Abstract
Lolitrem B is the most potent indole-diterpene mycotoxin produced by Epichloë festucae var. lolii (termed LpTG-1), with severe intoxication cases reported in livestock. To date, there are no in vivo metabolism studies conducted for the mycotoxin. A mouse model assay established for assessing toxicity of indole-diterpenes was used to investigate metabolic products of lolitrem B. Mice were administered lolitrem B at 0.5 and 2.0 mg/kg body weight (b.wt) intraperitoneally before body and brain tissues were collected at 6 h and 24 h post-treatment. Samples were cryoground and subjected to a biphasic or monophasic extraction. The aqueous and lipophilic phases were analysed using liquid chromatography high-resolution mass spectrometry (LC–HRMS); data analysis was performed with Compound Discoverer™ software. A total of 10 novel phase I metabolic products were identified in the lipophilic phase and their distribution in the liver, kidney and various brain regions are described. The biotransformation products of lolitrem B were found to be present in low levels in the brain. Based on structure–activity postulations, six of these may contribute towards the protracted tremors exhibited by lolitrem B-exposed animals.
Highlights
Many mycotoxins are contaminants of agricultural products found in animal feed and human food [1,2,3,4,5,6]
The mycotoxin lolitrem B (Figure 1) is the major compound responsible for ryegrass staggers and the most abundant indole-diterpene produced by perennial ryegrass endophyte
The neurological signs associated with perennial ryegrass toxicosis (PRGT) has been reported in Australia, New Zealand, Pacific northwest of USA and Europe [7]
Summary
Many mycotoxins are contaminants of agricultural products found in animal feed and human food [1,2,3,4,5,6]. 25, 372B at 1800–2000 parts per billion (ppb) as the maximum allowable limit in imported levels of2020, lolitrem feed (straw) [10,11] This threshold was established from field-based behavioural observations, where levels above 1800 were implicated in naturally occurring outbreakswhere of perennial ryegrass. The identification and distribution of the lolitrem B metabolic products in the liver, kidney and various brain regions were determined and found to be present in these tissues Six of these compounds are thought to be tremorgenic based on hypotheses related to structure–activity postulations [26] and are very likely to be present in animal products for human consumption. It is important to establish the risks associated with exposure of these compounds to humans as well as grazing livestock
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