<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Baltrusaitis, Jonas</style></author><author><style face="normal" font="default" size="100%">Patterson, Eric V.</style></author><author><style face="normal" font="default" size="100%">O'Connor, Meghan</style></author><author><style face="normal" font="default" size="100%">Qu, Shen</style></author><author><style face="normal" font="default" size="100%">Kolodziej, Edward P.</style></author><author><style face="normal" font="default" size="100%">Cwiertny, David M.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Reversible Photohydration of Trenbolone Acetate Metabolites: Mechanistic Understanding of Product-to-Parent Reversion through Complementary Experimental and Theoretical Approaches.</style></title><secondary-title><style face="normal" font="default" size="100%">Environmental Science &amp; Technology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">trenbolone acetate metabolite reversible photohydration mechanism</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2016</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2016</style></date></pub-dates></dates><publisher><style face="normal" font="default" size="100%">American Chemical Society</style></publisher><volume><style face="normal" font="default" size="100%">50</style></volume><pages><style face="normal" font="default" size="100%">6753 - 6761</style></pages><isbn><style face="normal" font="default" size="100%">0013-936X</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Photolysis expts. (in H2O and D2O) and quantum chem. calcns. were performed to explore the pH-dependent, reversible photohydration of trenbolone acetate (TBA) metabolites.  Photohydration of 17α-trenbolone (17α-TBOH) and 17β-trenbolone (17β-TBOH) occurred readily in simulated sunlight to yield hydrated products with incorporated H+ at C4 and OH- at either C5 (5-OH-TBOH) or C12 (12-OH-TBOH) in the tetracyclic steroid backbone.  Although unable to be elucidated anal., theory suggests preferred orientations of cis-12-OH-TBOH (relative to C13 methyl) and trans-5-OH-TBOH, with the former most thermodynamically stable overall.  Both expt. and theory indicate limited stability of trans-5-OH-TBOH at acidic pH where it undergoes concurrent, carbocation-mediated thermal rearrangement to cis-12-OH-TBOH and dehydration to regenerate its parent structure.  Expts. revealed cis-12-OH-TBOH to be more stable at acidic pH, which is the only condition where its reversion to parent TBA metabolite occurred.  At basic pH cis-12-OH-TBOH decayed quickly via hydroxide/water addn., behavior that theory attributes to the formation of a stable enolate resistant to dehydration but prone to thermal hydration.  In a noteworthy deviation from predicted theor. stability, 17α-TBOH photohydration yields major trans-5-OH-TBOH and minor cis-12-OH-TBOH, a distribution also opposite that obsd. for 17β-TBOH.  Because H+ and OH- loss from adjacent carbon centers allows trans-5-OH-TBOH to dehydrate at all pH values, the presumed kinetically controlled yield of 17α-TBOH photohydrates results in a greater propensity for 17α-TBOH reversion than 17β-TBOH.  Addnl. calcns. explored minor, but potentially bioactive, trenbolone analogs that could be generated via alternative rearrangement of the acidic carbocation intermediate. [on SciFinder(R)]</style></abstract><issue><style face="normal" font="default" size="100%">13</style></issue><notes><style face="normal" font="default" size="100%">CAPLUS AN 2016:126331(Journal; Online Computer File)</style></notes></record></records></xml>