Department of Chemistry of Functional Molecule (Imagawa Lab.)

 

J Med Chem (2013) 56, 381-385

Development of Vizantin, a Safe Immunostimulant, based on the Structure-Activity Relationship of Trehalose-6,6’-Dicorynomycolate

Yamamoto, Hirofumi; Oda, Masataka; Nakano, Mayo; Watanabe, Naoyuki; Yabiku, Kenta; Shibutani, Masahiro; Inoue, Masahisa; Imagawa, Hiroshi; Nagahama, Masahiro; Himeno, Seiichiro ; Setsu, Kojun; Sakurai, Jun; Nishizawa, Mugio

 

Bacterial components, including Trehalose 6,6’-dimycolates (TDMs), have attracted considerable attention as lead compounds for adjuvant development. However, these compounds can result in clinical symptoms of septic shock, making it imperative to design suitable ‘safe’ immunostimulants that can activate the immune response without causing toxicity. In this article, we describe the development of Vizantin, 6,6’-bis-O-(3-nonyldodecanoyl)-α,α’-trehalose, on the basis of a structure-activity relationship study (SARs) with trehalose 6,6’-dicorynomycolate (TDCM). Our results show that it was easier to synthesize Vizantin on a large scale. Further it exhibited a more potent prophylactic effect on experimental lung metastasis of B16-F0 melanoma cells and could also stimulate human macrophages, making it a promising candidate as an adjuvant in clinical applications.

 

Department of Microbiology (Nagahama Lab.)

 

Clostridium perfringens Alpha-toxin Recognizes the GM1a-TrkA Complex

 

Masataka Oda, Michiko KaburaTeruhisa TakagishiAyaka SuzueKaori TominagaShiori UranoMasahiro NagahamaKeiko KobayashiKeiko FurukawaKoichi Furukawa and
Jun Sakurai

J Biol Chem (2012) 287, 33070-33079

Clostridium perfringens alpha-toxin is the major virulence factor in the pathogenesis of gas gangrene. Alpha-toxin is a 43-kDa protein with 2 structural domains: the N-domain contains the catalytic site and coordinates the divalent metal ions, and the C-domain is a membrane-binding site. The role of the exposed loop region (72-93 residues) in the N-domain, however, has been unclear. Here, we show that this loop contains a ganglioside-binding motif (H…SxWY…G), which is the same motif seen in botulinum neurotoxin, and directly binds to a specific conformation of the ganglioside GM1a through a carbohydrate moiety. Confocal microscopy analysis using fluorescently labeled BODIPY-GM1a revealed that the toxin colocalized with GM1a and induced clustering of GM1a on the cell membranes. Alpha-toxin was only slightly toxic in b1,4-N-acetylgalactosaminyltransferase knockout mice, which lack the a-series gangliosides that contain GM1a, but was highly toxic in α2,8-sialyltransferase knockout mice, which lack both b-series and c-series gangliosides, similar to the control mice. Moreover, experiments with site-directed mutants indicated that Trp-84 and Tyr-85 in the exposed alpha-toxin loop play an important role in the interaction with GM1a and subsequent activation of TrkA. These results suggest that binding of alpha-toxin to GM1a facilitates the activation of the TrkA receptor and induces a signal transduction cascade that promotes the release of chemokines. Therefore, we conclude that GM1a is the primary cellular receptor for alpha-toxin, which can be a potential target for drug developed against this pathogen.

Laboratory of Molecular Nutrition and Toxicology (Himeno Lab.)

Metallomics (2012) in press HOT Article
The article entitled “Roles of ZIP8, ZIP14, and DMT1 in transport of cadmium and manganese in mouse kidney proximal tubule cells” published in Metallomics, a journal covering the research fields related to biometals, by Dr. Fujishiro et al. was selected as a HOT Article of the issue.

Cadmium (Cd) is known as an environmental toxicant that causes renal damage in animals and humans. Dr. Fujishiro et al. in the Laboratory of Molecular Nutrition and Toxicology have been studying the role of ZIP8, a zinc transporter, in the transport of Cd and Mn. In the above-mentioned paper published in Metallomics, they proposed a hypothesis that ZIP8 plays a significant role in the accumulation of Cd in S3 segment of the proximal tubule cells in the kidney based on the observation on cultured proximal tubule cells and in situ hybridization in mouse kidney.

Department of Physical Chemistry (Fukuyama Lab.)

Heterocycles (2010) 81; 1571-1602.
This review focuses on the structural diversity, biological activities and synthesis of vibsane-type diterpenoids. Vibsane-type diterpenoids are considered to be rarely occurring natural products because they have been found exclusively in a few Viburnum speacies such as V. awabuki, V. odoratissimum, and V. suspensum. These diterpenoids are futher classified into 11-membered ring, 7-membered ring, and reaaranged (neovibsanin) types, and therefore, their chemical diversity forms a unique chemical library. We describe the absolute atereochemistry of the typical 11-membered ring vibsanin B and F, a variety of vibsane-type diterpenoids, the chemical correlations between the three subtypes, their biological activities, and the synthesis of vibsanin F and neovibsanin B.

Department of Biochemistry (Kuzuhara Lab.)

J Biol Chem (2009) 284; 6855-6860
Because the influenza A virus has an RNA genome, its RNA-dependent RNA polymerase, comprising the PA, PB1, and PB2 subunits, is essential for viral transcription and replication. The binding of RNA primers/promoters to the polymerases is an initiation step in viral transcription. In our current study, we reveal the 2.7 A tertiary structure of the C-terminal RNA-binding domain of PB2 by x-ray crystallography. This domain incorporates lysine 627 of PB2, and this residue is associated with the high pathogenicity and host range restriction of influenza A virus. We found from our current analyses that this lysine is located in a unique f-shaped structure consisting of a helix and an encircled loop within the PB2 domain. By electrostatic analysis, we identified a highly basic groove along with this phi loop and found that lysine 627 is located in the phi loop. A PB2 domain mutant in which glutamic acid is substituted at position 627 shows significantly lower RNA binding activity. This is the first report to show a relationship between RNA binding activity and the pathogenicity-determinant lysine 627. Using the Matras program for protein three-dimensional structural comparisons, we further found that the helix bundles in the PB2 domain are similar to that of activator 1, the 40-kDa subunit of DNA replication clamp loader (replication factor C), which is also an RNA-binding protein. This suggests a functional and structural relationship between the RNA-binding mechanisms underlying both influenza A viral transcription and cellular DNA replication. Our present results thus provide important new information for developing novel drugs that target the primer/promoter RNA binding of viral RNA polymerases.

Pharmaceutical Chemistry (Yoshida Lab.)

Staff

  • Prof. Dr. Masahiro Yoshida
  • Dr. Kenji Matsumoto
  • Dr. Tsukasa Hirokane

Research project

Our research is focused on the chemical synthesis of biologically active molecules and the development of new chemical reactions. We have already achieved for the synthesis of various structurally complex natural products utilizing our novel synthetic methods. In the course of our study about the development of new reactions, we established several novel reactions using transition metal catalyst, which enables to lead the eco-friendly new chemical process.

  1. Transition metal-catalyzed organic reactions
  2. Novel methodology for the synthesis of complex heterocyclic molecules
  3. Efficient synthesis of biologically active molecules

Publications

Original articles

  1. Matsumoto, M. Yoshida, M. Shindo
    Heterogeneous Rhodium-Catalyzed Aerobic Oxidative Dehydrogenative Cross-Coupling: Nonsymmetrical Biaryl Amines.
    Angewandte Chemie International Edition, 55, DOI: 10.1002/anie.201600400.
  2. Namba,* K. Takeuchi, Y. Kaihara, M. Oda, A. Nakayama, A. Nakayama, M. Yoshida, K. Tanino*
    Total synthesis of palau’amine
    Nature Communications, 6, 8731 (2015).
  3. Matsumoto, M. Suyama, S. Fujita, T. Moriwaki, Y. Sato, Y. Aso, S. Muroshita, H. Matsuo, K. Monda, K. Okuda, M. Abe, H. Fukunaga, A. Kano, M. Shindo,
    Efficient Total Synthesis of Bongkrekic Acid and Apoptosis Inhibitory Activity of its Analogues
    Chemistry A European Journal 21, 11590-11602 (2015).
  4. Yoshida,* T. Mizuguchi, K. Namba
    One-pot synthesis of tri- and tetrasubstituted pyridines by sequential ring-opening-cyclization-oxidation reaction of N-arylmethyl 3-aziridinylpropiolate esters,
    Angewandte Chemie International Edition, 53, 14550–14554 (2014).
  5. Matsumoto, K. Dougomori, S. Tachikawa, T. Ishii, M. Shindo,
    Aerobic Oxidative Homocoupling of Aryl Amines Using Heterogeneous Rhodium Catalysts
    Organic Letter 16, 4754-4757 (2014).
  6. Yoshida,* T. Nakagawa, K. Kinoshita, K. Shishido,
    Regiocontrolled construction of furo[3,2-c]pyran-4-one derivatives by palladium-catalyzed cyclization of propargylic carbonates with 4-hydroxy-2-pyrones.
    The Journal of Organic Chemistry, 78, 1687–1692 (2013).
  7. Yoshida,* S. Ohno, K. Namba,
    Synthesis of substituted tetrahydrocyclobuta[b]benzofurans by palladium-catalyzed domino substitution-[2+2] cycloaddition of propargylic carbonates with 2-vinylphenols,
    Angewandte Chemie International Edition, 52, 13597–13600 (2013).
  8. Yoshida,* S. Ohno, K. Shishido,
    Synthesis of tetrasubstituted furans by palladium-catalyzed decarboxylative [3+2] cyclization of propargyl b-keto esters.
    Chemistry – A European Journal, 18, 1604–1607 (2012).
  9. Yoshida,* T. Mizuguchi, K. Shishido,
    Synthesis of oxazolidinones by efficient fixation of atmospheric CO2 with propargylic amines using silver/1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) dual catalyst system.
    Chemistry – A European Journal, 18, 15578–15581 (2012).

 

Review articles / Books

  1. Yoshida,
    Synthesis of functionalized cyclic molecules by palladium-catalyzed cyclization of propargylic esters with bis-nucleophiles.
    Heterocycles, 87, 1835–1864 (2013).
  2. Yoshida,
    Development of palladium-catalyzed transformations using propargylic compounds.
    Chem. Pharm. Bull., 60, 285–299 (2012).