A Screen for Swainsonine in Select North American Astragalus Species

Abstract

Swainsonine is found in several plant species worldwide, and causes severe toxicosis in livestock grazing these plants, leading to a chronic condition characterized by weight loss, altered behavior, depression, decreased libido, infertility, and death. Swainsonine has been detected in 13 North American Astragalus species of which eight belong to taxa in four taxonomic sections, the Densifolii, Diphysi, Inflati, and Trichopodi. These sections belong to two larger groups representing several morphologically related species, the Pacific Piptolobi and the small-flowered Piptolobi. The objective of this study was to screen the other 31 species for swainsonine in sections Densifolii, Diphysi, Inflati, and Trichopodi previously not known to contain swainsonine. Furthermore, to broaden the scope further, 21 species within the 8 sections of the Pacific Piptolobi and the small flowered Piptolobi were screened for swainsonine. Swainsonine was detected for the first time in 36 Astragalus taxa representing 29 species using liquid and gas chromatography coupled with mass spectrometry. Several taxonomic sections were highly enriched in species that contain swainsonine while others were not. A systematic examination for swainsonine in these species will provide important information on the toxic risk of these species and may be a valuable reference for diagnosticians and land managers.

Characterization and Comparative Analysis of Complete Chloroplast Genomes of Three Species From the Genus Astragalus (Leguminosae)

“…The structures and locations of the genes are shown in Figure 1. In comparison with other angiosperm plastid genomes, all three species lost rps16, rpl22, and infA, consistent with the A. membranaceus cp genome (Cook et al, 2017b). However, rps16 and rpl22 could be found in most angiosperm cp genomes (Shen et al, 2018;Biju et al, 2019;Liu et al, 2019).…”

Use of Herbarium Voucher Specimens To Investigate Phytochemical Composition in Poisonous Plant Research

“…Similar to the observation noted by Williams and Barneby in regard to the nitrotoxins, several taxonomic sections were over-represented in the species that contained swainsonine, suggesting a chemotaxonomic relationship among these species. For example, among the 29 species in the section Inflati that were evaluated, 25 species contained swainsonine . Similar observations were found for sections Trichopodi and Densifolii .…”

“…The problem with many of these anecdotal reports and/or use of non-specific methods was the lack of botanical vouchers for the material analyzed and/or used for experimental reproduction of the toxicosis. Using more specific methods of GC–MS and/or HPLC–MS, herbarium specimens were used to investigate Astragalus, Oxytropis, and Swainsona species for the indolizidine alkaloid swainsonine. − To facilitate this research, a simplified, single-step, small-scale extraction method using acetic acid was developed for the small mass of plant material sampled from the herbarium specimens …”

Phylogenetic Patterns of Swainsonine Presence in Morning Glories

“…One exception is a phylogenetic clade composed of six North American and eight South American Astragalus species ( Wojciechowski et al, 1999 ; Scherson et al, 2008 ). Surveys for S+ species of Astragalus identified swainsonine in 13 of these 14 species in this clade that share a common phylogenetic origin ( Cook et al, 2017b , c ). Among the more than 50 species of Astragalus that were reported to contain swainsonine in North and South America that includes the 13 mentioned above ( Cook et al, 2017b , c ), many share common morphological features, such as an inflated pod, as they co-occur in morphologically related taxonomic sections ( Barneby, 1964 ).…”

“…Lastly, two swainsonine-containing Sida species (Malvaceae) have been identified in South America due to poisoning of livestock ( Colodel et al, 2002 ; Micheloud et al, 2017 ). More recently, preserved herbarium specimens have been used to test and identify several Astragalus , Oxytropis , and Swainsona species that contain swainsonine ( Cook et al, 2016 , 2017b , c , d ). Herbarium specimens provide an excellent resource to investigate the phytochemical composition of plants and their distribution among species ( Cook et al, 2021 ).…”