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Matsutaka HIGA, Kazuhito OGIHARA, Seiichi YOGI
1998 年 46 巻 8 号 p.
1189-1193
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
From the fresh fruits of Diospyros maritima BLUME (Ebenaceae) three new naphthoquinones, 3-bromoplumbagin (1), ethylidene-6, 6'-biplumbagin (2), and 3-(2-hydroxyethyl)plumbagin (3), were isolated, in addition to six known naphthoquinones, 3-chloroplumbagin (4), 3-methylplumbagin (5), plumbagin (6), droserone (7), elliptinone (8), and maritinone (9). The structures of the new compounds were established by chemical and spectroscopic means.The 21 compounds isolated from this plant were examined for ichthyotoxic activity, germination inhibitory activity, and antifugal activity. The naphthoquinone derivatives from the fruits of Diospyros maritima showed a variety of biological activities, especially plumbagin (6), which showed strong activity in these three bioassays.
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Hiroyuki MINAMI, Sayoko ANZAKI, Miwa KUBO, Mitsuaki KODAMA, Kazuyoshi ...
1998 年 46 巻 8 号 p.
1194-1198
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Five new vibsane-type diterpenes, vibsanin G, vibsanin H, vibsanin K, 18-O-methylvibsanin K and 15, 18-di-O-methylvibsanin H were isoalted from the leaves of Viburnum awabuki (Caplifoliaceae). Their structures were elucidated by analyses of spectroscopic data involving comparison of their
13C-NMR data with those of the previously known vibsanin C, and the structure of vibsanins H and K were confirmed by X-ray crystallographic analysis and chemcial transformation, respectively. All five new compounds differ from the seven-membered ring vibsane-type diterpene, vibsanin C, only in the C-12-C-17 side chain.
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Kiyoshi HORITA, Masaaki NAGASAWA, Youji SAKURAI, Osamu YONEMITSU
1998 年 46 巻 8 号 p.
1199-1216
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
The C16-C36 unit of halichondrin B was stereoselectively synthesized via the aldol condensation of two C16-C26 esters with the previously synthesized C27-C36 aldehyde followed by E ring construction. The C16-C26 esters were prepared starting from (2S)-3-hydroxy-2-methylpropionic acid and L-tartaric acid via construction of the D ring by iodoetherification.
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Kazuhiro KONDO, Yasuoki MURAKAMI
1998 年 46 巻 8 号 p.
1217-1219
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Highly selective benzoylation of a less hindered amino group in the presence of a more hindered amino group with 2-chloro-N, N-dibenzoylaniline (2d), a convenient to use and stable reagent, is described.
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Taisuke ITAYA, Tae KANAI
1998 年 46 巻 8 号 p.
1220-1224
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
An improved synthesis of the key intermediates (3 and 8) for the synthesis of β-hydroxywybutines [[R-(R
*, S
*)]- and [S-(R
*, R
*)]-4], the most probable structures for the minor base from rat liver tRNA
Phe, has been achieved by the Witting reaction between 1-benzyl-7-formylwye (1) and the phosphorane derived from (R)-2-[(methoxycarbonyl)amino]-3-(triphenylphosphonio)propanoate (10), followed by methylation, OsO
4 oxidation, and cyclocondensation with COCl
2 in the presence of pyridine. The racemic forms of β-hydroxywybutines [(R
*, S
*)- and (R
*, R
*)-4], which were required for the determination of the optical purity of [R-(R
*, S
*)]- and [S-(R
*, R
*)]-4 by means of chiral HPLC, were conveniently prepared through pyrolysis of the cyclic carbonate 3 followed by NaBH
4 reduction and catalytic hydrogenolysis. The samples of [R-(R
*, S
*)]- and [S-(R
*, R
*)]-4 were thus shown to be optically pure.
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Fumiyuki KIUCHI, Noriko SUZUKI, Yumiko FUKUMOTO, Yoshihisa GOTO, Marik ...
1998 年 46 巻 8 号 p.
1225-1228
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Embelin, a major constituent of Embelia ribes BURM. (Myrsinaceae) was transformed into different types of compounds through dimerization during preparation of a decoction. Two of the products are proposed to have furanylidene benzofuranone and 1, 4-dibenzofurandione skeletons on the basis of spectroscopic means. The transformation of embelin in boiling water is markedly accelerated by the presence of fatty acids.
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Fumiyuki KIUCHI, Hiromi TAKASHIMA, Yoshisuke TSUDA
1998 年 46 巻 8 号 p.
1229-1234
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
2, 5-Dihydroxybenzoquinones, when heated in water, react to form different types of compounds through dimerization. The features of this unique reaction were clarified using a model compound, 2, 5-dihydroxy-3-methyl-benzoquinone. The structures of the products were established by X-ray analysis and spectroscopic means.
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Fumiko ABE, Tatsuo YAMAUCHI, Hirotaka SHIBUYA, Isao KITAGAWA, Masami Y ...
1998 年 46 巻 8 号 p.
1235-1238
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Seventeen alkaloids were isolated from the air-dried leaves of Alstonia villosa and their structures characterized. One of the seven new alkaloids was elucidated to be (19Z)-5α-methoxyrhazimine, having a 3, 4-dihydroquinoline nucleus.
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Kazuko YOSHIKAWA, Koji MATSUCHIKA, Shigenobu ARIHARA, Hsen-Chang CHANG ...
1998 年 46 巻 8 号 p.
1239-1243
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
The structural elucidation of six new related polyoxypregnane glycosides, gymnepregosides A (1), B (2), C (3), D (4), E (5) and F (6), together with two known compounds, from the roots of Gymnema alternifolium (Asclepiadaceae) was achieved through on a detailed study of
1H- and <13>C-NMR spectral data and chemical means. The results obtained for new compounds, 1-6, show that they are (20S)-pregn-6-ene-3β, 5α, 8β, 12β, 14β, 17β, 20-heptaol or sarcostin 3-O-glycosides, and all the sugars at C-3 are β(1→4)-linked. Some of them possessed benzoyl, cinnamoyl and tigloyl residues as the ester linkages located at C-12 and/or C-20 of the aglycon.
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Hironori FURUKAWA, Kazunori KOIDE, Ken-ichi TAKAO, Susumu KOBAYASHI
1998 年 46 巻 8 号 p.
1244-1247
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Glycosylation reactions using a glycosyl 2-pyridinecarboxylate as a glycosyl donor were performed. Glycosyl 2-pyridinecarboxylate was designed based on a variation of the Remote Activation Concept and is activated through bidentate coordination to mild Lewis acids such as copper triflate and tin triflate. This method was effective for the glycosidation of not only glucose, but several other sugars such as the mannose-type, 2-azidosugar-type, and 2-deoxysugar-type. Various disaccharides were obtained in excellent yield by this reaction.
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Kazunori ODASHIMA, Takashi ITO, Koji TOHDA, Yoshio UMEZAWA
1998 年 46 巻 8 号 p.
1248-1253
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Complexation of quaternary ammonium salts (Q
+X
-) and undissociated, neutral phenols (ArOH) in homogeneous organic solutions was systematically investigated to afford a reliable quantitative basis for a new model of anionic potentiometric response to neutral phenols, displayed by organic liquid membranes based on Q
+X
-. IR,
1H- and
13C-NMR, and UV studies indicated complexation of Q
+X
- and ArOH in 1 : 1 stoichiometry in nonpolar organic solvents such as benzene and chloroform. The stability constant (K
s) of the complex was affected by the acidity and lipophilicity of the ArOH component as well as the size of X
- of the Q
+X
- component; stronger complexes were formed by ArOH with a lower pK
a and higher log P
oct, as well as by Q
+X
- with a smaller ionic radius for X
-. These results suggest that the major driving force for complexation is hydrogen bonding interactions between X
- and the phenolic OH. The K
s values were found to be parallel with the magnitudes of anionic potentiometric responses by membranes based on Q
+X
-, indicating that the complexation of ArOH by Q
+X
- plays an important role in the anionic potentiometric responses. The significance of proton dissociation from the Q
+X
-·ArOH complex was also discussed.
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Dhananjaya NAUDURI, Gopu Bala Show REDDY
1998 年 46 巻 8 号 p.
1254-1260
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
A series of 3-styryl-1, 5-diphenyl and 5-styryl-1, 3-diphenyl 2-pyrazolines of different substitutions has been synthesized by condensation of substituted α, β-unsaturated ketones with phenylhydrazine hydrochloride in presence of catalytic amount of concentrated HCl. Compounds in the 3-styryl series had OMe, NMe
2, NO
2, OH and isopropyl substituents and those in the 5-styryl series had OMe, NMe
2 and NO
s. The 3-styryl-1, 5-diphenyl compounds showed little variation in antibacterial activity towards gram-positive and gram-negative bacteria in terms of geometric mean minimum inhibitory concentrations (MIC). The 4', 4''-NMe
2, 4', 4''-NO
2 and 4', 4''-OMe compounds were found to possess the highest activity in the series. The 5-styryl-1, 3-diphenyl series showed lower activities than the 3-styryl series. The in vitro antimycotic activity of the 4', 4''-OH and 2', 2''-OH substituted compounds showed good activity than the other molecules in the two series.
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Jun YANAGIDA, Rinako MATSUHASHI, Ie WATANABE, Tadaaki SATOU, Kazuo KOI ...
1998 年 46 巻 8 号 p.
1261-1264
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
A new subculture method and a novel microplate assay for nematocidal activity using a species of Diplogastridae have been developed. The assay gives results rapidly, with high sensitivity in 4h, and indicated good correlation between action mechanism and the nematode shape when examining 15 known compounds, including the antiparasitic avermectin, antimalarial quinine, and the γ-amino-n-butyric acid
A (GABA
A) activated Cl
- channel antagonist picrotoxinin. Thus new assay could be used as a primary screening method for new nematocidal compounds.
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Tomoo SUZUKI, Toshinao USUI, Mitsuru OKA, Tsunemasa SUZUKI, Tadashi KA ...
1998 年 46 巻 8 号 p.
1265-1273
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
In order to discover a medicine effective against Alzheimer's disease, we synthesized a series of quinoline derivatives having a characteristic 1-azabicyclo[3.3.0]octane amine ring, and performed pharmacological evaluation of them. Acetylcholine esterase inhibitory activities of these derivatives were unexpectedly weak. Tests for central nervous muscarinic cholinergic receptor binding affinity indicated that these compounds had higher affinities to muscarinic M1 receptors than to M2 receptors.A series of naphthalene derivatives substituted with the 1-azabicyclo[3.3.0]octane ring were also synthesized and muscarinic M1 and M2 receptor binding affinity deterimned. These compounds had much higher affinity for M1 receptors than the quinoline derivatives, and 1-[N-(1-azabicyclo[3.3.0]octan-5-yl)methyl-N-methylamino]-4-nitronaphthalene showed the highest affinity and selectivity. The ability of this compound to improve cognitive function was assessed using the passive avoidance test in scopolamine-induced mice.
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Ryo NAITO, Makoto TAKEUCHI, Koichiro MORIHIRA, Masahiko HAYAKAWA, Ken ...
1998 年 46 巻 8 号 p.
1274-1285
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
A series of 1-substituetd-4-piperidyl benzhydrylcarbamate derivatives were synthesized and evaluated for binding affinity to M
1, M
2 and M
3 receptors, and for antimuscarinic activities. Receptor binding assays indicated that 1-benzyl-4-piperidyl benzhydrylcarbamate derivatives showed higher affinities for M
1 and M
3 receptors, and good selectivities for M
3 over M
2 receptor, than the corresponding ester analog. These results indicate that the urethane bond is a novel linker for muscarinic antagonists, and serves to lock the molecular conformation and allows the hydrophobic portion and cationic site of the molecule to bind to M
1 and M
3 muscarinic receptors. Among the prepared compounds, 1-(4-methylaminobenzyl)-4-piperidyl benzhydrylcarbamate monohydrochloride (18b, YM-58790) exhibited potent inhibitory activity on bladder pressure in reflexly-evoked rhythmic contraction, comparable to oxybutynin and was approximately ten times less inhibitory on oxotremorine-induced salivary secretion than oxybutynin in rats. Further evaluation of antimuscarinic effects on bradycardia and pressor in pithed rats, and on tremor in mice, demonstrate that YM-58790 can be useful for treatment of urinary urge incontinence as a bladder-selective M
3 antagonist with fewer side effects.
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Ryo NAITO, Makoto TAKEUCHI, Koichiro MORIHIRA, Masahiko HAYAKAWA, Ken ...
1998 年 46 巻 8 号 p.
1286-1294
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
A novel series of biphenylylcarbamate derivaties were synthesized and evaluated for binding to M
1, M
2 and M
3 receptors and for antimuscarinic activities. Receptor binding assays indicated that biphenyl-2-ylcarbamate derivatives had high affinities for M
1 and M
3 receptors and good selectivities for M
3 receptor over M
2 receptor, indicating that the biphenyl-2-yl group is a novel hydrophobic replacement for the benzhydryl group in the muscarinic antagonist field. In this series, quinuclidin-4-yl biphenyl-2-ylcarbamate monohydrochloride (81, YM-46303) exhibited the highest affinities for M
1 and M
3 receptors, and selectivity for M
3 over M
2 receptor. Compared to oxybutynin, YM-46303 showed approximately ten times higher inhibitory activity on bladder pressure in reflexly-evoked rhythimic contration, and about 5-fold greater selectivity for urinary bladder contraction against salivary secretion in rats. Moreover, selective antagonistic activity was also observed in vitro. Further evaluation of antimuscarinic effects on bradycardia and pressor in pithed rats, and on tremor in mice, showed that YM-46303 can be useful for the treatment of urinary urge incontinence as a bladder-selective M
3 antagonist with potent activities and fewer side effects.
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Koichi MACHIDA, Rie ONODERA, Kyoko FURUTA, Masao KIKUCHI
1998 年 46 巻 8 号 p.
1295-1300
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Nine new monoterpenoids, gardenamide (1), 6α-butoxygeniposide (2), 6β-butoxygeniposide (3), 6''-O-p-cis-coumaroylgenipin gentiobioside (4), and jasminosides A (6), B (7), C (8), D (9), E (10), were isolated from Gardeniae Fructus. Their structures were established on the basis of spectral analysis.
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Tian-Shung WU, Yann-Lii LEU, Yu-Yi CHAN
1998 年 46 巻 8 号 p.
1301-1302
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Seven denitroaristolochic acids, incuding four new compounds, sodium aristofolin-A, aristofolin-B-D and three known compounds, aristofolin-A, aristolic acid and methyl aristolate were isolated from the leaves of Aristolochia cucurbitifolia. Their structures were determined by spectroscopic methods.
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Takashi ISHIZU, Shunsaku NOGUCHI
1998 年 46 巻 8 号 p.
1303-1307
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Cyclo(Phe-Pro)
4 (1) formed a 1 : 1 complex with noradrenaline hydrochloride (NAd·HCl) through intermolecular hydrogen bonds and a hydrophobic effects. The formation constant of the 1 : 1 complex of 1 with l-Nad·HCl was approximately 12.3 times that of the complex with d-Nad·HCl. It was presumed that the secondary hydroxy group of l-NAd·HCl formed an intermolecular hydrogen bond with Pro
1 CO of 1, whereas that of d-NAd·HCl did not. The 1 : 1 complexes of 1 with various amine hydrochlorides were prepared.
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Tokujiro KITAGAWA, Chinatsu TSUTSUI
1998 年 46 巻 8 号 p.
1308-1310
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
N'-Chlorophenyl- and N'-chlorobenzyl-N-furfuryloxamides (6b-e and 7b-d) were synthesized through the reaction of chloro-substituted anilines (12b-e) or chloro-substituted benzylamines (13b-d) with N-furfuryloxamic acid sodium salt (10), which was prepared via condensation of methyl oxalate (8) with furfurylamine, followed by hydrolysis of the resulting amide-ester with sodium hydroxide. The activity of the prepared compounds (6 and 7) as plant growth regulators was examined by a germination assay using rape and leek seeds.N'-(3-Chlorophenyl)-N-furfuryloxamide (6c) showed a little effectiveness as an inhibitor, whereas the parent compound, N'-phenyl-N-furfuryloxamide (6a) inhibited the root growth of rape seedlings. The 2-chlorophenyl derivative (6b) inhibited the root growth of rape seedlings as potently as 6a, but sufficiently promoted the root growth of leek seedlings. Further, the 4-chlorophenyl derivative (6d) promoted the root growth of both species. On the other hand, in the series of chlorinated benzyl derivatives (7b-d), N'-(3-chlorobenzyl)-N-furfuryloxamide (7c) showed a markedly superior inhibitory effect in both species, but 2- and 4-chlorobenzyl derivatives (7b and 7d) inhibited the root growth of only rape seedlings.
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Hitoshi ABE, Akira YAMASAKI, Takashi HARAYAMA
1998 年 46 巻 8 号 p.
1311-1313
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
A new reagent system, phenyl trimethylsilyl selenide-aluminum bromide, was developed for the direct conversion of various benzylic hydroxy groups into a selenenyl group. Treatment of cinnamyl alcohol with this reagent system yielded 3, 4-dihydro-4-phenyl-2H-1-benzoselenin via a [3, 3]-sigmatropic rearrangement of the intermediate cinnamyl phenyl selenide.
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Hikokazu SUZUKI, Magoichi SAKO, Kosaku HIROTA
1998 年 46 巻 8 号 p.
1314-1316
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Thermolysis of taxinine and taxinine H, esters of 2α, 9α, 10β-triacetoxy-8β, 12, 15α, 15β-tetramethyl-4-methylene-13-oxotricyclo[9.3.1.0
3, 8] pentadec-11-en-5α-ol, resulted in the smooth formation of the corresponding 4-en-4-ylmethanol esters and the 4(20), 5-diene by virtue of migration and elimination of the 5-O-ester moiety, thus providing useful methods for chemical modifications of the C-ring in taxinine derivatives.
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Takeshi YAMAMOTO, Manabu HORI, Ikuo WATANABE, Hisayoshi TSUTSUI, Shoji ...
1998 年 46 巻 8 号 p.
1317-1320
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
N-Isopropylation of methyl 2, 2-dimethyl-3-oxo-3, 4-dihydro-2H-benzo[1, 4]oxazine-6-carboxylate (2a) with various reagents was examined in order to prepare 3a, the key intermediate in the synthesis of N-(4-isopropyl-2, 2-dimethyl-3-oxo-3, 4-dihydro-2H-benzo[1, 4]oxazine-6-carbonyl)guanidine methanesulfonate (1, KB-R9032), a novel, potent Na/H exchange inhibitor. When a base such as sodium hydride, potassium carbonate or potassium tert-butoxide was used, the undesired O-isopropyl derivative 4a was produced as the main product. Among the hydrogen bond assisted mild bases examined, potassium fluoride (KF)-alumina afforded the best N-/O-selectivity with a ratio of about four. The undersired O-isopropyl derivative 4a could be easily converted to the starting 2a under non-aqueous acidic conditions. Combination of the above two processes increased the N-/O-ratio (to about 42). Consequently, the N-isopropyl derivative 3a was isolated without column chromatography in more than 70% yield. This KF-alumina catalyzed repeated isopropylation was applicable to N-selective alkylation of other hindered cyclic amides to afford N-alkyl derivatives in high yields.
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Hiroaki TAKAYANAGI, Yumiko OSA, Tomoko SATO, Hiroshi TSUMURAYA, Kazuyo ...
1998 年 46 巻 8 号 p.
1321-1324
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Conformational analysis of methyl 2, 3, 4-tri-O-acetyl-6-deoxy-6-(R)-phenylsulfinyl-α-D-glucopyranoside (1), methyl 2, 3, 4-tri-O-acetyl-6-deoxy-6-(S)-phenylsulfinyl-α-D-glucopyranoside (2) and methyl 2, 3, 4-tri-O-acetyl-6-deoxy-6-phenylsulfonyl-α-D-glucopyranoside (3) in solution (CDCl
3) and the crystalline state was carried out using
1H-NMR spectra and X-ray crystallographic data. The conformational preference of the C6-S bond in the above mentioned compounds was found to be GT (GT is short for gauche-trans), and as a 1 : 1 mixture of rotamers for the (S)-S-oxide (2) and sulfone (3) but not in the (R)-S-oxide (1) in the solid state.
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Akira KAJI, Kengo KIMURA, Masanori TERANISHI, Noriki KIRIYAMA, Masaaki ...
1998 年 46 巻 8 号 p.
1325-1329
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Asterriquinone (ARQ, 1a) is an antitumor metabolite of Aspergillus terreus IFO 6123. To gain insight into the structure-activity relationships of ARQ, a series of chemically modified derivatives (1-6), the ARQ analogues (b-e) and the 2, 5-dihydroxy-p-bezoquinone analogues (f-h), were prepared, and cytotoxic acitivity against mouse leukemia P388 cells investigated. Results indicated that : 1) at least one hydroxy group or acetoxy group in the p-benzoquinone moiety is important to exhibit cytotoxicity; 2) in the p-benzoquinone moiety, a single methoxy group and/or one aceotxy group substitution showed more potent cytotoxicity than when two hydroxy groups are substituted (1); 3) the indole ring is important for the cytotoxicity of ARQ analogues; 4) the 1, 1-dimethly-2-propenyl group in the indole ring is not important for the cytotoxic activity of ARQ.
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Toshihiro ISHII, Kazuhiko TAKATORI, Katsumi IIDA, Teruhiko HIGUCHI, Ak ...
1998 年 46 巻 8 号 p.
1330-1332
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
We have conducted optimizaiton studies to develop a superior
13C-phenylalanine breath test for the diagnosis of liver disease. First, we examined the optimum
13C-labeling position in phenylalanine for use in a breath test based on infrared spectroscopic detection of
13CO
2 in exhaled air. L-[1-
13C]Phenylalanine gave the best result. Next, a suitable dosage to give a short peak time (the time expressed in minutes as which
13CO
2 excretion is maximal) after administration was determined. The
13CO
2/
12CO
2 ratio in exhaled air after administration of 100 mg/body of L-[1-
13C]phenylalanine peaked sharply at 15 min. We also examined the effect of food on the hepatic metabolism of L-[1-
13C]phenylalanine. We found that a fasting period of over 7 h before the test resulted in a higher
13CO
2 peak excretion. The peak appeared sooner than that in the
13C-phenacetin breath test and, therefore, the
13C-phenylalanine breath test appears preferable for the rapid evaluation of hepatic function.
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Sandor KEKI, Tamas SIPOS, Gyorgy DEAK, Geza MEZEY, Miklos ZSUGA
1998 年 46 巻 8 号 p.
1333-1334
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Microprecipitation of folic acid was monitored by the dynamic light scattering (DLS) method. The pH was changed by CO
2 absorption and addition of HCl. The folic acid solutions were examined over the pH range 8.5-4.0. Over the pH range 5.4-6.0, microprecipitation was observed and at pH ≤5.2 crude precipitation of folic acid occurred. The dependence of the effective diameter on the pH over the pH range 5.4-6.0 is also reported.
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Tomohiro MATSUSHIMA, Michiko MORI, Noriyuki NAKAJIMA, Hiroshi MAEDA, J ...
1998 年 46 巻 8 号 p.
1335-1336
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
The C1-C7 fragment (4) of tedanolide (1) was synthesized starting from methyl (R)-3-hydroxy-2-methyl-propionate via a mismatched but highly efficient Sharpless dihydroxylation of the C1-C7 α, β-unsaturated ester (6) with AD-mix-α.
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Kentaro HATANO
1998 年 46 巻 8 号 p.
1337-1338
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Radiofluorination of protected methionine derivatives were examined in the presence of xenon difluoride (XeF
2). The simple reaction procedure with
18F-tetrabutylammonium fluoride and XeF
2 led N-Boc-methionine esters to corresponding
18F-fluoromethyl thioethers. The deprotection of the obtained labeled compounds was unsuccessful. This method expands the range of target molecules that can be labeled by fluorine-18 for noninvasive clinical measurements using positron emission tomography.
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Masayuki YOSHIKAWA, Toshiyuki MURAKAMI, Kenichi YASHIRO, Hisashi MATSU ...
1998 年 46 巻 8 号 p.
1339-1340
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
A potent natural α-glucosidase inhibitor called kotalanol has been isolated from an antidiabetic traditional Ayurvedic medicine, the roots and stems of Salacia reticulata WIGHT, through bioassay-guided separation. The structure of kotalanol was elucidated on the basis of chemical and physicochemical evidence to be the inner salt comprised of 1-deoxyheptosyl-3-sulfate anion and 1-deoxy-4-thio-D-arabinofuranosyl sulfonium cation. Kotalanol was found to show more potent inhibitory activity against sucrase than salacinol and acarbose.
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Hiroshi IMAGAWA, Tokuko SHIGARAKI, Tokiko SUZUKI, Hiroko TAKAO, Hideto ...
1998 年 46 巻 8 号 p.
1341-1342
発行日: 1998/08/15
公開日: 2008/03/31
ジャーナル
フリー
Five- and six-membered ring cyclic ethers are efficiently prepared by exo-mode oxymercuration of the corresponding olefinic alcohols with Hg(OTf)
2. A seven-membered ring ether is prepared using Hg(OTf)
2 along with TMU. However, this procedure is not effective for the preparation of four- and eight-membered ring ethers.
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