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…
An ancient reaction vessel: TobZ carbamoylates the antibiotic tobramycin to form nebramycin 5′. The YrdC‐like domain (blue) catalyzes the formation of the novel intermediate carbamoyladenylate, which is channeled through a common “reaction chamber” to the Kae1‐like domain (brown), site of carbamoyl transfer.
Publikation
van Berkel, S. S.; Brauch, S.; Gabriel, L.; Henze, M.; Stark, S.; Vasilev, D.; Wessjohann, L. A.; Abbas, M.; Westermann, B.;Traceless Tosylhydrazone-Based Triazole Formation: A Metal-Free Alternative to Strain-Promoted Azide-Alkyne CycloadditionAngew. Chem. Int. Ed.515343-5346(2012)DOI: 10.1002/anie.201108850
Triple‐T trick! Traceless tosylhydrazone‐based triazole formation is readily achieved by reacting primary amines with functional α,α‐dichlorotosylhydrozones under ambient conditions. This fast and efficient alternative affords exclusively 1,4‐substituted triazole “click products” with complete retention of configuration. Primary amines, inherent to many natural products, can be modified in this way without protecting group manipulations.
Publikation
Thomsen, H.; Reider, K.; Franke, K.; Wessjohann, L. A.; Keiser, J.; Dagne, E.; Arnold, N.;Characterization of Constituents and Anthelmintic Properties of Hagenia abyssinicaSci. Pharm.80433-446(2012)DOI: 10.3797/scipharm.1109-04
The dried female flowers of Hagenia abyssinica (Bruce) J. F. Gmel. (Rosaceae) are traditionally used as an anthelmintic remedy in Ethiopia and formerly were incorporated into the European Pharmacopoeia. One-, two- and tricyclic phloroglucinol derivatives (kosins) were suggested to be the active principles. However, polar constituents may also contribute to the activity. Therefore, we investigated for the first time the polar constituents. We isolated typical Rosaceae constituents such as quercetin 3-O-β-glucuronide, quercetin 3-O-β-glucoside and rutin. Polar kosin glycosides or derivatives could not be detected.The anthelmintic activity of fractions of different polarity were tested against the blood fluke Schistosoma mansoni, the liver flukes Clonorchis sinensis and Fasciola hepatica and the intestinal fluke Echinostoma caproni. The anthelmintic activity decreased with increasing polarity of the tested fractions. ESI-MS investigations indicated the predominant occurrence of kosins in the active fractions.Using the anthelmintic active extracts of Hagenia abyssinica we developed a simple, inexpensive bioassay against the non-parasitic nematode Caenorhabditis elegans, which can be used as an initial screening procedure for anthelmintic properties of crude extracts of plants or fungi. The anthelmintic activity of test extracts against the model organism was determined in a microtiter plate assay by enumeration of living and dead nematodes under a microscope.