The endocrine activities of 8-prenylnaringenin and related hop (Humulus lupulus L.) flavonoids.
Level 5 - mechanism / opinion, no new human data
In vitro bench study of receptor binding and bioactivity
PubMed 11134162 · doi:10.1210/jcem.85.12.7168
What was done
Researchers evaluated the estrogenic, androgenic, and progestogenic activities of the hop flavonoid 8-prenylnaringenin alongside structurally related flavonoids (such as 6-prenylnaringenin, 6,8-diprenylnaringenin, 8-geranylnaringenin, xanthohumol, and isoxanthohumol) and polyphenolic hop extracts using receptor binding and bioactivity assays.
What was found
6-Prenylnaringenin, 6,8-diprenylnaringenin, and 8-geranylnaringenin exhibited estrogenic activity at less than 1% of the potency of 8-prenylnaringenin. 8-Prenylnaringenin alone strongly competed with 17beta-estradiol for binding to both alpha- and beta-estrogen receptors. None of the tested compounds or hop extracts exhibited detectable androgenic or progestogenic bioactivity. The abstract provides no exact quantitative binding affinities (such as Ki or IC50 values).
Why it matters
It identifies 8-prenylnaringenin as the primary driver of estrogenic activity in hops, raising safety considerations regarding the unregulated inclusion of hop extracts in female herbal supplements.
Limits
The findings are derived entirely from in vitro assays, without in vivo pharmacokinetic, metabolic, or clinical outcome data. Specific quantitative potency metrics (such as binding affinities or concentrations) were not reported in the abstract.
Cited by
- supports Beer and hops have direct pro-estrogenic effects.