title: In vitro metabolism of formononetin and biochanin A in bovine rumen fluid.
abstract: The phyto-estrogens formononetin (7-hydroxy-4'methoxyisoflavone) and biochanin A (5-7-dihydroxy-4'-methoxyisoflavone) were independently incubated in vitro at 39 degrees C in bovine rumen fluid from a fistulated steer receiving an alfalfa hay diet. Formononetin was incubated in studies 1 and 2, whereas biochanin A was incubated in study 3. The isoflavones were separated and quantified by high performance liquid chromatography. In study 1, formononetin concentration, 14.80 micrograms/ml at time 0, declined to 1.16 micrograms/ml by 12 h and to .76 micrograms/ml by 24 h. Daidzein (7,4-dihydroxyisoflavone), .18 micrograms/ml at time 0, peaked at 12.92 micrograms/ml at 6 h and decreased to 1.30 micrograms/ml by 24 h. Equol (7,4'-dihydroxyisoflavan), detected at 6 h, peaked at 16.94 micrograms/ml at 18 h and dropped to 12.64 micrograms/ml at 24 h. In incubation study 2, formononetin declined from 17.57 micrograms/ml at time 0 to 7.08 micrograms/ml by 6 h. Daidzein concentration was 1.75 micrograms/ml at time 0 and increased to 12.03 micrograms/ml by 6 h. Equol was detected at 3 h and increased to 2.32 micrograms/ml at 6 h. The half-lives were 4.3 for formononetin and 9.8 h for daidzein in this in vitro system. In study 3, biochanin A, 8.54 micrograms/ml at time 0, decreased to 0 micrograms/ml by 12 h in incubation 3, whereas genistein (5,7,4'-trihydroxyisoflavone), 3.17 micrograms/ml at 1 h, peaked at 7.35 micrograms/ml at 4 h and decreased to .32 micrograms/ml at 24 h. Equol was not detected in incubation study 3. The half-lives of biochanin A and genistein were 3.9 and 5.5 h, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Texas A&M University Agricultural Research, Overton 75684.
authors.forename: J M
authors.initials: JM
authors.lastname: Dickinson
authors.forename: G R
authors.initials: GR
authors.lastname: Smith
authors.forename: R D
authors.initials: RD
authors.lastname: Randel
authors.forename: I J
authors.initials: IJ
authors.lastname: Pemberton
mesh_terms: D000818:Animals; D002417:Cattle / Q000378:metabolism*; D005419:Flavonoids / Q000378:metabolism*; D019833:Genistein; D066298:In Vitro Techniques; D007529:Isoflavones / Q000378:metabolism*; D008297:Male; D012417:Rumen / Q000378:metabolism*
chemical_list: D005419:Flavonoids; D007529:Isoflavones; C007768:formononetin; D019833:Genistein; C004541:biochanin A