Analysis of endophyte toxins: fescue and other grasses toxic to livestock

Abstract

Research on livestock toxicoses caused by Acremonium (endophyte)-infected grasses strongly implicate the ergopeptine alkaloids with A. coenophialum-infected fescue and paxilline and the lolitrem alkaloids with A. lolii-infected perennial ryegrass as the causative agents. Isolation, identification, and detection of these toxins involves extraction with appropriate solvents, clean-up procedures, and chromatographic methods with known standards. Thin-layer, high-performance liquid and gas chromatography along with ultraviolet and mass spectrometric (i.e., electron impact, chemical ionization, tandem mass) characterizations have been reported. These methods have varying degrees of success depending on the matrix from which the alkaloids have been extracted. Ergovaline is the primary ergopeptine alkaloid isolated from cultures of A. coenophialum and also from infected fescue grass and seeds toxic to livestock. Other compounds isolated from the endophyte-infected fescue include: lysergic acid amide (ergine), the clavine class of ergot alkaloids (chanoclavine I, agroclavine, elymoclavine, penniclavine), the pyrrolizidine alkaloids (N-formylloline, N-acetylloline, N-methyloline, N-acetylnorloline), and the unique pyrrolopyrazine alkaloid peramine. The loline alkaloids and peramine have been more associated with the insect-deterrent properties of the endophyte-infected fescue than with livestock toxicoses. Also, both peramine and the ergopeptine alkaloids (ergovaline, ergotamine) have been isolated from A. lolii-infected perennial ryegrass. More recently, paxilline and lolitrem B have been detected in laboratory cultures of A. coenophialum isolated from tall fescue. The ergot alkaloids in endophyte-infected perennial ryegrass may be more related to decreased animal productivity (weight gains, reproduction problems), whereas the lolitrems cause the staggers syndrome. The detection, isolation, identification, and analyses of these compounds from Acremonium-infected grasses is presented.

Effects of Endophyte Infection in Tall Fescue (Festuca arundinacea: Poaceae) on Community Diversity

“…A second point concerns the extent to which competitive superiority can be attributed to herbivory-deterring alkaloids in the grass. It is known that antipathogenic and antiherbivory properties are conferred by a diverse array of fungally derived alkaloids that become present in plant tissue (Bush et al 1993;Porter 1994). Many consider it to be logical that this relationship would evolve considering that within the plant kingdom, the Poaceae are one of only a few groups lacking the ability to produce secondary metabolites (such as alkaloids) on their own (Bacon and Hill 1996).…”

Genotypic and Chemotypic Diversity of Neotyphodium Endophytes in Tall Fescue from Greece

“…Collectively, these fungi are able to produce a range of bioactive alkaloids that deter herbivory, including the ergot alkaloids, pyrrolopyrazine (peramine), aminopyrrolizidines (lolines), and indole-diterpenes (including lolitrems and terpendoles) (7,47,53). Peramine and loline alkaloids confer anti-insect defenses to their host (7,51,57,63), while ergot alkaloids and lolitrem B cause fescue toxicosis and ryegrass staggers in grazing mammals, respectively (4,21,22,43).…”

A Simple Thin-Layer Chromatographic Method for the Detection of Ergovaline in Leaf Sheaths of Tall Fescue (Festuca Arundinacea) Infected with Neotyphodium Coenophialum

“…However, it has been recently claimed that a continuous exposure to ergovaline levels as low as 50 g/kg may be associated with subclinical alterations, 11 and thus some risk of economic losses could still exist in pastures where no ergovaline is detected by the present method.…”

“…Working-standard solutions containing 100 g/ml methanol were prepared weekly and stored at -5 C. To compare the concentration of primary solutions, a calibration curve was prepared with analytical-grade ergonovine using the colorimetric reaction 9 with p-dimethylamino benzaldehyde, c and the color was read with a UV/VIS spectrophotometer. d Tall fescue samples (about 200 g) were manually processed for separation of the leaf sheaths, which were finely ground in a mortar under liquid nitrogen (this procedure was adopted in order to facilitate the grinding of the fresh material while preserving ergovaline from thermal decomposition, 11 but other methods may be adequate, such as freeze drying 13 ). A weighed amount of the ground leaf sheaths (25 g) was extracted overnight with 100 ml methanol e in a 500-ml glass-stoppered conical flask.…”