Faculty Profiles - KUBOTA Takaaki

MISC - KUBOTA Takaaki

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ユズリハ科植物由来の新規アルカロイドCalyciphylline H〜Mの構造

八幡弘子, 齊藤静夏, 久保田高明, 小原祐太郎, 中畑則道, 小林淳一

日本薬学会年会要旨集 128th ( 2 ) 12 2008.3

沖縄産海綿Amphimedon sp.由来の新規アルカロイドNakinadine Aの構造

久保田高明, 西貴美, 佐々木琢磨, 小林淳一

日本薬学会年会要旨集 128th ( 2 ) 12 2008.3

Multi Phenotypic Screeningによる生理活性物質の作用解析

風見紗弥香, 風見紗弥香, 臼井健郎, 臼井健郎, 久保田高明, 小林淳一, 長田裕之, 長田裕之

日本農芸化学会大会講演要旨集 2008 9 2008.3

アスヒカズラより単離した新規アルカロイドの構造

久保田高明, 八幡弘子, 石内勘一郎, 小林淳一

日本生薬学会年会講演要旨集 54th 226 2007.9

P-11 Calyciphyllines C〜G, Novel Daphniphyllum Alkaloids from Daphniphyllum calycinum

Saito Shizuka, Kubota Takaaki, Fukushi Eri, Kawabata Jun, Zhang Huiping, Kobayashi Jun'ichi

Symposium on the Chemistry of Natural Products, symposium papers 0 ( 49 ) 271 - 276 2007.8

Language：Japanese Publisher：Symposium on the chemistry of natural products

DOI： 10.24496/tennenyuki.49.0_271

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ユズリハ科植物由来の新規アルカロイドcalyciphylline C〜Gの構造と生物活性

齊藤静夏, 久保田高明, 福士江里, 川端潤, ZHANG Huiping, 小林淳一

天然有機化合物討論会講演要旨集 49th ( 49 ) 271-276 - 276 2007.8

Language：Japanese Publisher：Symposium on the chemistry of natural products

Daphniphyllum alkaloids are a structually diverse group of natural products with unique fused-heterocyclic skeletons, which are elaborated by trees of the genus Daphniphyllum (Daphniphyllaceae). These unusual ring systems have been challenging targets for total synthesis as well as biosynthetic studies. We have isolated novel types of Daphniphyllum alkaloids from Daphniphyllum macropodum, D. humile, D. teijsmanni, and D. glaucescense. In our continuing search for structually unique and biogenetically interesting new alkaloids, calyciphyllines C-G (1-5) have been isolated from D. calycinum, and their structures and relative stereochemistry were elucidated on the basis of spectroscopic data. Calyciphylline C (1) is a novel Daphniphyllum alkaloid with an unprecedented fused-hexacyclic skeleton having an azetidine ring. Calyciphyllines D (2) and F (4) are novel alkaloids containing a unique fused-pentacyclic skeleton with a 8-azatricyclo[4.2.1.0.^<4,8>]nonane ring system. Calyciphylline E (3) is a new alkaloid with a fused-heptacyclic ring system, while calyciphylline G (5) is a novel alkaloid possessing an unprecedented fused-hexacyclic skeleton containg 5-azatricyclo[6.2.1.0]undecane ring system. Effects of these alkaloids on neurotrophic factor biosynthesis in 1321N1 human astrocytoma cells were examined by a semiquantitative RT-PCR method to find that the mRNA expressions for NGF were enhanced.

DOI： 10.24496/tennenyuki.49.0_271

ケミカルバイオロジー研究のフロンティア創薬リードとしての分子標的天然薬物の探索

小林淳一, 久保田高明

現代化学 ( 436 ) 21-26 - 26 2007.7

創薬リードとしての分子標的天然薬物の探索

小林淳一, 久保田高明

現代化学 0 ( 436 ) 21 - 26 2007.7

渦鞭毛藻由来の新規amphidinolide関連化合物の構造

高橋洋平, 久保田高明, 小林淳一

次世代を担う有機化学シンポジウム講演要旨集 5th 6-7 2007.5

免疫抑制物質brasilicardin Aの標的分子同定

臼井健郎, 臼井健郎, 南雲陽子, 南雲陽子, 渡邉愛, 久保田高明, 小林淳一, 長田裕之

日本農芸化学会大会講演要旨集 2007 98 2007.3

1 Agesamides and Nagelamides, Novel Bromopyrrole Alkaloids from Sponge Agelas spp.

Yasuda Tetsuro, Araki Atsushi, Tsuda Masashi, Kubota Takaaki, Fukushi Eri, Kawabata Jun, Kobayashi Jun'ichi

Symposium on the Chemistry of Natural Products, symposium papers 49 ( 0 ) 1 - 6 2007

Language：Japanese Publisher：Symposium on the Chemistry of Natural Products Steering Committee

Diffusion-ordered NMR spectroscopy (DOSY) is a versatile and powerful NMR technique and a noninvasive analytical method for mixture analysis that does not require prior physical separation of the analysis. In our search for new metabolites from natural resources, DOSY was applied for constituent analysis of crude bromopyrrole fractions separated from an Okinawan marine sponge Agelas sp. (SS-1056) so that two new bromopyrrole alkaloids, agesamides A (1) and B (2), have been isolated. The structures and relative stereochemistry of 1 and 2 were elucidated fromspectroscopic data. Furthermore, two new bromopyrrole alkaloids, nagelamides J (3) and K (4), have been isolated from another Okinawan marine sponge Agelas sp. (SS-1077), and the structures and relative stereochemistries were elucidated from spectroscopic data. Nagelamide J (3) is the first bromopyrrole alkaloid possessing a cyclopentane ring fused to an amino imidazole ring and nagelamide K (4) is a unique dimeric bromopyrrole alkaloid containing an ester linkage. Nagelamide J (3) exhibited antimicrobial activity against Staphylococcus aureus (MIC, 8.35μg/ml) and antifungal activity against Cryptococcus neoformans (MIC, 16.7μg/ml), while nagelamide K (4) exhibited antimicrobial activity against Micrococcus luteus (MIC, 16.7μg/ml).

DOI： 10.24496/tennenyuki.49.0_1

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1 Agesamides and Nagelamides, Novel Bromopyrrole Alkaloids from Sponge Agelas spp.

Yasuda Tetsuro, Araki Atsushi, Tsuda Masashi, Kubota Takaaki, Fukushi Eri, Kawabata Jun, Kobayashi Jun'ichi

Symposium on the Chemistry of Natural Products, symposium papers 49 ( 0 ) 1 - 6 2007

Language：Japanese Publisher：Symposium on the Chemistry of Natural Products Steering Committee

DOI： 10.24496/tennenyuki.49.0_1

STRUCTURES AND PLAUSIBLE BIOGENETIC PATHWAY FOR NOVEL ALKALOIDS FROM DAPHNIPHYLLUM SPECIES

MATSUNO YOSUKE, OKAMOTO MARIKO, ZAIMA KAZUMASA, KUBOTA TAKAAKI, KOBAYASHI JUN'ICHI, SHINZATO TAKAKAZU, MORITA HIROSHI

薬学雑誌 126 ( Suppl.5 ) 100-103 - 103 2006.11

ABSOLUTE STEREOCHEMISTRY AND MOLECULAR TARGET OF ANTITUMOR MACROLIDES, IEJIMALIDES

KUBOTA TAKAAKI, NOZAWA KOHEI, TSUDA MASASHI, ISHIYAMA HARUAKI, KAZAMI SAYAKA, USUI TAKEO, OSADA HIROYUKI, KOBAYASHI JUN'ICHI

薬学雑誌 126 ( Suppl.5 ) 222-225 2006.11

アスヒカズラLycopodium complanatum由来の新規アルカロイドの構造と生物活性

石内勘一郎, 久保田高明, 森田博史, 星野智洋, 小原祐太郎, 中畑則道, 小林淳一

天然有機化合物討論会講演要旨集 48th ( 48 ) 493-498 - 498 2006.9

Language：Japanese Publisher：Symposium on the chemistry of natural products

Club moss (Lycopodiaceae) is known to be a rich source of Lycopodium alkaloids posessing unique heterocyclic ring systems such as C_<16>N, C_<16>N_2, and C_<27>N_3, which have attracted great interest from biogenetic, synthetic, and biological points of view. In our continuing efforts to find new Lycopodium alkaloids, lycopladines A-D (1-4), lyconadin B (5), and complanadines C (6), D (7) were isolated from the club moss Lycopodium complanatum. The structures for 1-7 were elucidated on the basis of spectral data. Lycopladine A (1) obtained as colorless amourphous solid, showed the pseudomolecular ion peak at m/z 260 (M+H)^+ in the ESIMS, and the molecular formula, C_<16>H_<21>NO_2, was established by HRESIMS [m/z 260.1653, (M+H)^+, △+0.2mmu]. The gross structure of 1 was elucidated on the basis of 2D NMR data. The relative stereochemistry of 1 was elucidated from NOESY data. Lycopladine A (1) possesses an unprecedented skeleton different from known C_<16>N-type Lycopodium alkaloids. The stuructures of lycopladines B-D (2-4) were elucidated on the basis of spectroscopic data and modified Mosher's method. Lycopladine B (2) was 5-hydroxyl, △_<8,15>, △_<13,14>, and 17-methyl ester form of fawcettidane skeleton. Lycopladine C (3) was assigned as 5-O-acetyl form of 2. Lycopladine D (4) had fawcettidane skeleton with hydroxyl group at C-5 and lactone ring (C-13〜C-16). The absolute stereochemistry of 2 and 4 were elucidated by modified Mosher's method. The absolute configuration at C-5 of 2 and 4 were assigned to be S and R, respectively. Lyconadin B (5) was assigned as dihydro form of lyconadin A. Complanadines C (6) and D (7) were obtained as colorless amorphous solids. The structures and relative stereochmistry of 6 and 7 were elucidated on the basis of spectroscopic data. Complanadine C (6) was assigned as the dimer of 9-keto, △_<10,11> form of lycopodine and △_<9,10> form of lycopodine. The dimer of lycopodane skeleton has not been reported previously. Complanadine D (7) was tetrahydro form of complanadine A. A plausible biogenetic path of lyconadin A (8) was proposed on the basis of structure of lycopladine A (1). Biogenetically, lyconadines A (8) and B (5) might be derived from L-lysine via pelletierine, phlegmarane skeleton, and an intermediate X from which lycopladine A (1) might be provided. Effects of lycopladines A-D (1-4), and lyconadins A (8) and B (5) on neurotrophic factor biosynthesis in 1321N1 human astrocytoma cells were examined. The mRNA expressions of NGF in 1321N1 cells were examined by a semiquantitative RT-PCR method. The mRNA expressions for NGF were enhanced by lyconadins A (8) and B (5).

DOI： 10.24496/tennenyuki.48.0_493

P-16 Structures and Biological Activity of New Lycopodium Alkaloids from Lycopodium complanatum

Ishiuchi Kan'ichiro, Kubota Takaaki, Morita Hiroshi, Hoshino Tomohiro, Obara Yutaro, Nakahata Norimichi, Kobayashi Jun'ichi

Symposium on the Chemistry of Natural Products, symposium papers 0 ( 48 ) 493 - 498 2006.9

Language：Japanese Publisher：Symposium on the chemistry of natural products

DOI： 10.24496/tennenyuki.48.0_493

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