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…
Jasmonates are signals in plant stress responses and development. The exact mode of their action is still controversial. To modulate jasmonate levels intracellularly as well as compartment-specifically, transgenic Nicotiana tabacum plants expressing single-chain antibodies selected against the naturally occurring (3R,7R)-enantiomer of jasmonic acid (JA) were created in the cytosol and the endoplasmic reticulum. Consequently, the expression of anti-JA antibodies in planta caused JA-deficient phenotypes such as insensitivity of germinating transgenic seedlings towards methyl jasmonate and the loss of wound-induced gene expression. Results presented here suggest an essential role for cytosolic JA in the wound response of tobacco plants. The findings support the view that substrate availability takes part in regulating JA biosynthesis upon wounding. Moreover, high JA levels observed in immunomodulated plants in response to wounding suggest that tobacco plants are able to perceive a reduced level of physiologically active JA and attempt to compensate for this by increased JA accumulation.
Publikation
Rivera, D. G.; Pando, O.; Suardiaz, R.; Coll, F.;Studies on the regioselectivity of the Baeyer-Villiger reaction of 3-keto steroids: Conformational effects determine the migration aptitudeSteroids72466-473(2007)DOI: 10.1016/j.steroids.2007.01.002
A detailed study of the Baeyer-Villiger reaction of 3-ketosteroids has been performed by using m-chloroperoxybenzoic and trifluoroperoxyacetic acids as oxidants. The process was fully regiospecific for 3-keto-5α-steroids with the employ of both peracids, and only partially regioselective for 3-keto-5β-steroids by using trifluoroperoxyacetic acid. Interestingly, the reaction resulted completely unselective for 3-keto-5β-steroids by using m-chloroperoxybenzoic acid. Theoretical studies were performed to explain the regiochemistry of this process, which is suggested to be controlled by conformational effects in the transition state of the Criegee rearrangement.