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Naoki Asano - One of the best experts on this subject based on the ideXlab platform.

Atsushi Kato - One of the best experts on this subject based on the ideXlab platform.

  • isolation and sar studies of bicyclic iminosugars from Castanospermum Australe as glycosidase inhibitors
    Phytochemistry, 2015
    Co-Authors: Atsushi Kato, Jacqueline Hollinshead, Kyoko Kinami, Yutaro Tsuji, Shota Miyawaki, J L Kiappes, Yuki Hirokami, Isao Adachi, Robert J Nash, Nicole Zitzmann
    Abstract:

    We report the isolation and structural determination of fourteen iminosugars, containing five pyrrolizidines and five indolizidines, from Castanospermum Australe. The structure of a new alkaloid was elucidated by spectroscopic methods as 6,8-diepi-castanospermine (13). Our side-by-side comparison between bicyclic and corresponding monocyclic iminosugars revealed that inhibition potency and spectrum against each enzyme are clearly changed by their core structures. Castanospermine (10) and 1-deoxynojirimycin (DNJ) have a common d-gluco configuration, and they showed the expected similar inhibition potency and spectrum. In sharp contrast, 6-epi-castanospermine (12) and 1-deoxymannojirimycin (manno-DNJ) both have the d-manno configuration but the α-mannosidase inhibition of 6-epi-castanospermine (12) was much better than that of manno-DNJ. 6,8-Diepi-castanospermine (13) could be regarded as a bicyclic derivative of talo-DNJ, but it showed a complete loss of α-galactosidase A inhibition. This behavior against α-galactosidase A is similar to that observed for 1-epi-australine (6) and altro-DMDP.

  • isolation of the pyrrolizidine alkaloid 1 epialexine from Castanospermum Australe
    Phytochemistry Letters, 2010
    Co-Authors: Laurence Edmund Jones, Jacqueline Hollinshead, Sarah F Jenkinson, David J Watkin, George W J Fleet, Atsushi Kato, Amber L. Thompson, Robert J Nash
    Abstract:

    Abstract The Australian leguminous tree Castanospermum Australe contains the anti-viral glucose analogue indolizidine alkaloid castanospermine. As the result of a search for new bioactive carbohydrate-like compounds we now report the isolation of the novel polyhydroxylated pyrrolizidine alkaloid, 1-epialexine, from the leaves and stems of C. Australe. 1-Epialexine is a weak inhibitor of β-mannosidase from Cellullomonas fimi.

  • isolation of the pyrrolizidine alkaloid 1 epialexine from Castanospermum Australe
    Phytochemistry Letters, 2010
    Co-Authors: Laurence Edmund Jones, Jacqueline Hollinshead, Sarah F Jenkinson, David J Watkin, George W J Fleet, Atsushi Kato, Zoltan A Gal, Robert J Nash
    Abstract:

    Jones, L., Hollinshead, J., Fleet, G. W. J., Thompson, A. L., Watkin, D. J., Gal, Z. A., Jenkinson, S. F., Kato, A., Nash, R. J. (2010). Isolation of the pyrrolizidine alkaloid 1-epialexine from Castanospermum Australe.  Phytochemistry Letters, 3, 133-135 IMPF: 01.36

  • isolation of the pyrrolizidine alkaloid 1 epialexine from Castanospermum Australe
    Phytochemistry Letters, 2010
    Co-Authors: Laurence Edmund Jones, Jacqueline Hollinshead, Sarah F Jenkinson, David J Watkin, George W J Fleet, Atsushi Kato, Amber L. Thompson, Robert J Nash
    Abstract:

    Abstract The Australian leguminous tree Castanospermum Australe contains the anti-viral glucose analogue indolizidine alkaloid castanospermine. As the result of a search for new bioactive carbohydrate-like compounds we now report the isolation of the novel polyhydroxylated pyrrolizidine alkaloid, 1-epialexine, from the leaves and stems of C. Australe. 1-Epialexine is a weak inhibitor of β-mannosidase from Cellullomonas fimi.

  • Australine and related alkaloids: easy structural confirmation by 13C NMR spectral data and biological activities
    Tetrahedron-asymmetry, 2003
    Co-Authors: Atsushi Kato, Erika Kano, Isao Adachi, George W J Fleet, Russell J. Molyneux, Alison A Watson, Robert J Nash, Mark R. Wormald, Haruhisa Kizu, Kyoko Ikeda
    Abstract:

    Abstract The first polyhydroxylated pyrrolizidine alkaloid with a hydroxymethyl group at C-3 was isolated from pods of Alexa leiopetala (Leguminosae) and designated alexine 1. The Australian legume Castanospermum Australe is also known to produce the same structural type of pyrrolizidines. There are reports of the isolation of australine (7a-epi-alexine) 2, 1-epi-australine 3, 3-epi-australine 4, and 7-epi-australine 5 from this plant to date. Their unambiguous syntheses established that the natural product reported as 5 is 2 and the published NMR data for 2 are those of 3. These confusions prompted us to unambiguously confirm the structures and biological activities of australine isomers and related alkaloids. A careful search for polyhydroxylated pyrrolizidines in seeds of C. Australe led to the discovery of three new alkaloids, 2,3-diepi-australine 6, 2,3,7-triepi-australine 7, and the 2-O-β- d -glucopyranoside of 3 (8). Herein, we report the full 13C NMR assignment of alkaloids 1–8 and the glycosidase inhibitory activities of alkaloids 1–8 together with the highly oxygenated pyrrolizidine, casuarine 9, and its 6-O-α- d -glucopyranoside 10.

Hiroshi Nojima - One of the best experts on this subject based on the ideXlab platform.

Julien Delahaie - One of the best experts on this subject based on the ideXlab platform.

  • Comparaison moléculaire des graines orthodoxes de Medicago truncatula et récalcitrantes de Castanospermum Australe : une nouvelle approche pour comprendre l'acquisition de la tolérance à la dessiccation
    2013
    Co-Authors: Julien Delahaie
    Abstract:

    La tolérance à la dessiccation (TD) est définie comme l'aptitude à survivre à l'état sec et à reprendre un métabolisme normal après le retour à des conditions hydriques favorables. Contrairement aux graines orthodoxes, qui acquièrent la TD au cours de leur maturation, les graines récalcitrantes ne survivent pas à la dessiccation. L'analyse comparative du développement de ces deux types de graines constitue donc un modèle intéressant pour mettre en évidence des mécanismes spécifiquement impliqués dans la TD. Par des approches protéomique et transcriptomique, ce travail a permis de caractériser le développement de graines récalcitrantes de Castanospermum Australe et de le comparer à celui de graines orthodoxes de Medicago truncatula, espèce de la même sous-famille des Fabacées. Nos résultats montrent que certaines protéines de type LEA (Late Embryogenesis Abundant) sont absentes ou faiblement accumulées dans les graines matures de C. Australe comparé à celles de M. truncatula. Le profil des LEA ressemble à celui du mutant Mtabi3, déficient pour le régulateur majeur de la maturation des graines orthodoxes ABI3 (ABscissic acid Insensitive 3). L'analyse transcriptomique révèle une forte répression de CaABI3 et de ses gènes cibles en fin de développement chez les graines de C. Australe, alors qu'ils restent fortement exprimés tout au long de la maturation des graines de M. truncatula. Deux gènes codant pour ABI3 ont été clonés chez C. Australe : CaABI3 et CaABI3-like. Par sur-expression ectopique dans des racines de M. truncatula, seul CaABI3-like est en mesure d'activer les mêmes cibles que MtABI3. De plus, CaABI3 ne complémente pas le mutant abi3-5 d'Arabidopsis thaliana. Cette analyse renforce l'importance d'ABI3 pour expliquer la sensibilité à la TD des graines récalcitrantes. Elle révèle par ailleurs que la graine mature de C. Australe présente certaines caractéristiques d'une graine prête à germer tout en exprimant de nombreux gènes de réponse au stress.

  • lea polypeptide profiling of recalcitrant and orthodox legume seeds reveals abi3 regulated lea protein abundance linked to desiccation tolerance
    Journal of Experimental Botany, 2013
    Co-Authors: Julien Delahaie, Michaela Hundertmark, Jerome Bove, Olivier Leprince, Hélène Rogniaux, Julia Buitink
    Abstract:

    In contrast to orthodox seeds that acquire desiccation tolerance during maturation, recalcitrant seeds are unable to survive drying. These desiccation-sensitive seeds constitute an interesting model for comparative analysis with phylogenetically close species that are desiccation tolerant. Considering the importance of LEA (late embryogenesis abundant) proteins as protective molecules both in drought and in desiccation tolerance, the heat-stable proteome was characterized in cotyledons of the legume Castanospermum Australe and it was compared with that of the orthodox model legume Medicago truncatula. RNA sequencing identified transcripts of 16 homologues out of 17 LEA genes for which polypeptides are detected in M. truncatula seeds. It is shown that for 12 LEA genes, polypeptides were either absent or strongly reduced in C. Australe cotyledons compared with M. truncatula seeds. Instead, osmotically responsive, non-seed-specific dehydrins accumulated to high levels in the recalcitrant cotyledons compared with orthodox seeds. Next, M. truncatula mutants of the ABSCISIC ACID INSENSITIVE3 (ABI3) gene were characterized. Mature Mtabi3 seeds were found to be desiccation sensitive when dried below a critical water content of 0.4 g H2O g DW –1 . Characterization of the LEA proteome of the Mtabi3 seeds revealed a subset of LEA proteins with severely reduced abundance that were also found to be reduced or absent in C. Australe cotyledons. Transcripts of these genes were indeed shown to be ABI3 responsive. The results highlight those LEA proteins that are critical to desiccation tolerance and suggest that comparable regulatory pathways responsible for their accumulation are missing in both desiccationsensitive genotypes, revealing new insights into the mechanistic basis of the recalcitrant trait in seeds.

  • comparaison moleculaire des graines orthodoxes de medicago truncatula et recalcitrantes de Castanospermum Australe une nouvelle approche pour comprendre l acquisition de la tolerance a la dessiccation
    2013
    Co-Authors: Julien Delahaie
    Abstract:

    La tolerance a la dessiccation (TD) est definie comme l’aptitude a survivre a l’etat sec et a reprendre un metabolisme normal apres le retour a des conditions hydriques favorables. Contrairement aux graines orthodoxes, qui acquierent la TD au cours de leur maturation, les graines recalcitrantes ne survivent pas a la dessiccation. L’analyse comparative du developpement de ces deux types de graines constitue donc un modele interessant pour mettre en evidence des mecanismes specifiquement impliques dans la TD. Par des approches proteomique et transcriptomique, ce travail a permis de caracteriser le developpement de graines recalcitrantes de Castanospermum Australe et de le comparer a celui de graines orthodoxes de Medicago truncatula, espece de la meme sous-famille des Fabacees. Nos resultats montrent que certaines proteines de type LEA (Late Embryogenesis Abundant) sont absentes ou faiblement accumulees dans les graines matures de C. Australe compare a celles de M. Truncatula. Le profil des LEA ressemble a celui du mutant Mtabi3, deficient pour le regulateur majeur de la maturation des graines orthodoxes ABI3 (ABscissic acid Insensitive 3). L’analyse transcriptomique revele une forte repression de Ca ABI3 et de ses genes cibles en fin de developpement chez les graines de C. Australe, alors qu’ils restent fortement exprimes tout au long de la maturation des graines de M. Truncatula. Deux genes codant pour ABI3 ont ete clones chez C. Australe : CaABI3 et CaA BI-like. Par sur-expression ectopique dans des racines de M. Truncatula, seul CaABI3-like est en mesure d’activer les memes cibles que MtABI3. De plus, CaABI3 ne complemente pas le mutant abi3-5 d’ Arabidopsis thaliana. Cette analyse renforce l’importance d’ABI3 pour expliquer la sensibilite a la TD des graines recalcitrantes. Elle revele par ailleurs que la graine mature de C. Australe presente certaines caracteristiques d’une graine prete a germer tout en exprimant de nombreux genes de reponse au stress.

  • Comparaison moléculaire des graines orthodoxes de Medicago truncatula et récalcitrantes de Castanospermum Australe : une nouvelle approche pour comprendre l’acquisition de la tolérance à la dessiccation
    Université d'Angers, 2013
    Co-Authors: Julien Delahaie, Julia Buitink
    Abstract:

    Desiccation tolerance (DT) is defined as the ability to survive in the dry state and resume metabolic activity upon imbibition. Unlike orthodox seeds, that acquire DT during their maturation, recalcitrant seeds do not survive desiccation. A comparative analysis of orthodox and recalcitrant seeds development constitutes an interesting model to highlight mechanisms that are involved in DT. Using proteomic and transcriptomic analyses, the development of the recalcitrant Castanospermum Australe seeds was characterized and compared to development of orthodox Medicago truncatula seeds, species from the same sub-family of Fabaceae. Our results show that most LEA (Late Embryogenesis Abundant) proteins are absent or faintly accumulated in mature seeds of C. Australe compared to M. truncatula. The LEA protein profile is similar to seeds of the Mtabi3 mutant that is deficient in the expression of the major regulator of orthodox seed maturation ABI3 (ABscissic acid Insensitive 3). Transcriptome analysis reveals a strong repression of CaABI3 and its putative targets at the end of C. Australe seed development while the transcript levels of these target genes remain high until the end of maturation of M. truncatula seeds. Two genes coding for ABI3 were cloned in C. Australe: CaABI3 and CaABI3-like. Ectopic expression in M. truncatula roots demonstrated that only CaABI3-like is able to activate the same targets as MtABI3. Moreover, CaABI3 does not complement the abi3-5 mutant of Arabidopsis thaliana. This analysis strengthens the implication of ABI3 in the desiccation sensitivity of recalcitrant seeds. In addition, mature C. Australe seeds display certain characteristics of a seed that is preparing for germination and express many stress response genes

  • Characterization of a recalcitrant legume seed towards a better understanding of desiccation tolerance mechanisms
    2012
    Co-Authors: Julien Delahaie, Michaela Hundertmark, Olivier Leprince, Julia Buitink, X. Deguercy, J. Bove
    Abstract:

    Castanospermum Australe is a tree species from the Fabaceae family, native to Australia but now found in as an ornamental in countries such as South Africa and USA. Its seeds are recalcitrant and, it is phylogenetically the closest recalcitrant species to Medicago truncatula, one of the genomic and genetic models of the Fabaceae. The latter species produces seeds that are orthodox and its seed development is well characterized at the molecular level by our group. Our objective is to identify genes and molecules involved in desiccation tolerance on the basis of their differential expression/accumulation between seeds of these two species. This comparative analysis first requires the physiological and molecular characterization of C. Australe recalcitrant seeds.

Yoshitaka Sugihara - One of the best experts on this subject based on the ideXlab platform.