title: The effect of 7, 8-methylenedioxylycoctonine-type diterpenoid alkaloids on the toxicity of tall larkspur (Delphinium spp.) in cattle.
abstract: Delphinium spp. contain numerous norditerpenoid alkaloids which are structurally delineated as 7, 8-methylenedioxylycoctonine (MDL) and N-(methylsuccinimido) anthranoyllycoctonine (MSAL)-type alkaloids. The toxicity of many tall larkspur species has been primarily attributed to their increased concentration of MSAL-type alkaloids, such as methyllycaconitine (MLA), which are typically 20 times more toxic than MDL-type alkaloids. However, the less toxic MDL-type alkaloids are often more abundant than MSAL-type alkaloids in most Delphinium barbeyi and Delphinium occidentale populations. Previous research demonstrated that MDL-type alkaloids increase the acute toxicity of MSAL-type alkaloids. In this study, we examined the role of MDL-type alkaloids on the overall toxicity of tall larkspur plants to cattle while controlling for the exact dose of MSAL-type alkaloids. Cattle were dosed with plant material from 2 different populations of tall larkspur containing either almost exclusively MDL- or MSAL-type alkaloids. These 2 plant populations were combined to create mixtures with ratios of 0.3:1, 1:1, 5:1, and 10:1 MDL- to MSAL-type alkaloids. The dose that elicited similar clinical signs of poisoning in mice and cattle was determined for each mixture on the basis of the MSAL-type alkaloid content. As the ratio of MDL- to MSAL-type alkaloids increased, the amount of MSAL-type alkaloids required to elicit clinical signs decreased. These results indicate that the less toxic MDL-type alkaloids in tall larkspur exacerbate the toxicity of the MSAL-type alkaloids. Consequently, both the amount of MSAL-type alkaloids and the amount of total alkaloids should be fully characterized to determine more accurately the relative toxicity of tall larkspur plant material.
authors.affiliation: USDA-ARS Poisonous Plant Research Laboratory, Logan, UT 84341. Kevin.Welch@ars.usda.gov
authors.forename: K D
authors.initials: KD
authors.lastname: Welch
authors.forename: B T
authors.initials: BT
authors.lastname: Green
authors.forename: D R
authors.initials: DR
authors.lastname: Gardner
authors.forename: D
authors.initials: D
authors.lastname: Cook
authors.forename: J A
authors.initials: JA
authors.lastname: Pfister
authors.forename: K E
authors.initials: KE
authors.lastname: Panter
mesh_terms: D000470:Alkaloids / Q000737:chemistry / Q000633:toxicity*; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000139:chemically induced*; D031882:Delphinium / Q000737:chemistry*; D004224:Diterpenes / Q000737:chemistry / Q000633:toxicity*; D007928:Lethal Dose 50; D008297:Male; D051379:Mice; D015394:Molecular Structure; D010939:Plant Poisoning / Q000662:veterinary; D010947:Plants, Toxic / Q000737:chemistry
chemical_list: C576842:7,8-methylenedioxylycoctonine; D000470:Alkaloids; D004224:Diterpenes