RESUMO
Isocoma pluriflora and Isocoma acradenia are toxic plants that contain the putative toxin tremetone. It is common for I. pluriflora to poison livestock in the southwestern United States. I. acradenia has been suspected of poisoning livestock but its toxicity has not been confirmed by association with clinical poisonings or experimental studies. Jersey calves dosed with I. pluriflora and I. acradenia for nine days developed "trembles" characterized by skeletal muscle degeneration and necrosis and large increases in serum creatine kinase activity. This is the first report of I. acradenia toxicity in an animal model. This study also demonstrates that I. pluriflora remains toxic even though tremetone concentrations in the plant were low due to storage of the plant for over five years. Thus, supporting recent research which indicates that another toxin in the plant may be responsible for, or at least contributes to causing "trembles" in livestock.
RESUMO
Isocoma pluriflora, a plant prevalent on land used for livestock production and native to Arizona, New Mexico, West Texas, and Northern Mexico, is poisonous and causes trembles in livestock. Tremetone and dehydrotremetone have been suggested as the toxic compounds in I. pluriflora. In this study several different Isocoma spp., including I. pluriflora, I. tenuisecta, I. azteca, I. acradenia, and I. rusbyi, that are native to land used for grazing livestock in the southwestern United States were analyzed by high performance liquid chromatography (HPLC) for tremetone, dehydrotremetone, and other structurally related compounds. This is the first report of tremetone, dehydrotremetone, and 3-oxyangeloyltremetone in I. tenuisecta, I. azteca, I. acradenia, I. rusbyi, and several other Isocoma spp. In addition, this is the first report of 4-hydroxy-3-(3-methyl-2-butenyl)acetophenone and 7-isopentenyloxycoumarin in Isocoma spp.