed after derivatization with ethanol in base to furnish ethyl N-methylcarbamate. Generation of metabolite was catalyzed by microsomes, but not by cytosol. Detection of the N-methylcarbamoylating species was dependent on the presence in the incubation mixture of NMF, viable microsomes, NADPH, and a thiol-containing agent such as glutathione. Metabolite formation was inhibited by SKF 525-A (3 mM) and abolished when the incubation atmosphere consisted of an air/carbon monoxide mixture (1:1) instead of air. Metabolism was not induced by pretreatment of mice with phenobarbital or β-naphthoflavone. N-Ethylformamide and the DMF metabolite N-(hydroxymethyl)-N-methylformamide, but not DMF, were metabolized by microsomes to the N-alkylcarbamoylating metabolite at a measurable rate. NMF metabolism was also observed with liver microsomes from Sprague-Dawley rats or from humans. In the case of rat microsomes the rate of metabolism was half of that measured with murine microsomes. The results suggest that (i) the metabolic toxification of NMF can be studied in hepatic microsomes and (ii) the oxidation of the formyl moiety in N-alkylformamides is catalyzed by cytochrome P-450. © 1990, American Chemical Society. All rights reserved.
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页码:357 / 362
页数:6
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