Poisonous Properties of Larkspur (Delphinium spp.)

Abstract

Some members of the tribe DelphineaeWarming are useful as forage for grazing cattle or as a source of medicaments for man. However, under certain circumstances their consumption results in poisoning, apparently because of norditerpenoid alkaloids. At least 150 diterpenoid alkaloids have been identified in Delphinium. In this report, factors influencing the alkaloid content and the toxicity of the plant are discussed. Relative change in content of eight alkaloids at four stages of growth of Delphinium occidentale (Watson) Watson is reported . The most dominant alkaloids in nine species of Delphinium are listed. Toxicity of eight species was compared al the flower stage of growth using a mouse assay with D. barbeyi; (Huth) Huth being about four times more toxic than D. glaucescens Rydb. or D. geyeri Greene and about ten times more toxic than Consolida CV., D. accidentale, or Aconitum columbianum var. columbianum Nutt. (vegetative stage). Stress by aphid infestation or relatively low water availability had little if any effect on toxicity of D. barbeyi and D. occidentale, respectively. From chemical analysis of D. barbeyi tested previously in cattle. the LD₅₀ for a s ingle intraruminal dose of methyllycaconitine was estimated to be less than 6.3 mg/kg body wt.