Electrochemistry detection of estrogenic effect: Regulation of de novo purine synthesis and catabolism by gibberellin and fulvestrant

The estrogenic effect of plant growth regulators has been received little attention, which leads to the lack of relevant toxicity data. In this study, the estrogenic effect induced by gibberellin with ERα-dependent manner was found by E-screen and western blot methods, and the electrochemical signals of MCF-7 cells regulated by gibberellin and fulvestrant were investigated. The results showed that the electrochemical signals of MCF-7 cells were increased by gibberellin, while reduced by fulvestrant significantly, and displayed an extremely sensitive response to the effects of estrogenic effect induced by ERα agonist and antagonist. Western blot results showed that the expressions of phosphoribosyl pyrophosphate amidotransferase and hypoxanthine nucleotide dehydrogenase in de novo purine synthesis and adenine deaminase in catabolism were more effective regulated by gibberellin and fulvestrant, resulting in significant changes of the levels of guanine, hypoxanthine and xanthine in cells, and then electrochemical signals. The results provide a theoretical basis for the establishment of new electrochemical detection method of the estrogenic effect of plant regulators.

Activation of estrogen-related receptor: An alternative mechanism of hexafluoropropylene oxide homologs estrogenic effects

Perfluorooctanoic acid (PFOA) alternatives such as hexafluoropropylene oxide homologs (HFPOs) cause concern due to increased occurrence in the environment as well as potential bioaccumulation and toxicity. HFPOs have been demonstrated to activate the estrogen receptor (ER) pathway. The ER pathway is homologous and connected to the estrogen-related receptor (ERR) pathway, but HFPOs effects on the ERR pathway have not been studied. Hence, we assessed the potential estrogenic effects of HFPOs via ERRγ pathway. In vitro assays revealed that HFPO dimeric, trimeric, and tetrameric acids (HFPO-DA, -TA, and -TeA, respectively), acted as ERRγ agonists, activating the transcription of both human and zebrafish ERRγ at low concentrations, but inhibiting zebrafish ERRγ at high concentrations. We also found that HFPO-TA promoted the human endometrial cancer cells (Ishikawa cells) proliferation via ERRγ/EGF, Cyclin D1 pathway. The HFPO-TA-induced proliferation of Ishikawa cells was inhibited by co-exposure with a specific antagonist of ERRγ, GSK5182. In vivo exposure of female zebrafish to HFPO-TA disturbed sex hormone levels, interfered with the gene expression involved in estrogen synthesis and follicle regulation, and caused histopathological lesions in the ovaries, which were similar to those induced by a known ERRγ agonist GSK4716. Taken together, this study revealed a new mechanism concerning the estrogenic effect of HFPOs via activation of the ERRγ pathway.

Twelve natural estrogens and ten bisphenol analogues in eight drinking water treatment plants: Analytical method, their occurrence and risk evaluation

Bisphenol analogues (BPs) and natural estrogens (NEs) as two important groups of endocrine-disrupting compounds (EDCs) in drinking water treatment plants (DWTPs) have been hardly investigated except bisphenol A (BPA) and three major NEs including estrone (E1), 17β-estradiol (E2) and estriol (E3). In this study, a GC-MS analytical method was firstly established and validated for trace simultaneous determination of ten BPs and twelve NEs in drinking water, which included BPA, bisphenol B (BPB), bisphenol C (BPC), bisphenol E (BPE), bsiphenol F (BPF), bsiphenol P (BPP), bisphenol S (BPS), bisphenol Z (BPZ), bisphenol AF (BPAF), bisphenol AP (BPAP), E1, E2, E3, 17α-estradiol (17α-E2), 2-hydroestrone (2OHE1), 16hydroxyestrone (16α-OHE1), 4-hydroestrone (4OHE1), 2-hydroxyesstradiol (2OHE2), 4-hydroxyestradiol (4OHE2), 17-epiestriol (17epiE3), 16-epiestriol (16epiE3) and 16keto-estraiol (16ketoE2). This investigation showed that eighteen out of twenty-two targeted compounds were detected in drinking source waters of eight DWTPs with concentrations ranging from not detected to 142.8 ng/L. Although the conventional treatment process of DWTP could efficiently remove both BPs and NEs with respective removal efficiencies of 74.1%-90.9% and 74.5%-100%, BPA, BPS, BPE, BPZ, E1, 2OHE1, and 2OHE2 were found in the finished drinking waters. Chlorination could remove part of BPs and NEs, but the efficiency varied greatly with DWTP and the reason was unknown. In the finished drinking waters of eight DWTPs, the highest chemically calculated estrogen equivalence (EEQ) derived from BPs and NEs was up to 6.11 ngE2/L, which was over 22 times that could do harm to zebrafish, indicating a potential risk to human health. Given the fact that many chlorination products of BPs and NEs likely have higher estrogenic activities, the estrogenic effect of BPs and NEs in finished drinking water should be accurately examined urgently with the inclusion of BPs, NEs as well as their main chlorinated by-products. This study shed new light on the occurrence, removal, and potential estrogenic effects of BPs and NEs in DWTPs.

Comparative in vitro and in silico study on the estrogenic effects of 2,2-bis(4-chlorophenyl)ethanol, 4,4'-dichlorobenzophenone and DDT analogs

DDT and its transformation products (DDTs) are frequently detected in environmental and biological media. Research suggests that DDT and its primary metabolites (DDD and DDE) could induce estrogenic effects by disturbing estrogen receptor (ER) pathways. However, the estrogenic effects of DDT high-order transformation products, and the exact mechanisms underlying the differences of responses in DDT and its metabolites (or transformation products) still remain unknown. Here, besides DDT, DDD and DDE, we selected two DDT high-order transformation products, 2,2-bis(4-chlorophenyl) ethanol (p,p'-DDOH) and 4,4'-dichlorobenzophenone (p,p'-DCBP). We aim to explore and reveal the relation between DDTs activity and their estrogenic effects by receptor binding, transcriptional activity, and ER-mediated pathways. Fluorescence assays showed that the tested 8 DDTs bound to the two isoforms (ERα and ERβ) of ER directly. Among them, p,p'-DDOH exhibited the highest binding affinity, with IC₅₀ values of 0.43 μM and 0.97 μM to ERα and ERβ, respectively. Eight DDTs showed different agonistic activity toward ER pathways, with p,p'-DDOH exhibiting the strongest potency. In silico studies revealed that the eight DDTs bound to either ERα or ERβ in a similar manner to 17β-estradiol, in which specific polar and non-polar interactions and water-mediated hydrogen bonds were involved. Furthermore, we found that 8 DDTs (0.0008-5 μM) showed distinct pro-proliferative effects on MCF-7 cells in an ER-dependent manner. Overall, our results revealed not only for the first time the estrogenic effects of two DDT high-order transformation products by acting on ER-mediated pathways, but also the molecular basis for differential activity of 8 DDTs.

Endocrine disrupting effect and reproductive toxicity of the separate exposure and co-exposure of nano-polystyrene and diethylstilbestrol to zebrafish

The co-occurrence of nanoplastics and other pollutants in the environment has gotten a lot of attention, but information on the biological toxicity of their co-exposure was limited. This study aims to reveal the endocrine disrupting effect and reproductive toxicity of nano-polystyrene (NPS) and diethylstilbestrol (DES) to zebrafish under separate and combined exposure. Results indicated that NPS and DES exposure in isolation reduced the hepatosomatic index and gonadosomatic index, and altered the cell maturity in gonads in both cases. Even worse, the co-exposure of NPS and DES exacerbated the damage to the liver and gonads of fish. The two pollutants individually inhibited the secretion of sex hormones and vitellogenin. The inhibition effect of DES was especially dose-dependent, while NPS had weaker effect than DES. Their combined action on the secretion of sex hormones and vitellogenin exhibited additive effect. However, NPS did not affect the content of thyroid hormones in fish, and also had no significant effect on the reduction of thyroid hormone caused by DES exposure. Furthermore, their co-exposure decreased the cumulative eggs from 1031 to 306, and the spawning number from 12 to 8. The fertilization rate and hatchability rete of eggs were reduced by 30.9% and 40.4%, respectively. The abnormality rate of embryos was 65.0%, significantly higher than in separate DES and NPS groups (55.7% and 30.8% respectively). The abnormal development of offspring was mainly pericardial cyst, spinal curvature, and growth retardation.

Assessing the toxicity of bisphenol A and its six alternatives on zebrafish embryo/larvae

Bisphenol A (BPA) analogues are gradually replacing BPA in the plastics industry. Whether these alternatives are indeed safer than BPA itself, however, remains unclear. Here, we studied the toxicity of BPA and six of its alternatives-BPB, BPC, BPE, BPF, BPAF, and BPAP-using zebrafish embryos/larvae. According to their half lethal concentration (LC₅₀) values, the acute toxicity of BPA and six alternative bisphenols to zebrafish embryos, from highest to lowest, was BPAP ≈ BPAF > BPC > BPB > BPA > BPE > BPF. Under nonlethal concentrations, the tested bisphenols had different toxic effects on development in terms of reducing the hatching rate, frequency of spontaneous movements, and heart rate in the embryo, as well as inducing yolk sac edema, pericardial edema, and spinal deformation in the larvae. The estrogenic activity of BPE, BPF, and BPAF was higher than that of BPA, as shown by vtg1 expression assays. Moreover, BPA and its alternatives increased SOD activity and cell apoptosis in embryos/larvae under nonlethal concentrations. Our findings indicate that BPA alternatives may not be safer than BPA in zebrafish, and that these BPA alternatives should be applied with caution.

Occurrence, spatial distribution, and main source identification of ten bisphenol analogues in the dry season of the Pearl River, South China

Bisphenol analogues (BPs) including bisphenol a (BPA) have been broadly utilized as industrial feedstocks and unavoidably discharged into water bodies. However, there is little published data on the occurrence, distribution, and environmental risks of other BPs in surface water. In this study, ten BPs besides BPA were analyzed in surface water from the Pearl River, South China. Among these detected BPs, BPA, bisphenol F (BPF), bisphenol AF (BPAF), and bisphenol S (BPS) were the most frequently detected compounds. The median concentrations of the measured BPs were ranked in the order of BPA (34.9 ng/L) > BPS (24.8 ng/L) > BPAF (10.1 ng/L) > bisphenol F (BPF) (9.0 ng/L) > bisphenol B (BPB) (7.6 ng/L) > bisphenol C (BPC) (1.2 ng/L). Among them, BPA and BPS were predominant BPs, contributing 68% of the total ten BPs in surface water of the Pearl River. These results demonstrated that BPA and BPS were the most extensively utilized and manufactured BPs in this region. The source analysis of BPs suggested that the BPs may be originated from domestic wastewater, wastewater treatment plant (WWTP) effluent, and the leaching of microplastic in surface water of the Pearl River. The calculated BP-derived estrogenic activity exhibited low to medium risks in surface water, but their combined estrogenic effects with other endocrine disrupting compounds should not be ignored.

Transgenerational effects of androstadienedione and androstenedione at environmentally relevant concentrations in zebrafish (Danio rerio)

Androgens androstadienedione (ADD) and androstenedione (AED) are predominant steroid hormones in surface water, and can disrupt the endocrine system in fish. However, little is known about the transgenerational effects of ADD and AED in fish. In the present study, F0 generation was exposed to ADD and AED from 21 to 144 days post-fertilization (dpf) at nominal concentrations of 5 (L), 50 (M) and 500 (H) ng L^-1, and F1 generation was domesticated in clear water for 144 dpf. The sex ratio, histology and transcription in F0 and F1 generations were examined. In the F0 generation, ADD and AED tended to be estrogenic in zebrafish, resulting in female biased zebrafish populations. In the F1 generation, ADD at the H level caused 63.5% females, while AED at the H level resulted in 78.7% males. In brain, ADD and AED had similar effects on circadian rhythm in the F0 and F1 generations. In the F1 eleutheroembryos, transcriptomic analysis indicated that neuromast hair cell related biological processes (BPs) were overlapped in the ADD and AED groups. Taken together, ADD and AED at environmentally relevant concentrations had transgenerational effects on sex differentiation and transcription in zebrafish.

Experimental and molecular docking studies of estrogen-like and anti-osteoporosis activity of compounds in Fructus Psoraleae

ETHNOPHARMACOLOGICAL RELEVANCE

Fructus Psoraleae (FP), dry mature fruits of Cullen corylifolium (L.) Medik., has been used clinically to treat kidney yang deficiency-induced impotence, asthma and cold pain in waist and knee caused by kidney deficiency. A study of the source of the significant kidney-enhancing effect of FP revealed that it may be due to its strong estrogen-like activity.

AIM OF THE STUDY

This study aimed to investigate the estrogen-like activity of the FP extract and 13 bioactive compounds in it, as well as the mechanisms underlying their estrogen-like and anti-osteoporosis activities.

MATERIALS AND METHODS

The estrogen-like activities of the 75% ethanol-only FP extract, and 75% ethanol plus petroleum ether, ethyl acetate, n-butanol or water FP extracts were each measured using Cell Counting Kit-8 (CCK-8) and luciferase reporter gene assays. The compounds were identified by high-performance liquid chromatography analysis. The activation of estrogen receptor signaling by the compounds was compared with that by estradiol (E₂) using the molecular docking software MOE-Dock 2008.10. The activation of the ER-Wnt-β-catenin signaling pathway was investigated using an alkaline phosphatase (ALP) assay, qPCR analysis and Western blot analysis.

RESULTS

The results revealed that the 75% ethanol plus ethyl acetate extract showed the highest estrogen-like activity among the four 75% ethanol extract fractions (further extracted with petroleum ether, ethyl acetate, n-butanol or water). Some compounds in FP showed strong estrogenic effect and anti-osteoporosis activity, and activated the Wnt-β-catenin pathway. The isoflavone compound was the most active.

CONCLUSIONS

This study demonstrated that FP has a strong estrogen-like activity and some of its component compounds have anti-osteoporosis activity by activating the ER-Wnt-β-catenin signaling pathway. Our detections provide a new insight into the mechanisms underlying the estrogen-like and anti-osteoporosis activities of FP, as well as a better understanding of structure effects.

Environmental Estrogens and Their Biological Effects through GPER Mediated Signal Pathways

Many environmental chemicals have been found to exert estrogenic effects in cells and experimental animals by activating nuclear receptors such as estrogen receptors and estrogen-related receptors. These compounds include bisphenols, pesticides, polybrominated diphenyl ethers (PBDEs), organophosphate flame retardants, phthalates and metalloestrogens. G protein-coupled estrogen receptor (GPER) exists widely in numerous cells/tissues of human and other vertebrates. A number of studies have demonstrated that GPER plays a vital role in mediating the estrogenic effects of environmental pollutants. Even at very low concentrations, these chemicals may activate GPER pathways, thus affect many aspects of cellular functions including proliferation, metastasis and apoptosis, resulting in cancer progression, cardiovascular disorders, and reproductive dysfunction. This review summarized the environmental occurrence and human exposure levels of these pollutants, and integrated current experimental evidence toward revealing the underlying mechanisms of pollutant-induced cellular dysfunction via GPER. The GPER mediated rapid non-genomic actions play an important role in the process leading to the adverse effects observed in experimental animals and even in human beings.

Effects of Phenanthrene Stress on Gonads and Vitellogenin of Loach (Misgurnus anguillicaudatus)

Phenanthrene (PHE) as a tricyclic polycyclic aromatic hydrocarbon is one of the common pollutants in water and sediments, which can cause reproductive toxicity to aquatic organisms. In this study, enzyme-linked immunosorbent assay (ELISA) was used to detect the vitellogenin (VTG) of loach, and then to explore the estrogenic toxicity effect of PHE on loach. The results were as follows: (1) with the increase of PHE concentrations and the extension of exposure time, the gonadosomatic index (GSI) of males decreased significantly, while it increased in female loaches. In addition, males had more obvious changes than females and were more sensitive to PHE. (2) The increase of VTG contents in serum of males were stronger than that in females. Those results reveal that PHE has estrogenic effect, which can affect the generation of VTG, thus causing damage to the gonad development of loach.

Assessment of in vivo estrogenic and anti-inflammatory activities of the hydro-ethanolic extract and polyphenolic fraction of parsley (Petroselinum sativum Hoffm.)

ETHNOPHARMACOLOGICAL RELEVANCE

Since the dawn of time, medicinal and aromatic plants (AMPs) represent a precious heritage for humanity, especially in developing countries, who exploit their virtues in traditional pharmacopoeia to cope with health problems such as diabetes, kidney stones, ulcer, and digestive disorders. Petroselinum sativum Hoffm. belongs to Apiaceae family. It is traditionally used to treat arterial hypertension, diabetes, cardiac disease, renal disease, and recently reported as a plant endowed with a female anti-infertility effect.

AIM OF THE STUDY

This study aims to evaluate the in vivo effect of hydro-ethanolic extract and polyphenols of Petroselinum sativum Hoffm. on cholesterol, protein and estrogen levels, and characterize the chemical composition of polyphenolic fraction. In addition, acute toxicity and anti-inflammatory activity of tested extract was also investigated.

MATERIALS AND METHODS

Chemical composition of polyphenolic fraction was determined using High-Performance Liquid Chromatography with Diode-Array Detection (HPLC-DAD). First, toxicological investigations including sub-acute toxicity were performed by measuring animals' weights daily for four weeks. Afterwards, histopathological examination of livers and kidneys, and serum assay of ASAT and ALAT were also checked. Next, the acute in vivo anti-inflammatory study of the hydro-ethanolic extract and polyphenols of Petroselinum sativum Hoffm. versus Indomethacin was conducted. Furthermore, we evaluated the estrogenic effect of its hydro-ethanolic extract and the polyphenolic fraction following biochemical assays for the determination of proteins, cholesterol and estrogen levels.

RESULTS

The results revealed the presence of some phenolic compounds mainly ferulic acid, gallic acid and quercetin. Petroselinum sativum Hoffm. extracts also showed no evidence of hepatotoxicity nor nephrotoxicity, with remarkable anti-inflammatory activity, as well as a significant estrogenic effect compared to negative control.

CONCLUSION

This study provides a scope of the potential use of Petroselinum sativum Hoffm. extracts in counteracting female infertility issues.

Dioxybenzone triggers enhanced estrogenic effect via metabolic activation: in silico, in vitro and in vivo investigation

Dioxybenzone is widely used in cosmetics and personal care products and frequently detected in multiple environmental media and human samples. However, the current understanding of the metabolic susceptibility of dioxybenzone and the potential endocrine disruption through its metabolites in mimicking human estrogens remains largely unclear. Here we investigated the in vitro metabolism of dioxybenzone, detected the residue of metabolites in rats, and determined the estrogenic disrupting effects of these metabolites toward estrogen receptor α (ERα). In vitro metabolism revealed two major metabolites from dioxybenzone, i.e., M1 through the demethylation of methoxy moiety and M2 through hydroxylation of aromatic carbon. M1 and M2 were both rapidly detected in rat plasma upon exposure to dioxybenzone, which were then distributed into organs of rats in the order of livers > kidneys > uteri > ovaries. The 100 ns molecular dynamics simulation revealed that M1 and M2 formed hydrogen bond to residue Leu387 and Glu353, respectively, on ERα ligand binding domain, leading to a reduced binding free energy. M1 and M2 also significantly induced estrogenic effect in comparison to dioxybenzone as validated by the recombinant ERα yeast two-hybrid assay and uterotrophic assay. Overall, our study revealed the potential of metabolic activation of dioxybenzone to induce estrogenic disrupting effects, suggesting the need for incorporating metabolic evaluation into the health risk assessment of benzophenones and their structurally similar analogs.

Prevalent phthalates in air-soil-vegetable systems of plastic greenhouses in a subtropical city and health risk assessments

Wide use of plastic greenhouses for vegetable production increases human exposure to phthalate (PAEs) through vegetable intake. However, little information is available about distribution of PAEs in air-soil-vegetable systems of plastic greenhouses and PAE estrogenic effects. This study was designed to investigate PAE distributions and corresponding health risk in plastic greenhouses in Guangzhou, a subtropical city in South China. PAEs were prevalent in plastic greenhouses, with sum concentrations of 16 PAE compounds (∑16PAEs) up to 5.76 mg/kg in soils, 5.27 mg/kg in vegetables and 4393 ng/m³ in air. Di (2-ethylhexyl) phthalate, di-isobutyl phthalate, and dibutyl phthalate were predominant compounds. Average concentrations and bioconcentration factor of ∑16PAEs and the predominant PAE compounds in vegetables of greenhouses were higher than those of open fields. Plastic greenhouses exhibited significantly higher air PAE levels than those of open fields due to higher indoor temperature, which enhanced PAE accumulation by vegetables. Both carcinogenic and non-carcinogenic risks of PAEs via dietary and non-dietary exposures for farmers decreased with an order of vegetable > air > soil. Consumption of vegetables from greenhouses resulted in significantly higher estrogenic effects compared to those from open field cultivation. This study emphasizes highly potential health risks of PAEs in air-soil-vegetable systems of plastic greenhouses.

Tricresyl phosphate isomers exert estrogenic effects via G protein-coupled estrogen receptor-mediated pathways

Tricresyl phosphates (TCPs), as representative aromatic organophosphate flame retardants (OPFRs), have received much attention due to their potential neurotoxicity and endocrine-disrupting effects. However, the role of estrogen receptor α (ERα) and G protein-coupled estrogen receptor (GPER) in their estrogen disrupting effects remains poorly understood. Therefore, in this study, three TCP isomers, tri-o-cresyl phosphate (ToCP), tri-m-cresyl phosphate (TmCP) and tri-p-cresyl phosphate (TpCP), were examined for their activities on ERα by using two-hybrid yeast assay, and action on GPER by using Boyden chamber assay, cAMP production assay, calcium mobilization assay and molecular docking analysis. The results showed that three TCP isomers were found to act as ERα antagonists. Conversely, they had agonistic activity on GPER to promote GPER-mediated cell migration of MCF7 cells and SKBR3 cells. Both ToCP and TpCP activated GPER-mediated cAMP production and calcium mobilization, whereas TmCP had different mode of action, it only triggered GPER-mediated calcium mobilization, as evidenced by using the specific GPER inhibitor (G15) and GPER overexpressing experiments. Molecular docking further revealed that the way of interaction of TmCP and TpCP with GPER was different from that of ToCP with GPER, and higher activity of ToCP in activating GPER-mediated pathways might be associated with the alkyl substitution at the ortho position of the aromatic ring. Our results, for the first time, found a new target, GPER, for TCPs exerting their estrogen-disrupting effects, and demonstrated complex estrogen-disrupting effects of three TCP isomers involved their opposite activities toward ERα and GPER.

Unexpected culprit of increased estrogenic effects: Oligomers in the photodegradation of preservative ethylparaben in water

Widespread occurrence of emerging organic contaminants (EOCs) in water have been explicitly associated with adverse effects on human health, therefore representing a major risk to public health. Especially the increased toxicity is frequently observed during the photodegradation of EOCs in natural water, and even wastewater treatment plants. However, the culprit of increased toxicity and formation mechanism has yet to be recognized regarding the estrogenic activity. In this study, by combining laboratory experiments with quantum chemical calculations, the induction of human estrogenic activity was investigated using the yeast two-hybrid reporter assay during the photodegradation of preservatives ethylparaben (EP), along with identification of toxic products and formation mechanisms. Results showed that the increase in estrogenic effect was induced by photochemically generated oligomers, rather than the expected OH-adduct. The maximum estrogenic activity corresponded to the major formation of oligomers, while OH-adducts were less than 12%. Two photochemically generated oligomers were found to contribute to estrogenic activity, produced from the cleavage of excited triplet state molecules and subsequent radical-radical reactions. Computational toxicology results showed that the increased estrogenic activity was attributed to oligomer [4-Hydroxy-isophthalic acid 1-ethyl ester 3-(4-hydroxy-phenyl)] and its EC₅₀ was lower than that of the parent EP. In contrast, OH-adducts exhibited higher EC₅₀ values than the parent EP, while still possessing estrogenic activity. Therefore, more attention should be paid to these photodegradation products of EOCs, including OH-adducts.

2,4-Dichlorophenol induces feminization of zebrafish (Danio rerio) via DNA methylation

2,4-Dichlorophenol (2,4-DCP) is a ubiquitous contaminant of aquatic environments with an estrogenic effect on fish. However, the molecular mechanism underlying this effect remains elusive. To this end, the present study aimed to explore the effect of 2,4-DCP on sex differentiation and its relevant mechanism in zebrafish (Danio rerio). The results showed that a female-biased sex ratio was induced after exposing larval zebrafish to 2,4-DCP (0-160 μg/L) from 20 to 50 days post fertilization (dpf). The feminization of zebrafish was accompanied by decreased expression of male-related genes (sox9a, amh and dmrt1) under 2,4-DCP from 20 to 50 dpf. However, the expression of female-related genes (cyp19a1a, foxl2 and esr1) was also suppressed. Nevertheless, it is noteworthy that the methylation level of sox9a promoter was significantly increased, which may result in the significantly decreased expression of sox9a and ultimately the feminization effect of 2,4-DCP on zebrafish. In addition, 5-aza-2'-deoxycytidine (5-AZA), a methyltransferase inhibitor, significantly reduced the methylation level, increased the expression of sox9a, and partly impaired the feminization effect caused by 2,4-DCP, which further confirmed the importance of DNA methylation of sox9a in 2,4-DCP-induced feminization. These findings provide novel insights into the epigenetic mechanisms of DCP-induced estrogenic effect in fish.

Blooming cyanobacteria alter water flea reproduction via exudates of estrogen analogues

Cyanobacteria blooms are increasing globally, with further increases predicted in association with climate change. Recently, some cyanobacteria species have been identified as a source of estrogenic effects in aquatic animals. To explore possible estrogenic effects of Microcystis aeruginosa (an often-dominant cyanobacteria species) on zooplankton, we examined effects of cyanobacteria exudates (MaE, 2 × 10⁴ and 4 × 10⁵ cells/ml) on reproduction in Daphnia magna. We analyzed physiological, biochemical and molecular characteristics of exposed Daphnia via both chronic and acute exposures. MaE at both low and high cell density enhanced egg number (15.4% and 23.3%, respectively) and reproduction (37.7% and 52.4%, respectively) in D. magna similar to 10 μg/L estradiol exposure. In addition, both MaE of low and high cell densities increased population growth rate (15.8% and 19.6%, respectively) and reproductive potential (60% and 83%, respectively) of D. magna. These exudates promoted D. magna reproduction by stimulating 17β-hydroxysteroid-dehydrogenase (17β-HSD) activity and production of ecdysone and juvenile hormone, and by enhancing vitellogenin biosynthesis via up-regulating expression of Vtg1 and Vtg2. However, increased expression (6.6 times higher than controls) of a detoxification gene (CYP360A8) indicated that MaE might also induce toxicity in D. magna. Reproductive interference of zooplankton by blooming cyanobacteria might negatively affect foodwebs because MaE-induced zooplankton population increase would enhance grazing and reduce abundance of edible algae, thereby adding to the list of known disruptive properties of cyanobacterial blooms.

Applicability of the OECD 455 in-vitro assay for determination of hERa agonistic activity of isoflavonoids

The Organisation for Economic Co-operation and Development (OECD)-validated transactivation assay using the human estrogen receptor alpha (hERα) Hela9903 cell line is used for activity evaluation of hERα agonists and antagonists. Due to many advantages, this assay is broadly used as an initial screening process. However, response significantly higher from that of 17-β estradiol (E2) was observed with phytoestrogens for concentrations commonly above 1 μM in previous studies. The main aim of this study was thus to ascertain the applicability of OECD protocol 455 for evaluation of estrogenic activity of natural flavonoids, including known phytoestrogens. The estrogenic activities of aglycones as well as of O-methylated and glycosylated flavonoids were evaluated. Supra-maximal luciferase activity was seen for most of the flavonoids tested at concentrations even below 1 μM. hERα-mediated luciferase expression was confirmed with the competition assay specified in OECD protocol 455. However, at concentrations above 1 μM, non-specific interactions were also observed. Instead of EC₅₀ values, which could not be determined for most of the isoflavonoids tested, the concentrations corresponding to 10% (PC₁₀) and 50% (PC₅₀) of the maximum activity of the positive control, E2, were used for quantitative determination of estrogenic activities. Appropriate evaluation of the data obtained with the current OECD protocol 455 validated assay represents a valuable tool for initial screening of natural flavonoids for estrogenic activity.

Endocrine disrupting effects in western mosquitofish Gambusia affinis in two rivers impacted by untreated rural domestic wastewaters

Domestic wastewaters are an important source of endocrine disrupting chemicals in the receiving aquatic environment. Most rural domestic wastewaters (RDWs) in China have been directly discharged into the aquatic environment without any treatment. Here we studied the effects of RDWs on the western mosquitofish (Gambusia affinis) from two rural rivers receiving untreated RDWs. Mosquitofish samples were collected at 5 sampling sites along two rivers during dry and wet seasons. Sex ratios, secondary sex characteristics and transcriptional levels of target genes related to the endocrine system in adult females and males were determined. In parallel, various pollutants including steroid hormones, phenolic compounds, pesticides, polycyclic aromatic hydrocarbons (PAHs) and heavy metals were measured in the water samples at all sites. The results showed that the androgenic effects in the fish were evidenced by significant increase in male to female ratio in fish populations at two sampling sites and by the presence of modified hemal spines in females at four sampling sites when compared to the reference site. The males from the two rivers had increased Vtg mRNA expressions with a maximal 6.2-fold increase relative to the reference site and a delayed development of hemal spines. The redundancy analysis (RDA) showed that some physiological parameters were related to steroid hormones, phenolic compounds and PAHs. The findings from this study suggest that RDWs can lead to masculinization in females and feminization in males.

Steroidal and phenolic endocrine disrupting chemicals (EDCs) in surface water of Bahe River, China: Distribution, bioaccumulation, risk assessment and estrogenic effect on Hemiculter leucisculus

This study investigated selected steroidal and phenolic endocrine disrupting compounds (EDCs) in the surface water of the Bahe River (China) using gas chromatography mass spectrometry (GC-MS). Their effect on the wild sharpbelly Hemiculter leucisculus was investigated. The concentrations of 4-t-octylphenol, nonylphenol, bisphenol-A, estrone, 17 β-estradiol, 17 α-Ethinylestradiol, and estriol were up to 126.0, 634.8, 1573.1, 55.9, 23.9, 31.5, and 5.2 ng L^-1 in the surface water, and up to 26.4, 103.5, 146.9, 14.2, 9.3, 13.8, and 1.3 ng g^-1 in the fish muscle tissue, respectively. High estrogen equivalent levels and hazard quotients were found in the middle and lower reaches of the river, and the pollution in these regions caused enhanced growth conditions, inhibition of gonad growth, and suppression of spermatogenesis in H. leucisculus. The up-regulation of Vitellogenin mRNA expression in male fish, collected from relatively heavily EDCs contaminated areas, indicates a potential estrogenic effect. The differential expression profiles of genes related to steroidogenesis at all sampling sites suggests that these endpoints may play an important role for the pollution monitoring of estrogenic EDCs in the Bahe River.

Estrogenic potency of MC-LR is induced via stimulating steroidogenesis: In vitro and in vivo evidence

Waterborne microcystin-LR (MC-LR) has been reported to disrupt sex hormones, while its estrogenic potency remains controversial. We hypothesized that MC-LR could induce estrogenic effects via disrupting sex hormone synthesis, and verified this hypothesis by in vitro and in vivo assays. Effects of MC-LR (1, 10, 100, 500, 1000 and 5000 μg/L) on steroidogenesis were assessed in the H295R cells after 48 h. The contents of 17β-estradiol (E2) and testosterone (T) increased in a non-dose-dependent manner, which showed positive correlations with the expression of steroidogenic genes. In the in vivo assay, adult male zebrafish were exposed to 0.3, 1, 3, 10 and 30 μg/L MC-LR for 30 d. Similarly, E2 and T contents in the testis were increased, accompanied by extensive up-regulation of steroidogenic genes, especially cyp19a. Meanwhile, the percentage of spermatid in the testis declined. In the liver, the vtg1 gene was significantly up-regulated while both the transcriptional and protein levels of the estrogenic receptor (ER) declined. These results indicate that MC-LR induced non-dose-dependent estrogenic effects at environmental concentrations, which may result from steroidogenesis stimulation via a non-ER-mediated pathway. Our findings support a paradigm shift in the risk assessment of MC-LR from traditional toxicity to estrogenic risk, particularly at low concentrations, and emphasize the potential threat to the male reproductive capacity of wildlife in bloom areas.

Estrogenic activity of constituents from the rhizomes of Rheum undulatum Linné

Stilbenes have been reported to be phytoestrogen compounds owing to its structural similarity to the estrogenic agent diethylstilbestrol. To find new stilbene-derivative phytoestrogens, isolation of stilbene-rich R. undulatum was performed and led to identify six new compounds (1-5 and 28), one newly determined absolute configurations compound (27) together with 21 previously reported compounds (6-26). The structures of compounds were determined on the basis of extensive spectroscopic methods including 1D and 2D NMR and CD spectra data. All the isolated compounds were tested for their estrogenic activities in HepG2 cells transiently transfected with ERα, ERβ and ERE-reporter plasmid. Among them, stilbene-derivatives, piceatannol 3'-O-β-d-xylopyranoside (12), cis-rhaponticin (16) and rhapontigenin 3'-O-β-d-glucopyranoside (17), showed the more potent binding affinity for estrogen receptors than 17β-estrodiol.

Evaluating estrogenic and anti-estrogenic effect of endocrine disrupting chemicals (EDCs) by zebrafish (Danio rerio) embryo-based vitellogenin 1 (vtg1) mRNA expression

By measuring the vitellogenin 1 (vtg1) expression through quantitative PCR and in situ hybridization, we used the zebrafish embryo as an in vivo model to access the estrogenic or anti-estrogenic effects of several endocrine disrupting chemicals (EDCs), such as natural estrogen 17β-estradiol (E2), estriol (E3), synthetic hormones including diethylstilbestrol (DES), 4-octyl phenol (OP), bisphenol A (BPA), tamoxifen (TMX) and 3-(2,3-dibromopropyl) isocyanurate (TBC). According to our data, the estrogenic effect of the tested chemicals was ranked as: DES>E₂>E₃>OP>BPA, which is consistent with various in vivo and in vitro models. Therefore, the measurement of vtg1 gene expression in zebrafish embryos would be a valuable method for screening EDCs including both environmental estrogens and anti-estrogens.

Chlorination of bisphenol F and the estrogenic and peroxisome proliferator-activated receptor gamma effects of its disinfection byproducts

The reaction kinetics and transformation pathways between bisphenol F (BPF) and sodium hypochlorite were investigated at pH values ranging from 6.5 to 8.5 and with different initial concentration ratios. The reaction rate was pH- and free available chlorine (FAC)-dependent: the reaction rate at pH 8.5 was almost 10 times than that at pH 6.5. A total of 40 compounds were tentatively identified as chloro-substituted BPF and polyphenolic compounds by liquid chromatography quadrupole time-of-flight mass spectrometry operating in electrospray ionization mode (LC-ESI-Q-ToF), and 4 main byproducts were confirmed by ¹H and ¹³C nuclear magnetic resonance (NMR). Toxicity tests indicated that the estrogenic effects of chloro-substituted BPF decrease as the chlorine substitution increase. On the contrary, increasing numbers of chlorines on the phenolic rings of BPF enhanced the nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) activity. Tetra-chlorinated BPF had an approximately 6.9-fold higher activity than BPF.

Lower Serum Levels of Uric Acid in Uterine Fibroids and Fibrocystic Breast Disease Patients in Dongying City, China

BACKGROUND

Increasing serum levels of uric acid (SUA) after menopause in women brought up a hypothesis that estrogenic effect may protectively regulate SUA. Estrogenic effect is a major etiology of uterine fibroids and fibrocystic breast disease. The study aimed to explore SUA among patients suffering from these diseases to enhance the hypothesis.

METHODS

Overall, 1349 female participants were selected into three cases: Case I having uterine fibroids (n=568), Case II having fibrocycstic breast disease (n=608) and Case III having uterine fibroids combining with fibrocycstic breast disease (n=173); 4206 participants without these diseases were selected as controls. Based on health check-up data from 2011 to 2012, in Dongying Shengli Oilfield Central Hospital, a cross-sectional study was conducted to examine the difference in SUA between the case and control. We adjusted covariates by generalized linear regression mode.

RESULTS

From 19 to 44 yr, SUA of Case I to Case III were lower than controls by 8.46 umol/L (P=0.011), 5.88umol/L (P=0.014) and 9.39 umol/L (P=0.059), respectively. From 45-54 yr, no significant differences were between three cases and controls. In Case I and its control: from 54-59 yr, differences were not significant; from 60 to 72 yr, SUA in Case I was lower than the control by 32.02umol/L (P=0.003).

CONCLUSION

Participants of uterine fibroids and fibrocystic breast disease had a lower SUA except the stage of menopause, which indirectly supported that estrogenic effect, may protectively decrease SUA.

Coupling of In Vitro Bioassays with Planar Chromatography in Effect-Directed Analysis

Modern analytical test methods increasingly detect anthropogenic organic substances and their transformation products in water samples and in the environment. The presence of these compounds might pose a risk to the aquatic environment. To determine a possible (eco)toxicological risk, aquatic samples are tested using various bioassays, including sub-organismic assays such as the luminescent bacteria inhibition test, the acetylcholinesterase inhibition test, and the umu-test. The effect-directed analysis (EDA) combines physicochemical separation methods with biological (in vitro) tests. High-performance thin-layer chromatography (HPTLC) has proved to be particularly well suited for the separation of organic compounds and the subsequent analysis of effects by the application of the biotests directly on the surface of the HPTLC plate. The advantage of using HPTLC in comparison to high-performance liquid chromatography (HPLC) for EDA is that the solvent which is used as a mobile phase during chromatography is completely evaporated after the separation and therefore can no longer influence the applied bioassays.A prioritization during the complex identification process can be achieved when observed effects are associated with the separated zones in HPTLC. This increases the probability of identifying the substance responsible for an adverse effect from the multitude of organic trace substances in environmental samples. Furthermore, by comparing the pattern of biological effects of a separated sample, it is possible to track and assess changes in biological activity over time, over space, or in the course of a process, even without identifying the substance. HPTLC has already been coupled with various bioassays.Because HPTLC is a very flexible system, various detection techniques can be used and combined. In addition to the UV/Vis absorption and fluorescence measurements, TLC can also be coupled with a mass spectrometer (MS) for compound identification. In addition, detection of functional groups by means of derivatization reagents can support this identification. It is also possible to combine derivatization and HPLC-MS.Two case studies are used to illustrate the significance of HPTLC-EDA in investigating water quality: Study on a wastewater treatment plant Possible influence of an artificial turf surface on ground water.

Environmental concentration of nonylphenol alters the development of urogenital and visceral organs in avian model

Nonylphenol (NP) is an endocrine disruptor with harmful effects including feminization and carcinogenesis on various organisms. This substance is a degradation product of nonylphenol ethoxylates (NPEO) that is used in several industrial and agricultural processes. In this paper, we examined the assessment of NP exposure on chick embryo development, using a concentration consistent with the environmental concentrations of NP. With this aim, NP (between 0.1 and 50 μg/egg) was injected into the yolk of egg through a small needle hole in the shell. We report the effect of NP on chick reproductive system development although the effect we observed is lower than those observed by exposition to other endocrine disruptors. However, histological analysis highlighted a decrease of intraluminal seminiferous surface area in 64.12% of case (P=0.0086) and an heterogeneous organization of the renal tubules when 10 μg/egg were injected. Moreover, an impairment of liver development with an abnormal bile spillage was observed when higher concentration of NP was injected (50 μg/egg).

Vitellogenin as biomarker for estrogenicity in flounder Platichthys flesus in the field and exposed to 17α-ethinylestradiol via food and water in the laboratory

The ability of 17α-ethinylestradiol (EE2) to elevate vitellogenin levels were investigated in male flounder Platichthys flesus and vitellogenin concentrations in flounders from the Danish coastal environment were determined. Male flounders were exposed to 17α-ethinylestradiol (EE2) via food or water. Average vitellogenin concentrations in the control fish ranged between 25 and 100 ng mL(-)(1). Exposure to 5.1, 8.1 and 16.8 ng EE2 L(-)(1) in water and 500 and 5000 ng EE2 kg(-)(1) body weight (bw) every second day in the food increased the plasma vitellogenin concentration in a concentration and time dependent manner, whereas exposure to 2.7 ng EE2 L(-)(1) in water for 21 d and 5 and 50 ng EE2 kg(-)(1) bw for 12 days in the food did not. EE2 could be detected in liver and testes (but not in muscle) after exposure to 8.1 and 16.8 ng EE2 L(-)(1) in the water and 5000 ng EE2 kg(-)(1) bw in the food; the highest concentration was 6 ng g(-)(1) wet weight in liver. The majority of the male flounders collected from nine coastal Danish sites from 1999 to 2004 had vitellogenin concentrations below 100 ng mL(-)(1), and only at two sites moderate estrogenic inputs were indicated.

Glyphosate induces human breast cancer cells growth via estrogen receptors

Glyphosate is an active ingredient of the most widely used herbicide and it is believed to be less toxic than other pesticides. However, several recent studies showed its potential adverse health effects to humans as it may be an endocrine disruptor. This study focuses on the effects of pure glyphosate on estrogen receptors (ERs) mediated transcriptional activity and their expressions. Glyphosate exerted proliferative effects only in human hormone-dependent breast cancer, T47D cells, but not in hormone-independent breast cancer, MDA-MB231 cells, at 10⁻¹² to 10⁻⁶M in estrogen withdrawal condition. The proliferative concentrations of glyphosate that induced the activation of estrogen response element (ERE) transcription activity were 5-13 fold of control in T47D-KBluc cells and this activation was inhibited by an estrogen antagonist, ICI 182780, indicating that the estrogenic activity of glyphosate was mediated via ERs. Furthermore, glyphosate also altered both ERα and β expression. These results indicated that low and environmentally relevant concentrations of glyphosate possessed estrogenic activity. Glyphosate-based herbicides are widely used for soybean cultivation, and our results also found that there was an additive estrogenic effect between glyphosate and genistein, a phytoestrogen in soybeans. However, these additive effects of glyphosate contamination in soybeans need further animal study.