Using electronic theory to identify metabolites present in 17α-ethinylestradiol biotransformation pathways

William J. Barr, Taewoo Yi, Diana Aga, Orlando Acevedo, Willie F. Harper

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


This research used electronic theory to model the biotransformation of 17α-ethinylestradiol (EE 2) under aerobic conditions in mixed culture. The methodology involved determining the Frontier Electron Density (FED) for EE 2 and various metabolites, as well as invoking well-established degradation rules to predict transformation pathways. We show that measured EE 2 metabolites are in good agreement with what is expected based on FED-based modeling. Initiating reactions occur at Ring A, producing metabolites that have been experimentally detected. When OH-EE 2 and 6AH-EE 2 are transformed, Ring A is cleaved before Ring B. The metabolites involved in these pathways have different estrogenic potentials, as implied by our analysis of the log P values and the hydrogen bonding characteristics. The OH-EE 2 and 6AH-EE 2 transformation pathways also show redox-induced electron rearrangement (RIER), where oxidation reactions lead to the reduction of carbon units present along the bond axis. Sulfo-EE 2 appears to be difficult to biotransform. These findings clarify theoretical and practical aspects of EE 2 biotransformation.

Original languageEnglish (US)
Pages (from-to)760-768
Number of pages9
JournalEnvironmental Science and Technology
Issue number2
StatePublished - Jan 17 2012
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry


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