Noboru Murofushi

Publications (43)66.7 Total impact

• Article: Asymmetric synthesis and stereochemical structure-activity relationship of (R)- and (S)-8-[1-(2,4-dichlorophenyl)-2-imidazol-1-yl-ethoxy] octanoic acid heptyl ester, a potent inhibitor of allene oxide synthase.

  Keimei Oh, Yoichiro Shimura, Kyoko Ishikawa, Yudai Ito, Tadao Asami, Noboru Murofushi, Yuko Yoshizawa
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  ABSTRACT: The preparation of both enantiomers of 8-[1-(2,4-dichlorophenyl)-2-imidazol-1-yl-ethoxy] octanoic acid heptyl ester (JM-8686), a potent inhibitor of allene oxide synthase, has been achieved using 2,4-dichlorophenacyl bromide as a starting material. The key step was the asymmetric reduction of 1-(2,4-dichlorophenyl)-2-imidazol-1-yl-ethanone with chiral BINAL-H. The products were purified by chiral high-performance liquid chromatography (HPLC) to afford pure (R)-JM-8686 and (S)-JM-8686. The inhibitory activities and binding affinities of these enantiomers toward allene oxide synthase were determined. We found that the inhibition potency of (R)-JM-8686 is approximately 200 times greater than that of (S)-JM-8686, with IC(50) values of approximately 5+/-0.2 nM and 950+/-18 nM, respectively. The dissociation constants of (R)-JM-8686 and (S)-JM-8686 with respect to the recombinant allene oxide synthase were approximately 1.4+/-0.3 microM and 4.8+/-0.6 microM, respectively.
  Bioorganic & medicinal chemistry 03/2008; 16(3):1090-5. · 2.82 Impact Factor
• Article: Characterization of novel imidazole derivative, JM-8686, a potent inhibitor of allene oxide synthase.

  Keimei Oh, Tadao Asami, Kenji Matsui, Gregg A Howe, Noboru Murofushi
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  ABSTRACT: The inhibitory properties of a first synthetic jasmonic acid biosynthesis inhibitor, JM-8686, were investigated. Steady-state kinetic analysis indicates that the compound is a competitive inhibitor of allene oxide synthase (AOS) with a K(i) value of approximate 0.62+/-0.15 microM. Dialysis experiment indicates that AOS inactivation by JM-8686 is reversible. The optical difference spectroscopy analysis of JM-8686 and AOS interaction indicates that JM-8686 induced type II binding spectra with a K(d) value of approximate 1.6+/-0.2 microM, suggesting that JM-8686 binds to the prosthetic heme iron of AOS. Comparison of the inhibitory potency of the compound against HPL (CYP74B) from tomato revealed that JM-8686 was a highly selective inhibitor for AOS.
  FEBS Letters 11/2006; 580(24):5791-6. · 3.54 Impact Factor
• Article: Design and synthesis of novel imidazole derivatives as potent inhibitors of allene oxide synthase(CYP74).

  Keimei Oh, Noboru Murofushi
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  ABSTRACT: Allene oxide synthase (AOS) is a key enzyme in the oxylipin pathway in plants leading to jasmonic acid and other jasmonates (JAs), important signal mediators of defense signal networks in plants. AOS uses hydroperoxylinolenic acid as an oxygen donor as well as the substrate, thus the biochemical conversion of 13(S)-hydroperoxylinolenic acid to allene oxide can proceed in the absence of oxygen and NADPH. We have designed the synthesized of a series of novel imidazole derivatives and tested them in a bioassay as AOS inhibitors using a purified recombinant AOS enzyme isolated from Arabidopsis and expressed in E. coli. Among the derivatives prepared, heptyl 8-[1-(2,4-dichlorophenyl)-2-imidazolylethoxy]octanoate (k) was found to be the most potent inhibitor, with an IC(50) of 10+/-5 nM, which is 250,000-fold and 1,000,000-fold more potent than the known AOS inhibitors, acetylsalicyclic acid (2.5 mM) and ketoconazole (10 mM), respectively.
  Bioorganic & Medicinal Chemistry 01/2003; 10(12):3707-11. · 2.92 Impact Factor
• Article: 4′-Alkoxy derivatives of abscisic acid: a promising new probe for mechanisms of abscisic acid perceptions

  Tadao Asami, Yong Ki Min, Sun Young Han, Nobutaka Kitahata, Keimei Oh, Noboru Murofushi, Shigeo Yoshida
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  ABSTRACT: The preparation of new compounds for exploring the molecular andbiochemical mechanisms of abscisic acid signal perception is described. The4-carbonyl group of abscisic acid was replaced with either benzyloxy orn-octyloxy groups. Both modified products possessedABA-like activity in bioassays using barley aleurone protoplasts. The benzyloxyderivative was active in dehydrin induction tests, but not in inhibition of-amylase induction tests. The difference in the activity of this chemical inthe two assay systems suggests that the perception system for the inhibition ofamylase induction systems differs from that of dehydrin induction.
  Plant Growth Regulation 10/2002; 38(3):237-241. · 1.60 Impact Factor
• Article: A novel transposon tagging element for obtaining gain-of-function mutants based on a self-stabilizing Ac derivative

  Yoshihito Suzuki, Satoko Uemura, Yuko Saito, Noboru Murofushi, Gregor Schmitz, Klaus Theres, Isomaro Yamaguchi
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  ABSTRACT: A novel tagging system AcREH, designed for obtaining gain-of-function mutations, was prepared on the basis of a self-stabilizing Ac transposon derivative. The transposable element, DsAT, was constructed in a way that it can activate transcription of neighboring genes by two 35S promoters and/or by four tandem repeats of the enhancer fragment of this promoter. DsAT revealed somatic excision in the first generation of the tobacco transformants. The element exhibited germinal excision to the next generation, as demonstrated by PCR and Southern hybridization analysis. In spite of the structure of the element, which may inhibit the expression of the transposase gene, the frequency of germinal excision was comparable to or higher than those so far reported, suggesting the applicability of the element for gene tagging.
  Plant Molecular Biology 12/2000; 45(2):123-131. · 4.15 Impact Factor
• Article: Photobleaching Activity of 2-(Phenylamino)methylidenecyclohexane-1,3-diones in Tobacco (Nicotiana tabacum) Cultured Cells

  Jing-Ming Wang, Tadao Asami, Fan-Sik Che, Noboru Murofushi, Shigeo Yoshida
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  ABSTRACT: A series of phenylalkylidenecyclohexane-1,3-dione derivatives were designed and synthesized as vinylogous analogs of phthalimides, which are known photobleaching herbicides. The bleaching activity of synthesized compounds was assayed with photomixotrophic tobacco cultured cells under either light or dark conditions. Both the chlorophyll and the carotenoid contents of the cells treated with the cyclic diones decreased to almost zero within 24 h under the light condition but not under the dark condition. This rapid emergence of bleaching activity with light is one of the most distinctive actions of Protox-inhibiting herbicides; however, the cyclic dione did not inhibit protoporphyrinogen oxidase in vitro. Thus, we concluded that the cyclic diones possessed a different herbicidal mode of action from Protox-inhibiting herbicide. Keywords: Photobleaching herbicide; tobacco cells; chlorophyll biosynthesis
  07/1997;
• Article: Molecular cloning and characterization of a cDNA encoding the gibberellin biosynthetic enzyme ent‐kaurene synthase B from pumpkin (Cucurbita maxima L.)

  Shinjiro Yamaguchi, Tamio Saito, Hiroshi Abe, Hisakazu Yamane, Noboru Murofushi, Yuji Kamiya
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  ABSTRACT: The first committed step in the formation of diterpenoids leading to gibberellin (GA) biosynthesis is the conversion of geranylgeranyl diphosphate (GGDP) to ent-kaurene. ent-Kaurene synthase A (KSA) catalyzes the conversion of GGDP to copalyl diphosphate (CDP), which is subsequently converted to ent-kaurene by ent-kaurene synthase B (KSB). A full-length KSB cDNA was isolated from developing cotyledons in immature seeds of pumpkin (Cucurbita maxima L.). Degenerate oligonucleotide primers were designed from the amino acid sequences obtained from the purified protein to amplify a cDNA fragment, which was used for library screening. The isolated full-length cDNA was expressed in Escherichia coli as a fusion protein, which demonstrated the KSB activity to cyclize [3H]CDP to [3H]ent-kaurene. The KSB transcript was most abundant in growing tissues, but was detected in every organ in pumpkin seedlings. The deduced amino acid sequence shares significant homology with other terpene cyclases, including the conserved DDXXD motif, a putative divalent metal ion-diphosphate complex binding site. A putative transit peptide sequence that may target the translated product into the plastids is present in the N-terminal region.
  The Plant Journal 07/1996; 10(2):203 - 213. · 6.16 Impact Factor
• Source

  Available from: rz.uni-karlsruhe.de

  Article: Phytochrome inhibits the effectiveness of gibberellins to induce cell elongation in rice

  Tomonobu Toyomasu, Hisazaku Yamane, Noboru Murofushi, Peter Nick
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  ABSTRACT: Red light controls cell elongation in seedlings of rice (Oryza sativa L.) in a far-red-reversible manner (Nick and Furuya, 1993, Plant Growth Regul. 12, 195–206). The role of gibberellins and microtubules in the transduction of this response was investigated in the rice cultivars Nihon Masari (japonica type) and Kasarath (indica type). The dose dependence of mesocotyl elongation on applied gibberellic acid (GA3) was shifted by red light, and this shift was reversed by far-red light. In contrast, coleoptile elongation was found to be independent of exogenous GA3. Nevertheless, it was inhibited by red light, and this inhibition was reversed by far-red light. The content of the active gibberellin species GA1 and GA4 was estimated by radio-immunoassay. In the mesocotyl, the gibberellin content per cell was found to increase after irradiation with red light, and this increase was far-red reversible. Conversely, the cellular gibberellin content in japonica-type coleoptiles did not exhibit any significant light response. Microtubules reoriented from transverse to longitudinal arrays in response to red light and this reorientation could be reversed by subsequent far-red light in both the coleoptile and the mesocotyl. This movement was accompanied by changes in cell-wall birefringence, indicating parallel reorientations of cellulose deposition. The data indicate that phytochrome regulates the sensitivity of the tissue towards gibberellins, that gibberellin synthesis is controlled in a negative-feedback loop dependent on gibberellin effectiveness, and that at least two hormone-triggered signal chains are linked to the cytoskeleton in rice.
  Planta 06/1994; 194(2):256-263. · 3.00 Impact Factor
• Article: Endogenous gibberellins in clover broomrape, a parasitic plant, and its host, clover: Dependency of the parasite on the host for gibberellin production

  Yoshihito Suzuki, Noboru Murofushi, Yun-Hui Zhang, Yasutomo Takeuchi
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  ABSTRACT: Endogenous gibberellins were analyzed from a parasitic plant, clover broomrape (Orobanche minor Smith), and its host, clover (Trifolium repens L.). Members of both the early-13- and the early-non-hydroxylation pathways were identified from both the parasite and the host (GA12, GA24, GA9 GA4, GA44, GA19, GA20, and GA1 from clover broomrape; GA9, GA4, GA44, GA19, GA20, and GA1 from clover). Quantitative analyses showed that GA44 was present at high levels in both host and parasite. The similarity in the gibberellins suggests the possibility that the major gibberellins in clover broomrape are transported from clover. However gibberellins such as GA58, GA38, and notably GA47 which was identified from a plant for the first time were detected only from clover broomrape, suggesting that the parasite may have the ability to produce at least those gibberellins
  Journal of Plant Growth Regulation 04/1994; 13(2):63-67. · 2.86 Impact Factor
• Article: Biosynthesis of brassinolide from teasterone via typhasterol and castasterone in cultured cells of Catharanthus roseus

  Hiroyuki Suzuki, Shozo Fujioka, Suguru Takatsuto, Takao Yokota, Noboru Murofushi, Akira Sakurai
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  ABSTRACT: The biosynthesis of brassinolide (BL) in crown gall and nontransformed cells of Catharanthus roseus in which BL, castasterone (CS), typhasterol (TY), and teasterone (TE) are endogenous was investigated using deuterated TY and TE as substrates. The metabolites were analyzed by gas chromatography-mass spectrometry (GC-MS) and/or GC-selected ion monitoring (SIM). It was found that these cells converted TY to CS and BL, as well as TE to TY and CS. Because the pathway from CS to BL in the cells has already been confirmed, a biosynthetic sequence of TE → TY → CS → BL was established. Reversible conversion between TE and TY was observed.
  Journal of Plant Growth Regulation 04/1994; 13(1):21-26. · 2.86 Impact Factor
• Article: Qualitative and semi-quantitative analyses of cytokinins using LC/APCI-MS in combination with ELISA

  Young-Yell Yang, Isomaro Yamaguchi, Yoshiaki Kalo, Elmar W. Weiler, Noboru Murofushi, Nobutaka Takahashi
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  ABSTRACT: Application of liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC/APCI-MS) for the analysis of cytokinins was examined. The fragmentation of cytokinins was studied using authentic trans-zeatin (t-Z), trans-zeatin riboside (t-ZR), isopentenyl adenine (i6Ade), isopentenyl adenosine (i6Ado), benzyl adenine (BAde), benzyl adenosine (BAdo), and kinetin. These cytokinins were effectively ionized by APCI in aqueous acetonitrile. t-Z, i6Ade, BAde, and kinetin showed prominent quasi-molecular ions of [M + H]+, and ribosylcytokinins clearly showed both [M + H]+ and a characteristic fragment ion ([M + H-ribose]+), giving some information about their structures. The qualitative and semi-quantitative analyses of cytokinins by LC/APCI-MS were validated in combination with enzyme-linked immunosorbent assay (ELISA) through the analysis of t-ZR in the teratoma of Nicotiana tobacum. t-ZR was conclusively identified and a semi-quantitative estimate of its endogenous levels were provided by the combination of LC/APCI-MS and ELISA. The quantified values obtained by LC/ APCI-MS (single ion detection) and ELISA are in close agreement.
  Journal of Plant Growth Regulation 04/1993; 12(1):21-25. · 2.86 Impact Factor
• Article: Light effects on endogenous levels of gibberellins in photoblastic lettuce seeds

  Tomonobu Toyomasu, Hiroko Tsuji, Hisakazu Yamane, Masayoshi Nakayama, Isomaro Yamaguchi, Noboru Murofushi, Nobutaka Takahashi, Yasunori Inoue
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  ABSTRACT: Gibberellin A1 (GA1), 3-epi-GA1 GA17, GA19, GA20, and GA77 were identified by Kovats retention indices and full-scan mass spectra from gas chromatography-mass spectrometry analysis of a purified extract of mature seeds of photoblastic lettuce (Lactuca sativa L. cv. Grand Rapids). Non-13-hydroxylated GAs such as GA4 and GA9 were not detected even by highly sensitive radioimmunoassay. These results show that the major biosynthetic pathway of GAs in lettuce seeds is the early-13-hydroxylation pathway leading to GA1, which is suggested to be physiologically active in lettuce seed germination. Quantification of endogenous GAs in the lettuce seeds by gas chromatography-selected ion monitoring using deuterated GAs as internal standards indicated that the endogenous level of GA1 increased to a level about three times that of dark control 6 h after a brief red light irradiation, and that far-red light given after red light suppressed the effect of red light. The contents of GA20 and GA19 were not affected by the red light irradiation. Evidence is also presented that 3-epi-GA1 is a native GA in the lettuce seeds.
  Journal of Plant Growth Regulation 04/1993; 12(2):85-90. · 2.86 Impact Factor
• Article: Biosynthesis of brassinolide from castasterone in cultured cells of Catharanthus roseus

  Hiroyuki Suzuki, Shozo Fujioka, Suguru Takatsuto, Takao Yokota, Noboru Murofushi, Akira Sakurai
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  ABSTRACT: Feeding experiments with tritium- and deuterium-labeled castasterone (CS) were conducted with three cell lines of Catharanthus roseus, including crown gall cells and nontransformed cells. In all three cell lines, the conversion of CS to brassinolide (BL) was observed and unequivocally confirmed by gas chromatography/mass spectrometry (GC/MS). This is the first conclusive evidence that CS is the biosynthetic precursor of BL.
  Journal of Plant Growth Regulation 04/1993; 12(2):101-106. · 2.86 Impact Factor
• Article: Gibberellin biosynthetic pathway and the physiologically active gibberellin in the shoot ofCucumis sativus L.

  Masayoshi Nakayama, Hisakazu Yamane, Noboru Murofushi, Nobutaka Takahashi, Lewis N. Mander, Hideharu Seto
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  ABSTRACT: [2H2]Gibberellin A24 (GA24) and [2H4]-GA9 were applied to the apices of normal-type cucumber (Cucumis sativus L. cv. Yomaki) seedlings treated with uniconazole, an inhibitor of GA biosynthesis. The metabolites from these feeds were identified by full-scan gas chromatography-mass spectrometry (GC-MS) to confirm the conversions of [2H2]GA24 to [2H2]GA9 and of [2H4]GA9 to [2H4]GA4. The results show that GA4 is biosynthesized from GA24 via GA9. In a cucumber hypocotyl elongation bioassay using cv. Yomaki, prohexadione (DOCHC), an inhibitor of 2-oxoglutaratedependent dioxygenase, inhibited the hypocotyl elongation caused by application of GA9, while DOCHC enhanced the elongation caused by application of GA4. These results indicate that GA4 is a physiologically active GA and that the activity of GA9 is due to its conversion to GA4 in cucumber shoots.
  Journal of Plant Growth Regulation 04/1991; 10(1):115-119. · 2.86 Impact Factor
• Article: Quantitative changes of free-base, riboside, ribotide and glucoside cytokinins in developing rice grains

  Makiko Takagi, Takao Yokota, Noboru Murofushi, Hitoshi Saka, Nobutaka Takahashi
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  ABSTRACT: Rice grains at various growth stages were analysed for endogenous free-base, riboside, ribotide and glucoside cytokinins on the basis of GC/MS and GC/SIM using deuterium-labeled internal standards. Cytokinins identified were trans- and cis-zeatins, trans- and cis-ribosylzeatins, isopentenyladenosine, isopentenyladenosine monophosphate, trans- and cis-ribosylzeatin monophosphates, trans- and cis-zeatin-O-glucosides, trans- and cis-ribosylzeatin-O-glucosides and zeatin-9-glucoside (trans/cis geometry was not determined). The highest amounts of cytokinins were recorded at the early growth stage, namely either heading, anthesis or milk stage, suggesting that cytokinins may play important roles in the development of the grain. Cis isomers of zeatin derivatives were always present and more abundant than trans isomers. It seemed unlikely that cis isomers were released from t-RNAs during the extraction procedure.
  Plant Growth Regulation 11/1989; 8(4):349-364. · 1.60 Impact Factor
• Article: Endogenous gibberellins in the shoots of normal- and bush-type Cucumis sativus L.

  Masayoshi Nakayama, Hisakazu Yamane, Isomaro Yamaguchi, Noboru Murofushi, Nobutaka Takahashi, Masayuki Katsumi
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  ABSTRACT: Endogenous gibberellins (GAs) in the shoots of normal- (cv. Yomaki, YO) and bush-type (cv. Spacemaster, SP) cultivars of cucumber (Cucumis sativus L.) grown under natural conditions were analyzed. From both YO and SP grown for 40 days, after sowing, a series of C-13-H GAs including GA4, GA9, GA15, GA24, GA25, GA34, and GA51 were identified by gas chromatography-mass spectrometry (GC-MS; full scan). In addition to the above GAs, GA12 and GA70 were similarly identified from both YO and SP grown for 61 days after sowing. The endogenous levels of GA4 and GA9, which are highly active in promoting cucumber hypocotyl elongation, were quantified by GC-selected ion monitoring (GC-SIM) using [2H2]GA4 and [2H4]GA9 as internal standards. No remarkable difference in terms of endogenous levels of GA4/9 was observed between YO and SP in both growth stages (40 and 61 days after sowing).
  Journal of Plant Growth Regulation 08/1989; 8(3):237-247. · 2.86 Impact Factor
• Article: Concentrations ofent-kaurene and squalene in vegetative rice shoots

  Thomas C. Moore, Hisakazu Yamane, Noboru Murofushi, Nobutaka Takahashi
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  ABSTRACT: Ent-kaurene (ent-kaur-16-ene) and squalene were analyzed in extracts of the shoots of three cultivars of rice (Oryza sativa L.) of 14 and 28 days of age by gas chromatography-mass spectrometry (GS-MS) and GC-selected ion monitoring (GS-SIM).Ent-kaurene occurred at approximate concentrations of ent-kaurene than the other two cultivars at both developmental stages. The level ofent-kaurene in the dwarf cultivar Tan-ginbozu was similar to that in the normal cultivar Nihonbare at 14 days but was lower than in Nihonbare at 28 days. Trace amounts ofent-isokaurene (ent-kaur-15-ene) were also found in the extracts of all three cultivars of shoots at 28 days. Squalene occurred in approximate concentrations from as low as 19 ng/g f.w. in 28-day-old Waito-C shoots to as much as 626 ng/g f.w. in 14-day-old Nihonbare shoots. Both Tan-ginbozu and Waito-C shoots contained less squalene than Nihonbare shoots at both developmental stages.
  Journal of Plant Growth Regulation 01/1988; 7(3):145-151. · 2.86 Impact Factor
• Source

  Available from: Yoshihito Suzuki

  Article: Synthesis of Benzyl 6-O-D-apiofuranosyl-D-glucopyranoside, a Metabolite of Benzoic Acid in Lemna paucicostata

  Yoshihito Suzuki, Isomaro Yamaguchi, Noboru Murofushi, Nobutaka Takahashi, Fumio Sugawara, Shigeo Yoshida, Tomoo Nukada, Tomoya Ogawa
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  ABSTRACT: Benzyl 6-0-b-D-apiofuranosyl-b-D-glucopyranoside and benzyl 6-0-a-D-apiofuranosyl-b-D-glucopyranoside were synthesized to determine the stereoschemistry of the glycosidic bond of a metabolite of benzoic acid isolated from Lemnapaucicostata 151. Benzoic acid-related compoundsare known to possess flower-inducing activity toward the Lemna family.1~6) In the course of our in-vestigation of metabolism of benzoic acid in Lemna paucicostata 151, benzyl 6-0-d-apiofuranosyl-jS-D-glucopyranoside (1) was isolated as one of the metabolites of benzoic acid (manuscript in preparation). This con-version process is very interesting because it involved reducing a benzoyl group to a benzyl group, against the general remarks that the incorporated bioactive compounds are oxi-dized or simply conjugated. The linkage of this compound between the apiosyl residue and glucosyl residue could not be determined by a *H NMRanalysis, because no clear nu-clear Overhauser effect between HI and H2 of the apiosyl residue was observed, which is suggestive of a trans configuration, but not conclusive. In this paper, we report the un-ambiguous synthesis of 1 for determining the stereochemistry of the glycosidic linkage. There are two reports about syntheses of glycosides that have an apiosyl residue. Both of these glycosides, 4/-O-methylapiin7) and Minosa leaf Movement Factor I (M-LMFI),8) had a 2-O/J-D-apiofuranosylglycoside linkage. In the synthesis of 4/-O-methylapiin, the apiofuranosyl bromide was used as a glycosyl donor, but this bromide was unstable. So in the synthesis of M-LMFI, peracetylated apiose wasused. In this study, peracetylated apiose (2), methyl 2,3,3/-tri-0-acetyl-l-thio-apioside (3) and methyl 2,3-<9-isopropylidene-3/-0-acetyl-1-thio-apioside (9) were used as donors, and the products of these three reaction are compared. A readily available benzyl 2,3,4-tri-O-acetyl-/?-D-glucopyranoside (4) prepared from d-glucose in six steps (ll.6% overall yield)9'10) was served as a glycosyl acceptor. A mixture of l ,2,3,3 /-tetra-O-acetyl-jS-D-apiofuranose (2) and its a-anomer was prepared from d-mannose in 9 steps (9.1% overall yield),8'n) before being converted to methyl 2,3,3'-tri-(9-Fig. 1
  Agric. Biol. Chem. 01/1988; 52:1261-1266.
• Source

  Available from: Yoshihito Suzuki

  Article: Identification of Phenylglyoxal as a Flower-inducing Substance of Lemna from Pharbitis purpurea

  Yoshihito Suzuki, Isomaro Yamaguchi, Noboru Murofushi, Nobutaka Takahashi
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  ABSTRACT: 2-Hydroxy-l-phenyl-l,4-pentanedione (HPP) was isolated and identified from Pharbitis purpurea as a flower-inducing substance by using Lemnapaucicostata 151 as a bioassay plant. This compoundwas racemic and was found to be an artifact, which could be formed by condensation between acetone and phenylglyoxal. Phenylglyoxal was shown to be naturally occurring in P. purpurea and also had flowering activity. The activity of each compound was inhibited by GA3, ABAand IAA, and promoted by zeatin in L. paucicostata 151, as in the case ofbenzoic acid-related compounds. Numerousefforts have been madeto isolate the hormonal substances responsible for flow-er induction, but have so far yielded very little success. Onereason for this failure is the lack of a suitable bioassay system. Since Cleland et al. identified salicylic acid1} by using Lemna gibba L. G3, Lemna has been used as an assay plant, and some successful results to isolate flower-inducing substances have been achieved.2'3) In the present study, Lemna paucicostata 151, which is very sensitive to benzoic acid-related compounds, was used as an assay plant in our series of efforts to investigate flower-inducing compounds in Pharbitis. The survey of flower-inducing compounds in cotyledons of P. nil grown under short-day conditions (dark for 16hr and light for 8hr) showed the occurrence of an active compound with a relatively polar chromatographic be-havior (data not shown); while, in the surVey using extracts of immature seeds of P. pur-purea, flower-inducing activity was noticed in an w-butanol soluble fraction, which contained polar substances, that was obtained by solvent fractionation. Because of the material shortage of P. nil cotyledons, and based on the speculation that, 1013 since such Pharbitis plants as P. nil cv. Kidachi and cv. Violet flower with a single short-day treatment on their cotyledons, the well de-veloped cotyledons in late immature seeds of Pharbitis plants may already contain active compoundsthat are released from a storage site to induce flowering when they receive a short-day treatment after germination, we began with identifying the active compoundin immature seeds of P. purpurea. The immature seeds of P. purpurea (27kg fr. wt.) were extracted with aqueous acetone. Evaporation of the solvent gave an aqueous residue, which was extracted with benzene, ethyl acetate and ^-butanol. If the immature seeds of P. purpurea contained the active compound, which was detected from the cotyledon of P. nil, that compound was con-sidered to be extracted into the w-butanol fraction. The w-butanol extracts were concen-trated and subjected to charcoal chroma-tography, eluting with aqueous acetone (0~
  Agric. Biol. Chem. 01/1988; 52:1013-1019.
• Article: Identification of gibberellins in the rice plant and quantitative changes of gibberellin A19 throughout its life cycle

  Shin Kurogochi, Noboru Murofushi, Yasuo Ota, Nobutaka Takahashi
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  ABSTRACT: The major endogenous gibberellin (GA) in shoots, roots and ears of the rice plant, Oryza sativa L. japonica cv. Nihonbare, was identified as GA19 by combined gas liquid chromatography-mass spectrometry (GC-MS) and GC-selected ion current monitoring (GC-SICM). Another GA present in these tissues in small quantity was tentatively identified as GA1 by GC-SICM, and GA4 may be present in the seeds (kernels) of 3rd-leaf-stage seedlings. Using GC-SICM, the GA19 content was quantified throughout the life cycle of rice plants. It was found to reach high levels (ca. 10–15 g/kg fresh weight) in 3rd-leaf seedlings, at panicle initiation (shoots), and during heading and anthesis (ears). The levels of GA19 in Oryza sativa indica cv. T-136 underwent changes closely similar to those found in Nihonbare. The growth-promoting activity in rice of exogenous GA19 is generally considerably less than that of GA1. It therefore seems possible that GA19 functions as a pool GA. The level of active GAs such as GA1 may be regulated by the rate of biosynthesis of GA19 or its metabolic conversions.
  Planta 12/1978; 146(2):185-191. · 3.00 Impact Factor