Papers - Suenaga, Kiyotake

Isolation and structures of hedaols A, B, and C, new bisnorditerpenes from a Japanese brown alga

Takada Noboru, Watanabe Reiko, Suenaga Kiyotake, Yamada Kaoru, Uemura Daisuke

Journal of Natural Products 64 ( 5 ) 653 - 655 2001.05

Accepted,  ISSN  0163-3864

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<p>New bisnorditerpenes, hedaols A (1), B (2), and C (3), were isolated from the Japanese brown alga Sargassum sp. Their structures were determined by spectroscopic analysis. The absolute stereocenter of 1 was determined by the modified Mosher's method. Hedaols showed low cytotoxicity against P388 cells.</p>

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Isolation and structures of haterumadioxins A and B, cytotoxic endoperoxides from the Okinawan sponge Plakortis lita

Takada N., Watanabe M., Yamada A., Suenaga K., Yamada K., Ueda K., Uemura D.

Journal of Natural Products 64 ( 3 ) 356 - 359 2001.03

Accepted,  ISSN  0163-3864

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<p>Cytotoxic endoperoxides, haterumadioxins A (1) and B (2), were isolated from the Okinawan sponge Plakortis lita. Their structures were determined by spectroscopic analysis. The absolute stereostructure of 1 was determined by degradation reactions and the modified Mosher's method. Haterumadioxins showed significant cytotoxicity against 38 human cancer cell lines.</p>

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Enantioselective synthesis of attenols A and B

Suenaga Kiyotake, Araki Keisuke, Sengoku Tetsuya, Uemura Daisuke

Organic Letters 3 ( 4 ) 527 - 529 2001.02

Accepted,  ISSN  1523-7060

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<p>(Matrix presented) Enantioselective synthesis of attenols A and B was accomplished by using diastereoselective hydroboration, Lindlar reduction, and acid-catalyzed acetal formation.</p>

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Haterumaimides A-E, five new dichlorolissoclimide-type diterpenoids from an ascidian, Lissoclinum sp.

Uddin Md Jasim, Kokubo Susumu, Suenaga Kiyotake, Ueda Katsuhiro, Uemura Daisuke

Heterocycles 54 ( 2 ) 1039 - 1047 2001.02

Accepted,  ISSN  0385-5414

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<p>Five new dichlorolissoclimide-type diterpenoids, haterumaimides A-E, were isolated from an ascidian, Lissoclinum sp., and the absolute stereostructures of haterumaimides A-D and the relative stereostructure of haterumaimide E were determined by spectroscopic and chemical analyses. Haterumaimides A-E inhibited the first cleavage of fertilized sea urchin eggs and exhibited cytotoxicity against P388 cells.</p>

Kohamaic acids A and B, novel cytotoxic sesterterpenic acids, from the marine sponge Ircinia sp

Kokubo Susumu, Yogi Kentaro, Uddin Md Jasim, Inuzuka Toshiyasu, Suenaga Kiyotake, Ueda Katsuhiro, Uemura Daisuke

Chemistry Letters  ( 2 ) 176 - 177 2001.02

Accepted,  ISSN  0366-7022

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<p>Two new sesterterpenic acids, which exhibited moderate cytotoxicity, were isolated from the marine sponge Ircinia sp. Their absolute stereochemistries were determined by spectroscopic and chemical analyses. Their configurations at C15 were different from those of previously isolated sesterterpenes. This result suggests the existence of a (14Z)-geranylfarnesyl pyrophosphate, which is yet unknown in nature.</p>

Structures of amamistatins A and B, novel growth inhibitors of human tumor cell lines from Nocardia asteroides

Kokubo S., Suenaga K., Shinohara C., Tsuji T., Uemura D.

Tetrahedron 56 ( 35 ) 6435 - 6440 2000.08

Accepted,  ISSN  0040-4020

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<p>Two new lipopeptides, amamistatins A and B, were isolated from Nocardia asteroides SCRC-A2359, and their absolute stereostructures were determined by spectroscopic and chemical analyses. Amamistatin A inhibited the growth of human rumor cell lines. (C) 2000 Elsevier Science Ltd.</p>

Pinnamine, an alkaloidal marine toxin, isolated from Pinna muricata

Takada N., Iwatsuki M., Suenaga K., Uemura D.

Tetrahedron Letters 41 ( 33 ) 6425 - 6428 2000.08

Accepted,  ISSN  0040-4039

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<p>Pinnamine, a novel marine alkaloid, was isolated from the Okinawan bivalve Pinna muricata. Pinnamine was determined to be an alkaloid containing a dihydropyrone ring by spectroscopic analysis. The relative stereostructure of pinnamine was determined by an analysis of coupling constants and NOE experiments; the absolute stereostructure was determined by an analysis of the circular dichroism spectrum. Pinnamine exhibited significant acute toxicity against mice. (C) 2000 Elsevier Science Ltd.</p>

Isolation and structure of kasarin, a novel azetinone compound, isolated from a marine microorganism

Suenaga Kiyotake, Aoyama Sachiko, Xi Wang, Arimoto Hirokazu, Yamaguchi Kohji, Yamada Kaoru, Tsuji Tomoko, Yamada Akihiro, Uemura Daisuke

Heterocycles 52 ( 3 ) 1033 - 1036 2000.03

Accepted,  ISSN  0385-5414

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<p>Kasarin (1), a novel azetinone compound, was isolated from a marine microorganism. The gross structure of kasarin was elucidated by spectroscopic analyses. Kasarin exhibited antibacterial activity and weak cytotoxicity.</p>

Isolation and structures of haterumalides NA, NB, NC, ND, and NE, novel macrolides from an Okinawan sponge Ircinia sp.

Takada Noboru, Sato Hiroko, Suenaga Kiyotake, Arimoto Hirokazu, Yamada Kaoru, Ueda Katsuhiro, Uemura Daisuke

Tetrahedron Letters 40 ( 34 ) 6309 - 6312 1999.08

Accepted,  ISSN  0040-4039

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<p>Novel macrolides, haterumalides NA (1), NB (2), NC (3), ND (4), and NE (5), were isolated from an Okinawan sponge Ircinia sp. The absolute stereostructure of 1 was determined by spectroscopic analysis and modified Mosher's method. Haterumalide NA (1) showed cytotoxicity against P388 cells and acute toxicity against mice.</p>

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Structures of amamistatins A and B, novel growth inhibitors of human tumor cell lines from an actinomycete

Suenaga K., Kokubo S., Shinohara C., Tsuji T., Uemura D.

Tetrahedron Letters 40 ( 10 ) 1945 - 1948 1999.03

Accepted,  ISSN  0040-4039

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<p>Two new lipopeptides, amamistatins A (1) and B, were isolated from an actinomycete. The absolute stereostructure of 1 was determined by spectroscopic and chemical analyses. Amamistatins A (1) and B showed growth inhibition for human tumor cell lines.</p>

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Isolation and structures of attenols A and B. novel bicyclic triols from the Chinese bivalve Pinna attenuata

Takada Noboru, Suenaga Kiyotake, Yamada Kaoru, Zheng Shu Zhen, Chen Hai Sheng, Uemura Daisuke

Chemistry Letters  ( 10 ) 1025 - 1026 1999

Accepted,  ISSN  0366-7022

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<p>Novel bicyclic triols, attenols A (1) and B (2), were isolated from the Chinese bivaive Pinna attenuata. The absolute stereostructures of 1 and 2 were determined by spectroscopic analysis and the modified Mosher's method. These attenols exhibited moderate cytotoxicity against P388 cells.</p>

Aurilol, a cytotoxic bromotriterpene isolated from the sea hare Dolabella auricularia

Suenaga K., Shibata T., Takada N., Kigoshi H., Yamada K.

Journal of Natural Products 61 ( 4 ) 515 - 518 1998.04

Accepted,  ISSN  0163-3864

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<p>Aurilol (1), a novel cytotoxic bromotriterpene, was isolated from the sea hare Dolabella auricularia. The structure of 1, including the absolute stereochemistry of the five stereocenters, was determined by spectroscopic and chemical analyses. Aurilol (1) exhibited cytotoxicity against HeLa S₃ cells with an IC₅₀ of 4.3 μg/mL.</p>

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Synthesis of the aglycon of aurisides A and B, cytotoxic macrolide glycosides of marine origin

Sone Hiroki, Suenaga Kiyotake, Bessho Yuhki, Kondo Takashi, Kigoshi Hideo, Yamada Kiyoyuki

Chemistry Letters  ( 1 ) 85 - 86 1998.01

Accepted,  ISSN  0366-7022

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<p>The synthesis of the aglycon of aurisides A and B was achieved from (R)-pantolactone in 29 steps using the Nozaki reaction and the Yamaguchi macrolactonization as key steps.</p>

Cytotoxicity and actin depolymerizing activity of aplyronine A, a potent antitumor macrolide of marine origin, and the natural and artificial analogs

Suenaga Kiyotake, Kamei Noriyuki, Okugawa Youko, Takagi Masaki, Akao Atsushi, Kigoshi Hideo, Yamada Kiyoyuki

Bioorganic and Medicinal Chemistry Letters 7 ( 3 ) 269 - 274 1997.02

Accepted,  ISSN  0960-894X

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<p>The artificial analogs of aplyronine A (1), a potent cytotoxic and antitumor macrolide, were synthesized and the structure-activity (cytotoxicity and actin depolymerizing activity) studies were performed; the side chain portion in 1 was found to play a key role in both biological activities.</p>

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Enantioselective Synthesis of Aurilide, a Cytotoxic 26-Membered Cyclodepsipeptide of Marine Origin

Mutou Tsuyoshi, Suenaga Kiyotake, Fujita Tatsuya, Itoh Takashi, Takada Noboru, Hayamizu Kozue, Kigoshi Hideo, Yamada Kiyoyuki

Synlett 1997 ( 2 ) 199 - 201 1997.02

ISSN  0936-5214

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<p>Aurilide (1), a novel cyclodepsipeptide isolated from the Japanese sea hare Dolabella auricularia, was enantioselectively synthesized, and the present result unambiguously confirmed its stereostructure. In addition, the cytotoxicity of 1 was evaluated by employing synthetic 1.</p>

Dolabelides C and D, cytotoxic macrolides isolated from the sea hare Dolabella auricularia

Suenaga Kiyotake, Nagoya Tomohiro, Shibata Takunobu, Kigoshi Hideo, Yamada Kiyoyuki

Journal of Natural Products 60 ( 2 ) 155 - 157 1997.02

Accepted,  ISSN  0163-3864

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<p>Two new cytotoxic 24-membered macrolides, dolabelides C and D, were isolated from the Japanese sea hare Dolabella auricularia. Their gross structures were deduced by spectroscopic analysis including the 2D NMR technique, and their absolute stereochemistry was determined by means of chemical correlation with the known dolabelide A. Dolabelides C and D exhibited cytotoxicities against HeLa S₃ cells with IC₅₀ values of 1.9 and 1.5 μg/mL, respectively.</p>

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Isolation and stereostructure of aurilide, a novel cyclodepsipeptide from the Japanese sea hare Dolabella auricularia

Suenaga Kiyotake, Mutou Tsuyoshi, Shibata Takunobu, Itoh Takashi, Kigoshi Hideo, Yamada Kiyoyuki

Tetrahedron Letters 37 ( 37 ) 6771 - 6774 1996.09

Accepted,  ISSN  0040-4039

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<p>Aurilide (1), a new 26-membered cyclodepsipeptide, has been isolated from the Japanese sea hare Dolabella auricularia. The gross structure of 1 was established by spectroscopic analysis. The absolute stereostructure of 1 was determined by HPLC analysis of amino acid components and isoleucic acid obtained from acidic hydrolysis of 1 and by the enantioselective synthesis of the tris(p-bromobenzoate) 3 derived from the dihydroxy acid moiety.</p>

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Aplyronine A, a potent antitumor substance of marine origin, aplyronines B and C, and artificial analogues

Kigoshi Hideo, Suenaga Kiyotake, Mutou Tsuyoshi, Ishigaki Takeshi, Atsumi Toshiyuki, Ishiwata Hiroyuki, Sakakura Akira, Ogawa Takeshi, Ojika Makoto, Yamada Kiyoyuki

Journal of Organic Chemistry 61 ( 16 ) 5326 - 5351 1996.08

Accepted,  ISSN  0022-3263

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<p>The enantioselective total synthesis of aplyronine A (1), a potent antitumor substance of marine origin, was achieved by a convergent approach. Three segments 4, 5, and 6, corresponding to the C5-C11, C21-C27, and C28-C34 portions of aplyronine A (1), were prepared using the Evans aldol reaction and the Sharpless epoxidation as key steps. The coupling reaction of 4 with iodide 7 followed by Julia olefination with sulfone 8 gave the C5-C20 segment 9, while the Julia coupling reaction between segments 5 and 6 provided the C21-C34 segment 10. Julia olefination between segments 9 and 10 and the subsequent four-carbon homologation reaction led to seco acid 83, which was converted into aplyronine A (1) by Yamaguchi lactonization followed by the introduction of two amino acids. The use of the [(3,4-dimethoxybenzyl)oxy]methyl group as a protecting group for the hydroxyl at C29 was crucial for this synthesis. The enantioselective synthesis of two natural congeners, aplyronines B (2) and C (3), was also carried out using the intermediates for the synthesis of 1, which determined the absolute stereostructures of 2 and 3 unambiguously. To study the structure-cytotoxicity relationships of aplyronines, artificial analogues of 1 were synthesized and their cytotoxicities were evaluated: the trimethylserine moiety, two hydroxyl groups, and the side chain portion in 1 turned out to be important in the potent cytotoxicity shown by 1. Biological studies with aplyronine A (1) showed that 1 inhibited polymerization of G-actin to F-actin and depolymerized F-actin to G-actin.</p>

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Auripyrones A and B, cytotoxic polypropionates from the sea hare Dolabella auricularia

Suenaga Kiyotake, Kigoshi Hideo, Yamada Kiyoyuki

Tetrahedron Letters 37 ( 29 ) 5151 - 5154 1996.07

Accepted,  ISSN  0040-4039

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<p>Two new polypropionates, auripyrones A (1) and B (2), have been isolated as cytotoxins from the sea hare Dolabella auricularia. The gross structures of 1 and 2 were determined by spectroscopic analysis, and their relative stereochemistry except for the ester moiety of 2 was established on the basis of the NOESY data.</p>

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Absolute stereochemistry and synthesis of aplyronines B and C, the congeners of aplyronine A, a potent antitumor substance of marine origin

Suenaga Kiyotake, Ishigaki Takeshi, Sakakura Akira, Kigoshi Hideo, Yamada Kiyoyuki

Tetrahedron Letters 36 ( 28 ) 5053 - 5056 1995.07

Accepted,  ISSN  0040-4039

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<p>Synthesis of aplyronines B and C, the congeners of aplyronine A, was achieved enantioselectively, which established their stereostructures.</p>

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