Evaluation of the Estrogenic Activity of the Wild Pueraria mirifica by Vaginal Cornification Assay

Abstract

Abstract. The aim of this study was to evaluate the estrogenic activity of tuberous samples of phytoestrogen-rich Pueraria mirifica collected from 25 of 76 provinces in Thailand by vaginal cornification assay. Tuberous powders were prepared and administered to ovariectomized rats for 14 consecutive days at dosages of 10, 100 and 1,000 mg/kg BW respectively, and were compared with a daily treatment with 2 mg/kg BW 17β-estradiol (E2). Rats treated with 10 mg/kg BW Pueraria mirifica showed no vaginal cornification. Treatment with 100 mg/kg BW Pueraria mirifica from 13 out of 25 plant samples resulted in development of vaginal cornification. The cell count percentages of the vaginal smeared cells for the treatment with the 2 plant samples that exhibited the fastest vaginal cornification revealed large variation in their estrogenic activities. Treatment with 1,000 mg/kg BW Pueraria mirifica from all plant samples produced vaginal cornification with the mean value for the period (day) of first appearance of cornified cells being 4.08 days compared to 2 days with 2 mg/kg BW E2. The overall appearance period (day) of cornified cells during the treatment and post-treatment period with 1,000 mg/kg BW per day Pueraria mirifica was shorter than treatment with 2 mg/kg BW E2. The results demonstrate that the plant population shows differential estrogenic activity as evaluated by vaginal cornification assay. , and isoflavones [5][6][7][8][9][10]. The estrogenic activity of miroestrol was first determined in ovariectomized rats. Administration of miroestrol produces a mammogenic effect in rats [11]. Using the vaginal cornification assay, miroestrol was estimated to have 0.25 times the estrogenic activity of 17β-estradiol [12]. Thus, various types of research have been conducted on the estrogenic effects of P. mirifica, especially in recent years. Crude P. mirifica powder can relief the climacteric symptoms of post-menopausal women [13]. The estrogenic activities of P. mirifica powder and extract has been evaluated in various species of experimental animals and found to have no toxicity [14]. P. mirifica has biphasic effects on MCF-7 cell proliferation, both suppression and stimulation [15], and an anti-proliferation effect on HeLa cells (ERα-negative human cervical adenocarcinoma cells) [16]. Considering the effects on the reproductive organs and reproductive-related hormones, P. mirifica suppresses luteinizing

Differential binding with ERα and ERβ of the phytoestrogen-rich plant Pueraria mirifica

“…A similar result was obtained in the previous evaluation of the estrogenic/antiestrogenic activity of a plant sample collected from Chiang Mai province when the plant extract was incubated with 17β-estradiol in a test with MCF-7 cells. The P. mirifica EtOH extract showed a significant antagonistic effect on 17β-estradiol at medium (100 µg/mL) and high (1000 µg/mL) doses (7). These two results demonstrate that antiestrogenic activity may be one of the key biological activities of P. mirifica extracts and might be related to its potential role in the prevention of breast cancer in rats (21).…”

“…The estrogenic and antiestrogenic activity of isoflavones, some of the major phytoestrogens, has been reported on the uterus of rats and mice (1,2), on mammalian cells (3), and yeast (4). There are various in vivo methods to measure the estrogenic activity of phytoestrogens, including an uterotropic assay (5) and vaginal cornification assay in ovariectomized rats (6)(7)(8). The MCF-7 screening test based on in vitro proliferation of the human mammary adenocarcinoma estrogen receptor (ER) α + cell line is able to demonstrate the biphasic (proliferative effect at low dose and antiproliferative effect at high dose) estrogenic response of phytoestrogen-rich plant extracts (9,10).…”

“…However, there is only one report about this plant that demonstrated the action of the plant phytoestrogens at the ERα and ERβ level (21). To help clarify the action of phytoestrogens from this plant on ERα and ERβ, a yeast estrogen screening (YES) test based on the yeast two-hybrid system was applied to the plant extracts of the same group of P. mirifica used in HPLC analysis of isoflavonoids (15) and in a vaginal cornification assay (6,7). This YES system was constructed by inserting the human estrogen receptor (hER) and coactivator into the yeast cells, which allowed specific binding of a ligand to the ER prior to interaction with the yeast transcription machinery.…”

The mutagenic and antimutagenic effects of the traditional phytoestrogen-rich herbs, Pueraria mirifica and Pueraria lobata

“…The plant tubers are rich in phytoestrogens, especially miroestrol (2), deoxymiroestrol (3), and isoflavonoids (1), and have been shown to be effective as an alternative treatment of menopausal symptoms (4). Consumption of the tuberous powder generates a strong estrogenic activity as revealed by the induction of vaginal cornification in ovariectomized rats (5,6) and by the MCF-7 cell proliferation assay (7). Treatment of gonadectomized rats with plant tuber powder resulted in a reduction of LH and FSH levels (8), with dose-dependent estrogenic responses in female mice (9), female monkeys (10), and menopausal monkeys (11)(12)(13).…”

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“…Recently, the phytoestrogen-rich plants, Pueraria spp. and related plants, have been the subject of interest for researchers, especially with respect to their estrogenic properties [2][3][4][5][6][7][8][9][10][11] . Pueraria spp.…”