Toshihiko Osawa

Aichi Gakuin University, Nagoya, Aichi, Japan

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Publications (348)847.94 Total impact

  • Takashi Asahi · Yoshimasa Nakamura · Yoji Kato · Toshihiko Osawa
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    ABSTRACT: At the sites of inflammation, hypohalous acids, such as hypochlorous acid and hypobromous acid (HOBr), are produced by myeloperoxidase. These hypohalous acids rapidly react with the primary amino groups to produce haloamines, which are relatively stable and can diffuse long distances and cross the plasma membrane. In this study, we examined the effects of taurine, the most abundant free amino acid in the leukocyte cytosol, on the hypohalous acid-dependent formation of 8-chloro-2'-deoxyguanosine (8-CldG) and 8-bromo-2'-deoxyguanosine (8-BrdG). The reaction of taurine with HOBr yielded taurine bromamine, which is the most stable among other bromamines of α-amino acids. Taurine also enhanced the bromination of only dG among the four 2'-deoxynucleosides, whereas it inhibited the 8-CldG formation. The specificity of taurine for the enhanced formation of halogenated dG is completely different from that of nicotine, an enhancer of chlorination. The amount of dibrominated taurine (taurine dibromamine) closely correlated with the formation of 8-BrdG, suggesting that taurine dibromamine might be a plausible mediator for the dG bromination in vivo.
    No preview · Article · Oct 2015 · Archives of Biochemistry and Biophysics

  • No preview · Article · Oct 2015
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    ABSTRACT: Myeloperoxidase (MPO)-generated halogenating molecules, such as hypochlorous acid and hypobromous acid (HOBr), in inflammatory regions are postulated to contribute to disease progression. In this study, we showed that ergothioneine (EGT), derived from an edible mushroom, inhibited MPO activity as well as the formation of 8-bromo-2'-deoxyguanosine in vitro. The HOBr scavenging effect of EGT is higher than those of ascorbic acid and glutathione. We initially observed that the administration of Coprinus comatus, an edible mushroom containing a high amount of EGT, inhibited the UV-B-induced inflammatory responses and DNA halogenation, suggesting that EGT is a promising anti-inflammatory agent from mushrooms.
    No preview · Article · Sep 2015 · Bioscience Biotechnology and Biochemistry
  • Yuqiu Wu · Kimiko Kazumura · Wakako Maruyama · Toshihiko Osawa · Makoto Naoi
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    ABSTRACT: Rasagiline and selegiline, inhibitors of type B monoamine oxidase (MAO-B), protect neurons from cell death in cellular and animal models. Suppression of mitochondrial membrane permeabilization and subsequent activation of apoptosis cascade, and induction of anti-apoptotic, pro-survival genes are proposed to contribute the anti-apoptotic function. Rasagiline suppresses neurotoxin- and oxidative stress-induced membrane permeabilization in isolated mitochondria, but the mechanism has been not fully clarified. In this paper, regulation of the mitochondrial permeability transition pore by rasagiline and selegiline was examined in apoptosis induced by PK11195, a ligand of the outer membrane translocator protein 18 kDa (TSPO) in SH-SY5Y cells. The pore opening was quantitatively measured using a simultaneous monitoring system for calcium (Ca(2+)) and superoxide (O2 (-)) (Ishibashi et al. in Biochem Biophys Res Commun 344:571-580, 2006). The association of the pore opening with Ca(2+) efflux and ROS increase was proved by the inhibition of Bcl-2 overexpression and cyclosporine A treatment. Potency to release Ca(2+) was correlated with the cytotoxicity of TSPO antagonists, PK11195, FGIN-1-27 and protoporphyrin IX, whereas a TSPO agonist, 4-chloro-diazepamine, did not significantly increase Ca(2+) or cause cell death. Rasagiline and selegiline inhibited mitochondrial Ca(2+) efflux through the mitochondrial permeability transition pore dose dependently. Ca(2+) efflux was confirmed as the initial signal in mitochondrial apoptotic cascade, and the suppression of Ca(2+) efflux may account for the neuroprotective function of rasagiline and selegiline. The quantitative measurement of Ca(2+) efflux can be applied to determine anti-apoptotic activity of neuroprotective compounds. The role of mitochondrial Ca(2+) release in neuronal death and also in neuroprotection by MAO-B inhibitors is discussed.
    No preview · Article · Apr 2015 · Journal of Neural Transmission
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    ABSTRACT: We had isolated an O-desmethylangolensin (O-DMA)-producing bacterium, Clostridium rRNA cluster XIVa strain SY8519. According to chiral separation using HPLC, the SY8519-produced O-DMA exhibited high optical purity. To determine the absolute stereochemistry of O-DMA, we prepared 2-(4-hydroxyphenyl)propionic acid (2-HPPA) from the O-DMA using the Baeyer–Villiger reaction. From chiral analysis of the product, the major peak had the same stereochemistry to that of 2-HPPA produced from genistein by the same bacteria. As we have determined the stereochemistry of SY8519-produced 2-HPPA to have an R configuration, by the chemical synthesis of (S)-2-HPPA, the SY8519-produced O-DMA must also possess R stereochemistry at the 2-position. To study the stereoselective metabolism, we applied racemic dihydrodaidzein to SY8519. The O-DMA was isolated from the culture media and starting material was also recovered. The O-DMA produced was optically active in a similar manner to that produced from daidzein. However, the remaining dihydrodaidzein exhibited no difference between the enantiomers. These results suggested that SY8519 produces (R)-O-DMA from both enantiomers of dihydrodaidzein.
    No preview · Article · Mar 2015 · Food Chemistry
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    ABSTRACT: The formation mechanism for the potent antioxidative o-dihydroxyisoflavones, 8-hydroxydaidzein (8-OHD) and 8-hydroxygenistein (8-OHG), was studied by incubating whole soybeans in a solid culture and a soybean extract in a liquid culture with Aspergillus saitoi. Analyses of changes in the isoflavone analogue content, β-glucosidase activity, and isoflavone hydroxylation ability indicated that 8-OHD and 8-OHG were formed from daidzein and genistein, respectively, by microbial hydroxylation, being respectively liberated from daidzin and genistin by β-glucosidase from A. saitoi during incubation. No selective hydroxylation reaction at the 8-position of daidzein and genistein were apparent during the vegetative stage, but were induced at the stage of sporulation.
    No preview · Article · May 2014 · Bioscience Biotechnology and Biochemistry
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    ABSTRACT: Nervous system controls all the organs in the living like a symphony. In this chapter, the mechanism of neuronal death in aged is discussed in relation to oxidative stress. Polyunsaturated fatty acid (PUFA) is known to be rich in the membranous component of the neurons and plays an important role in maintaining the neuronal functions. Recent reports revealed that oxidation of omega-3 and omega-6 PUFAs, such as docosahexaenoic acid (DHA) and arachidonic acid (ARA), are potent antioxidant but simultaneously, their oxidation products are potentially toxic. In this chapter, the existence of early oxidation products of PUFA is examined in the samples from neurodegenerative disorders and the cellular model. Accumulation of proteins with abnormal conformation is suggested to induce neuronal death by disturbance of proteolysis and mitochondrial function. The role of lipid peroxide and lipid-derived aldehyde adduct proteins is discussed in relation to brain ageing and age-related neurodegeneration.
    No preview · Article · Jan 2014 · Sub-cellular biochemistry
  • Xuebo Liu · Naruomi Yamada · Toshihiko Osawa
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    ABSTRACT: Dopamine is the endogenous neurotransmitter produced by nigral neurons. Dopamine loss can trigger not only prominent secondary morphological changes, but also changes in the density and sensitivity of dopamine receptors; therefore, it is a sign of PD development. The reasons for dopamine loss are attributed to dopamine's molecular instability due to it is a member of catecholamine family, whose catechol structure contributes to high oxidative stress through enzymatic and non-enzymatic oxidation. Oxidative stress in the brain easily leads to the lipid peroxidation reaction due to a high concentration of polyunsaturated fatty acids (PUFA), such as docosahexaenoic acid (DHA, C22:6/ω-3) and arachidonic acid (AA, C18:4/ω-6). Recent studies have shown that lipid hydroperoxides, the primary peroxidative products, could non-specifically react with primary amino groups to form N-acyl-type (amide-linkage) adducts. Therefore, based on the NH2-teminals in dopamine's structure, the aims of this chapter are to describes the possibility that reactive LOOH species derived from DHA/AA lipid peroxidation may modify dopamine to form amide-linkage dopamine adducts, which might be related to etiology of Parkinson's diseases.
    No preview · Article · Jan 2014 · Sub-cellular biochemistry
  • Shinsuke Hisaka · Toshihiko Osawa
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    ABSTRACT: Phospholipids such as phosphatidylethanolamine and phosphatidylcholine play crucial roles in the biological system to maintain the cellular environmental condition. Despite that, oxidative stress targets these phospholipids containing polyunsaturated fatty acids and accompanies the oxidized phospholipids. Recent studies have been suggested that oxidized phospholipids have the relationship with inflammation and might induce the atherosclerosis formation by uptake of oxidized LDL through scavenger receptor as ligands. Red blood cells, which have been studied the bilayer model, are also modified by oxidative stress because hemoglobin can mediate and produce the reactive oxygen species, which leads to lipid peroxidation of biomembrane. In these oxidation processes of biomolecules, hexanoylation against phosphatidylethanolamine and phosphatidylserine, which has the primary amine and is the target of this modification, generates the oxidized membrane such as erythrocyte ghosts. This unique structure of phosphatidylethanolamine and phosphatidylserine is possibly the useful biomarker to evaluate the oxidation of biomembrane in vivo using liquid chromatography tandem mass spectrometry and monoclonal antibody.
    No preview · Article · Jan 2014 · Sub-cellular biochemistry
  • Toshio Niwa · Shin-Ichiro Yokoyama · Toshihiko Osawa
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    ABSTRACT: Soy isoflavonoids have many useful properties. However, they are metabolized in vivo, including in humans. The effect of the metabolism of soy isoflavonoids on their properties is not fully understood. We have isolated the bacterial strain SY8519, which has been shown to metabolize daidzein to O-desmethylangolensin and to produce 2-(4-hydroxyphenyl)propionic acid from genistein. According to chiral HPLC analysis, the 2-(4-hydroxyphenyl)propionic acid obtained from the bacterium was optically active. To determine the absolute stereochemistry of the microbial product, we prepared (S)-2-(4-hydroxyphenyl)propionic acid from (S)-2-phenylpropionic and concluded that the microbial product had an R-configuration by chiral HPLC analysis. We also applied the metabolite to mouse adipocytes and found that 2-HPPA was less effective at reducing leptin secretion than the parent compound genistein. Our results suggested that 'O-desmethylangolensin-production' attenuates the effect of soy isoflavonoids by reducing not only the activity of daidzein but also that of genistein.
    No preview · Article · May 2013 · Food Chemistry
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    ABSTRACT: Maturation and aging induce alterations in glucose and protein metabolism, which are responsible for insulin resistance and sarcopenia. In the present study, we examined the effects of long-term (16 weeks) ingestion of diets supplemented with tetrahydrocurcumin (THC) and/or branched-chain amino acids (BCAAs) on glucose tolerance and soleus muscle protein content in mature rats (28 weeks of age). Intraperitoneal glucose tolerance tests (IPGTTs) were performed at week 6 and week 12 during the experimental period. Glucose tolerance was not affected by 6-week supplementation with THC and/or BCAAs, but was improved by supplementation at 12 weeks. A synergistic effect of THC and BCAAs was not observed. The protein content of the soleus muscle was increased by long-term supplementation with BCAAs, but not THC. These results suggest that THC and BCAAs are potentially beneficial supplements to improving maturation (aging)-related metabolic deterioration.
    No preview · Article · Jan 2013
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    ABSTRACT: N(ε)-(Hexanoyl)lysine, formed by the reaction of lysine with n-6 lipid hydroperoxide, is a lipid peroxidation marker during the initial stage of oxidative stress. The aim of the present study is to indentify N(ε)-(hexanoyl)lysine-modified proteins in neoplastic transformed gastric mucosal cells by N-methyl-N'-nitro-N-nitrosoguanidine, and to compare the levels of these proteins between gastric mucosal cells and normal gastric cells. Much greater fluorescence of 2-[6-(4'-hydroxy)phenoxyl-3H-xanthen-3-on-9-yl]benzoic acid, an index of the intracellular levels of reactive oxygen species, was observed for gastric mucosal cells compared to normal gastric cells. N(ε)-(Hexanoyl)lysine-modified proteins were detected by SDS-PAGE or two-dimensional electrophoresis and Western blotting using anti-N(ε)-(hexanoyl)lysine polyclonal antibody, and a protein band of between 30-40 kDa was clearly increased in gastric mucosal cells compared to normal gastric cells. Two N(ε)-(hexanoyl)lysine-modified protein spots in gastric mucosal cells were identified as the tropomyosin 1 protein by mass spectrometry using a MASCOT search. The existence of N(ε)-(hexanoyl)lysine modification in tropomyosin 1 was confirmed by Western blotting of SDS-PAGE-separated or two-dimensional electrophoresis-separated proteins as well as by the immunoprecipitation with anti-tropomyosin 1 antibody. These data indicate that N(ε)-(hexanoyl)lysine modification of tropomyosin 1 may be related to neoplastic transformation by N-methyl-N'-nitro-N-nitrosoguanidine in gastric epithelial cells.
    Full-text · Article · Jan 2012 · Journal of Clinical Biochemistry and Nutrition
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    ABSTRACT: The O-type forkhead domain transcription factor (FOXO) is involved in many biological processes such as aging, the oxidative stress response, and growth regulation. FOXO activity is tightly controlled within cells. In particular, growth factor signaling pathways and the oxidative stress response can both stimulate nuclear translocation of this transcription factor. Here, we show that tetrahydrocurcumin (THC), a curcumin metabolite, regulates the oxidative stress response and aging via FOXO. In NIH3T3 cells, THC induced nuclear accumulation of FOXO4, a member of the FOXO family of transcription factors, by inhibiting phosphorylation of protein kinase B (PKB)/Akt. In Drosophila melanogaster, THC attenuated the oxidative stress response, an effect that was blocked in a foxo mutant background. THC also extended the life span of Drosophila under normal conditions, and loss of either foxo or Sir2 activity eliminated this effect. Based on these results, THC may regulate the aging process via an evolutionarily conserved signaling pathway that includes both foxo and Sir2.
    Full-text · Article · Dec 2011 · Aging
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    ABSTRACT: Previous studies have shown that activated neutrophils and their myeloperoxidase (MPO)-derived products play a crucial role in the pathogenesis of non-steroidal anti-inflammatory drug (NSAID)-related small intestinal injury. The aim of the present study is to identify dihalogenated proteins in the small intestine on indomethacin administration. Intestinal damage was induced by subcutaneous administration of indomethacin (10 mg/kg) in male Wistar rats, and the severity of the injury was evaluated by measuring the area of visible ulcerative lesions. Tissue-associated MPO activity was measured in the intestinal mucosa as an index of neutrophil infiltration. The dihalogenated proteins were separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) using novel monoclonal antibodies against dibromotyrosine (DiBrY), and they were identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) peptide mass fingerprinting and a Mascot database search. Single administration of indomethacin elicited increased ulcerative area and MPO activity in the small intestine. 2D-PAGE showed an increased level of DiBrY-modified proteins in the indomethacin-induced injured intestinal mucosa and 6 modified proteins were found. Enolase-1 and albumin were found to be DiBrY modified. These proteins may be responsible for the development of neutrophil-associated intestinal injury induced by indomethacin.
    Full-text · Article · Mar 2011 · Journal of Clinical Biochemistry and Nutrition
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    ABSTRACT: We measured the anti-oxidative and anti-inflammatory activities of hot water extracts prepared from 11 species of mushrooms. Anti-oxidative activity was evaluated using the oxygen radical absorbance capacity method, and anti-inflammatory activity was examined by measuring the inhibition of lysine chloramine formation by hypochlorous acid. Hot water extracts of Grifola gargal (G. gargal) showed the strongest anti-oxidative activity and inhibitory effects on lysine chloramines. Hot water extracts of G. gargal were evaluated by HPLC and divided into 8 fractions. The most active fraction among these 8 fractions was further purified by preparative HPLC. The active component isolated by HPLC was identified as ergothioneine (EGT) using spectral analysis. On HPLC analysis, the EGT content in G. gargal was the highest among the 11 species of mushrooms. We also examined the protective role of EGT by examining the inflammatory response of adipocyte cells induced by tumor necrosis factor-α.
    No preview · Article · Mar 2011 · Food Science and Technology Research

  • No preview · Article · Dec 2010 · Free Radical Biology and Medicine
  • Yoji Kato · Toshihiko Osawa
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    ABSTRACT: Research into lipid peroxidation-induced protein modification has been ongoing for many years. Recent studies on lipo-oxidation shows the occurrence of another type of protein modification, amide-type adduct formation by lipid hydroperoxide, as well as classical aldehyde-derived protein modifications. The amide-type modifications can be either classified as alkylamide and carboxyalkylamide according to the formed structures. As an alkylamide-type adduct, Nepsilon-(hexanoyl)lysine can be formed by the reaction of peroxidized n-6 fatty acid with lysine. Nepsilon-(propanoyl)lysine is considered to be generated from oxidation of n-3 fatty acid with lysine. The generation pattern of both might be useful for classification of which fatty acids are more involved in oxidation in vivo. Since the alkylamide type-adducts are relatively stable and detectable from biological specimens like urine, these adducts, especially Nepsilon-(hexanoyl)lysine, are used as reliable markers for not only oxidative stress evaluation but also development of functional food.
    No preview · Article · Sep 2010 · Archives of Biochemistry and Biophysics
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    ABSTRACT: Extracts of Aspergillus spp., Monascus purpureus, Rhizopus microsporus, and Eurotium repens, which are filamentous fungi used in the manufacture of fermented foods including sake, shoyu, miso, shochu, tofuyo, tempeh and katsuobushi, were examined for peroxynitrite scavenging activity. Extracts of Eurotium repens, used in the molding step in the manufacture of katsuobushi, exhibited the highest activity of all the tested extracts. Peroxynitrite scavengers were isolated from Eurotium repens extract and were identified as auroglaucin, dihydroauroglaucin, isodihydroauroglaucin, tetrahydroauroglaucin and flavoglaucin. Tetrahydroauroglaucin exhibited the highest peroxynitrite scavenging activity of the isolated compounds, and showed suppressive effects on the expression of blood adhesion molecules, intercellular adhesion molecule-1 (ICAM-1) and vascular adhesion molecule-1 (VCAM-1), in human umbilical vein endothelial cells (HUVECs) after induction with tumor necrosis factor (TNF-α).
    No preview · Article · Sep 2010 · Food Science and Technology Research
  • Toshio Niwa · Shin-ichiro Yokoyama · Tomomi Ito · Toshihiko Osawa
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    ABSTRACT: Daidzein and genistein are the main aglycones of soy isoflavonoid, and have many useful activities in vitro and in vivo. However, equol, a metabolite of daidzein in vivo, has attracted attention due to its stronger activity than that of the naturally occurring isoflavonoids. We subjected the soy isoflavonoids, including the naturally occurring (S)-equol, to mouse adipocytes, and compared the inhibitory activity on the leptin secretion. Equol, daidzein and genistein inhibited the leptin secretion, whereas O-desmethylangolensin had a lower activity. The inhibitory activity of the isoflavones was not affected by the addition of an iNOS inhibitor and an estrogen.
    No preview · Article · Sep 2010 · Phytochemistry Letters
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    ABSTRACT: The expression of cell adhesion molecules (CAMs) has been implicated as one of the most important causes of the development of inflammatory diseases such as atherosclerosis, and, it is speculated that the prevention of it is an effective approach to the control of atherosclerosis. In the present study, we investigated the effect of sesame lignans on the expression of CAMs in human umbilical vein endothelial cells (HUVECs) induced by tumor necrosis factor-alpha (TNF-alpha). Based on cell-ELISA analysis, we found that sesaminol-6-catechol downregulated the TNF-alpha-induced expression of CAMs in a dose-dependent manner. Moreover, these inhibitory effects were caused to be drastically exerted by downregulating the CAM proteins in TNF-alpha-activated HUVECs at transcriptional level. This suggests, that sesaminol-6-catehcol suppresses the expression of CAMs, and may be an active component of sesame lignans.
    Preview · Article · Aug 2010 · Bioscience Biotechnology and Biochemistry

Publication Stats

16k Citations
847.94 Total Impact Points


  • 2010-2015
    • Aichi Gakuin University
      • • Faculty of Psychological and Physical Science
      • • Department of Nutritional Science
      Nagoya, Aichi, Japan
  • 1979-2015
    • Nagoya University
      • • Department of Applied Molecular Biosciences
      • • Graduate School of Bio-Agricultural Sciences
      • • Department of Biological Science
      Nagoya, Aichi, Japan
  • 2001-2010
    • Sugiyama Jogakuen University
      Nagoya, Aichi, Japan
  • 2008
    • Kyoto Prefectural University of Medicine
      Kioto, Kyoto, Japan
  • 2004
    • Hiroshima Prefectural Technology Research Institute
      Hirosima, Hiroshima, Japan
  • 2002-2003
    • Himeji Institute of Technology
      • School of Humanities for Environmental Policy and Technology
      Nagoya, Aichi, Japan
    • Tokai Gakuen University
      Nagoya, Aichi, Japan
  • 1997-2002
    • Kyoto University
      • • Division of Applied Life Sciences
      • • Department of Pathology and Biology of Diseases
      Kioto, Kyōto, Japan
  • 1999
    • Shizuoka University
      Sizuoka, Shizuoka, Japan
  • 1998
    • Nagasaki University
      Nagasaki, Nagasaki, Japan
    • Aichi University of Education
      • Faculty of Education
      Kariya, Aichi-ken, Japan
  • 1995
    • University of Shizuoka
      • School of Pharmaceutical Sciences
      Sizuoka, Shizuoka, Japan
  • 1991
    • University of California, Davis
      • Department of Environmental Toxicology
      Davis, California, United States
  • 1981
    • Nagoya Women's University
      Nagoya, Aichi, Japan