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Keywords:

  • Fungal Endophytes;
  • Toxins;
  • Symbiosis;
  • Sedative;
  • New Mexico;
  • Grasses;
  • Grazing;
  • Horses

Abstract

Stipa robusta (= Stipa vaseyi) is a perennial grass found in certain areas of the southwestern United States. It is commonly known as sleepygrass, as horses that ingest this grass may become profoundly somnolent or stuporous for periods of time lasting up to several days. In an attempt to determine the active principle(s), fractionation of a methanolic extract of sleepygrass infected with an Acremonium endophyte has yielded lysergic acid amide (20 μg/g dry wt), isolysergic amide (8), 8-hydroxylysergic acid amide (0.3), ergonovine (7), chanoclavine-l (15), and N-formylloline (18). Related alkaloids have been found in many endophyte-infected grasses. The dominant alkaloid constituent in sleepygrass, lysergic acid amide, has not previously been identified in a grass in such high concentration. Lysergic acid amide is likely to be the basis for the extreme sedative effects on animals, given past pharmocological work on the compound from the ergot fungus Claviceps paspali. © 1992 Wiley-Liss, Inc.