Papers - Suenaga, Kiyotake

Biselides A and B, novel macrolides from the okinawan ascidian didemnidae sp.

Teruya Toshiaki, Shimogawa Hiroki, Suenaga Kiyotake, Kigoshi Hideo

Chemistry Letters 33 ( 9 ) 1184 - 1185 2004.09

Accepted,  ISSN  0366-7022

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<p>Two new macrolides, biselides A (1) and B (2), were isolated from the Okinawan ascidian Didemnidae sp. Their structures were determined by spectroscopic analysis.</p>

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Total synthesis of (-)-ent-jolkinolide D

Suenaga Kiyotake, Takayanagi Yui, Yamaura Masashi, Kigoshi Hideo

Chemistry Letters 33 ( 7 ) 918 - 919 2004.07

Accepted,  ISSN  0366-7022

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<p>The first total synthesis of the enantiomer of jolkinolide D, a bioactive diterpene from Euphorbia jolkini Boiss, was achieved from abietic acid. The enantiomer did not exhibit the biological activities that the natural jolkinolide D possesses.</p>

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Synthesis and actin-depolymerizing activity of mycalolide analogs

Suenaga Kiyotake, Miya Saori, Kuroda Takeshi, Handa Tomohisa, Kanematsu Kengo, Sakakura Akira, Kigoshi Hideo

Tetrahedron Letters 45 ( 28 ) 5383 - 5386 2004.07

Accepted,  ISSN  0040-4039

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<p>Mycalolide analog 4, consisting only of the side chain of mycalolide B (2), was stereoselectively synthesized and was found to have strong actin-depolymerizing activity.</p>

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Inducing substance for abalone larval metamorphosis from the crustose coralline alga Hydrolithon samoense

Suenaga Kiyotake, Hori Hidenari, Ishida Hitoshi, Nukaya Haruo, Roberts Rodney D., Tsuji Kuniro

Fisheries Science 70 ( 2 ) 342 - 344 2004.04

Accepted,  ISSN  0919-9268

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Bioorganic Studies on Marine Natural Products with Bioactivity, Such as Antitumor Activity and Feeding Attractance

Suenaga Kiyotake

Bulletin of the Chemical Society of Japan 77 ( 3 ) 443 - 451 2004.03

Accepted,  ISSN  0009-2673

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<p>This account describes bioorganic studies on marine natural products with bioactivity, such as antitumor activity and feeding attractance. Chemical studies on the following bioactive compounds of marine origin have been carried out: 1) feeding attractants for the starfish Acanthaster planci, 2) potent toxins from shellfish of the genus Pinna that cause food poisoning, and 3) a variety of cytotoxic and antitumor compounds from marine invertebrates including sea hares, Dolabella auricularia and Aplysia kurodai. Their isolation, structure elucidation, synthesis, and some aspects of their biological activities are summarized.</p>

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Isolation of tribromoacetamide from an okinawan alga and biological activities of its analogs

Kigoshi Hideo, Ichino Takao, Takada Noboru, Suenaga Kiyotake, Yamada Akihiro, Yamada Kaoru, Uemura Daisuke

Chemistry Letters 33 ( 2 ) 98 - 99 2004.02

Accepted,  ISSN  0366-7022

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<p>Tribromoacetamide was isolated from the Okinawan alga Wrangelia species, and the biological activities of this compound and its analogs were investigated.</p>

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Nakiterpiosin, a novel cytotoxic C-nor-D-homosteroid from the Okinawan sponge Terpios hoshinota

Teruya Toshiaki, Nakagawa Satoru, Koyama Tomoyuki, Suenaga Kiyotake, Kita Masaki, Uemura Daisuke

Tetrahedron Letters 44 ( 28 ) 5171 - 5173 2003.07

Accepted,  ISSN  0040-4039

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<p>A novel cytotoxic compound, nakiterpiosin (1), was isolated from the Okinawan sponge Terpios hoshinota. Its structure was determined by spectroscopic analysis. The absolute stereostructure of 1 was also determined by a modified Mosher's method. Nakiterpiosin showed potent cytotoxicity against P388 cells.</p>

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Haterumaimides J and K, potent cytotoxic diterpene alkaloids from the ascidian Lissoclinum species

Uddin M. Jasim, Kokubo Susumu, Ueda Katsuhiro, Suenaga Kiyotake, Uemura Daisuke

Chemistry Letters  ( 10 ) 1028 - 1029 2002.10

Accepted,  ISSN  0366-7022

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<p>Two unique cytotoxic diterpene alkaloids, haterumaimides J and K, were isolated from the ascidian Lissoclinum sp. Their structures were elucidated by an extensive analysis of spectral data. Haterumaimides J and K showed potent cytotoxicity against P388 cells, with IC₅₀ values of 0.23 ng/mL and 0.45 ng/mL, respectively.</p>

Hedathiosulfonic acids A and B, novel thiosulfonic acids from the deep-sea urchin Echinocardium cordatum

Kita Masaki, Watanabe Masami, Takada Noboru, Suenaga Kiyotake, Yamada Kaoru, Uemura Daisuke

Tetrahedron 58 ( 32 ) 6405 - 6412 2002.08

Accepted,  ISSN  0040-4020

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<p>Hedathiosulfonic acids A and B were isolated from the deep-sea urchin Echinocardium cordatum and were determined to be novel 6-undecanethiosulfonic acids by 2D NMR, HRMS, and methylation reaction. The stereostructure of hedathiosulfonic acid A was determined by the analysis of its degradation product, a cyclic β-hydroxysulfone. Hedathiosulfonic acids exhibited acute toxicity. We carried out various model reactions of the olefinic compounds with thiosulfonic acids and proved that, as is the case with natural products, synthesized thiosulfonic acid possessing a carbon-carbon double bond was converted into β-hydroxysulfone in the presence of oxygen.</p>

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Total synthesis of attenols A and B

Araki Keisuke, Suenaga Kiyotake, Sengoku Tetsuya, Uemura Daisuke

Tetrahedron 58 ( 10 ) 1983 - 1995 2002.03

Accepted,  ISSN  0040-4020

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<p>The enantioselective synthesis of attenols A and B, cyclic polyethers of marine origin, was accomplished on a semigram scale by using diastereoselective hydroboration, coupling with lithium acetylide, Lindlar reduction and acid-catalyzed acetal formation. The configuration of the remaining undetermined spiro acetal carbon was unambiguously determined to be 11S using this ample supply of attenol A. The antitumor activities of synthetic attenol A were also examined.</p>

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Cytotoxicity and actin-depolymerizing activity of aplyronine A, a potent antitumor macrolide of marine origin, and its analogs

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

Tetrahedron 58 ( 6 ) 1075 - 1102 2002.02

Accepted,  ISSN  0040-4020

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

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Terpiodiene, a Novel Tricyclic Alcohol from the Okinawan Sponge Terpios hoshinota.

Teruya Toshiaki, Nakagawa Satoru, Koyama Tomoyuki, Suenaga Kiyotake, Uemura Daisuke

Chemistry Letters  ( 1 ) 38 - 39 2002.01

Accepted,  ISSN  0366-7022

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<p>Terpiodiene (1), a novel tricyclic alcohol, was isolated from the Okinawan sponge Terpios hoshinota, which overgrows and kills corals. Its structure was determined by spectroscopic analysis and the modified Mosher's method. This compound exhibited moderate cytotoxicity against P388 cells.</p>

Arachidonic acid and α-linolenic acid, feeding attractants for the crown-of-thorns sea star Acanthaster planci, from the sea urchin Toxopneustes pileolus

Teruya Toshiaki, Suenaga Kiyotake, Koyama Tomoyuki, Nakano Yoshikatsu, Uemura Daisuke

Journal of Experimental Marine Biology and Ecology 266 ( 2 ) 123 - 134 2001.12

Accepted,  ISSN  0022-0981

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<p>In the tropical zones of the Indo-Pacific Oceans, the crown-of-thorns sea star Acanthaster planci, as the predator of corals, destroys coral reefs. We recently found that viscera of the sea urchin Toxopneustes pileolus produced a feeding attractant for this sea star. Using our simple bioassay system, we isolated arachidonic acid and α-linolenic acid as feeding attractants from T. pileolus. This is the first report about the sea star A. planci being attracted to unsaturated fatty acids. Interestingly, other unsaturated fatty acids such as eicosapentaenoic acid, docosahexaenoic acid and linoleic acid showed no activity. Our preliminary experiments indicated that these attractants have an attractive effect for the sea star both in the aquarium and in the sea. We anticipated that these attractants could be used to control A. planci. In addition, we verified the existence of arachidonic acid in the coral as one of the feeding attractants.</p>

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Auriculol, a cytotoxic oxygenated squalene from the Japanese sea hare Dolabella auricularia

Kigoshi Hideo, Itoh Takashi, Ogawa Takafumi, Ochi Kenya, Okada Mayuko, Suenaga Kiyotake, Yamada Kiyoyuki

Tetrahedron Letters 42 ( 42 ) 7461 - 7464 2001.10

Accepted,  ISSN  0040-4039

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<p>Auriculol, a cytotoxic oxygenated squalene, was isolated from the Japanese sea hare Dolabella auricularia, and its stereostructure was elucidated by spectral analysis and organic synthesis.</p>

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Catharsitoxins from the Chinese remedy qiung laug

Suenaga Kiyotake, Shimogawa Hiroki, Nakagawa Satoru, Uemura Daisuke

Tetrahedron Letters 42 ( 40 ) 7079 - 7081 2001.10

Accepted,  ISSN  0040-4039

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<p>Novel imidazole compounds, catharsitoxins A, B, C, D, E and F, were isolated from the Chinese remedy qiung laug. Their structures were determined by 2D NMR. To confirm their structures and to ensure an adequate supply for further biological studies, catharsitoxins A and D were synthesized.</p>

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Isolation and structures of hedathiosulfonic acids A and B, novel thiosulfonic acids from the deep-sea urchin Echinocardium cordatum

Takada Noboru, Watanabe Masami, Suenaga Kiyotake, Yamada Kaoru, Kita Masaki, Uemura Daisuke

Tetrahedron Letters 42 ( 37 ) 6557 - 6560 2001.09

Accepted,  ISSN  0040-4039

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<p>Hedathiosulfonic acids A and B were isolated from the deep-sea urchin Echinocardium cordatum, and were determined to be novel 6-undecanethiosulfonic acids by 2D NMR, HRMS, and methylation reaction. Hedathiosulfonic acids exhibited acute toxicity.</p>

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Haterumaimides F-I, four new cytotoxic diterpene alkaloids from an ascidian Lissoclinum species

Uddin M. J., Kokubo S., Ueda K., Suenaga K., Uemura D.

Journal of Natural Products 64 ( 9 ) 1169 - 1173 2001.09

Accepted,  ISSN  0163-3864

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<p>Four new monochlorinated diterpene alkaloids, haterumaimides F-I (1-4), and two known ones, dichlorolissoclimide and chlorolissoclimide, were isolated from an ascidian Lissoclinum sp. Their structures with absolute stereochemistries were elucidated by chemical and spectral analyses. Haterumaimides F-I (1-4) inhibited the first cleavage of fertilized sea urchin eggs and exhibited potent to weak cytotoxicities against P388 cells.</p>

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Zamamistatin, a significant antibacterial bromotyrosine derivative, from the Okinawan sponge Pseudoceratina purpurea

Takada Noboru, Watanabe Reiko, Suenaga Kiyotake, Yamada Kaoru, Ueda Katsuhiro, Kita Masaki, Uemura Daisuke

Tetrahedron Letters 42 ( 31 ) 5265 - 5267 2001.07

Accepted,  ISSN  0040-4039

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<p>Zamamistatin was isolated from the Okinawan sponge Pseudoceratina purpurea. It was determined to be a novel bromotyrosine derivative by careful analysis of 2D NMR spectra and comparison of its ¹H NMR spectrum with those of structurally related compounds. The absolute stereostructure of zamamistatin was determined by the modified Mosher's method. Zamamistatin exhibited significant antibacterial activity against Rhodospirillum salexigens, which has adhering properties.</p>

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Structural determination of pteriatoxins A, B and C, extremely potent toxins from the bivalve Pteria penguin

Takada Noboru, Umemura Naoyashi, Suenaga Kiyotake, Uemura Daisuke

Tetrahedron Letters 42 ( 20 ) 3495 - 3497 2001.05

Accepted,  ISSN  0040-4039

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<p>Pteriatoxins A, B and C, extremely potent toxins, were isolated from the Okinawan bivalve Pteria penguin. Their structures were determined based on NMR and MS/MS spectral analyses. Pteriatoxins have polyether macrocycles composed of 6,7-spiro, 5,6-bicyclo and 6,5,6-trispiro ketal rings, the same as in pinnatoxins.</p>

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Pinnatoxins B and C, the most toxic components in the pinnatoxin series from the Okinawan bivalve Pinna muricata

Takada Noboru, Umemura Naoyoshi, Suenaga Kiyotake, Chou Tong, Nagatsu Akito, Haino Takeharu, Yamada Kaoru, Uemura Daisuke

Tetrahedron Letters 42 ( 20 ) 3491 - 3494 2001.05

Accepted,  ISSN  0040-4039

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<p>Pinnatoxins B and C, the most toxic components in the pinnatoxin series, were successfully purified from the Okinawan bivalve Pinna muricata. Their gross structures were determined based on NMR and MS/MS spectral analyses. Their stereostructures were mainly determined by transformation reactions. Pinnatoxins B and C, C-34 epimers of each other, have an amphoteric macrocycle composed of 6,7-spiro, 5,6-bicyclo and 6,5,6-trispiro ketal rings, the same as in pinnatoxins A and D.</p>

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