title: Oral administration of Brazilian propolis exerts estrogenic effect in ovariectomized rats.
abstract: Propolis, a natural product derived from plants by honeybees, is a mixture of several hundred chemicals, including flavonoids, coumaric acids, and caffeic acids, some of which show estrogen-like activity. In this study, the estrogenic activity of crude ethanolic extract of Brazilian propolis was determined using several in vitro and in vivo assays. Propolis was found to bind to human estrogen receptors (ERs). Furthermore, propolis induced the expression of estrogen-responsive genes in ER-positive MCF-7 and Ishikawa cells. These in vitro assays suggest that propolis exerts estrogenic activity; therefore, in vivo experiments were conducted using ovariectomized rats. Oral administration of propolis (55 or 550 mg/kg/day for 3 days) significantly increased uterine wet weight and luminal epithelium thickness in comparison with the corresponding values in the corn oil-treated control group. Moreover, propolis induced ductal cell proliferation in the mammary glands. These effects were completely inhibited by full ER antagonist ICI 182,780, confirming that the effects of propolis are mediated by the ER. Our data show that oral intake of propolis induces estrogenic activity in ER-expressing organs in vivo and suggest that Brazilian propolis is a useful dietary source of phytoestrogens and a promising treatment for postmenopausal symptoms.
authors: Faculty of Pharmacy, Meijo University.
authors: Yoshinori
authors: Y
authors: Okamoto
authors: Takao
authors: T
authors: Tobe
authors: Koji
authors: K
authors: Ueda
authors: Tatsuyuki
authors: T
authors: Takada
authors: Nakao
authors: N
authors: Kojima
mesh_terms: D000284:Administration, Oral; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D065171:Estrogen Receptor Antagonists / Q000494:pharmacology; D005260:Female; D000077267:Fulvestrant; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D061986:MCF-7 Cells; D042361:Mammary Glands, Human / Q000166:cytology; D009929:Organ Size / Q000187:drug effects; D010052:Ovariectomy; D048789:Phytoestrogens; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage* / Q000494:pharmacology*; D011429:Propolis; D017207:Rats, Sprague-Dawley; D011960:Receptors, Estrogen / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000235:genetics; D014599:Uterus / Q000187:drug effects
chemical_list: D065171:Estrogen Receptor Antagonists; D048789:Phytoestrogens; D010936:Plant Extracts; D011960:Receptors, Estrogen; D000077267:Fulvestrant; D004958:Estradiol; D011429:Propolis