An Evaluation of the Toxic Norditerpenoid Alkaloid Content Across <i>Delphinium</i> Species, and Their Acute Toxicities in a Murine Model

Larkspurs (Delphinium spp.) are one of the most problematic plants for cattle producers in North America. Previous research has shown that there is a difference in the alkaloid composition between different species of larkspurs, and between different populations of the same species. Differences in the chemical profiles of the various larkspurs and their associated toxicities in rodent models and in cattle have been documented. However, different methods were used to analyze the plant material and to characterize its toxicity. In this study, plant material from 20 larkspur collections was extracted using the same method and analyzed using the same liquid chromatography-mass spectrometry method, and the acute toxicity of each extract was tested using a mouse median lethal dose assay with the same strain of mice purchased from one vendor. The results from this study demonstrate the large variations in alkaloid composition and concentrations between the various species and populations of larkspurs in the western USA. The data also demonstrate a strong correlation between the N-(methylsuccinimido) anthranoyllycoctonine alkaloid content of the plant and its toxicity in a mouse model. The results from this study provide a standardized comparison of the risk of some of the more common and problematic larkspurs in the western USA.