The Biogeographical Distribution of Duncecap Larkspur (Delphinium occidentale) Chemotypes and Their Potential Toxicity

Abstract

Larkspurs (Delphinium spp.) are poisonous plants found on rangelands in western North America. Larkspur's toxicity has been attributed to the norditerpenoid alkaloids, which are divided into two main structural groups: the highly toxic (N-methylsuccinimido) anthranoyllycoctonine type (MSAL type) and the less toxic 7,8-methylenedioxylycoctonine type (MDL type). Plants high in the MSAL-type alkaloids are thought to be the most toxic to cattle, and the concentrations of these alkaloids have been used as a predictor of plant toxicity. Duncecap larkspur, Delphinium occidentale, occurs throughout much of the Intermountain West and Northwestern United States. Specimens from field collections and herbaria deposits were evaluated taxonomically and chemically. Two distinct alkaloid profiles were identified: one that contains the MSAL-type alkaloids and one that contains little, if any, MSAL-type alkaloids. Thus, plants with these two alkaloid profiles should differ in their toxic potential. Each profile was unique in its geographical distribution. These findings have important implications in grazing management decisions on D. occidentale-infested rangelands, and they demonstrate that botanical classification alone is not a good indicator to determine the toxic risk of D. occidentale.

Bioactive Alkaloids from Plants Poisonous to Livestock in North America

“…Structure‐function studies of norditerpenoid alkaloids have shown that the aromatic ester functional group on MLA is a significant haptophore, and that the succinimide group imparts significant toxicity to the alkaloids ,. Current research interest in larkspur alkaloids includes the identification of new alkaloids, [24,25], species alkaloid composition, risk assessment, and the study of biological activities in rats and insects ,…”

Adverse Effects of Larkspur (Delphinium spp.) on Cattle

“…Additionally, another tall larkspur species, D. stachydeum only contains non MSAL-type alkaloids [18]. Likewise in D. occidentale there are two chemotypes, one that contains both MSAL and non MSAL-type alkaloids and one that does not contain MSAL-type alkaloids [19]. Each chemotype has a distinct geographic distribution shown in Figure 3.…”

“…Even in the absence of chromatography, a simple flow injection mass spectrometry method can be a valuable tool in assessing the alkaloid composition of larkspurs [42]. Such flow injection methods have been valuable in chemo-typing the various larkspurs based on alkaloid profiles, geographical location and species identifications [17][18][19]. With development of fully hyphenated methods, such as LC-MS/MS, the sensitivity and selectivity have become sufficient for detection of very low concentration of alkaloids (i.e., ng/mL) in such samples as sera or tissue (liver) for the purposes of defining toxicokinetics [22,45,46] or for diagnostic purposes in the analysis of contaminated feed supplies, tissues, rumen content or fluid samples of poisoned animals ( Figure 4).…”

“…However, recent investigations into the toxicity of D. stachydeum populations demonstrated that some populations could potentially have adverse effects in cattle even though they do not contain MSAL-type alkaloids [18]. Based upon the results of the last few years of research, it has become evident that the toxicity of tall larkspur populations is greatly dependent upon the alkaloid profile of each species and even specific populations within a species [16,18,19,22]. Consequently, it is impossible to provide a general statement as to how much larkspur a cow can eat without dying, as a lethal dose of larkspur is completely dependent upon the alkaloid profile of the plant and the genetic susceptibility of the animal.…”

Virtual Herbarium of Kerala forest Research Institute, Peechi, Kerala, India

“…The relevance of herbarium specimens for reconstructing phenological changes associated with climate warming is well established [17][18][19] . Herbarium specimens have also been used in the fields of chemical ecology 20,21 , pollination ecology 22,23 and insectplant interactions 24 . With the advent of molecular systematics, the protocols for DNA isolation from herbarium specimens have been standardized 25,26 , and DNA extraction protocols from herbarium specimens of vascular plants as old as 200 years have been achieved.…”