Hiroshi Yamazaki

Publications (196) View all

• Article: Cytochrome P450 metabolic activities in the small intestine of cynomolgus macaques bred in Cambodia, China, and Indonesia.

  Yasuharu Nakanishi, Hiroyuki Yamashita, Tsuyoshi Yoshikawa, Takeshi Tominaga, Koichiro Nojiri, Yoshiharu Sunaga, Atsunobu Muneoka, Kazuhide Iwasaki, Masahiro Utoh, Chika Nakamura, Hiroshi Yamazaki, Yasuhiro Uno
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  ABSTRACT: Cynomolgus macaques, used in drug metabolism studies due to their evolutionary closeness to humans, are mainly bred in Asian countries, including Cambodia, China, and Indonesia. Cytochromes P450 (P450s) are important drug-metabolizing enzymes, present in liver and small intestine, major drug metabolizing organs. Previously, our investigation did not find statistically significant differences in hepatic P450 metabolic activities measured in cynomolgus macaques bred in Cambodia (MacfaCAM) and China (MacfaCHN). In the present study, P450 metabolic activity was investigated in small intestine of MacfaCAM and MacfaCHN, and cynomolgus macaques bred in Indonesia (MacfaIDN) using P450 substrates, including 7-ethoxyresorufin, bupropion, paclitaxel, diclofenac, S-mephenytoin, bufuralol, chlorzoxazone, and testosterone. The results indicated that P450 metabolic activity of small intestine was not statistically significantly different (< 2.0-fold) in MacfaCAM, MacfaCHN, and MacfaIDN. In addition, statistically significant sex differences were not observed (< 2.0-fold) in any P450 metabolic activity in MacfaCAM as supported by mRNA expression results. These results suggest that P450 metabolic activity of small intestine does not significantly differ statistically among MacfaCAM, MacfaCHN, and MacfaIDN.
  Drug Metabolism and Pharmacokinetics 05/2013; · 2.32 Impact Factor
• Article: Molecular and functional characterization of flavin-containing monooxygenases in cynomolgus macaque.

  Yasuhiro Uno, Makiko Shimizu, Hiroshi Yamazaki
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  ABSTRACT: Flavin-containing monooxygenases (FMOs), drug-metabolizing enzymes essential for the metabolism of endogenous biochemicals and foreign compounds, have been characterized in human (including FMO1-5 and FMO6P), but remain to be investigated in cynomolgus macaque. In this study, cDNAs of cynomolgus FMO1-5 and FMO6 were isolated and characterized. Amino acid sequences of cynomolgus FMO1-5, respectively, shared high sequence identities (94-98%) and were closely clustered in a phylogenetic tree, with human FMO1-5. Eight different transcripts, due to alternative splicing, were isolated for cynomolgus FMO6, which is highly identical (∼96%) to human FMO6P. Among the 10 tissue types analyzed, cynomolgus FMO1, FMO2, FMO4, and FMO6 were most abundantly expressed in kidney, while cynomolgus FMO3 and FMO5 were most abundantly expressed in liver. In kidney and liver, the most abundantly expressed cynomolgus FMO genes were FMO1 and FMO3 respectively. Cynomolgus FMO1, FMO2, FMO3, and FMO5 metabolized benzydamine, and FMO1/FMO3 and FMO3 also metabolized methimazole and trimethylamine, respectively. Rates of benzydamine N-oxygenation (catalyzed by FMO3) varied (approximately 20-fold) among the 28 cynomolgus livers and were significantly correlated with FMO3 protein expression, indicating that the inter-animal variations in benzydamine N-oxygenation might be partly accounted for by the variable FMO3 expression. Cynomolgus FMO6 metabolized benzydamine only slightly, but minimal expression of FMO6 in all tissue precludes the importance of FMO6 in drug metabolism, unlike cynomolgus FMO1, FMO2, FMO3, and FMO5 which were all functional. Abundant expression of FMO1 and FMO3 in kidney and liver, respectively, suggest their importance in drug metabolism in cynomolgus macaque, similar to human.
  Biochemical pharmacology 04/2013; · 4.25 Impact Factor
• Article: Survey of variants of human flavin-containing monooxygenase 3 (FMO3) and their drug oxidation activities.

  Hiroshi Yamazaki, Makiko Shimizu
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  ABSTRACT: Human flavin-containing monooxygenase 3 (FMO3, EC 1.14.13.8) in liver catalyzes a variety of oxygenations of nitrogen- and sulfur-containing medicines and xenobiotic substances. Loss-of-function mutations of the FMO3 gene, the enzyme responsible for trimethylamine N-oxygenation, cause the inherited disorder trimethylaminuria (also known as fish odor syndrome). In this mini-review, mutations of the FMO3 gene reported in the literature and in the National Center for Biotechnology Information single nucleotide polymorphism database were surveyed. Then, the activities of FMO3 variants in human liver microsomes and the activities of recombinantly expressed FMO3 variant proteins with respect to the oxygenation of nitrogen- and sulfur-containing drugs were summarized and the potential for drug interactions was demonstrated. Individual differences in FMO3 function were seen in subjects genotyped for homozygous FMO3 variants. Specific regions of the FMO3 C-terminus are required for functional activity. Naturally truncated FMO3 is believed to have barely detectable function, thereby explaining the relationship with severe impaired phenotypes. The present article provides fundamental, up-to-date information on the importance of human FMO3 in individual xenobiotic oxygenations, including those of new medicines and dietary-derived trimethylamine.
  Biochemical pharmacology 04/2013; · 4.25 Impact Factor
• Article: In Vivo Drug Interactions of the Teratogen Thalidomide with Midazolam: Heterotropic Cooperativity of Human Cytochrome P450 in Humanized TK-NOG Mice.

  Hiroshi Yamazaki, Hiroshi Suemizu, Norie Murayama, Masahiro Utoh, Norio Shibata, Masato Nakamura, F Peter Guengerich
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  ABSTRACT: In vivo drug interactions of the teratogen thalidomide with the model cytochrome P450 (P450) 3A substrate midazolam were investigated in mice with humanized livers. The clearance of midazolam (administered intravenously, 10 mg kg-1) in chimeric mice was enhanced by orally co-administered thalidomide (100 mg kg-1). A larger area under the curve of the major metabolite 1'-hydroxymidazolam (1.7-fold) was obtained with thalidomide because of the heterotropic cooperativity of human P450 3A enzymes. A larger area under the curve of the minor metabolite 4-hydroxymidazolam (3.5-fold) was seen with daily pretreatment with thalidomide for 3 days, presumably because of human P450 3A induction. These results demonstrate that livers of humanized mice mediate drug interactions of thalidomide and suggest interactions of therapeutic agents during therapies with thalidomide.
  Chemical Research in Toxicology 03/2013; · 3.78 Impact Factor
• Article: Binding of Diverse Environmental Chemicals with Human Cytochromes P450 2A13, 2A6, and 1B1 and Enzyme Inhibition.

  Tsutomu Shimada, Donghak Kim, Norie Murayama, Katsuhiro Tanaka, Shigeo Takenaka, Leslie D Nagy, Lindsay M Folkmann, Maryam Foroozesh, Masayuki Komori, Hiroshi Yamazaki, F Peter Guengerich
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  ABSTRACT: A total of 68 chemicals including derivatives of naphthalene, phenanthrene, fluoranthene, pyrene, biphenyl, and flavone were examined for their abilities to interact with human P450s 2A13 and 2A6. Fifty-one of these 68 chemicals induced stronger Type I binding spectra (iron low- to high-spin state shift) with P450 2A13 than those seen with P450 2A6, i.e. the spectral binding intensities (ΔAmax/Ks ratio) determined with these chemicals were always higher for P450 2A13. In addition, benzo[c]phenanthrene, fluoranthene, 2,3-dihydroxy-2,3-dihydrofluoranthene, pyrene, 1-hydroxypyrene, 1-nitropyrene, 1-acetylpyrene, 2-acetylpyrene, 2,5,2',5'-tetrachlorobiphenyl, 7-hydroxyflavone, chrysin, and galangin were found to induce a Type I spectral change only with P450 2A13. Coumarin 7-hydroxylation, catalyzed by P450 2A13, was strongly inhibited by 2'-methoxy-5,7-dihydroxyflavone, 2-ethynylnaphthalene, 2'-methoxyflavone, 2-naphththalene propargyl ether, acenaphthene, acenaphthylene, naphthalene, 1-acetylpyrene, flavanone, chrysin, 3-ethynylphenanthrene, flavone, and 7-hydroxyflavone; these chemicals induced Type I spectral changes with low Ks values. On the basis of the intensities of the spectral changes and inhibition of P450 2A13, we classified the 68 chemicals into eight groups based on the order of affinities for these chemicals and inhibition of P450 2A13. The metabolism of chemicals by P450 2A13 during the assays explained why some of the chemicals that bound well were poor inhibitors of P450 2A13. Finally, we compared the 68 chemicals for their abilities to induce Type I spectral changes of P450 2A13 with the Reverse Type I binding spectra observed with P450 1B1: 45 chemicals interacted with both P450s 2A13 and 1B1, indicating that the two enzymes have some similarty of structural features regarding these chemicals. Molecular docking analyses suggest similarities at the active sites of these P450 enzymes. These results indicate that P450 2A13, as well as Family 1 P450 enzymes, is able to catalyze many detoxication and activation reactions with chemicals of environmental interest.
  Chemical Research in Toxicology 02/2013; · 3.78 Impact Factor