The alkaloids of Amsinckia species: A. intermedia Fisch. & Mey., A. hispida (Ruiz. & Pav.) Johnst. and A. lycopsoides Lehm

Abstract

Hepatotoxic pyrrolizidine alkaloids have been isolated from Amsinckia species occurring in Victoria and in California. A. intermedia Fisch. & Mey. contains echumine and four new alkaloids, intermedine, lycopsamine, sincamidine, and an incompletely characterized alkaloid. The newly named alkaloids are retronecine esters of (+)-trachelanthic acid, (-)-viridifloric acid, and an isomer of heliotric acid, respectively. A. hispida (Ruiz. & Pav.) Johnst. and A. lycopsoides Lehm. contain intermedine, lycopsamine, and a minor amount of echiumine. N.m.r. data on intermedine, lycopsamine, and related alkaloids are included. Intermedine and lycopsamine have been prepared from the component amino alcohol and esterifying acids. These preparations constitute the first formal syntheses of hepatotoxic pyrrolizidine alkaloids.