Isolation of a Toxic Substance from CENTAUREA REPENS
A poisonous steroid-type compound was isolated from Centaurea repens. After extraction with absolute ethanol, removal of the solvent, addition of 2% HCl to precipitate the pigments, and filtering, the pH was adjusted to 9 with aqueous anunonia. This solution was exhaustively extracted with chloroform, evaporated to dryness, and extracted with ethyl ether. This fraction was chromatographed on silica-gel plates, using 10:1 1,2-dichloroethane-methanol as the developer. The band at Rf 4.2 was removed and found toxic to mice. Labored, slow, gasping respiration and frequent involuntary muscular contractions became apparent within a few minutes following the intraperitoneal injection into each animal. Death resulted after sufficient dosages. Further separation was achieved by subjecting the Rf 0.42 toxic band to a second development in 55:6 1,2-dichloroethane-methanol. A compound appeared at Rf 0.54 which gave positive color tests for steroid structure with o-phosphoric acid, and 1:50:50 (w/v/v) vanillin-phosphoric acid-water reagents.
Botany, Chemistry, Poisonous plants; Thistle
Networked Digital Library of Theses and Dissertations