Oestrogenic activity of the hop phyto-oestrogen, 8-prenylnaringenin.
Level 5 - mechanism / opinion, no new human data
Preclinical in vitro assays and animal (mouse) models
What was done
Researchers evaluated the estrogenic activity of natural and semi-synthetic 8-prenylnaringenin (a phytoestrogen from hops) and its (R)- and (S)-enantiomers. Testing included in vitro assays using a yeast screen transfected with human estrogen receptors, human Ishikawa Var-I cells, and binding assays to estrogen receptor isoforms ERalpha and ERbeta, comparing potency against coumestrol, genistein, and daidzein. In vivo effects were tested using an acute uterine vascular permeability assay and by administering the compound in drinking water to ovariectomized mice to assess vaginal epithelial stimulation.
What was found
Natural and semi-synthetic 8-prenylnaringenin, as well as both enantiomers, exhibited similar bioactivities and comparable binding affinity to both ERalpha and ERbeta. In vitro estrogenic activity of 8-prenylnaringenin was higher than that of coumestrol, genistein, and daidzein. In vivo, the compound increased uterine vascular permeability, but stimulation of the vaginal epithelium in ovariectomized mice required drinking water concentrations of 100 mug ml(-1), which is approximately 500-fold higher than concentrations present in beer.
Why it matters
This study establishes 8-prenylnaringenin as a potent hop-derived phytoestrogen that binds both ER isoforms, while showing that physiological effects via dietary intake like beer consumption require doses far higher than typical beverage levels.
Limits
The findings are limited entirely to in vitro cellular assays and rodent models. The abstract does not provide specific sample sizes (n) or exact binding affinities/potency metrics (e.g., Kd or EC50 values). Pharmacokinetics, human tissue bioavailability, and clinical outcomes were not evaluated.
Cited by
- context Beer and hops have direct pro-estrogenic effects.