Weak Estrogenic Activity Research Articles

Estrogenic activity of a naringinase-treated extract of Sophora japonica cultivated in Egypt

The naringinase-treated methanol extract of Sophora japonica L. (Fabaceae) seeds showed potent estrogen agonist activity. Through bioassay-guided isolation of the main active constituents from the naringinase-treated methanol extract of S. japonica, the aglycones genistein and kaempferol were found to be the main phytoestrogens in the naringinase-treated extract. In addition, kaempferol was nearly equipotent to genistein as an estrogen agonist. Concerning the compounds isolated from the untreated methanol extract, sophoricoside showed weak estrogenic activity on ERβ only.

A novel estrogenic compound transformed from fenthion under UV-A irradiation

The photo-transformed products of fenthion well-known as one of the most photosensitive organophosphorus insecticides and their estrogenic activities were investigated using a yeast two-hybrid assay incorporating the human estrogen receptor α (hERα). We identified fenthion sulfoxide and 3-methyl-4-methylsulfinylphenol (MMS) as the major transformed products and 3-methyl-4-(methylthio)phenol (MMP) as the minor product under UV-A irradiation. Further, significant estrogenic activity was observed in the solution irradiated for 160 min; this activity was evaluated as 18 pM converted to 17β-estradiol (E 2) equivalent concentration. By using authentic standards, it was found that MMP possessed weak estrogenic activity; its activity was evaluated as 1.7 × 10 −6 times compared with that of E 2. However, it was also revealed that the activity due to MMP was only 13%. From high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR) spectroscopies, we newly identified a significant estrogenic compound transformed from fenthion, O, O-dimethyl S-[3-methyl-4-(methylthio)phenyl]phosphorothioate, S-aryl fenthion.

Further report on the endocrinological profile of two synthetic estrogens with antifertility properties, STS 456 and STS 593.

Two synthetic estrogens, STS 456 and STS 593, with noteworthy post-coital antifertility properties in the rat were studied for their estrogenic, antiestrogenic, progestagenic, antiprogestagenic, antigonadotrophic, androgenic and antiandrogenic effects in laboratory animals. Beside their weak estrogenic activity which corresponds to their slight affinity to the uterine estrogen receptor in the rat, both steroids show remarkable antiestrogenic effects. No progestagenic, androgenic and antiandrogenic effects were found but STS 593 showed some antiprogestagenic activity. The antigonadotrophic efficacy of STS 456 was relatively high while STS 593 was scarcely active. The results are discussed with respect to possible application of these drugs for interceptive purposes.

Nonylphenol ethoxylates and their metabolites in sewage treatment plants and rivers of Tianjin, China

Nonylphenol polyethoxylates (NPnEO) and nonylphenol (NP) have provoked much environmental concern because of their weak estrogenic activities. We monitored NPnEO and their metabolites in rivers in Tianjin and in a sewage treatment plant of Tianjin monthly for 1 year. The total concentrations of NPnEO and NP in influent, up to 47.2 μg L −1 in August, were higher in summer than in other seasons. During the 12 months survey, NP was accumulated in most effluent samples with a mean value of 2.92 μg L −1. The average concentrations of nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO) and nonylphenol triethoxylate (NP3EO) in effluents were 1.26, 1.53 and 1.06 μg L −1, which corresponds to percent removals of 75%, 60% and 62%, respectively. In rivers of Tianjin, NP2EO and nonylphenoxyethoxy acetic acid (NP2EC) exhibited the highest concentrations in the surface water, up to 1.38 and 9.59 μg L −1, respectively. The pollution of nonylphenolic substances in sediments of Haihe River belongs to moderate or severe level in the world, with the total concentration between 4.1 and 9.9 μg g −1, dry weight.

Removal of Linear and Branched p-Alkylphenols from Aqueous Solution by Combined Use of melB Tyrosinase and Chitosan Beads

In this study, melB tyrosinase was applied for enzymatic removal of linear and branched p-alkylphenols from aqueous solutions. First, systematic studies were carried out to estimate the effects of the process parameters such as the temperature, pH value, and enzyme dose on quinone conversion of p-cresol as a model phenol compound. A variety of p-alkylphenols were removed from aqueous solutions through the tyrosinase-catalyzed quinone conversion and subsequent nonenzymatic adsorption of quinone derivatives on chitosan beads at pH 6.0 and 30 °C under the optimum conditions determined for p-cresol. The % removal values of 98–100 were obtained for p-n-alkylphenols. Branched p-alkylphenols with a weak estrogenic activity containing 4-tert-butylphenol and 4-tert-pentylphenol, which underwent no quinone conversion by commercially available mushroom tyrosinase in the absence of H2O2, were also effectively removed by further increasing either the melB tyrosinase concentration or the amount of added chitosan beads. The present technique is much effective in the fact that a series of reactions rapidly progress under mild conditions and the chitosan beads can be readily separated from the reaction medium after the enzymatic treatment.

Development of a radioimmunoassay for the measurement of Bisphenol A in biological samples

Bisphenol A (BPA) is widely used in the manufacturing of polycarbonate plastic food and drink packaging. Possessing a weak estrogenic activity, BPA is listed among a growing list of endocrine disrupting compounds. In this study, a polyclonal anti-BPA antibody was obtained by immunization with BPA-monocarboxymethylether covalently linked to BSA. The antibody demonstrates negligible cross-reactivity with most analogous BPA phenolic structures, and no cross-reactivity with endogenous steroids. An extraction step with ethyl acetate minimized matrix effects and allowed the BPA measurement in plasma and other biological samples. Recovery after loading test was 96 ± 4% and dilution tests had a linear profile ( r 2 > 0.93). The limit of detection of the BPA RIA was 0.08 μg L −1 with an IC50 of 1.25 μg L −1. The intra- and inter-assay coefficients of variation were 5.6 and 8.6%, respectively at a BPA concentration of 0.7 μg L −1 and 6.9 and 5.7% at a BPA concentration of 1.3 μg L −1. A significant correlation was found between the values obtained by the RIA and HPLC–MS ( r 2 = 0.92) or HPLC coupled to a fluorescence detector ( r 2 = 0.80). In conclusion, we described a BPA-RIA that is a suitable tool for evaluating human exposure to BPA.

Effect of Dendrophthoe falcata (L.f.) Ettingsh on female reproductive system in Wistar rats: a focus on antifertility efficacy

Background This study was designed to assess the effect of one traditionally used antifertility plant, Dendrophthoe falcata (L.f.) Ettingsh (Loranthaceae), on female reproductive system, fertility and safety, by oral administration to adult female Wistar rats. Study Design After the oral acute toxicity study, the hydroalcoholic extract of the aerial parts was administered at three doses. Treatment started at weaning and continued until Day 0 postpartum. Results The LD 50 value was found to be 4.55 g/kg body weight. Vaginal opening occurred earlier in treated females when compared with controls. Analysis of vaginal smears revealed that all animals were cycling, although the length of the diestrus was longer in treated groups. In postcoital testing, the extract was found to be more effective in causing significant anti-implantation activity and reduction in the number of litters born. The extract also exhibited weak estrogenic activity when given alone, and when given along with ethinyl estradiol, it exhibited slight antiestrogenic activity in immature ovariectomized rats. Conclusion All observations suggest that the extract has antifertility effect and is safe at effective doses employed in the study.

No Effect of Red Clover–Derived Isoflavone Intervention on the Insulin-Like Growth Factor System in Women at Increased Risk of Colorectal Cancer

Increased insulin-like growth factor (IGF)-I and IGF-II concentrations are related to increased colorectal cancer risk. Isoflavones have been associated with reduced colorectal cancer risk, and may affect the IGF system because of their weak estrogenic activity. The aim of the study was to investigate the effect of isolated isoflavones on serum concentrations of IGF system components. We conducted a randomized, placebo-controlled, double-blinded, crossover trial in four hospitals in the Netherlands to investigate the effect of an 8-week supplementation with red clover-derived isoflavones (84 mg/d) on serum IGF-I concentrations. In addition, serum concentrations of IGF-II and IGF binding proteins (IGFBP)-1, IGFBP-2, and IGFBP-3 were assessed. Normal colorectal tissue biopsies were obtained after the first intervention period and mRNA expression of IGF-I, IGF-II, IGFBP-3, and IGF-IR was evaluated. Our study population consisted of 34 postmenopausal women with a family history of colorectal cancer or a personal history of colorectal adenomas. Isoflavone supplementation did not significantly affect serum concentrations of total IGF-I (mean relative within-person difference; IGF-I, -2.0%; 95% confidence interval, -8.0% to 3.9%). IGF-II and IGFBPs were also not significantly altered after isoflavone supplementation. Colorectal tissue mRNA expression of IGF system components did not significantly differ between individuals on isoflavone supplementation and those who received placebo. The results of our trial, supported by a qualitative review of soy trials published to date, suggest that isoflavones do not significantly affect circulating levels of IGF system components. Increased levels of IGF-I, as observed in most of these trials, are likely due to simultaneous protein supplementation.

Do Soy Foods Affect Sperm Quality

Ample evidence in animals demonstrates that isoflavones, with their weak estrogenic activity, can negatively affect the male reproductive system, but

Determination of free and total bisphenol A in human urine to assess daily uptake as a basis for a valid risk assessment

Bisphenol A (BPA) is widely distributed and exhibits weak estrogenic activity. In contrast to BPA, the corresponding glucuronide metabolite is not estrogenic. Therefore, free and total BPA were determined in human urine samples to assess the significance of free BPA for risk assessment. In only 10% of 474 samples from 287 subjects was free BPA detected in a range from <LOD (0.3 μg/l) to 2.5 μg/l. Due to sample contamination with low amounts (∼1 μg/l) of BPA, house dust samples were independently collected in homes but not from persons who provide urine samples and analysed for BPA to check for potential sources of contamination. BPA was found in the range from 117 to 1 486 μg/kg (median: 553 μg/kg) dust. Additionally, BPA and d 16-BPA were administered to a volunteer to demonstrate the problem of contamination. In comparison to low levels of free BPA (<1.25 μg/l), no free d 16-BPA was observed. Therefore, the maximal concentration of 2.5 μg/l observed here may be considered as an exaggerated value as a result of contamination. Nevertheless, for risk assessment a concentration of 2.5 μg/l was used and this value is 800-fold below the tolerable daily intake (TDI) of 50 μg/kg. Total BPA was determined in 147 urine samples with concentrations between <LOD and 9.3 μg/l.

Cutaneous Penetration of Bisphenol A in Pig Skin

Bisphenol A (BPA) is an endocrine disruptor with weak estrogenic activity, used in epoxy resin and polycarbonate plastic. Human exposure may occur by contamination from food or food-contact material and by occupational scenarios. Occupational health hazards may be associated with allergic contact dermatitis (ACD) secondary to BPA exposure. Most ACD occurs in workers handling BPA products, such as plastic-product workers, and those exposed to epoxy adhesive tapes, foams, and dental products. The present study examined in vitro cutaneous penetration of BPA through pig skin, using a Franz cell. After 2, 5, and 10 h of exposure, total BPA skin content was 3, 6.9, and 11.4% of the applied dose, respectively. BPA remained essentially on the skin surface and penetration mainly accumulated in the dermis. As the pig skin model is a reliable predictor of percutaneous penetration in humans, these findings may be reassuring for workers in contact with BPA-based products.

Sediment–Porewater Partition of Nonylphenol Polyethoxylates: Field Measurements from Lanzhou Reach of Yellow River, China

Nonylphenol polyethoxylates (NPnEO) and nonylphenol (NP) have drawn much environmental concern because of their weak estrogenic activities. The present study focused on the spatial distribution of NPnEO and NP in surface sediments and their corresponding porewaters along Lanzhou Reach of Yellow River, China. Long EO chain NPnEO analogs with n > 2 were not measurable in most sediment and porewater samples, so only NP, nonylphenol monoethoxylate (NP1EO) and nonylphenol diethoxylate (NP2EO) were discussed in this study. Concentrations of NP, NP1EO, and NP2EO in the sediments ranged from 61.3 to 113.9, 31.1 to 55.9, and 47.9 to 74.1 ng/g dry weight, respectively. A significant correlation (R2= 0.56, p < 0.01) was observed between NP levels and organic carbon content of the sediments, whereas no correlation was found for the more hydrophilic NP1EO and NP2EO. The concentrations of NP, NP1EO, and NP2EO in the porewaters ranged from 0.35 to 1.95, 0.06 to 0.63, and 0.08 to 0.38 microg/L. The mean in situ log K(oc) values (n = 13, S1 excluded) of NP, NP1EO, and NP2EO were 4.48, 4.94, and 5.06, respectively, which were lower than those measured in batch adsorption experiments.

Reactivation of methylation-silenced tumor suppressor gene p16INK4a by nordihydroguaiaretic acid and its implication in G1 cell cycle arrest

Phytoestrogens, including the two major groups isoflavones and lignans, are chemicals with weak estrogenic activity which occur naturally in many foods and herbs. Recently, several intriguing studies reported that some isoflavones can affect DNA methylation status. However, little is known about the effect of plant lignans on epigenetic modification. Using cultured T47D and RKO human cancer cells as a model, we studied the modulating effects of nordihydroguaiaretic acid (NDGA), a member of the lignan family, on the methylation status of the gene promoter region. Our results indicated that NDGA reverses p16INK4a CpG island hypermethylation, and restores its transcription and expression in both cell lines. Cytometric analysis showed that NDGA significantly affects cell cycle progression by arresting cells at the G1 phase. Consistent with the reacquisition of p16INK4a expression, we also found that NDGA induces cellular senescence in cancer cells. This is the first study demonstrating that a member of the lignan family can induce demethylation in human cancer cell lines, suggesting a novel epigenetic mechanism in the prevention or treatment of cancer.

Continuous exposure to bisphenol A during in vitro follicular development induces meiotic abnormalities

Bisphenol A (BPA), a widely used environmental contaminant, may exert weak estrogenic, anti-androgenic and anti-thyroidic activities. BPA is suspected to possess aneugenic properties that may affect somatic cells and mammalian oocytes. Oocyte growth and maturation depend upon a complex bi-directional signaling between the oocyte and its companion somatic cells. Consequently, disturbances in oocyte maturation may originate either from direct effects of BPA at the level of the oocyte or from indirect influences at the follicular level, such as alterations in hormonal homeostasis. This study aimed to analyze the effects of chronic BPA exposure (3 nM to 30 μM) on follicle-enclosed growth and maturation of mouse oocytes in vitro. Oocytes were cultured and their spindle and chromosomes were stained by α-tubulin immunofluorescence and ethidium homodimer-2, respectively. Confocal microscopy was utilized for subsequent analysis. Only follicles that were exposed to 30 μM BPA during follicular development showed a slightly reduced granulosa cell proliferation and a lower total estrogen production, but they still developed and formed antral-like cavities. However, 18% of oocytes were unable to resume meiosis after stimulation of oocyte maturation, and 37% arrested after germinal vesicle breakdown, significantly different from controls ( p < 0.05). Only 45% of the oocytes extruded a first polar body ( p < 0.05). 30 μM BPA led also to a significant increase in meiosis I-arrested oocytes with unaligned chromosomes and spindle aberrations. Oocytes that were able to progress beyond meiosis I, frequently arrested at an abnormal telophase I. Additionally, in many oocytes exposed to low chronic BPA that matured to meiosis II chromosomes failed to congress at the spindle equator. In conclusion, mouse follicle culture reveals non-linear dose-dependent effects of BPA on the meiotic spindle in mouse oocytes when exposure was chronic throughout oocyte growth and maturation.

Endocrine effects of polycyclic musks: do we smell a rat?

Synthetic polycyclic musks are used extensively as fragrances and are released ubiquitously in our environment, particularly water. We have demonstrated that these compounds display very weak oestrogenic activity in vitro, although no obvious oestrogenic activity was found in young rats or zebrafish. We demonstrated, however, that the oestrogenic effect of these compounds is cell- and oestrogen receptor-type specific, raising the possibility that the in vivo models may have underestimated some effects. In addition, polycyclic musks were found to possess antioestrogenic (ERbeta-selective), antiandrogenic and antiprogestagenic activity. As recent research clearly demonstrates the possibility of endocrine disrupting environmental compounds to act in concert, more research to these combined effects is important. We have developed efficient methods to measure such combined bioactivities in a range of matrices using human cell-based reporter gene assays. So far, we found agonistic, rather than antagonistic, effects in water samples, suggesting a predominance of agonistic compounds in such samples.

The methoxychlor metabolite, HPTE, directly inhibits the catalytic activity of cholesterol side-chain cleavage (P450scc) in cultured rat ovarian cells

Exposure to the pesticide methoxychlor in rodents is linked to impaired steroid production, ovarian atrophy and reduced fertility. Following in vivo administration, it is rapidly converted by the liver to 2,2-bis-( p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE), the reported active metabolite. Both methoxychlor and HPTE have weak estrogenic and antiandrogenic activities, and these effects are thought to be mediated through the estrogen and androgen receptors, respectively. Previous in vivo studies on methoxychlor exposure to female animals have demonstrated decreased progesterone production but no change in serum estrogen levels. We recently showed that HPTE specifically inhibits the P450 cholesterol side-chain cleavage (P450scc, CYP11A1) step resulting in decreased androgen production by cultured rat testicular Leydig cells. The current studies examined the mechanism of action of HPTE on progesterone production by cultured ovarian cells (granulosa and theca-interstitial) from pregnant mare serum gonadotropin-primed immature rats. In addition, we evaluated whether the effects of HPTE on rat ovarian cell progesterone biosynthesis were mediated through the estrogen or androgen receptors. Exposure to HPTE (0, 10, 50 or 100 nM) alone progressively inhibited progesterone formation in cultured theca-interstitial and granulosa cells and the P450scc catalytic activity in theca-interstitial cells in a dose-dependent manner with significant declines starting at 50 nM. However, HPTE did not change mRNA levels of the P450scc system (P450scc, adrenodoxin reductase and adrenodoxin) as well as P450scc protein levels. Of interest, estradiol, xenoestrogens (bisphenol-A or 4- tert-octylphenol), a pure antiestrogen (ICI 182,780), or antiandrogens (4-hydroxyflutamide or the vinclozolin metabolite M-2), had no effect on progesterone production even at 1000 nM. Co-treatment of HPTE with ICI 182,780 did not block the effect of HPTE on progesterone formation. These studies suggest that the decline in progesterone formation following exposure to HPTE in cultured ovarian cells is associated with the inhibition of catalytic activity of P450scc at least in theca-interstitial cells. This action does not appear to be mediated through the estrogen or androgen receptor signaling pathways, and other chemicals exhibiting estrogenic, antiestrogenic or antiandrogenic properties do not mimic its effect on ovarian steroid production.

Bisphenol A induces permanent squamous change in mouse prostatic epithelium

Bisphenol A (BPA) is a monomer of plastic products widely used in daily life, and has weak estrogenic activity. In this study, male BALB/c mice were treated with BPA and diethylstilbestrol (DES) in adult and fetal periods to investigate whether BPA could affect prostatic epithelial differentiation. Eight-to 9-week-old mice treated for 3 weeks with subcutaneous implants of 0.2–200 mg BPA pellets induced the expression of cytokeratin 10 (CK10) in prostatic basal epithelial cells in a dose-dependent manner. Utilizing organ culture of adult prostate, 1 nM and 1 μM BPA also induced CK10 expression and squamous metaplasia with multilayering of basal epithelial cells, respectively. Fetal exposure to low-dose BPA (20 μg/kg/day) from gestation day (GD) 13 to GD18 induced permanent CK10 expression in basal cells of the adult prostate similar to DES (0.2 μg/kg/day). These results indicate that in mouse, BPA can directly elicit CK10 expression in prostatic epithelium, and that this change can be elicited by doses as low as 20 μg/kg/day. We speculate that low-dose BPA during fetal life may also induce permanent squamous change in human prostate.

Soy food and soy isoflavone intake in relation to semen quality parameters

Isoflavones are plant-derived polyphenolic compounds with weak estrogenic activity found mainly in soy beans and soy-derived products. High isoflavone intake has been related to decreased fertility in animals. However, human studies on the potential reproductive effects of isoflavones are limited. Thus, we explored the association of soy foods and soy isoflavones intake with semen quality parameters.

The Isoflavonoid Daidzein Attenuates the Oxidative Damage Induced by Polychlorinated Biphenyls on Cultured Chicken Testicular Cells

The soy isoflavonoid daidzein (DAI) is one of the most abundant phenolic compounds in the human diet and in animal feedstuffs. Daidzein possesses a wide spectrum of physiological and pharmacological functions related to human health. The aim of this study was to evaluate the effect of DAI on oxidative damage induced by a potential carcinogen, polychlorinated biphenyl. Testicular cells were dispersed from 18-d-old chicken embryos and exposed to DAI alone or in combination with a mixture of polychlorinated biphenyls, Aroclor 1254 (A1254), in culture. Oxidative damage was estimated by measuring the lipid peroxidation and superoxide dismutase activities and glutathione content. Results showed that DAI (10 μg/mL) increased germ cell numbers, which were inhibited by cotreatment with the estrogen receptor antagonist tamoxifen at 0.1 μg/mL. Exposure to A1254 (10 μg/mL) reduced superoxide dismutase activity and glutathione content but increased lipid peroxidation significantly. However, simultaneous supplementation with 10 μg/mL of DAI restored these parameters. The above results indicated that DAI may exert weak estrogenic activity, and more important, that DAI may display an antioxidant effect to prevent oxidative damage induced by the oxidant A1254.

Lack of a Significant Effect of Arctiin on Development of 7,12-dimethylbenz(a)anthracene-induced Mammary Tumors in Ovariectomized Sprague-Dawley Rats

: Arctiin, a plant lignan, is metabolized to hormone-like compounds with weak estrogenic and antioxidative activity in experimental animals and man. To clarify its influence on mammary carcinogenesis, female rats were administrated 7,12-dimethylbenz(a)anthracene (DMBA) once, and when the incidence of palpable mammary tumors reached 50%, subjected to ovariectomy (OVX) and divided into tumor-bearing [DMBA-Tumor (+)] and no-tumor-bearing [DMBA-Tumor (−)] groups, subgroups of each then being fed soybean-free diet containing 0, 40, 200, and 1000 ppm of arctiin for 31 wk. The incidence and multiplicity of palpable tumors in the 200 ppm DMBA-Tumor (+) subgroup from week 12 of arctiin treatment tended to be decreased as compared to the 0 ppm subgroup and at terminal sacrifice, the volume of histopathologically defined mammary tumors was decreased in the 40 ppm DMBA-Tumor (−) subgroup, but again without statistical significance. In conclusion, weak inhibitory effects of arctiin on DMBA-induced mammary tumor development were suggested in OVX rats, but any further assessment is needed to obtain conclusive results.