title: Seasonal and Species Variation of the Hepatotoxin Indospicine in Australian Indigofera Legumes As Measured by UPLC-MS/MS.
abstract: Livestock industries have maintained a keen interest in pasture legumes because of the high protein content and nutritive value. Leguminous Indigofera plant species have been considered as having high feeding values to be utilized as pasture, but the occurrence of the toxic constituent indospicine in some species has restricted this utility. Indospicine has caused both primary and secondary hepatotoxicosis and also reproductive losses, but has only previously been determined in a small number of Indigofera species. This paper validates a high-throughput ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method to determine the indospicine content of various Indigofera species found in Australian pasture. Twelve species of Indigofera together with Indigastrum parviflorum plants were collected and analyzed. Of the 84 samples analyzed, *I. spicata (the asterisk indicates a naturalized species) contained the highest indospicine level (1003 ± 328 mg/kg DM, n = 4) followed by I. linnaei (755 ± 490 mg/kg DM, n = 51). Indospicine was not detected in 9 of the remaining 11 species and at only low levels (<10 mg/kg DM) in 2 of 8 I. colutea specimens and in 1 of 5 I. linifolia specimens. Indospicine concentrations were below quantitation levels for other Indigofera spp. (I. adesmiifolia, I. georgei, I. hirsuta, I. leucotricha, *I. oblongifolia, I. australis, and I. trita) and Indigastrum parviflorum. One of the more significant findings to emerge from this study is that the indospicine content of I. linnaei is highly variable (from 159 to 2128 mg/kg DM, n = 51) and differs across both regions and seasons. Its first regrowth after spring rain has a higher (p < 0.01) indospicine content than growth following more substantial summer rain. The species collected include the predominant Indigofera in Australia pasture, and of these, only *I. spicata and I. linnaei contain high enough levels of indospicine to pose a potential toxic threat to grazing herbivores.
authors: Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland , Health and Food Sciences Precinct, Coopers Plains, QLD 4108, Australia.|Food Technology Department, Faculty of Applied Sciences, Universiti Teknologi MARA , 40450 Shah Alam, Selangor, Malaysia.
authors: Eddie T T
authors: ET
authors: Tan
authors: Northern Territory Department of Primary Industry and Fisheries , Arid Zone Research Institute, Alice Springs, NT 0871, Australia.
authors: Christopher M
authors: CM
authors: Materne
authors: Queensland Department of Agriculture and Fisheries , Ecosciences Precinct, Dutton Park, QLD 4102, Australia.
authors: Richard G
authors: RG
authors: Silcock
authors: Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland , Health and Food Sciences Precinct, Coopers Plains, QLD 4108, Australia.|School of Agriculture and Food Sciences, Faculty of Science, The University of Queensland , Gatton, QLD 4343, Australia.
authors: Bruce R
authors: BR
authors: D'Arcy
authors: Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland , Health and Food Sciences Precinct, Coopers Plains, QLD 4108, Australia.
authors: Rafat
authors: R
authors: Al Jassim
authors: Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland , Health and Food Sciences Precinct, Coopers Plains, QLD 4108, Australia.
authors: Mary T
authors: MT
authors: Fletcher
mesh_terms: D001315:Australia; D002851:Chromatography, High Pressure Liquid; D029883:Indigofera / Q000737:chemistry* / Q000633:toxicity; D009646:Norleucine / Q000031:analogs & derivatives* / Q000032:analysis; D012621:Seasons; D053719:Tandem Mass Spectrometry; D014118:Toxins, Biological / Q000032:analysis*
chemical_list: D014118:Toxins, Biological; D009646:Norleucine; C058318:indospicine
keywords: Indigofera; indospicine; seasonal abundance; ultraperformance liquid chromatography−tandem mass spectrometry