Site of synthesis,metabolism and translocation of senecionine N-oxide in cultured roots of Senecio erucifolius |
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Authors: | Heiner Sander Thomas Hartmann |
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Institution: | (1) Institut für Pharmazeutische Biologie der Technischen, Universität Braunschweig, Mendelssohnstr. 1, D-3300 Braunschweig, FRG |
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Abstract: | Root cultures of Senecio erucifolius (Asteraceae) efficiently took up and incorporated 14C]putrescine and 14C]arginine into the pyrrolizidine alkaloid (PA) senecionine N-oxide. Pulse-chase experiments covering a growth period of 10 to 19 days revealed the absence of any significant alkaloid turnover. The only metabolic activity was a slow but progressive transformation of senecionine N-oxide into its dehydrogenation product, seneciphylline N-oxide. Tracer experiments with single roots showed that the sites of enhanced PA synthesis coincided with the sites of preferred protein synthesis, i.e. root apices, indicating a close correlation between growth activity and alkaloid synthesis. Long-term pulse-chase experiments (10 to 12 days) with 14C-labelled arginine, putrescine and senecionine fed to single roots indicated that in spite of its metabolic inertia, senecionine N-oxide is a mobile compound which is translocated into tissues newly grown during the chase.Dedicated to Dr. Friedrich Constabel on the occasion of his 60th birthday |
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Keywords: | alkaloid N-oxide (biosynthesis transport) pyrrolizidine alkaloid (turnover transformation) root culture (alkaloids) Senecio erucifolius |
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