Inactivation of rat cytochrome P450 2D enzyme by a further metabolite of 4-hydroxypropranolol, the major and active metabolite of propranolol

Shizuo Narimatsu, Takayuki Arai, Yasuhiro Masubuchi, Toshiharu Horie, Masakiyo Hosokawa, Koichi Ueno, Hiroyuki Kataoka, Shigeo Yamamoto, Tsutomu Ishikawa, Arthur K. Cho

Research output: Contribution to journalArticle

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Abstract

Repetitive administration of propranolol (PL) in rats decreases the activities of cytochrome P450 (CYP) 2D enzyme(s) in hepatic microsomes. We examined the properties of 4-hydroxypropranolol (4-OH-PL) as an inactivator of rat liver microsomal CYP2D enzyme(s) using bunitrolol (BTL) 4-hydroxylation and PL 5- and 7-hydroxylations as indices of CYP2D enzyme activity. Rat microsomal BTL 4-hydroxylase activity was inhibited by the addition of 4-OH-PL to the incubation medium. The inhibition was greater after preincubation of microsomes with 4-OH-PL in the presence of NADPH than in its absence. The type of inhibition kinetics of BTL 4-hydroxylase by 4-OH-PL was changed from a competitive type to a noncompetitive type by the preincubation. The inhibition of rat liver microsomal PL 5- and 7-hydroxylases by 4-OH-PL was blocked efficiently by co-incubation with quinine, a typical inhibitor of rat CYP2D enzyme(s), or to a lesser extent by BTL. However, quinidine, a diastereomer of quinine, did not significantly protect against the enzyme inactivation. The protective capacities of the substrate and inhibitors reflected their affinities for rat CYP2D enzyme(s). BTL hydroxylase was not affected by either 1,4-naphthoquinone or 1,4-dihydroxynaphthalene which are possible metabolites of 4-OH-PL. These results provide further evidence to support the notion that PL is biotransformed by rat CYP2D enzyme(s) to 4-OH-PL, which is further oxidized to a chemically reactive metabolite in the active site. The inactivation of CYP is likely the result of covalent binding of the reactive species to an amino acid residue of the active site.

Original languageEnglish
Pages (from-to)988-994
Number of pages7
JournalBiological and Pharmaceutical Bulletin
Volume24
Issue number9
DOIs
Publication statusPublished - 2001

Fingerprint

Propranolol
Cytochrome P-450 Enzyme System
Enzymes
Quinine
Hydroxylation
Microsomes
Mixed Function Oxygenases
Liver
Catalytic Domain
4-hydroxypropranolol
Quinidine
hydroxide ion
NADP
Amino Acids

Keywords

  • 1,4-naphthoquinone
  • 4-hydroxypropranolol
  • Bunitrolol
  • Enzyme inactivation
  • Quinine
  • Rat CYP2D enzyme

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology, Toxicology and Pharmaceutics(all)

Cite this

Inactivation of rat cytochrome P450 2D enzyme by a further metabolite of 4-hydroxypropranolol, the major and active metabolite of propranolol. / Narimatsu, Shizuo; Arai, Takayuki; Masubuchi, Yasuhiro; Horie, Toshiharu; Hosokawa, Masakiyo; Ueno, Koichi; Kataoka, Hiroyuki; Yamamoto, Shigeo; Ishikawa, Tsutomu; Cho, Arthur K.

In: Biological and Pharmaceutical Bulletin, Vol. 24, No. 9, 2001, p. 988-994.

Research output: Contribution to journalArticle

Narimatsu, S, Arai, T, Masubuchi, Y, Horie, T, Hosokawa, M, Ueno, K, Kataoka, H, Yamamoto, S, Ishikawa, T & Cho, AK 2001, 'Inactivation of rat cytochrome P450 2D enzyme by a further metabolite of 4-hydroxypropranolol, the major and active metabolite of propranolol', Biological and Pharmaceutical Bulletin, vol. 24, no. 9, pp. 988-994. https://doi.org/10.1248/bpb.24.988
Narimatsu, Shizuo ; Arai, Takayuki ; Masubuchi, Yasuhiro ; Horie, Toshiharu ; Hosokawa, Masakiyo ; Ueno, Koichi ; Kataoka, Hiroyuki ; Yamamoto, Shigeo ; Ishikawa, Tsutomu ; Cho, Arthur K. / Inactivation of rat cytochrome P450 2D enzyme by a further metabolite of 4-hydroxypropranolol, the major and active metabolite of propranolol. In: Biological and Pharmaceutical Bulletin. 2001 ; Vol. 24, No. 9. pp. 988-994.
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abstract = "Repetitive administration of propranolol (PL) in rats decreases the activities of cytochrome P450 (CYP) 2D enzyme(s) in hepatic microsomes. We examined the properties of 4-hydroxypropranolol (4-OH-PL) as an inactivator of rat liver microsomal CYP2D enzyme(s) using bunitrolol (BTL) 4-hydroxylation and PL 5- and 7-hydroxylations as indices of CYP2D enzyme activity. Rat microsomal BTL 4-hydroxylase activity was inhibited by the addition of 4-OH-PL to the incubation medium. The inhibition was greater after preincubation of microsomes with 4-OH-PL in the presence of NADPH than in its absence. The type of inhibition kinetics of BTL 4-hydroxylase by 4-OH-PL was changed from a competitive type to a noncompetitive type by the preincubation. The inhibition of rat liver microsomal PL 5- and 7-hydroxylases by 4-OH-PL was blocked efficiently by co-incubation with quinine, a typical inhibitor of rat CYP2D enzyme(s), or to a lesser extent by BTL. However, quinidine, a diastereomer of quinine, did not significantly protect against the enzyme inactivation. The protective capacities of the substrate and inhibitors reflected their affinities for rat CYP2D enzyme(s). BTL hydroxylase was not affected by either 1,4-naphthoquinone or 1,4-dihydroxynaphthalene which are possible metabolites of 4-OH-PL. These results provide further evidence to support the notion that PL is biotransformed by rat CYP2D enzyme(s) to 4-OH-PL, which is further oxidized to a chemically reactive metabolite in the active site. The inactivation of CYP is likely the result of covalent binding of the reactive species to an amino acid residue of the active site.",
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AU - Narimatsu, Shizuo

AU - Arai, Takayuki

AU - Masubuchi, Yasuhiro

AU - Horie, Toshiharu

AU - Hosokawa, Masakiyo

AU - Ueno, Koichi

AU - Kataoka, Hiroyuki

AU - Yamamoto, Shigeo

AU - Ishikawa, Tsutomu

AU - Cho, Arthur K.

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AB - Repetitive administration of propranolol (PL) in rats decreases the activities of cytochrome P450 (CYP) 2D enzyme(s) in hepatic microsomes. We examined the properties of 4-hydroxypropranolol (4-OH-PL) as an inactivator of rat liver microsomal CYP2D enzyme(s) using bunitrolol (BTL) 4-hydroxylation and PL 5- and 7-hydroxylations as indices of CYP2D enzyme activity. Rat microsomal BTL 4-hydroxylase activity was inhibited by the addition of 4-OH-PL to the incubation medium. The inhibition was greater after preincubation of microsomes with 4-OH-PL in the presence of NADPH than in its absence. The type of inhibition kinetics of BTL 4-hydroxylase by 4-OH-PL was changed from a competitive type to a noncompetitive type by the preincubation. The inhibition of rat liver microsomal PL 5- and 7-hydroxylases by 4-OH-PL was blocked efficiently by co-incubation with quinine, a typical inhibitor of rat CYP2D enzyme(s), or to a lesser extent by BTL. However, quinidine, a diastereomer of quinine, did not significantly protect against the enzyme inactivation. The protective capacities of the substrate and inhibitors reflected their affinities for rat CYP2D enzyme(s). BTL hydroxylase was not affected by either 1,4-naphthoquinone or 1,4-dihydroxynaphthalene which are possible metabolites of 4-OH-PL. These results provide further evidence to support the notion that PL is biotransformed by rat CYP2D enzyme(s) to 4-OH-PL, which is further oxidized to a chemically reactive metabolite in the active site. The inactivation of CYP is likely the result of covalent binding of the reactive species to an amino acid residue of the active site.

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