Steroid metabolites of Acremonium coenophialum, an endophyte of tall fescue

Three Acremonium coenophialum metabolites, ergosterol, ergosterol peroxide, and ergosta-4,6,8. (14);22-tetraen-3-one, were isolated from field-grown, fungus-infected. (toxic) tall fescue and mycelium grown in vitro. Mycelium contained 10 J.Lg of total steroljmg dry weight of tissue, with ergosterol comprising 40% of the total sterols. Mycelium contained EP only when grown in the light. EP was toxic to brine shrimp, two bacterial species, and chick embryos. Whether EP is involved in tall fescue toxicity is not known, but it was the only toxic compound found in chloroform-methanol extracts from both fungus-infected fescue and laboratory-grown mycelium and EP was not found in nontoxic tall fescue. Cattle grazed on Kentucky 31 tall fescue (Festuca arundinaceae Schreb.) during the summer often exhibit symptoms known collectively as "summer syndrome". These symptoms include reduced weight gain, rough hair coat, slightly elevated temperature, excessive salivation, rapid breathing, and excitability (Hoveland et al., 1983). Although summer syndrome was previously associated with hot weather, recent research has shown that poor weight gain occurs throughout the grazing season when cattle feed on tall fescue infected with an endophytic fungus (Hoveland et al., 1983). Bacon et al. (1977) isolated the endophytic fungus Epichloe typhina (Fr.) Tulasne from bent grass. The imperfect (Anamorphic) stage of this fungus is Acremonium typhinum Morgan-Jones and Gams. The endophytic fungus isolated from tall fescue in Alabama, Georgia, Kentucky, Texas, and New Zealand (Morgan-Jones and Gams, 1982; Latch et al., 1984; White and Cole, 1985, 1985b) has been classified as A. coenop­ hialum Morgan-Jones and Gams; a perfect (teleomorphic) state has never been reported on tall fescue. According to Morgan-Jones (personal communication), the endo­ phytic anamorphs from bent grass and tall fescue differ morphologically as well as in host specificity. In our view, the fungus endophyte of tall fescue is A. coenophialum Morgan-Jones and Gams and all other names are errone­ ous. It has often been suggested that alkaloids are a likely cause of fescue foot and perhaps other problems associated