Submitted to: Journal of Applied Toxicology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 24, 2010
Publication Date: January 31, 2011
Repository URL: http://onlinelibrary.wiley.com/doi/10.1002/jat.1563/pdf
Citation: Green, B.T., Welch, K.D., Gardner, D.R., Stegelmeier, B.L., Pfister, J.A., Cook, D., Davis, T.Z. 2011. A toxicokinetic comparison of norditerpenoid alkaloids from Delphinium barbeyi and D. glaucescens in cattle. Journal of Applied Toxicology. 31(1):20-6. DOI 10.1002/jat.1563. Interpretive Summary: Cattle are poisoned by toxic norditerpenoid alkaloids in Delphinium species (larkspur). D. glaucescens is an important toxic plant in Montana and Idaho, whereas D. barbeyi is a major toxic plant in Utah; their alkaloid profiles differ sufficiently to warrant investigation. This is important because an accurate assessment of risk is essential in formulating grazing strategies to avoid the poisoning of cattle on ranges where toxic larkspur grow. We determined the clearance times of serum alkaloids in steers dosed with larkspur from Montana to those dosed with larkspur from Utah in order to determine if the observed differences in toxicity between the two species of larkspur in cattle were due to differences in toxicokinetics. This study documented differences in toxicokinetics between the two species of larkspur. However, the results from this study support the recommendation that approximately seven days are required to clear 99% of the toxic alkaloids from the serum of animals administered either species of larkspur.
Technical Abstract: Cattle are poisoned by N-(methylsuccinimido) anthranoyllycoctonine type (MSAL-type) and 7,8-methylenedioxylycoctonine type (MDL-type) norditerpenoid alkaloids in Delphinium spp. Alkaloids in D. glaucescens are primarily of the MSAL-type, while D. barbeyi is a mixture of MSAL and MDL-types. The objectives of this study were to determine and compare the toxicokinetics of selected alkaloids from D. glaucescens and D. barbeyi in cattle. The two species of larkspur were dosed to three groups of Angus steers via oral gavage at doses of 8 mg/kg MSAL-type alkaloids for D. barbeyi and either 8.0 mg/kg, or 17.0 mg/kg MSAL-type alkaloids for D. glaucescens. In cattle dosed with D. barbeyi, serum deltaline (MDL-type) concentrations peaked at 488 ± 272 ng/ml at three hours and serum methyllycaconitine (MSAL-type) concentrations peaked at 831 ± 369 ng/ml at six hours. Deltaline was not detected in the serum of cattle dosed with D. glaucescens. Serum methyllycaconitine concentrations peaked at 497 ± 164 ng/ml at 18 hours, and 1089 ± 649 ng/ml at 24 hours for the 8 mg/kg and 17 mg/kg doses of D. glaucescens respectively. There were significant differences between the maximum serum concentrations and the area under the curve for the two doses of D. glaucescens but not D. barbeyi. Results from this experiment support the recommendation that approximately seven days are required to clear 99% of the toxic alkaloids from the serum of animals orally dosed with D. barbeyi or D. glaucescens, and that MDL-type alkaloids play an important role in the toxicity of Delphinium spp. in cattle.