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United States Department of Agriculture

Agricultural Research Service

Research Project: THE TOXICITY OF PYRROLIZIDINE ALKALOID-CONTAINING PLANTS AND OTHER HEPATOTOXIC AND NEUROTOXIC PLANTS

Location: Poisonous Plant Research

Title: Dehydropyrrolizidine alkaloids in two Cryptantha species: Including two new open chain diesters one of which is amphoteric

Authors
item Colegate, Steven
item Gardner, Dale
item Davis, Thomas
item Betz, Joseph -
item Panter, Kip

Submitted to: Phytochemical Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 13, 2012
Publication Date: January 2, 2013
Citation: Colegate, S.M., Gardner, D.R., Davis, T.Z., Betz, J.M., Panter, K.E. 2013. Dehydropyrrolizidine alkaloids in two Cryptantha species: Including two new open chain diesters one of which is amphoteric. Phytochemical Analysis. 24: 201-12.

Interpretive Summary: Prompted by a livestock poisoning outbreak near Kingman, Arizona, analysis of Cryptantha inequata and C. utahensis revealed dehydropyrrolizidine alkaloids at approximately 0.05 % and 0.09% w/w respectively. Cryptantha inequata produced mainly echimidine, acetylechimidine and echiuplatine; dehydropyrrolizidine alkaloids previously associated with Echium plantagineum. Echiuplatine was elucidated as an amphoteric, open chain diester with angelic acid and 3-hydroxy-3-methylglutaric acid. Along with lycopsamine, intermedine and dihydroxyechiumine, C. utahensis produced cryptanthine, an open chain diester with angelic acid and 2,3-dihydroxy-2-methylbutanoic acid. All pyrrolizidine alkaloids detected were present in the plants mainly as their N-oxides. The dehydropyrrolizidine alkaloids detected are expected to be toxic but the low levels in the plants potentially mitigate the risk. The identification of the amphoteric echiuplatine provides a cautionary note with respect to the analysis of total dehydropyrrolizidine alkaloid content.

Technical Abstract: A livestock poisoning outbreak near Kingman, Arizona, USA, potentially linked to dehydropyrrolizidine alkaloids, prompted an evaluation of some local plants for the presence of these hepatotoxic alkaloids. Two species of Cryptantha, a Boraginaceous genus previously shown to produce potentially toxic pyrrolizidine alkaloids, were collected from the vicinity of Kingman, Arizona. Plant extracts were analysed using HPLC–electrospray ionisation (+)–MS and MS/MS to determine the presence of dehydropyrrolizidine alkaloid esters. Identities were confirmed by comparison of chromatographic and MS data with authenticated standards and, in the case of the previously undescribed alkaloids, using one- and two-dimensional NMR spectroscopy and high-resolution mass measurement. Cryptantha inequata and C. utahensis were shown to produce retronecine-based dehydropyrrolizidine alkaloids at approximately 0.05% and 0.09% w/w respectively. Cryptantha inequata produced mainly echimidine, acetylechimidine and echiuplatine; dehydropyrrolizidine alkaloids that were previously associated with Echium plantagineum. The previously undescribed structure of echiuplatine was elucidated as an amphoteric, open chain diester with angelic acid and 3-hydroxy-3-methylglutaric acid. Along with lycopsamine, intermedine and dihydroxyechiumine, C. utahensis produced cryptanthine, a previously undescribed open chain diester alkaloid esterified with angelic acid and 2,3-dihydroxy-2- methylbutanoic acid. All pyrrolizidine alkaloids detected were present in the plants mainly as their N-oxides. The retronecine-based alkaloids detected in both Cryptantha species herein investigated aligns them within the Krynitzkia subgenus. The dehydropyrrolizidine alkaloids detected are expected to be toxic but the lowlevels in the plants potentially mitigate the risk. The identification of the amphoteric echiuplatine provides a cautionary note with respect to the analysis of total dehydropyrrolizidine alkaloid content.

Last Modified: 4/18/2014
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