Toxic Compounds from Poisonous Plants: Identification and Analytical Methods

A special issue of Toxins (ISSN 2072-6651). This special issue belongs to the section "Plant Toxins".

Deadline for manuscript submissions: closed (31 January 2024) | Viewed by 2857

Special Issue Editors


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Guest Editor
Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, Health and Food Sciences Precinct, Coopers Plains, QLD 4108, Australia
Interests: natural toxins; toxin characterization; phytotoxins; analytical methods; toxin degradation; food safety

E-Mail Website
Guest Editor
Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, Health and Food Sciences Precinct, Coopers Plains, QLD 4108, Australia
Interests: natural toxins; toxin characterization; phytotoxins; analytical methods; toxin degradation; food safety
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Special Issue Information

Dear Colleagues,

Plant toxins are secondary metabolites produced by a range of plant species that can have deleterious impacts on both human and animal health, and potentially form residues in food and feed commodities. Such toxins can be considered plant defenses against predation, and occur as widely varying chemical structures from simple amino acids such as indospicine to diverse pyrrolizidine alkaloids and beyond. Plant toxins have been identified as contaminants in herbal medicines and in cases of unintentional plant substitutions. In rare instances, plant toxins such as indospicine can accumulate in the tissues of grazing livestock and cause the secondary poisoning (and even death) of other animals. Plant toxins such as pyrrolizidine alkaloids have also been reported in honey where bees imbibe nectar from plants producing such alkaloids. Unlike mycotoxins, plant toxins are rarely regulated in food/feed, but diagnosis of their impact and/or prevalence requires the establishment of high-throughput analytical chemistry methods, such as LC-MS and GC-MS, with increasingly lower limits of detection. Thus, this Special Issue focuses on the identification and analysis of plant toxins, including in both plant and animal tissues, as well as implications for human and animal health.

Dr. Natasha Hungerford
Prof. Mary Fletcher
Guest Editors

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Keywords

  • plant toxins
  • natural toxins
  • analysis
  • mitigation
  • decontamination
  • human health
  • animal health

Published Papers (2 papers)

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Research

20 pages, 3448 KiB  
Article
Analysis of Pyrrolizidine Alkaloids in Stingless Bee Honey and Identification of a Botanical Source as Ageratum conyzoides
by Natasha L. Hungerford, Norhasnida Zawawi, Tianqi (Evonne) Zhu, Steve J. Carter, Kevin J. Melksham and Mary T. Fletcher
Toxins 2024, 16(1), 40; https://doi.org/10.3390/toxins16010040 - 12 Jan 2024
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Abstract
Stingless bee honeys (SBHs) from Australian and Malaysian species were analysed using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) for the presence of pyrrolizidine alkaloids (PAs) and the corresponding N-oxides (PANOs) due to the potential for such hepatotoxic alkaloids to contaminate honey [...] Read more.
Stingless bee honeys (SBHs) from Australian and Malaysian species were analysed using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) for the presence of pyrrolizidine alkaloids (PAs) and the corresponding N-oxides (PANOs) due to the potential for such hepatotoxic alkaloids to contaminate honey as a result of bees foraging on plants containing these alkaloids. Low levels of alkaloids were found in these SBHs when assessed against certified PA standards in targeted analysis. However, certain isomers were identified using untargeted analysis in a subset of honeys of Heterotrigona itama which resulted in the identification of a PA weed species (Ageratum conyzoides) near the hives. The evaluation of this weed provided a PA profile matching that of the SBH of H. itama produced nearby, and included supinine, supinine N-oxide (or isomers) and acetylated derivatives. These PAs lacking a hydroxyl group at C7 are thought to be less hepatoxic. However, high levels were also observed in SBH (and in A. conyzoides) of a potentially more toxic diester PA corresponding to an echimidine isomer. Intermedine, the C7 hydroxy equivalent of supinine, was also observed. Species differences in nectar collection were evident as the same alkaloids were not identified in SBH of G. thoracica from the same location. This study highlights that not all PAs and PANOs are identified using available standards in targeted analyses and confirms the need for producers of all types of honey to be aware of nearby potential PA sources, particularly weeds. Full article
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19 pages, 4401 KiB  
Article
Identification of Acid Hydrolysis Metabolites of the Pimelea Toxin Simplexin for Targeted UPLC-MS/MS Analysis
by Zhi Hung Loh, Natasha L. Hungerford, Diane Ouwerkerk, Athol V. Klieve and Mary T. Fletcher
Toxins 2023, 15(9), 551; https://doi.org/10.3390/toxins15090551 - 05 Sep 2023
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Abstract
Pimelea poisoning of cattle is a unique Australian toxic condition caused by the daphnane orthoester simplexin present in native Pimelea pasture plants. Rumen microorganisms have been proposed to metabolise simplexin by enzymatic reactions, likely at the orthoester and epoxide moieties of simplexin, but [...] Read more.
Pimelea poisoning of cattle is a unique Australian toxic condition caused by the daphnane orthoester simplexin present in native Pimelea pasture plants. Rumen microorganisms have been proposed to metabolise simplexin by enzymatic reactions, likely at the orthoester and epoxide moieties of simplexin, but a metabolic pathway has not been confirmed. This study aimed to investigate this metabolic pathway through the analysis of putative simplexin metabolites. Purified simplexin was hydrolysed with aqueous hydrochloric acid and sulfuric acid to produce target metabolites for UPLC-MS/MS analysis of fermentation fluid samples, bacterial isolate samples, and other biological samples. UPLC-MS/MS analysis identified predicted hydrolysed products from both acid hydrolysis procedures with MS breakdown of these putative products sharing high-resolution accurate mass (HRAM) fragmentation ions with simplexin. However, targeted UPLC-MS/MS analysis of the biological samples failed to detect the H2SO4 degradation products, suggesting that the rumen microorganisms were unable to produce similar simplexin degradation products at detectable levels, or that metabolites, once formed, were further metabolised. Overall, in vitro acid hydrolysis was able to hydrolyse simplexin at the orthoester and epoxide functionalities, but targeted UPLC-MS/MS analysis of biological samples did not detect any of the identified simplexin hydrolysis products. Full article
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