Phytoestrogen from Pinus ponderosa assayed by competitive binding with 17beta-estradiol to mouse uterine cytosol.
Ponderosa pine needle extracts contained a phytoestrogen that competed with 17beta-estradiol for specific binding to mouse uterine cytosol. Phytoestrogen was separated from the initial aqueous extract by acetone fractionation and eluted from a polyvinylpyrrolidone column with 90% methanol. Forty microg/ml was determined as the concentration of most purified phytoestrogen displacing 50% of 17beta-estradiol (15 pg/ml) from the estrogen specific binding sites of the mouse uterine cytosol. Intraperitoneal administration of 200 microg (0.3 g needle equivalents) of the phytoestrogen was equal in activity to 10 ng of 17beta-estradiol in a 24 hour uterine growth assay in immature mice. The phytoestrogen was retained in dialysis tubing with a 14,000 molecular weight cutoff and displayed an ultraviolet absorbance maximum at 208 nm, void of any phenolic chromophores. Phytoestrogen was being evaluated as a contributory factor in Ponderosa pine needle-induced abortion observed in range cattle.
Wagner
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Biochemistry Group, Chemistry Department, Montana State University, Bozeman, Montana 59717, USA.
Jackson
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