Covalent binding of a reactive metabolite derived from propranolol and its active metabolite 4-hydroxypropranolol to hepatic microsomal proteins of the rat

Shizuo Narimatsu, Takayuki Arai, Toshiyuki Watanabe, Yasuhiro Masubuchi, Toshiharu Horie, Tokuji Suzuki, Tsutomu Ishikawa, Michio Tsutsui, Yoshito Kumagai, Arthur K. Cho

Research output: Contribution to journalArticle

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Abstract

Repeated administration of propranolol (PL) to rats causes the inhibition of cytochrome P450-2D (P450-2D) enzyme. We recently found that 4- hydroxypropranolol (4-OH-PL) was biotransformed to 1,4-naphthoquinone (1,4- NQ) by superoxide (SO) anions in medium containing rat liver microsomes and NADPH and proposed that the binding of the quinone to P450-2D apoproteins might be one of mechanisms for the enzyme inhibition [Narimatsu et al. (1995) Chem. Res. Toxicol. 8, 721-728]. In this study, we have searched for possible sources of SO for the conversion of 4-OH-PL to 1,4-NQ in rat liver microsomes and determined the radioactivity covalently bound to microsomal proteins after incubation of radioactive PL and 4-OH-PL with rat liver microsomes. Elimination of 4-OH-PL from a mixture containing microsomes and NADPH was suppressed by carbon monoxide. Antibodies raised to P450-2B1 and -3A2 partially, and antibody against NADPH-cytochrome P450 reductase (fp2) markedly suppressed the reaction. 1,4-NQ was formed concomitantly with 4-OH- PL elimination by a reconstituted preparation of fp2. Binding studies using naphthalene ring (NR)- and side chain (SC)-radiolabeled PL and 4-OH-PL showed that radioactivity covalently bound to microsomal proteins was much higher from 4-OH-PL than from PL for the NR-labeled compounds, but higher from PL than from 4-OH-PL for the SC-labeled compounds. These results suggest that the 4-OH-PL formed from PL by P450-2D enzyme is converted to 1,4-NQ with loss of the side chain, and the 1,4-NQ accounts for most of the radioactivity covalently bound to microsomal proteins, including the P450-2D enzymes. The SO for conversion of 4-OH-PL to 1,4-NQ is supplied mainly by fp2 with some contribution by P450 enzymes.

Original languageEnglish
Pages (from-to)289-295
Number of pages7
JournalChemical Research in Toxicology
Volume10
Issue number3
DOIs
Publication statusPublished - Mar 1997
Externally publishedYes

Fingerprint

Metabolites
Propranolol
Rats
Liver
Proteins
Cytochrome P-450 Enzyme System
Radioactivity
Liver Microsomes
Superoxides
4-hydroxypropranolol
NADP
hydroxide ion
Enzyme inhibition
NADPH-Ferrihemoprotein Reductase
Apoproteins
Antibodies
Carbon Monoxide
Microsomes

ASJC Scopus subject areas

  • Drug Discovery
  • Organic Chemistry
  • Chemistry(all)
  • Toxicology
  • Health, Toxicology and Mutagenesis

Cite this

Covalent binding of a reactive metabolite derived from propranolol and its active metabolite 4-hydroxypropranolol to hepatic microsomal proteins of the rat. / Narimatsu, Shizuo; Arai, Takayuki; Watanabe, Toshiyuki; Masubuchi, Yasuhiro; Horie, Toshiharu; Suzuki, Tokuji; Ishikawa, Tsutomu; Tsutsui, Michio; Kumagai, Yoshito; Cho, Arthur K.

In: Chemical Research in Toxicology, Vol. 10, No. 3, 03.1997, p. 289-295.

Research output: Contribution to journalArticle

Narimatsu, S, Arai, T, Watanabe, T, Masubuchi, Y, Horie, T, Suzuki, T, Ishikawa, T, Tsutsui, M, Kumagai, Y & Cho, AK 1997, 'Covalent binding of a reactive metabolite derived from propranolol and its active metabolite 4-hydroxypropranolol to hepatic microsomal proteins of the rat', Chemical Research in Toxicology, vol. 10, no. 3, pp. 289-295. https://doi.org/10.1021/tx960165e
Narimatsu, Shizuo ; Arai, Takayuki ; Watanabe, Toshiyuki ; Masubuchi, Yasuhiro ; Horie, Toshiharu ; Suzuki, Tokuji ; Ishikawa, Tsutomu ; Tsutsui, Michio ; Kumagai, Yoshito ; Cho, Arthur K. / Covalent binding of a reactive metabolite derived from propranolol and its active metabolite 4-hydroxypropranolol to hepatic microsomal proteins of the rat. In: Chemical Research in Toxicology. 1997 ; Vol. 10, No. 3. pp. 289-295.
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T1 - Covalent binding of a reactive metabolite derived from propranolol and its active metabolite 4-hydroxypropranolol to hepatic microsomal proteins of the rat

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AU - Watanabe, Toshiyuki

AU - Masubuchi, Yasuhiro

AU - Horie, Toshiharu

AU - Suzuki, Tokuji

AU - Ishikawa, Tsutomu

AU - Tsutsui, Michio

AU - Kumagai, Yoshito

AU - Cho, Arthur K.

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N2 - Repeated administration of propranolol (PL) to rats causes the inhibition of cytochrome P450-2D (P450-2D) enzyme. We recently found that 4- hydroxypropranolol (4-OH-PL) was biotransformed to 1,4-naphthoquinone (1,4- NQ) by superoxide (SO) anions in medium containing rat liver microsomes and NADPH and proposed that the binding of the quinone to P450-2D apoproteins might be one of mechanisms for the enzyme inhibition [Narimatsu et al. (1995) Chem. Res. Toxicol. 8, 721-728]. In this study, we have searched for possible sources of SO for the conversion of 4-OH-PL to 1,4-NQ in rat liver microsomes and determined the radioactivity covalently bound to microsomal proteins after incubation of radioactive PL and 4-OH-PL with rat liver microsomes. Elimination of 4-OH-PL from a mixture containing microsomes and NADPH was suppressed by carbon monoxide. Antibodies raised to P450-2B1 and -3A2 partially, and antibody against NADPH-cytochrome P450 reductase (fp2) markedly suppressed the reaction. 1,4-NQ was formed concomitantly with 4-OH- PL elimination by a reconstituted preparation of fp2. Binding studies using naphthalene ring (NR)- and side chain (SC)-radiolabeled PL and 4-OH-PL showed that radioactivity covalently bound to microsomal proteins was much higher from 4-OH-PL than from PL for the NR-labeled compounds, but higher from PL than from 4-OH-PL for the SC-labeled compounds. These results suggest that the 4-OH-PL formed from PL by P450-2D enzyme is converted to 1,4-NQ with loss of the side chain, and the 1,4-NQ accounts for most of the radioactivity covalently bound to microsomal proteins, including the P450-2D enzymes. The SO for conversion of 4-OH-PL to 1,4-NQ is supplied mainly by fp2 with some contribution by P450 enzymes.

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