Identification and Distribution of Novel Metabolites of Lolitrem B in Mice by High-Resolution Mass Spectrometry

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.

Epichloë Endophyte Infection Rates and Alkaloid Content in Commercially Available Grass Seed Mixtures in Europe

“…When recognized in a timely manner, the intoxication is reversible [25] and the intoxication risk of humans due to consumption of animal products such as milk is considered to be low, because concentrations of alkaloids in the milk of intoxicated cows are below the toxicity threshold [26]. L. perenne can also be infected with the allopolyploid Epichloë hybrida (LpTG-2) [27], and the haploid LpTG-3 (such as AR37) that is able to provide resistance against porina larvae (Wiseana cervinata) through production of epoxy-janthithrems, which also have tremorgenic effects but not as potent as lolitrem B [28][29][30][31]. Fescue toxicosis is caused by the ergot alkaloid ergovaline, produced predominantly by Epichloë coenophiala infecting tall fescue, but has also been observed in some Epichloë festucae var.…”

Toxicological Assessment of Pure Lolitrem B and Ryegrass Seed Infected with the AR37 Endophyte Using Mice

“…These findings are not surprising given these toxins are highly lipophilic [29]. Although no information is known about the metabolism of the epoxyjanthitrems, some work on lolitrem B has been published [30].…”