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Alkaloid Synthesis

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Mauri Lounasmaa – One of the best experts on this subject based on the ideXlab platform.

  • Feeding experiments using suspension cultures of Atropa belladonna; limiting steps in the bioSynthesis of tropane Alkaloids
    Phytochemistry, 2001
    Co-Authors: Liisa Kaarina Simola, Riitta Parviainen, Aarne Martinsen, Aarre Huhtikangas, Reija Jokelat, Mauri Lounasmaa
    Abstract:

    Abstract Relatively low levels of tropane Alkaloid precursors (tropic acid, tropinone and tropanol) and Alkaloids (hyoscyamine and scopolamine) were fed to suspension cultures of Atropa belladonna with repressed Alkaloid Synthesis to study the transport of these compounds into the cells, to detect possible limiting steps in the biosynthetic pathway and to find ways of stimulating Alkaloid production. At the end of the experiments, the cell levels of tropic acid and tropinone had reached the initial nutrient medium concentrations, while cell levels of tropanol, hyoscyamine and scopolamine were high, suggesting an active uptake mechanism. Increased intracellular precursor levels did not forward the bioSynthesis of the tropane Alkaloids.

David Ohagan – One of the best experts on this subject based on the ideXlab platform.

  • elicitation of tropane Alkaloid bioSynthesis in transformed root cultures of datura stramonium
    Phytochemistry, 1999
    Co-Authors: Ioannis Zabetakis, Robert Edwards, David Ohagan
    Abstract:

    Abstract Hairy root cultures of Datura stramonium were treated with methyl jasmonate (MeJa), a cell wall preparation from baker’s yeast and oligogalacturonides, respectively, and analysed for the accumulation of the tropane Alkaloids, littorine, hyoscyamine and scopolamine, and their precursors, phenyllactate and tropine. The treatments increased Alkaloid accumulation in the order MeJa>fungal elicitor>oligogalacturonide and, in all cases, this was associated with an increase in tropine but a decline in phenyllactate concentrations. Time–course studies following MeJa treatments confirmed that increased tropane Alkaloid Synthesis was due to the differential enhancement of tropine bioSynthesis.

Felipe Vázquez-flota – One of the best experts on this subject based on the ideXlab platform.

  • Alkaloid Synthesis is coupled to shoot morphogenesis in Argemone mexicana L. (Papaveraceae) in vitro cultures
    In Vitro Cellular & Developmental Biology – Plant, 2019
    Co-Authors: Miriam Monforte-gonzález, J. Germán Serrano-gamboa, Cecilia Guízar-gonzález, M. L. Miranda-ham, Felipe Vázquez-flota
    Abstract:

    During the induction process of an in vitro callus culture of Argemone mexicana L. (Papaveraceae), the levels of two benzylisoquinoline Alkaloids known as berberine and sanguinarine displayed opposing trends. While the berberine levels steadily decreased from the initial explant stage up to the early proliferation of unorganized parenchymatous cell masses, the sanguinarine content increased. Once the callus culture was established, sanguinarine was the primary Alkaloid present and berberine could no longer be detected. However, upon shoot regeneration, the berberine accumulation recovered, but sanguinarine was found in the newly formed leafy tissue. After root formation, sanguinarine was relocated to this organ, whereas berberine was evenly distributed between both tissues. Explants from stem internodes did not form callus, and berberine—plus sanguinarine—containing axillary shoots emerged from lateral buds in the induction medium. In contrast to callus-derived shoots, no root formation was observed. Therefore, Alkaloid Synthesis in A. mexicana in vitro cultures is related to the level of tissue organization in different ways, and while berberine accumulation seems to require the presence of differentiated organs, this is not the case for sanguinarine. Moreover, leafy parts of rootless shoots acquired the capacity to accumulate sanguinarine, which is usually absent in aerial tissues of mature plants. However, when these shoots were rooted, sanguinarine was mainly located in the newly formed roots, while berberine was detected in the shoots at similar levels found in the roots.

  • Alkaloid metabolism in wounded Catharanthus roseus seedlings.
    Plant physiology and biochemistry : PPB, 2004
    Co-Authors: Felipe Vázquez-flota, Mildred Carrillo-pech, Yereni Minero-garcía, María De Lourdes Miranda-ham
    Abstract:

    The effect of mechanical wounding on Alkaloid metabolism was analyzed in Catharanthus roseus seedlings. Wounding induced an increase in ajmalicine accumulation, whereas catharanthine remained unaffected. A positive dual effect on vindoline was noticed. Short and mid-term effects were detected between 12 and 24 h after mechanical damage was inflicted, and apparently resulted from the accelerated transformation of the tabersonine intermediaries to vindoline. Long-term effects involved a generalized increase in carbon flux towards Alkaloid Synthesis. Exposure to ethylene (1 ppm) produced similar results to those observed in wounded seedlings, suggesting that it might be mediating the wound-induced increase in Alkaloid Synthesis. No synergistic or additive effects were observed when wounded seedlings were exposed to ethylene or jasmonate.

Liisa Kaarina Simola – One of the best experts on this subject based on the ideXlab platform.

  • Feeding experiments using suspension cultures of Atropa belladonna; limiting steps in the bioSynthesis of tropane Alkaloids
    Phytochemistry, 2001
    Co-Authors: Liisa Kaarina Simola, Riitta Parviainen, Aarne Martinsen, Aarre Huhtikangas, Reija Jokelat, Mauri Lounasmaa
    Abstract:

    Abstract Relatively low levels of tropane Alkaloid precursors (tropic acid, tropinone and tropanol) and Alkaloids (hyoscyamine and scopolamine) were fed to suspension cultures of Atropa belladonna with repressed Alkaloid Synthesis to study the transport of these compounds into the cells, to detect possible limiting steps in the biosynthetic pathway and to find ways of stimulating Alkaloid production. At the end of the experiments, the cell levels of tropic acid and tropinone had reached the initial nutrient medium concentrations, while cell levels of tropanol, hyoscyamine and scopolamine were high, suggesting an active uptake mechanism. Increased intracellular precursor levels did not forward the bioSynthesis of the tropane Alkaloids.

Paul Tudzynski – One of the best experts on this subject based on the ideXlab platform.

  • Identification of genes induced in Alkaloid-producing cultures of Claviceps sp.
    Current genetics, 1997
    Co-Authors: Claudia Arntz, Paul Tudzynski
    Abstract:

    In order to identify genes which are expressed during Alkaloid Synthesis in an axenic culture of Claviceps sp. (strain ATCC 26245), a cDNA library from a producing culture was differentially screened with cDNA from producing (cDNA+) and non-producing (cDNA-) cultures, respectively. Altogether, ten cDNA clones were obtained, the AlkaloidSynthesis-correlated expression of which was confirmed by Northern analyses. Evaluation of their nucleotide and derived amino-acid sequences identified one gene unequivocally, coding for dimethylallyltryptophan-synthase (DMAT-S), the initial enzyme of the specific Alkaloid pathway. For two other genes significant homologies to known fungal genes were detected: one clone showed homology to the Neurospora crassa ccg1 gene, coding for a clock-regulated putative general stress protein; seven cDNA clones, derived from the same gene, which is highly expressed under these conditions, contained typical hydrophobin domains and long stretches of asparagine/glycine repeats (like QID3 from Trichoderma harzianum), thus probably representing a cell-wall constituent. These data show that this is not only a successful approach to clone genes specific for the Alkaloid-pathway of C. purpurea, but also of genes which might be involved in the differentiation of sclerotial hyphae, the prerequisite for Alkaloid Synthesis.