Characterization and toxicity of Amanita cokeri extract.

The nonprotein amino acids 2-amino-3-cyclopropylbutanoic acid and 2-amino-5-chloro-4-pentenoic acid were isolated from the mushroom Amanita cokeri. The cyclopropyl amino acid is toxic to the fungus Cercospora kikuchii, the arthropod Oncopeltus fasciatus (milk weed bug), and the bacteria Agrobacterium tumefaciens, Erwinia amylovora, and Xanthomonas campestris. Toxicity to bacteria was reversible by addition of isoleucine to the medium. No toxicity was observed for 2-amino-5-chloro-4-pentenoic acid.