Graham Centre for Agricultural Innovation (Charles Sturt University and NSW Department of Primary Industries), Wagga Wagga, NSW, 2650, Australia; Charles Sturt University, School of Agricultural and Wine Sciences, Wagga Wagga, NSW, 2678, Australia.
Graham Centre for Agricultural Innovation (Charles Sturt University and NSW Department of Primary Industries), Wagga Wagga, NSW, 2650, Australia.
Phytochemistry. 2019 May;161:1-10. doi: 10.1016/j.phytochem.2019.01.016. Epub 2019 Feb 15.
Amaranthus retroflexus L., an introduced invasive weed in southern Australia, has been associated with acute renal failure and/or mortality in a number of livestock species. While its leaves, flowers and stems are generally reported to contain high levels of nitrogen, few studies have fully characterised the chemical composition of A. retroflexus foliage with respect to mammalian toxicity. We performed extensive metabolic profiling of stems, leaves, roots and inflorescence tissues of A. retroflexus collected from three spatially and/or temporally distinct toxicity outbreaks, and report on the 1) composition of primary and secondary metabolites in methanolic extracts of A. retroflexus tissues using HPLC and HPLC-MS QToF and 2) chemometric analysis of A. retroflexus extracts in relation to the associated toxin(s). All tissues of A. retroflexus possessed an abundance of N-containing metabolites, particularly quaternary ammonium compounds which were identified as betaines, two of which (valine betaine and isoleucine betaine) are rarely encountered in plants. Cytotoxicity to murine fibroblasts was highest in extracts of leaf tissue and was associated with a single, a small modified peptide with high similarity to N-acetyl-L-α-aspartyl-L-alanyl-L-α-aspartyl-L-α-glutamyl-O-(carboxymethyl)-L-tyrosyl-L-leucinamide, a synthetic phosphotyrosyl mimic involved in cell signaling processes. One possible mode of action leading to acute renal failure in grazing livestock by a modified peptide such as this is proposed.
反枝苋（Amaranthus retroflexus L.）是澳大利亚南部一种入侵性杂草，与多种家畜物种的急性肾功能衰竭和/或死亡有关。虽然其叶子、花和茎通常被报道含有高水平的氮，但很少有研究充分描述了反枝苋叶子的化学成分与哺乳动物毒性之间的关系。我们对从三个空间和/或时间上不同的毒性爆发中采集的反枝苋的茎、叶、根和花序组织进行了广泛的代谢物分析，并报告了 1）使用 HPLC 和 HPLC-MS QToF 分析反枝苋组织甲醇提取物中的初级和次级代谢物的组成，以及 2）根据相关毒素对反枝苋提取物进行化学计量分析。反枝苋的所有组织都含有丰富的含氮代谢物，特别是季铵化合物，这些化合物被鉴定为甜菜碱，其中两种（缬氨酸甜菜碱和异亮氨酸甜菜碱）在植物中很少见。叶组织提取物对鼠成纤维细胞的细胞毒性最高，与一种单一的、小的修饰肽有关，该肽与 N-乙酰-L-α-天冬酰基-L-丙氨酸-L-α-天冬酰基-L-α-谷氨酸-O-（羧甲基）-L-酪氨酸-L-亮氨酰胺具有高度相似性，这是一种参与细胞信号转导过程的合成磷酸酪氨酸类似物。提出了一种可能的作用模式，即通过这种修饰肽导致放牧家畜发生急性肾功能衰竭。
