Home About us Contact
|
Home About us Contact | ||
|
|
||
Natural Estrogens (natural + estrogens)
Selected AbstractsEvaluation of estrogenic activity of phthalate esters by gene expression profiling using a focused microarray (estrarray®),ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2008Meher Parveen Abstract Phthalates are used industrially as plasticizers and are known to contaminate natural environments, mostly as di-ester or mono-ester complexes. Because they are structurally similar to natural estrogens, they could act as endocrine disruptors. Here, we used a DNA microarray containing estrogen responsive genes (EstrArray®) to examine gene expression profiles in MCF-7 cells treated with 10 ,M butylbenzyl phthalate (BBP), dibutyl phthalate (DBP), diethyl phthalate (DEP), and diisopropyl phthalate (DIP) along with the natural estrogen 17,-estradiol ([E2], 10 nM). The profiles for phthalate esters and E2 were examined by correlation analysis using correlation coefficients (r -values) and cluster analysis. We found that BBP showed the highest correlation with E2 (r = 0.85), and DEP and DIP showed moderate r -values (r = 0.52 and r = 0.49, respectively). Dibutyl phthalate exhibited the lowest (but still significant) correlation with E2 (r = 0.36). Furthermore, among the pairs of chemicals, DEP-DIP and DIP-DBP showed very high correlations (r = 0.90 and r = 0.80, respectively), and the other pairs showed moderate relationships, which reflected how structurally close they are to each other. The analysis of six functional groups of genes (enzymes, signaling, proliferation, transcription, transport, and others) indicated that the genes belonging to the enzyme, transcription, and other functional groups showed common responses to phthalate esters and E2. Although the effect of BBP was similar to that of E2, the other phthalate esters showed different types of effects. These results indicate that the structure of estrogenic chemicals is strongly related to their estrogenic activity and can be evaluated by appropriate grouping of the responsive genes by focused microarray analysis. [source] Mechanism of metabolic activation and DNA adduct formation by the human carcinogen diethylstilbestrol: The defining link to natural estrogensINTERNATIONAL JOURNAL OF CANCER, Issue 6 2009Muhammad Saeed Abstract Diethylstilbestrol (DES) is a human carcinogen, based on sufficient epidemiological evidence. DES is mainly metabolized to its catechol, 3,-hydroxyDES (3,-OH-DES), which can further oxidize to DES-3,,4,-quinone (DES-3,,4,-Q). Similarly to estradiol-3,4-quinone, the reaction of DES-3,,4,-Q with DNA would form the depurinating 3,-OH-DES-6,-N3Ade and 3,-OH-DES-6,-N7Gua adducts. To prove this hypothesis, synthesis of DES-3,,4,-Q by oxidation of 3,-OH-DES with Ag2O was tried; this failed due to instantaneous formation of a spiro -quinone. Oxidation of 3,-OH-DES by lactoperoxidase or tyrosinase in the presence of DNA led to the formation of 3,-OH-DES-6,-N3Ade and 3,-OH-DES-6,-N7Gua adducts. These adducts were tentatively identified by LC-MS/MS as 3,-OH-DES-6,-N3Ade, m/z = 418 [M+H]+, and 3,-OH-DES-6,-N7Gua, m/z = 434 [M+H]+. Demonstration of their structures derived from their oxidation by MnO2 to the DES quinone adducts and subsequent tautomerization to the dienestrol (DIES) catechol adducts, which are identical to the standard 3,-OH-DIES-6,-N3Ade, m/z = 416 [M+H]+, and 3,-OH-DIES-6,-N7Gua, m/z = 432 [M+H]+, adducts. The reaction of DIES-3,,4,-Q or lactoperoxidase-activated 3,-OH-DIES with DNA did not produce any depurinating adducts, due to the dienic chain being perpendicular to the phenyl planes, which impedes the intercalation of DIES into the DNA. Enzymic oxidation of 3,-OH-DES suggests that the catechol of DES intercalates into DNA and is then oxidized to its quinone to yield N3Ade and N7Gua adducts. These results suggest that the common denominator of tumor initiation by the synthetic estrogen DES and the natural estrogen estradiol is formation of their catechol quinones, which react with DNA to afford the depurinating N3Ade and N7Gua adducts. © 2008 Wiley-Liss, Inc. [source] Molecularly imprinted polymer for selective extraction of endocrine disrupters nonylphenol and its ethoxylated derivates from environmental solidsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2008Laura Núñez Abstract Nonylphenol isomers (NP), linear nonylphenol (4-n-NP) and NP short chain ethoxylated derivates (NPEO1 and NPEO2) are degradation products of nonylphenol polyethoxylates, a worldwide used group of surfactants. All of them are considered endocrine disrupters due to their ability to mimic natural estrogens. In this paper, the preparation and evaluation of several 4-n-NP molecularly imprinted polymers (MIPs) for the selective extraction and clean-up of 4-n-NP, NP, NPEO1 and NPEO2 from complex environmental solid samples is described. Among the different combinations tested, a methacrylic acid-based imprinted polymer prepared in toluene provided the better performance for molecularly imprinted SPE (MISPE). Under optimum MISPE conditions, the polymer was able to selectively retain not only linear NP but also the endocrine disruptors NPEO1, NPEO2 and NP with recoveries ranging from 60 to 100%, depending upon the analyte. The developed MISPE procedure was successfully used for the determination of 4-n-NP, NP, NPEO1 and NPEO2 in sediments and sludge samples at concentration levels according to data reported in the literature for incurred samples. Finally, various sludge samples collected at five different sewage treatment plants from Madrid and commercial sludge for agriculture purposes were analysed. The measured concentrations of the different compounds varied from 3.7 to 107.5 mg/kg depending upon the analyte and the sample. [source] Validation of a quantitative assay using GC/MS for trace determination of free and conjugated estrogens in environmental water samplesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 1-2 2003Asmaa Mouatassim-Souali Abstract It has been shown that sewage effluent can discharge human hormones and pharmaceuticals, particularly estrogens and synthetic chemicals, which are able to disrupt animal and human endocrine systems into surface waters. Since many surface waters receive sewage effluent and are subsequently used to produce drinking water, it is of principal interest to assess their contamination level and thereby their possible public health and environmental impact. To date, no data concerning the occurrence of estrogens present in the French aquatic environment are available. We therefore developed and validated an analytical procedure, which allows simultaneous quantitative determination of three natural estrogens, 17,-estradiol, estriol, and estrone and one of the synthetic estrogens most widely used in contraception, ethinylestradiol, in water. Water samples are extracted using solid-phase extraction (SPE) and then separated by gas-chromatography coupled with mass spectrometric detection. Under our conditions, detection limits of estrogens reached the pg range of injected sample, i. e. less than 0.1 ng L,1. Conjugated estrogens were also investigated using the same procedure as described above but with a enzymatic hydrolysis preliminary step before extraction. The analysis of samples collected from four wastewater treatment plants and from surface water showed significant concentrations of estrogens ranging from 2 to 18 ng L,1 and from 0.5 to 3 ng L,1, respectively. Furthermore, no estrogen conjugated forms were detected in the water samples. [source] Determination of non-steroidal estrogens in breast milk, plasma, urine and hair by gas chromatography/mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 24 2002Man Ho Choi It is suspected that all the natural estrogens occurring in the human body, as well as dietary and synthetic estrogens, diversely affect the endocrine system depending on their exposure patterns. More rapid, reliable and accurate measurements of these compounds in various biological matrices are thus becoming an important task. After solid-phase extraction using an Oasis HLB extraction cartridge, the estrogen concentrates were derivatized with a mixture of N -methyl- N -trifluorotrimethylsilylacetamide/ammonium iodide/dithioerythritol (1000:4:5, v/w/w) for analysis by gas chromatography/mass spectrometry in the selected ion-monitoring (SIM) mode. The qualitative identification of estrogens detected in SIM mode was further confirmed by tandem mass spectrometry using low-energy collision-induced dissociation (CID) mode. The method for the assay of the 20 estrogens was linear over the ranges of 1,1000,µg/L for biological fluids and 1,200,µg/kg for hair with high correlation coefficient (>0.99). The limits of quantitation (LOQ) ranged from 1.0,10,µg/L (or,µg/kg) and the limit of detection ranged from 0.2,3,µg/L (or,µg/kg). The average precision (% CV) and accuracy (% bias) of the method determined at the LOQ, low, and medium concentrations were in the ranges 2.6,9.2 and ,4.1,7.7, respectively. The average extraction recovery of the estrogens from plasma and hair at the three concentration levels varied in the ranges 77,103% (1.9,14.3% CV) and 73,104% (3.1,14%), respectively. The distribution patterns of the estrogens were characteristic of each biosample. Five estrogens in the range 1.5,44.9,µg/L were measured in breast milk, 8 estrogens in the range 3.5,322,µg/L in plasma, 12 estrogens at 1.2,442,µg/L in urine, and biochanin-A at 13.2,39.1,µg/kg in hair. Because of its high sensitivity, good precision and specificity, the present method was found suitable for the trace analysis of dietary and synthetic estrogens in complex biosamples such as breast milk, plasma, urine and hair. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||