研究者詳細 - 清田　洋正

論文 - 清田　洋正

分割表示 235 件中 201 - 220 件目／全件表示 >>

Three New Taxoids from the Leaves of the Japanese Yew, Taxus cuspidata

Qing-Wen Shi, Takayuki Oritani, Hiromasa Kiyota, Ryo Murakami

Natural Product Letters 15 ( 1 ) 55 - 62 2001年

125(P-66) TaxinineからTaxol analogsへの変換 : Taxinine誘導体の化学反応性(ポスター発表の部)

堀口透, 清田洋正, 程潜, 折谷隆之

天然有機化合物討論会講演要旨集 ( 42 ) 745 - 750 2000年10月

記述言語：日本語出版者・発行元：天然有機化合物討論会

Currently, diterpenoid paclitaxel (faxol^[○!R] 1) is regarded as a powerful therapeutic drug for cancer chemotherapy. 1 exhibits potent antitumor activity against various cancers that have been ineffectively treated by existing chemotherapeutic drugs, and 1 have been approved by the FDA for the treatment of advanced ovarian cancer and breast cancer. Recent studies have shown that treatment for various types of advanced solid cancers with paclitaxel and docetaxel often insults in the emergence of multi-drug resistance (MDR). Thus, it is important to explore new taxoids either with improved activity against various classes of tumors, especially against drug-resistant human cancers. Here we report the methods to convert taxinine, abundantly available from the Japanese yew leaves, to a new 2-m-azido-1,7-deoxybaccatin III analog,which would be an active substrate for the tublin depolymerization test as well as 1. We also report that the biomimetic hydroxylation of C-1 position of 2-deacetoxy-taxinine J derivative (2d) had been successfully achieved by a simple chemical oxidation using dimethyl-dioxirane (DMDO), leading to the 1β-hydroxy-4α, 20-epoxide (26) and its 4β-isomer (27). This method could not be applied for 2-acetoxy-taxoids. In addition, it was found that the change of reaction temperature could control the regioselectivity of the epoxidation between the endo- and exo-double bonds of 2-deacetoxytaxinine J (2d) with m-CPBA. Attempts of biomimetic construction of the D-ring of taxol from the 4 β, 20-epoxy-5-mesyl taxoids (17) with Lewis acid mediated reaction were unsuccessful. While the same condition could convert 22-bromo-4 β, 5β-epoxy taxoid (20) to 4, 22-spirotaxoids (21) as a sole product. These result suggest that the nucleophilic trap of carbocation (III) at 5-position by water would be prior to that at 4-position, that is, it is difficult to demonstrate the proposed biosynthetic pathway of D-ring by a synthetic method.

DOI： 10.24496/tennenyuki.42.0_745

CiNii Article

CiNii Books

researchmap

Synthesis and antifungal activity of the four stereoisomers of streptimidone, a glutarimide antibiotic from Streptomyces rimosus forma paromomycinus

H Kondo, T Oritani, H Kiyota

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY 2000 ( 20 ) 3459 - 3462 2000年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-V C H VERLAG GMBH

Four stereoisomers of streptimidone (1), an antibiotic from Streptomyces rimosus forma paromomycinus, were synthesized from methyl (S)-3-hydroxy-2-methylpropanoate. The natural diastereomer 1 shows the strongest antimicrobial activity.

DOI： 10.1002/1099-0690(200010)2000:20<3459::AID-EJOC3459>3.0.CO;2-F

Web of Science

researchmap

Synthesis of Both Enantiomers of cis-α-Irone and cis-g-Irone, Principal Constituents of Irish oil, via Optical Resolution of (±)-2,2,4-trimethyl-3-cyclohexene Carboxylic Acid

Takahiro Inoue, Hiromasa Kiyota, Takayuki Oritani

Tetrahedron: Asymmetry 11 ( 18 ) 3807 - 3818 2000年9月

Effect of fertilizer and manure application on L-glutaminase and L-asparaginase activities in soils

S Kanazawa, H Kiyota

SOIL SCIENCE AND PLANT NUTRITION 46 ( 3 ) 741 - 744 2000年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPANESE SOC SOIL SCIENCE PLANT NUTRITION

Effects of fertilizer and manure application on L-glutaminase and L-asparaginase activities on volcanic ash soil and gray lowland soil mere examined. The activities were estimated by using the indophenol method. This involved the colorimetric estimation of NH4+ released from L-glutamine or L-asparagine catalyzed by the enzymes, when the soils were incubated with 0.25 M L-glutamine or L-asparagine in 0.1 M phosphate buffer (pH 7.6) and toluene used as a germicide, Both L-glutaminase and L-asparagine activities were the largest in the farmyard manure plot (OM), followed by the chemical fertilizer plot (CF) and the plot without fertilizer application, hereafter referred to as "no fertilizer plot" (NF).

Web of Science

researchmap

Synthesis of (+-)-Methyl Bishomononactate, a Monomeric Component of Macrotetrolides

Tadaatsu Hanadate, Hiromasa Kiyota,* Takayuki Oritani

Bioscience, Biotechnology, and Biochemistry 64 ( 8 ) 1671 - 1674 2000年8月

Taxane diterpenoids from Taxus yunnanensis and Taxus cuspidata

QW Shi, T Oritani, H Kiyota, D Zhao

PHYTOCHEMISTRY 54 ( 8 ) 829 - 834 2000年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

Chemical examination of the seeds of the Chinese yew, Taxus yunnanensis Cheng et L. K. Fu and the Japanese yew, Taxus cuspidata Sieb et Zucc, resulted in the isolation of four taxane diterpenoids. The structures of these taxoids were established as (12 alpha)-2 alpha-acetoxy-5 alpha,9 alpha,10 beta-trihydroxy-3,11-cyclotax-4(20)-en-13-one; 2 alpha,7 beta,13 alpha-triacetoxy-5 alpha,9 alpha-dihydroxy-2(3 --> 20)abeotaxa-4(20),11-dien-10-one; 9 alpha,10 beta-diacetoxy-5 alpha-cinnamoyloxytaxa-4(20),11-dien-13 alpha-ol and the known 2 alpha,7 beta,9 alpha,10 beta,13-pentaacetoxytaxa-4(20),12-diene-5 alpha,11 beta-diol on the basis of spectral analysis. (C) 2000 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0031-9422(00)00186-2

Web of Science

researchmap

Synthesis of Actiketal, a Glutarimide Antibiotic

Hiromasa Kiyota,* Yuko Shimizu, Takayuki Oritani

Tetrahedron Letters 41 ( 31 ) 5887 - 5890 2000年7月

Enzymatic Resolution of (±)-Epoxy-β-cyclogeraniol, a Synthetic Precursor for Abscisic Acid Analog

Ryou Okazaki, Hiromasa Kiyota, Takayuki Oritani

Bioscience, Biotechnology, and Biochemistry 64 ( 7 ) 1444 - 1447 2000年7月

Synthesis of the spiroacetal parts of spirofungin A and B

Y Shimizu, H Kiyota, T Oritani

TETRAHEDRON LETTERS 41 ( 17 ) 3141 - 3144 2000年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

The C9-C20 spiroacetal parts of spirofungin A and B, antifungal antibiotics from Strephomyces violaceusniger Tu 4113, were synthesized simultaneously from (S)-citronellyl bromide and (+/-)-epoxy alcohol via alkyne-lactone coupling reaction and diastereomeric separation. (C) 2000 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0040-4039(00)00371-3

Web of Science

researchmap

Synthesis and antimicrobial activity of unnatural (-)-antimycin A(3) and its analog

H Kondo, T Oritani, H Kiyota

HETEROCYCLIC COMMUNICATIONS 6 ( 3 ) 211 - 214 2000年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：FREUND PUBLISHING HOUSE LTD

Unnatural enantiomer of a dilactone antibiotic (-)-antimycin A(3) and its deformylamidodehydroxy analog were synthesized using chelation controlled alkylation as a key step. (-)-Antimycin A(3) and its analog hardly showed antimicrobial activity compared with natural antimycin A complex. The formal synthesis of natural (+)-antimycin A(3) is also achieved.

Web of Science

researchmap

Synthesis of the Southern Part of Pamamycin-607, an Aerial Mycelium-Inducing Substance of Streptomyces alboniger

Yukito Furuya, Hiromasa Kiyota,* Takayuki Oritani

Heterocyclic Communications 6 ( 5 ) 427 - 430 2000年

Synthesis of (±)-Methyl Tuberonate, a Potato Tuber Forming Substance, and its Epimer

Hiromasa Kiyota, Daisuke Nakashima, Takayuki Oritani

Bioscience, Biotechnology, and Biochemistry 63 ( 12 ) 2110 - 2117 1999年12月

Hydrolase-catalyzed preparation of (R)- and (S)-4-hydroxy-2,6,6-trimethyl-2-cyclohexen-1-ones (phorenols), the key synthetic intermediates for abscisic acid

H Kiyota, M Nakabayashi, T Oritani

TETRAHEDRON-ASYMMETRY 10 ( 19 ) 3811 - 3817 1999年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

Preparation of both the enantiomers of 4-hydroxy-2,6,6-trimethyl-2-cyclohexen-1-one (phorenol), which are versatile synthetic intermediates for abscisic acid and carotenoids, was achieved by hydrolase-catalyzed hydrolysis of the corresponding chloroacetate. The hydrolysis with esterase SNSM-87 (Nagase) enriched the (S)-ester, while lipase P (Amano) afforded the (R)-ester. (C) 1999 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0957-4166(99)00391-2

Web of Science

researchmap

Synthesis of dendryphiellin C, a trinor-sesquiterpene from a marine source

H Akao, H Kiyota, T Nakajima, T Kitahara

TETRAHEDRON 55 ( 25 ) 7757 - 7770 1999年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

Enantioselective synthesis of dendryphiellin C, isolated from cultures of Dendryphiella sarina, has been achieved in a convergent way such as coupling of a C9-branched carboxylic acid 10 with a trinor-eremophilane alcohol 11. The latter was synthesized starting from a chiral building block, (1S,5S,6R)-5-hydroxybicyclo[4.1.0]heptan-2-one 16, which was originally prepared in this group using biochemical transformation as a key step. The synthesis was completed through 12 steps from 16 in overall 2.4% yield. (C) 1999 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0040-4020(99)00407-X

Web of Science

researchmap

Three new rearranged taxane diterpenoids from the bark of Taxus chinensis var. mairei and the needles of Taxus cuspidata

QW Shi, T Oritani, T Sugiyama, H Kiyota, T Horiguchi

HETEROCYCLES 51 ( 4 ) 841 - 850 1999年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD

Three new rearranged taxane diterpenoids with 5/7/6-membered ring system were isolated from the bark of Taxus chinensis var, mairei (1 and 2) and the needles of T. cuspidata (3). The structures of them were established as 2 alpha,7 beta-diacetoxy-5 alpha, 10 beta, 13 alpha, 15-tetrahydroxy-4 beta (20)-epoxy-9 alpha-benzoyloxy 11(15-->1)abeotax-11-ene (1), 2 alpha,4 alpha-diacetoxy-7 beta-benzoyloxy-5 beta,20-epox 10 beta, 13 alpha,15-tetrahydroxy-11 (15-->1)abeotax-11-ene (2), and 4 alpha, 7 beta-diacetoxy-2 alpha-benzoyloxy-5 beta,20-epoxy-9 alpha, 10 beta, 13 alpha, 15-tetrahydroxy-11(15-->1)abeotax-11-ene (3) on the basis of spectral data including 2D NMR spectroscopies.

Web of Science

researchmap

New taxane diterpenoids isolated from yew trees

Qing-Wen Shi, Hiromasa Kiyota, Takayuki Oritani

Natural Product Research and Development 11 ( 6 ) 62 - 78 1999年

Two new taxanes from Taxus chinensis var. Mairei

QW Shi, T Oritani, T Sugiyama, H Kiyota

PLANTA MEDICA 64 ( 8 ) 766 - 769 1998年12月

記述言語：英語出版者・発行元：GEORG THIEME VERLAG

Two bicyclic taxanes and two abeotaxanes were isolated from the bark and the needles of the Chinese yew, Taxus chinensis var. mairei. Thestructures of the two new compounds, 5-(N,N-dimethyl-3'-phenylisoseryl)taxachitriene A and 13-acetyl-9-deacetyl-9-benzoyl-10-debenzoyltaxchinin A, were established by spectral methods.

DOI： 10.1055/s-2006-957580

Web of Science

researchmap

Three novel bicyclic 3,8-secotaxane diterpenoids from the needles of the Chinese yew, Taxus chinensis var. mairei

QW Shi, T Oritani, T Sugiyama, H Kiyota

JOURNAL OF NATURAL PRODUCTS 61 ( 11 ) 1437 - 1440 1998年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

Three novel (1-3) and five known bicyclic 3,8-secotaxane diterpenoids were isolated from the needles of the Chinese yew, Taxus chinensis var, mairei. The structures of the new compounds were established, respectively, as (3E,7E)-2 alpha,10 beta,13 alpha-triacetoxy-5 alpha,20-dihydroxy-3,8-11-trien-9-one (1), (3E,7E)-2 alpha, 10 beta-diacetoxy-5 alpha,13 alpha,20-trihydroxy-3,8-secotaxa-3,7,11-trien-9-one (2), and (3E,8E)-7 beta,9,10 beta,13 alpha,20-pentaacetoxy-3,8-secotaxa-3,8,11-triene-2 alpha,5 alpha-diol (2-deacetyltaxachitriene A) (3), on the basis of spectral analysis. The other five bicyclic taxane diterpenoids were determined as canadensene, 6-deacetyltaxachitriene B, taxachitriene B, taxuspine U, and taxuspine X by comparison of their physical properties and spectral data with those previously reported.

DOI： 10.1021/np980213q

Web of Science

researchmap

Isolation and Structure Elucidation of a New 11(15→1)-Abeotaxane from the Chinese Yew, Taxus mairei

Qing-Wen Shi, Takayuki Oritani, Hiromasa Kiyota, Tohru Horiguchi

Natural Product Letters 12 ( 1 ) 67 - 74 1998年

　前のページ - 次のページ　

<清田 洋正>

論文 - 清田 洋正

<清田　洋正>

論文 - 清田　洋正