Toxicological Research

Korean Society of Toxicology & Korea Environmental Mutagen Society (한국독성학회)
권호 표지

Effects of Several Inhibitors of Human Liver Microsomal Cytochrome P450 3A4 on Catalytic Activities of the Enzyme

인체 간 조직의 cytochrome P450 3A4의 활성에 대한 몇가지 억제제의 영향

  • 오현숙 (원광대학교 농대 농화학과) ;
  • 이갑상 (원광대학교 농대 농화학과) ;
  • 김복량 (원광대학교 의대 생화학교실)
  • Published : 1995.06.01
Download PDF
⟨ Previous Next ⟩

Abstract

Microsomes from human liver sample HL 110 oxidized aflatoxin $B_1$ $(AFB_1)$ to $AFB_1$ exo-8, 9-epoxide which was detected as a glutathione (GSH) conjugate with excess GSH S-transferase and to aflatoxin $Q_1$ ($AFB_1$; 3$\alpha$-hydroxyafiatoxin $B_1$), and testosterone to 6$\beta$-hydroxytestosterone. Anti-P450 3A4 nearly completely inhibited all of the reactions. Some fiavonoids inhibited all of the reactions. While other fiayonolds stimulated 8, 9-epoxidation and inhibited 3$\alpha$-hydroxylation. Gestodene inhibited all of the reactions when gestodene was metabolized by human liver microsomal P450 3A4 prior to adding substrate. But, ges-todene was added in the enzyme mixtures in the presence of $AFB_1$, it could not inhibit 8, 9-epoxidation of $AFB_1$. Nifedipine and troleandomycin inhibited both of the reactions of $AFB_1$ but only 3$\alpha$-hydroxylation was inhibited by the oxidation product of nifedipine. Although, troleandomycin was known as a mechanism-based inhibitor, the chemical did not show any detectable inhibitory effect on 6$\beta$-hydroxylation of testosterone. The results suggest that there are several different substrate-binding sites on P450 3A4.

Keywords

References

  1. J. Biol. Chem. v.264 Characterization of mRNA species related to human liver cytochrome p-450 nifedipine oxidase and regulation of catalytic lacitivity Bork,R.W.;Muto,T.;Beaune,P.H.;Srivastava,P.K.;Lloyd,R.S.;Guengerich,F.P.
  2. Biochemistry v.29 Catalytic activities of human liver cytochrome p-450 3A4 expressed in Saccharomyces cervisiae Brian,W.R.;Sari,M.A.;Iwasaki,M.;Shimada,T.;Kaminsky,L.S.;Guengerich,F.P.
  3. Biochem. Biophys. Res. Commun. v.82 7,8-Benzoflavone stimulates the metabolic activation of aflatoxin B1 to mutagens by human liver Buening,M.K.;Fortner,J.G.;Kappas,A.;Conney,A.H.
  4. Arch. Biochem. Biophys. v.305 Expression of modified human cytochrome P450 3A4 in Escherichia coli and purification and reconstitution of the enzyme Gillam,E.M.J.;Baba,T.;Kim,B.R.;Ohmori,S.;Guengerich,F.P.
  5. Arch. Biochem. Biophys Expression of cytochrome P450 3A5 in Escherichia coli: Effects of 5' modifications, purification, spectral characterization, reconstitution condition and catalytic activities Gillam,E.M.J.;Guo,Z.;Ueng,Y.F.;Yamazaki,H.;Cock,I.;Reilly,P.E.B.;Hooper,W.D.;Guengerich,F.P.
  6. Chem. Res. Toxicol. v.3 Mechanism-based inactivation of human liver cytochrome P-450 3A4 by gestodene Guengerich,F.P.
  7. 8th Int. conference on cytochrome P450: Biochemistry, Biophysics, and Molecular Biology Mechanism of enhancement and inhibition of cytochrome P450 catalytic activities Guengerich,F.P.;Kim,B.R.;Gillam,E.M.J.;Shimada,T.;Lechner,M.
  8. J. Biol. Chem. v.261 Characterization of rat and human liver microsomal cytochrome P450 forms involved in nifedipine oxidation, a prototype for genetic polymorphism in oxidative drug metabolism Guengerich,F.P.;Martin,M.V.;Beaune,P.H.;Kremers,P.;Wolff,T.;Waxman,D.J.
  9. Arch. Biochem. Biophys. v.312 Expression of modified human cytochrome P450 1A1 in Escherichia coli: effects of 5'substitution, stabilization, purification, spectral characterization and catalytic properties Guo,Z.;Gillam,E.M.J.;Ohmori,S.;Tukey,R.H.;Guengerich,F.P.
  10. Cancer Res. v.54 Metabolism of taxol by human hepatic microsomes and liver slices: participation of cytochrome P450 3A4 and of an unknown P450 enzyme Harris,J.W.;Rahman,A.;Kim,B.R.;Guengerich,F.P.;Collins,J.M.
  11. Biochem. Pharmcol. v.32 Flavonoids, a class of natural products of high pharmacological potency Havsteen,B.
  12. J. Biol. Chem. v.256 Studies on the mechanism of activation of microsomal benzo[α]pyrene hydroxylation by flavonoids Huang,M.T.;Chang,R.L.;Fortner,J.G.;Conney,A.H.
  13. FASEB J. v.7 3α-hydroxylation and 8,9-epoxidation of aflatoxin B1 by cytochrome P450 3A4 : Evidence for allosteric behavior in microsomal membranes and a recombinent enzyme Kim,B.R.;Baba,T.;Gillam,E.M.J.;Guengerich,F.P.
  14. J. Pharmacol. Exp. Ther. v.299 In vitro and in vivo activation of oxidation drug metabolism by flavonoids Lasker,J.M.;Huang,M.T.;Conney,A.H.
  15. DNA and Cell Biol. v.12 The P450 superfamily: Update on new sequences, gene mapping, accession numbers, early trivial names of enzymes, and nomenclature Nelson,D.R.;Kamataki,T.;Waxman,D.J.;Guengerich,F.P.;Estabrook,R.W.;Feyereisen,R.;Gonzalez,F.J.;Coon,M.J.;Gunsalus,I.C.;Gotoh,O.;Okuda,K.;Nebert,D.W.
  16. J. Pharmacol. Exp. Ther. v.224 Inactivation of cytochrome P-450 by a troleandomycin metabolite, Protective role glutathione Pressayre,D.;Tinel,M.;Larrey,D.;Cobert,B.;Funck Brentano,C.;Babany,G.
  17. J. Biol. Chem. v.266 Cytochrome P450: Multipicity of isoforms, substrates, and catalytic and regulation mechanisms Porter,T.D.;Coon,M.J.
  18. Chem. Res. Toxicol. v.5 Oxidation of aflatoxins and sterigmatocystin by human liver microsomes: Significance of aflatoxin Q1 as a detoxification product of aflatoxin B1 Raney,K.D.;Shimada,T.;Kim,D.H.;Groopman,J.D.;Harris,T.M.;Guengerich,F.P.
  19. Mol. Pharmacol. v.27 Variations among untreated rabbits in benzo[a]pyrene metabolism and its modulation by 7,8-benzoflavone Raucy,J.L.;Johnson,E.F.
  20. Chem. Res. Toxicol. Oxidation of aflatoxin B1 by bacterial recombinant human cytochrome P450 enzymes Ueng,Y.F.;Shimada,T.;Yamazaki,H.;Guengerich,F.P.