Investigation of the metabolism of ergot alkaloids in cell culture by fourier transformation mass spectrometry

Do Epichloë Endophytes and Their Grass Symbiosis Only Produce Toxic Alkaloids to Insects and Livestock?

Epichloë endophytes in forage grasses have attracted widespread attention and interest of chemistry researchers as a result of the various unique chemical structures and interesting biological activities of their secondary metabolites. This review describes the diversity of unique chemical structures of taxa from Epichloë endophytes and grass infected with Epichloë endophytes and demonstrates their reported biological activities. Until now, nearly 160 secondary metabolites (alkaloids, peptides, indole derivatives, pyrimidines, sesquiterpenoids, flavonoids, phenol and phenolic acid derivatives, aliphatic metabolites, sterols, amines and amides, and others) have been reported from Epichloë endophytes and grass infected with Epichloë endophytes. Among these, non-alkaloids account for half of the population of total metabolites, indicating that they also play an important role in Epichloë endophytes and grass infected with Epichloë endophytes. Also, a diverse array of secondary metabolites isolated from Epichloë endophytes and symbionts is a rich source for developing new pesticides and drugs. Bioassays disclose that, in addition to toxic alkaloids, the other metabolites isolated from Epichloë endophytes and symbionts have notable biological activities, such as antifungal, anti-insect, and phytotoxic activities. Accordingly, the biological functions of non-alkaloids should not be neglected in the future investigation of Epichloë endophytes and symbionts.

Comparative study on the metabolism of the ergot alkaloids ergocristine, ergocryptine, ergotamine, and ergovaline in equine and human S9 fractions and equine liver preparations

1. Ergopeptine alkaloids like ergovaline and ergotamine are suspected to be associated with fescue toxicosis and ergotism in horses. Information on the metabolism of ergot alkaloids is scarce, especially in horses, but needed for toxicological analysis of these drugs in urine/feces of affected horses. The aim of this study was to investigate the metabolism of ergovaline, ergotamine, ergocristine, and ergocryptine in horses and comparison to humans. 2. Supernatants of alkaloid incubations with equine and human liver S9 fractions were analyzed by reversed-phase liquid-chromatography coupled to high-resolution tandem mass spectrometry with full scan and MS² acquisition. Metabolite structures were postulated based on their MS² spectra in comparison to those of the parent alkaloids. All compounds were extensively metabolized yielding nor-, N-oxide, hydroxy and dihydro-diole metabolites with largely overlapping patterns in equine and human liver S9 fractions. However, some metabolic steps e.g. the formation of 8'-hydroxy metabolites were unique for human metabolism, while formation of the 13/14-hydroxy and 13,14-dihydro-diol metabolites were unique for equine metabolism. Incubations with equine whole liver preparations yielded less metabolites than the S9 fractions. 3. The acquired data can be used to develop metabolite-based screenings for these alkaloids, which will likely extend their detection windows in urine/feces from affected horses.

Co-exposure of the Mycotoxins Lolitrem B and Ergovaline in Steers Fed Perennial Ryegrass ( Lolium perenne) Straw: Metabolic Characterization of Excreta

Past research showed a strong linear correlation between levels of the mycotoxins lolitrem B (LB, a tremorgen) and ergovaline (EV, an ergot alkaloid and potent vasoconstrictor) in perennial ryegrass (PRG) forage. The purpose of this study was to characterize the excretion of these two compounds in beef cattle consuming PRG straw and to utilize liquid chromatography-tandem mass spectrometry to investigate the metabolism of LB and EV in excreta. Four groups of steers ( n = 6/group) were fed endophyte-infected PRG for 64 days (2256/638, 1554/373, 1012/259, or 247/<100 μg/kg LB/EV). Concentrations of LB and EV in both PRG straw and feces showed a linear relationship to each other. Feces reflected a dose-response for both mycotoxins, with values increasing most rapidly through 21 days then plateauing. Urine contained no detectable level of either compound or the ergoline lysergic acid. Screening for metabolites showed oxidation and reduction biotransformations for both toxins, with additional conjugation products detected for ergovaline.

Metabolomics of fescue toxicosis in grazing beef steers

Fescue toxicosis (FT) results from consumption of tall fescue (Lolium arundinaceum) infected with an endophyte (Epichloë coenophiala) that produces ergot alkaloids (EA), which are considered key etiological agents of FT. Decreased weight gains, hormonal imbalance, circulating cholesterol disruption, and decreased volatile fatty acid absorption suggest toxic (E+) fescue-induced metabolic perturbations. Employing untargeted high-resolution metabolomics (HRM) to analyze E+ grazing-induced plasma and urine metabolome changes, fescue-naïve Angus steers were placed on E+ or non-toxic (Max-Q) fescue pastures and plasma and urine were sampled before, 1, 2, 14, and 28 days after pasture assignment. Plasma and urine catecholamines and urinary EA concentrations were also measured. In E+ steers, urinary EA appeared early and peaked at 14 days. 13,090 urinary and 20,908 plasma HRM features were detected; the most significant effects were observed earlier (2 days) in the urine and later (≥14 days) in the plasma. Alongside EA metabolite detection, tryptophan and lipid metabolism disruption were among the main consequences of E+ consumption. The E+ grazing-associated metabolic pathways and signatures described herein may accelerate development of novel early FT detection and treatment strategies.

Ergot Alkaloids in Fattening Chickens (Broilers): Toxic Effects and Carry over Depending on Dietary Fat Proportion and Supplementation with Non-Starch-Polysaccharide (NSP) Hydrolyzing Enzymes

Ergot alkaloids (EA) are mycotoxins produced by Claviceps purpurea. EA-toxicity is poorly characterized for fattening chickens. Therefore, a dose-response study was performed to identify the lowest, and no observed adverse effect levels (LOAEL and NOAEL, respectively) based on several endpoints. Non-starch-polysaccharide (NSP) cleaving enzyme addition and dietary fat content were additionally considered as factors potentially influencing EA-toxicity. Feed intake was proven to respond most sensitively to the EA presence in the diets. This sensitivity appeared to be time-dependent. While LOAEL corresponded to a total dietary EA content of 5.7 mg/kg until Day 14 of age, it decreased to 2.03 mg/kg when birds were exposed for a period of 35 days. Consequently, NOAEL corresponded to an EA content of 2.49 mg/kg diet until Day 14 of age, while 1.94 mg/kg diet applied until Day 35 of age. Liver lesions indicating enzyme activities in serum were increased after 14 days of exposure. Dietary fat content and NSP-enzyme supplementation modified EA toxicity in an interactive manner. The EA residues in serum, bile, liver and breast meat were <5 ng/g suggesting a negligible carry over of intact EA.

BILL E. KUNKLE INTERDISCIPLINARY BEEF SYMPOSIUM: Physiologic effects of ergot alkaloids: What happens when excretion does not equal consumption?

Increased persistence of tall fescue () infested with an endophytic fungus, (formerly ), in forage-based agriculture has led to increased effort in understanding the negative effects caused by consumption of ergot alkaloids by animals consuming this forage. Ergot alkaloids have been shown to have an extremely short plasma half-life, but this does not necessarily equate to total clearance. Studies that measured consumption and excretion of alkaloids have demonstrated that in the case of ergovaline, less is excreted than is consumed. The fate of ergot alkaloids that leave circulation but are not excreted is not well understood. Consequently, these "alkaloid balance studies" have led to speculation that ergovaline might bioaccumulate in the animal. Unfortunately, few data indisputably support this outcome. Progress has been slowed by the fact that the fungus produces a multitude of different ergot alkaloids that can bind to a variety of different receptors. Binding studies have shown that ergot alkaloids have unusually slow receptor dissociation rates that have been described as irreversible and contribute to a persistent signaling effect. In vitro analyses have revealed a potential for accumulation of ergot alkaloids through repetitive exposures to low concentrations creating a "depot" of alkaloids available to interact with receptors. The specific high binding affinity of ergot alkaloids combined with the potential turnover of alkaloids bound nonspecifically could extend residual effects of these compounds. Interestingly, cattle exposed to ergot alkaloids in vivo have a consistently lower vascular response to agonists that target receptors known to bind ergot alkaloids. If these same receptors are blocked with an antagonist, contractile response to ergopeptine alkaloids is also reduced significantly (>60% reduction). This observation that alkaloid exposure interrupts normal function of a receptor can persist 5 to 6 wk after animals have been removed from an ergot alkaloid source (and prolactin levels have long since returned to normal). Thus, clearance of ergot alkaloids from cattle grazing pasture with ergot alkaloid-producing endophytes may occur in a similar gradual manner. Studies that improve the understanding of how cattle process ergot alkaloids will help answer the question of whether ergot alkaloids bioaccumulate.

Toxic effects, metabolism, and carry-over of ergot alkaloids in laying hens, with a special focus on changes of the alkaloid isomeric ratio in feed caused by hydrothermal treatment

Ergot alkaloids (EA) are mycotoxins formed by Claviceps purpurea. Due to the large variation in EA content, the mass proportion of ergot (hardened sclerotia) in animal diets is not suited to establish safe levels of EA. Therefore, the aim of the present study was to examine the dose-dependent effects of dietary EA on laying hens. Ergoty rye or ergot-free rye (control diet) was included in the diets either untreated or after hydrothermal treatment ("expansion"). The total EA levels in five different diets containing 0-3% of untreated or expanded rye were 0.1-14.56 mg/kg (untreated rye) and 0.08-13.03 mg/kg (expanded rye). The average EA reduction amounted to 11% due to expanding. The proportions of the sum of all -inine isomers however were consistently higher (19.5-48.4%) compared to the sum of their -ine isomer counterparts which decreased at the same time. Most of the laying performance and reproductive traits were significantly compromised during the test period between weeks 22 and 42 of age when the diet with the highest EA content was fed. Toxic effects were less pronounced due to expanding. Relative weights of liver, proventriculus, and gizzard as well as the aspartate aminotransferase activity, the antibody titers to Newcastle disease virus, albumin, and total bilirubin concentrations were all significantly increased in hens fed at the highest dietary ergot level whereby expanding additionally modified the albumin and total bilirubin responses. No carry-over of EA into egg yolk and albumen, blood, liver, and breast muscle was found, but bile contained quantifiable levels of ergometrine and ergometrinine. Biological recovery of ingested individual alkaloids with the excreta varied from 2 to 22% and was strongly positive linearly related to the octanol to water partition coefficient (logkOW). This suggests the lipophilicity of alkaloids as a factor influencing their metabolism and elimination. Based on the overall results of this study, a lowest observed adverse effect level (LOAEL) of 14.56 mg EA/kg for laying hen diets can be proposed, while the no observed adverse effect level (NOAEL) corresponds to a dietary EA level of 3.72 mg/kg. However, it must be stressed that these critical levels apply for the specific EA pattern tested in the present experiment, while batches of ergot containing a less typical alkaloid composition, or other expanding conditions, might contribute to variations in the LOAEL/NOAEL.

Multi-mycotoxin Analysis of Finished Grain and Nut Products Using Ultrahigh-Performance Liquid Chromatography and Positive Electrospray Ionization-Quadrupole Orbital Ion Trap High-Resolution Mass Spectrometry

Ultrahigh-performance liquid chromatography using positive electrospray ionization and quadrupole orbital ion trap high-resolution mass spectrometry was evaluated for analyzing mycotoxins in finished cereal and nut products. Optimizing the orbital ion trap mass analyzer in full-scan mode using mycotoxin-fortified matrix extracts gave mass accuracies, δM, of < ± 2.0 ppm at 70,000 full width at half maximum (FWHM) mass resolution (RFWHM). The limits of quantitation were matrix- and mycotoxin-dependent, ranging from 0.02 to 11.6 μg/kg. Mean recoveries and standard deviations for mycotoxins from acetonitrile/water extraction at their relevant fortification levels were 91 ± 10, 94 ± 10, 98 ± 12, 91 ± 13, 99 ± 15, and 93 ± 17% for corn, rice, wheat, almond, peanut, and pistachio, respectively. Nineteen mycotoxins with concentrations ranging from 0.3 (aflatoxin B1 in peanut and almond) to 1175 μg/kg (fumonisin B1 in corn flour) were found in 35 of the 70 commercial grain and nut samples surveyed. Mycotoxins could be identified at δM < ± 5 ppm by identifying the precursor and product ions in full-scan MS and data-dependent MS/MS modes. This method demonstrates a new analytical approach for monitoring mycotoxins in finished grain and nut products.

Ergot alkaloids in feed for Pekin ducks: toxic effects, metabolism and carry over into edible tissues

Hardened sclerotia (ergots) of Claviceps purpurea contaminate cereal grains and contain toxic ergot alkaloids (EA). Information on EA toxicity in ducks is scarce. Therefore, the aim of the growth experiment (Day 0–49, n = 54/group) was to titrate the lowest observed adverse effect level (LOAEL) for total ergot alkaloids (TEA). A control diet was prepared without ergots, and the diets designated Ergot 1 to 4 contained 1, 10, 15 and 20 g ergot per kg diet, respectively, corresponding to TEA contents of 0.0, 0.6, 7.0, 11.4 and 16.4 mg/kg. Sensitivity of ducks to EA was most pronounced at the beginning of the experiment when feed intake decreased significantly by 9%, 28%, 41% and 47% in groups Ergot 1 to 4, respectively, compared to the control group. The experiment was terminated after two weeks for ducks exposed to Ergot 3 and 4 due to significant growth retardation. Ergot alkaloid residues in edible tissues were lower than 5 ng/g. Bile was tested positive for ergonovine (=ergometrine = ergobasine) with a mean concentration of 40 ng/g. Overall, the LOAEL amounted to 0.6 mg TA/kg diet suggesting that ducks are not protected by current European Union legislation (1 g ergot/kg unground cereal grains).

Ergot alkaloids: From witchcraft till in silico analysis. Multi-receptor analysis of ergotamine metabolites

The term Ergot is referred to the sclerotium of ascomycetes - a protective kernel produced during resting stage of some fungi - which replaces seeds of susceptible cereals and plants intended for human and animal diet. It contains various composition of tryptophan-derived toxins defined ergot alkaloids. Since sclerotia can be harvested and milled together with cereals, they represent a source of food and feed contamination after breakage and spreading of mycotoxins into the various milling fractions. The effects of ergot alkaloids, including those adverse for human health, have been known since the Middle Ages. Nevertheless, as recently stated by the European Food Safety Authority, further information is needed on metabolism and target receptors-binding of common alkaloids in food. Unfortunately, the experimental investigation is challenging due to the high costs in terms of time and money. This study was thus aimed at assessing whether the in silico modeling can be an effective tool to investigate the interaction between multiple serotonin receptors and a wide set of ergotamine metabolites, including experimentally detected molecules and predicted derivatives. Validated models provided precious insights about the effects exerted by metabolic modifications on the receptor-ligand interaction. Such structural information may be useful to support the design of further experimental analysis.

Cytotoxicity and fluorescence visualization of ergot alkaloids in human cell lines

The ergot alkaloids as secondary metabolites from fungi of the genus Claviceps are the focus of many investigations because of their pharmacological and toxicological properties. The main effects of ergot alkaloids are referred to an interaction with several receptor systems in the human body. It is well-known that ergot alkaloids are able to isomerize with one isomer being biologically active and one being only weakly active, whereas the activity is restricted to receptor interactions. Latest investigations have proven that ergot alkaloids also show cytotoxic effects and induce apoptosis in human primary cells. These effects seem to correlate with accumulation properties. It was the aim of our current study to determine such effects in cancer cell lines, because ergot derivatives are also used in tumor therapy. Our results confirm the apoptotic effects in two cancer cell lines (HepG2 and HT-29) in a high range, and accumulation measurements show an interesting correlation between the alkaloid concentration in the cell lysate of the receptor-inactive isomers and cytotoxicity. In addition, the strong accumulative effects were first visualized by fluorescence microscopy by taking advantage of the natural fluorescence properties of ergot alkaloids.

Identification and apoptotic potential of T-2 toxin metabolites in human cells

The mycotoxin T-2 toxin, produced by various Fusarium species, is a widespread contaminant of grain and grain products. Knowledge about its toxicity and metabolism in the human body is crucial for any risk assessment as T-2 toxin can be detected in processed and unprocessed food samples. Cell culture studies using cells of human origin represent a potent model system to study the metabolic fate of T-2 toxin as well as the cytotoxicity in vitro. In this study the metabolism of T-2 toxin was analyzed in a cell line derived from human colon carcinoma cells (HT-29) and primary human renal proximal tubule epithelial cells (RPTEC) using high-performance liquid chromatography coupled with Fourier transformation mass spectrometry (HPLC-FTMS). Both cell types metabolized T-2 toxin to a variety of compounds. Furthermore, cell cycle analysis in RPTEC proved the apoptotic effect of T-2 toxin and its metabolites HT-2 toxin and neosolaniol in micromolar concentrations.