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Hebestreit, Johann Philipp – One of the best experts on this subject based on the ideXlab platform.

  • Untersuchungen zum Synergismus von Saponinen und Toxinen bei in vitro kultivierten Säugetierzellen
    Humboldt-Universität zu Berlin Mathematisch-Naturwissenschaftliche Fakultät I, 2005
    Co-Authors: Hebestreit, Johann Philipp

    Abstract:

    Im Verlauf der Untersuchungen von Agrostemma Githago L. var. Githago, eines bekannten giftigen Vertreters der Caryophyllaceae, verwendeten wir neben Agrostemmasaponin das Saponinum album aus Gypsophila paniculata L., ebenfalls mit Gypsogenin (3b-Hydroxy-Olean-12-en-23-al-28-Säure) als Aglykon. Eine Kombination dieser Saponinderivate (3 µg/ml) mit einer Formylfunktion an Position C4 des Aglykons in Kombination mit RIPs und anderen natürlichen Toxinen zeigte eine kooperative Toxizität an ECV 304-Zellen. Ribosomen-inaktivierende Proteine (RIPs; EC Nr. 3.2.2.22) sind eine heterogene Familie von strukturell und evolutionsbedingt ähnlichen Proteinen mit einer katalytischen Domäne, die einen spezifischen Adeninrest enzymatisch von einer definierten Position der rRNA prokaryotischer und eukaryotischer Ribosomen zu entfernen vermag. Die kombinierte Verabreichung von subtoxischen Konzentrationen eines RIP-Typ 1 und des Saponins zeigte in dieser Studie einen spezifischen und zum ersten Mal größeren zytotoxischen Effekt auf Tumorzellen im Vergleich mit natürlichem Diphtheriatoxin. Es wird ein analoger, synergistischer Wirkungsmechanismus zwischen der durch Gypsophilasaponin induzierten Toxizität von Agrostin aus Agrostemma Githago L. und von Saporin aus Saponaria officinalis L. bzw. dem rekombinant hergestellten his-Saporin diskutiert. Offensichtlich nutzen diese aus den Samen der Caryophyllaceae isolierten Proteine einen ähnlichen Weg, um die Zellmembran zu passieren, was auf den Abwehrmechanismus dieser Pflanzen gegen pathogene Organismen schließen lässt.In the course of our investigation of Agrostemma Githago L. var. Githago, a well-known toxic member of the Caryophyllaceae family, we tested Saponinum album from Gypsophila paniculata L., both saponins with gypsogenin (3b-hydroxy-olean-12-en-23-al-28-oic acid) as aglycone. A combination of these particular saponin derivatives with a formyl function in triterpene position 4 (3 µg/ml) together with RIPs and other natural toxins revealed a co-operative toxicity against ECV 304-cells. Ribosome-inactivating proteins (RIPs; EC No. 3.2.2.22) are a heterogeneous family of structurally and evolutionary related plant proteins. They share a common functional domain capable of catalytically removing a specific adenine residue from a highly conserved, surface-exposed stem-loop structure in the large rRNA of prokaryotic and eukaryotic ribosomes. The combined administration of individually non-toxic concentrations of a RIP type 1 and a saponin presented in this study leads to a potent and for the first time greater specifically cytotoxic effect on tumor cells in comparison with natural diphtheria toxin. An analogy could be drawn between the observed induction of RIP-toxicity of Agrostin and of Saporin/ genetically engineered his-Saporin from Saponaria officinalis L. in combination with Gypsophilasaponin. Obviously these proteins, both obtained from the seeds of Caryophyllaceae species, use a similar mechanism to penetrate through the cell membrane in vitro suggesting a similar defence mechanism of these plants against pathogenic organisms

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Ingolf Schuphan – One of the best experts on this subject based on the ideXlab platform.

  • Metabolism of the nonylphenol isomer [ring-U-14C]-4-(3′,5′-dimethyl-3′-heptyl)-phenol by cell suspension cultures of Agrostemma Githago and soybean.
    Journal of Environmental Science and Health Part B, 2004
    Co-Authors: Burkhard Schmidt, Hildegard Patti, Gregor Hommes, Ingolf Schuphan

    Abstract:

    Abstract The biotransformation of the nonylphenol isomer [ring-U-14C]-4-(3′,5′-dimethyl-3′-heptyl)-phenol (4-353-NP, consisting of two diastereomers) was studied in soybean and Agrostemma Githago cell suspension cultures. With the A. Githago cells, a batch two-liquid-phase system (medium/n-hexadecane 200:1, v/v) was used, in order to produce higher concentrations and amounts of 4-353-NP metabolites for their identification; 4-353-NP was applied via the n-hexadecane phase. Initial concentrations of [14C]-4-353-NP were 1 mg L−1 (soybean), and 5 and 10 mg L−1 (A. Githago). After 2 (soybean) and 7 days (A. Githago) of incubation, the applied 4-353-NP was transformed almost completely by both plant species to four types of products: glycosides of parent 4-353-NP, glycosides of primary 4-353-NP metabolites, nonextractable residues and unknown, possibly polymeric materials detected in the media. The latter two products emerged especially in soybean cultures. Portions of primary metabolites amounted to 19–22% (so…

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  • Biotransformation of [ring-U-14C]4-n-nonylphenol by Agrostemma Githago cell culture in a two-liquid-phase system.
    Biotechnology Letters, 2003
    Co-Authors: Burkhard Schmidt, Hildegard Patti, Claudia Niewersch, Ingolf Schuphan

    Abstract:

    The biotransformation of [14C]4-n-nonylphenol (5 mg l−1; 10 mg l−1) by Agrostemma Githago cell suspensions was studied using a batch two-liquid-phase system (medium/n-hexadecane 200:1, v/v). The highly lipophilic 4-n-nonylphenol was applied vian-hexadecane phase. After 7 d of incubation, more than 85% of applied 4-n-nonylphenol was absorbed by the cells, and 40% was transformed to 10 side-chain monohydroxylated metabolites (two with additional double bond at side-chain). The primary metabolites were analyzed by GC-EIMS. In the cells, the monohydroxylated products and residual 4-n-nonylphenol were present as glycosides. The method proved to be suitable for the production of primary metabolites of 4-n-nonylphenol on a larger scale for identification purposes and for metabolic profiling of the compound.

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D. Bernhardt – One of the best experts on this subject based on the ideXlab platform.

  • A comparison of the synthesis of DNA, RNA and proteins in the embryos of after-ripened and thermo- or FR-dormant Agrostemma Githago L. seeds
    Seed Science Research, 1995
    Co-Authors: U. Gerth, D. Bernhardt

    Abstract:

    Imbibed embryos of after-ripened and secondarily thermo- and FR-dormant Agrostemma Githago seeds were investigated as to their ability to synthesize DNA, RNA and proteins with the aim of finding characteristic differences connected with the induction and maintenance of developmental arrest. A gradual decrease in DNA synthesis was observed during the induction of thermodormancy. However, DNA synthesis was stimulated up to that of embryos of 30–h-imbibed after-ripened seeds within 24 h approximately after transferring the thermodormant seeds into temperatures which normally allow germination. DNA synthesis of embryos of FR-dormant seeds remained constant at a relatively low level during 7 d FR and another 7 d dark incubation. RNA synthesis decreased to different extents during induction of thermo- and FR-dormancy when it was arrested at a relatively low level in seeds transferred to temperatures which normally allow germination. Processes leading to an increase in RNA synthesis such as in embryos of after-ripened seeds appeared to be quantitatively and/or qualitatively repressed. Interestingly, protein synthesis was extremely depressed during induction of thermodormancy whereas it was slightly stimulated during induction of FR-dormancy. Nevertheless two-dimensional protein PAGE revealed several polypeptides which were new, increased, decreased or not synthesized predominantly in axes of thermo- and FR-dormant seeds in comparison to germinating after-ripened seeds. It is suggested that a connection exists between these polypeptides and the repression of germination. After transferring seconarily dormant seeds to temperatures which normally allow germination, a temporary stimulation of protein synthesis could be observed in both cases.

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  • Changes in the synthesis of some proteins during breaking of secondarily induced thermodormancy by respiration inhibitors (cyanide, azide) and BAP in embryos of Agrostemma Githago L. seeds
    Seed Science Research, 1994
    Co-Authors: D. Bernhardt, U. Gerth

    Abstract:

    Secondary dormancy (thermodormancy) in Agrostemma Githago L. seeds, caused by imbibing the seeds for 4 d at 35°C in the dark, is broken under the influence of cyanide (10 mM), azide (1 mM or BAP (0.44 mM). Both respiration inhibitors (cyanide and azide) and BAP increase the synthesis of five specific soluble proteins in the embryo axes and cotyledons. The activity of β-cyanoalanine synthase (β-CAS, EC 4.4.1.9.), which is able to detoxify cyanide, decreased in response to cyanide and azide. The relevance of these findings to the breaking of thermodormancy is discussed.

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  • Synthesis of DNA and the Development of Amylase and Phosphatase Activities in Cotyledons of Germinating Seeds of Vaccaria pyramidata
    Journal of Experimental Botany, 1993
    Co-Authors: D. Bernhardt, A. Trutwig, A. Barkhold

    Abstract:

    As in cotyledons of Agrostemma Githago, synthesis of DNA takes place after germination in cotyledons of Vaccaria pyramidata and is followed by the formation of hydrolases, in particular, a-amylase and acid phosphatase. If DNA synthesis is inhibited by hydroxyurea, no, or only slight, enzyme activity develops. The possible role of this DNA synthesis is discussed.

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