Amaranthus retroflexus, originating from South America is an introduced weed in many parts of the world, including Australia. Ingestion of the plant material has been associated with acute renal failure in a number of livestock species including cattle, sheep and horse. While previous reports indicated that its foliage contains high levels of nitrogen, the characterization of the chemical composition of A. retroflexus foliage has not been performed fully, with differentiation of constituents in plant parts such as the leaf, stem, inflorescence and root. We report here the composition of the secondary metabolites of A. retroflexus foliage and the results of bioassay-guided cytotoxicity assessment of A. retroflexus extracts in an attempt to isolate and identify the associated toxins. As determined by UPLC-MS QTOF, all tissues (leaves, flowers, stems and roots) of A. retroflexus possessed an abundance of nitrogen-containing compounds, the primary constituents of which had apparent molecular formulae of C8H18NO2 and C9H20NO2, potentially the methyl and ethyl esters, respectively, of 4-oxo-1-butanaminium, a structural relative of choline. Cytotoxicity, as measured by MTT assay against the murine fibroblast cell line NIH3T3, was associated with a single compound in the extracts of A. retroflexus leaves, which we have tentatively identified as a compound with a high degree of similarity to the modified peptide N-acetyl-L-α-aspartyl-L-alanyl-L-α-aspartyl-L-α-glutamyl-O-(carboxymethyl)-L-tyrosyl-L-leucinamide, a mammalian metabolite known to play a role in cell signalling. Confirmation of the bioactivity of the putative toxin by comparisons with an authentic standard is required to ascertain nephrotoxic activity associated with livestock poisoning.
|Number of pages||1|
|Publication status||Published - 2018|
|Event||10th International Symposium on Poisonous Plants : ISOPP 10 - Red Lion Conference Center, St George , United States|
Duration: 16 Sep 2018 → 20 Sep 2018
|Conference||10th International Symposium on Poisonous Plants|
|Period||16/09/18 → 20/09/18|
Weston, P., Gurusinghe, S., Birckhead, E., Skoneczny, D., Weston, L., & Quinn, J. (2018). Characterisation and bioactivity of secondary metabolites of Amaranthus retroflexus L. implicated in livestock poisoning. 53. Poster session presented at 10th International Symposium on Poisonous Plants , St George , United States.