Submitted to: Biochemical Systematics and Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 15, 2012
Publication Date: June 1, 2013
Citation: Colegate, S.M., Gardner, D.R., Davis, T.Z., Welsh, S.L., Betz, J.M., Panter, K.E. 2013. Identification of a lycopsamine-N-oxide chemotype of Amsinckia intermedia. Biochemical Systematics and Ecology. 48: 132-5. Interpretive Summary: Plant samples were collected from a rangeland site near Kingman Arizonia in February 2012 associated with apparent poisoning outbreak in cattle. The plants were identified as Amsinckia intermedia for which are known to contain hepatotoxic dehydropyrrolizidine alkaloids. Analysis were performed on plants collected from the Kingman site as well as from three sites near Washtucana Washington where the plants are not usually associated with livestock poisoning for comparison. Based on the analysis the Amsinckia plants from Arizona contained significant concentrations of the pyrrolizidine alkaloid identified as lycopsamine-N-oxide. The alkaloids content of the Kingman plants was unique in the relative high concentration of one alkaloid compared to plants collected from other sites or to that previously reported in the literature. Plants of this lycopsamine chemotype found near Kingman Arizona are thus expected to be toxic to grazing livestock and appropriate management recommendation should be followed to reduce exposure of livestock to the plant.
Technical Abstract: In February 2012, an apparent poisoning outbreak in cattle occurred on rangeland infested with Amsinckia intermedia near Kingman, Arizona. Plant samples were collected from the location every month from the time of the poisoning outbreak through to when the plant seeded and senesced in May 2012. Another collection was made in the vicinity of Kingman, of more vigorous plants growing in a nearby sand wash. For further comparative purposes, collections of flowering A. intermedia were made at three sites near Washtucna, Washington where the plants are not usually associated with livestock poisoning problems. All samples were analyzed using HPLC-MS/MS pyrrolizidine alkaloids. A. intermedia, collected at the site of the cattle intoxications, showed the major presence of lycopsamine -N-oxide. Also tentatively identified were acetyllycopsamine-N-oxide, echiumine-N-oxide, acetylechiumine-N-oxide, two putative dihydro analogues of lycopsamine-N-oxide and a putative deoxylycopsamine-N-oxide. The only free base observed in any significant amounts in the crude extract of the plant collected at this time was lycopsamine. The qualitative and quantitative HPLC-MS profiles of the flowering plants from each site in Washington were very similar to each other. In contrast to the Kingman, Arizona collections, the Washington plants showed a greater, and quantitatively more even, diversity of DHPA production. This present study identifies a lycopsamine /lycopsamine-N-oxide chemotype of A. intermedia, with no detectable intermedine. No other Amsinckia species, or populations of an Amsinckia species, have been similarly reported to produce such high relative levels of lycopsomine and/or it’s N-oxide. In this context plants of this lycopsamine chemotype of A. intermedia may be expected to be toxic to grazing livestock. Further research will be needed to confirm the possibility of livestock intoxication by this particular Amsinckia chemotype in comparison to the more usual chemotypes such as those from Washington.