The Experts below are selected from a list of 375 Experts worldwide ranked by ideXlab platform
Kiyoyuki Yamada - One of the best experts on this subject based on the ideXlab platform.
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Cytotoxic substances from two species of Japanese sea hares: Chemistry and bioactivity
Proceedings of the Japan Academy. Series B Physical and biological sciences, 2010Co-Authors: Kiyoyuki Yamada, Hideo Kigoshi, Makoto Ojika, Kiyotake SuenagaAbstract:From the sea hares belonging to two genera, Aplysia and Dolabella, a variety of new cytotoxic substances were isolated as minute constituents: their chemical structures were determined and their cytotoxicity was evaluated. Regarding the highly cytotoxic substances, further chemical and biological studies were performed that included their asymmetric chemical synthesis and elucidation of biological characteristics such as antitumor activity.
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Auriculol, a cytotoxic oxygenated squalene from the Japanese sea hare Dolabella auricularia: isolation, stereostructure, and synthesis
Tetrahedron Letters, 2001Co-Authors: Hideo Kigoshi, Kiyotake Suenaga, Takashi Itoh, T. Ogawa, Kenya Ochi, Mayuko Okada, Kiyoyuki YamadaAbstract:Abstract 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.
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Aurilol, a Cytotoxic Bromotriterpene Isolated from the Sea Hare Dolabella auricularia
Journal of Natural Products, 1998Co-Authors: Kiyotake Suenaga, Hideo Kigoshi, Takunobu Shibata, Noboru Takada, Kiyoyuki YamadaAbstract: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.
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aurisides a and b cytotoxic macrolide glycosides from the japanese sea hare Dolabella auricularia
ChemInform, 1997Co-Authors: Hiroki Sone, Hideo Kigoshi, Kiyoyuki YamadaAbstract:Bioassay-guided fractionation of the cytotoxic constituents of the Japanese sea hare Dolabella auricularia led to the isolation of two novel cytotoxic compounds, aurisides A (1) and B (2). Their gross structures were established by spectroscopic analysis including the 2D NMR technique. On the basis of the NOESY spectral analysis and the degradation experiments, their absolute stereostructures were determined to be 14-membered macrolide glycosides that contain a bromine-substituted conjugated diene structure, a cyclic hemiacetal moiety, and a 2,4-di-O-methyl-l-rhamnopyranoside part. Aurisides A (1) and B (2) show cytotoxicity against HeLa S3 cells with IC50 values of 0.17 and 1.2 μg/mL, respectively.
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ISOLATION AND STEREOSTRUCTURE OF DOLASTATIN I, A CYTOTOXIC CYCLIC HEXAPEPTIDE FROM THE JAPANESE SEA HARE Dolabella AURICULARIA
Tetrahedron, 1997Co-Authors: Hiroki Sone, Hideo Kigoshi, Kiyoyuki YamadaAbstract:Abstract Dolastatin I (1), a cyclic hexapeptide containing three kinds of five-membered heterocycles (oxazole, thiazole, and oxazoline), has been isolated from the Japanese sea hare Dolabella auricularia. The gross structure of 1 was elucidated by spectroscopic analysis. The absolute stereostructure of 1 was determined by chiral HPLC analysis of the amino acid components obtained by acid hydrolysis of 1. Dolastatin I (1) exhibited cytotoxicity against HeLa S3 cells with an IC50 value of 12 μg/mL.
Makoto Ojika - One of the best experts on this subject based on the ideXlab platform.
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Cytotoxic substances from two species of Japanese sea hares: Chemistry and bioactivity
Proceedings of the Japan Academy. Series B Physical and biological sciences, 2010Co-Authors: Kiyoyuki Yamada, Hideo Kigoshi, Makoto Ojika, Kiyotake SuenagaAbstract:From the sea hares belonging to two genera, Aplysia and Dolabella, a variety of new cytotoxic substances were isolated as minute constituents: their chemical structures were determined and their cytotoxicity was evaluated. Regarding the highly cytotoxic substances, further chemical and biological studies were performed that included their asymmetric chemical synthesis and elucidation of biological characteristics such as antitumor activity.
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isolation and stereostructures of dolastatin g and nordolastatin g cytotoxic 35 membered cyclodepsipeptides from the japanese sea hare Dolabella auricularia
Journal of Organic Chemistry, 1996Co-Authors: Tsuyoshi Mutou, Makoto Ojika, Tadao Kondo, Kiyoyuki YamadaAbstract:A bioassay-directed fractionation of the cytotoxic constituents of the Japanese sea hare Dolabella auricularia resulted in the isolation of two 35-membered depsipeptides dolastatin G (1) and nordolastatin G (2), which showed cytotoxicity against HeLa S(3) cells with IC(50) values of 1.0 and 5.3 mg/mL, respectively. The gross structures of these substances were established by spectroscopic analysis including 2D NMR techniques. The absolute stereostructure of 1 was determined by chiral HPLC analysis of amino acid components obtained from acid hydrolysis of 1 and by the enantioselective syntheses of two degradation products arising from polyketide portions. Nordolastatin G (2) is a congener that has the same absolute stereochemistry as that of 1.
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Dolastatin H and Isodolastatin H, Potent Cytotoxic Peptides from the Sea Hare Dolabella auricularia: Isolation, Stereostructures, and Synthesis
Journal of the American Chemical Society, 1996Co-Authors: Hiroki Sone, Makoto Ojika, Takunobu Shibata, Tatsuya Fujita, Kiyoyuki YamadaAbstract:A bioassay-directed investigation of the cytotoxic constituents of the Japanese sea hare Dolabella auricularia resulted in the isolation of two cytotoxic compounds designated dolastatin H (2) and i...
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dolabelides a and b cytotoxic 22 membered macrolides isolated from the sea hare Dolabella auricularia
Tetrahedron Letters, 1995Co-Authors: Makoto Ojika, Tomohiro Nagoya, Kiyoyuki YamadaAbstract:Abstract A new 22-membered macrolides, dolabelide A ( 1 ), and its deacetyl derivative, dolabelide B ( 2 ), have been isolated as cytotoxins from the Japanese sea hare Dolabella auricularia . The gross structures of 1 and 2 were determined by spectroscopic analysis, and their absolute stereochemistry was elucidated by a combination of chemical means and the NMR spectroscopic method.
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Dolastatin E, a new cyclic hexapeptide isolated from the sea hare Dolabella auricularia
Tetrahedron Letters, 1995Co-Authors: Makoto Ojika, Takayuki Nemoto, Masayuki Nakamura, Kiyoyuki YamadaAbstract:Abstract Dolastatin E ( 1 ), a new cyclic hexapeptide containing three kinds of five-membered heterocycles (oxazole, thiazole, and thiazolone), has been isolated from the Japanese sea hare Dolabella auricularia and its gross structure elucidated by spectroscopic analysis.
Hideo Kigoshi - One of the best experts on this subject based on the ideXlab platform.
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Cytotoxic substances from two species of Japanese sea hares: Chemistry and bioactivity
Proceedings of the Japan Academy. Series B Physical and biological sciences, 2010Co-Authors: Kiyoyuki Yamada, Hideo Kigoshi, Makoto Ojika, Kiyotake SuenagaAbstract:From the sea hares belonging to two genera, Aplysia and Dolabella, a variety of new cytotoxic substances were isolated as minute constituents: their chemical structures were determined and their cytotoxicity was evaluated. Regarding the highly cytotoxic substances, further chemical and biological studies were performed that included their asymmetric chemical synthesis and elucidation of biological characteristics such as antitumor activity.
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Auriculol, a cytotoxic oxygenated squalene from the Japanese sea hare Dolabella auricularia: isolation, stereostructure, and synthesis
Tetrahedron Letters, 2001Co-Authors: Hideo Kigoshi, Kiyotake Suenaga, Takashi Itoh, T. Ogawa, Kenya Ochi, Mayuko Okada, Kiyoyuki YamadaAbstract:Abstract 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.
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Synthesis of dolastatin I, a cytotoxic cyclic hexapeptide from the sea hare Dolabella auricularia
Tetrahedron, 1999Co-Authors: Hideo Kigoshi, Shiho YamadaAbstract:Abstract Dolastatin I, a cytotoxic cyclic hexapeptide isolated from the Japanese sea hare Dolabella auricularia , was enantioselectively synthesized, which confirmed its stereostructure.
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Aurilol, a Cytotoxic Bromotriterpene Isolated from the Sea Hare Dolabella auricularia
Journal of Natural Products, 1998Co-Authors: Kiyotake Suenaga, Hideo Kigoshi, Takunobu Shibata, Noboru Takada, Kiyoyuki YamadaAbstract: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.
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aurisides a and b cytotoxic macrolide glycosides from the japanese sea hare Dolabella auricularia
ChemInform, 1997Co-Authors: Hiroki Sone, Hideo Kigoshi, Kiyoyuki YamadaAbstract:Bioassay-guided fractionation of the cytotoxic constituents of the Japanese sea hare Dolabella auricularia led to the isolation of two novel cytotoxic compounds, aurisides A (1) and B (2). Their gross structures were established by spectroscopic analysis including the 2D NMR technique. On the basis of the NOESY spectral analysis and the degradation experiments, their absolute stereostructures were determined to be 14-membered macrolide glycosides that contain a bromine-substituted conjugated diene structure, a cyclic hemiacetal moiety, and a 2,4-di-O-methyl-l-rhamnopyranoside part. Aurisides A (1) and B (2) show cytotoxicity against HeLa S3 cells with IC50 values of 0.17 and 1.2 μg/mL, respectively.
Hendrik Luesch - One of the best experts on this subject based on the ideXlab platform.
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The Cyanobacterial Origin of Potent Anticancer Agents Originally Isolated from Sea Hares
Current Medicinal Chemistry, 2002Co-Authors: Hendrik Luesch, Gilles H. Goetz, F. David HorgenAbstract:It is increasingly evident that the true biological origin of many metabolites originally isolated from certain marine macroorganisms is cyanobacterial. For example, several dolastatins, potent cytotoxic compounds originally derived from the sea hare Dolabella auricularia, have now been isolated from marine cyanobacteria of the genera Lyngbya and Symploca. This review discusses the isolation of dolastatins and close structural analogues from cyanobacteria. Biosynthetic signatures of metabolites isolated from sea hares, but which are most probably cyanobacterial in origin, are also presented. Finally, some more complex ecology involving movement of cyanobacterial metabolites through the marine food web is presented.
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isolation of dolastatin 10 from the marine cyanobacterium symploca species vp642 and total stereochemistry and biological evaluation of its analogue symplostatin 1
Journal of Natural Products, 2001Co-Authors: Hendrik Luesch, Susan L Mooberry, Richard E. Moore, Valerie J. Paul, Thomas H CorbettAbstract:The potent antitumor agent dolastatin 10 (1) was originally isolated from the sea hare Dolabella auricularia, and we now report its isolation from the marine cyanobacterium Symploca sp. VP642 from Palau. The chemically related analogue symplostatin 1 (2) has been reisolated from Guamanian and Hawaiian varieties of S. hydnoides and its total stereochemistry completed by determining the N,N-dimethylisoleucine unit to be l. Symplostatin 1 (2), like dolastatin 10 (1), is a potent microtubule inhibitor. The antitumor activity of 2 was assessed in vivo against several murine tumors. Symplostatin 1 (2) was effective against a drug-insensitive mammary tumor and a drug-insensitive colon tumor; however, it was only slightly effective against two MDR tumors.
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isolation structure determination and biological activity of lyngbyabellin a from the marine cyanobacterium lyngbya majuscula
Journal of Natural Products, 2000Co-Authors: Hendrik Luesch, Richard E. Moore, Wesley Y. Yoshida, Valerie J. Paul, Susan L MooberryAbstract:Lyngbyabellin A (1), a significantly cytotoxic compound with unusual structural features, was isolated from a Guamanian strain of the marine cyanobacterium Lyngbya majuscula. This novel peptolide is structurally related to dolabellin (2) in that both depsipeptides bear a dichlorinated β-hydroxy acid and two functionalized thiazole carboxylic acid units. Its gross structure has been elucidated by spectral analysis, including 2D NMR techniques. The absolute stereochemistry of 1 was determined by chiral HPLC analysis of hydrolysis products and by characterization of the degradation products methyl 7,7-dichloro-3-hydroxy-2,2-dimethyloctanoate (3) and the corresponding acid 4. The total structure was further supported by molecular modeling studies. The isolation of 1 from L. majuscula once more supports the proposal that many compounds originally isolated from the sea hare Dolabella auricularia are of cyanobacterial origin. Lyngbyabellin A (1) was shown to be a potent disrupter of the cellular microfilament ne...
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symplostatin 2 a dolastatin 13 analogue from the marine cyanobacterium symploca hydnoides
Journal of Natural Products, 1999Co-Authors: Hendrik Luesch, Wesley Y. Yoshida, Richard E. Moore, Valerie J. PaulAbstract:An analogue of dolastatin 13 (2) has been isolated from a marine cyanobacterium, Symploca hydnoides, collected near Guam. This new cyclic depsipeptide contains a l-methionine sulfoxide residue; however, the sulfoxide exists as both R- and S-forms, resulting in the doubling of several signals in the 1H and 13C NMR spectra. Structure elucidation required extensive application of 2-D NMR techniques such as COSY, HMQC, HMBC, and ROESY. The trivial name symplostatin 2 (1) has been assigned to the new metabolite and its isolation from S. hydnoides further supports the proposal that many compounds originally isolated from the sea hare Dolabella auricularia are most probably of cyanobacterial origin.
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symplostatin 1 a dolastatin 10 analogue from the marine cyanobacterium symploca hydnoides
Journal of Natural Products, 1998Co-Authors: Hendrik Luesch, Susan L Mooberry, Thomas H Corbett, Wesley Y. Yoshida, Richard E. Moore, Valerie J. Paul, Fred ValerioteAbstract:A new solid tumor selective cytotoxic analogue of dolastatin 10 (1) has been isolated from the marine cyanobacterium Symploca hydnoides, collected near Guam. This metabolite has been assigned the trivial name symplostatin 1 (2). This discovery supports the proposal that many compounds isolated from the seahare Dolabella auricularia, the original source of the dolastatins, are of dietary origin.
Kiyotake Suenaga - One of the best experts on this subject based on the ideXlab platform.
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Cytotoxic substances from two species of Japanese sea hares: Chemistry and bioactivity
Proceedings of the Japan Academy. Series B Physical and biological sciences, 2010Co-Authors: Kiyoyuki Yamada, Hideo Kigoshi, Makoto Ojika, Kiyotake SuenagaAbstract:From the sea hares belonging to two genera, Aplysia and Dolabella, a variety of new cytotoxic substances were isolated as minute constituents: their chemical structures were determined and their cytotoxicity was evaluated. Regarding the highly cytotoxic substances, further chemical and biological studies were performed that included their asymmetric chemical synthesis and elucidation of biological characteristics such as antitumor activity.
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Auriculol, a cytotoxic oxygenated squalene from the Japanese sea hare Dolabella auricularia: isolation, stereostructure, and synthesis
Tetrahedron Letters, 2001Co-Authors: Hideo Kigoshi, Kiyotake Suenaga, Takashi Itoh, T. Ogawa, Kenya Ochi, Mayuko Okada, Kiyoyuki YamadaAbstract:Abstract 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.
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Aurilol, a Cytotoxic Bromotriterpene Isolated from the Sea Hare Dolabella auricularia
Journal of Natural Products, 1998Co-Authors: Kiyotake Suenaga, Hideo Kigoshi, Takunobu Shibata, Noboru Takada, Kiyoyuki YamadaAbstract: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.
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dolabelides c and d cytotoxic macrolides isolated from the sea hare Dolabella auricularia
Journal of Natural Products, 1997Co-Authors: Kiyotake Suenaga, Hideo Kigoshi, Takunobu Shibata, Tomohiro Nagoya, Kiyoyuki YamadaAbstract: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 S 3 cells with IC 50 values of 1.9 and 1.5 μg/mL, respectively.
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Isolation and stereostructure of aurilide, a novel cyclodepsipeptide from the Japanese sea hare Dolabella auricularia
Tetrahedron Letters, 1996Co-Authors: Kiyotake Suenaga, Hideo Kigoshi, Tsuyoshi Mutou, Takahiro Shibata, Takashi Itoh, Kiyoyuki YamadaAbstract:Abstract 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.