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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #86282
Title: IN VITRO OXIDATIONS OF ISOCUPRESSIC ACID BY COW RUMEN PREPARATIONS: FORMATION OF AGATHIC AND DIHYDROAGATHIC ACIDS

Author
item LIN, SHWU-JIUAN - UNIVERSITY OF IOWA
item Short, Robert
item FORD, STEPHEN - IOWA STATE UNIVERSITY
item Grings, Elaine
item ROSAZZA, JOHN - UNIVERSITY OF IOWA

Submitted to: Journal of Natural Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Cattle will sometimes eat needles from Ponderosa pine trees. If this occurs in late pregnancy, abortions are induced with subsequent losses of calves and even cows. The abortion is caused by a substance(s) in the pine needles that starts a cascade of events that starts with a profound vasoconstriction of the uterine arterial bed and ends with an induced parturition and retained placenta. This research documents a chemical alteration of a compound in the rumen that could be one of the causes of this problem. These findings help understand how pine needle abortion is caused.

Technical Abstract: Isocupressic acid [15-hydroxylabda-8(17),13E-dien-19-oic acid] (IA) has been identified as one compound from Pinus ponderosa (Ponderosa pine) that is responsible for pine needle abortion in cattle. In vitro measurements of vasoconstrictor activity utilizing the intact vascular bed of an isolated perfused bovine placetome demonstrated that isocupressic acid lacked vasoactivity. We investigated the possibility that IA was metabolically transformed into other metabolites by microflora of the cow rumen. Isocupressic acid was incubated under anaerobic conditions for 48 h in an in vitro ruminal fluid mixture and was transformed into two metabolites. These metabolites were identified by GC/MS as agathic acid (labda-8(17),13E-dien-15,19-dioic acid) (AA) and dihydroagathic acid (labda-8(17)-ene-15,19-dioic acid) (DHAA). Metabolite identities were confirmed by chemical conversions of IA and imbricataloic acid into AA and DHAA respectively. Structures of synthetic metabolites were confirmed by 1H- and 13C-NMR, specific rotation, GC/MS and high resolution mass spectrometry. Plasma obtained from cows that were fed Ponderosa pine needles contained racemic DHAA but no IA or AA. The results suggest that IA is metabolically transformed to AA and racemic DHAA in the rumen, then absorbed into the bloodstream of cattle.