Toxic pyrrolyzidine alkaloids from three mongolian plants. a possible risk for cattle poisoning.

Ten pyrrolizidine alkaloids (PA) were isolated from Senecio ambraceus, Senecio arcticus, and Nonea pulla growing on Mongolian pastures and meadows. Because of the contained toxic PA, these plants are suspected of causing cattle poisoning, which is reported in the literature and also in personal reports from local farmers and herdsmen. The structures of the PA were elucidated using spectroscopical methods. S. ambraceus contains the toxic PA senecionine, seneciphylline, and otosenine. In S. arcticus, senecionine can be found too, besides the non-toxic PA platyphylline, neoplatyphylline, and acetylplatyphylline. Nonea pulla is shown to contain the 0-7 isomers lycopsamine and intermedine as well as their 0-7-acetylderivatives. Besides the first mentioned acetylplatyphylline, all PA were already described in the literature.