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…
Winter, J.; Schneider, B.; Meyenburg, S.; Strack, D.; Adam, G.;Monitoring brassinosteroid biosynthetic enzymes by fluorescent tagging and HPLC analysis of their substrates and productsPhytochemistry51237-242(1999)DOI: 10.1016/S0031-9422(98)00760-2
Both the vicinal side chain hydroxyl groups and the 6-oxo function of brassinosteroids were modified by fluorescence tagging. Dansylaminophenylboronic acid was used as a derivatizing agent to form fluorescent esters of brassinosteroids containing a side-chain cis-diol structure. 6-Oxo type brassinosteroids were derivatized by means of dansylhydrazine. The modified brassinosteroids, as far as possible derivatized both at the diol and the oxo group, were separated by HPLC and the optimal emission wavelength was determined. By this approach almost all brassinosteroids, including biosynthetic precursors, were susceptible to highly sensitive analysis in the fmol range. This method has been verified as an analytical tool to determine brassinosteroids in cell culture extracts and to monitor brassinosteroid biosynthetic enzymes. 24-Epibrassinolide has been detected in tomato cell suspension cultures. Several steps of brassinosteroid biosynthesis, including the Baeyer–Villiger oxidation of 24-epicastasterone to give 24-epibrassinolide, were monitored in vitro with protein preparations of the same cell culture line.
Publikation
Vogt, T.; Ibdah, M.; Schmidt, J.; Wray, V.; Nimtz, M.; Strack, D.;Light-induced betacyanin and flavonol accumulation in bladder cells of Mesembryanthemum crystallinumPhytochemistry52583-592(1999)DOI: 10.1016/S0031-9422(99)00151-X
Treatment of the halophyte Mesembryanthemum crystallinum L. (ice plant) (Aizoaceae) with high intensities of white light resulted in a rapid cell-specific accumulation of betacyanins and flavonoids with 6-methoxyisorhamnetin 3-O-{[(2‴-E-feruloyl)-3‴-O-(β-d-glucopyranosyl)](2″-O-β-d-xylopyranosyl)}-β-d-glucopyranoside (mesembryanthin) as the predominant component, within bladder cells of the leaf epidermis. Induced accumulation of these metabolites was first detected 18 h after the initiation of light treatment in bladder cells located at the tip of young leaves followed by the bladder cells located on the epidermis of fully expanded leaves. UV-A light apparently is sufficient to induce accumulation of betacyanins and flavonoids. Application of 2-aminoindan 2-phosphonic acid, a specific inhibitor of phenylalanine ammonia-lyase (PAL; EC 4.3.1.5), not only inhibited the accumulation of flavonoids but also reduced betacyanin formation. Based on these observations we suggest these bladder cells as a model system to study regulation of betacyanin and flavonoid biosyntheses.
Publikation
Thuy, T. T.; Ripperger, H.; Porzel, A.; Sung, T. V.; Adam, G.;Counlarins, limonoids and an alkaloid from Clausena excavataPhytochemistry52511-516(1999)DOI: 10.1016/S0031-9422(99)00122-3
In addition to a known alkaloid, some limonoids and coumarins, the new coumarins excavatins A–M have been isolated from Clausena excavata. Their structures have been assigned by NMR and CD investigations.
Publikation
Thuy, T. T.; Porzel, A.; Ripperger, H.; Sung, T. V.; Adam, G.;Bishordeninyl terpene alkaloids from Zanthoxylum avicennaePhytochemistry50903-907(1999)DOI: 10.1016/S0031-9422(98)00612-8
In addition to (−)-culantraramine and (−)-culantraraminol the bishordeninyl terpene alkaloids, (−)-culantraramine N-oxide, (−)-culantraraminol N-oxide and avicennamine, have been isolated from the leaves of Zanthoxylum avicennae. Their structures have been assigned by MS and especially by NMR investigations.