著者

川松 豊 杉原 弘貞 佐々木 希吉 森本 浩

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.13, pp.99-106, 1969

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I. Synthesis of 2,3-dialkoxy-5-alkyl-1,4-benzoquinone a) 4a and 4b obtained from 1 were oxidized with organic peracids to give 2,3-dimethoxy-(5a) and 2,3-diethoxy-5-methyl-1,4-benzoquinone (5b). b) 9a and 9b obtained from 6 were oxidized in a similar manner to give 5a and 10. II. Synthesis of isoprenoid quinones The authors found two new condensation methods. a) Method using an N-sulfinylamine. A solution of hydroquinone (12), methyl N-sulfinylanthranilate (14) and phytol (13) in dioxane was heated and oxidized with ferric chloride to give 2,3-dimethoxy-5-methyl-6-phytyl-1,4-benzoquinone (15) as well as by-products 16 and 17. The structures of 16 and 17 were made clear and the reaction mechanism was discussed. The results are shown in Table 1. b) Method using a metal. A solution of 5a and X-CH_2-CH=C-CH_3-CH_2-R in petroleum ether was treated with slightly an excess amount of amalgamated zinc at the room temperature to give 18. The product 18 was obtained also from hydroquinone (12). The reaction mechanism and the results are shown in Table 2. III. Stereochemistry of isoprenoid quinones It has been so far known that the steric configuration of the side chain of naturally occurring isoprenoid quinones is all-trans, but synthesized isoprenoid quinones inevitably contain a small amount of the cis-isomer. Then, the authors separated these isomers by the column chromatography to confirm their yields and to compare their NMR spectra with each other. The relationship between the structures of the quinones and the biological activity is also mentioned.

著者

武藤 毅 近藤 隆史 柴田 拓伸 曽根 大紀 藤田 達也 桐生 稔 木越 英夫 小鹿 一 山田 靜之

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.37, pp.230-235, 1995

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Constituents of the Japanese sea hare Dolabella auricularia collected in Mie Prefecture, Japan were examined by using bioassay, and new cytotoxic depsipeptides, dolastatins G (1) and H (14) and isodolastatin H (15) were isolated. Dolastatin G (1) showed cytotoxicity against HeLa-S_3 cells with an IC_<50> of 1.0μg/mL. On the basis of 2D NMR technique, dolastatin G (1) has proved to be a 35-membered cyclic depsipeptide which consists of a hexapeptide and two new hydroxy acids. The absolute stereochemistry of the hexapeptide moiety was determined by the chiral HPLC analysis of amino acids obtained by acidic hydrolysis of dolastatin G (1). The absolute stereochemistry of two hydroxy acid parts was determined by the enantioselective synthesis of two corresponding fragments obtained by degradation of dolastatin G (1). For the purpose of confirming the stereostructure of dolastatin G (1), synthetic studies on dolastatin G (1) have been carried out. Three subunits, 7, 10, and 11, were synthesized, coupling of which gave seco acid 13. The synthesis of dolastatin G (1) from seco acid 13 is in progress. A 1:1 mixture of dolastatin H (14) and isodolastatin H (15) showed potent cytotoxicity against HeLa-S_3 cells with an IC_<50> of 0.00381μg/mL. On the basis of spectroscopic data, dolastatin H (14) has proved to be a linear tetrapeptide which contains two unusual amino acids and is esterified at the C-terminus by the primary hydroxyl group of 3-phenyl-1,2-propanediol. Isodolastatin H (15) is the structural isomer of dolasatin H (15), in which the tetrapeptide is esterified at the C-terminus by the secondary hydroxyl group of 3-phenyl-1,2-propanediol. The absolute stereochemistry of dolastatin H (14) and isodolastatin H (15) was unambiguously determined by the enantioselective total synthesis.

著者

武藤 毅 近藤 隆史 柴田 拓伸 曽根 大紀 藤田 達也 桐生 稔 木越 英夫 小鹿 一 山田 靜之

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.37, pp.230-235, 1995

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Constituents of the Japanese sea hare Dolabella auricularia collected in Mie Prefecture, Japan were examined by using bioassay, and new cytotoxic depsipeptides, dolastatins G (1) and H (14) and isodolastatin H (15) were isolated. Dolastatin G (1) showed cytotoxicity against HeLa-S_3 cells with an IC_<50> of 1.0μg/mL. On the basis of 2D NMR technique, dolastatin G (1) has proved to be a 35-membered cyclic depsipeptide which consists of a hexapeptide and two new hydroxy acids. The absolute stereochemistry of the hexapeptide moiety was determined by the chiral HPLC analysis of amino acids obtained by acidic hydrolysis of dolastatin G (1). The absolute stereochemistry of two hydroxy acid parts was determined by the enantioselective synthesis of two corresponding fragments obtained by degradation of dolastatin G (1). For the purpose of confirming the stereostructure of dolastatin G (1), synthetic studies on dolastatin G (1) have been carried out. Three subunits, 7, 10, and 11, were synthesized, coupling of which gave seco acid 13. The synthesis of dolastatin G (1) from seco acid 13 is in progress. A 1:1 mixture of dolastatin H (14) and isodolastatin H (15) showed potent cytotoxicity against HeLa-S_3 cells with an IC_<50> of 0.00381μg/mL. On the basis of spectroscopic data, dolastatin H (14) has proved to be a linear tetrapeptide which contains two unusual amino acids and is esterified at the C-terminus by the primary hydroxyl group of 3-phenyl-1,2-propanediol. Isodolastatin H (15) is the structural isomer of dolasatin H (15), in which the tetrapeptide is esterified at the C-terminus by the secondary hydroxyl group of 3-phenyl-1,2-propanediol. The absolute stereochemistry of dolastatin H (14) and isodolastatin H (15) was unambiguously determined by the enantioselective total synthesis.

著者

林 恭子 濱田 康正 塩入 孝之

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.33, pp.109-115, 1991

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Dolastatin 10, a potent antineoplastic substance, was isolated from an Indian Ocean sea hare, Dolabella auricularia. The absolute stereostructure of dolastatin 10, four constituents of which are unusual amino acids, was unambiguously determined by its total synthesis to be 1. Since the reported synthesis lacks stereo-selectivity, we have developed a more efficient route to dolastatin 10, a medicinally interesting peptide. Z-(S)-Dolaphenine was prepared by the Hantzsch method using Z-L-Phe-NH_2 as a starting material. (2R, 3R, 4S)-Dolaproine was prepared from Boc-(S)-prolinal (5) and N-propionyloxazolidinone 4 by the Evans aldol methodology. The unexpected threo aldol adduct 7 was produced as the major product with a small amount of the expected erythro adduct 6 when di-n-butylboron triflate was used in excess (Table 1). Stereochemistries of these aldol adducts were determined on the basis of ^1H-NMR analyses of their corresponding cyclic derivatives 18. Further investigation about this reversal of selectivity was carried out with a variety of aldehydes including amino aldehydes under the above reaction conditions (Table 2). (3R, 4S, 5S)-Dolaisoleuine, an isostatine analogue, was prepared from Boc-L-isoleucine via the β-ketoester 22, and (S)-dolavaline was prepared from L-valine according to the literature. Assembling each constituent obtained above was efficiently carried out in a stepwise manner from the C-terminal. DEPC was mainly used for the coupling, and the attachment of Boc-L-valine with the tripeptide fragment was accomplished by use of Bop-Cl. Dolastatin 10 (1) thus synthesized was identical with the natural one in every respect.

著者

林 恭子 濱田 康正 塩入 孝之

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.33, pp.109-115, 1991

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Dolastatin 10, a potent antineoplastic substance, was isolated from an Indian Ocean sea hare, Dolabella auricularia. The absolute stereostructure of dolastatin 10, four constituents of which are unusual amino acids, was unambiguously determined by its total synthesis to be 1. Since the reported synthesis lacks stereo-selectivity, we have developed a more efficient route to dolastatin 10, a medicinally interesting peptide. Z-(S)-Dolaphenine was prepared by the Hantzsch method using Z-L-Phe-NH_2 as a starting material. (2R, 3R, 4S)-Dolaproine was prepared from Boc-(S)-prolinal (5) and N-propionyloxazolidinone 4 by the Evans aldol methodology. The unexpected threo aldol adduct 7 was produced as the major product with a small amount of the expected erythro adduct 6 when di-n-butylboron triflate was used in excess (Table 1). Stereochemistries of these aldol adducts were determined on the basis of ^1H-NMR analyses of their corresponding cyclic derivatives 18. Further investigation about this reversal of selectivity was carried out with a variety of aldehydes including amino aldehydes under the above reaction conditions (Table 2). (3R, 4S, 5S)-Dolaisoleuine, an isostatine analogue, was prepared from Boc-L-isoleucine via the β-ketoester 22, and (S)-dolavaline was prepared from L-valine according to the literature. Assembling each constituent obtained above was efficiently carried out in a stepwise manner from the C-terminal. DEPC was mainly used for the coupling, and the attachment of Boc-L-valine with the tripeptide fragment was accomplished by use of Bop-Cl. Dolastatin 10 (1) thus synthesized was identical with the natural one in every respect.

著者

吉田 将人 大澤 宏祐 高木 基樹 広川 貴次 植草 義徳 加藤 晃一 新家 一男 夏目 徹 土井 隆行

出版者

天然有機化合物討論会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

no.53, pp.241-245, 2011-09-02

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Thielocin B1 (1), isolated from the fermentation broth of Thielavia terricola RF-143 in 1995, consists of five multi-substituted benzene rings, which are connected with a 2,2', 6,6'-biaryl ether and four ester linkages. Recently, it was found that 1 strongly inhibits protein-protein interactions (PPIs) of PAC3 homodimer (IC_<50>= 0.02 μM) without inhibition of other PPIs such as PAC1/PAC2 or TCF/P-catenin. Since we are interested in the mode of action mechanisms of 1, we performed total synthesis of 1, and docking studies by NMR and in silico analyses. The key intermediate 2,2', 6,6'-biaryl ether 4 was synthesized from 7-membered lactone 6, which was prepared by oxidative lactonization of benzophenone 7, followed by chemoselective reduction of the lactone and removal of the resulting alcohol. The side wing 5 was synthesized from aldehyde 8 via formation of 3 and its coupling by esterification. Condensation of biaryl ether 4 and 5 was smoothly performed using trifluoroacetic anhydride to afford 21 in high yield. Formylation of 21 by treatment with dichloromethyl methyl ether and AgOTf, followed by Kraus oxidation provided acid 2. Coupling of the resulting acid 2 with phenol 3 afforded 22 in 70% yield. Finally, removal of the benzyl groups by-hydrogenation furnished thielocin B1 (1), whose spectral data were in good agreement with those of the natural product.

著者

岡部 光 宮原 由美 山内 辰郎

出版者

天然有機化合物討論会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

no.24, pp.95-102, 1981-09-10

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An extensive survey for the triterpenoid constituents of Momordica charantia L. has been carried out in this laboratory, and so far, five glycosides (momordicosides A-E) of cucurbit-5-ene derivatives were isolated from the seeds, and their structures were determined. They are unique cucurbitacins being highly oxygenated only in the side chain and having no oxygen function at C_<11>. This study concerns the structure elucidation of two bitter glycosides, momordicosides K and L, and four non-bitter glycosides, momordicosides F_1, F_2, G and I isolated from the fruits. The structure of F_1 was proposed as 3-O-β-D-glucopyranoside of 5,19-epoxy-25-methoxy-5β-cucurbita-6,23-dien-3β-ol on the basis of PMR, CMR and CD spectral data and chemical conversion into a cucurbit-5-ene derivative. G is the corresponding β-D-allopyranoside. F_2 and I are the C_<25>-OH derivatives corresponding to G and F_1, respectively. K and L were determined as 7-O-β-D-glucopyranosides of 19-oxo-25-methoxy-cucurbita-5,23-diene-3β, 7β-diol and its C_<25>-OH derivative, respectively, on the basis of spectral data and chemical correlation with F_1-aglycone. F_1, F_2, G and I are the first cucurbitacins having 5β-cucurbitane nucleus found in nature, and K and L are noted as the new cucurbitacins having C_9-aldehyde and 7-O-β-D-glucopyranosyl groups. Among momordicosides, G and F_2 are the first triterpenoid glycosides having D-allose as a component sugar.

著者

高野 誠一 畑山 範 高橋 召 高橋 洋子 岩田 裕光 宍戸 宏造 小笠原 国郎

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.21, pp.50-57, 1978

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A new synthetic approach to the alkaloids related to emetine (3) and quinine(5) from norbornylene(1) is described. Norbornylene(1) was transformed into (±)-norcamphor(2) which was oxidized to the bicyclic lactone(8) by Baeyer-Villiger oxidation then alkylated with ethyl bromide and allyl bromide in a stereospecific fashion to give (9) and (29), respectively. The former lactone(9) was converted into the emetine precursor(21) and protoemetinol(4) both in dl form via the α-diketone monothioketal (13). The latter lactone(29) was converted into the homomeroquinene equivalent(37) via the α-diketone monothioketal(32) which was then transformed into dl-meroquinene aldehyde(6) via the olefin formation through the phenylselenide(41). Since norbornylene(1) has been converted into a chiral norcamphor(2), the present method would be applicable to the synthesis of the above alkaloids together with various indole alkaloids in a chiral form.

著者

志津里 芳一 山口 修 松永 公浩 玉木 和彦 山村 庄亮 寺田 幸正

出版者

天然有機化合物討論会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

no.29, pp.333-340, 1987-07-25

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Two sex pheromones of the American cockroach, periplanone A and B, have been isolated by Persoons et al. The structure of the latter was proposed by the same authors, and then its stereostructure including the absolute configuration was unambiguously determined by its synthesis. Furthermore, the structure (1) of periplanone A has been proposed by Persoons et al., on the basis of its spectral data together with some chemical evidence, but the stereochemistry was not known. In order to elucidate the structure of periplanone A, the authors have synthesized two possible hydroazulenones (5 and 6) from germacrene-D by using biomimetic transannular reactions as a key step. However, the spectral data of synthetic compounds were entirely different from those of natural one. Therefore, the ^1H NMR and IR spectral data of periplanone A and its rearrangement product were reexamined, consequently, the structures of both compounds were found to be resembled each other. Clearly, the structure of periplanone A, which is quite labile as compared with the rearrangement product, seems to be represented by one of the possible decalones (I or II), while the latter must be depicted by III or IV. As shown in Table 1 and 2, the coupling constants based on the conformations I and III, obtained from molecular mechanics calculations, were compatible with the observed ones for periplanone A and rearrangement product, respectively. Thus, the stereostructure of periplanone A was elucidated as I.

著者

丹羽 正武 寺田 幸正 井口 正信 山村 庄亮

出版者

天然有機化合物討論会

雑誌

天然有機化合物討論会講演要旨集

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no.23, pp.96-103, 1980-09-10

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From a biogenetic point of view, many sesquiterpenes are considered to be derived from germacrenes or germacrones as an important precurser, and their conformations have been discussed in connection with their transannular reactions as well as with thermal isomeizations. Thus, molecular mechanics calculations were successfully carried out to evaluate relative stabilities of each conformation of several germacrenes in their ground states and transition states. Particularly, molecular mechanics calculation was carried out successfully in the case of thermal reaction of acoragermacrone, and also attempted for the acid-catalyzed reaction of preisocalamendiol leading to the formation of isocalamendiol, although the result so far obtained was not necessarily satisfied. On the basis of the above results, acid and base-catalyzed reactions of epoxygermacrene-D were carried out to give many interesting compounds similar to oppositol, axisonitrile-1, periplanone-A, junenol and so on. Reaction process of these compounds is also presented.

著者

末宗 洋 上野 貢嗣 川原 哲也 小田 晃造 舟越 和久 酒井 浄

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.27, pp.108-114, 1985

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In the synthesis of natural products consisting of the basic structure of cyclopentane ring, variously functionalized cyclopentanones are required as starting materials. Previously, we succeeded in a simple, highly stereospecific synthesis of the cis-3,4-disubstituted cyclopentanones by the mild reaction with RhCl(PPh_3)_3. By the application of this newer cyclization reaction, we have succeeded in the synthesis of cis,cis-dihydronepetalactone, prostanoic acid, 8-isoprostanoic acid, (+)-brefeldin A and carbacyclin in the optically active form from limonene or Corey lactone. These compounds were synthesized via the following key steps. 1) 3-(3-Oxobutyl)cyclopentanone was easily converted to the deconjugated bicyclic enone (3→4). 2) The regioselective alkylation of limonene was performed by using s-BuLi-TMEDA (1→8). 3) The cis-3,4-disubstituted cyclopentanone from limonen-10-ol could be converted to the trans-3,4-disubstituted cyclo-pentanone by the epimerization (15→16, 22→23).

著者

飯島 崇士 毛利 圭宏 提箸 正義 山田 大士 服部 恭尚 濱渦 康範 加茂 綱嗣 廣田 満 清田 洋正 真壁 秀文

出版者

天然有機化合物討論会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

no.51, pp.289-294, 2009-09-01

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1. Synthesis of procyanidin B1-B4(1-4). Stereoselective synthesis of catechin and epocatechin under intermolecular condensation of equimolar amount of catechin derivatives catalyzed by Yb(OTf)_3. The coupled products were successfully converted to procyanidin B1 (1), B2 (2), B3 (3), and B4 (4), respectively. 2. synthetic of (-)-epicatechin 3-(3"-O-methylgallate) (13) and (+)-catechin 3-(3"-O-methylgallate) (14) A concise synthesis of (-)-epicatechin 3-(3"-O-methylgallate)(13, ECG3"Me), which is a minor constituent of tea, and (+)-catechin 3-(3"-O-methylgallate)(14, CG3"Me) via condensation of equimolar amount of catechin and gallate derivatives has been achieved. The anti-inflammatory effect of the synthetic compounds on TPA-induced inflammation of mouse ears was examined. Compounds 13 and 14 suppressed the TPA-induced inflammation of mouse ears by 50% and 43%, respectively, at a dose of 200μg. 3. Short step synthesis of resveratrol derivative. An efficient synthesis of trimethoxylated resveratrol (20) is presented using advanced Heck reaction promoted by Pd(dba)_2 in the presence of P(t-Bu)_3.

著者

井原 正隆 川口 明洋 加藤木 守 千尋 正利 福本 圭一郎 亀谷 哲治

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.28, pp.339-346, 1986

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Synthesis of angularly tricyclopentanoid sesquiterpenes, was investigated via tricyclo[7.3.0.0^<1,5>]dodecane derivatives using intramolecular Diels-Alder reaction or intramolecular double Michael reaction as a key step. (1) Highly Stereoselective Total Synthesis of (±)-3-Oxosilphinene via Intramolecular Diels-Alder Reaction-(E,E)-3-(8-Phenylthio-octa-5,7-dien-2-yl)-2-methyl-2-cyclopenten-1-one (19) was prepared from the bromocyclopentenone (16) in three steps. Cycloaddition of 19 gave only one stereoisomer of the tricyclo[7.3.0.0^<1,5>]dodecene (20) having all correct four contiguous asymmetric centers. The cyclo-adduct (20) was converted into the tricyclo[6.3.0.0^<4,8>]undecane (25) via Wolff rearrangement. According to usual procedures, the ester (25) was then transformed into (±)-3-oxosilphinene (1). (2) Synthetic Study of Pentalenene and Pentalenic Acid via Intramolecular Double Michael Reaction-Barbier reaction of 4,4-dimethyl-2-cyclopenten-1-one (34) followed by oxidation with pyridinium chlorochromate gave the enone (36), which was converted into the bis-enone (33) in four steps. Intramolecular double Michael reaction of 33, carried out by heating with trimethylsilyl chloride, triethylamine, and zinc chloride, gave tricyclo[7.3.0.0^<1,5>]dodecanediones (40), which were subjected to Wolff rearrangement to afford the tricyclo[6.3.0.0^<4,8>]undecanes (41) possessing all carbon skeleton of natural products (4 and 5).

著者

工藤 雄大 此木 敬一 長 由扶子 安元 健 山下 まり

出版者

天然有機化合物討論会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

no.53, pp.367-372, 2011-09-02

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Tetrodotoxin (TTX) is distributed in wide range of animals, marine puffer fish and terrestrial newts and frogs, for examples. We have isolated various TTX analogs from these animals, and attempted to obtain clues to biosynthetic pathway of TTX from the structures of these analogs. Here we isolated four new analogs of TTX from the Okinawan newt Cynops ensicauda popei, and determined their structures as 8-epi-5,6,11-trideoxyTTX, its 4,9-anhydro derivative, its 1-hydroxy derivative, and its 1-hydroxy-4,4a-anhydro derivative, by spectroscopic method. These analogs are not detected in puffer fish, instead, 5,6,11-trideoxyTTX is detected as a major analog in puffer fish eggs. 1-Hydroxy type analog might be specific to newts, since 1-hydroxy-5,11-dideoxyTTX was previously isolated from the other species of newt, Taricha granulosa, by other group. This is the first identification of 4,4a-anhydro type analog of TTX from the natural source.

著者

伊藤 大輔 新海 陽介 三木 直子 加藤 友紀 近藤 忠雄 吉田 久美

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.49, pp.455-460, 2007

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The sepals of Hydrangea macrophylla show various colors from red through purple to blue and famous for its easy color change. However, any colored sepals consisted of the same components; one anthocyanin, delphinidin 3-glucoside (1) and three co-pigments, 5-O-caffeoylquinic acid (neochlorogenic acid, 2), 5-O-p-coumaroylquinic acid (3) and 3-O-caffeoylquinic acid (chlorogenic acid, 4). For blue color development, Al^<3+> has been clarified to be essential and we obtained stable blue solution by mixing 1, 2 and Al^<3+>. However the mechanism of flower color variation and the chemical structure of the blue pigment are still obscure. To clarify the color variation of hydrangea, we established "Single Cell Analysis Method". After recording the absorption spectrum of a cell, the vacuolar pH of the cell was measured by using a microelectrode. By micro-HPLC technique, the composition of 1-4 and Al^<3+> was determined. Combining the results, we could reproduce the cell color from blue to red by mixing the components in various pH aq. solutions.

著者

竹元 万寿美 山本 裕一 阿知波 一雄 Kutney James P. Stoynov Nikolay M.

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.38, pp.643-648, 1996

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In recent years, much attention has been paid to the ability of cultured plant cells to transform not only secondary metabolites, but also organic foreign substrates. Therefore, we have studied in the feasibility of using plant cell cultures as the reagents of organic synthesis. In this symposium, we report the synthesis of biologically active com-pounds by using plant cell cultures (N. tabacum, D. carota, C. roseus, P. peltatum) as follows (1) Synthesis of optically active α-phenylpyridylmethanols as organic foreign substrates i) enantioselective reduction of ketone ii) asymmetric hydrolysis of the acetates iii) optically active alcohols production from the corresponding racemates (deracemization of racemates) (2) The efficient synthesis of podophyllotoxin derivatives as starting materials in the clinical anti-cancer drug, Etoposide

著者

石塚 みどり 田中 俊之 福田 純子 平間 正博 大谷 敏夫

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.42, pp.331-336, 2000

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C-1027 is a potent antitumor antibiotic, in which a nonprotein chromophore is tightly and specifically bound to an apoprotein. The chromophore, which has an endiyne structure and is responsible for DNA cleavage, is very labile when isolated, but greatly stabilized through binding to the apoprotein. Their binding structure and stabilizing interactions are very interesting problems in terms of molecular recognition and protein transport. The 3D structure of C-1027 apoprotein was determined by the X-PLOR calculation using 1539 experimental restrains derived from NMR spectroscopy. The apoprotein has three antiparallel β-sheets, and the hydrophobic pocket is formed by four-stranded β-sheet (DCHI) and two loops (residues 75-79, 97-100)(Fig.3). The overall shape of the apoprotein is quite similar to those of neocarzinostatin (NCS) and actinoxanthin (AXN). The binding structure of C-1027 complex was calculated based on 1539 NMR-derived constraints which include 38 intermolecular restraints between the aromatized chromophore and the apoprotein. The aromatized chromophore is bound to the hydrophobic pocket of the apoprotein. The benzodihydropentalene core locates in the center of the pocket with its molecular plane almost perpendicular to the bottom of the pocket. The β-tyrosine unit locates on the left side of the core, and both benzoxazine and aminosugar moieties on the right side (Fig.4). The hydrophobic interaction is most likely the major binding interaction between the apoprotein and the aromatized chromophore. Moreover, the 18-amino group of the chromophore locates in the proximity of either the carboxylate of Asp101 or the imidazole ring of His104, which indicates there could be a salt-bridge or a hydrogen bond type interaction between the aromatized chromophore and these side chains. To confirm the predicted binding interactions, we made several mutant apoproteins whose specific amino acid residue is replaced with the amino acid of different type and examined their binding abilities for the aromatized chromophore by NMR. The results obtained will be discussed.

著者

臼杵 豊展 井上 将行 平間 正博 田中 俊之 細井 文仁 大家 真治 大谷 敏夫

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.45, pp.257-262, 2003

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The antitumor antibiotic C-1027 is a 1:1 complex of a highly labile enediyne chromophore (1) and a carrier apoprotein. C-1027 exhibited the potent cytotoxicity toward various cancer cells. The p-benzyne biradical (2), which is in equilibrium with 1, abstracts hydrogens from DNA to exert its biological activity. The apoprotein functions as both the stabilizer and the drug delivery system of 1. Recently, we found that the biradical 2 slowly abstracts α-proton of Gly96 of the apoprotein, which caused the oxidative cleavage of the peptides and led to a self-degradation of C-1027. To create a more stable analog of antibiotic C-1027, we designed a Gly96-deuterated (D-Gly) apoprotein. The D-Gly apoprotein was expressed in Escherichia coli in the presence of glycine-d_5. The unstable chromophore 1, isolated from natural C-1027, was then incorporated into the D-Gly apoprotein using HPLC techniques to obtain the D-Gly C-1027. Stability tests revealed that the D-Gly C-1027 was 1.8 and 4.9 times as stable as the natural one under solid and solution states, respectively. Cytotoxicity test also reflected the stability of D-Gly C-1027. Thus, we achieved the creation of supranatural products by rational design utilizing kinetic isotope effect. The presented work demonstrated the novel design principle to create the supra-natural products by integrating the data of physicochemical property of the small molecule and the atomic-level 3D-structure of the protein, which will be applicable to other biologically important natural products and proteins.

著者

吉田 健一郎 東 龍太郎 佐伯 真由子 南 慶典 大谷 敏夫

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.35, pp.250-257, 1993

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Antibiotic C-1027, a novel antitumor chromoprotein isolated from the broth filtrate of Streptomyces globisporus C-1027, shows extremely potent cytotoxicity against KB carcinoma cells (IC_<50> 0.1ng/ml) in vitro and antitumor activity toward tumor-bearing mice in vivo. These activities are correlated with the ability of the antibiotic to cause DNA double-strand scission. The antibiotic consists of an apoprotein and a labile chromophore (C-1027-Chr) that is responsible for the biological activity of C-1027. The chromophore is readily separated from its apo-protein by extraction, but the exceeding instability in the protein-free state hampered the structure elucidation. The similar situation has been also observed in the other chromoprotein antibiotics of this family such as neocarzinostatin (NCS), macromomycin, auromomycin (AUR), actinoxanthin and kedarcidin. Among them, NCS is the only one whose chromophore structure has been elucidated, and very recently, the structural novelty of kedarcidin chromophore has been disclosed by the Bristol-Myers Squibb group. We have characterized an inactive but more stable reaction product (2) of C-1027-Chr, which was prepared by treatment of C-1027-Chr in ethanol. It possesses a macrocyclic structure together with oxazolinate and aminosugar moieties as side chains. Its benzodihydropentalene core structure suggested to us the presence of an enediyne in the native C-1027-Chr. We disclose herein the novel structure of C-1027-Chr (1) and the cycloaromatization mechanism leading to product (2), which would explain its extreme potency in terms of cytotoxicity and ability to cause DNA double-strand scission.

著者

寺原 昭 羽石 達生 新井 守 桑野 晴光

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.18, pp.286-293, 1974

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The antifungal metabolite, herbicidin A (C_<23>H_<29>O_<11>N_5) and herbicidin B (C_<18>H_<23>O_9N_5) obtained from Streptmyces saganonensis (Strain No 4075) have a plant growth inhibiting effects against to baryard glass, green panicum, tomato and radish ect., in a concentration 37-300ppm without effect to rice. Basic hydrolysis of herbicidin A affords an unsaturated acid 3 which has been confirmed to be 2-hydroxymethyl-2-butenoic acid, and herbicidin B acid 4. Methanolysis of herbicidin A and B with Amberlyst 15 in methanol affords adenine, and C_<19>H_<28>O_<12> 8 and C_<15>H_<24>O_<10> 5 respectively. On the bases of chemical and physico-chemical evidences of these derivatives, structures of herbicidin A and B have been determined to be nucleosides which consist of adenine and an unusual sugar moiety.