The female flowers of the hop plant have long been used as a preservative and a flavoring agent in beer, but they are now being included in some herbal preparations for women for "breast enhancement."
METHODS AND RESULTS:
This study investigated the relative estrogenic, androgenic and progestogenic activities of the known phytoestrogen, 8-prenylnaringenin, and structurally related hop flavonoids. 6-Prenylnaringenin, 6,8-diprenylnaringenin and 8-geranylnaringenin exhibited some estrogenicity, but their potency was less than 1% of that of 8-prenylnaringenin. 8-Prenylnaringenin alone competed strongly with 17ss-estradiol for binding to both the alpha- and ss-estrogen receptors. None of the compounds (xanthohumol, isoxanthohumol, 8-prenyl-naringenin, 6-prenylnaringenin, 3'-geranylchalconaringenin, 6-Geranylnaringenin, 8-geranylnaringenin, 4'-O:-methyl-3'-prenylchalconaringenin and 6,8-diprenylnaringenin) nor polyphenolic hop extracts showed progestogenic or androgenic bioactivity.
CONCLUSIONS:
These results indicate that the endocrine properties of hops and hop products are due to the very high estrogenic activity of 8-prenylnaringenin and concern must be expressed about the unrestricted use of hops in herbal preparations for women. |