A toxicokinetic comparison of norditerpenoid alkaloids from Delphinium barbeyi and D. glaucescens in cattle.

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⁻¹ MSAL-type alkaloids for D. barbeyi and either 8.0 or 17.0 mg kg⁻¹ MSAL-type alkaloids for D. glaucescens. In cattle dosed with D. barbeyi, serum deltaline (MDL-type) concentrations peaked at 488 ± 272 ng ml⁻¹ at 3 h and serum methyllycaconitine (MSAL-type) concentrations peaked at 831 ± 369 ng ml⁻¹ at 6 h. Deltaline was not detected in the serum of cattle dosed with D. glaucescens. Serum methyllycaconitine concentrations peaked at 497 ± 164 ng ml⁻¹ at 18 h, and 1089 ± 649 ng ml⁻¹ at 24 h for the 8 mg kg⁻¹ and 17 mg kg⁻¹ 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 7 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.
(Copyright © 2010 John Wiley & Sons, Ltd.)