New screening methods for chemicals with hormonal activities using interaction of nuclear hormone receptor with coactivator

Bacterial degradation and reduction in the estrogen activity of 4-nonylphenol

Bacteria capable of degrading 4-nonylphenol (NP) were isolated and identified, and their ability to degrade NP was determined. The screening of microorganisms in river water and soil led to a collection of 23 strains of bacteria and five strains of fungi. Two strains of bacteria, identified as Pseudomonas sp. and Acidovorax sp., possessed great ability for degrading NP. The NP degradation rate of Pseudomonas sp. did not change with the NP concentration (50-100mg/L) . In contrast, the NP degradation rate of Acidovorax sp. increased with increasing NP concentration. Acidovorax sp. possessed the greatest NP degradation activity at 35°C. No NP degradation activity was observed for Pseudomonas sp. at temperatures higher than 30°C. Even when non-NP carbon sources such as glucose or sucrose were added, the NP degradation rates for both bacteria did not decrease. In addition, the estrogenic activity of NP decreased depending on the amount of NP residues determined by the yeast two-hybrid system.

Tools to evaluate estrogenic potency of dietary phytoestrogens:A consensus paper from the EU Thematic Network "Phytohealth" (QLKI-2002-2453)

Phytoestrogens are naturally occurring plantderived polyphenols with estrogenic potency. They are ubiquitous in diet and therefore, generally consumed. Among Europeans, the diet is rich in multiple putative phytoestrogens including flavonoids, tannins, stilbenoids, and lignans. These compounds have been suggested to provide beneficial effects on multiple menopause-related conditions as well as on development of hormone-dependent cancers, which has increased the interest in products and foods with high phytoestrogen content. However, phytoestrogens may as well have adverse estrogenicity related effects similar to any estrogen. Therefore, the assessment of estrogenic potency of dietary compounds is of critical importance. Due to the complex nature of estrogenicity, no single comprehensive test approach is available. Instead, several in vitro and in vivo assays are applied to evaluate estrogenic potency. In vitro estrogen receptor (ER) binding assays provide information on the ability of the compound to I) interact with ERs, II) bind to estrogen responsive element on promoter of the target gene as ligand-ER complex, and III) interact between the co-activator and ERs in ligand-dependent manner. In addition, transactivation assays in cells screen for ligand-induced ERmediated gene activation. Biochemical in vitro analysis can be used to test for possible effects on protein activities and E-screen assays to measure (anti)proliferative response in estrogen responsive cells. However, for assessment of estrogenicity in organs and tissues, in vivo approaches are essential. In females, the uterotrophic assay is applicable for testing ERa agonistic and antagonistic dietary compounds in immature or adult ovariectomized animals. In addition, mammary gland targeted estrogenicity can be detected as stimulated ductal elongation and altered formation of terminal end buds in immature or peripubertal animals. In males, Hershberger assay in peri-pubertal castrated rats can be used to detect (anti)androgenic/ (anti)estrogenic responses in accessory sex glands and other hormone regulated tissues. In addition to these short-term assays, sub-acute and chronic reproductive toxicity assays as well as two-generation studies can be applied for phytoestrogens to confirm their safety in long-term use. For reliable assessment of estrogenicity of dietary phytoestrogens in vivo, special emphasis should be focused on selection of the basal diet, route and doses of administration, and possible metabolic differences between the species used and humans. In conclusion, further development and standardization of the estrogenicity test methods are needed for better interpretation of both the potential benefits and risks of increasing consumption of phytoestrogens from diets and supplements.

Degradation of alkylphenols by white rot fungus Irpex lacteus and its manganese peroxidase

Alkylphenols are common endocrine disrupters that are produced from the degradation of widely used surfactants. Since they cause various harmful effects on aquatic life and in humans, they should be removed from the environments being contaminated. White rot fungus Irpex lacteus can completely degrade 100 mg/L of octylphenol, nonylphenol, and phenylphenol during 1 day of incubation in the complex YMG medium, which was the highest degrading capability among nine strains of white rot fungi tested. In the N-limited Kirk's basal salts medium, I. lacteus could degrade almost 100 % of 100 mg/L octylphenol and nonylphenol in 1 h, and exhibited a high activity of manganese peroxidase (MnP; 1,790 U/L). MnP of I. lacteus was purified by ion exchange chromatography, and this degraded 99 % of 50 mg/L octylphenol and removed 80 % of estrogenic activity in 2 hours. In addition, the purified MnP (10 U/mL) degraded over 90 % of 50 mg/L nonylphenol in 1 h.

Multiple in vitro bioassay approach in sediment toxicity evaluation: Masan Bay, Korea

Extracts of 21 sediment samples from Masan Bay, Korea, used in an earlier chemical measurement, were screened for their ability to induce estrogen, - and dioxin - like gene expression using the E-Assay (+), DR-CALUX assay, respectively, and to inhibit acetylcholinesterase (AChE) activity using an in vitro AChE assay. Biological impact in the industry-rich inner bay is higher than outer bay. DDTs (0.65), coplanar PCBs (0.77), HCHs (0.64), PAHs (0.61) and APs (0.53) with good correlation to E-assay (+) are seen as environmental estrogens. The highest induction of DR-CALUX response was seen again at station M12 and 15 which received sewage effluents. PCDD/DFs gave the highest correlation (0.75). Interestingly, the M12 station at the sewage treatment outlet showed the highest activity. Among the targeted chemicals APs (0.66), PCBs (0.64), PAHs (0.61) and DDT (0.49) correlated well with the AChE bioassay. Spearman rank correlation on analytical and biochemical results affirmed the 'hot spots' and point sources (e.g., sewage treatment and industrial outfall) and suspected toxicants. Significant correlations between organo chlorine pesticides, PCBs, dioxins and alkylphenols and their biological effects were observed.

Detection of retinoic acid receptor agonistic activity and identification of causative compounds in municipal wastewater treatment plants in Japan

Retinoic acid (RA) receptor (RAR) agonists are potential toxicants that can cause teratogenesis in vertebrates. To determine the occurrence of RAR agonists in municipal wastewater treatment plants (WWTPs), we examined the RARα agonistic activities of influent and effluent samples from several municipal WWTPs in Osaka, Japan, using a yeast two-hybrid assay. Significant RARα agonistic activity was detected in all the influent samples investigated, suggesting that municipal wastewater consistently contains RAR agonists. Fractionations using high-performance liquid chromatography, directed by the bioassay, found several bioactive peaks from influent samples. The RAR agonists, all-trans RA (atRA), 13-cis RA (13cRA), 4-oxo-atRA, and 4-oxo-13cRA, possibly arising from human urine, were identified by liquid chromatography ion trap time-of-flight mass spectrometry. Quantification of the identified compounds in municipal WWTPs confirmed that they were responsible for the majority of RARα agonistic activity in WWTP influents, and also revealed they were readily removed from wastewater by activated sludge treatment. Simultaneous measurement of the RARα agonistic activity revealed that although total activity typically declined concomitant with the reduction of the four identified compounds, it remained high after the decline of RAs and 4-oxo-RAs in one WWTP, suggesting the occurrence of unidentified RAR agonists during the activated sludge treatment.

Effective removal of endocrine-disrupting compounds by lignin peroxidase from the white-rot fungus Phanerochaete sordida YK-624

The removal of endocrine-disrupting compounds (EDCs) by lignin peroxidase from white-rot fungus Phanerochaete sordida YK-624 (YK-LiP1) was investigated. Five endocrine disruptors, p-t-octylphenol (OP), bisphenol A (BPA), estrone (E(1)), 17β-estradiol (E(2)), and ethinylestradiol (EE(2)) were eliminated by YK-LiP1 more effectively than lignin peroxidase from P. chrysosporium (Pc-LiP), and OP and BPA were disappeared almost completely in the reaction mixture containing YK-LiP1 after a 24-h treatment. Particularly, the removal of estrogenic activities of E(2) and EE(2), which show much higher estrogenic activities than other EDCs such as BPA and OP, were removed following 24-h treatment with YK-LiP1. Moreover, 5,5'-bis(1,1,3,3-tetramethylbutyl)-[1,1'-biphenyl]-2,2'-diol and 5,5'-bis-[1-(4-hydroxy-phenyl)-1-methyl-ethyl]-biphenyl-2,2'-diol were identified as the main metabolite from OP or BPA, respectively. These results suggest that YK-LiP1 is highly effective in removing of EDCs by the oxidative polymerization of these compounds.

The feasibility of using mosquitofish (Gambusia affinis) for detecting endocrine-disrupting chemicals in the freshwater environment

We evaluated the utility of gene-transcriptional responses in the liver of mosquitofish (Gambusia affinis), a species introduced to many countries and therefore widely available, for detecting endocrine-disrupting activity in water. Exposure to β-naphthoflavone, an aryl hydrocarbon receptor (AhR) agonist, significantly increased the transcript of the cytochrome P4501A gene (cyp1a), peaking at 24 h, in both sexes at concentrations of 10 µg/L or more. 17β-Estradiol (E(2) ) at 500 ng/L increased the number of males showing gene transcription of precursors of yolk protein, vitellogenin (Vtga, Vtgb, and Vtgc), at 24, 48, and 72 h. Exposure for 48 h to bisphenol A (BPA), an estrogen mimic, also increased vtg-positive males at 1 mg/L or more. Leachate from a Japanese stable-type landfill significantly increased vtg-positive males after 48 h exposure, and the in vitro activity of the leachate against the estrogen receptor (ER) was estimated as an E(2) equivalent of 240 ng/L by yeast transfected with the ER. Chemical analysis showed that major contributors to the ER activation were BPA and 4-tert-octylphenol. This leachate and drainage water from a control-type landfill had AhR activities, estimated by yeast with the AhR, but had no significant effect on cyp1a transcription. These results showed that mosquitofish are suitable for detecting in vivo AhR and ER effects, but are insensitive to E(2).

Screening for estrogenic and antiestrogenic activities of plants growing in Egypt and Thailand

Background:

There is a growing demand for the discovery of new phytoestrogens to be used as a safe and effective hormonal replacement therapy.

Materials and Methods:

The methanol extracts of 40 plants from the Egyptian and Thailand folk medicines were screened for their estrogen agonist and antagonist activities. The estrogenic and antiestrogenic effects of the tested extracts were carried out using the yeast two-hybrid assay system expressing ERα and ERβ. In addition, all the extracts were subjected to a naringinase treatment and retested for their estrogenic activity.

Results:

The methanol extracts of Derris reticulata and Dracaena lourieri showed the most potent estrogenic activity on both estrogen-receptor subtypes, while, the methanol extracts of Butea monosperma, Erythrina fusca, and Dalbergia candenatensis revealed significant estrogenic activity on ERβ only. Nigella sativa, Sophora japonica, Artabotrys harmandii, and Clitorea hanceana showed estrogenic effect only after naringinase treatment. The most potent antiestrogenic effect was revealed by Aframomum melegueta, Dalbergia candenatensis, Dracena loureiri, and Mansonia gagei.

In vitro assessment of retinoic acid and aryl hydrocarbon receptor activity of treated effluent from 39 wastewater-treatment plants in Victoria, Australia

This project involved the collection of final effluent samples from 39 wastewater-treatment plants (WWTPs) in Victoria, Australia, in late summer (late February to early March 2007). The 39 WWTPs included 15 lagoon-based plants and 24 with activated sludge-based processes. Samples were collected and subjected to measurement of retinoic acid receptor (RAR) and aryl hydrocarbon receptor (AhR) activity of the dissolved phase using yeast-based recombinant receptor-reporter gene bioassays. More than 90% of the effluents examined in this study elicited RAR activity (<0.5-198 ng/l a-t-RA equivalents [EQ]). All of the effluents had AhR activity (16-279 ng/l βNF EQ). Notwithstanding the paucity of comparative data, on the whole, the levels of RAR and AhR activity observed in this pilot survey of Victorian WWTP effluents were greater than those recently reported internationally. One assumption commonly made is that WWTP discharges will be diluted significantly in the receiving environment, further decreasing the potential risk of the discharges. Making this assumption may not be appropriate for some of Victoria's more ephemeral waterways or where effluent is discharged to an enclosed water body, such as a lake or terminal wetland. However, even where WWTP discharges represent all of the environmental flow in the warmer months, the observed RAR and AhR activity (as all-trans-retinoic acid (RA) and 2,3,7,8-tetrachloro-dibenzo-p-dioxin [TCDD] EQ, respectively) was still significantly lower than the concentrations of RA, and 2,3,7,8-TCCD known to cause developmental malformations in fish larvae after short-term exposure to these chemicals. Of perhaps greater concern, WWTP effluent can contain significant suspended solids (essentially biosolids), which may be a considerable sink for some hormonally active, hydrophobic compounds, and which may in turn increase the long-term exposure risk for aquatic fauna. Further studies of the nuclear and AhR activity of WWTP effluent suspended soilds are required to address this hypothesis.

A pilot study of the water quality of the Yarra River, Victoria, Australia, using in vitro techniques

A pilot study was initiated to provide the first information on the recombinant receptor-reporter gene bioassay (hormonal) activity of freshwaters in Victoria. The project involved the collection of water samples from six stations on the main stem of the Yarra River in and upstream of the city of Melbourne, Australia in April 2008 and April 2009. Samples were prepared for measurement of sample toxicity using a modified photobacterium test, genotoxicity using a high-throughput luminescent umu test method, and human and medaka estrogen receptor (hERα and medERα), retinoic acid receptor (RAR), aryl hydrocarbon receptor (AhR) and thyroid receptor (TR) assay activity using the relevant yeast-based bioassays. Most samples were only weakly or moderately toxic, with no relationship observed to location along the river. The data for 2008 suggests that at that time the Yarra River samples contained few compounds that were, in and of themselves, genotoxic. No estrogenic or thyroid, and <1 ng/L retinoic acid receptor activity was observed. AhR activity increased with progressed downstream. AhR activity was higher in April 2009 than at the same time in 2008, perhaps as a result of extensive bush fires in the catchment in the months immediately prior to sampling. About 24% of the total AhR activity observed was associated with suspended solids.

A comparison of recombinant receptor-reporter gene bioassays and a total estrogen enzyme linked immunosorbent assay for the rapid screening of estrogenic activity in natural and waste waters

In this study, we compared the performance as screening tools of two yeast-based recombinant receptor-reporter gene bioassays with a commercial ELISA kit for measurement of total estrogens. For WWTP effluents there was a very good correlation between the measured total estrogen concentrations (ELISA) and estrogenic activity by the hERα bioassay (r(2)=0.93), but not for the medERα bioassay (r(2)=0.50). For freshwater samples, the correlations between bioassay response and ELISA ES measurements were very good (r(2)>0.95). There was no correlation between bioassay response and ELISA ES measurements for estuarine samples.

Effects of 17β-estradiol and bisphenol A on the formation of reproductive organs in planarians

Planarians have a remarkable capacity for regeneration after ablation, and they reproduce asexually by fission. However, some planarians can also reproduce and maintain their sexual organs. During the regenerative process, their existing sexual organs degenerate and new ones develop. However, little is known about hormonal regulation during the development of reproductive organs in planarians. In this study, we investigated the effects of 17β-estradiol (a steroid) and bisphenol A (an endocrine disrupter) on the formation of sexual organs in the hermaphroditic planarian Dugesia ryukyuensis. Under control conditions, all worm tissues regenerated into sexual planarians with sexual organs within 4 weeks after ablation. However, in the presence of bisphenol A or 17β-estradiol, although they apparently regenerated into sexual planarians, the yolk glands, which are one of the female sexual organs, failed to regenerate even 7 weeks after ablation. These data suggest that planarians have a steroid hormone system, which plays a key role in the formation and maturation of sexual organs.

Estrogenic effects of leachates from industrial waste landfills measured by a recombinant yeast assay and transcriptional analysis in Japanese medaka

In Japan, the leachates from 'stable type' landfills for industrial wastes are not controlled, and this has given rise to concerns about the possible pollution of surrounding environmental waters, especially by endocrine disrupting chemicals leaching from plastic and rubber wastes. To accurately assess the estrogenic potential of the landfill leachates by both in vitro and in vivo approaches, we confirmed gene-transcriptional responses in recombinant yeast cells and in Japanese medaka fish to estrogenic compounds, and applied these transcription assays to leachate samples. The yeast carrying the estrogen receptor (ER) of medaka and an ER-mediated response pathway responded to both the natural estrogen, 17β-estradiol (E2), and an industrial compound, bisphenol A (BPA), and the effective concentration of BPA was about 2.0×10(3) times that of E2. Transcripts of all genes coding for precursors of yolk protein, vitellogenin (vtg1 and vtg2), and precursors of egg envelope subunit proteins, choriogenins (chgh and chgl), increased in a concentration dependent manner in the livers of male medaka exposed to BPA or E2, and, except for chgh, reached peaks at exposure times of 48h. Although many fish in control groups did not have vtg transcripts, the incidence of vtg transcriptions also increased in a concentration dependent manner with exposure. The minimum effective concentrations of BPA at 48h were 0.5mg/L for chgh and vtg2, 2mg/L for vtg1 and 4mg/L for chgl, while those of E2 were 10ng/L for chgh and chgl and 30ng/L for vtg1 and vtg2. All leachates sampled at 3 landfill sites exerted in vitro estrogenic action. The E2 equivalent of the most potent leachate was 375ng/L for the yeast ER assay. This leachate sample significantly increased the transcripts of chgh, vtg1 and vtg2, but not chgl, in the medaka. In addition, chemical analysis showed that bisphenol A, 4-tert-octylphenol and 4-nonylphenol were the main contributors to the estrogenicity of the leachates. This study indicated that this type of landfill may adversely affect the reproductive functions of fish living in the surrounding area by leakage of industrial estrogenic compounds.

Screening of agonistic activities against four nuclear receptors in wastewater treatment plants in Japan using a yeast two-hybrid assay

To assess the potential endocrine disruptive effects through multiple nuclear receptors (NRs), especially non-steroidal NRs, in municipal wastewater, we examined the agonistic activities on four NRs (estrogen receptor alpha, thyroid hormone receptor alpha, retinoic acid receptor alpha and retinoid X receptor alpha) of untreated and treated wastewater from municipal wastewater treatment plants (WWTPs) in Japan using a yeast two-hybrid assay. Investigation of the influent and effluent of seven WWTPs revealed that agonistic activities against steroidal and non-steroidal NRs were always detected in the influents and partially remained in the effluents. Further investigation of four WWTPs employing conventional activated sludge, pseudo-anoxic-oxic, anoxic-oxic and anaerobic-anoxic-oxic processes revealed that the ability to reduce the agonistic activity against each of the four NRs varies depending on the treatment process. These results indicated that municipal wastewater in Japan commonly contains endocrine disrupting chemicals that exert agonistic activities on steroidal and non-steroidal NRs, and that some of these chemicals are released into the natural aquatic environment. Although the results obtained in yeast assays suggested that measured levels of non-steroidal NR agonists in the effluent of WWTPs were not likely to cause any biological effect, further study is required to assess their possible risks in detail.

Determination and occurrence of retinoic acids and their 4-oxo metabolites in Liaodong Bay, China, and its adjacent rivers

Retinoic acids (RAs) and their metabolites play an important role in abnormal morphological development and are speculated to be a possible cause for the increased rates of deformities in wild frog populations. In the current study, a method using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry was developed for simultaneously analyzing all-trans-RA (at-RA), 13-cis-RA (13c-RA), 9-cis-RA (9c-RA), and their 4-oxo metabolites, all-trans-4-oxo-RA (at-4-oxo-RA), 13-cis-4-oxo-RA (13c-4-oxo-RA), and 9-cis-4-oxo-RA (9c-4-oxo-RA) in wastewaters and surface waters. Method detection limits were matrix dependent, ranging from 0.02 to 0.37 ng/L. The method was used to investigate the occurrence of RAs and 4-oxo-RAs in Liaodong Bay and its adjacent rivers. Of these six retinoids, at-RA, 13c-RA, at-4-oxo-RA, and 13c-4-oxo-RA were detected in river waters at detection frequencies of 100%, 92%, 48.6%, and 21.6%, and concentrations of 0.05 to 1.23 ng/L, less than 0.03 to 0.41 ng/L, less than 0.02 to 1.00 ng/L, and less than 0.06 to 0.81 ng/L, respectively. Retinoic acids were detected for the first time in the aquatic environment and were found to be more persistent than 4-oxo-RAs. The hazard quotient for mortality of frog embryos caused by induction by retinoids detected in the current study was then estimated, and the value was calculated to be 0.09. No retinoid was detected in seawaters.

Identification of a naturally occurring rexinoid, honokiol, that activates the retinoid X receptor

Screening of a total of 86 crude drugs for retinoid X receptor (RXR) ligands demonstrated that the methanol extract of the bark of Magnolia obovata markedly activated the transcriptional activity of RXRalpha in luciferase reporter assays. Thereafter, honokiol (1) was isolated as a constituent able to activate RXR selectively as a natural rexinoid, but not RARalpha. The activity of 1 was more potent than those of phytanic acid and docosahexaenoic acid, both of which are known to be natural RXR agonists. Honokiol (1) is capable of activating a RXR/LXR heterodimer, resulting in the induction of ATP-binding cassette transporter A1 mRNA and protein expression in RAW264.7 cells, as well as an increase in [(3)H]cholesterol efflux from peritoneal macrophages. These effects of 1 were enhanced synergistically in the presence of an LXR agonist, 22(R)-hydroxycholesterol. The results obtained demonstrate that 1, a newly identified natural rexinoid, regulates the functions of RXR/LXR heterodimer and abrogates foam cell formation by the induction of ABCA1 via activation of the RXR/LXR heterodimer.

In vitro and in vivo estrogenic effects of 17alpha-estradiol in medaka (Oryzias latipes)

17alpha-Estradiol (17alpha-E2), the stereoisomer of 17beta-estradiol (17beta-E2), is considered a weak estrogen in mammals. However, little is known about its estrogenic potency in teleost fish, even though 17alpha-E2 has been frequently detected in aquatic environment. To investigate the estrogenic activity of 17alpha-E2, an in vitro assay based on the ligand-dependent interaction between medaka estrogen receptor alpha (med-ERalpha) and coactivator was conducted. Japanese medaka (Oryziaslatipes) were exposed to 1, 10, 100, 1000 and 10000ng L(-1) 17alpha-E2 (actual concentrations of 1.91, 12.81, 96.24, 1045.15, and 9320.81ng L(-1), respectively) for 3 weeks, and expression for vitellogenins (VTG-I), Choriogenin H (CHG-H) and estrogen receptor alpha (ERalpha) mRNA in the livers was analyzed by quantitative real-time RT-PCR (Q-RT-PCR). The in vitro study showed that the EC(50) of 17alpha-E2 was 114.10nM, which was 30 times less potent than that of 17beta-E2 (3.80nM). Dose-dependent induction of gene expression of VTG-I, CHG-H and ERalpha were observed. The benchmark dose (BMD) values for VTG-I, CHG-H and ERalpha were 44.16ng L(-1), 15.25ng L(-1) and 66.03ng L(-1), which were about 11-, 17- and 14-times less potent than that of 17beta-E2, respectively. Comparing this study with those reported previously in mammals, it is suggested that fish species may be more susceptive to 17alpha-E2 than mammals.

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 alpha (hERalpha). 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 17beta-estradiol (E(2)) equivalent concentration. By using authentic standards, it was found that MMP possessed weak estrogenic activity; its activity was evaluated as 1.7x10(-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.

Contamination with retinoic acid receptor agonists in two rivers in the Kinki region of Japan

This study was conducted to investigate the agonistic activity against human retinoic acid receptor (RAR) alpha in the Lake Biwa-Yodo River and the Ina River in the Kinki region of Japan. To accomplish this, a yeast two-hybrid assay was used to elucidate the spatial and temporal variations and potential sources of RARalpha agonist contamination in the river basins. RARalpha agonistic activity was commonly detected in the surface water samples collected along two rivers at different periods, with maximum all-trans retinoic acid (atRA) equivalents of 47.6 ng-atRA/L and 23.5 ng-atRA/L being observed in Lake Biwa-Yodo River and Ina River, respectively. The results indicated that RARalpha agonists are always present and widespread in the rivers. Comparative investigation of RARalpha and estrogen receptor alpha agonistic activities at 20 stations along each river revealed that the spatial variation pattern of RARalpha agonist contamination was entirely different from that of the estrogenic compound contamination. This suggests that the effluent from municipal wastewater treatment plants, a primary source of estrogenic compounds, seemed not to be the cause of RARalpha agonist contamination in the rivers. Fractionation using high performance liquid chromatography (HPLC) directed by the bioassay found two bioactive fractions from river water samples, suggesting the presence of at least two RARalpha agonists in the rivers. Although a trial conducted to identify RARalpha agonists in the major bioactive fraction was not completed as part of this study, comparison of retention times in HPLC analysis and quantification with liquid chromatography-mass spectrometry analysis revealed that the major causative contaminants responsible for the RARalpha agonistic activity were not RAs (natural RAR ligands) and 4-oxo-RAs, while 4-oxo-RAs were identified as the major RAR agonists in sewage in Beijing, China. These findings suggest that there are unknown RARalpha agonists with high activity in the rivers.

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 ERbeta only.

[Combined estrogenic activity of soybean extract used in a dietary supplement and ethinyl estradiol]

We examined the combined estrogenic activity of soybean extract used in a dietary supplement and ethinyl estradiol (EE) contained in an oral contraceptive. Olive oil (control), soybean extract (0.0036 or 0.36 g/kg corresponding to doses of total isoflavone of 0.83 or 83 mg/kg respectively), EE (1 or 10 microg/kg), and soybean extract+EE were administered to ovariectomized CD-1 mice by oral gavage for 4 consecutive days. Soybean extract (0.0036 or 0.36 g/kg) and EE (1 microg/kg) did not increase the relative uterine weight. The relative uterine weight of the soybean extract (0.0036 or 0.36 g/kg)+EE (10 microg/kg) group was significantly higher than that of the control. The relative uterine weight of the soybean extract (0.36 g/kg)+EE (10 microg/kg) group was also significantly higher than that of the EE (10 microg/kg) group. Soybean extract showed estrogenic activity for human estrogen receptor (hER)-alpha and -beta. Coadministration of EE with soybean extract increased the estrogenic activity for hER-alpha and -beta.

Differential binding with ERalpha and ERbeta of the phytoestrogen-rich plant Pueraria mirifica

Variations in the estrogenic activity of the phytoestrogen-rich plant, Pueraria mirifica, were determined with yeast estrogen screen (YES) consisting of human estrogen receptors (hER) hERalpha and hERbeta and human transcriptional intermediary factor 2 (hTIF2) or human steroid receptor coactivator 1 (hSRC1), respectively, together with the beta-galactosidase expression cassette. Relative estrogenic potency was expressed by determining the beta-galactosidase activity (EC(50)) of the tuber extracts in relation to 17beta-estradiol. Twenty-four and 22 of the plant tuber ethanolic extracts interacted with hERalpha and hERbeta, respectively, with a higher relative estrogenic potency with hERbeta than with hERalpha. Antiestrogenic activity of the plant extracts was also determined by incubation of plant extracts with 17beta-estradiol prior to YES assay. The plant extracts tested exhibited antiestrogenic activity. Both the estrogenic and the antiestrogenic activity of the tuber extracts were metabolically activated with the rat liver S9-fraction prior to the assay indicating the positive influence of liver enzymes. Correlation analysis between estrogenic potency and the five major isoflavonoid contents within the previously HPLC-analyzed tuberous samples namely puerarin, daidzin, genistin, daidzein, and genistein revealed a negative result.

Development and validation of chemical and biological analyses to determine the antiestrogenic potency of resin acids in paper mill effluents

This study combined chemical analysis and bioassays of paper mill effluents and their components in order to determine their antiestrogenic activity. The bioassay comprised a yeast two-hybrid assay incorporating the estrogen receptor alpha (hERalpha) and an hERalpha competitive enzyme-linked immunosorbent assay (ELISA). Samples were fractionated by solid phase extraction (SPE) with a C18 disk and a Florisil cartridge to obtain four fractions. The final fraction, eluted with methanol from the Florisil cartridge after pre-extraction by the C18 disk, was the most active in the two-hybrid assay, and its antiestrogenic potency, expressed as the equivalent concentration to 4-hydroxytamoxifen (OHT), was 277 nM. Seven resin acids had antiestrogenic activity in the active fraction as determined by gas chromatography/mass spectrometry (GC/MS), and their concentration levels ranged from 0.11 to 12 microg/L. All the resin acids exhibited greater activity than OHT; their activity relative to OHT ranged from 2.8- to 4.0-fold in the yeast two-hybrid assay. Based on the chemical analysis data and relative potency of resin acids from the yeast two-hybrid assay, the contribution ratio of resin acids accounted for 72% of the observed antiestrogenic activity of the extract. Furthermore, no resin acid showed any affinity for the estrogen receptor in the ELISA. This study showed that analysis combining the SPE method and the yeast two-hybrid assay is likely to be effective for the comprehensive monitoring of resin acids in paper mill industrial discharge areas.

Identification of retinoic acid receptor agonists in sewage treatment plants

Retinoic acid receptor (RAR) agonists are speculated to be one possible cause for the widely observed frog deformities in North America, although little is known about the specific RAR agonists in aquatic environments. We identified the specific RAR egonists in sewage treatment plants (STPs) and receiving rivers using an RAR yeast two-hybrid bioassay. Water samples were extracted by solid-phase extract cartridges, which were successively eluted by hexane, ethyl acetate, and methanol for bioassay. Among the three fractions, the ethyl acetate fraction showed the highest RAR agonistic activities. The bioassay-derived activity, expressed as all-trans-retinoic acid (all-transRA) equivalents (ATRA-EQ) were 10.9 +/- 2.2 and 1.7 +/- 1.0 ng/L in the STP influents and effluents, respectively, while the ATRA-EQs were as high as 7.1 and 8.3 ng/L in the two rivers receiving STP effluents. Following a two-step fractionation using high-performance liquid chromatography and ultra-performance liquid chromatography (UPLC) directed by the bioassay, two bioactive fractions were obtained from Gaobeidian STP influent and all-trans-4-oxo-RA (4.7-10.4 ng/L in influents, < 0.2-0.9 ng/L in effluents) and 13-cis-4-oxo-RA (2.3-7.1 ng/L in influents, < 0.4-1.1 ng/L in effluents) were identified in these fractions with UPLC-MS/MS. The EC50 for all-trans-4-oxo-RA or 13-cis-4-oxo-RA relative to that of all-trans-RA in exhibiting RARalpha agonistic activity was calculated to be 3.87 and 0.46, respectively.

Effect of chlorination on the estrogenic/antiestrogenic activities of biologically treated wastewater

Chlorination is widely used in wastewater reclamation, however harmful disinfection byproducts (DBPs) may be formed during disinfection. These DBPs are considered as a potential and important source of endocrine-disruption. In this study, the effects of chlorination on estrogenic and antiestrogenic activities in biologically treated wastewater were evaluated by yeast two-hybrid assay. For the first time, chlorination was found to increase the antiestrogenic activity of wastewater notably and decrease the estrogenic activity. By fractionating dissolved organic matter (DOM) in wastewater into different fractions, it was found that the polar compounds (PC) fraction of DOM was the key fraction involved in increasing antiestrogenic activity during chlorination of wastewater. Furthermore, fluorescence spectroscopy analysis on different fractions of soluble organic compounds in wastewater suggested that the PC fraction contained most of the aromatic amino acids and humic/fulvic acid, which were then demonstrated as the precursors of antiestrogenic DBPs through chlorination experiments of tryptophan, humic acid, and tannic acid.

Detection of agonistic activities against five human nuclear receptors in river environments of Japan using a yeast two-hybrid assay

A total of 16 water samples from four rivers in Japan were examined for their agonistic activities against five human nuclear receptors (estrogen receptor [ER] alpha, thyroid hormone receptor alpha, retinoic acid receptor [RAR] alpha, retinoid X receptor alpha, and vitamin D receptor) by using a yeast two-hybrid assay. The results suggest that the river environment is contaminated with endocrine disrupting chemicals (EDCs) that can interact with a variety of nuclear receptors and that contamination with those that have RAR agonistic activity may be more serious than contamination with well-known EDCs that act as ER agonists.

Evaluation of wastewater reclamation technologies based on in vitro and in vivo bioassays

When municipal secondary effluent is used as the main supplementation water source for surface water bodies, its potential adverse ecological effects should not be neglected. The objective of this work was to investigate the effectiveness of several technologies, i.e. combination of coagulation and sand filtration (CSF), ultraviolet (UV) irradiation, chlorination, ozonation, ultrafiltration (UF) and reverse osmosis filtration (RO), on the removal of acute ecotoxicity, genotoxicity and retinoic acid receptor (RAR) agonist activity from the municipal secondary effluent. The effects of treated effluents on the development of Japanese medaka (Oryzias latipes) embryos were also evaluated. The secondary effluent exhibited a mutagenic effect on Salmonella typhimurium strain TA 1535/pSK1002, acute invertebrate toxicity to Daphnia magna, and weak RAR alpha activity. RO and ozonation demonstrated remarkable removals of the genotoxic effect, acute toxicity and RAR activity from secondary effluent, while chlorination could elevate both genotoxicity and acute toxicity. CSF, UV, UF, chlorination as well as RO could decrease the 4-day mortality of medaka embryos and accordingly increase the hatching success rate, comparing with the secondary effluent. Ozonation at 4 mg/l and higher doses, however, elicited significantly higher 4-day mortality, leading to the reduction of the hatching success rate.

Estrogenic activity of diarylheptanoids from Curcuma comosa Roxb. Requires metabolic activation

Curcuma comosa Roxb. has traditionally been used as a dietary supplement for health promotion in peri- and postmenopausal women in Thailand. We investigated the estrogenic activity of 7 naturally occurring diarylheptanoids from the extracts of C. comosa both in vitro and in vivo. A yeast recombinant system containing human estrogen receptor alpha, coactivator TIF2 and a beta-galactosidase reporter gene was used to determine estrogenic activity of diarylheptanoids metabolically activated with rat liver S9-fraction prior to the assay. The most potent compound was (3R)-1,7-diphenyl-(4E,6E)-4,6-heptadien-3-ol, with a relative potency of 4% compared to 17beta-estradiol. The metabolic activation of diarylheptanoids markedly enhanced their efficiency. The chemical structure required for estrogenic activity of diarylheptanoids was the presence of a keto group at C3 and absence of hydroxyl moiety in ring B. Only diarylheptanoids showing full estrogenic efficiency in vitro were able to elicit uterotrophic activity of in immature ovariectomized rat. This is the first evidence for in vivo estrogenic activity of diarylheptanoids from C. comosa. This novel class of natural phytoestrogens has the potential to be developed for use as dietary supplement in the treatment of menopausal symptoms.

Suppression of estrogenic activity of 17-beta-estradiol by beta-cyclodextrin

The suppressive effects of cyclodextrins (CDs) on the strong estrogenic activity of 17beta-estradiol (E2) in water environments were investigated in this study. Cyclodextrins are doughnut-shaped molecules that possess a hydrophobic cavity and a hydrophilic exterior. The cavity can incorporate nonpolar molecules as guests to form inclusion complexes. beta-CD and 2-hydroxypropyl-beta-CD (HP-beta-CD) were the most successful in forming a complex with E2 and improving its low aqueous solubility. The E2/CDs complexes bound to the estrogen receptor in a cell-free system as determined by ELISA and suppressed the hormone activities as measured by a yeast two-hybrid assay. These results indicate that hydrophobic E2 is easily transported through the lipid zone of the plasma membrane into the target cell and can bind to the nuclear receptor. However, the hydrophilic E2/beta-CD and E2/HP-beta-CD complexes do not penetrate the membrane. Therefore, these CDs are able to suppress the hormone activity of E2 through complex formation.

Electrochemical characterization of enzymatic activity of yeast cells entrapped in a poly(dimethylsiloxane) microwell on the basis of limited diffusion system

A highly sensitive and quantitative analysis was performed using a poly(dimethylsiloxane) (PDMS) microwell array in a scanning electrochemical microscopy setup. A microelectrode with a relatively large seal radius was used to cover the top of the cylindrical PDMS microwell (96 pL). The voltammogram for 4 mM ferrocyanide resulted in a charge value of 38 nC, suggesting that almost 100% of the reductant in the microwell was converted to the oxidation current. When genetically modified yeast cells were entrapped in the microwell, the accumulation of p-aminophenol (PAP) produced by expressing beta-galactosidase (betaGAL) was successfully observed.

Estrogenic effects of a Kampo formula, Tokishakuyakusan, in parous ovariectomized rats

Female hormone-dependent cancers and other diseases pose a serious health threat for women, and low-risk medicines against such cancers have not yet been discovered. The present study examines the effects of the traditional Chinese herbal mixture, Tokishakuyakusan (TS) and 17beta-estradiol on the uterus of parous ovariectomized rats. Uterine atrophy that causes a reduction in uterine tissue and the uterine cavity area, was induced by ovariectomy, and slightly recovered by the daily oral administration of TS for two weeks (1000 mg/kg body weight). TS restored the decreased plasma estradiol concentration due to ovariectomy. However the yeast two-hybrid assay showed that TS did not bind estrogen receptors alpha and beta and immunohistochemical staining revealed that 17beta-estradiol stimulated the protein expression of estrogen receptor alpha, progesterone receptor, c-fos and c-jun in the uterus, whereas TS did not. These results suggest that TS might be useful for treating menopausal syndromes among women, as well as for patients when hormone replacement therapy (HRT) with estrogen is contraindicated.

Ligand structure-dependent activation of estrogen receptor alpha/Sp by estrogens and xenoestrogens

This study investigated the effects of E2, diethylstilbestrol (DES), antiestrogens, the phytoestrogen resveratrol, and the xenoestrogens octylphenol (OP), nonylphenol (NP), endosulfan, kepone, 2,3,4,5-tetrachlorobiphenyl-4-ol (HO-PCB-Cl(4)), bisphenol-A (BPA), and 2,2-bis-(p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE) on induction of luciferase activity in breast cancer cells transfected with a construct (pSp1(3)) containing three tandem GC-rich Sp binding sites linked to luciferase and wild-type or variant ERalpha. The results showed that induction of luciferase activity was highly structure-dependent in both MCF-7 and MDA-MB-231 cells. Moreover, RNA interference assays using small inhibitory RNAs for Sp1, Sp3 and Sp4 also demonstrated structure-dependent differences in activation of ERalpha/Sp1, ERalpha/Sp3 and ERalpha/Sp4. These results demonstrate for the first time that various structural classes of ER ligands differentially activate wild-type and variant ERalpha/Sp-dependent transactivation, selectively use different Sp proteins, and exhibit selective ER modulator (SERM)-like activity.