decabromodiphenyl-ethane and 1-2-dibromo-4-(1-2-dibromoethyl)cyclohexane

The production and use of nonpolybrominated diphenyl ether (non-PBDE), brominated flame retardant (BFR) alternatives have been on the rise, although their assessment in environmental samples is largely understudied. In the present study, several non-PBDE BFRs were found in the egg pools of herring gulls (Larus argentatus) from seven colonies in the five Laurentian Great Lakes (collected in 1982 to 2006). Of the 19 BFRs monitored, hexabromobenzene (HBB), 1,2-bis(2,4,6-tribromophe-noxy)ethane (BTBPE), decabromodiphenyl ethane (DBDPE), and alpha-, beta-, gamma-, and delta-isomers of 1,2-dibromo-4-(1,2-dibromoeth-yl)cyclohexane (TBECH) were present in eggs from all the colonies with the highest detection frequencies of 100%, 54%, 9% and 97%, respectively. In 2005 and 2006 eggs, the concentrations of DBDPE were highest at three of the seven colonies (1.3 to 288 ng/g wet weight (ww)) and surpassed decabromodiphenyl ether (BDE-209). HBB (0.10 to 3.92 ng/g ww), BTBPE (1.82 to 0.06 ng/g ww), and Sigma-TBECH (0.04 to 3.44 ng/g ww; mainly the beta-isomer 52 to 100% of Sigma-TBECH) were detected at lower concentrations (and generally <

Topics: Animals; Bromobenzenes; Charadriiformes; Cyclohexanes; Environmental Monitoring; Flame Retardants; Geography; Great Lakes Region; Halogenated Diphenyl Ethers; Isomerism; Ovum; Population Dynamics; Time Factors

To investigate androgen receptor (AR) activation by exogenous compounds, we used a combination of experimental analysis and theoretical modeling to compare a set of brominated flame retardants (BFRs) to dihydrotestosterone (DHT) with regard to ligand docking, AR binding, and AR activation in human hepatocellular liver carcinoma cells, as well as interacting energy analysis. Modeling of receptor docking was found to be a useful first step in predicting the potential to translocate to the ligand pocket of the receptor, and the computed interaction energy was found to correlate with the observed binding affinity. Flexible alignment studies of the BFR compounds demonstrated that 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (BCH) closely overlap DHT. Combining the theoretical modeling with in vitro ligand-binding and receptor-activation assays, we show that BCH binds to and activates the human AR. The remaining BFRs did not successfully interact with the ligand pocket, were not able to replace a synthetic androgen from the receptor, and failed to activate the receptor.

Topics: Androgens; Binding, Competitive; Cell Line, Tumor; Cyclohexanes; Endocrine Disruptors; Flame Retardants; Humans; Ligands; Models, Molecular; Receptors, Androgen