Preparation of tetrahydroagathic acid: a serum metabolite of isocupressic acid, a cattle abortifacient in ponderosa pine

Spontaneous abortion in cattle after consumption of Hesperocyparis (Cupressus) macrocarpa (Hartw.) Bartel and Cupressus arizonica (Greene) needles in Uruguay

An outbreak of cattle abortion associated with the consumption of Hesperocyparis (Cupressus) macrocarpa and Cupressus arizonica needles has been reported in Uruguay. Twenty-five of 125 pregnant heifers in late-term pregnancy aborted after being introduced into a paddock containing numerous H. macrocarpa, C. arizonica and Casuarina cunninghamiana trees. There were no significant macroscopic or histological findings in the two fetuses analyzed. Abortifacient labdane acids were detected in the needles of H. macrocarpa (1.68%, D.W.) and C. arizonica (0.36%, D.W.) but none were found in C. cunninghamiana.

Development of enzyme-linked immunosorbent assays for isocupressic acid and serum metabolites of isocupressic acid

The consumption of ponderosa pine (Pinus ponderosa), lodgepole pine (Pinus contorta), common juniper (Juniperus communis), and Monterey cypress (Cupressus macrocarpa) causes abortions in pregnant cattle. Recent studies have identified isocupressic acid (1) as the primary abortificient compound in these plants. In vitro and in vivo studies using rumen and blood have shown isocupressic acid (1) is rapidly metabolized to agathic acid (3), dihydroagathic acid (4), and tetrahydroagathic acid (5). Rapid and sensitive diagnostic techniques are needed to identify poisoned animals, to study toxicokinetics, and to elucidate the mechanism of isocupressic acid-induced abortion in cattle. In this study, four competitive inhibition enzyme-linked immunosorbent assays for isocupressic acid and its sera metabolites were developed using polyclonal antibodies. One assay is specific to 1, whereas the other three assays show cross-reactivity to 3-5 in addition to 1. The assay specific to 1 had a limit of detection of 44.1 pg. The other assays which demonstrated cross-reactivity to the isocupressic acid blood metabolites also had comparably low limits of detection. One assay was used to follow the absorption and elimination profile of isocupressic acid metabolites in both cow serum and urine after oral dosage of a cow with common juniper.