Centaurea

A natural substance of elemental composition Cis/Z/ Og was isolated from the plant Centaurea chilensis (Compositae). What is the structure and relative configuration of the substance given its H NMR spectrum 10 with (top) and without (bottom) deuterium exchange 10 ... 

A compound with the elemental composition C15//22O3 was isolated from the methanol extract of the Chilean medicinal plant Centaurea chilensis (Compositae)What is the structure of the natural product, given the NMR experiments 47 ... 

Inhibition of tomato and barley plants growing in soils infested with Centaurea repens (knapweed) was reported by Fletcher and Renney (38). A toxic component was isolated in highest concentration from the foliage of knapweed. The inhibitor was considered to be an indole alkaloid or auxin precursor because of its ultraviolet absorption spectrum and the positive reactions obtained with Salkowski and Ehrlich reagents. The presence of the inhibitor was considered to explain partially the rapid establishment of Centaura spp. in almost pure stands. 

Sesquiterpene Lactones and Allelochemicals from Centaurea Species... 

STEVENS AND MERRILL Centaurea Sesquiterpene Lactones and Allelochemicals 85... 

STEVENS and Merrill Centaurea Sesquiterpene Lactones and AUelochemicals 97... 

Offenbar die gleiche bei 51° schmelzende Verbindung konnte von Bohlmann und Herbst (40) auch aus den Wurzeln von Centaurea macrocephala Puschk. isoliert und in ihrer Konstitution durch Synthese gesichert werden (40). 

Die Vertreter der Gattung Centaurea L. enthalten bis auf die Sektion Centaurium als Hauptpolyin den Entetrainen-Kohlenwasserstoff, wah-rend in den Arten der Sektion Centaurium andere chromophore Systeme vorherrschen (59), (64). Zunachst sollen die Inhaltsstoffe von Centaurea ruthenica Lam. beschrieben werden, die der zuletzt erwahnten Sektion angehort. 

Die Verbindung CCIX kommt auch in den oberirdischen Teilen von Centaurea ruthenica Lam. vor. 

Bei einer umfassenden Untersuchung von etwa 50 Centaurea-Arten zeigte es sich, daB nur in drei Vertretem (Centaurea ruthenica Lam, C. tagana Brot. und C. alpina L.), alle aus der Sektion Centaurium, die oben besprochenen Polyine vorkommen. Samtliche anderen Vertreter enthalten als Hauptbestandteil das Entetrainen (XLIV) neben einer groBen Zahl anderer Polyine, die im nachsten Kapitel besprochen werden sollen. 

Lichtabsorption symmetrischer und unsymmetrischer Polyin-ene sowie Synthese eines Kohlenwasserstoffe aus Centaurea-Arten. Chem. Ber. 91, 1631 (1958). 

XXXII. Mitt. Ober weitere Polyine aus Centaurea ruthenica Lam. Chem. Ber. 94, 3179 (1961). 

It is also astonishing how the rich blue of a cornflower (Centaurea cyanus) and the majestic red flame of the com poppy (Papaver rheas) each derive from the same chromophore - again based on an anthrocyanidin. The pH of cornflower and poppy sap does not vary with soil composition, which explains why we see neither red cornflowers nor blue com poppies. 

Centaurea L. Chrysanthemum L. Cirsium Miller em. Scop. Coreopsis L. 

Atkinson, R. E. and R. F. Curtis Thiophene Derivatives from Centaurea and Rudh>eckia Spp. Tetrahedron Letters 1965, 297. 

Other phenolic compounds of commercial importance include the terpenoids, including mono, di, tri, and sesquiterpenes. While most of these are used as essential oils, fragrances, and flavors in various products, they are toxins in certain species. For example the sesquiterpene lactones of the Centaurea species cause an irreversible Parkinson s-like condition in horses called nigro-pallidal encephalomalacia. This is a lethal condition and the prognosis for recovery is grave in most cases, affected horses should be euthanized before reaching the terminal stages. 

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