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…
Krafczyk, N.; Heinrich, T.; Porzel, A.; Glomb, M. A.;Oxidation of the Dihydrochalcone Aspalathin Leads to DimerizationJ. Agr. Food Chem.576838-6843(2009)DOI: 10.1021/jf901614y
Aspalathin and nothofagin are typical ingredients of unfermented rooibos (Krafczyk, N.; Glomb, M. A. J. Agric. Food Chem.2008, 56, 3368). During oxidation these dihydrochalcones were degraded to higher molecular weight browning products under aerated and nonenzymatic conditions. In the early stages of browning reactions aspalathin formed two dimers. These two compounds were unequivocally established as atropisomers stemming from oxidative A to B ring coupling. Multilayer countercurrent chromatography (MLCCC) and preparative high-performance liquid chromatography (HPLC) were applied to obtain pure substances. The purity and identity of isolated dimers were confirmed by different NMR experiments, HPLC-DAD-MS, and HR-MS. In parallel to the formation of chromophores during the fermentation of black tea, the formation of aspalathin dimers implies an important mechanistic channel for the generation of color during the processing of rooibos.