Unser 10. Leibniz Plant Biochemistry Symposium am 7. und 8. Mai war ein großer Erfolg. Thematisch ging es in diesem Jahr um neue Methoden und Forschungsansätze der Naturstoffchemie. Die exzellenten Vorträge über Wirkstoffe…
Omanische Heilpflanze im Fokus der Phytochemie IPB-Wissenschaftler und Partner aus Dhofar haben jüngst die omanische Heilpflanze Terminalia dhofarica unter die phytochemische Lupe genommen. Die Pflanze ist reich an…
Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Using an improved purification and derivatization procedure, the endogenous gibberellin-O-glucosides in mature runner beans (Phaseolus coccineus) were analysed by combined gas chromatography-mass spectrometry. In addition to the previously characterized GA1-3-O-glucoside and GA8-2-O-glucoside, from runner beans, the following GA-O-glucosides were identified as endogenously occurring compounds by comparison of their full scan mass spectra and Kovats retention indices with those of standards: GA1-13-O-glucoside, 3-epiGA1-3-O-glucoside, GA5-13-O-glucoside and GA29-2-O-glucoside. The first three are reported in higher plants for the first time. The physiological relevance of the detected GA-O-glucosides is discussed.
Publikation
Maier, W.; Baumert, A.; Schumann, B.; Furukawa, H.; Gröger, D.;Synthesis of 1,3-dihydroxy-N-methylacridone and its conversion to rutacridone by cell-free extracts of Ruta graveolens cell culturesPhytochemistry32691-698(1993)DOI: 10.1016/S0031-9422(00)95155-0
Acridone synthase was isolated from cell suspension cultures of Ruta graveolens which catalysed the formation of 1,3-dihydroxy-N- methylacridone from N-methylanthraniloyl-CoA and malonyl-CoA. No cofactors were required for this enzyme reaction. Potassium phosphate buffer was superior compared to Tris-HCl. Sodium ascorbate instead of mercaptoethanol as oxidation protectant showed an advantageous effect on acridone synthase activity. The enzyme was strongly inhibited by 1,3-dihydroxy-N-methylacridone and by the antibiotic cerulenin. Microsomal preparations from Ruta graveolens cell suspension cultures catalysed an NADPH- and oxygen-dependent condensation of 1,3-dihydroxy-N- methylacridone and isopentenyl pyrophosphate. The reaction product was identified as rutacridone. Mg2+ or Mn2+ ions were necessary for optimal rutacridone synthase activity. The enzyme was inhibited by a number of inhibitors of cytochrome P-450 enzymes. A prenylated acridone, viz. glycocitrine-II was identified as an essential intermediate. Under in vivo conditions glycocitrine-II is incorporated into rutacridone, but a clear-cut conversion of glycocitrine-II by microsomal preparations (cyclase) was not observed. Microsomes converted rutacridone into furofoline-I. A number of detergents was used for solubilization of membrane-bound proteins of Ruta microsomes. Highest specific glycocitrine -II synthase (prenyltransferase) activity was obtained after solubilization with dodecylmaltoside.