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.
","abstract_html":"<p>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.</p> <p>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.</p> <p>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.</p>","abstract_has_math":false,"creators":["Sprengel, Merton E."],"institution":null,"degree_name":"Master of Science (MS)","degree_level":"Thesis","degree_discipline":"Chemistry","degree_department":null,"school":null,"contributors":["William D. Leech","Maurice E. Mathisen","George J. Nelson"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1966,"date_issued":"1966-08-01T07:00:00Z","date_published":"1966-08-01T07:00:00Z","updated_at":"2026-07-24T02:53:20Z","subjects":["Botany","Chemistry","Poisonous plants; Thistle"],"languages":["English"],"rights":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarsrepository.llu.edu/etd/933","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["William D. Leech","Maurice E. Mathisen","George J. Nelson"]},{"key":"dc:creator","label":"Author","values":["Sprengel, Merton E."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemistry"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science (MS)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Botany","Chemistry","Poisonous plants; Thistle"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]},{"key":"dc:rights","label":"Dc Rights","values":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarsrepository.llu.edu/etd/933"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["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.
"]},{"key":"dc:title","label":"Title","values":["Isolation of a Toxic Substance from CENTAUREA REPENS"]}]}],"canonical_facts":{"dc:contributor":["William D. Leech","Maurice E. Mathisen","George J. Nelson"],"dc:creator":["Sprengel, Merton E."],"dc:description.abstract":["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.
"],"dc:identifier":["https://scholarsrepository.llu.edu/etd/933"],"dc:language":["English"],"dc:rights":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."],"dc:subject":["Botany","Chemistry","Poisonous plants; Thistle"],"dc:title":["Isolation of a Toxic Substance from CENTAUREA REPENS"],"thesis:degree_discipline":["Chemistry"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["Master of Science (MS)"]},"updated_at":"2026-07-24T02:53:20Z"}