<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Predicting Biological Degradation and Toxicity of Steroidal Estrogens"^^ . "This study was to construct a model to predict a variety of biological transformations of Ethinylestradiol\r\n(EE2) using electronic theory and to analyze the estrogenic potential of EE2 and its metabolites. As a\r\nsecondary goal, Frontier Electron Density (FED) theory was applied to the natural steroidal estrogens,\r\nestrone (E1), estradiol (E2) and estriol (E3) to determine if similar initiating reactions could be expected.\r\nElectron density profiles were calculated for EE2 metabolites to determine possible metabolic pathways\r\nup to the cleavage of the first ring. The pathways predicted in this study assume that enzymes commonly\r\nfound in wastewater treatment systems will be available to attack EE2 and each metabolite. Predictive\r\npathways were generated for EE2 based on the electron density and well established degradation rules. A\r\nnumber of metabolites were shown to be consistent with FED theory.\r\nThere are many methods available for effectively calculating the electron density of a given molecule.\r\nCalculations were carried out on the Pittsburgh Supercomputer (PSC) using the computational chemistry\r\nsoftware Gaussian 03. Two molecular orbital theories available for use in Gaussian 03 were used and\r\nresults compared to determine if the level of theory significantly affected the accuracy of the electron\r\ndensity calculations. In the beginning of this study only one theory was used but after studying the\r\navailable theories in more detail I implemented a theory that was shown to be more accurate in literature.\r\nUsing this information and well established degradation rules, metabolic pathways leading up to the first\r\nring cleavage were predicted. Experimentally measured metabolites appear in the predicted pathways.\r\nIn order to evaluate the environmental impacts of steroidal estrogens and their subsequent metabolites the\r\nestrogenic potential is calculated using chemaxon software. The estrogenic potential was estimated for\r\nEE2 and each of its metabolites both predicted and experimental as well as E1, E2 and E3 and known\r\nexperimentally measured metabolites that are similar to EE2. In all cases the estrogenic potential of the\r\nmetabolites indicate that they have a lower toxicity than the parent compounds but may still retain\r\nestrogenic potential after biotransformation."^^ . "2012-01-30" . . . . . . . . "William"^^ . "Barr"^^ . "William Barr"^^ . . . . . . "Predicting Biological Degradation and Toxicity of Steroidal Estrogens (PDF)"^^ . . . . . . "BarrWJFall2011.pdf"^^ . . . "Predicting Biological Degradation and Toxicity of Steroidal Estrogens (Indexer Terms)"^^ . . . . . . "indexcodes.txt"^^ . . . "Predicting Biological Degradation and Toxicity of Steroidal Estrogens (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "Predicting Biological Degradation and Toxicity of Steroidal Estrogens (Other)"^^ . . . . . . "preview.jpg"^^ . . . "Predicting Biological Degradation and Toxicity of Steroidal Estrogens (Other)"^^ . . . . . . "medium.jpg"^^ . . . "Predicting Biological Degradation and Toxicity of Steroidal Estrogens (Other)"^^ . . . . . . "small.jpg"^^ . . "HTML Summary of #10546 \n\nPredicting Biological Degradation and Toxicity of Steroidal Estrogens\n\n" . "text/html" . .