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Volume 48, Issue 10
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Koji NAKANISHI2000 Volume 48 Issue 10 Pages 1399-1409
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSRhodopsin, the pigment responsible for vision in animals, insect and fish is a typical G protein (guanyl-nucleotide binding protein) consisting of seven transmembrane alpha helices and their interconnecting extramembrane loops. In the case of bovine rhodopsin, the best studied of the visual pigments, the chromophore is 11-cis-retinal attached to the terminal amino group of Lys296 through a protonated Schiff base linkage. Photoaffinity labeling with a 3-diazo-4-oxo-retinoid shows that C-3 of the ionone ring moiety is close to Trp265 in helix F (VI)in dark inactivated rhodopsin. Irradiation causes a cis to trans isomerization of the 11-cis double bond giving rise to the thghly strained intermediate bathorhodopsin. This undergoes a series of thermal relaxation through lumi-, meta-I and meta-II intermediates after which the retinal chromophore is expelled from the opsin binding poket.Photoaffinity labeling performed with 3-diazo-4-oxoretinal at -196°C for batho-, -80°C for lumi-, -40°C for meta-I, and 0°C for meta-II rhodopsin showed that in bathorhodopsin the ring is still close to Trp265. However, in lumi-, meta-I and meta-II intermediates crosslinking occurs unexpectedly at A169 in helix D (IV).This shows that large movements in the helical arrangements and a flip over of the ring moiety accompanies the transduction (or bleaching) process. These changes in retinal/opsin interactions are necessarily accompanied by movements of the extramembrane loops, which in turn lead to activation of the G protein residing in the cycoplasmic side. Of the numerous G protein coupled receptors, this is the first time that the outline of transduction pathway has been clarified.View full abstractDownload PDF (2266K) -
Mariko KITAJIMA, Ken-ichiro HASHIMOTO, Masashi YOKOYA, Hiromitsu TAKAY ...2000 Volume 48 Issue 10 Pages 1410-1412
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSA new gluco indole alkaloid, 3, 4-dehydro-5-carboxystrictosidine, was obtained from Peruvian Una de Gato(Cat's Claw, original plant : Uncaria tomentosa) together with two known gluco indole alkaloids. This compound was the first example of isolation of a gluco monoterpenoid indole alkaloid having a 3, 4-dihydro-β-carboline ring system from nature. A characteristc feature of the compound was the quick replacement of the methylene hydrogens on C-14 with deuterium that was observed when it was dissolved in CD3OD. We demonstrated a similar proton-deuterium exchange on a model compound, 1-methyl-3, 4-dihydro-β-carboline, in CD3OD solution.View full abstractDownload PDF (483K) -
Jing HUANG, Yukio OGIHARA, Hao ZHANG, Noriko SHIMIZU, Tadahiro TAKEDA2000 Volume 48 Issue 10 Pages 1413-1417
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSFour new triterpenoid saponins, ardisimamilloside C (1), 3-O-{α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl-(1→4)-[β-D-glucopyranosyl-(1→2)]-α-L-arabinopyranosyl}-3β, 16α, 28, 30-tetrahydroxy-olean 12-en, ardisimamilloside D (2), 3-Or-{α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl-(1→4)-[β-D-glucopyranosyl-(1→2)]-α-L-arabinopyranosyl}-3β, 15α, 28, 30-tetrahydroxy-olean-12-en, ardisimamilloside E (3), 3-O-{α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl-(1→4)-[β-D-glucopyranosyl-(1→2)]-α-L-arabinopyranosyl}-13β, 28-epoxy-3β, 16α, 29-oleananetriol, and ardisimamilloside F (4), 3-O-{α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl-(1→4)-[β-D-glucopyranosyl-(1→2)]-α-L-arabinopyranosyl}-3β, 16α-dihydroxy-13β, 28-epoxy-oleanan-30-oic acid were isolated from the roots of Ardisia mamillata HANCE. Structure assignments were established on the basis of highresolution (HR)-FAB-MS, 1H-, 13C-, and two-dimensional (2D)-NMR spectra, and on hte chemical evidence.View full abstractDownload PDF (842K) -
Kazuko YOSHIKAWA, Kenji MATSUMOTO, Chie MINE, Shinya BANDO, Shigenobu ...2000 Volume 48 Issue 10 Pages 1418-1421
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSFive lanostane triterpenes, named versisponic acids A-E and three lanostanoid glycosides, laetiposides E-G, were isolated from the fruit bodies of Laetiporus versisporus. Their stuctures were established by extensive NMR experiments and chemical methods.View full abstractDownload PDF (607K) -
Tomoo HOSOE, Hideaki OKADA, Takeshi ITABASHI, Koohei NOZAWA, Kaoru OKA ...2000 Volume 48 Issue 10 Pages 1422-1426
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSIn the course of searching for new antifungal agents, a new pentanorlanostane derivative, cladosporide A(1), was isolated along with ergosterol, ergosterol peroxide and 23, 24, 25, 26, 27-pentanorlanost-8-ene-3β, 22-diol(2) form Cladosporium sp. as a characteristic antifungal agent against the human pathogenic filamentous fungus Aspergillus fumigatus. The structure of 1 was established as 3β, 22-dihydroxy-23, 24, 25, 26, 27-pentanorlanostane-29-al by spectroscopic and chemical investigation and X-ray crystallographic analysis. Inhibitory activity against A. fumigatus (IC800.5-4.0 μg/ml) was observed for cladosporide A (1), but bo activity was observed against pathogenic yeasts, Candida albicans and Cryptococcus neoformans, and other parhogenic filamentous fungi, Aspergillus niger and A. flavus. The 4β-aldehyde residue in 1 might be essential for the antifungal activity, since 23, 24, 25, 26, 27-pentanorlanost-8-ene-3β, 22-diol (2) showed no inhibition against the above four fungi.View full abstractDownload PDF (793K) -
Masahiro NAGAI, Nobuko SAKURAI, Nobuyuki YUMOTO, Seiji NAGUMO, Shujiro ...2000 Volume 48 Issue 10 Pages 1427-1428
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSFrom the twigs of Myrica cerifera L. (Myricaceae), a new oleanane triterpenic acid named myrica acid was isolated along with myricalactone and several other known constituents. The structure of the acid was determined as 3β-hydroxy-1-oxoolean-11, 13(18)-dien-28-oic acid on the basis of chemical and spectral evidence.View full abstractDownload PDF (478K) -
Hisashi MATSUDA, Toshiyuki MURAKAMI, Norihisa NISHIDA, Tadashi KAGEURA ...2000 Volume 48 Issue 10 Pages 1429-1435
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSFrom the methanolic extract with vasorelaxant activity obtained from Angelica furcijuga KITAGAWA, four new khellactone-type coumarins, hyuganins A, B, C, and D, were isolated together with twelve known coumarins, two known acetylenic compounds, and a known lignan. The structures of hyuganins A, B, C, and D were determined on the basis of chemical and physicochemical evidence. Nine principal coumarins (hyuganin A, anomalin, pteryxin, isopteryxin, isoepoxypteryxin, praerosides II and IV, apiosylskimmin, (R)-peucedanol 7-O-β-D-glucopyranoside), two acetylenic compounds [(-)-falcarnol and falcarindiol], and related compounds were examined for inhibitory activities on high concentration of K+ (High K+)- and dl-norepinephrine (NE)-induced contractions. The results indicate that the 3'-and 4'-acyl groups of khellactone-type coumarins are essential for the inhibitory activity on the contractions by High K+. Hyuganin A and anomalin showed inhibitory effects on High K+-induced contraction, but not on NE-induced contraction. Other active coumarins (pteryxin, isopteryxin, isoepoxypteryxin) and an acetylenic compound (falcarindiol) non-selectively inhibited both contractions by High K+ and NE.View full abstractDownload PDF (983K) -
Haruhiro FUJIMOTO, Etsuko NAKAMURA, Emi OKUYAMA, Masami ISHIBASHI2000 Volume 48 Issue 10 Pages 1436-1441
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSFractionation monitored by the immunomodulatory activity of the AcOEt extract of an Ascomycete, Emericella aurantio-brunnea, afforded two known fungal sesterterpenes, variecolin (1) and variecolactone (2), two new variecolin congeners named variecoacetals A (3) and B (4), and a new sesquiterpenetriol diester named emeremophiline (5), as the immunosuppressive constituests of this fungus. The absolute configuration of 1, which was previously not determined, was determined to be (2S, 3S, 6R, 10S, 11R, 14S, 15R, 16S) from the NMR spectral data of the (6R, 7R)-dimethyl-1, 3, 5-trioxacycloheptyl derivative of 1 (7). The absolute configurations of the other variecolin congeners, 2-4, and variecolol (6) are also proposed form biosynthetic considerations.View full abstractDownload PDF (859K) -
Noriko ARAI, Kazuro SHIOMI, Yuuici YAMAGUCHI, Rokuro MASUMA, Yuzuru IW ...2000 Volume 48 Issue 10 Pages 1442-1446
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSA new chitinase inhibitor, designated as argadin (1), was isolated form the cultured broth of a fungal strain FO-7314. The strain was identified as Clonostachys sp. from the morphological characteristics. Argadin was purified from the cultured mycelium by a combination of cation exchange, adsorption and gel filtration chromatographic methods. The structure of argadin was elucidated as cyclo(Nω-acetyl-L-arginyl-D-prolyl-homoseryl-histidyl-L-2-aminoadipyl) in which homoseryl γ-methylene bonded to histidyl α-amino residue. The IC50 value of argadin against Lucilia cuprina (blowfly) chitinase was 150 nM at 37°C and 3.4 nM at 20°C. Argadin arrested the moult of cockroach larvae upon injection into the ventral abdominal part.View full abstractDownload PDF (904K) -
Takaaki KUBOTA, Masashi TSUDA, Miho TAKAHASHI, Masami ISHIBASHI, Seiko ...2000 Volume 48 Issue 10 Pages 1447-1451
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSColopsinols D (1) and E (2), two new polyhydroxyl linear carbon chain compounds, have been isolated form the cultured marine dinoflagellate Amphidinium sp. The structures of 1 and 2 were elucidated on the basis of two-dimensional NMR and FAB-MS/MS data.View full abstractDownload PDF (648K) -
Michio NAMIKOSHI, Hisayoshi KOBAYASHI, Takeshi YOSHIMOTO, Shiori MEGUR ...2000 Volume 48 Issue 10 Pages 1452-1457
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSTwo new compounds, paecilospirone (1) and phomopsidin (2), and seven known compounds, chaetoglobosin A (3), griseofulvin (4), fusarielin A (5), fusapyrone (6), deoxyfusapyrone (7), and verrucarins J (8) and L acetate(9), have been isolated and characterized from marine-derived fungi collected in tropical and sub-tropical coral reef environments. The utility of marine-derived fungi as a source of bioactive secondary metabolites is discussed.View full abstractDownload PDF (917K) -
Masami Yokota HIRAI, Hedeyuki SUZUKI, Mami YAMAZAKI, Kazuki SAITO2000 Volume 48 Issue 10 Pages 1458-1461
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSThe bitter and sweet forms of a plant species differing with alkaloid contents may provide a model system for investigation of alkaloid biosynthesis at a molecular level. The pattern and concentration of quinolizidine alkaloids were determined by capillary GC-MS in bitter and sweet plants of Lupinus angustifolius. Bitter plant contained lupanine, 13α-hydroxylupanine, angustifoline, α-isolupanine, tetrahydrorhombifoline, and ester-derivatives of 13α-hydroxylupanine. In contrast, no alkaloid was detected in sweet plant. The enzymatic activity of acyltransferase fo formation of 13α-tigloyloxylupanine was similar or even higher in the cell-free extracts of sweet plant than that in bitter plant. These results suggest that the biosynthetic step(s) of ring closure forming the initial cyclic alkaloid, lupanine, from cadaverine is presumably blocked in sweet plant, and that the later steps for modification of the cyclized alkaloids are not altered. We hypothesized that the gene(s) encoding enzyme(s) for ring-closure step might be repressed in sweet plant, and that the expresion might take place only in bitter plant. To isolate the genes specifically expressed in bitter plant, cDNA-amplified fragment length polymorphism (cDNA-AFLP) analysis was carried out. However, no bitter-specific gene was isolated, suggesting that alkaloid biosynthesis in sweet plant may be down-regulated at a post-transcriptional level.View full abstractDownload PDF (690K) -
Hideko KANAZAWA, Chizuko MIYATA, Yoshiko NAGATA, Shiro URANO, Yoshikaz ...2000 Volume 48 Issue 10 Pages 1462-1466
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSα-Tocopherol and α-tocopherylquinone in rat tissues and plasma were determined simulaneously by using high-performance liquid chromatography-electrochemical detection (HPLC-ED) with dual electrodes in the series mode. Biological samples were saponified in the presence of a mixture of butylated hydroxytoluene, ascorbic acid, and pyrogallol and then extracted with hexane. The compounds were separated on a C18 column using a mobile phase containing 95% methanol and 0.05 M sodium perchlorate as the supporting electrolyte. After HPLC separation, α-tocopherylquinone was first reduced at an upstream electrode at -500mV. Both α-tocopherol and the reduction product of α-tocopherylquinone were then oxidized downstream at +600 mV. Only the downstream electrode current was monitored for the determination. Linearity of the standard curves was obtained over the range 5-30 pmol for α-tocopherol and α-tocopherylquinone. Minimum detectable quantities(S/N of 3) were 0.25 pmol for α-tocopherol and 0.31 pmol for α-tocopherylquinone. The method was applied to analysis of the contents of α-tocopherol and α-tocopherylquinone in rat tissues and plasma. By hyperoxia, the content of α-tocopherol was decreased remarkably in lung, and in contrast, the contents of α-tocopherylquinone were increased in all tissues studies with the exception of plasma, though the content of α-tocopherylquinone in normal rats is quite small. The technique is particularly useful in the quantitation of the oxidation of α-tocopherol in biological samples.View full abstractDownload PDF (701K) -
Masahiro OGATA, Midori HOSHI, Shiro URANO, Toyoshige ENDO2000 Volume 48 Issue 10 Pages 1467-1469
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSSince the inhibitory effect of eugenol (a), which was isolated as an antioxidative component form plant, Caryopylli flos, on lipid peroxidation was less than that of α-tocopherol, we synthesized the eugenol-related compounds dieugenol(b), tetrahydrodieugenol(c), and dihydroeugenol(d), to find new strong antioxidants and assessed them for their inhibitory effect on lipid peroxidation and scavenging ability for superoxide and hydroxyl radicals. The antioxidative activities were in the order : (b)>(c)>(d)>(a) for the thiobarbituric acid reactive substance (TBARS) formation. These results suggest that the dimerized compounds have higher antioxidant activities than that of the monomers. Electron spin resonance (ESR) spin trapping experiments revealed that eugenol and its dimer, having allyl groups in the structure, scavenged superoxide, and that only eugenol trapped hydroxyl radicals under the conditions used. These finding suggest that eugenol and dieugenol have a different mechanism of antioxidation, i.e. eugenol may inhibit lipid peroxidation at the level of initiation, however, the related dimeric compounds may inhibit lipid peroxidation at the level of propagation of free radical chain reaction like α-tocopherol.View full abstractDownload PDF (579K) -
Tadashi EGUCHI, Shinobu KANAI, Katsumi KAKINUMA, Tadayasu OKAZAKI, Kaz ...2000 Volume 48 Issue 10 Pages 1470-1473
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSA novel potentiator of nerve growth factor (NGF), NG-061, which had been isolated from the fermentation broth of Penicillium minioluteum F-4627, was synthesized from methoxybenzoquinone and phenylacetylhydrazine in a single step. Aseries of acyl hydrazone derivatives were also synthesized and their potentiator activity of neurotrophic effect of NGF on neurite outgrowth was evaluated by assay with a rat pheochromocytoma cell line PC12.View full abstractDownload PDF (789K) -
Masuo MORISAK, Tomoko IGATA, Satomi YAMAMOTO2000 Volume 48 Issue 10 Pages 1474-1479
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSAs a potential inhibitor and/or mechanistic probe for lanosterol 14α-demethylase, 15α-fluoro-24, 25-dihydrolanosterol was prepared by fluorination of 15α-hydroxy-24, 25-dihydrolanost-7-en-3β-yl benzoate with diethyl-aminosulfur trifluoride, followed by hydrogen chloride-catalyzed isomerization of the Δ7 to Δ8 and reductive cleavage of the benzoate.View full abstractDownload PDF (848K) -
Yuko KAJI, Takeshi KOAMI, Atsuko NAKAMURA, Yoshinori FUJIMOTO2000 Volume 48 Issue 10 Pages 1480-1483
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESS3-Epi-6, 7-dideoxyxestobergsterol A (2), an analogue of xestobergsterol A, has been synthesized from dehydroepiandrosterone (3) in 15 steps. The key synthetic intermediate, 15β, 16α-dioxypregn-17(20)E-ene derivative 8, was prepared from the corresponding 15β, 16β-epoxide 6 by reating with acetic acid and titanium tetraisopropoxide. The 23-oxo side chain was constructed stereoselectively by orthoester Claisen rearrangement of 8 followed by introduction of an isobutyl group. Basic treatment of the 15, 23-diketone 12 followed by deprotection gave the title compound 2.View full abstractDownload PDF (781K) -
Masato SHIMIZU, Yukiko IWASAKI, Akiko OHNO, Sachiko YAMADA2000 Volume 48 Issue 10 Pages 1484-1493
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSTo study the interaction of vitamin D with its receptor by 19F-NMR, (5Z, 10Z)-and (5Z, 10E)-19-fluoro-1α, 25-dihydroxyvitamin D3 were synthesized starting from vitamin D2 via electrophilic fluorination of vitamin D-SO2 adducts as the key step. Regio- and stereoselective electrophilic fluorination at C(19) of vitamin D-SO2 adducts was achieved under the conditions using (PhSO2)2NF and bulky bases. The stereochemistry of the addition and elimination of SO2 of various vitamin D derivatives was studied in detail. SO2 causes Z-E isomerization of the 5, 6-double bond of vitamin D and adds to the resulting (5E)-isomer form the sterically less hindered side opposite to the substituent at C(1). Elimination of SO2 from 19-substituted vitamin D-SO2 adducts proceeded exclusively in a suprafacial manner with respect to the diene part under either thermal or reductive conditions. Dyesensitized photochemical isomerization of 19-fluorovitamin D derivatives was studied in detail. The rapid isomer ization at the 5, 6-double bond was followed by the slow isomerization at the 10, 19-double bond to yield the(5E, 10Z)-isomer (by nomenclature of the 1-OH derivatives) as the major product. (10Z)- and (10E)-19-Flurovitamin Ds were also interconverted thermally probably via the corresponding previtamin D by 1, 7-sigmatropic isomerization.View full abstractDownload PDF (1581K) -
Hiroyasu TAKAHASHI, Sonei SOU, Ryu YAMASAKI, Mikiko SODEOKA, Yuichi HA ...2000 Volume 48 Issue 10 Pages 1494-1499
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSα-Glucosidase inhibitors with a phthalimide skeleton were prepared. Structure-activity relationship studies indicated a critical role for the hydrophobicity of the substituent at the nitrogen atom of the phthalimide skeleton. Introduction of electron-withdrawing groups, including a nitro group and chlorine, influenced the activity.Optimization studies led us to design 4, 5, 6, 7-tetrachloro-N-phenylphthalimide (CP0P) and its N-phenylalkyl derivatives. CP0P and 4, 5, 6, 7-tetrachloro-N-(4-phenylbutyl)phthalimide (CP4P) proved to be more potent α-glucosidase inhibitors than the known inhibitor 1-deoxynojirimycin.View full abstractDownload PDF (904K) -
Satoko ISHIKAWA, Noriko SAITOH, Masataka MOCHIZUKI2000 Volume 48 Issue 10 Pages 1500-1503
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSNovel N-nitroso-N-(acetoxymethyl)-ω-chloroalkylamines were synthesized and their chemical and biological properties were evaluated. The nitrosamines were expected to decompose through ω-chloroalkyldiazohydroxides in aqueous solution, and then to alkylate various cellular macromolecules. N-Nitroso-N-(acetoxymethyl)-2-chloroethylamine rapidly decomposed in aqueous solution, and the reaction rate was apparently independent of the pH of the solution. On the other hand, the rate of decomposition of chloropropyl and chlorobutyl homologs was pH-dependent, and increased in alkaline solution. When mutagenicity was assayed in Salmonella typhimurium TA1535 and TA92 for preliminary evaluation, all three compounds were directly mutagenic. The mutagenicity in Salmonella typhimurium TA1535, which can detect base-pair change mutation, clearly showed that these compounds induced DNA alkylation in vivo. The increase of alkyl chain lenght in chloroalkyl compounds increased the mutagenic activity, and the activities were stronger than those of the corresponding simple α-acetoxy nitrosamines lacking a chloro group, N-nitroso-N-(acetoxymethyl)alkylamines. Furthermore, the positive result in TA92 suggested that chlorinated nitrosamines cross-linked DNA like antitumor chloroethylnitrosoureas and that they are expected to be new lead compounds for antitumor agents.View full abstractDownload PDF (699K) -
Kiminori OHTA, Emiko KAWACHI, Noriko INOUE, Hiroshi FUKASAWA, Yuichi H ...2000 Volume 48 Issue 10 Pages 1504-1513
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSSeveral pyridine-and pyrimidine-carboxylic acids were synthesized as ligand candidates for retinoid nuclear receptors, retinoic acid receptors (RARs) and retinoic X receptors (RXRs). Although the pyridine derivatives, 6-[(5, 6, 7, 8-tetrahydro-5, 5, 8, 8-tetramethyl-2-naphthalenyl)carbamoyl]pyridine-3-carboxylic acid (2b) and 6-[(5, 6, 7, 8-tetrahydro-5, 5, 8, 8-tetramethyl-2-naphthalenyl)carboxamido]pyridine-3-carboxylic acid (5b) are more potent than the corresponding benzoic acid-type retinoids, Am80 (2a) and Am580 (5a), the replacement of the benzene ring of Am580 (5a), Am555 (6a), or Am55 (7a) with a pyrimidine ring caused loss of the retinoidal activity both in HL-60 cell differentiation assay and in RAR transactivation assay using COS-1 cells. On the other hand, pyrimidine analogs (PA series, 10 and 11) of potent RXR agonists (retinoid synergists) with a diphenylamine skeleton (DA series, 8 and 9) exhibited potent retinoid synergistic activity in HL-60 cell differentiation assay and activated RXRs. Among the synthesized compounds, 2-[N-n-propyl-N-(5, 6, 7, 8-tetrahydro-5, 5, 8, 8-tetramethyl-2-naphthalenyl)amino]pyrimidene-5-carboxylic acid (PA013, 10e) is most active retinoid synergist in HL-60 assay.View full abstractDownload PDF (1533K) -
Masakazu TAMURA, Yasuteru URANO, Kazuya KIKUCHI, Tsunehiko HIGUCHI, Ma ...2000 Volume 48 Issue 10 Pages 1514-1518
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSSuperoxide is involved in the pathogenesis of various diseases, such as inflammation, ischemia-reperfusion injury and carcinogenesis. Superoxide dismutases (SODs) catalyze the disproportionation reaction of superoxide to produce oxygen and hydrogen peroxide, and can protect living cells against the toxicity of free radicals derived from oxygen. Thus, SODs and their functional mimics have potential value as pharmaceuticals. We have previously reorted that Fe(II)tetrakis-N, N, N', N'-(2-pyridylmethyl)ethylenediamine (Fe(II)TPEN) has an excellent SOD activity (IC50=0.5μM) among many iron complexes examined (J. Biol. Chem., 264, 9243-9249(1989)).Fe(II)TPEN can act like native SOD in living cells, and protect Escherichia coli cells from free radical toxicity caused by paraquat.In order to develop more effective SOD functional mimics, we synthesized Fe(II)TPEN derivatives with electron-donating or electron-withdrawing groups at the 4-position of all pyridines of TPEN, and measured the SOD activities and the redox potentials of these complexes. Fe(II) tetrakis-N, N, N', N'-(4-methoxy-2-pyridylmethyl)ethylenediamine (Fe(II)(4MeO)4TPEN) had the highest SOD activity (IC50=0.1 μM) among these iron-based SOD mimics. In addition, a good correlation was found between the redox potential and the SOD activity of 15 Fe(II)complexes, including iron-based SOD mimics reported in the previous paper (J. Organometal. Chem., in press).Iron-based SOD mimics may be clinically applicable, because these complexes are generally tissue-permeable and show low toxicity. Therefor our findings should be significant for the development of clinically useful SOD mimics.View full abstractDownload PDF (738K) -
Shuji AKAI, Tadaatsu NAKA, Yasushi TAKEBE, Yasuyuki KITA2000 Volume 48 Issue 10 Pages 1519-1523
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSThe lipase-catalyzed asymmetric desymmetrization of the prochiral 2, 2-disubstituted 1, 3-propanediols was studied using various types of 1-ethoxyvinyl esters (1a-i). Although 1a-e with aliphatic acyl groups were not sufficient, use of the benzoate (1f) in combination with Candida rugosa lipases converted acyclic diols (2, 6) and cyclic diols (11-14) to the optically active compounds (3f, 7f, 15f-18f), bearing a quaternary carbon center, with moderate-to-high optical yields. These products were fairly stable against racemization under acidic conditions.View full abstractDownload PDF (825K) -
Nozomi TSUTSUMI, Takashi ITOH, Akio OHSAWA2000 Volume 48 Issue 10 Pages 1524-1528
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSDisulfide bond was cleaved by a catalytic amount of nitric oxide in the presence of oxyge, which was confirmed by experiments employing two symmetrical disulfides. The reaction resulted in the formation of unsym-metrical disulfides in nearly 50% yields. The steric hindrance of alkyl disulfide slowed the reaction rate, and an electron-donating group on the aryl disulfide promoted the reaction. The substituent and S-nitrosothiol effects suggested that the reaction was initialized with an oxidative process by NO+.View full abstractDownload PDF (773K) -
Mariko GOTO, Koh-ichi AKIMOTO, Kazumasa AOKI, Mitsuru SHINDO, Kenji KO ...2000 Volume 48 Issue 10 Pages 1529-1531
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSThe reactions of the lithium enolate of 1-tetralone with reactive alkyl halides were examined in the absence and in the presence of 3 eq of various ligands for the lithium. It is shown that the rates of the reactions are enhanced greatly in the presence a tetradentate amine (1, 1, 4, 7, 10, 10-hexamethyltriethylenetetramine), and the ratio of the monoalkylated product to the dialkylated product is increased under shorter reaction times.View full abstractDownload PDF (552K) -
Kiyoshi FUKUHARA, Yukie HARA, Ikuo NAKANISHI, Naoki MIYATA2000 Volume 48 Issue 10 Pages 1532-1535
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSSuperoxide radical anion (O·-2), generated by KO2/crown ether, is effective for hydroxylation of nitronaphthalenes. When mono- and di-nitronaphthalenes are treated with KO2/crown ehter, hydroxylation results at the electron-deficient site caused by the electron withdrawing effect of the substituted nitro group. Kinetic experiments suggest that the hydroxylation proceeds by two different mechanisms dependent on the first one-electron reduction potential of nitronaphthalenes.View full abstractDownload PDF (631K) -
Toshihiro KIGUCHI, Yuko TSURUSAKI, Satoshi YAMADA, Mariko ASO, Masakaz ...2000 Volume 48 Issue 10 Pages 1536-1540
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSAsymmetric spirocyclization based on intramolecular conjugate addition using a combination of a Lewis acid and an optically active cyclohexane-1, 2-diol has been studied in connection with 1) the effect of substituents on the cyclohexane-1, 2-diol and 2) the effect of substituents on the substrate. This reaction was found to be both thermodynamically and kinetically controlled under restricted conditions.View full abstractDownload PDF (780K) -
Shigeki HOSHIMOTO, Hirofumi MATSUNAGA, Takehisa KUNIEDA2000 Volume 48 Issue 10 Pages 1541-1544
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSThe "roofed" chiral 2-thiazolidinones, which are sterically congested and conformational rigid, and which are perpared by the [4+2] cycloaddition of 2-thiazolone to the cyclic dienes, dimethylanthracene and hexamethylcyclopentadiene, followed by optical resolution with (1S, 2R)-2-methyoxy-1-apocamphanecarbonic acid (MAC acid) are of considerable promise for use as chiral auxiliaries for the alkylation of enolates.View full abstractDownload PDF (683K) -
Toshio HONDA, Katsunori ENDO, Satoko ONO2000 Volume 48 Issue 10 Pages 1545-1548
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSPreparation of 6-substituted 4-hydroxytetrahydro-2H-pyran-2-one (12), a key intermediate for the synthesis of (-)-tetrahydrolipstatin, was achieved in an optically pure form by employing an enantioselective deprotonation reaction of the prochiral bicyclic derivative (5) as a key step.View full abstractDownload PDF (703K) -
Naoki SAITO, Masashi TACHI, Ryu-ichi SEKI, Hiroshi KAMAYACHI, Akinori ...2000 Volume 48 Issue 10 Pages 1549-1557
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSA practical synthesis of 1, 2, 3, 4, 5, 6-hexahydro-1, 5-imino-10-hydroxy-9-methoxy-3, 8, 11-trimethyl-3-benzazocin-4-one (3) as an ABC ring model compound of ecteinascidin 743 and safracins from 3-hydroxy-4-methoxy-5-methylbenzaldehyde (7) is described. The overall yield in 15 steps is 27%.View full abstractDownload PDF (1402K) -
Hideaki MURATAKE, Aki HAYAKAWA, Mitsutaka NATSUME2000 Volume 48 Issue 10 Pages 1558-1566
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSFive A-ring analogs of duocarmycin SA 9a-e were synthesized in racemic form modifying our second synthetic route toward duocarmycin SA. The problem encountered at the crucial phenol forming step to secure 17a, b from 16a, b under the conventionally used Kuwajima conditions was overcome by division a more convenient method : simple heating of 16a-c in benzene in the presence of bis(triphenylphosphine)palladium(II) chloride(10 mol%), cesium carbonate (3 eq), and triphenylphosphine (0.3 eq) gave 17a-c in high yields of 86-91%. The intermediates 17a-e were readily led to the A-ring analogs (±)-9a-e almost according to the reported route.View full abstractDownload PDF (1624K) -
Masayuki MURAKAMI, Keijiro KOBAYASHI, Koichi HIRAI2000 Volume 48 Issue 10 Pages 1567-1569
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSAcidic segment of an acyl-CoA : cholesterol acyltransferase (ACAT) inhibitor, R-106578 was synthesized by enantioselective hydrogenation of the Z-olefine (9-(Z)) using (R)-2, 2'-bis(diphenylphosphino)-1, 1'-binaphthyl(BINAP)-Ru(OAc)2 as a catalyst in methanol at 100°C, 5kgf/cm2 of H2 pressure. The requisite Z-olefine was prepared regioselectively via coumarin derivative (5).View full abstractDownload PDF (575K) -
Yuko HIDAI, Toshiyuki KAN, Tohru FUKUYAMA2000 Volume 48 Issue 10 Pages 1570-1576
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSTotal synthesis of spider toxins HO-416b (1) and Agel-489 (2) was accomplished using the 2-nitrobenzenesulfonamide (Ns) group as both a protecting and activating group. In this strategy, the C-N bonds were constructed by alkylation of sulfonamides with alkyl halides or Mitsunobu reaction with the corresponding alcohol.Beginning with monoprotection of the symmetrical diamine, the construction of the backbone from diamine 3 was efficiently accomplished in 7 steps for 14 and 9 steps for 29. Removal of the Ns group while the substrate was attached to a novel solid support enabled the efficient isolation of this highly polar compound.View full abstractDownload PDF (1241K) -
Takeshi KAMBARA, Kiyoshi TOMIOKA2000 Volume 48 Issue 10 Pages 1577-1580
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSA catalytic amount of external chiral bisoxazoline ligand 3a bearing an isopropyl group as a stereocontrolling group catalyzed a reaction of a lithium ester enolate 4b, generated from 3-pentyl 2-methylpropionate, with benzaldehyde anisidine-imine 5 to afford corresponding β-lactam 6 in higher 70% ee than that obtained by the reaction using a stoichiometric amount of the ligand. A bulkier ligand 3d bearing a phenyl group gave 81% and 6% ees in stoichiometric and catalytic reactions, respectively. Examination of the varying factors suggested the involvement of mixed aggregates as a reactive species. A working model is presented for prediction of the sense of asymmetric induction.View full abstractDownload PDF (626K) -
Masahisa NAKADA, Masashi TAKANO, Yukitaka IWATA2000 Volume 48 Issue 10 Pages 1581-1585
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSThe dianion of the acetoacetic ester reacts with epibromohydrin derivatives to affored a mixture of (Z)-2-alkoxycarbonylmethylidenetetrahydrofuran derivative and (E)-2-alkoxycarbonylmethylidenetetrahydropyran derivative. The selective formation of the tetrahydrofuran derivative is achieved by the use of LiClO4 as the additive. The preparation of the optically active tetrahydrofuran derivatives and tetrahydropyran derivatives is also examined, and the optical purity and absolute configuration of the products is elucidated.View full abstractDownload PDF (785K) -
Masahiro TAKAMURA, Yoshitaka HAMASHIMA, Hiroyuki USUDA, Motomu KANAI, ...2000 Volume 48 Issue 10 Pages 1586-1592
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSA general asymmetric Strecker-type reaction is reported, catalyzed by the Lewis acid-Lewis base bifunctional catalyst 1. The reaction of trimetylsilyl cyanide (TMSCN) with various fluorenyl imines, including n-aldimines and α, β-unsaturated imines, proceeds with good to excellent enantioselectivities in the presence of a catalytic amount of phenol as additive (20 mol%)(catalytic system 1). The products were successfully converted to the corresponding amino acid derivatives in high yields without loss of enantiomeric purity. Furthermore, hydrogenation or dihydroxylation of the products from α, β-unsaturated imines afforded saturated or functionalized aminonitriles also without loss of enantiomeric putiry. The absolute configuration of the products and a control experiment using catalyst 2 supported the proposed dual activation of the imine and TMSCN by the Lewis acid (Al) and the Lewis base moiety (phosphine oxide) of 1. From the mechanistic studies including kinetic and NMR experiments of the catalytic species, the role of PhOH seems to be a proton source to protonate the anionic nitrogen of the intermediate. Specifically, we have found that TMSCN is more reactive than HCN in this catalytic system, probably due to the activation ability of the phosphine oxide moiety of 1 toward TMSCN. This fact prompted us to develop the novel catalytic system 2, consisting of 1 (9 mol%), TMSCN (20 mol%) and HCN(1.2 mol eq). This new system afforded comparable results with obtained by system 1 (1 (9 mol%)-TMSCN(2 mol eq)-PhOH (20 mol%)).View full abstractDownload PDF (1193K) -
Mitsuhiro ARISAWA, Maki TAKAHASHI, Emiko TAKEZAWA, Takenobu YAMAGUCHI, ...2000 Volume 48 Issue 10 Pages 1593-1596
Published: October 01, 2000
Released on J-STAGE: March 31, 2008
JOURNAL FREE ACCESSAn efficient synthetic method for the preparation of optically active pyrroloazocine, pyrroloazepine, quinolizidene, indolizidine using ring closing olefin metahesis (RCM) is described.View full abstractDownload PDF (655K)
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