Toshiaki Miyake
Keio University
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Publication
Featured researches published by Toshiaki Miyake.
The Journal of Antibiotics | 2005
Masayuki Igarashi; Yoshiaki Takahashi; Tetsuo Shitara; Hikaru Nakamura; Hiroshi Naganawa; Toshiaki Miyake; Yuzuru Akamatsu
Novel antibiotics, active against acid-fast bacteria, caprazamycins, were isolated from the culture broth of Streptomyces sp. MK730-62F2. The planar structures of the compounds were determined by 2D NMR spectroscopic study. Furthermore, the absolute structure of caprazamycin B (2) was established by NMR spectroscopy and X-ray crystallography of its degradation products and by total synthesis of the 5-amino-5-deoxy-D-ribose moiety. In the course of degradation studies of 2 under alkaline and acidic conditions, we obtained the two core components, caprazene (11) and caprazol (14), respectively, in high yield.Structurally, caprazamycins belong to a family of lipo-uridyl antibiotics, which have been discovered as specific inhibitors of a bacterial translocase.
The Journal of Antibiotics | 2013
Yoshiaki Takahashi; Masayuki Igarashi; Toshiaki Miyake; Hiromi Soutome; Kanae Ishikawa; Yasuhiro Komatsuki; Yoshiko Koyama; Naoko Nakagawa; Seiko Hattori; Kunio Inoue; Norio Doi; Yuzuru Akamatsu
Acidic treatment of a mixture of caprazamycins (CPZs) A–G isolated from a screen of novel antimycobacterial agents gave caprazene, a core structure of CPZs, in high yield. Chemical modification of the resulting caprazene was performed to give its various derivatives. The structure–activity relationships of the caprazene derivatives against several mycobacterial species and pathogenic Gram-positive and Gram-negative bacteria were studied. Although caprazene showed no antibacterial activity, the antibacterial activity was restored for its 1′′′-alkylamide, 1′′′-anilide and 1′′′-ester derivatives. Compounds 4b (CPZEN-45), 4d (CPZEN-48), 4f and 4g (CPZEN-51) exhibited more potent activities against Mycobacterium tuberculosis and M. avium complex strains than CPZ-B. These results suggest that caprazene would be a good precursor from which novel semisynthetic antibacterial antibiotics can be designed for the treatment of mycobacterial diseases such as tuberculosis and M. avium complex infection.
Tetrahedron Letters | 2001
Yoshiaki Takahashi; Hitoshi Nakayama; Keiki Katagiri; Kumi Ichikawa; Nobuhiro Ito; Tomohisa Takita; Tomio Takeuchi; Toshiaki Miyake
Abstract Optically pure 1 d - chiro -inositol (DCI) has been synthesized from optically inactive myo -inositol practically in four steps. The crystalline nature of most intermediates and the utilization of inexpensive reagents facilitate the economical mass production of DCI, which is expected to be used in the future for treatment of Type 2 diabetes and polycystic ovary syndrome (PCOS).
Tetrahedron Letters | 1981
Tsutomu Tsuchiya; Toshiaki Miyake; Shunji Kageyama; Sumio Umezawa; Hamao Umezawa; Tomohisa Takita
Abstract 2-0-(α- D -Mannopyranosyl)- L -gulopyranose, the sugar portion of bleomycin has been synthesized.
Carbohydrate Research | 1981
Toshiaki Miyake; Tsutomu Tsuchiya; Yoshiaki Takahashi; Sumio Umezawa
Abstract Methyl 2-deoxy-3- O -sulfonyl-2- p -toluenesulfonamido-α- d -glucopyranoside derivatives were treated with halides in N , N -dimethylformamide. The corresponding 3-halo-α- d -glucopyranosides were formed by a double S N 2 process in high yields via the 3-halo-α- d -allopyranosides, despite the presence of an axial methoxyl group at C-1. The reactions proceeded more readily than the reaction for methyl 4,6- O -cyclohexylidene-2-deoxy-3- O - p -tolylsulfonyl-2- p -toluenesulfonamido-β- d -glucopyranoside. The mechanism for the ready displacement at C-3 in the α- d anomers is discussed. Deoxy compounds were prepared from the corresponding 3-halides by action of tributylstannane, or of sodium in liquid ammonia. Treatment of methyl 4,6- O -cyclohexylidene-2-deoxy-3- O - p -tolylsulfonyl-2- p -toluenesulfonamido-α- d -glucopyranoside with nucleophiles other than halide ions gave the corresponding 2.3-epimino derivative.
Tetrahedron Letters | 1995
Hideaki Ui; Toshiaki Miyake; Hironobu Iinuma; Masaya Imoto; Seiko Hattori; Masa Hamada; Tomio Takeuchi; Sumio Umezawa; Kazuo Umezawa
An inhibitor of phosphatidylinositol-specific phospholipase C, pholipeptin, was purified from the culture broth of Pseudomonas sp. Structural determination by 2D NMR spectroscopy with addition of a small amount of trifluoroacetic acid revealed that it was a novel cyclic lipodepsipeptide (1) consisting of 11 amino acids and a 3-hydroxydecanoic acid moiety.
The Journal of Antibiotics | 2014
Sehei Hirosawa; Yoshiaki Takahashi; Hideki Hashizume; Toshiaki Miyake; Yuzuru Akamatsu
Synthesis and antibacterial activity of tripropeptin C derivatives modified at the carboxyl groups
The Journal of Antibiotics | 2015
Kazushige Sasaki; Yoshihiko Kobayashi; Takashi Kurihara; Yohei Yamashita; Yoshiaki Takahashi; Toshiaki Miyake; Yuzuru Akamatsu
Arbekacin, an aminoglycoside antibiotic, is an important drug because it shows a potent efficacy against methicillin-resistant Staphylococcus aureus. However, resistance to arbekacin, which is caused mainly by the bifunctional aminoglycoside-modifying enzyme, has been observed, becoming a serious problem in medical practice. To create new arbekacin derivatives active against resistant bacteria, we modified the C-4″ and 6″ positions of its 3-aminosugar portion. Regioselective amination of the 6″-position gave 6″-amino-6″-deoxyarbekacin (1), and it was converted to a variety of 6″-N-alkanoyl derivatives (6a−z). Furthermore, regioselective modifications of the 4″-hydroxyl group were performed to give 4″-deoxy-4″-epiaminoarbekacin (2) and its 4″-N-alkanoyl derivatives (12 and 13). Their antibacterial activity against S. aureus, including arbekacin-resistant bacteria, was evaluated. It was observed that 6″-amino-6″-N-[(S)-4-amino-2-hydroxybutyryl]-6″-deoxyarbekacin (6o) showed excellent antibacterial activity, even better than arbekacin.
MedChemComm | 2015
Atsushi Seki; Toshihiro Mori; Kouji Sasaki; Yoshiaki Takahashi; Toshiaki Miyake; Yuzuru Akamatsu
The synthesis of 17-membered azalides was achieved using the following key steps: (i) Beckmann rearrangement of 16-membered oxime derivatives obtained from 3,4′-dideoxymycaminosyltylonolide (DDMT), (ii) amide-selective silane reduction of the corresponding ring-enlarged lactams catalyzed by RhCl3 in the presence of Et3N, and (iii) N-methylation of the resulting secondary amines.
The Journal of Antibiotics | 2018
Yoshiaki Takahashi; Eijiro Umemura; Yoshihiko Kobayashi; Shoichi Murakami; Toru Nawa; Akihiro Morinaka; Toshiaki Miyake; Masakatsu Shibasaki
The emergence and spread of bacteria with resistance to antibacterial drugs in recent years is now considered a significant threat to global public health and the world economy.1, 2 In particular, the severe bacterial infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa have become serious clinical problems because of increased antimicrobial resistance, as observed for vancomycin-resistant S. aureus and multi-drug resistant P. aeruginosa.3 Arbekacin4 (ABK), an aminoglycoside antibiotic, is efficacious against MRSA, and is commonly used to treat infected patients in the clinical setting. This semi-synthetic antibiotic is stable toward AAC(6′)-APH(2″), a bifunctional enzyme present in MRSA, and is also effective against almost all antibiotic-resistant bacteria that produce aminoglycoside-modifying enzymes.5 However, despite its superior antibacterial activity and stability toward aminoglycoside-modifying enzymes, treatment with ABK is limited because of its adverse effect on the kidneys.6, 7 Therefore, we have conducted synthetic studies on a number of ABK derivatives in an effort to decrease the associated toxicity.8, 9